Abstract:In order to further understand the role of WNT4 in the sex determination process of Hyriopsis cumingii, the full-length cDNA of WNT4 gene was cloned by RACE method(Rapid-amplification of cDNA ends), which was 1 560 bp, including 5'-UTR 396 bp and 3'-UTR 24 bp. The open reading frame (ORF) was 1 140 bp, encoded a putative protein of 379 amino acids that contained a WNT family specific domain. Homology analysis of the amino acid sequence of WNT4 showed that the evolutionary relationship and structural function of the gene were conserved among species. Real-time quantitative PCR (qRT-PCR) analysis of WNT4 gene in the male and female tissues (the mantle, the adductor muscle, the gill, the gonad, the foot and the liver), indicated that it participated in diverse biological processes. It was highly expressed in gill, foot, and liver. There was significant difference between male and female in gonads, adductor muscle, and foot, and the expression of female gonads and adductor muscle was significantly higher than that of males. In situ hybridization results showed that there was obvious hybridization signal in the female oocyte cell. It was speculated that WNT4 gene was related to sex determination.

Abstract:In order to detect the effect of editing different functional regions of genes on fish coloration, fertilized eggs of AB strain of homozygous zebrafish (Danio rerio) were microinjected by CRISPR/Cas9 technology, Tyr gene were disrupted in the exon 2 and non-poly (A) addition signal of 3'-UTR, and mutants with disruption of different functional regions were obtained. The results showed that:the relative expression level of Tyr gene was detected in the examined stages of fertilized egg to 15 dph larvae in wild-type zebrafish, and the relative expression level increased to the highest level at melanin formation of eyes; the melanocytes were not observed in mutant embryo and larvae with disrupting the CDSregion of Tyr gene, displaying complete albino, then, the melanocytes were observed in adult fishes with broken melanocyte stripes. The mutants with disrupting non-poly (A) addition signal of 3'-UTR region of Tyr gene showed the same melanocyte stripes with wild-type zebrafish, indicating normal melanin synthesis in them. It was indicated that significantly phenotypic change would occur by disrupting CDS region of gene, while no obvious phenotypic change was detected by disrupting non-poly (A) addition signal of 3'-UTR region of gene.

Abstract:In order to explore the difference in growth performance and culture effect of Chinese mitten crab inbred families and hybrid families derived from Liaohe River and Yangtze River during adult Eriocheir sinensis culture stage, the juveniles were reared to adult crabs under similar pond conditions. The growth, puberty molting rate and gonadal development were comprehensively compared, and the differences in survival rate, yield, feed coefficient ratio and final body mass distribution were further evaluated.The results illustrated that there was no significant difference in the mean body mass, weight gain rate (WGR) and specific growth rate (SGR) of Eriocheir sinensis during the growth stage (P>0.05).The peak of female puberty molting appeared from July 25 to August 25, and the peak of male puberty molting did from August 25 to September 25. Compared with Eriocheir sinensis from Yangtze River basin, no significant earlier puberty molting was observed from Liaohe River. From September to November,the hepatosomatic index (HSI) of Eriocheir sinensis individuals gradually decreased, and the gonadosomatic index (GSI) showed a significant upward trend. Significant differences were observed in survival rate, yield, feed coefficient ratio among these four inbred and hybrid families (P<0.05).The final body masses of the adult females were concentrated from 100.00 g to 175.00 g,and the males were concentrated from 175.00 g to 225.00 g. In summary,there was no significant difference in growth performance between inbred families and hybrid families derived from Liaohe and Yangtze River basins (P>0.05).After adaptive culture of Eriocheir sinensis from Liaohe River basin, the growth performance was improved, and the two-year early-maturing trait disappeared.The hybrid families with Yangtze River basin of Eriocheir sinensis as the female parent had higher survival rate and yield.

