Abstract:The swimming crab, Portunus trituberculatus is a commercially important mariculture species in east coast regions of China. Molting is an important physiological process for the growth of P. trituberculatus and estrogen related receptor (ERR) may be involved in the molting regulation. The present study was designed to investigate the expression differences of estrogen related receptor (PtERR) in various tissues of Portunus trituberculatus during molting cycle by quantitative real-time PCR (qRT-PCR). The results showed that, for the tissue-specific expression analysis, the Y-organs and gill had the highest expression levels of PtERR, and the second highest expression levels were found in eyestalk and stomach, while the lower expression levels were found in three kinds of muscle tissues and the triangular membrane at stage C. The expression levels of PtERR varied significantly in any specific tissue at different stages of molting for 13 types of tissues. The expression pattern of PtERR-mRNA showed a significant increasing trend from stage AB to stage E in Y-organ; the pattern of "low-high-low" was found ifor the PtERR-mRNA of thoracic ganglia and eyestalk; the trend of "high-low-high" was found in mandibular organ; PtERR-mRNA had the significantly increasing trend in cheliceral muscle, appendage muscle and triangular membrane. However, the trend of "high-low-high" was found in abdominal muscle. In terms of digestive and metabolic organs, the expression levels of PtERR-mRNA increased firstly and then declined throughout the molting cycle in stomach, hepatopancreas and gill, and the peak value of PtERR-mRNA was detected at stage D; for intestinal tract, the highest expression level of PtERR-mRNA was found at stage D, and lower expression level was detected at stage C and stage E; finally, the expression level of PtERR-mRNA increased significantly in heart from stage AB to stage E, which was around two-fold increase for each stage. In summary, PtERR is mainly expressed in Y-organ, gill, eyestalk and stomach, which may be involved in the regulation of molting process, cell proliferation and energy metabolism.

Abstract:Tyrosinase (TYR) is a key and rate-limited enzyme in melanin synthesis pathway. Black spots are one of the main body color characteristics in Oujiang color common carp (Cyprinus carpio var. color). In this study, the total of the fifth generations of Oujiang color common carp (F₅) were used to observe the variation and selective pressure sensitivity of tyrosinase (TYR) gene among the five exons in this gene and among the five body color patterns in this fish. The results showed: the nucleotide variation rate and the number of their positive selection sites in exon 1 and exon 5 were higher than those of the other three exons, indicating these two exons were more easily subjected to selective pressure. The ratios (ω) of d_N/d_S of the five exons were all less than 1 (0.10-0.67), which demonstrated there was purifying selection conducted in tyrosinase gene. Similarly, the ratio (ω=0.12-0.23) illustrated there was also purifying selection in the five body color patterns of Oujiang color common carp. The amino acid site analysis of selection pressure using the Codeml models (M2a and M8) in the software PAML indicated that there were more positive selection sites in the fish without black spots than the fish with black spots, although there was no significant difference (P>0.05). Furthermore, some amino acid sites were also found with more easily positive selection than the other acids in tyrosinase gene. Generally, tyrosinase gene was conservative in evolutionary process and mainly subjected to purifying selection in Oujiang color common carp, and no significant selection pressure on this gene was found under artificial selection in this fish.

Abstract:The gene sequences of cytochrome oxidase subunitⅠ, cytochrome oxidase subunit Ⅱ and cytochrome oxidase subunit Ⅲ of 12 individuals of Bagarius yarrellis were obtained by PCR technique and clone methods; MEGA5.0 program was used to analyze their phylogeny and polymorphism. It can be seen from the results that the total length of COⅠ gene sequence was 1 551 bp, as well as 12 individuals showed 9 haplotypes and 13 mutation sites; the total length of CO Ⅱgene sequence was 691 bp, as well as 12 individuals denoted 5 haplotypes and 5 mutation sites; the total length of CO Ⅲ gene sequence was 784 bp, as well as 12 individuals showed 7 haplotypes and 8 mutation sites. Phylogenetic analysis reveals that B. yarrelli has a certain sequence homology with 14 species of Sisoridae. The structured Minimum Evolution (ME) phylogenetic tree from sequences of COⅠ, COⅡ and CO Ⅲ showed that B. yarrelli exists in the same branch with Glyptothorax sinense, Glyptothorax fukiensis, Glyptothorax trilineatus and Gagata dolichonema, which indicates that B. yarrelli has a close genetic relationship with species of Glyptothorax and Gagata.

