Dr Nihal Martis
email: martis.n@chu-nice.fr

Matthieu Jamme

Corinne Bagnis-Isnard

Claire Pouteil-Noble

Claire Presne

Cécile Vigneau

Steven Grangé

Stéphane Burtey

Jean-Philippe Coindre

Alain Wynckel

Mohamed A Hamidou

Tarik Kanouni

Elie Azoulay

Miguel Hie

Dominique Chauveau

Agnès Veyradier

Eric Rondeau

Paul Coppo
email: paul.coppo@aphp.fr

Systemic autoimmune disorders associated with haemolytic uremic syndrome: a crosssectional analysis from the French National TMA registry

Keywords: Systemic autoimmune disease-associated HUS Thrombotic microangiopathy, haemolytic uremic syndrome, autoimmune disease, connective tissue disease, systemic lupus, systemic sclerosis

Context. Systemic auto-immune diseases (SAID)-associated atypical haemolytic uremic syndrome (HUS) is a rare disorder within the spectrum of thrombotic microangiopathies (TMA) whose management remains debated.

Objectives. To provide a demographic, clinical and therapeutic picture of SAID-HUS. Methods. A cross-sectional analysis was conducted on adult patients presenting with SAID and HUS from the French National TMA Registry over a 20-year period. Clinical features were extracted and compared to those from a historical cohort of aHUS patients.

Results. Forty-one patients with SAID-HUS were compared to 78 patients with aHUS from a historical cohort. Thirtynine connective tissue diseases (CTD) were found: systemic lupus erythematosus (n=18), primary Sjögren's syndrome (n=6), systemic sclerosis (n=11), mixed CTD (n=2) and 2 cases of vasculitides, including 7 overlapping forms and 8 cases of primary antiphospholipid syndromes (APLS). Patients with SAID-HUS generally had pre-existing chronic kidney failure (OR= 3.17, 95%CI: 1.204 to 7.923; p= 0.016) compared to aHUS patients, though creatinine levels were significantly lower (216 [IQR, µmol/L vs. 368 [IQR, µmol/L; p= 0.002). Patients were less likely to recover if renal replacement therapy was needed at onset (OR= 0.07; 0.02 to 0.34; p <0.0005). Two patients died. Thirty patients responded to immunosuppressive treatment and complete remission was achieved in 25 cases. By contrast, TPE did not have an early effect on TMA features at Day-7 nor Day-15 (p >0.05).

Conclusion. The management of SAID-HUS implies an early initiation of immunosuppressive drugs for flares of the associated SAID, whereas TPE seem ineffective.

Introduction

The term thrombotic microangiopathy (TMA) defines a syndrome characterized by the association of a peripheral thrombocytopenia, a mechanical haemolytic anaemia and organ failure [START_REF] George | Syndromes of thrombotic microangiopathy[END_REF]. Thrombotic thrombocytopenic purpura (TTP) and the haemolytic uremic syndrome (HUS) (including Shigatoxin-associated HUS and atypical HUS [aHUS]) are the two most common forms of TMA. aHUS can also occur in association with treatments such as antineoplastic agents, recreational drugs, or various other conditions such as transplantation, malignant hypertension or systemic auto-immune diseases (SAID). From a pathophysiological viewpoint, features of TMA reflect vascular damage with arteriolar and capillary thrombosis and endothelial abnormalities occurring in patients with determined risk factors [START_REF] George | Syndromes of thrombotic microangiopathy[END_REF]. TTP results from a severe deficiency in the von Willebrand factor-cleaving protease ADAMTS13 (A Disintegrin and Metalloproteinase with ThromboSpondin-1 motifs; 13th member), that is either due to antibodies directed against the enzyme (immune-mediated TTP [iTTP]) or to biallelic mutations of the encoding gene. aHUS is, on the other hand, a consequence of a deregulation of the alternative complement pathway that leads to excessive endothelial deposits of C5a and C5b9 [START_REF] Loirat | Atypical hemolytic uremic syndrome[END_REF]. Of note, when TMA is associated with an underlying condition -typically with detectable or normal ADAMTS13 activity, it is usually referred to as "secondary aHUS" [3]. However, whether alterations in the alternative complement pathway play a part in secondary aHUS is still a matter of debate [3].

TMA seem to be overrepresented in patients with SAID [4,[START_REF] Mariotte | Epidemiology and pathophysiology of adulthood-onset thrombotic microangiopathy with severe ADAMTS13 deficiency (thrombotic thrombocytopenic purpura): a cross-sectional analysis of the French national registry for thrombotic microangiopathy[END_REF]. A previous study had sought to characterize autoimmune diseases associated with iTTP [START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF]. Such forms make up less than 15% of all iTTP [START_REF] Mariotte | Epidemiology and pathophysiology of adulthood-onset thrombotic microangiopathy with severe ADAMTS13 deficiency (thrombotic thrombocytopenic purpura): a cross-sectional analysis of the French national registry for thrombotic microangiopathy[END_REF]. Though therapeutic management as well as prognostic factors such as relapse, flare-up or death did not significantly differ from those of iTTP without SAID [START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF] -on iTTP diagnosis, anti-dsDNA and anti-SSA antibody-positivity were found to be potential risk factors for the development of SAID [START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF]. In patients with a detectable ADAMTS13 activity, microangiopathic haemolytic anaemia and thrombocytopenia may be primary features of SAID, suggesting that "secondary aHUS" is more common in SAID than previously thought [START_REF] Scully | Consensus on the standardization of terminology in thrombotic thrombocytopenic purpura and related thrombotic microangiopathies[END_REF]. SAID-associated HUS have been difficult to assess due to knowledge gaps that range from epidemiological features, to clinical presentations and treatment strategies. SAID-HUS may also differ from aHUS whose prognosis has greatly improved during the last decade as comprehension of pathophysiological mechanisms have increased and have led to treatment strategies involving anti-complement agents [START_REF] Afshar-Kharghan | Atypical hemolytic uremic syndrome[END_REF].

SAID-HUS have heterogeneous presentations -with systemic lupus erythematosus (SLE) being its best described aetiology [START_REF] Song | The spectrum of renal thrombotic microangiopathy in lupus nephritis[END_REF][START_REF] Barrera-Vargas | Renal Thrombotic Microangiopathy in Proliferative Lupus Nephritis: Risk Factors and Clinical Outcomes: A Case-Control Study[END_REF][START_REF] Yue | Characteristics and Outcomes of Patients with Systemic Lupus Erythematosus-associated Thrombotic Microangiopathy, and Their Acquired ADAMTS13 Inhibitor Profiles[END_REF]. Other forms include (but are not limited to APLS [START_REF] Kello | Secondary thrombotic microangiopathy in systemic lupus erythematosus and antiphospholipid syndrome, the role of complement and use of eculizumab: Case series and review of literature[END_REF] and scleroderma renal crises (SRC) [START_REF] Guillevin | Scleroderma renal crisis: a retrospective multicentre study on 91 patients and 427 controls[END_REF]. In some cases, TMA is purely renal and diagnosis is ultimately histopathological [START_REF] Kotzen | Antiphospholipid Syndrome Nephropathy and Other Thrombotic Microangiopathies Among Patients With Systemic Lupus Erythematosus[END_REF]. This begs the role of immunosuppressive treatment to control the underlying SAID in the management of patients with SAID-HUS, and whether TPE and complement blocking strategies should be given in such circumstances, as it is the case for aHUS [START_REF] Legendre | Terminal complement inhibitor eculizumab in atypical hemolytic-uremic syndrome[END_REF][START_REF] Jamme | Predictive features of chronic kidney disease in atypical haemolytic uremic syndrome[END_REF].

We chose to focus, through a cross-sectional analysis of data from the French national TMA registry, on this lesser-known group of SAID presenting with TMA in adult subjects. Our objectives are to provide a demographic and clinical picture of SAID-HUS and assess therapeutic approaches.

Materials and Methods

Study population and definitions

Over a period spanning from October 2000 to October 2019, records of adult patients (age > 18 years) included in the registry of the French reference centre for TMAs were extracted (Supplementary material). TMA patients who fulfilled criteria for SAID -but with a detectable ADAMTS13 activity (≥ 20%) to exclude patients with TTP -were included in the study (Figure 1). To address whether SAID modifies clinical presentation or impacts prognosis, characteristics of these patients were then compared to those of a historical cohort of adult (≥ 18 years) aHUS patients, from our Registry, without SAID, but with detectable ADAMTS13 activity [START_REF] Jamme | Predictive features of chronic kidney disease in atypical haemolytic uremic syndrome[END_REF]. These aHUS patients did not have confounding factors such as HIV infection, cancer and/or chemotherapy, transplantation, and malignant hypertension. Patients with Shiga-toxin and Escherichia sp. associated-infections were also excluded.

Flare-ups and relapses were defined as per the Consensus terminology promoted by the International Working Group for TTP [START_REF] Scully | Consensus on the standardization of terminology in thrombotic thrombocytopenic purpura and related thrombotic microangiopathies[END_REF]. Durable platelet recovery was defined as a sustained normalisation of the platelet count at Day-15 from the initiation of therapeutic plasma exchange (TPE). Kidney failure was defined by an estimated glomerular filtration rate (eGFR) of less than 60 mL/mn/1.73m² or, when eGFR was unavailable, plasma creatinine levels of more than 100 µmol/L. SLE was mostly defined according to the 2019 European League Against Rheumatism (EULAR) / American College of Rheumatology (ACR) classification criteria, but previous international classification criteria were also accepted [START_REF] Aringer | European League Against Rheumatism/American College of Rheumatology Classification Criteria for Systemic Lupus Erythematosus[END_REF][START_REF] Petri | A Comparison of 2019 EULAR/ACR SLE Classification Criteria with Two Sets of Earlier SLE Classification Criteria[END_REF]. APLS could also refer to patients presenting with its catastrophic form [START_REF] Miyakis | International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS)[END_REF][START_REF] Cervera | Validation of the preliminary criteria for the classification of catastrophic antiphospholipid syndrome[END_REF], prior to the knowledge of TMA on renal biopsies. Primary Sjögren's syndrome (pSS) was diagnosed based on the 2016 ACR/EULAR consensus [START_REF] Shiboski | American College of Rheumatology/European League Against Rheumatism Classification Criteria for Primary Sjögren's Syndrome: A Consensus and Data-Driven Methodology Involving Three International Patient Cohorts[END_REF] whereas diagnoses of systemic sclerosis (SSc) were reassessed using the 2013 ACR/EULAR criteria [START_REF] Van Den Hoogen | classification criteria for systemic sclerosis: an American college of rheumatology/European league against rheumatism collaborative initiative[END_REF]. Patients with SAID were required to not have cancer or HIV infection. All cases were reviewed for accuracy by 2 senior authors (NM and PC).