Abstract:A 56-days feeding trial was conducted with tiger puffer Takifugu rubripes (average initial body of 14 g), in order to investigate the effects of dietary bile acid supplementation on the fatty acid composition and anti-oxidative capacity. The feeding trial was conducted in indoor flow-through seawater system. Two diets with suitable (8.5%, diet C) or high lipid level (12.5%, diet HL) were prepared. BA as porcine bile extract mainly composed of hyodeoxycholic acid was supplemented into the two diets at the level of 0.02% to formulate diet BA and diet HLBA, respectively. A fifth diet was prepared by supplementing an excess level of porcine bile extract (0.10%) into diet C (diet HBA). Each diet was randomly fed to triplicate tanks. The results showed that the MUFA contents in liver and muscle were reduced by dietary bile acid supplementation, significantly lower in group HBA than in the control group (P<0.05). The n-6 PUFA contents in groups HLBA and HL were significantly lower compared to other groups. In the groups with moderate lipid level, the contents of C20:0, C16:1n-7, C18:1n-9, C18:2n-6, C20:4n-6, C18:3n-3, C18:4n-3, C20:5n-3 and C22:6n-3 in the liver tended to decrease with increasing bile acid levels. The serum activities of glutathione peroxidase and superoxide dismutase tended to increase with increasing bile acid levels, and were significantly higher in high-lipid groups than in the control group (P<0.05). However, the glutathione reductase activity showed an opposite pattern. The relative mRNA expression in liver of the control group was significantly higher than that in other groups, while the gene expression of peroxiredoxin 1 in group BA was significantly higher than that in the control. The bile acid supplementation in high-lipid diets significantly increased the hepatic gene expression of catalase. In conclusion, the dietary bile acid supplementation reduced the contents of a series of long-chain fatty acids in both diet and fish tissues,and the effects of dietary bile acid on serum activity of anti-oxidative proteins were different from those on the hepatic expression of anti-oxidative genes.

Abstract:We exploited strand displacement amplification (ISDA) and exponential amplification (EXPAR) to design a label-free, ultrasensitive fluorescence sensing system for the detection of Pb²⁺. In the presence of Pb²⁺, the substrate strand is rapidly cleft by the activated GR-5 DNAzyme to release Primer 1. Primer 1 hybridizes to template 1 and is extended by DNA polymerase (BSM) to form a double-stranded nucleotide with a recognition sequence for restriction endonuclease (Nt. BbvCI). The nicks generated by BSM cleavage from Nt.BbvCI re-extended to form double-stranded nucleotides and release the signal G4-DNA fragment. The G4-DNA fragment can also be used as a primer for template 2 to initiate a series of amplification process, thereby releasing more signal G4-DNA fragments. G4-DNA binds to protoporphyrin zinc (ZnPPIX) to produce a strong fluorescent signal. The effects of various factors on the sensing system were investigated. Under the optimal experimental conditions, the linear detection range of Pb²⁺ was 0.1-50 nmol/L, and the LOD was 0.03 nmol/L (S/N=3). The regression equation is y=288.7x+744.7 (y is the fluorescence intensity and x is the Pb²⁺ concentration). Interference experiments show that the sensing system has good selectivity for Pb²⁺ against other metal ions. This method was applied to the detection of Pb²⁺ in environmental water, and the recoveries were obtained from 94.0% to 103.0%. The proposed sensing system has the advantages of simple operation, good selectivity, high sensitivity and strong anti-interference performance, and can be used for high-sensitivity detection of Pb²⁺ in environmental water samples.

