Abstract:In order to enhance the heat transfer intensity and uniformity in an air impinging freezer, an impinging freezing experimental table was designed as the research object, and a new nozzle structure—circular funnel nozzle was proposed. The numerical simulation technology was used to simulate the flow fields in the impinging freezing experimental table, which was testified by experiments. The flow medium was air, and the simulation process assumes： （1） The wall of static pressure chamber was adiabatic. （2） Air was an incompressible, homogeneous viscous fluid. （3） During the normal operation, the internal flow field of the model was regarded as steady state. The three-dimensional continuity equation, the momentum equation, the energy equation, the kinetic energy k equation and the turbulent dissipation ε equation were used. The cooling air inlet and outlet pressure were 250 Pa（P_in） and 0 Pa（P_out） respectively. For the frozen area, the cooling air inlet and outlet temperature was 230 K and 235 K. The mass flow rate at the cooling air inlet is 0.064 4 kg/s. The thermal conductivity of steel strip was 16.3 W/（m·℃）. Using the Plackett-Burman design, the significant factors for the average Nusselt number on the steel strip surface were obtained from the factors of outlet diameter D_E, funnel width L₃, funnel height L₁, jet height L₂, nozzle number N, nozzle spacing S and nozzle-to-surface distance H. These significant factors were funnel width L₃, jet height L₂ and nozzle number N. The others had little effect on the average Nusselt number. So in the next study, these factors adopted the median values. Then, using the Box-Behnken design, a mathematical model between those three significant factors and the two response values which were average Nusselt number Nu_ave and the heat transfer uniformity index η on the steel strip surface was established to determine the optimal structural parameters. The F value in the regression equation can be used to determine the influence of the factors on the response value. Therefore, the order of the factors affecting the average Nusselt number and the heat transfer uniformity index on the steel strip surface was nozzle number>funnel width>jet height. The interaction between the funnel width and the number of nozzle rows, the jet height and the number of nozzle rows were the most significant in the response surface analysis figures, which were consistent with the results of the variance analysis. The results showed that the optimal structural parameters were funnel width L₃=17 mm, jet height L₂=50 mm, nozzle number N=3. Substituting these parameters into the second-order polynomial equation, the average Nusselt number on the steel strip surface Nu_ave=448.68, heat transfer uniformity index η on the steel strip surface=0.232 9. The numerical simulation value was generally consistent with the predicted value, so it was reasonable to optimize the average Nusselt number and the heat transfer uniformity index on the steel strip surface by using the Box-Behnken design.

Abstract:Low-temperature storage of biological samples has become an essential aspect of various fields, including biomedical research, clinical diagnosis, and pharmaceutical development. It involves the preservation of biological samples in a controlled environment to maintain their integrity, quality and functionality. The success of these applications relies heavily on the use of appropriate refrigeration technologies that can provide the necessary temperature and humidity conditions for long-term storage. Therefore, this article analyzes the low-temperature characteristics of biological samples, and combines domestic and foreign literature to review the current application status of refrigeration technology in biological sample storage from four temperature zones： cold storage, freezing, low-temperature, and ultra-low temperature.The advantages and disadvantages of various refrigeration technologies are compared, and the optimal refrigeration technology in the same temperature zone is summarized. Finally, the bottleneck problems of equipment that restrict low-temperature storage of biological samples are discussed and the future development direction of refrigeration technology for low-temperature storage of biological samples is proposed. Aiming to provide a certain reference for the development of refrigeration technology in the biomedical field.

Abstract:To improve the utilization rate of Stichopus japonisus gonads and to prepare seafood flavor seasoning with better flavor.The enzymatic hydrolysateof gonads was subjected to a Maillard reaction with the addition of D-xylose and L-cysteine, and the changes of taste and odor of gonad enzymatic hydrolysates were analyzed by combining low molecular mass flavor intermediates, browning degree, free amino acids, flavoring nucleotides and volatile substances. The results showed that the content of umami and sweet free amino acids increased significantly and the proportion of bitter free amino acids decreased after the Maillard reaction； AMP was the main flavor-presenting nucleotide in enzymatic hydrolysates of Stichopus japonisus, and the content decreased significantly after the reaction； the types and amounts of key flavor compounds increased. The aldehydes were the main volatile flavor components, benzaldehyde was the most different substance before and after the reaction； pyrazine, thiophene and 2-ethylfuran were the characteristic flavor substances formed by the Maillard reaction.The gonadal enzymatic hydrolysate/D -xylose/L-cysteine Maillard reaction products have good flavor and can be used as a reference for the development of high quality flavoring bases and functional foods.

