This study investigated the effect of low-voltage electrostatic field on the flavor quality changes and generation pathways of refrigerated sturgeon caviar. Research has found that after storage for 3-6 weeks, the physicochemical properties of caviar in the LVEF treatment group are better than those in the control group. The results of two-dimensional gas chromatography-time-of-flight mass spectrometry showed that the contents of hexanal, nonanal, (E,Z)-2,6-nonadienal, (E)-2-octenal and 1-octene-3-one related to the characteristic flavor of caviar (sweet, fruity and green) increased significantly. The lipidomics results indicated that the effects of LVEF on caviar mainly involve glycerophospholipid metabolism, linoleic acid metabolism, and α-Linolenic acid metabolism. Methanophosphatidylcholine (15:0/18:1), phosphatidylcholine (18:0/20:5), and phosphatidylcholine (18,1e/22:6) were significantly correlated with odor formation. Therefore, low-voltage electrostatic field treatment preserved the quality and enhanced the flavor of sturgeon caviar. This study provided a new theoretical basis for the preservation of sturgeon caviar.

Sturgeons are ancient fish, with 27 species distributed in the Northern Hemisphere. This review first touches upon the significance of sturgeons in the context of their biological, ecological, and economic importance, highlighting their status as \"living fossils\" and the challenges they face in genomic research due to their diverse chromosome numbers. This review then discusses how omics technologies (genomics, transcriptomics, proteomics, and metabolomics) have been used in sturgeon research, which so far has only been done on Acipenser species. It focuses on metabolomics as a way to better understand how sturgeons work and how they react to their environment. Specific studies in sturgeon metabolomics are cited, showing how metabolomics has been used to investigate various aspects of sturgeon biology, such as growth, reproduction, stress responses, and nutrition. These studies demonstrate the potential of metabolomics in improving sturgeon aquaculture practices and conservation efforts. Overall, the review suggests that metabolomics, as a relatively new scientific tool, has the potential to enhance our understanding of sturgeon biology and aid in their conservation and sustainable aquaculture, contributing to global food security efforts.

The main objectives of this study were to determine the mercury concentration in four species of valuable and widely consumed fish from the Caspian Sea, to assess the health risk due to their consumption. The average mercury concentrations for Chelon saliens, Chelon auratus, Acipenser persicus and Acipenser stellatus were 32.72, 39.51, 166.87 and 81.87 μg g-1 dw, respectively. There were correlations between the mercury concentrations in the muscle of Chelon saliens and morphological parameters, but these correlations were not observed in Chelon auratus. Our comparison of the mercury values obtained in all the samples with the recommended international standards, as well as the Hazard Quotients values, indicated that there is no potential risk for the health of consumers due to exposure to mercury from consuming these fish.

White sturgeon Acipenser transmontanus is the primary species used for caviar and sturgeon meat production in the USA. An important pathogen of white sturgeon is acipenserid herpesvirus 2 (AciHV-2). In this study, 4 archived isolates from temporally discrete natural outbreaks spanning the past 30 yr were sequenced via Illumina and Oxford Nanopore Technologies platforms. Assemblies of approximately 134 kb were obtained for each isolate, and the putative ATPase subunit of the terminase gene was selected as a potential quantitative PCR (qPCR) target based on sequence conservation among AciHV-2 isolates and low sequence homology with other important viral pathogens. The qPCR was repeatable and reproducible, with a linear dynamic range covering 5 orders of magnitude, an efficiency of approximately 96%, an R2 of 0.9872, and an analytical sensitivity of 103 copies per reaction after 35 cycles. There was no cross-reaction with other known viruses or closely related sturgeon species, and no inhibition by sturgeon DNA. Clinical accuracy was assessed from white sturgeon juveniles exposed to AciHV-2 by immersion. Viral culture (gold standard) and qPCR were in complete agreement for both cell culture negative and cell culture positive samples, indicating that this assay has 100% relative accuracy compared to cell culture during an active outbreak. The availability of a whole-genome sequence for AciHV-2 and a highly specific and sensitive qPCR assay for detection of AciHV-2 in white sturgeon lays a foundation for further studies on host-pathogen interactions while providing a specific and rapid test for AciHV-2 in captive and wild populations.

