On the intraspecific competition of yellowfin sole Limanda aspera (Pallas, [1814]) (Pleuronectidae) in the eastern part of the Sea of Okhotsk

Based on the longterm observations for 1963–2019, the article provides an assessment of the yellowfin sole generation mortality dynamics depending initial abundance and population dynamics in view of abundance and biomass. Individual growth and matiration rates were evaluated in generations with different initial abundance and in different states of population dynamics. Results indicated about intraspecific competition in yellowfin sole in the eastern part of the Sea of Okhotsk, expressed in specifics of the dynamics of stock abundance, growth and maturation. Forming generation stock abundance in early and later ages has different character. The more exceeding number of parental eggs spawned, the more generation abundance of yearlings getting exactly compensated by mortality (complete compensation). Older generations demonstrate the phenomen of “overcompensation”, when mortality of generations appeared in the years of higher egg production exceeds fertility. In the period of population growth and stabilization at a high level the period of the Yellowfin sole abundance fluctuation cycle gets shorter and the amplitude – smaller. Effects of intraspecific competition on the growth of individuals are revealed. Negative effects of the competition authentically revealed in elder age groups were not observed in younger age groups. An increase of the Yellowfin sole abundance brings negative effects on maturation rate of males with almost no such effects on females. To the greatest extent such effects can be seen in young age groups, at the beginning and middle stage of maturation.

Optimization of Texture-Modified Yellowfin Sole (Pleuronectes aspera) by Enzymatic Treatment and Superheated Steam Treating to Improve Quality Characteristics

This study aimed to optimize the texture modification process of yellowfin sole (Pleuronectes aspera) to improve its quality characteristics for easier consumption by the elderly. Yellowfin sole was immersed in enzyme solution (Protamex:Neutrase = 1:2), marinated in herbal extract solution, and roasted by superheated steam. The product was evaluated for microbial, physicochemical, and sensory properties, as well as shelf life. Specifically, the optimal enzymatic treatment comprised a protease concentration of 1.00% (w/v) with an immersion time of 3.16 h. The optimal marination herb was determined to be bay leaves, as indicated by highest overall acceptance. The texture modification process led to lower hardness and higher overall acceptance values (76.23 kN/m2 and 8.38, respectively) compared with nonenzyme processed product (120.43 kN/m2, 7.43), also retaining high nutritional value and low trimethylamine levels. Shelf-life analysis indicated microbial activity was inhibited (not detected), low levels of total volatile basic nitrogen (10.50 mg%), low levels of thiobarbituric acid reactive substances (0.12 mg MDA/kg), and stable pH values (6.5–7.0). Overall, the texture-modified yellowfin sole possessed a soft flesh texture suitable for consumption by the elderly, with acceptable microbial, physicochemical, and sensory qualities.

Pemodelan Molekuler Peptida Bioaktif Laut sebagai Antikoagulan Alami terhadap Enzim Sitokrom P450 (CYP) 2C9

Anticoagulants are very important for the treatment and prevention of thrombotic disorders. The use of conventional anticoagulants like heparin and warfarin can cause bleeding complications. To find safer anticoagulant therapy agents, the development of isolation of new anticoagulant compounds has shifted towards natural sources. Bioactive peptides can be considered a better alternative because of their therapeutic potential in the treatment of various diseases. Several peptide molecules have been shown to inhibit the cytochrome P450 (CYP) 2C9 enzyme as a natural anticoagulant, such as bioactive peptides produced by yellowfin sole (Limanda aspera) and bioactive peptides in blue mussel (Mytilus edulis). This study aims to identify and evaluate the interactions that occur between peptide molecules with the cytochrome P450 (CYP) 2C9 enzyme using protein-peptide docking methods. Bioactive peptide sequencing was modeled using the PEP-FOLD software. The best conformation was chosen for an interaction study against the macromolecule of cytochrome P450 (CYP) 2C9 enzyme using PatchDock software. Further observations were made of interactions formed using BIOVIA Discovery Studio 2020 software. Based on the results of protein-peptide docking, the yellowfin sole peptide molecule has a good affinity against the macromolecule of cytochrome P450 (CYP) 2C9 enzyme, with an ACE score of −2527.01 kJ / mol. Therefore, the bioactive peptide is predicted to be used as a candidate for the cytochrome P450 (CYP) 2C9 enzyme inhibitor.

Contrasting the variability in spatial distribution of two juvenile flatfishes in relation to thermal stanzas in the eastern Bering Sea

Groundfish species in the Bering Sea are undergoing pronounced changes in spatial distribution and abundance due to warming ocean temperatures. The main drivers of interannual variability in this ecosystem are the alternating warm and cold thermal stanzas. Yellowfin sole (Limanda aspera; YFS) and northern rock sole (Lepidopsetta polyxystra; NRS) are commercially-valuable flatfishes in the Bering Sea and are among the most dominant groundfish species there in numbers and biomass. We examined the variability in the spatial distribution and abundance of juvenile NRS and YFS in relation to the ice and temperature conditions associated with warm-cold thermal shifts from 1982 to 2017. The goal was to assess the implications of the fluctuating thermal environment for Bering Sea flatfish production. We found ice cover and bottom temperature indices in the preceding 1 to 3 years to be the best predictors of NRS juvenile distribution. In contrast, these indices were not significantly correlated with YFS juvenile distribution, which could be an artifact of their relatively low availability to sampling. A warm stanza, as the Bering Sea is currently in, is expected to favor high numbers of NRS juveniles and the northward expansion of their distribution.