Clinical parameters

Clinical features on admission were systematically extracted. For patients with available data, outcome was assessed at three, six and twelve months. Previously identified prognostic features, such as lactate dehydrogenase (LDH) levels and central nervous system involvement, were similarly described [START_REF] Benhamou | Development and validation of a predictive model for death in acquired severe ADAMTS13 deficiency-associated idiopathic thrombotic thrombocytopenic purpura: the French TMA Reference Center experience[END_REF]. The French score [START_REF] Coppo | Predictive features of severe acquired ADAMTS13 deficiency in idiopathic thrombotic microangiopathies: the French TMA reference center experience[END_REF] was systematically determined for each subject : a platelet count < 30.10E9/L and serum creatinine < 200 µmol/L being highly suggestive of TTP. We also sought to calculate the chronic kidney disease (CKD) score described in [START_REF] Jamme | Predictive features of chronic kidney disease in atypical haemolytic uremic syndrome[END_REF], in the event that it could be used as a marker for SAID-TMA. ADAMTS13 activity and anti-ADAMTS13 antibodies were assessed as previously described [START_REF] Mariotte | Epidemiology and pathophysiology of adulthood-onset thrombotic microangiopathy with severe ADAMTS13 deficiency (thrombotic thrombocytopenic purpura): a cross-sectional analysis of the French national registry for thrombotic microangiopathy[END_REF].

Renal biopsies

Histopathology reports of patients with SAID-TMA who underwent routine renal biopsies were reclassified according to the following categories: glomerular injury, tubular injury, endocapillary hypercellularity, interstitial fibrosis and vascular lesions. Lupus nephritis class was determined based on the 2003 International Society of Nephrology and Renal Pathology Society (ISN/RPS) classification [START_REF] Weening | The Classification of Glomerulonephritis in Systemic Lupus Erythematosus Revisited[END_REF]. Histological evidence of SRC and APLS was also noted based on pathological records.

Treatment

Treatment strategies including hospitalization in intensive care units, transfusion of blood and blood products, TPE, corticosteroids, hydroxychloroquine, immunosuppressors, disease-modifying anti-rheumatic drugs (DMARDs), and biologics (i.e. rituximab and eculizumab) were reported.

Statistical analysis

Continuous variables are expressed as median values with their interquartile range (IQR) and extreme values are specified when appropriate. Differences between groups were analysed using the Mann-Whitney test.

The chi-square test was used to study statistical associations between qualitative variables. Odds ratios (OR) and their 95% confidence intervals (95%CI) were calculated accordingly and Fisher's exact test used for P-value calculations. Due to the small study samples, logistic regression was not conducted. P-values of less than 0.05 were considered statistically significant using two-sided tests. Statistical analyses were performed with GraphPad® Prism 6.2 and MS Excel 2010.

Ethics

Informed patient consent was gathered as part of routine clinical practice and data were anonymized at the time they were recorded for the Registry. Due to its retrospective approach, this study did not require specific approval from an institutional review board. Data storage and its use complied with standards of the French Data Protection Authority (Supplementary material).

Results

Patient characteristics

Sixty-two cases from a total of 2493 patient-files were extracted from the Registry using filters for "autoimmune disease" and "HUS" (Figure 1). Fourteen records were wrongly classified owing to organ specific autoimmune disease (such as autoimmune thyroiditis, or multiple sclerosis) (n=3), or incomplete classification criteria for the suspected connective tissue disease (CTD) and/or missing data (n=11). Ultimately, 41 cases of SAID-HUS were available for analysis. From the historical cohort of aHUS -after excluding malignant hypertensionrelated causes -78 patients were included for the group comparison (Figure 1). Of these 78 patients, a full complement deficiency workup was performed in 56 cases and mutations were identified in 12 cases (21.4%): CFH (n=5), CFI (n=4), MCP (n=2) and C3 (n=1).

Details on SAID are presented in Table 1. Overlapping forms of CTD are represented in a Venn diagram (Figure 2a). Ten patients had a positive workup for antiphospholipids of which, 4 were "triple positive" for lupus anticoagulant, anti-β2-glycoprotein I and anti-cardiolipin antibodies. Antiphospholipid antibodies were identified on multiple occasions not less than 12 weeks apart in 8 documented cases. However, none showed signs of macrovascular thrombosis at the time of aHUS and ALPS was diagnosed concomitantly to TMA features in all but 2 cases. Two patients had systemic vasculitides consisting in polyarteritis nodosa with renal involvement and ANCApositive renal micropolyangeitis (reported in [START_REF] Dellal | Thrombotic microangiopathy associated with anti-neutrophil cytoplasmic antibody-associated vasculitis: a French nationwide retrospective casecontrol study and literature review[END_REF]). In 10/41 cases, the diagnosis of SAID was made at the same time as that of aHUS or briefly after. In the 31 remaining cases, the pre-existing SAID was known to the clinician. The median time between the first manifestations of SAID and TMA was of 3.34 years (IQR, 13.5 days-3.45 years). No SAID was reported during the follow-up of patients from the historical aHUS cohort.

Clinical features of SAID-HUS (Table 2)

Patients with SAID-HUS were in their early forties at the time of diagnosis. They were mostly females and unlike aHUS subjects, were more often known to have pre-existing chronic kidney failure (OR= 3.17, 95%CI: 1.204 to 7.923; p= 0.023) than aHUS patients, though creatinine levels at presentation were significantly lower (p=0.002) (Table 2). LDH levels were also lower. There was no difference in the CKD score [START_REF] Jamme | Predictive features of chronic kidney disease in atypical haemolytic uremic syndrome[END_REF] between either group.

Neurological involvement and cardiovascular features (i.e. hypertension) had a comparable prevalence between SAID-HUS and aHUS. Kidney and neurological involvement whether associated or not with TMA defined active SAID. Overall, 23/41 patients were previously following immunosuppressive therapy for their SAID at the time of aHUS diagnosis.

Long-term therapy with DMARDs prior to admission was mostly given to SLE patients: methotrexate (n=4), mycophenolate mofetil (n=4) and azathioprine (n=2). Only 2/11 patients with SSc had ongoing steroid therapy prior to their hospitalization, but dosing was not recorded. At the time of the diagnosis of SRC, patients with SSc had a disease progression of less than 4 years and positive anti-centromere (n=1), anti-topoisomerase I (n=3), anti-RNApolymerase III (n=1) and anti-PM-Scl (n=2) antibodies. These markers overlapped with anti-SSA antibodies on 2 occasions.

Renal biopsies were performed in 26 SAID-HUS patients. Pathological lesions were mostly glomerular (n=24) with an overlap of tubular lesions (Figure 2b). TMA-specific features were described in 25/26 kidney specimens (Figure 2c) with 16 lupus-related glomerulonephritis and 4 SRC. Lupus nephritis presented the following classes: II (n=2), III (n=2), IV (n=7), IV+V (n=1) and V (n=2). Reports also documented endocapillary hypercellularity (11/14) and interstitial fibrosis (11/12). Vascular damage was found in 22/26 specimens. Lympho-plasmocytic infiltration was identified in pSS irrespectively of signs of cryoglobulinaemic vasculitis. Activity and chronicity indexes were not systematically available for SLE specimens and were therefore not studied.

Three female patients with SAID-HUS (i.e. 2 APLS and 1 SLE) were pregnant at the time of HUS diagnosis and pregnancy outcomes were favourable with deliveries occurring within the 27 th and the 34 th weeks of gestation.

Treatment and outcomes

More than half of patients with SAID-HUS were hospitalized in an intensive care unit (ICU) and 18/41 required renal replacement therapy. Six patients, who had a French score of 2, received TPE with a median of 4.5 (IQR, 1.75-6.5) procedures. For these patients, TPE -but also caplacizumab (n=1) -were discontinued when iTTP was eliminated in patients with SLE, MCTD, SSc and ALPS (Table 2). However, 22 patients were treated with TPE despite having features of aHUS (French score ≤1) and/or ADAMTS13 activity ≥20%. These patients received between 3 to 53 TPE procedures (median number of procedures of 14 [IQR, 9.75-25]) that were usually followed by immunosuppressive therapy. Both patients with vasculitides received TPE. Treatment combinations associating TPE (n=26) and their outcomes are presented in table 3. Of interest, all 26 SAID-HUS patients had received steroids or immunomodulatory/immunosuppressive drugs prior to TMA. Figure 3 illustrates the trend in platelet counts in 10 patients with SLE with sufficiently available biological data who underwent TPE procedures and suggests that TPE was unable to provide an early improvement of TMA. Conversely, an effect on platelet count, kidney function as well as sustained haematological response resulted from concomitant immunosuppressors. This is highlighted by the remaining 15 patients who did not receive TPE and were treated specifically for their SAID with similar outcomes. Overall, when early platelet-response (i.e. platelet count ≥150.10E9/L) was compared between patients receiving TPE (n=16) and those who did not (n=11): there was no statistically significant differences at Day-7 (p=0.440) and/or Day-15 (p=0.180). The 3 patients who had been started on second-line eculizumab therapy after receiving steroids and TPE for SSc, SLE and MCTD were respectively taken off the drug after 6, 3 and 2 infusions. The patient with MCTD died shortly after the 2 nd infusion. Complete remission was only obtained in the case of SSc but could not be attributed to eculizumab as the diagnosis of SRC led to a change in the therapeutic approach (i.e. discontinuation of steroids).

The SLE patient did not receive an immunosuppressor despite having focal and segmental glomerulosclerosis on kidney biopsy and was lost to follow-up after 104 days. None of the 3 patients had antiphospholipid antibody markers.

TMA was treated as a flare-up of SAID in 30 cases, with an induction therapy of either rituximab (n=5) or cyclophosphamide (n=6), or both (n=3) in the case of SLE, APLS and medium/small vessel vasculitides. DMARDS were usually either mycophenolate mofetil (n=7), azathioprine (n=1), tacrolimus (n=1), or methotrexate (n=1) and used as maintenance therapy. Complete remission was achieved after splenectomy in a setting of refractory TMA due to SLE-associated catastrophic APLS. None of the patients received platelet transfusions. All 30 patients responded to treatment with complete remission being documented in 25 cases. Remission was achieved after a median of 30 days (IQR, 18;62.5). Durable recovery from kidney failure was achieved in 4/22 patients and 3/22 patients required chronic dialysis, which was not significantly different from the 17/78 aHUS patients (p=0.069).