Abstract:The fish community in Jize Reservoir were seasonally investigated from September 2017 to October 2019. The main fish resources were detected by dual-frequency identification sonar (DIDSON), and the fishery acoustic data were processed by Software Echoview. A total of 30 fish species from 7 families 5 orders were collected, with 28 species of freshwater fish, 1 species of estuary fish, 1 species of emigratory fish. And the herbivorous fishes, phytophagous fishes, planktivore fishes, omnivorous fishes, primary carnivorous fishes and second carnivorous fishes were 2,3,2,9,5 and 9 species respectively. The planktivore feeding fishes including silver carp and Bighead Carp ranked No.1 in both individual number and mass in catches. The dominant fishes (IRI>1 000)were Hypophthalmichthys molitrix, Hypophthalmichthys nobilis, Hypophthalmichthys nobilis, Coilia nasus. The total number of fish was 133 300 and the total resource were 115 800 kg respectively in Jinze Reservoir by the DIDSON, the fish stocksperm 2 was at a high level according to water conservancy industry standard of the people's Republic of China SL 563-2011, ICS 93,160, P55. The present fish community structure was significant difference comparing with that before the reservoir was running, but which was high similarity with the fish fauna in Lake Taihu.

Abstract:To clarify the effect of tide on the fish larvae and juvenile community, fish larvae and juveniles were collected monthly at 2 stations (St.1:31°35.500'N,121°20.004'E; St.2:31°33.500'N,121°20.000'E) on the spring tide between May 2017 and April 2018. Sampling was conducted in North-South longitudinal section of the south branch of Yangtze River estuary, using a larval net (1.3m mouth-diameter, 0.5mm mesh). Moreover, according to the tidal changes (4 flood tides, 4 ebb tides), each haul was made parallel to the surface layer and middle layer. A total of 51 783 fish larvae and juveniles were collected, representing 32 species from 11 families. The five dominant species was Hemiculter bleekeri(87.05% of the total),Carassius auratus(3.45% in total of the fish), Culteral burnus(3.16% in total of the fish), Rhinogobius giurinus(2.16% in total of the fish), Repomucenus olidus(0.01% in total of the fish). The pre-flexion stage was the dominant stage (95.21% in total of the fish), followed by flexion stage (4.54% in total of the fish), post-flexion stage (0.12% in total of the fish), juvenile stage(0.12% in total of the fish) and yolk-sac larval stage(0.01% in total of the fish). The results of average density analysis showed that the monthly average density and catches were affected by the flood tide and ebb tide to a certain extent:average density of flood tide is larger than that of the ebb tide. The five dominant species were affected by the changes of tide besides the Rhinogobius giurinus, the body length distribution of other four species both showed higher at nighttime than daytime, and the annual distribution of five dominant species showed obvious monthly changes. The developmental stage analysis showed that:except for the pre-flexion stage, the flexion stage of the five dominant species at flood tide were higher than those at the ebb tide, while the post-flexion stage in ebb tide were lower than those at flood tide. The results of ecological types analysis showed that the total fish collection of freshwater, brackish water and offshore at flood tide were greater than that those at ebb tide. The correlation analysis showed that there was a significant correlation between dissolved oxygen concentration, temperature and average density, but no significant correlation between salinity and average density.

Abstract:From data collected at 112 sites in waters near Mauritania from September 20th to December 31st, 2017, the relationship model based on Quantile Regression method was established using 78% randomly selected sites between catch per unit effort(CPUE) of chub mackerel (Scomber japonicus) and environmental factors such as chlorophyll-a concentration, sea surface temperature and sea surface salinity, and the predicted CPUE model was validated by the remaining 22% site data, then General Additive Model (GAM) was used to evaluate the impact of environmental factors to CPUE. The integrated habitat index (IHI) of chub mackerel in the waters near Mauritania was calculated. The predicted CPUE values of the modeled and validated sites were tested by Wilcoxon test. The predicted CPUE values were tested by Spearman correlation and double tail tests. The relationship between IHI and CPUE was analyzed. The results showed that:the most significant environmental factor affecting CPUE of chub mackerel was sea surface temperature, followed by the interaction between temperature and salinity and sea surface salinity, while chlorophyll-a concentration had no significant effect on CPUE; there were no significant differences between the predicted CPUE and the nominal CPUE of the modeled sites or the verified sites; the IHI model had good predictive ability on CPUE of chub mackerel; the higher IHI were defined in the areas of 17°25'W-17°45'W and 20° 15'N-20 °45'N. It was suggested that the Chinese fishing vessels should concentrate their fishing efforts in this area on the second half of the year in order to increase their catch.