Veronaea botryosa is the etiological agent of a systemic phaeohyphomycosis known as \"fluid belly\" in white sturgeon (Acipenser transmontanus). Fluid belly is a critical disease affecting sturgeon aquaculture and the caviar industry for which there are no commercially available vaccines or approved antifungal treatments to manage outbreaks. The primary aim of this study was to investigate the effect of a V. botryosa [conidia], a V. botryosa [mold], and a Saccharomyces cerevisiae [yeast] formalin-killed vaccine on sturgeon immune responses to fungal challenge. Immunization consisted of an initial intracoelomic injection with one of the three treatment preparations, followed by a vaccine booster four weeks later by the same route and dose. Experimental challenge by intramuscular injection with a virulent V. botryosa conidia suspension followed after another four weeks. Non-challenged control fish received injections of PBS. The inactivated vaccines proved safe for white sturgeon fingerlings. Sturgeon immunized with either V. botryosa [mold] or S. cerevisiae [yeast] exhibited a significantly different pro-inflammatory response upon challenge with V. botryosa compared to non-immunized fish. Challenged fish developed clinical signs similar to those reported during natural outbreaks of fluid belly. Positive control treatments (those not immunized but challenged with V. botryosa) experienced the highest mortality; however, survival curves were similar amongst all treatments (p < 0.05). Furthermore, the S. cerevisiae [yeast] vaccine resulted in comparatively lower fungal persistence and fewer lesions following histological analysis. Further efforts evaluating the potential of Saccharomyces spp. as a vaccine candidate against fluid belly are warranted.

Oxidative stress in the skin, induced by an unhealthy lifestyle and exposure to UVB radiation, leads to skin aging, including reduced elasticity, formation of wrinkles, moisture loss, and inflammation. In a previous study, we revealed the photoaging effects of enzyme-treated caviar extract (CV) by regulating collagen and hyaluronic acid synthase, melanogenesis, anti-oxidant mechanisms, and inflammation in a UVB irradiation-induced mice model. HPLC and MALDI-TOF were performed to determine the effect of enzyme treatment on the free amino acid contents and peptide molecular weight in supercritical caviar extract. As results of the analysis, CV is mainly composed of low-molecular-weight peptides consisting of leucine, tyrosine, and phenylalanine. Based on our in vitro and in vivo study, we conducted a clinical trial to assess the skin anti-aging efficacy of CV. In this randomized, double-blind, placebo-controlled trial, we measured indicators related to elasticity, wrinkles, and skin hydration at 4 and 8 weeks after consumption of CV. The subjects were categorized into caviar, combination, and placebo groups. After 4 weeks, skin hydration, dermal hydration, and transepidermal water loss all showed significant improvement. Furthermore, after 8 weeks, skin elasticity indexes-R2 (total elasticity), R5 (net elasticity), and R7 (ratio of elastic recovery to total deformation)-exhibited significant increases. Improvement in wrinkle indicators (Rmax, Ra, and Rz) and the whitening indicator melanin pigment was also observed. This is the first report showing that CV has significant skin anti-aging efficacy on human skin. In conclusion, our study suggests that CV can be used as skin anti-aging nutraceuticals through positive effects on skin condition in clinical trials.