Abstract:Aflatoxin B₁ （AFB₁） is widely distributed and highly hepatotoxic, which can cause oxidative damage to human liver. In this study, a rat model of acute liver injury was established by injecting AFB₁ to explore the intervention effect and method of chitosan oligosaccharide （COS） with antioxidant activity on liver injury. The experiment was designed with blank group, COS control group, model group, COS intervention group, and positive control group. Consecutive gavage for 8 days, the model group, COS intervention and positive control group were injected with 1 mg/kg AFB₁ only on the 6th day. The intervention effect of COS on liver injury was evaluated by serum liver function indexes, lipid peroxide content, antioxidant enzyme activity and liver tissue sections in rats, and differentially expressed genes （DEGs） were obtained by RNA sequencing （RNA-Seq） technology to analyse the intervention mode of COS. The results showed that compared with the model group, the COS intervention group significantly decreased the serum liver function indexes and lipid peroxide content, and increased the activity of antioxidant enzymes； the observation of liver slices showed that COS was beneficial to improve the liver morphology of rats. RNA-Seq data showed a total of 968 DEGs in the COS intervention group compared with the model group, and the enriched gene ontology （GO） entries were mainly related to liver metabolic function, oxidative stress response and protein synthesis. In conclusion, COS has a certain intervention effect on AFB₁-induced acute liver injury, which provides a theoretical basis for COS to prevent AFB₁-induced liver injury.

Abstract:The extraction process of Japanese eel skin collagen was optimized using response surface methodology, and its physicochemical properties and allergenicity were investigated. Based on the single-factor experiment, the best extraction process was obtained based on the acid-enzymatic extraction method, with the material-liquid ratio, the concentration of extraction solution and the extraction time as the investigating factors and the collagen yield as the index. The results showed that the collagen contained five bands and belonged to type I collagen, and the percentages of essential amino acids and medicinal amino acids were 19.61% and 11.04%, respectively. The thermal transition temperature and thermal denaturation temperature of collagen were 38.5 and 28.3 ℃, respectively. The enzyme-linked immunosorbent reaction and simulated gastrointestinal fluid experiments showed that collagen has certain allergenic properties, providing a theoretical basis for further studies on eel skin collagen.

Abstract:Food-derived dietary dipeptidyl peptiase-Ⅳ （DPP-Ⅳ） inhibitory peptides and antioxidant peptides can contribute to scavenge free radicals in vivo and regulate blood sugar. In order to realize the high-value application of the defatted Antarctic krill powder and explore new ways to cure diabetes, DPP-Ⅳ inhibitory peptide and antioxidant peptide were prepared from defatted Antarctic krill powder by enzymolysis with alkaline protease, neutral protease and pancreatic enzyme. The relationships between time and hydrolysis degree, bioactivity and peptide yield rate respectively were investigated. Polypeptide was purified and analyzed, and the inhibitory sites were ascertained by molecular docking. The results illustrated that four peptides with both DPP-Ⅳ inhibitory activity and antioxidant activity were acquired by ultrafiltration, Sephadex G15 separation and purification and liquid-mass spectrometry, whose amino acid sequences were WPPLSPFRCPR, IPDWFLNRQ, FLWLKKTPLPL and DTVPWFPR, respectively. IPDWFLNRQ had the highest DPP-IV inhibitory activity among these four peptides, and its IC₅₀ value was （0.616±0.097） mmol/L. WPPLSPFRCPR possessed the higher antioxidant activity, whose DPPH EC₅₀ was （0.098 3±0.011） mmol/L and ABTS EC₅₀ was （0.116±0.073） mmol/L. Molecular docking results demonstrated that these four peptides mainly bind to the active center of DPP-Ⅳ and other sites through hydrogen, resulting in achieving inhibitory effect. This study prepared food-borne DPP-Ⅳ inhibitory and antioxidant peptides based on the defatted Antarctic krill powder, which provided references for the development and utilization of aquatic protein-derived hypoglycemic functional food and the research of novel hypoglycemic and antioxidant peptides.