Abstract:According to the fisheries data of Dosidicus gigas off Peru in the spring (August to October), summer (November to January), autumn (February to April) and winter (May to July) from 2006 to 2014, combined with three key marine environmental factors:sea surface temperature (SST), sea surface height (SSH), and net primary production (NPP), habitat suitability index models (HSI) with different weighting scenarios were employed to predict the fishing ground distribution of Dosidicus gigas off Peru. The relationship between catch per unite effort (CPUE) and SST as well as SSH and NPP was used to establish a suitability index (SI) model for each factor, and the arithmetic weighting method was applied to develop an integrated HSI model. Based on the proportions of catch and effort at each HSI class interval from the different weighted HSI models, the optimal models for different seasons were selected. The HSI model was validated by the data from 2015. The results showed that, the CPUE and the latitude gravity center of fishing ground (LATG) showed significant interannual and seasonal changes. In terms of interannual changes, CPUE basically fluctuated between 2 and 7 t/d, and the LATG basically ranged from 10°S to 18°S. On the seasonal change, CPUE in winter and spring was high, and the LATG was located in the northward regions on the fishing ground. In summer, the CPUE increased with the southward shift of the LATG. Compared with spring, the habitat moved 1.5° southwards and the CPUE increased by 6.7%. The change trend in autumn was the same as in winter and spring. The weighting schemes of the optimal habitat model in different seasons were different. The optimal weighting scheme of the spring was Case 9; the environmental factor with the highest weight was SST; the optimal weighting scheme of the summer was Case 7, and SST, SSH, and NPP weights were equivalent; the optimal weighting scheme for the autumn was Case 3, and the highest weighting was SSH. The above results indicated that the environmental factors had different impacts on the habitats of the Dosidicus gigas off Peru in each season. The accuracy of habitat predictions for each season was 84.68%, 78.56%, 72.74%, and 68.70%. It was helpful to understand the impacts of environmental factors on Dosidicus gigas stocks off Peru at different seasons, providing a scientific basis for the distant-water operations of Chinese squid-jigging fisheries.

Abstract:Based on the data collected by Inter-American Tropical Tuna Commission (IATTC) from 2015 to 2017 and the matched satellite remote sensing data, a two-stage boosted regression tree(BRT) model was built to model the habitat of bigeye tuna free-swimming schools in the eastern Pacific Ocean and explore its temporal and spatial distribution pattern. The results showed that, compared to environmental factors, spatial factors had a greater impact on the abundance of bigeye tuna free-swimming schools. In terms of environmental factors, latitude, longitude, mixed layer depth, month, and sea surface temperature are the main influential factors that affect the fishing success rate of bigeye tuna free-swimming schools, while the main factors affecting the abundance of bigeye tuna free-swimming schools are longitude and sea surface chlorophyll-a concentration. Bigeye tuna is mainly located in the sea area south of 10°S and west of 95°W. From July to September in 2016 and Febuary to April in 2017, the spatial distribution predicted by the two-stage BRT model showed that some highly dense tuna free-swimming schools inhabited the equatorial waters with longitude of 150°W and latitude of 0° and waters with longitude of 120°W and latitude of 10°S, respectively. With respect to temporal trend, the inter-annual variation of the monthly average of the abundance of bigeye tuna is small, but the monthly difference is large. The monthly variation revealed that the highest value occurred in July and then dropped to the lowest value in August. The results of this study can provide reference for conservation and management of tuna resources in the EPO.