Abstract:To investigate the regulatory mechanism of gonad inhibiting hormone (GIH) during gonadal development of Litopenaeus vannamei, expressions of gonadal development related genes(DMC1, VASA and VTG) were detected by real time fluorescent quantitative PCR after eyestalk ablation, or injection of the eyestalk extract. The results showed that DMC1 and VASA were only expressed in the testis and ovary in L. vannamei. DMC1 mRNA expression decreased significantly in testis and ovary after eyestalk ablation (P<0.05), while it increased significantly after eyestalk extract hormone injection (P<0.05). On the contrary, VTG expressions in ovaries, as well as VASA expressions in testis and ovaries increased significantly after eyestalk ablation, but decreased after eyestalk extract hormone injection. Results showed that eyestalk extract hormone affected the development of gonad by affecting the expression of the reproductive related genes.

Abstract:A strong pathogenic bacterial strain Jxsks1 was isolated from grass carp, Ctenopharyngodon idllus. The pathogen was identified as Aeromonas hydrophila based on the physiological and biochemical analysis and the sequencing of housekeeping gene 16S rDNA and gyrB. The LD₅₀ of the bacteria infecting the grass carp via intraperitoneal injection was 2.3×10³ CFU/g. The results of genetic typing by ERIC-PCR (enterobacterial repetitive intergenic consensus PCR)-fingerprinting showed that it was a type of A. hydrophila which has not been reported before. The distribution patterns of six virulence genes, including aerolysin (aerA), heat-labile cytotonic enterotoxin (alt), heat-stable cytotoxic enterotoxin (ast), elastase (ahpB), lipase (lip) and flagella (fla), were tested by PCR method and the results showed that its virulence-gene pattern was aerA⁺, alt⁺, ast⁺, ahp⁺, lip⁺, fla^-. The drug susceptibility test of 28 antibiotics by paper extension method showed that the strain was susceptible to quinolones, aminoglycoside, tetracyclines, chloramphenicol, the second and the third generation cephalosporins, intermediately sensitive to nitrofurans, macrolides and polypeptides, but resistant to the first generation cephalosporins, penicillins, sulfamethoxazole compound and lincomycin.

Abstract:We harvested 15 individuals Takifugu in Luchao Seaport of the East China Sea, 11 of them were both spotted and striated on the dorsal skin, supposed to be the hybrids of Takifugu. DNA barcoding COⅠgene showed these 15 individuals of Takifugu are most closed to Takifugu flavidus and T. bimaculatus, then to T. oblongus, then to T. obscurus. The exon-primed intron-crossing (EPIC) marker which is based on the polymorphosis of intron sequences, showed these fishes are closed to T. flavidus, T. obscurus or T. bimaculatus. We further compared the body color pattern and ray numbers of dorsal fin, anal fin and pectoral fin of there 15 individuals, and found these morphological features in ten individuals of them were not same as those in known Takifugu species, the morphological features seems to be the result of species hybrid. Taken together with proofs from the molecular and morphological data, we can say at lease some of these fish are the hybrids of T. flavidus with T. bimaculatus, or T. obscurus, or T. oblongus. It is possible as well that some of them are the hybrids of T. oblongus with T. flavidus, or T. bimaculatus, or T. obscurus. Our result showed that occurrence of hybrid among Takifugu in East China Sea, even so far we can not determine whether the species hybridization was wild or artificial.