Abstract:The collagen was extracted by acid, enzymolysis and hot water methods respectively from the body wall of Sipunculus nudus, and their physicochemical properties were analyzed. The three collagen extracts were compared respectively by amino acid composition, UV spectroscopy, Fourier infrared spectroscopy and SEM scanning electron microscopy. The effects of the three collagen zynolytes on the growth viability of HaCaT cells were investigated. The results show that the extraction rate of collagen by hot water method is higher than the other two methods, and all three collagens contain the collagen characteristic amino acids Gly, Pro and Hyp. The UV and IR spectrograms show that all three collagens have obvious absorption peaks near 222 nm, and there are absorption peaks of amide A and amide B and characteristic peaks of amide Ⅰ, Ⅱ and Ⅲ, suggesting that all three collagens belong to type I collagen with a three-stranded helical structure. And the results of scanning electron microscopy show that the three-stranded helical structure of collagen extracted by acid method is more complete and maintains the original structure of collagen fibers better than that of enzymatic method and hot water method. The collagen peptides extracts have the ability to significantly increase the viability of normal and UVB-damaged HaCaT cells in the range of 50?100 μg/mL, indicating that the enzymatic products of collagen of Sipunculus nudus have good potential applications in skin photoaging repair.

Abstract:In this study, the microsatellite search software MISA was used to search for the perfect microsatellite in the whole genome of three Culterinae species, and its distribution pattern was analyzed. As a result, in the genome of （Culter alburnus,1.055 Gb）, （Anabarilius grahami,1.006 Gb）, and （Megalobrama amblycephala,1.116 Gb）, 772 276, 548 726, and 772 329 perfect microsatellites were screened out, respectively. The relative frequency were 732.0/Mb, 553.2/Mb, and 691.2/Mb, respectively. The total lengths of the microsatellites were 14.29 Mb, 9.42 Mb, and 15.02 Mb, respectively, accounting for 1.35%, 0.94%, and 1.35% of the total length of the genome sequence. Among the complete microsatellites with 1-6 different base repeat types, the orders of 6 base types from the three species of Culterinae were the same. Each had the largest number of mononucleotide repeats, followed by dinucleotide repeats, tetranucleotide repeats, trinucleotide repeats, pentanucleotide repeats, and hexanucleotide repeats. The highest frequency core repeat categories of trinucleotide and tetranucleotide in the three species of fish is AAT and AGAT, respectively. However, the number of AT is more than AC repeat in the dinucleotide of Culter alburnus. The distribution frequency of microsatellites of different base types in the three fish species decreased with the increase of the copy number and length of the repeat units. The length of the microsatellites repeat unit was mainly 10-30 bp, accounting for 90.54%, 94.27%, and 89.17% of the microsatellites, respectively. The results of this study may provide a reference for the further study of Culterinae genome characteristics and contribute basic data for future investigations into molecular marker-assisted breeding and genetic information assessment of 3 Culterinae species.

Abstract:In this paper, the changes of superoxide dismutase （SOD） activity and malondialdehyde （MDA） content in hepatopancreas of Pomacea canaliculate in Guangzhou, Shanghai and Chengdu under different temperature, salinity and dissolved oxygen environmental stresses were studied to clarify the mechanism of environmental stress on the physiology of Pomacea canaliculate. The experimental results showed that under the stress of temperature, dissolved oxygen and salinity, the SOD activity and MDA content of the hepatopancreas of the snails increased first and then decreased, and reached the maximum value at 24 h~48 h, and returned to the initial level at 72 h. Under the combined temperature-salinity stress, the SOD activity and MDA content in the hepatopancreas of the snails were higher than those under the single factor stress, and the temperature and salinity showed a synergistic effect. Under single or complex stress, SOD activity and MDA content in liver and pancreas of the snails varied from region to region.