Four patients experienced treatment refractoriness (i.e. patients without a durable platelet recovery in relation to an ongoing HUS): SSc (n=2), SLE (n=1), APLS (n=1). The 2 patients with SSc were on steroids, and patients with the SLE and ALP S received immunosuppressive therapy. SAID-HUS flare-ups were described in 2 cases and there were only 2 cases of relapse. Neither flare-up episodes nor relapses were associated with death.

Out of 17 patients with central nervous system features, 14 had a complete recovery of neurological symptoms while the remaining 3 had stroke sequelae.

Hospital stays lasted a median of 28 days (IQR, 18.5-55) (range, 6-353 days). Two patients, one with SSc and the other with MCTD, died during their hospitalization at day-15 and day-26, respectively.

Prognostic markers for SAID-HUS

Patients were less likely to achieve complete remission of SAID-HUS if they needed renal replacement therapy at the onset (OR= 0.07; 0.02 to 0.34; p <0,001). Steroid treatment and anti-hypertensive drugs taken prior to the TMA could not be associated with more complete remission. Neither renal replacement therapy nor intensive care were associated with worse long-term outcomes. None of the clinical nor biological features were significantly associated with remission status. On the other hand, patients achieving remission had lower plasma urea levels (p= 0.002). There was no difference in platelet values or serum creatinine levels between responders and nonresponders. Lastly, SRC without the appropriate support treatment including angiotensin-converting enzyme (ACE) inhibitors and the early discontinuation of steroids were less likely to respond than SLE patients.

Long-term follow-up

Relapse of SAID-HUS was noted in one SLE patient who experienced a flare-up. The only other case of HUS relapse was identified in another SLE patient who was previously believed to have Evans syndrome (i.e. positive direct antiglobulin test) and who presented with hypertensive encephalitis. Signs of TMA and lupus nephritis were found on the renal biopsy of this patient but no further signs for a lupus flare were found.

Since discharge from hospital, follow-up ranged from 2 days to 6.34 years.

Discussion

This cross-sectional analysis provides a new insight into SAID-HUS. Small sample sizes in mostly retrospective cohorts and undifferentiation between TTP and other forms of TMA in previously published series have led to few changes to the clinical approach of SAID-HUS. To the best of our knowledge, ours is the first to assess SAID-HUS and evaluate its management.

Unlike SAID associated with iTTP, those occurring in aHUS either precede microangiopathic signs or are found simultaneously [START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF][START_REF] Chen | Thrombotic microangiopathy in systemic lupus erythematosus: a cohort study in North Taiwan[END_REF]. Hence, up to a quarter of patients had a known active SAID at the time SAID-HUS was suspected. SLE and pSS are just as frequently observed in SAID-HUS as in iTTP, reflecting the prevalence of these CTD amongst SAID [START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF]. Moreover, there is no evidence to support that one group presented with more severe forms of SAID.

Few biological markers setting apart SAID-HUS from aHUS are available to clinicians. Kidney failure is often less pronounced even though patients with SAID-HUS present more frequently with chronic kidney disease. Extrarenal and extra-haematological features, especially CNS involvement, can however be suggestive of HUS diagnosis in the context of SAID and highlight the importance of a clinical knowledge of CTD. However, inflammatory rheumatic disorders without overt physical signs -such as pSS -or primary APLS, may be more problematic to identify and to treat. It thus becomes crucial to have immunological markers (i.e. antinuclear antibodies) to provide early diagnoses of CTD since SAID-HUS are to be treated differently from aHUS. Unsurprisingly, SLE is the most prevalent aetiology of SAID-HUS. It is also the most frequently diagnosed CTD [START_REF] Durcan | Management strategies and future directions for systemic lupus erythematosus in adults[END_REF]. TMA represents around 10% of cases of lupus nephritis [START_REF] Barrera-Vargas | Renal Thrombotic Microangiopathy in Proliferative Lupus Nephritis: Risk Factors and Clinical Outcomes: A Case-Control Study[END_REF][START_REF] Barber | Evaluation of clinical outcomes and renal vascular pathology among patients with lupus[END_REF]. It is known as one of the most severe forms of renal vascular disease in SLE with a high mortality rate, and appears to be an independent risk factor for renal outcome in lupus nephritis [START_REF] Song | The spectrum of renal thrombotic microangiopathy in lupus nephritis[END_REF]. Generally, these patients present only with pathologically evidence of TMA but they have also been found to have fairly active diseases with increased SLEDAI scores as it was the case in our series [START_REF] Song | The spectrum of renal thrombotic microangiopathy in lupus nephritis[END_REF][START_REF] Chen | Thrombotic microangiopathy in systemic lupus erythematosus: a cohort study in North Taiwan[END_REF]. TMA is systematically found with lupus nephritis [4]. Diagnosing lupus in such circumstances is rarely challenging since most patients have systemic manifestations (i.e. cutaneous, articular, pleural, respiratory and even neurological features) [4,[START_REF] Song | The spectrum of renal thrombotic microangiopathy in lupus nephritis[END_REF]. Echoing findings from previous studies on TMA-associated CTD, antiphospholipid antibodies were not predisposing conditions for TMA [4,[START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF]. On the other hand, very little is known of pSS associated-TMA and only 6 cases (including overlap syndromes) were documented over the 20-year period of the Registry. pSS associated-TMA is uncommon and has been described in the context of iTTP and to a lesser extent in aHUS [START_REF] Roriz | Risk Factors for Autoimmune Diseases Development After Thrombotic Thrombocytopenic Purpura[END_REF][START_REF] Xu | Sjögren's syndrome initially presented as thrombotic thrombocytopenic purpura in a male patient: a case report and literature review[END_REF][START_REF] Cheng | Thrombotic microangiopathy complicating newly diagnosed Sjögren's syndrome in a dialysis patient[END_REF]. Typical renal features of pSS are tubulo-interstitial and result from lymphoplasmocytic infiltration [START_REF] Bossini | Clinical and morphological features of kidney involvement in primary Sjögren's syndrome[END_REF].

Of importance, SRC is associated with mortality, and though it occurs in less than 5% of patients with SSc, identifying adverse prognostic factors -such as the use of high-dose steroids -is crucial for its proper management [START_REF] Mouthon | Scleroderma renal crisis[END_REF][START_REF] Woodworth | Scleroderma renal crisis and renal involvement in systemic sclerosis[END_REF].

There is no clear consensus on the therapeutic approach to SAID-HUS. In most cases, treatment of the SAID with immunosuppressive drugs led to the control and even to the remission of the TMA syndrome along with its associated SAID. Accounting for refractory disease, TPE was still liberally used despite the lack of evidence for its efficacy in SLE and other connective tissue disorders [START_REF] Schwartz | Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue[END_REF][START_REF] Loo | Immunoadsorption and plasmapheresis are equally efficacious as adjunctive therapies for severe lupus nephritis[END_REF]. Moreover, TPE has not been found to improve mortality or prevent end-stage kidney disease in ANCA-associated vasculitides [START_REF] Walsh | Plasma Exchange and Glucocorticoids in Severe ANCA-Associated Vasculitis[END_REF], and evidence is lacking to suggest its efficacy in vasculitides-associated TMA. As the management of SAID-HUS mostly requires controlling the underlying CTD, it is likely that TPE lacks efficacy in SAID-HUS. Our results cannot support the use of TPE for the treatment of SAID-HUS.

We found that despite the heterogeneity of the cohort, mortality is relatively low in SAID-HUS as only 2 deaths associated with refractory disease were reported. One of the 2 patients who died presented with a refractory SRC despite symptomatic measures and the other, suffering from MCTD, did not receive immunosuppressive therapy. Patients with SSc need to be considered as a high-risk group for mortality [START_REF] Mouthon | Scleroderma renal crisis[END_REF]. This implies that controlling the underlying SAID is the cornerstone of the treatment of SAID-HUS and that a delay in immunosuppressive therapy may negatively impact the overall prognosis.

Eculizumab was used in only 3 cases, including for SRC, with disappointing results. Previous case-series and reviews have also failed to provide solid evidence for the efficacy of eculizumab in SLE-associated TMA [START_REF] Kello | Secondary thrombotic microangiopathy in systemic lupus erythematosus and antiphospholipid syndrome, the role of complement and use of eculizumab: Case series and review of literature[END_REF][START_REF] Wright | A systematic review of the role of eculizumab in systemic lupus erythematosus-associated thrombotic microangiopathy[END_REF]. In most cases, patients received other immunosuppressive drugs either prior and/or in combination with eculizumab [START_REF] Wright | A systematic review of the role of eculizumab in systemic lupus erythematosus-associated thrombotic microangiopathy[END_REF]. There are no controlled trials involving the latter for the treatment of CTD-associated TMA. Other than in refractory (catastrophic) APLS, we believe that eculizumab cannot be promoted in SAID-HUS at this time [START_REF] Kello | Secondary thrombotic microangiopathy in systemic lupus erythematosus and antiphospholipid syndrome, the role of complement and use of eculizumab: Case series and review of literature[END_REF][START_REF] Cervera | The diagnosis and clinical management of the catastrophic antiphospholipid syndrome: A comprehensive review[END_REF].

Our study has limitations. There was no centralized testing of immunological markers and/or their retesting; and parameters for SAID activity (i.e. such as complement fractions) are not reported as these data were often lacking in patient files submitted to our Registry. Furthermore, we do need to acknowledge the selection bias due to improvements made to the management and understanding of SRC that have led to fewer cases and reduced mortality over time [START_REF] Bose | Scleroderma renal crisis[END_REF]. In the same vein, it is likely that SRC and lupus nephrites were managed in expert centres that did not systematically perform ADAMTS13 dosing for TMA, precluding the patient's inclusion in the Registry.

Despite these drawbacks, we were able to pretty reliably describe a mostly overlooked group of TMA. Our findings reflect what has previously been described in cancer-associated TMA [START_REF] Thomas | Microangiopathy in Cancer: Causes, Consequences, and Management[END_REF] -in the sense that treating the underlying disease is crucial to managing aHUS, and that TPE is probably ineffective.

In the setting of such infrequent clinical entities, we believe in the implementation of prospective long-term patient registries to gain better knowledge of heterogeneous diseases such as SAID-TMA. The absence of standards of care require a more systematic approach that includes performing timely renal biopsies. Furthermore, the management of SAID-HUS relies on clinical understanding of CTD, as some SAID (i.e. SSc) require a specific therapeutic approach. The latter revolves around treating SAID flares and/or its systemic complications by initiating immunosuppressive therapies. Table 1. Diagnoses-associated with SAID-HUS, immunological features, treatment strategies.