Abstract:This anatomical, biochemical and the ultrastructural study on the sound production system in marbled rockfish Sebasticus marmoratu is focused on characteristics of the parvalbumin and the ultrastructure of the sonic muscle. The results reveal that the molecular weight of parvalbumin is about 10~14 ku in both sonic muscle and the white muscle of the fish. The TEM micrograph reveals the ultrastructural characteristics of the muscle fibers, among that the T system/SR of the sonic muscle are typically at both the Z-lines and A/I junctions, but are at the level of the Z-line only in the white muscle fibers. Sarcoplasmic reticulum and cell membranes in the sonic muscle fibers are wider and more developed than those in the white muscle. Moreover, there are more mitochondria which are crowded together in the sonic muscle cell, by contrasting, that are relatively fewer and are scattered in the white muscle cell. Our results suggest that: in marbled rockfish, the parvalbumin may not be playing an important role in the fast contraction of the sonic muscle, but the wide sarcoplasmic reticulum and enhanced cell membrane, the T system/sarcoplasmic reticulum, these ultrastructural advances may ensure the rapid contraction function of the sonic muscles for sound production. The feature of large amount of crowded mitochondria in the sonic muscle cells may enable the fish to produce the sound.

Abstract:The Whitmania pigra Whitman has been used as a traditional Chinese medicine in cardiovascular diseases and other chronic diseases for centuries. Over the last few decades, however, overfishing and environmental pollution have caused dramatic declines in natural stocks of Whitmania pigra, and its production is low and unstable. An analysis of the reproductive ability and growth traits of the Whitmania pigra is valuable for its artificial farming. In the present study, the reproductive ability and growth traits for the wild leech were studied in the laboratory. A total of 50 wild individuals of Whitmania pigra with clitellum were kept in 50 plastic boxes full of wet soil, as a result, a set of 44 individuals (12.91±5.21 g) laid cocoons. The range of cocoons produced by every parent leech was from 1 to 4, and the mean number of cocoons was 2.45±0.88, and the lost weight of leeches was 52.38%±9.57%. However, the mean number of cocoons (2.80±0.79 per leech) produced by the parent leeches over 10.00 g was higher than the mean number of cocoons (1.71±0.62 per leech) produced by the leeches below 10.00 g. The average weight and the long diameter of the oval cocoon were (0.8735±0.3784)g and (2.2027±0.4936)cm, respectively. The hatching number of cocoons were between 1 to 59 and the mean number was 27.61±10.81. According to the number of cocoons and hatchings for each leech, the hatching numbers were 27 to 137 with 65.25±34.91 hatching per leech. The weight of juvenile leech increased from (0.0209±0.0028) g to (0.2981±0.0905) g after 21 days in laboratory conditions. The R_GR was higher in the beginning, then it increased with water temperature, and the R_GR was the highest when the water temperature was 26.00℃. Our results provide basic information for reproductive ability and growth traits of the Whitmania pigra Whitman.

Abstract:The Yangtze River estuary is an important self-adjusting and feeding ground for juvenile Chinese sturgeon in the migration to sea process. It is very helpful and meaningful for the protection of Chinese sturgeon via studying the long-term tendency for recruitment features of its juveniles in this area. In this study, we focused on the analysis of the fluctuation features of recruitment for juvenile Chinese sturgeon according to the survey data on the amount and biological characteristics of juvenile Chinese sturgeon during 2005-2013. The results showed: (1) the earliest occurrence time, the final departure time and time span of juvenile in the Yangtze River estuary were at the high level fluctuation; (2) recruitment of juvenile had general clear decrease and fluctuated strongly in different years; (3) Analysis of Variance (ANOVA) showed years had a significant effect on the mean of total length and body weight of juvenile (P<0.05); (4) the results of correlation analysis indicated that the mean of total length had a high association with the final departure time of juvenile (R=0.7196, P<0.05), which might be used to explain why the mean of total length in 2007 was significantly higher than the normal level.