Abstract:This experiment was used to study the effects of dietary Clostridium butyricum addition on growth performance, serum biochemical indices, immune function and disease resistance of grass carp （Ctenopharyngodon idellus）, in order to provide theoretical reference for application of C. butyricum in aquaculture. A total of 600 healthy grass carp with similar body mass of （23.78±0.68） g were randomly divided into 4 groups with 3 repeats for each group and 50 fish per repeat. Grass carp in the control group （T0 group） were fed a basal diet, while others in experimental groups （T1, T2, T3 groups） were fed basal diets added 1×10⁷, 1×10⁸, 1×10⁹ cfu/g C.butyricum, respectively. The experimental period lasted for 56 d. The results showed as follows： Dietary adding C. butyricum had significant effects on the weight gain rate （WGR） and specific growth rate （SGR） of grass carp, while had no important effect on survival rate （SR）. Conversely with the control group, the activities of superoxide dismutase （SOD） and lysozyme（LZM）, as well as the content of complement C3 were significantly higher in the experimental groups, while the activity of aspartate aminotransferase （AST） was significantly decreased. The expression of 4 immune-related genes （IL-8, IL-1β, IgM and TNF-α genes） in the experimental groups were significantly higher than that in the control group. After feeding probiotics for 56 days, the grass carp were challenged with Aeromonas hydrophila. The results indicated that the cumulative mortality rate of grass carp in the experimental groups were lower than the control group. Based on the results of this experiment, feeding basal diets added C. butyricum has a good impact on growth, immunity and disease resistance improvement for grass carp．

Abstract:Channa striata is a high-value, carnivorous freshwater fish species widely farmed in the Southeast Asia. However, its basic nutrient requirements during the grow-out stage （body mass> 100 g） are largely unexplored. In this study, we first explored the optimal protein requirement of Channa striata. Six isolipidic （15%） diets with varying protein levels were formulated by adjusting the fish meal inclusion level. Fish with a mean initial body weight of 150 g were fed these experimental diets to apparent satiation twice daily for 8 weeks. Our results showed that the growth performance and feed efficiency of Channa striata improved and plateaued while the protein retention increased and then declined, as the dietary protein level increased from 36% to 51%. Using the weight gain and protein retention as response variables, the protein requirement of Channa striata was estimated to be 41.5% and 42.3%, respectively, by the regression analysis. We further explored the optimal lipid requirement of Channa striata based on the protein requirement result. Six isoproteic （42%） diets with varying lipid levels were formulated by adjusting the soy lecithin inclusion level. Fish with a mean initial body weight of 150 g were fed these experimental diets to apparent satiation twice daily for 8 weeks. The results showed that the growth performance and feed efficiency of Channa striata improved and plateaued as the dietary lipid level increased from 9% to 19%. In contrast, the lipid retention increased as the lipid level increased from 9% to 15%, but declined as dietary lipid further increased. Using the weight gain and protein retention as response variables, the lipid requirement of Channa striata was estimated to be 15.2% and 15.3%, respectively, by the regression analysis. In conclusion, the optimal protein and lipid requirement of Channa striata during the grow-out stage was estimated to be 41.5%-42.3% and 15.2%-15.3%, respectively.

Abstract:To reveal the drug-resistance potential of Aeromonas hydrophila, the micro broth dilution method and comparative genomics method were used to analyze its drug-resistance potential in this study. The results showed that enrofloxacin, neomycin sulfate, florfenicol and doxycycline hydrochloride had inhibitory effects on the three strains, while sulfamethoxam had no inhibitory effect on the three strains. The resistance phenotype of the strains was not corresponding to the resistance genes one by one, and some strains could show related resistance phenotype even though the resistance genes were not annotated； The genomes of the three newly sequenced strains differed in size, and their genetic relationships were not close, but the number of drug-resistant genes was basically the same. After calculation of ANI （Average nucleotide identity）, comparative analysis of genomes revealed that the genomes of A. hydrophila showed strong variability, and there were still large differences among genomes of even close strains. Phylogenetic analysis showed that the strains from different hosts were scattered in the evolutionary tree, and the related strains were distributed in different countries and regions. A total of 21 drug resistance genes were annotated in all strains in CARD （The Comprehensive Antibiotic Resistance Database ）, of which 7 were shared by all strains. The reason for this phenomenon is likely to be due to the strong variability of A. hydrophila genome and the wide distribution of its hosts. Frequent gene exchange between strains promotes the rapid spread of drug-resistance genes throughout the species, so even if the genome changes between strains are large, the changes of drug-resistance genes between strains are small.