This study aimed to explore the applicability of DNA barcoding for assessing the authenticity of caviar on the Chinese market. A set of universal COI primers and two sets of designed primers based on COI and D-loop genes were used to identify maternal species of samples from 21 batches of caviar. The results showed that the PCR products from three sets of primers had more than 98% similarity to the sequences in database. The COI gene could not distinguish sturgeons with closed genetic relationships, while D-loop gene could effectively improve the accuracy of DNA barcoding and was more suitable to the identification of interspecific sturgeon than the COI gene. The neighbor-joining dendrogram further confirmed the applicability and accuracy of COI and D-loop genes in identifying maternal relatives of caviar (Acipenser baerii/Acipenser gueldenstaedtii/Acipenser schrenckii/Huso dauricus/Huso huso). Despite the limitations of mitochondrial DNA in identifying hybrid sturgeon species, the presence of counterfeit caviar of non-sturgeon ingredients could be excluded. All the caviar samples were identified successfully as sturgeon species, but the mislabeling rate of species was 33.4%, indicating that there were illegal phenomena such as disorderly labeling, mislabeling, and adulteration on the market.

This study investigated anti-melanogenesis effects of enzyme-treated caviar extract (CV) in murine melanoma B16F10 cells and SKH-1 hairless mice. To induce melanin production in vitro and in vivo studies, B16F10 cells were treated with 3-Isobutyl-1-methylxanthine (IBMX), and SKH-1 hairless mice were irradiated with UVB, respectively. The expression of melnogenesis-related factors and signaling molecules were analyzed by ELISA and western blotting. 50, 100 and 200 μg/mL of CV significantly decreased the melanin contents and the activities of tyrosinase, nitric oxide, glutathione, and cAMP, melanogenesis factor, in B16F10 cells treated IBMX. In addition, CV significantly suppressed the expression of melanogenesis proteins such as pPKA, pCREB, MITF, TRP-1and TRP-2. Similarly, results of oral administration of CV (20, 50 and 100 mg/kg) for 8 weeks in UVB-Induced SKH-1 hairless mice, the expression of melanogenesis-related factor tyrosinase, nitric oxide, and cAMP and protein expression of pPKA, pCREBa, MITF, TRP-1and TRP-2 was significantly reduced. In particular, 100 mg/kg of CV exhibited an excellent effect similar to control group. Therefore, we suggest the possibility of developing CV as a food supplement having skin whitening effects by ameliorating melanogenesis.

Significant differences in the fatty acid (FA) composition of caviar and muscle tissue (fillet) were found in the sterlet Acipenser ruthenus (Linnaeus, 1758) between fish from the Yenisei River and aquaculture farms and were associated with different food sources. Caviar and muscle tissue of sterlet from the natural habitat showed significantly higher levels of the FAs that provide biomarkers of diatoms and bacterial matter. Oleic and linoleic acids, which are characteristic of higher plant oils, and long-chain monounsaturated fatty acids, which are biomarkers of marine copepods, displayed significantly higher contents in sterlet grown in aquaculture, apparently originating from artificial foods. A ratio of several biomarker FAs was for the first time proposed to assay, and its threshold value was established to determine whether sturgeon caviar and fillet originate from fish from natural habitats or aquaculture.

The outbreak of the COVID-19 pandemic significantly negatively impacted the global economy and stock markets. This paper investigates the stock-market tail risks caused by the COVID-19 pandemic and how the pandemic affects the risk correlations among the stock markets worldwide. The conditional autoregressive value at risk (CAViaR) model is used to measure the tail risks of 28 selected stock markets. Furthermore, risk correlation networks are constructed to describe the risk correlations among stock markets during different periods. Through dynamic analysis of the risk correlations, the influence of the COVID-19 pandemic on stock markets worldwide is examined quantitatively. The results show the following: (i) The COVID-19 pandemic has caused significant tail risks in stock markets in most countries, while the stock markets of a few countries have been unaffected by the pandemic. (ii) The topology of risk correlation networks has become denser during the COVID-19 pandemic. The impact of the COVID-19 pandemic makes it easier for risk to transfer among stock markets. (iii) The increase in the closeness of the risk relationship between countries with lower economic correlation has become much higher than that between counties with higher economic correlation during the COVID-19 pandemic. For researchers and policy-makers, these findings reveal practical implications of the risk correlations among stock markets.