Abstract:A feeding experiment was conducted to assess the dietary phenylalanine requirement for fingerling grass carp (Ctenopharyngodon idella). Seven isonitrogenous diets with graded levels of phenylalanine ranging from 0.82% to 2.12% (% Dry matter) were fed to triplicate groups of fish with an average initial body weight of 13.21g for 56 days, respectively. The results show that weight gain rate, feed efficiency and protein retention efficiency increased with increasing of dietary phenylalanine level from 8.2 g/kg to 12.0 g/kg, but appeared to keep stable with further increasing to 21.2 g/kg. And whole fish body protein was affected significantly by dietary phenylalanine level (P<0.05). However, fish survival rate, viscerasomatic index, hepatosomatic index, condition factor and whole fish body moisture, lipid and ash were not affected significantly by dietary phenylalanine level (P>0.05). The broken-line regression analysis with weight gain, feed efficiency and protein retention efficiency as the criteria indicated that the requirements of dietary phenylalanine for fingerling grass carp were 12.73 g/kg, 12.20 g/kg and 12.55 g/kg of dry diet respectively. In conclusion, the dietary phenylalanine requirement for fingerling grass carp was estimated to be 12.20-12.73 g/kg dry diet(with 5.5 g/kg tyrosine in diet), and 3.39%-3.54% of the dietary crude protein.

Abstract:A 10-week feeding trial was conducted to investigate the dietary lysine requirement of blunt snout bream (Megalobrama amblycephala) with initial body weight of 52.49±0.18 g (size Ⅰ) and 101.85±1.85 g (size Ⅱ). Six isonitrogenous and isoenergetic semi-purified diets were formulated that containing graded lysine levels (1.29%, 1.71%, 2.09%, 2.48%, 2.88% and 3.27%of dry weight). The results showed thatweight gain rate (WGR), specific growth rate (SGR) and protein efficiency ratio (PER) in fish of size Ⅰ fed with diets containing 2.88% and 3.27% lysine were significantly higher than that of the control group, while the reverse pattern was observed in feed conversion ratio (FCR) and feed intake (FI). The 2.48% lysine diet significantly increased SGR and decreased FCR, meanwhile, 3.27% lysine diet significantly increased SGR and FI in fish of size Ⅱ.The diet with 2.88% and 3.27% lysine significantly increased body fat content in fish of size Ⅰ and size Ⅱ, respectively.Significantly decreased ALT in plasma of size Ⅰ and Ⅱand increased Urea of size Ⅰ were observed fed with 2.48% lysine diet, while increased ALB, TP and GLB in plasma content of size Ⅱ fed with 3.27% lysine diet, which indicate that proper lysine in diet might protect the liver and enhance the metabolism and immunity ability compare with the control group. The 2.48%, 2.88% and 3.27% lysine diet significantly increased the plasma lysine content of size Ⅰ and Ⅱ, and decreased the plasma arginine and total essential amino acids content of size Ⅰ. Based on the broken-line regression analysis of SGR, the optimal dietary lysine requirements of size Ⅰ and Ⅱ were estimated to be 2.07% and 2.19% (6.27% and 6.63% of dietary protein), respectively.

Abstract:Effects of different levels of factors including salinity (3, 6, 9), light intensity [20, 40, 60 μmol/(m²·s)] and temperature (10, 20, 30℃) on the growth, ARA and EPA contents in diatom Cyclotella sp. SHOU-B108 were studied by orthogonal experiments. The results showed that the highest biomass (dry weight) of Cyclotella sp. was obtained in the treatment of salinity 6, light intensity 40 μmol/(m²·s) and temperature 30℃ on 10th day. There were significant interactions among salinity, light intensity and temperature on the ARA and EPA contents in Cyclotella sp.. Temperature was the main factor influencing the ARA and EPA contents of the diatom. Lower salinity (3) combined with higher temperature (30℃) was beneficial to accumulating ARA but high light intensity (60 μmol/(m²·s)) was beneficial for accumulating EPA in the cells of Cyclotella sp.. It is therefore suggested that different fatty acids in the cell display different reflections of the same environmental change, and Cyclotella sp. SHOU-B108 cells with specific high nutritional value could be harvested by optimizing the salinity-light intensity-culture temperature combinations.

Abstract:The contrast experiment was carried out about the effects of Bacillus subtilis and spinach(Ipomoea aquatica Forsk) on the water quality improvement in the pond during the co-farming of rice-crayfish-finless eel. The results showed that Bacillus subtilis and spinach both improved water quality, increased DO and decreased pH of water.Bacillus subtilis had better effects in the decreasing of the NH₄⁺-N, NO₂^--N, TN, TP than spinach of three density groups with the highest level of degradation rate by 68.06%, 86.49%, 49.96%, and 58.82% respectively. Generally, the spinach with 20% of density degraded the level of NH₄⁺-N, NO₂^--N, TN, TP by 63.00%, 88.39%, 53.12 and 49.02% most efficiently. In sum, the combination of Bacillus subtilis and spinach with the 20% density in the pond during the co-farming of the rice-crayfish-finless eel was better.