Abstract:In order to explore the temporal and spatial variation characteristics of phytoplankton functional groups in Qingcaosha Reservoir, Shanghai, and their relationship with environmental factors, as well as the similarities and differences between the characteristics of phytoplankton communities at the inlet and outlet and the reservoir, monthly phytoplankton surveys were conducted in 2021, and the data were analyzed using the phytoplankton functional group （FG） method and redundancy analysis （RDA）. The results showed 143 species of phytoplankton were identified in Shanghai Qingcaosha Reservoir during the investigation. The average biomass of phytoplankton was （0.64±0.35） mg/L. There were 25 functional groups of phytoplankton in the reservoir, among which K, Lo, H1, S1, B, D, P, MP, F and G were dominant functional groups. There were 3 phyla and 40 species in the inlet water, 5 phyla and 48 species in the outlet water. These species belonged to 15 groups and 19 functional groups. There were five groups and nine groups of dominant function groups in the inlet and outlet water, respectively. The average annual biological density and biomass of the inlet water were 118.17×10⁴cell/L and 0.16 mg/L, respectively. Compared with the inlet water, the average annual biological density and biomass of the outlet water increased by 34.85% and 50.12%, respectively, and there was a significant difference between the inlet water and outlet water biomass.The ANOVA analysis showed that there was no significant difference in the composition of phytoplankton functional groups at the head, middle and tail of the reservoir,and the species similarity of the three reservoirs was moderate.Redundancy analysis （RDA） showed that water temperature（WT）, ammonia nitrogen（ NH₄^＋-N） and dissolved oxygen （DO） were the main environmental factors affecting the dominant functional groups of phytoplankton in Qingcaosha Reservoir.In this study, the division and succession of phytoplankton functional groups in Qingcaosha Reservoir were analyzed, and the differences of phytoplankton functional groups in the inlet water and outlet water were compared, which provided a theoretical basis for the protection of water resources in the reservoir.

Abstract:A large-scale emergency rescue operation for Yangtze finless porpoise was carried out in November 2022 and February 2023 in the southern sand pit waters of Songmen Mountain in Poyang Lake.This paper describes the population structure and growth status of Yangtze finless porpoise for the first time, using the physical examination data obtained during the rescue period and the results of the subsequent acoustic survey of Yangtze finless porpoise in this area. The average body length of this population is （135.01±16.95） cm, the average body mass is （42.37±14.71） kg, the average maximum body circumference is （88.32±9.32） cm, the average body mass index is （22.83±4.72） kg/m², and the average body circumference index is 65.88%±5.86%. The average thickness of axillary fat layer is （2.51±0.55） cm, the average thickness of anal fat layer is（2.47±0.31） cm, and the average thickness of maximum body fat layer is （2.08±0.34） cm； the population structure was relatively large for young individuals and more males, and the population showed an extended type； the population density of Yangtze finless porpoise in the waters was greater than 2 heads/km², and the population size was about 39 to 111 individuals. On the whole, the Yangtze finless porpoise population is in good health and has good breeding potential, and the attention and protection of the Yangtze finless porpoise population should be strengthened.

Abstract:Cephalopod holds significant importance in marine ecosystems as it occupies a wide range of trophic level in the marine food web and has a high production to biomass ratio. As a source of high-quality animal protein, cephalopod has become one of the world's most exploitable fishery resources, landings of which have increased rapidly in recent decades. In contrast to traditional fish stocks, cephalopod has a variety of special biological characteristics, including short life cycle, rapid growth rate, and complex population structure. Furthermore, the biomass of cephalopod is highly susceptible to fluctuations in the marine environment, making the study of cephalopod population dynamics and stock assessment more difficult and challenging than for traditional fish stocks. That is because most assessment models assume the existence of multiple year classes and population dynamics associated with iteroparity. This paper provided an overview of the life history characteristics of cephalopod and the relationship between its resources and marine environmental factors； teased out the suitability of stock assessment models applied to cephalopod, such as the surplus production model, delay-difference model, depletion model, age structure model, etc.； and pointed out the problems and limitations of the current research on cephalopod stock assessment. Therefore, based on the comprehensive analysis conducted, it can be concluded that the research is still in its preliminary stage. The improved depletion model and surplus production model are the most commonly used, but neither is able to develop time-sensitive fisheries management measures. We finally proposed the development direction for optimizing the research on cephalopod stock assessment from the following three aspects： improving the accuracy and reliability of input parameters, conducting long-term systematic investigations of environment and resources, and developing new assessment models.