Abstract:The fishing data of O.bartramii from 150°E -165°E, 39°N-45°N in the northwestern Pacific Ocean from August to October from 2004 to 2015 were used. The interannual and seasonal variations of gravity centers of the fishing ground and its relationship with marine environment were studied. The influences of abnormal climatic events on sea surface temperature (SST) and the fishing ground's gravity centers were evatuated. It was found that the appropriate SST range of fishing ground for O. bartramii is 13-22℃, which decreased month by month. The interannual and seasonal variations of gravity centers of the fishing ground were significant, and the seasonal variation is consistent with the migration route for O. bartramii. The clustering results of the center of gravity of fishing grounds in each month are divided into three categories, which corresponded to normal climatic conditions, La Niña events and El Niño events, respectively. Abnormal climatic events change the range of cold and warm water in the fishing ground of O. bartramii, thereby changing the distribution of the appropriate temperature range, and eventually moving the gravity centers of the fishing ground along northeast-southwest direction. When the El Niño events occurred, SST in the study areas decreased and the gravity centers of the fishing ground shifted to the southwest. When normal climate conditions and the La Nina events occurred, SST in the study area increased and the gravity centers of the fishing ground shifted to the northeast.

Abstract:By the technology of tissue energy density determination combined with residuals analyses, the energy accumulation of somatic and reproductive tissues and the allocation to reproduction in the female and male individuals of dwarf form of Sthenoteuthis oualaniensis in the south China Sea were analyzed. The results showed that:there was a significant difference in the tissue energy density between somatic and reproductive organs; and with the exception of nidamental gland, other tissues showed significant variations in the tissue energy density with the progress of maturation. The tissue energy was accumulated significantly in both somatic and reproductive tissues during the sexual maturation. For a given maturity stage, the proportion of somatic tissue energy was consistently larger than that of reproductive tissues. The relative energy accumulation of reproductive tissues of females increased significantly with maturation, while that in males increased rapidly from maturity stages Ⅰ to Ⅴ followed by a non-significant variation at stages Ⅵ and Ⅶ. At the advanced maturity stages, individuals of the dwarf form of Sthenoteuthis oualaniensis showed a better condition in both somatic and reproductive tissues. Further, residuals analyses indicated that a positive correlation was found between the residuals of each somatic tissue energy accumulation regressed on the mantle length and the residuals of reproductive tissues (combined nidamental gland, oviducal complex and ovary in females, while in males combined spermatophoric complex and testis) energy accumulation on the mantle length, suggesting that there was no energy trade-off between somatic and reproductive tissues during the sexual maturation. In combination, these lines of evidence indicated that energy for reproduction in the dwarf form of S. oualaniensis in the south China Sea is mainly derived from food intake, and there are sex-specific variations in the tissue energy density, energy accumulation and relative energy accumulation of both somatic and reproductive tissues.

Abstract:The Bohai tidal wave system was numerically simulated by FVCOM(finite volume coast and ocean model). Data from 19 tidal stations along the Bohai Sea coast were used to verify the simulation results, which are in good agreement with the measured results. Based on this, the main characteristics of M₄, MS₄ and M₆ of three main shallow water tidal constituents in Bohai Sea were further studied and compared with previous research results. The results show that:the propagation characteristics of M₄ and MS₄ are similar, and there are 5 amphidromic points, one of which rotates clockwise, while the other four rotate counterclockwise; and for the M₆ tidal constituent, there are 9 amphidromic points, two are clockwise and the other seven are counterclockwise.The amplitude of M₄ component can reach 25 cm near the shore, which is about 10% of the amplitude of M₂, followed by the amplitude of MS₄, and the amplitude of M₆ is the smallest, which is only about 18% of the amplitude of M₄.The amplitude distribution of shallow water tides is closely related to the seabed topography.

