Quality Changes in the Adductor Muscle of Ezo Giant Scallop Mizuhopecten yessoensis (Jay, 1857) During Refrigerated Storage

Recently, the popularity of scallops consumption and the preference to eat them raw have been increasing worldwide. Therefore, maintaining its freshness and quality is important. It is necessary to investigate the changes in quality, particularly umami-related component parameters and perform a comprehensive evaluation to assess scallop quality over time. In this study, the distinction in the abundance of microorganisms, K value, pH, color value, glycogen content, and ATP-related compound levels (i.e., ATP, ADP, AMP, IMP, HxR, Hx, and glutamic acid levels) were investigated to determine the quality of Ezo giant scallops. The parameters were evaluated every day for six days at 4°C post mortem of the scallops. The total viable aerobic count of marine bacteria increased from 1 to 3 log CFU/g over six days, and the K value increased sharply from 18% on day 2 to 66% on day 4. The pH decreased from 7.0 on day 0 to 6.0 on day 3, but the color value did not change during the six days of observation. The AMP content increased over three days and then decreased during the last three days of storage. IMP was not detected; meanwhile, the glycogen and glutamic acid levels were stable during the observation. Based on these results, the best recommendation is to serve the refrigerated scallops as sashimi for not more than two days and cook by the third day to preserve the quality.

Molecular Characterization and Expression of the LAP3 Gene and Its Association with Growth Traits in the Blood Clam Tegillarca granosa

Leucine aminopeptidase 3 (LAP3) is a metallopeptidase that cleaves N-terminal residues and is involved in protein maturation and degradation. In this study, we characterized the leucine aminopeptidase 3 (LAP3) gene from Tegillarca granosa (Tg-LAP3 for short), which appeared to consist of 15,731 nucleotides encoding 530 amino acids. We identified 12 introns and 13 exons in the Tg-LAP3 gene, suggesting a highly conserved genomic structure. The proximal promoter sequence consists of 1922 bps with a typical TATA box structure, which is the general structural characteristic of core promoters in eukaryotes. We found two functional domains in the Tg-LAP3 protein, including an N-terminal domain (41–174aa) and a peptidase_M17 catalytic domain (209–522aa). Multiple alignment showed that Tg-LAP3 shares 73.4% identity with LAP3 of Mizuhopecten yessoensis and 55.2–70.7% identity with LAP3 of other species. Quantitative analysis of Tg-LAP3 in embryos/larvae and adult tissues indicated that the highest expression occurred in eyebot larva, with limited expression in other stages; among tissues, the highest expression was found in the liver (p < 0.05). Association analysis found that three single-nucleotide polymorphisms (SNPs) (g.-488A > G, g.-1123C > T, and g.-1304C > A) in the proximal promoter were successfully typed, but there was no significant difference in growth traits (body weight, shell length, shell width, and shell height) among these genotypes. The results of our study demonstrate the functional roles of the Tg-LAP3 gene and provide valuable information for molecular marker-assisted selection (MAS) of the blood clam.

Dynamics of stock for yesso scallop Mizuhopecten yessoensis (Jay, 1856) in the northwestern Tatar Strait from the beginning of its fishery to nowadays

Settlements of yesso scallop Mizuhopecten yessoensis in the northwestern Tatar Strait (within the waters of Khabarovsk Region) are considered on the data of scuba (< 20 m depth) and dredge (> 20 m depth) surveys conducted in 2001–2018. To 2018, only two settlements remain in this area from 9–12 ones in 2010–2014; both remained settlements have no commercial value. Trend to decreasing of the settlements density is shown: the mean density was 3.0 ind./m2 in 2001, 0.20 ind./m2 in 2010, and 0.0005 ind./m2 in 2018. Commercially valuable scallops with the shell height > 120 mm prevailed in the settlements (86–100 %), whereas juveniles were rare or absent (1.6 %, on average) in all years of surveys. CPUE decreased from 200 kg/diver/hour in 2001–2003 to 10 kg/diver/hour in 2018. These changes are obviously reasoned by overexploitation of the population using dredging and scuba gathering. Total commercial stock of yesso scallop dropped to the minimal value in 2018: 200 t, that was in 4.5 times lower than the established limit. Thus, 5 years ban is established for M. yessoensis landing in the area.

Structure-dependent absorption of atypical sphingoid long-chain bases from digestive tract into lymph

Background Dietary sphingolipids have various biofunctions, including skin barrier improvement and anti-inflammatory and anti-carcinoma properties. Long-chain bases (LCBs), the essential backbones of sphingolipids, are expected to be important for these bioactivities, and they vary structurally between species. Given these findings, however, the absorption dynamics of each LCB remain unclear. Methods In this study, five structurally different LCBs were prepared from glucosylceramides (GlcCers) with LCB 18:2(4E,8Z);2OH and LCB 18:2(4E,8E);2OH moieties derived from konjac tuber (Amorphophallus konjac), from GlcCers with an LCB 18(9Me):2(4E,8E);2OH moiety derived from Tamogi mushroom (Pleurotus cornucopiae var. citrinopileatus), and from ceramide 2-aminoethyphosphonate with LCB 18:3(4E,8E,10E);2OH moiety and LCB 18(9Me):3(4E,8E,10E);2OH moiety derived from giant scallop (Mizuhopecten yessoensis), and their absorption percentages and metabolite levels were analyzed using a lymph-duct-cannulated rat model via liquid chromatography tandem mass spectrometry (LC/MS/MS) with a multistage fragmentation method. Results The five orally administered LCBs were absorbed and detected in chyle (lipid-containing lymph) as LCBs and several metabolites including ceramides, hexosylceramides, and sphingomyelins. The absorption percentages of LCBs were 0.10–1.17%, depending on their structure. The absorption percentage of LCB 18:2(4E,8Z);2OH was the highest (1.17%), whereas that of LCB 18:3(4E,8E,10E);2OH was the lowest (0.10%). The amount of sphingomyelin with an LCB 18:2(4E,8Z);2OH moiety in chyle was particularly higher than sphingomyelins with other LCB moieties. Conclusions Structural differences among LCBs, particularly geometric isomerism at the C8–C9 position, significantly affected the absorption percentages and ratio of metabolites. This is the first report to elucidate that the absorption and metabolism of sphingolipids are dependent on their LCB structure. These results could be used to develop functional foods that are more readily absorbed.