Tables

SAID-HUS (N=41) Clinical aspects

FiguresFigure 1 .

 1 Figures

  Figure 1. Study flow-chart.

Figure 2 .

 2 Figure 2. Venn diagrams of a) overlapping connective tissue diseases and APLS, b) the distribution of glomerular and tubular lesions in renal biopsies, and c) histopathological diagnoses. Abbreviations: SLE= systemic lupus erythematosus, APLS= antiphospholipid syndrome, pSS= primary Sjögren's syndrome, SSc= systemic sclerosis and TMA= thrombotic microangiopathy.

Table 2 .

 2 Demographics, clinical, biological and radiological features at baseline.

	Connective tissue disease and APLS, n	39
	Systemic lupus erythematosus, n	19
	Primary Sjögren's syndrome, n	7
	Systemic sclerosis, n	11
	Mixed connective tissue disease, n	2
	Primary APLS, n	8
	Overlap forms, n	7
	Vasculitides, n	2
	Ongoing treatments at baseline
	Anticoagulant treatment, n	5
	Antiplatelet drug, n	1
	Hydroxychloroquine, n	14
	Steroids, n	10
	DMARD, n	10
	Cyclophosphamide, n	7
	Rituximab, n	1
	Intravenous immunoglobulins, n	1
	Treatment strategies for TMA
	Hospitalization in Intensive care	27
	Antithrombotic treatment, n	17
	Antihypertension drugs, n	35
	Renal replacement therapy, n	18
	Plasma exchange therapy, n	26
	Number of TPE procedures, median [IQR]	10 [2-17.5]
	Steroids, n	30
	Hydroxychloroquine, n	15
	DMARD, n	9
	Cyclophosphamide, n	9
	Rituximab, n	11
	Caplacizumab, n	1
	Packed red blood cell transfusions, n	23
	Number of transfused packed red blood cells, median, [IQR]	2 [1-8]
	Fresh frozen plasma transfusions, n	13
	Eculizumab, n	3

(n=46)

Funding statement

This study did not receive any financial support.

Data availability statement

The data underlying this article will be shared on reasonable request to the corresponding author.

Disclosure statement

The authors do not declare any conflicts of interest with the current study.

Supplementary Material

Study population and definitions

The French National TMA Registry (referred to hereinafter as the Registry) is an initiative of the French Reference Centre for TMA that is supported by the Ministry for Health. Twenty-seven participating centres provide a network of immunology, haematology, nephrology and intensive care departments that regularly update this valuable database of patients presenting with TMA across the country (www.cnr-mat.fr). Patients that are included in the Registry present either with biological criteria for TMA (i.e. microangiopathic anaemia and/or thrombocytopenia, with or without organ failure), or with pathological evidence of TMA.

Ethics

'Commission Nationale Informatique et Libertés', CNIL, autorisation n°911539, and 'Comité consultatif sur le traitement de l'information en matière de recherche dans le domaine de la santé', CCTIRS, autorisation n°11.537, Paris, France.


domain: sdv sde

text:
Daria Vilkova

Christine Chene

Elena Kondratenko

Romdhane Karoui
email: romdhane.karoui@univ-artois.fr

A comprehensive review on the assessment of the quality and authenticity of the sturgeon species by different analytical techniques

Keywords: Sturgeon, Authenticity, Quality, Freshness, Targeted and untargeted techniques

The sturgeon species are related to a food delicacy and are known for their rich nutritive properties that are essential for human health since prehistoric times. The intensive decline in wild sturgeon populations has led to an increase of the farmed and hybrid species in aquaculture production. The sturgeon meat contains highly digestible proteins, fats, vitamins and minerals which are influenced by its biodiversity. This review will provide different analytical techniques used for the determination of the quality and authenticity of sturgeon species. To attain these objectives, targeted techniques (chemical, sensory, microbiological, chromatographic, morphological, polymerase chain reaction, and so on) and untargeted ones (Fluorescence, and mid-infrared spectroscopies, and so on). The former techniques considered as the official methods used to assess the quality and authenticity of sturgeon are timeconsuming and need a trained personnel team, while the latter ones based on the use of fluorescence and mid-infrared spectroscopies are considered rapid, non-destructive, relatively cheap, and environmentally friendly. The use of untargeted techniques as a promising tool is not fully explored in the fish sector, particularly for sturgeon, which needs future research to demonstrate and prove their robustness for the determination of the quality and authenticity of this fish species.

Introduction

The family sturgeon (Acipenseridae) refers to a valuable fish in the sphere of commerce, which population is rapidly declining due to several factors such as changes in river streams, construction of hydropower stations, illegal fishing, and other negative human activities [START_REF] Bronzi | Present and future sturgeon and caviar production and marketing: A global c overview[END_REF]. According to the International Union for Conservation of Nature, sturgeons are the group of fish that falls under the level of extinction (IUCN, 2018). The Acipenseriformes display the highest level of critically endangered species among all the other threatened animal breeds. A sharp decrease in the number of natural inhabitants of sturgeons gave birth to a new branch in aquaculture named commercial sturgeon farming (Ericksonet al. 2005;[START_REF] Litvak | The sturgeons (Family: Acipenseridae). Finfish Aquaculture Diversification[END_REF].

It is well known that the chemical composition of fish can vary according to several parameters such as species, body size, season, nutritional status, and so on [START_REF] Al-Reza | Effect of traditional fish processing methods on the proximate and microbiological characteristics of laubuka dadiburjori during storage at room temperature[END_REF]. The sturgeon fish components include essential amino acids, vitamins, minerals, phosphorus, potassium. Due to the presence of glutamic acid, the sturgeon flesh tastes delicious [START_REF] Kaya | Fatty acid and amino acid composition of raw and hot smoked sturgeon (Huso huso, L. 1758)[END_REF]. Sturgeon meat has some of the long chains omega-3 fatty acids, including eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) [START_REF] Pelic | Fatty acid composition of Acipenseridae -Sturgeon fish[END_REF]. Omega-3 deficiency is associated with lower intelligence, depression, heart disease, arthritis, cancer, and many other health problems. Moreover, fish items with their high level of unsaturated fatty acids are essential for human health. Consequently, human consumption of sturgeon affects positively people's blood pressure, metabolic process, skin regeneration, and so on. Besides, this species of fish is considered to be dietary as sturgeon possesses low-calorie rates preserving high energy values due to its rapid digestibility [START_REF] Ghomi | Omega-6/omega-3 essential fatty acid ratio in cultured beluga sturgeon[END_REF].

According to [START_REF] Bronzi | Sturgeon meat and caviar production: Global update 2017[END_REF], the world's production of sturgeon biomass has increased within the last decade and reached the world 102.327 tons by 2017. As a result of fish hunting, the sturgeon production in the China Republic reached ~ 79.6 tons in 2017 representing 78% of the global series rate. Russia's production represents ~ 6.8 tons which makes 6.6% of the global rates. Sturgeon species showed a growing tendency around the world due to their oxygen tolerance and rapid adaptation to different farming systems. These species are promising candidates for aquaculture due to their excellent characteristics such as easy adaptation to a farming environment as well as their expensive caviar and dense meat. In 2016, the commercial sturgeon farming data, for different sturgeon species, reveal that there are 12 pure species and six hybrid items among the analysed 25 species of Acipenseridae showing a major share in the fish production. The main species include the Russian sturgeon (Acipenser gueldenstaedtii), Beluga sturgeon (Huso huso), Sterlet sturgeon (Acipenser ruthenus), White sturgeon (Acipenser transmontanus), Persian sturgeon (Acipenser persicus), and some hybrids (Figure 1). By 2017, about 2329 commercial sturgeon farms have appeared in the world, which represents an increase of 7% compared to 2016 [START_REF] Bronzi | Sturgeon meat and caviar production: Global update 2017[END_REF].

There are very few publications that are devoted to study sturgeon in the following topics: aquaculture, fisheries, freshwater biology, environmental sciences, ecology, biochemistry, and molecular biology [START_REF] Jarić | Modelling attempts utilized in sturgeon research: A review of the state-of-the art[END_REF].

Research related to aquaculture, in particular, sturgeon reproduction was among the central objects of the research. The genetic research, especially the use of DNA analysis, is becoming increasingly popular and had the highest impact. Previously, limited number of research in food industry was noted. Nevertheless, considering the current trend in output, it is very likely that the most countries will surpass this sector within the next 5-10 years.

The sturgeon fish tissue consists of a complex combination of organic compoundsproteins, fats, carbohydrates, water, minerals, and vitamin compounds. These substances are easily split by digestive enzymes or the microorganisms' fermentation (Ghaly, Dave, Budge, & Brooks 2010). Consequently, during storage, the fish lacks its nutritional values and becomes inappropriate for consumption, and even acquires toxic characteristics. The spoilage of sturgeon could be attributed to the growth of microorganisms [START_REF] Lougovois | Freshness quality and spoilage of chill-stored fish[END_REF]. Consequently, to preserve the quality of sturgeon and extend its shelf-life, different techniques including refrigeration, frosting, freezing [START_REF] Hosseini | Influence of the in vivo addition of alpha-tocopheryl acetate with three lipid sources on the lipid oxidation and fatty acid composition of Beluga sturgeon, Huso huso, during frozen storage[END_REF]Rostamzad, Shabanpour, Kashaninejad, & Shabani, 2011), vacuum packaging, modified atmosphere packaging (Yue-wen Chen et al., 2020), enzyme inactivation by natural compounds like salting, smoking, plant solution rich in natural antioxidants, and so on were applied [START_REF] Oliveira | Composition and Consumer Attribute Analysis of Smoked Fillets of Gulf Sturgeon ( Ancipenser oxyrinchus desotoi ) Fed Different Commercial Diets[END_REF]Sarah, Hadiseh, Gholamhossein, & Bahareh, 2010).

The quality of the sturgeon species could be determined by traditional techniques.

Among them, physico-chemical analyses comprising the determination of total volatile nitrogen, lipid oxidation products such as thiobarbituric acid reactive substances (TBARS) and peroxide value (PV) are commonly used as indicators of fish freshness [START_REF] Manju | Effects of sodium acetate dip treatment and vacuum-packaging on chemical, microbiological, textural and sensory changes of Pearlspot (Etroplus suratensis) during chill storage[END_REF]. The sensory properties are performed by the perceptible function of the human senses (colour, odour, flavour, texture, and taste) of raw and cooked fish muscles [START_REF] García | Smart sensor to predict retail fresh fish quality under ice storage[END_REF].