Abstract:In this paper, biological measurements such as body length and body weight and identification of stomach contents were carried out based on Pacific cod（Gadus macrocephalus）samples captured in the Yellow Sea from 2017 to 2021. Decision tree method was used to analyze 489 stomach contents data to explore the changes of feeding habits with body length and seasons. The results showed that the relative importance index of Crangon affinis and Engraulis japonicus was relatively high in 2017—2021, and the next were Enedrias fangi, Alpheus japonicus and Gobiidae. Its feeding habits vary greatly with seasons, mainly preying on Crangon affinis and Engraulis japonicus in summer and autumn, while its feeding habits are relatively wide and its Shannon-Wiener index is higher in spring and winter, which may be related to the overwintering of most fishery species in the Yellow Sea during spring and winter. In addition, the Pacific cod 's feeding habits change with the growth of its body length. The juveniles mainly feed on crustaceans, while the adults shift to eat Gobiidae, Enedrias fangi, etc. The main reason is that the Pacific cod 's mouth slit becomes larger, its swimming ability becomes stronger, and it has more nutrients to meet the growth requirements. Other Pacific cod individuals were found in the gastric contents, indicating cannibalism. In addition,compared with previous studies, the diet abundance of prey gradually decreased, Euphausia pacifica and Larimichthys polyactis almost did not appear in the stomach, and the importance of Engraulis japonicus gradually decreased, and Gobiidae are becoming more important.

Abstract:In recent years, the people's life happiness index has become the key word in the government work report. Paying attention to the "life happiness index" is not only the embodiment of the "people-oriented" scientific development concept, but also the internal requirement of the harmonious development of economy and society.By means of questionnaire interview, 150 affected fishermen from Jingjiang District of Taizhou, Jiangsu Province, Jiangyin County of Wuxi, Wujin District of Changzhou, Yixing District of Wuxi, Wuzhong District of Suzhou and Wujiang District of Suzhou were selected as the research objects to analyze the current situation of life happiness of local affected fishermen and its influencing factors. The Generalized additive model （GAM） and life happiness index scale were built to analyze the factors affecting the happiness of life of affected fishermen.The study found that healthy physical condition, stable living pattern, increasing household expenditure, good living environment and higher education level were the main factors that made fishermen satisfied with their lives. Unhealthy physical condition, unstable life pattern, lack of long-term money planning awareness and reasonable control of consumption expenditure after having a certain amount of savings, and the number of two or more children living independently are the main factors that lead to fishermen's dissatisfaction with life. The government can improve the life happiness index of affected fishermen by relaxing housing conditions, creating new jobs, carrying out spiritual civilization construction, training on the prevention of common diseases, building new public activity facilities and other measures.

Abstract:The South Pacific Regional Fisheries Management Organization （SPRFMO） plays a vital role in managing fishery resources and protecting marine ecosystems in the South Pacific Ocean. Compared with other regional fisheries management organizations （RFMOs）, SPRFMO is unique for its management philosophy and management measures. As a member of SPRFMO, China has complied with the established measures in the exploitation and conservation of fishery resources and has steadily continued to enhauce its compliance awareness and compliance ability. However, there is still room for China to further improve its active participation in rule-making.This paper discusses how China, with substantial SPRFMO compliance experiences and in good knowledge of SPRFMO management philosophy and management measures,takes advantage of its strengths in squid production and research to improve its involvement in making rules of procedures and the conservation and management measures, thus to facilitate the conservation and management of resources and sustainable development of fisheries in the South Pacific Ocean with Chinese solution to fisheries governance while safeguarding the rights and interests of China′s fisheries.