Abstract:In order to solve the problems of high crushing rate caused by carrying traditional feeding machine directly in the boat-borne shrimp pond bait device and the deviation of hull center of gravity greatly affecting the draught depth of propeller in the process of feeding, a balanced shaking system of special feeding device was designed. The system makes use of the motor to drive the eccentric wheel to rotate to produce the difference of the cycle change, and makes the feed box jitter as a whole through the compound action of several support frames, so as to ensure the uniform feeding and reduce the breaking rate of the feed at the same time. The whole jitter feeding mode with adjustable fixed fulcrum position of the system was adopted to realize the long distance lossless feed transportation, which solves the problem that the tail driving part of the hull changes too much waterline due to the change of the center of gravity position, and makes the driving efficiency of the propeller more stable. Through the mathematical model of the shaking system, the optimal eccentricity of the vibration system is obtained. The optimal point position analysis of the squeezing device bracket is carried out by the torque balance equation. The motor energy consumption test and the design of the rotating bracket and the box slope were carried out. The calculation and analysis show that when the eccentricity is 1.2 mm and the fulcrum position is (-40, 0), the DC motor is used as the vibration source motor with the rated speed of 2 600 r/min. The actual working power is lower than 80 W, and the feeding rate is close to the average value of 1.63 kg/min. The field test shows that compared with the bait tank at the rear part of the boat, the variation of full load and no load draught in the driving part is reduced from 10.2 cm to 7.3 cm, and the average working speed of the feeding device is 1.03 m/s, the feeding was uniform and the crushing rate is low. The system is suitable for field environment, with low cost of production and maintenance, simple and reliable structure, and it is easy to popularize and apply, and has high practical value.

Abstract:In order to study the effect of dietary replacement of fish oil by vegetable oil on the taste quality of Chinese mitten crab, vegetable oil[W(soybean oil):W(rapeseed oil)=3:1] was used to replace different levels of fish oil (0%, 50% and 100%) to make three kinds of feeds with equal nitrogen and fat (F1, F2 and F3, with F1 as control) to feed adult female crabs (mass 95±10 g) for 70 days. The proximate composition, the contents of free amino acids and taste nucleotide of the edible parts of the three groups of crabs, and the overall taste difference by electronic tongue were analyzed in combination with sensory evaluation. The results showed that the crude lipid content of meat, gonads and hepatopancreas of three groups of crabs had no significant difference. The crude protein content of hepatopancreas of F2 was significantly higher than that of F1 and F3, while the crude protein content of meat of F3 was significantly lower than that of F1 and F2. Compared with F1, the umami and sweet sensory intensity value as well as the total amount of taste nucleotides and equivalent umami concentration in the edible part of F2 were increased, whereas those of F3 were decreased. Moreover, the content of umami and sweet amino acids of gonads and hepatopancreas of F2 were also increased. The above results showed that replacement of fish oil by 50% vegetable oil in feed not only improved the nutritional quality of Chinese mitten crab, but also enhanced its taste quality, which provided a reference for the improvement of the taste quality of cultured Chinese mitten crabs and the development of fish oil substitute sources in fattening feed.

Abstract:Vibrio parahaemolyticus biofilm formation in the food factory environment was studied, in order to prevent and control the biofilm pollution effectively. The different vibration modes of food processing equipment (such as horizontal rotary vibration, bevel vibration and vertical rotary vibration) were simulated to investigate Vibrio parahaemolyticus formation process on the surfaces of glass and stainless steel for 72 h, and the effect of vibration on the biomass, architecture and extracellular polymeric substances of biofilm was analyzed. The results showed that:the biofilm formation under shaking cultivation decreased significantly; the biomass of biofilm was the least under vertical rotary vibration; the biomass of biofilm on the stainless steel surface is greater than that on glass surface under same shaking cultivation; the biofilm formation was reduced with the increasing of horizontal rotation speed; the vibration caused the biovolume decreased, and the porosity and homogeneity increased, the architecture of biofilm dispersed; and the amount of extracellular polysaccharides and extracellular proteins of the biofilm decreased. All results show that different vibration modes have different effects on the biofilm; the selection of the vertical rotary vibration mode out of the three vibration modes can reduce and inhibit the growth of the biofilm effectively; the vibration cause the reduction of exopolysaccharide and protein, affecting the structural characteristics such as porosity and homogeneity; and the structure and formation of biofilm becomes simple and decrease.