Although the ability of the physico-chemical, sensory, and microbiology methods is indisputable to determine the quality and authenticity of fish and fish products, the majority of them are considered to be relatively expensive, long-lasting, and time-consuming. Recently, an effort is devoted to the investigation of non-invasive and non-destructive instrumental methods such as infrared, and fluorescence spectroscopies among others. These techniques are considered to be rapid, relatively cheap, and environmentally friendly and can be carried out even by minimally trained personnel. They give a significant amount of information based on a single test. Moreover, spectroscopic techniques do not need much preparation of samples and in some cases can be held without any preparation [START_REF] Karoui | Front face fluorescence spectroscopy enables rapid differentiation of fresh and frozen-thawed sea bass (Dicentrarchus labrax) fillets[END_REF]. This present review paper will provide a comprehensive overview of the application of different analytical techniques, in combination with multivariate data analysis, to determine the quality of sturgeon quality. A layout of the review theme is outlined in Figure 2.

Targeted methods used for the determination of the quality and authenticity of sturgeon

In general, fish quality refers to the visual appearance and freshness which depends on the spoilage level. The fish quality also refers to safety aspects such as the absence of the pathogenic microorganisms, parasites and/or toxic elements. The methods used for the evaluation of the fish quality and its freshness include physico-chemical, microbiological, sensory analyses, and so on.

Physico-chemical analysis

After death, the quality of fish deteriorates because of the post-mortem changes. The alteration processes are always accompanied by (bio)chemical reactions that induce the formation of volatile and biogenic amines and changes in the pH, water content, cooking loss, peroxide value, and others. Table 1 shows a few studies that explored the use of physicochemical methods to assess the quality of sturgeon species. Undoubtedly, the proximate analysis is important for obtaining nutritional values of different sturgeon species which depends on the muscle composition that is observed in tissue quality parameters [START_REF] Hosseini | Influence of the in vivo addition of alpha-tocopheryl acetate with three lipid sources on the lipid oxidation and fatty acid composition of Beluga sturgeon, Huso huso, during frozen storage[END_REF]. Recently, [START_REF] Pelic | Fatty acid composition of Acipenseridae -Sturgeon fish[END_REF] determined a negative correlation between lipid level and water content of sturgeon meat.

Total volatile basic amines (TVB-N) is one of the most widely used parameters of fish quality. This general term includes the measurement of trimethylamine produced by spoilage bacteria, dimethylamine produced by autolytic enzymes, and other volatile basic nitrogenous compounds associated with seafood spoilage. Although the determination of TVB-N is simple, it only reflects the later stage of advanced spoilage that is generally considered insignificant for the measurements of spoilage during the first days of chilled storage. A level of 25 mg TVB-N/ 100 g of fish is considered to be the upper limit above which the seafood product is considered spoilt and unfit for human consumption [START_REF] Boughattas | Targeted and untargeted techniques coupled with chemometric tools for the evaluation of sturgeon (Acipenser gueldenstaedtii) freshness during storage at 4 °C[END_REF]. Meanwhile, there are differences in the published data disclosing the amount of TVB-N in fish tissue which seems to vary among fish species.

According to Chen et al. (2020) and [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF], the TVB-N values show the tendency to increase gradually during the storage of Russian sturgeon (A. gueldenstaedtii) and Beluga sturgeon (H. huso) and attained limit for human consumption on days 12 and 7, respectively. Other authors report that the permissible limit of TVB-N for human consumption is up to 8-9 days of storage at 4 °C for both Beluga and Russian sturgeon [START_REF] Bahram | Effect of whey Protein Concentrate Coating Cinamon Oil on Quality and Shelf Life of Refrigerated Beluga Sturegeon (Huso huso)[END_REF][START_REF] Boughattas | Targeted and untargeted techniques coupled with chemometric tools for the evaluation of sturgeon (Acipenser gueldenstaedtii) freshness during storage at 4 °C[END_REF].

The trimethylamine nitrogen (TMA-N), which is a volatile amine, might be considered as another parameter used to determine the quality of sturgeon. The TMA-N is generally produced following the reduction of trimethylamine oxide (TMAO) by bacterial flora in fish [START_REF] Masniyom | Deterioration and shelf-life extension of fish and fishery products by modified atmosphere packaging[END_REF]. According to Ünal Şengör, Alakavuk, Tosun, & Ulusoy (2010), raw Beluga sturgeon showed 0.55 mg/100 g TMA-N values, while hot-smoked Beluga samples exhibited higher TMA-N level (2.63 mg/100 g). However, the TMA-N values did not exceed the upper limit of acceptability proposed by [START_REF] Khodanazary | Freshness assessment of shrimp Metapenaeus affinis by quality index method and estimation of its shelf life[END_REF] for fish and fish products that is fixed to 5 mg / 100g. Lipid measurements are recognised by many authors to be the most commonly used indicator for measuring the biochemical assessment of sturgeon quality (Table 1). The sturgeon family belongs to the fatty fish and the fat content varied according to the species, season, and feeding (Wedekind, 2002). The lipid content of different cultured sturgeon species varied from 5 to 10% [START_REF] Pelic | Fatty acid composition of Acipenseridae -Sturgeon fish[END_REF]. The highly unsaturated fatty acid found in fish lipid is very sensitive to oxidation. These compounds can be detected by chemical methods that are usually used to determine the oxidation level. The peroxide value (PV) measurements showed an increase during sturgeon storage at 4 °C regardless of the fish species. For Beluga fillets, the initial PV value is generally very low reaching its maximum (3.5 meq O2/Kg fat) on day 8 of storage [START_REF] Bahram | Effect of whey Protein Concentrate Coating Cinamon Oil on Quality and Shelf Life of Refrigerated Beluga Sturegeon (Huso huso)[END_REF]. Sarah, Hadiseh, Gholamhossein, & Bahareh (2010) pointed out in their investigations that the maximum PV was noted on day 8 of storage (8.06 meq oxygen/ kg lipid) for Persian sturgeon (A. persicus) and depended on the treatment conditions.

In the later stage of oxidation, the secondary oxidation products are usually present in the fish and fish products. They contain aldehydes, ketones, short-chain fatty acids, and other components, many of them possess a very unpleasant smell and taste, rancid and associated with oxidised fish lipids. Some of the secondary oxidation products react with thiobarbituric acid to form a pink-coloured product. In this context, the TBARS values were reported to be the most used indicator for the assessment of the quality of Beluga during storage. A significant increase (P<0.05) of TBARS values was observed on day 10 of storage since it attained 2.12-3.02 mg MDA/kg of fish, regardless of the storage conditions: refrigerated storage at 4 °C with/without jujube gum containing nettle essential oil [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF]. In the same context, Rostamzad et al., (2011) noted that TBARS values remained quite low for Persian sturgeon fillets kept in freezing storage for 3 months since their values do not exceed 2 mg MDA/kg of fish.

Russian sturgeon (A. gueldenstaedtii) and Beluga (H. huso) presented pH values of 6.32 and 6.58, respectively [START_REF] Bahram | Effect of whey Protein Concentrate Coating Cinamon Oil on Quality and Shelf Life of Refrigerated Beluga Sturegeon (Huso huso)[END_REF]Yue wen Chen et al., 2020). A slight increase of pH values was observed during storage (Table 1) since it reached values of 7.47 (Bester, Asow-Hybrid, Sibster). This increase is due to the decomposition of glycogen (Song et al., 2011), and the production of volatile basic components by microbial proteolysis (Goulas & Kontominas, 2005;Ocaño-Higuera et al., 2009). It should be kept in mind that the pH value is a function of the post-mortem evolution of the flesh, which is influenced by diet, season, and stress during the catch, initial state of microbial contamination (viral, bacterial, mycoses, protozoses, helminthiases). This pathophysiological state depends of the individual specimen and can occur as a result of human activity. The pH increase is dependent of the storage temperatures of fish. Indeed, the higher the storage temperature, the faster is the increase in pH values [START_REF] Abbas | A review on correlations between fish freshness and pH during cold storage[END_REF].

Water holding capacity (WHC) and cook loss (CL) of fish muscle may be used as indicators of fish quality. The WHC of muscle food is an important technological parameter that depends on heat-induced structural changes, sarcomere length, pH, ionic strength (Zell, Lyng, Cronin, & Morgan, 2010). The WHC in meat tissues is strongly related to myofibril proteins. The increase of expressible moisture is a sign of the reduction of the WHC. Wedekind (2002) noted that the approximate level of CL and WHC for sturgeon hybrids ranged between 26-31% and 62-69%, respectively. The authors noted that the WHC of muscle was fairly stable in Beluga fish. Moreover, the WHC tends to decrease gradually with the increase of the frozen storage time since it passed from 70% to 62% after 8 months of frozen storage. This could be explained by the fact that during the freezing-thawing process, the denaturation of protein could be occurred causing the loss of WHC [START_REF] Hosseini | Influence of the in vivo addition of alpha-tocopheryl acetate with three lipid sources on the lipid oxidation and fatty acid composition of Beluga sturgeon, Huso huso, during frozen storage[END_REF].

A gradual increase of CL values was noted during storage at 4 °C of Beluga sturgeon (H. huso) since it passed from 26.51% to 40.32% during 15 days of storage [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF].

Texture measurements

The texture of fish muscle is an important feature of both raw and cooked sturgeon quality that depends on several parameters such as hardness, cohesiveness, springiness, chewiness, resilience, and adhesiveness, as well as the internal cross-linking of connective tissues. The change in texture of fish depends on internal factors such as chemical decompositions (lipid oxidation) and degradation of muscle proteins and some external factors, such as sample handling (salting and smoking) and cold storage conditions (freezing and thawing). Texture can be determined by instrumental technique that performs an accurate subjective assessment. The most used one is named texture profile analysis (TPA) which evaluates fish texture based on compression of a sturgeon sample with the TA. XTPlus texture analyser. The softening processes of sturgeon muscles happen either as a result of frozen/cold storage, or autolytic degradation [START_REF] Cheng | Texture and structure measurements and analyses for evaluation of fish and fillet freshness quality: A review[END_REF]. [START_REF] Boughattas | Targeted and untargeted techniques coupled with chemometric tools for the evaluation of sturgeon (Acipenser gueldenstaedtii) freshness during storage at 4 °C[END_REF] noted that texture parameters (hardness, adhesiveness, gumminess, chewiness) showed a significant difference (P < 0.05) between fresh sturgeon samples aged 2 days from those aged 8 days or more. However, springiness and cohesiveness parameters remained relatively stable during storage. In another study, [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF] indicated that the hardness decreased during Beluga sturgeon on day 7 of storage at 4°C. Indeed, the fresh samples and those aged 7 days presented hardness values of 17.32 and 11.08, respectively.

The external quality criteria such as changes in springiness was determined for Russian Sturgeon fillets kept in vacuum packaging and treated with different salt concentrations (Chen et al., 2020). The level of springiness was low for the samples treated with 2% salt solution and increased with salt concentration. However, the highest parameter of springiness was observed for control (no treatment) and those kept in vacuum packaging on day 0. In general, during the post-mortem condition, the muscle of fish get soft.

Colorimetric measurement

Fish tissue gradually turns to pale during storage; this change depends on different storage conditions, as a result of which some pigments are destroyed. There are various methods to measure the colour of sturgeon such as machine vision system that produces significant information about colour attributes. Electronic measurement devices define colour in terms of a* (red/green), b* (yellow/blue) and L* (black/white) values. As far as the L* value is concerned, no significant difference (P > 0.05) was observed between sturgeon samples kept at 4 °C for up to 12 days. The obtained results indicate that L* parameter is not affected through the storage time, while b* value increased gradually during the storage time of Russian sturgeon since it passed from 5.20 to 9.95 on days 2 and 9, respectively [START_REF] Boughattas | Targeted and untargeted techniques coupled with chemometric tools for the evaluation of sturgeon (Acipenser gueldenstaedtii) freshness during storage at 4 °C[END_REF]. However, the lightness (L* value) increased (P < 0.05) during 15 days of cold storage of Beluga sturgeon. This increase might be related to the degradation of myofibrillar proteins and disorganization of the myofibrils [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF]. The colour of three cultured sturgeon hybrids determined by Wedekind ( 2002) was found to be dependent of the measurement part inside the same fillet. Indeed, a more whitish colour in the cranial, a more reddish in the medial area and yellowish flesh in the caudal of the fillet was observed. The technological process induced changes in the colour of sturgeon flesh since Ünal Şengör et al. ( 2010) observed a higher value of a * for smoked sturgeon flesh (6.75) in comparison to raw sturgeon meat (0.63).

Sensory analysis

The appearance, odour, taste, colour, and texture are evaluated using the human senses. The sensory measurements that apply to sturgeon quality control can be divided into two main groups: tests that determine the differences between sturgeon samples (triangle test, ranking test) and tests that permit to distinguish the gradual alteration of sturgeon samples and they are relatively quick. The diversity in sensory response is related to the difference in sensitivity of receptors to chemical stimuli. For example, the rancid flavour is not perceptible by everyone. [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF] studied the quality of Beluga sturgeon with different analytical techniques including sensory one. The authors showed in their study that the panellists' scores diminished significantly (P < 0.05) with the increase of storage time that passed from 5 to 3.16, in agreement with the findings of [START_REF] Bahram | Effect of whey Protein Concentrate Coating Cinamon Oil on Quality and Shelf Life of Refrigerated Beluga Sturegeon (Huso huso)[END_REF] who noticed that sensory properties (colour, odour, texture) of Beluga sturgeon decreased with the increase of storage time. The sturgeon samples reached a limit score on days 8 since Beluga sturgeon fillets revealed a slimy rancid odour with discoloration (Table 2). The results of sensory evaluation of Persian sturgeon (A. persicus) during 8 days of storage at 4°C showed the emergence of rancid odour within the increased storage time. Some differences were depicted by Sarah et al. ( 2010) on days 6 for colour, odour, and flavour of Persian sturgeon stored at 4 ºC. A sharp increase of off-flavour was detectable in control samples and dipping solution of 1% onion juice. By the end of storage time, samples dipped in solution with 1% of onion juice and 1% of green tea extract as well as the control ones showed the lowest flavour scores, while those treated with the upper concentrations of plant extracts (2.5-5 % of onion juice and 2.5-5 % of green tea extract) indicated the highest flavour scores. Recently, Chen et al. (2020) explored the impact of vacuum packaging on the shelf-life of the Russian sturgeon and depicted that the shelf-life of the control group was 7 days, while those treated with salt and kept in vacuum packaging were fixed to 16 days.

Microbiological analysis

Microbiological analysis is used to assess the availability of microorganisms in the sturgeon fish. Traditional bacteriological examinations are laborious, time-consuming, expensive, and required skilled operators. Consequently, the most frequently used measurements include the determination of total viable counts (TVC) and psychrotrophic counts (PTC) (Table 3). A wide variety of microorganisms was observed during the storage of Beluga sturgeon fillets preserved with nettle essential oil. A gradual increase in the amount of PTC was scored during 15 days of storage at 4 °C. The treated samples presented a low amount compared to the control one [START_REF] Gharibzahedi | Effect of novel bioactive edible coatings based on jujube gum and nettle oil-loaded nanoemulsions on the shelf-life of Beluga sturgeon fillets[END_REF]. Based on the level of TVC and PTC, the maximum acceptable level of the raw Beluga sturgeon was fixed to 7 days of storage. However, based on microbiological analysis, samples showed a low level of microorganisms involved in extracts and solutions of plants during the entire storage period. The obtained results are in agreement with the findings of [START_REF] Bahram | Effect of whey Protein Concentrate Coating Cinamon Oil on Quality and Shelf Life of Refrigerated Beluga Sturegeon (Huso huso)[END_REF] who stated that the addition of essential oil into whey protein coating for Beluga sturgeon samples strongly inhibited the growth of TVC and PTC up to 20 days. Recently, Yue-wen Chen et al.

(2020) applied DNA analysis for the amplification of the microflora of the Russian sturgeon (A. gueldenstaedtii). The composition of microbiota was obtained by using the PCR method.

The results showed a relative abundance of 20 top genera (Chryseobacterium, Acinetobacter, Serratia, Pseudomonas, Salmonella) within different periods of cold sturgeon storage. The bacterial diversity decreased with storage time, while their number increased. The combination of salting and vacuum packaging was found to delay efficiently the growth of Pseudomonas which is the predominant microbiota found in the Russian sturgeon fillets (Yue wen Chen et al., 2020).

Chromatographic analysis

Chromatographic techniques used for the determination of sturgeon quality are carried out by using liquid and/or gas chromatography. These methods are used to determine the amino acid and fatty acid composition of sturgeon fish. The separation of components is performed with the help of chromatographic techniques in which every component is processed at a different rate in a two-phase system [START_REF] Jalali-Heravi | Characterization and determination of fatty acids in fish oil using gas chromatography -mass spectrometry coupled with chemometric resolution techniques[END_REF]Tucker, & Pigott, 2003). [START_REF] Hosseini | Influence of the in vivo addition of alpha-tocopheryl acetate with three lipid sources on the lipid oxidation and fatty acid composition of Beluga sturgeon, Huso huso, during frozen storage[END_REF] pointed out that frozen storage mode negatively affected the fatty acid composition of Beluga sturgeon (H. huso). Fish muscles aged 12 months presented higher concentrations of total saturated fatty acids compared to fresh ones.

The monounsaturated fatty acids levels of the fillets were similar during the 12 months of storage (P > 0.05). The n-3/n-6 ratio of Beluga sturgeon samples presented the highest level on day 0 and the lowest one on month 12 (P < 0.05). The eicosapentaenoic acid and docosahexaenoic acid levels decreased significantly from day 0 to month 12 (P < 0.05). [START_REF] Kaya | Fatty acid and amino acid composition of raw and hot smoked sturgeon (Huso huso, L. 1758)[END_REF] depicted that hot temperature and wood smoke affected negatively the fatty acid composition, especially EPA, DHA, and some essential amino acids in the smoking process (Table 4). In a different approach, Vaccaro et al. (2005) indicated that in sturgeon hybrid, the levels of polyunsaturated fatty acids (PUFAs) is very high (34.7 %) as well as the monounsaturated fatty acids (37.9%). These hybrid species (Acipenser naccarii × A. baerii) contained high contents of EPA (C20:5n3) and DHA (C22:6n3). [START_REF] Nieminen | Fatty acid composition in tissues of the farmed Siberian sturgeon (Acipenser baerii)[END_REF] found that the nutritional value of the farmed Siberian sturgeon (Acipenser baerii) in regard to their fatty acid composition, is quite similar to other sturgeon species. The Siberian sturgeon was found to accumulate highly unsaturated fatty acids selectively in particular tissues, using either the incorporation of these fatty acids from dietary sources or the desaturation and elongation of PUFA in its tissues.

Polymerase chain reaction

The authentication of fish species is necessary to be able to assure consumers of accurate labelling and maintain confidence in their quality and safety. DNA-analysis by polymerase chain reaction (PCR) method was used to identify fish species [START_REF] Hisar | Authentication of fish species using a simple PCR-RFLP method[END_REF]. This technique contributed to better, more reliable, regulation and control of global trade of high value sturgeon products as well as to their management and conservation. The DNA-markers, as compared with the biochemical methods, possess several advantages. Indeed, to use of DNA fragments as markers solved a number of tasks related to the identification of the sturgeon species [START_REF] Kuz'min | Polymorphism of the myogens locus in some representatives of sturgeons (Acipenseridae)[END_REF]. In the study of [START_REF] Albayrak | Characterization of GnRH, ILGFRI and AR Genes in Sturgeon's Genomics[END_REF] PCR analysis and DNA sequencing were used on Beluga sturgeon, Russian sturgeon and Sevruga the gonadotropin-releasing hormone (GnRH), insulin-like growth factor receptor I (ILGFRI), and androgen receptor (AR) genes coding and compared to reference Beluga sturgeon genome retrieved from database. The most similarity was calculated for AR gene and GnRH gene ranged from 48.5-95.71% and 23.48-83.91%, respectively, between the three species. A sample seized from poachers was found to be more like to Russian sturgeon samples (Table 5). These findings indicated a high level of diversity among and even within the same family. The authors depicted that the three genes could be useful for the identification of sturgeon species. The genetic polymorphism of ten sturgeon species (Russian sturgeon, Siberian sturgeon, Amur sturgeon, Sakhalin sturgeon, Persian sturgeon, Ship sturgeon, Sterlet, Sevruga sturgeon, Beluga sturgeon, and Kaluga sturgeon) was examined at five microsatellite loci (Afug41, Afug51, An20, AoxD161, AoxD165) in the investigation of [START_REF] Barmintseva | The use of microsatellite loci for identification of sturgeon species (Acipenseridae) and hybrid forms[END_REF]. Alleles specific to different species was identified.

Five microsatellite markers were analysed and their alleles were sequenced for the Adriatic sturgeon (Acipenser naccarii), the Atlantic sturgeon (Acipenser oxyrinchus) and the European sturgeon (Acipenser sturio) by [START_REF] Chassaing | Distinguishing species of European sturgeons Acipenser spp. using microsatellite allele sequences[END_REF]. Fixed mutations in the flanking regions or in the core repeat of microsatellites provided a clear distinction between the sturgeon species. These nuclear markers combined with mitochondrial markers was found to be used to identify hybridisation among the three species. [START_REF] Boscari | Fast genetic identification of the Beluga sturgeon and its sought-after caviar to stem illegal trade[END_REF] developed the first genetic nuclear marker for the identification of the Beluga sturgeon (Huso huso). The interspecific variability at the second predicted intron of the RPS6 nuclear ribosomal gene was found to be a suitable marker for the identification of the Beluga sturgeon. The diagnostic nuclear marker characterised allowed the identification of pure Beluga and its first generation hybrids. In a similar approach, nuclear DNA markers was applied for the identification of Beluga sturgeon and Sterlet, and their Bester sturgeon hybrid [START_REF] Havelka | Nuclear DNA markers for identification of Beluga and Sterlet sturgeons and their interspecific Bester hybrid[END_REF]. The authors employed double-digest restriction-associated DNA (ddRAD) sequencing to identify species-specific nucleotide variants, which were served as specific binding sites for diagnostic primers. The primers allowed the identification of Beluga sturgeon and Sterlet as well as their discrimination from other sturgeon species. The species-specific primers allowed the identification of Bester sturgeon (H. huso × A. ruthenus). Another two sister species of Atlantic sturgeon and European sturgeon were found to be difficult to distinguish solely by morphological traits [START_REF] Panagiotopoulou | A PCR-RFLP based test for distinguishing European and Atlantic sturgeons[END_REF]. A simple PCR-restriction fragment length polymorphism based test was developed, enabling easy identification of specimens belonging to both species. The application of two restriction enzymes (BtsI and BsrDI) allowed a clear discrimination of 132 specimens of European sturgeon and Atlantic sturgeon (Table 5).

Morphological methods

Morphological analysis of sturgeons have a very long history and have been carried

out to identify sturgeon species [START_REF] Ludwig | Identification of acipenseriformes species in trade[END_REF]. However, authentication of sturgeon species based on morphological traits are scarce in the literature. Descriptive morphology allows to distinguish sturgeon by external features. Sturgeons as a like most other fish, have a body comprised of three regions: head, body, and fins. Each of these regions is characterised by a number of specialised adaptations -some typical of all sturgeons while others are species specific. These sometimes subtle morphological variations are used to identify different sturgeon species or, in some cases, to identify different populations within a species. The main diagnostic characters of these family Acipenserinae including the genera Acipenser and Huso are the shape of the mouth and differences in gill-membrane attachment (Vasil'eva, 2009). The rostrum used in ecomorphological measurements as a criteria relating to flow and/or feeding methods. Spiracle is open above the gills in Huso and Acipenser and absent in Scaphirhynchus and Pseudoscaphirhynchus. Thick lips surround the mouth and the upper lip is interrupted in all species except Ship sturgeon (A. nudiventris). The sturgeon mouth is unique in lacking a jaw bone, and the mouth is capable of extensive downward and outward projection. Mouth dimensions in sturgeon are often used in ecomorphological analyses. In proportion to body size, the smallest mouth occurs in the Atlantic sturgeon (Acipenser transmontanus) that feeds primarily on bryozoans and small invertebrates, in contrast, white sturgeon (Acipenser transmontanus) has the largest mouth (Vecsei & Peterson, 2004).

Untargeted methods used for the determination of the quality of sturgeon

Untargeted tools such as spectroscopic techniques have the advantage to be fast, lowcost, and non-destructive to a large extent. The techniques have demonstrated their ability to determine the quality and authenticity of fish [START_REF] Hassoun | Monitoring changes in whiting (Merlangius merlangus) fillets stored under modified atmosphere packaging by front face fluorescence spectroscopy and instrumental techniques[END_REF]2017;Karoui and Hassoun, 2017), dairy products [START_REF] Blecker | Effect of heat treatment of rennet skim milk induced coagulation on the rheological properties and molecular structure determined by synchronous fluorescence spectroscopy and turbiscan[END_REF]Karoui et al., 2006;[START_REF] Karoui | Mid infrared and fluorescence spectroscopies coupled with factorial discriminant analysis technique to identify sheep milk from different feeding systems[END_REF], egg [START_REF] Karoui | Front face fluorescence spectroscopy as a tool for the assessment of egg freshness during storage at a temperature of 12.2 °C and relative humidity of 87%[END_REF][START_REF] Ludwig | Identification of acipenseriformes species in trade[END_REF], and so on.

Fluorescence spectroscopy

Although the interest of this technique, only very few studies have explored the potential of fluorescence spectroscopy to determine the quality of sturgeon. Sturgeon fish contains several fluorophores, including aromatic amino acids and nucleic acids (AAA+NA), tryptophan, vitamins A, riboflavin, nicotinamide adenine dinucleotide (NADH), and many other compounds that can be detected in minimal concentrations. In this context, [START_REF] Boughattas | Targeted and untargeted techniques coupled with chemometric tools for the evaluation of sturgeon (Acipenser gueldenstaedtii) freshness during storage at 4 °C[END_REF] monitored the freshness level of Russian sturgeon (A. gueldenstaedtii) during storage at 4 °C. The emission spectra of riboflavin (405-650 nm) and NADH (360-600 nm) of sturgeon slices were acquired after excitation set at 380 and 340 nm, respectively. The maximum fluorescence intensity of riboflavin spectra is observed within ~ 460-490 nm that changed with the storage time. The observed peak was ascribed to different stable fluorescent oxidation products, which include the products formed by the reaction of unsaturated aldehydes with proteins and/or the photo breakdown of riboflavin products. The NADH spectra indicated several peaks located ~ 380, 460, and 485 nm. The authors concluded that the shape of NADH spectra was correlated with the freshness level of sturgeon samples. In fact, a decrease (~ 460 and 485 nm) and an increase (~ 380 nm) in the fluorescence intensity of sturgeon samples were noted during storage. A sharp decrease of the fluorescence intensity ~460 and 485 nm was ascribed by the authors to the NADH oxidation occurring during the sturgeon storage leading to the transformation of NADH to NAD+, and thus modifying the shape of the NADH fluorescence spectra. One of the main conclusions of their study was that NADH spectra could be used as fingerprints allowing to identify the level of sturgeon freshness. This result was confirmed following the application of common components and specific weights analysis to the riboflavin and NADH data tables since four groups were identified: 2 days; 5, 6 and 7 days; 8 and 9 days and 12 days. Another fluorophore namely AAA+NA was used for monitoring Russian sturgeon during cold storage. The AAA+NA emission spectra were recorded between 290 and 400 nm after excitation set at 250 nm [START_REF] Boughattas | Targeted and untargeted techniques coupled with chemometric tools for the evaluation of sturgeon (Acipenser gueldenstaedtii) freshness during storage at 4 °C[END_REF]. The authors observed that the maximum emission was observed ~ 375 nm and the shape of the spectra varied as a function of the storage time. The highest fluorescence intensity was noted for sturgeon samples aged 12 days, and the lowest one for those aged 2 days. This difference might be explained by the difference in the protein-protein, protein-water and/or protein-lipid interactions. Considering the vitamin A spectra, the shape of the spectra showed a maximum located ~ 296 nm for sturgeon aged 2 days and 310 for the aged ones. This red shift was attributed by the authors to the: i) physical states of the triglycerides in the fat globules; and/or ii) interactions of the fat globule membrane with protein network and/or lipid-lipid interactions.

In another way, fish authentication is important for correct product labelling as promoted by recent regulatory actions [START_REF] Ottavian | Foodstuff authentication from spectral data : Toward a species-independent discrimination between fresh and frozenthawed fish samples[END_REF]. In this context, the fluorescence spectroscopy was used to determine the impact of freeze-thaw cycles (1, 2, 3, and 4) on the quality of Russian sturgeon (Acipenser gueldenstaedtii) kept in a partial vacuum and a total vacuum (Vilkova, Chèné, Kondratenko, & Karoui, 2021). The NADH emission spectra scanned on sturgeon samples subjected to different freeze-thaw cycles illustrated two peaks located ~ 388 and ~ 470 nm. The highest fluorescence intensity at 388 nm was observed for fresh samples, while the highest fluorescence intensity at 470 nm was noted for those subjected to 4 freeze-thaw cycles kept in a partial vacuum (Vilkova, Chèné, Kondratenko, & Karoui, 2021). The vitamin A spectra demonstrated the highest fluorescence intensity ~ 296 nm for fresh samples and those submitted to 1 freeze-thaw cycle kept in partial vacuum and total vacuum. Moreover, a red shift of the maximum excitation spectra of vitamin A was observed (i.e., from 296 nm for samples subjected to 1 freeze-thaw cycle kept in a partial vacuum and total vacuum to 306 nm for those submitted to 2, 3, and 4 freeze-thaw cycles). The riboflavin spectra scanned on sturgeon samples showed two peaks ~ 468 nm and ~ 500 nm. Changes ~ 500 nm that were related to riboflavin degradation and/or interaction with other compounds such as proteins. The spectral range in the 405 -480 nm could be used to determine the degree of fish oxidation; among them, the products formed by the reaction of unsaturated aldehydes with proteins (Karoui et al., 2017). To extract information from the data sets, the authors applied the PCA separately to each intrinsic probe and the best results were obtained with the vitamin A and riboflavin spectra (Vilkova, Chèné, Kondratenko, & Karoui, 2021). Indeed, a clear differentiation between fresh sturgeon samples and those subjected to 1 freeze-thaw cycle from the others was observed. In addition, a separation between samples subjected to 2, 3, and 4 freeze-thaw cycles was also noted.

Mid infrared spectroscopy

Mid-infrared (MIR) spectroscopy is an established method used for protein and peptide structural characterisation. In this context, the technique was used for the characterisation of sturgeon by Jiang Zheng, Rue-Zhang Guan ( 2008 Recently, Noman, Ali, AL-Bukhaiti, Mahdi, & Xia (2020) used MIR spectroscopy to determine the quality of Chinese sturgeon (Acipenser sinensis). The spectra of the lyophilized protein hydrolysate samples were scanned in the 4.000 -500 cm -1 . The authors determined the absorbance in the Amide regions with protein hydrolysate samples which appeared at 1626 cm -1 (Amide I), 1511 cm -1 (Amide II), and 1388 cm -1 (Amide III) for papain hydrolysate sample, whereas the absorbance regions of alcalase hydrolysate samples occur at 1626 cm -1 (Amide I), 1518 cm -1 (Amide II), and 1388 cm -1 (Amide III). The liberation of peptides and free amino acids of complex protein-rich substrates depends on both the raw sturgeon quality and the enzymes used.

In a different approach, the potential of MIR to differentiate fresh Russian sturgeon samples from those subjected to 1, 2, 3, 4 freeze-thaw cycles was determined (Vilkova, Chèné, Kondratenko, & Karoui, 2021). Most of the spectral information was located in three wavenumber regions: 3000-2800 cm -1 , 1700-1500 cm -1 , and 1500-900 cm -1 . The 1500-900 cm -1 spectral region showed absorbance bands ~ 1083, 1118; 1158, 1239, 1314, 1371, 1396, 1418, and 1458 cm -1 . Fresh sturgeon samples exhibited two peaks ~ 1371 and 1418 cm -1 which disappeared for sturgeon samples subjected to freeze-thaw cycles. The peak located ~1418 cm -1 could be attributed to the combination of O-H bending of the C-O-H group and C-H bending of alkenes. The 1000-1200 cm -1 spectral region differentiated clearly between fresh samples and those subjected to 4 freeze-thaw cycles kept in partial and total vacuum.

The region located between 1700-1500 cm -1 showed two peaks (1547 and 1637 cm -1 ). The Amide I band (1600-1700 cm -1 ) is recognised as the most useful spectral region used to determinate the secondary structure of proteins [START_REF] Pinilla | Structural features of myofibrillar fish protein interacting with phosphatidylcholine liposomes[END_REF]. During the freeze-thaw cycle of sturgeon samples, protein is subjected to the oxidation leading to some variation of α-helix, β-sheet, β-turn, and random coil levels that have an absorption band in the 1650-1660 cm -1 , 1600-1640 cm -1 , 1660-1690 cm -1 and 1640-1650 cm -1 spectral regions, respectively. The percentage of the secondary structure indicated a decrease in α-helix, β-sheet, and random coil, and an increase in β -turn.

Indeed, an increase in β-turn (from 35.40% for fresh samples to 39.70 % and 37.06% for samples subjected to 4 freeze-thaw cycles kept in a partial vacuum and a total vacuum, respectively) and a decrease in α-helix (from 10.70% for fresh samples to 9.30 % and 9.23% for samples subjected to 4 freeze-thaw cycles kept in a partial vacuum and a total vacuum, respectively) were noted (Vilkova, Chèné, Kondratenko, & Karoui, 2021).

The region located between 3000 and 2800 cm -1 corresponds to C-H bond of methyl and methylene groups of fatty acids. This spectral region presented two bands ~ 2852 and 2925 cm -1 for fresh samples that disappeared during freeze-thaw cycles. Consequently, the potential use of MIR spectroscopy to rapidly identify commercial frauds in the fish sector and to solve some authentication was demonstrated (Vilkova, Chèné, Kondratenko, & Karoui, 2021).

Conclusion and future directions

Considerable interest is paid to sturgeon quality and authenticity due not only to its nutritive quality but also to the crises and scandals in the food industry, which have seriously undermined consumer confidence and grown the need for rapid analytical techniques to determine sturgeon quality and authenticity. This great need for quality assurance requires appropriate analytical tools for the determination of the quality of sturgeon samples. In this context, targeted methods such as -chemical, sensory, microbiological, chromatography techniques, morphological and PCR, considered as the official methods, were used to assess the quality and authenticity of the sturgeon. However, most of these methods are time consuming, destructive, and demand trained personnel. This requires the development of fast, environment-friendly and simple analytical techniques such as the spectroscopic ones that are relatively of low-cost and can be applied in both fundamental researches and the factory as on-line sensors for the determination of sturgeon quality. In this review, recent advances in sturgeon quality evaluation and authenticity by front-face fluorescence, and mid-infrared spectroscopies are presented and discussed. From the results presented in the present review, it could be mentioned that spectroscopic techniques coupled with chemometric tools have the potential to determine the quality and authenticity of sturgeon. Up-to-date, the use of these techniques alone and their combination of these spectroscopic techniques for the evaluation of the quality of sturgeon is scarce. Thus, the combination of untargeted techniques with targeted ones would make them more convenient and effective for the analysis of sturgeon allowing them to be used as rapid screening tools for determining rapidly the quality and authenticity of sturgeon. https://doi.org/10.1016/j.foodres. 2020.109687 Rostamzad, H., Shabanpour, B., Kashaninejad, M., & Shabani, A. (2011). Antioxidative activity of citric and ascorbic acids and their preventive effect on lipid oxidation in frozen persian sturgeon fillets. Latin American Applied Research, 41(2), 135-140. Sarah, H., Hadiseh, K., Gholamhossein, A., & Bahareh, S. (2010). Effect of green tea

List of Tables:

Table 1: Some examples of physico-chemical methods used for quality assessment of sturgeon species Table 2: Some examples of sensory methods used for quality assessment of sturgeon species Table 3: Some examples of microbiological analysis the used for quality assessment of sturgeon species Table 4: Some examples of chromatography methods used for quality assessment of sturgeon species Table 5: Some examples of polymerase chain reaction analysis used for authenticity of sturgeon species during frozen storage -WHC in the experimental fish was fairly stable and gradually decreased as the frozen storage time increased.

α-tocopheryl acetate did not affect lipid hydrolysis

  ). The results showed that sturgeon samples exhibited absorption at 1376 (-COO -), 1344 (-COOH, -C-O), 1310 (-COOH, -C-O), 1157 (C-O-C, C-O-H, C-O), 883 (C-H), and 856 (OSO3, C-O-S) cm -1 . The chondroitin sulfates of sturgeon contain 4, 6-disulfated chondroitin sulfates.

(Figure 1 :Figure 2 :

 12 Figure 1: Biodiversity of sturgeon species

Figure 1 Figure 2

 12 Figure 1

  were categorised to possess high quality characteristics with pH, total volatile base nitrogen (TVB-N), and trimethylamine nitrogen (TMA-N) values. -A decrease in L * value and increases in a * and b * values in the skin were determined; whereas all L * , a * , and b * values increased in the flesh shelf-life using edible active coatings. An increase in the values of WL, CL, PV, TBA, TVB-N, and pH

Table 4 :

 4 29 Fatty acid; EPA: Eicosapentaenoic acid; DHA: Docosahexaenoic acid; MUFA: monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids; SFA: 30 Saturated fatty acid; SSZ: The reciprocal hybrid of Siberian sturgeon with green sturgeon; HUFA: Highly unsaturated fatty acid 31

	Species of sturgeon	Methods/		Treatment of	Objectives	Main results	Reference
		parameters		samples
		Fatty	acid	Alpha-	To investigate the effects of	-The FA composition of the muscle underwent	Hosseini et al., 2010
		composition		tocopheryl	vitamin E on muscle fatty acid	slow changes during frozen storage. The EPA and
				acetate	composition of flesh during	DHA levels decreased significantly from day 0 to
					frozen storage	month 12.
						-The MUFA levels of the fillet were similar
						during the 12 months of storage The n-3/n-6 ratio
						of the fillet was the highest on day 0 and the
	Beluga sturgeon					lowest on month 12
	(Huso huso)	Fatty acid and amino	Hot smoking	To determine the effects of hot	The temperature and the wood smoke	Kaya, Turan, &
		acid composition		smoking on the fatty acid and	components in the smoking process negatively	Erdem, 2008
					amino acid composition	affect the fatty acid composition, especially EPA,
						DHA and some essential amino acids
		Fatty acid profile	-	To evaluate the changes in fatty	-The raw sample consists of 29.1 g/100 g	Nikoo, Benjakul, &
					acid composition of Beluga	saturated fatty acids (SFA), 42.554 g/100 g	Xu, 2015
					fillets	monounsaturated fatty acids (MUFA), and 28.126
						g/100 g polyunsaturated fatty acids (PUFAs).
						-In fried samples, levels of C18 fatty acid groups,
						MUFA, PUFA, and n6/n3 ratio increased while
						SFAs, EPA, and DHA content decreased. Upon
						chill storage, C18:2 fatty acid and n6/n3 ratio
						decreased while n3 fatty acids increased slightly
	White sturgeon	Fatty	acid	-	To determine the nutritional	-The fatty acid composition proved to be rather	Badiani et al., 1996
	(Acipenser	composition, Amino		composition of	high in the n-3 PUFA content and n -3/n -6 ratio.
	transmontanus),	acid composition		sturgeon flesh	Saturated, monounsaturated, and polyunsaturated
	Italian sturgeon					(PUFA) fatty acid contents were 1.76, 3.12, and
	(Acipenser naccarii)					1.46 g/100 g wet weight, respectively; n -3
	and Siberian					-PUFAs reached 1.18 g/100 g, whereas n -6
	sturgeon (Acipenser					PUFAs were 0.28 g/100 g. The n -3/n -6 ratio
	baeri)					was 4.23

Table 5 : 32 Species of sturgeon Methods/ parameters Treatment of samples Objectives Main results Reference

 5 The ILGFRI gene showed the most similar sequences (75.96-96.15%) for the 3 species. -Gene sequence similarity obtained for AR gene ranged from 48.5-95.71%.-The GnRH gene had more distant sequences (23.48-83.91%) between species.-There was similarity between H. huso samples and the reference H. huso samples.-An unauthorized (a sample seized from poachers) fish samples was more closely related to A. stellatus

	PCR analysis and	-	To examine three genes coding	-
	DNA sequencing		for	gonadotropin-releasing
			hormone (GnRH), insulin-like
	Beluga sturgeon		growth factor receptor I
	(Huso huso),		(ILGFRI), and androgen
	Sevruga (Acipenser		receptor (AR) of muscle tissue
	stellatus) and
	Russian sturgeon
	(Acipenser
	Gueldenstaedtii)

Acknowledgments:

This work has been carried out in the framework of ALIBIOTECH project, which is financed by the European Union, the French State and the French Region of Hauts-de-France. Mrs. D.

Vilkova is grateful to Vernadsky program for its financial support of her Ph.D. during her stay at Artois University.

Conflicts of interest:

The authors have declared that there is no conflict of interest.

Species of sturgeon Methods/ parameters

Treatment of samples

Objectives