Abstract:Phytoplankton community structure in three regions of Gehu Lake was investigated and analyzed from July in 2013 to June in 2014.The three regions include inside and outside of bio-manipulation pen and demonstration project area. A total of 158 phytoplankton species, belonging to 7 phyla and 80 genera, were identified.There were 11 dominant species of phytoplankton in inside of bio-manipulation pen, 9 dominant species of phytoplankton in outside of bio-manipulation pen and 5 dominant species of phytoplankton in demonstration project area. The main dominant species inside and outside of bio-manipulation pen throughout the year was: Microcystis incerta, and in demonstration project area was Melosira granulate var. angustissima.The order of standing crop is: outside of bio-manipulation pen > inside of bio-manipulation pen>demonstration project area. LSD from multiple comparison showed that density of phytoplankton had significant difference between inside and outside of bio-manipulation pen(P<0.05).Extremely significant difference was found between inside of bio-manipulation pen and demonstration project area(P<0.01), between outside of bio-manipulation pen and demonstration project area(P<0.01). Biomass of phytoplankton had extremely significant differences between inside of bio-manipulation pen and demonstration project area(P<0.01), between outside of bio-manipulation pen and demonstration project area(P<0.01).There was no significant difference between inside and outside of bio-manipulation pen. RDA and Pearson showed that water temperature(WT), Chl.a and COD_Mn were the main environmental variables affecting the community structure of phytoplankton.

Abstract:To describe the status of benthic animal communities and its spatial and temporal distribution in Taibo Lake, we surveyed quarterly the benthic animals in Taibo Lake from May 2013 to May 2014. 11 species of benthic animals belonging to 10 genera were collected in 7 sampling sites. Chironomus plumosus, Nephtys polybranchia and Limnodrilus hoffmeisteri were dominant species in Taibo Lake, accounting for 83.53% of total animal number. Density and species mumber of benthic animals changed significantly with seasons. The highest density of benthic animal appeared in Spring, and it was 1019.64 ind/m². Winter and Autumn were 437.5 ind/m² and 287.5 ind/m², Summer was 264.29 ind/m². The highest biomass appeared in Winter and Summer with 87.53 g/m² and 86.32 g/m². Autumn and Spring were 47.26 g/m² and 35.41 g/m².Diversity analysis indicated that some various index absolute values are low.There was significant difference in benthic animal number and species mumber that were collected in 7 sampling sites The results showed that the community structure of benthic animals was simple and the total species had obviously seasonal differences in Taibo Lake. The water eutrophication is serious.

Abstract:Macro algae contribute to kelp forest C/N nutrient circulation primarily as detritus, maintaining high primary productivity in local food web. Changes in overall δ¹³C, δ¹⁵N signatures and C content, N content, C/N ratios of five dominating kelp(U. pertusa, C.tenuissima, G.livida, S.vachellianum and H.fusifarme) litters in litter bags during degradation were examined. Kelp litters completely rotted over 42 days in the field near Gouqi Island, both organic C content, N content and C/N ratios were depleted after decomposition, as for δ¹³C and δ¹⁵N, there was no significant variation. We divided the whole kelp degradation into two periods which are leaching degradation period (0-11 days) and microbiological degradation period (11-42 days). Furthermore, trophic level changes by 0.4 in four benthonic herbivores as a result of degradation of macroalgae. It's a significant deviation in macroalgae based kelp bed ecosystem food web establishment.

Abstract:In this study, we analyzed the reproduction of the Humboldt squid (Dosidicus gigas) based on 2 489 individuals collected off the Peruvian waters during January 2008 to October 2010 by Chinese jigging vessels. The number of females of D. gigas was significantly greater than that of males in the study area and the ratio of female to male was 3.99:1. The occurrence of mature individuals in each month showed that D. gigas spawn all the year round, although only 10.4% females and 21.3% males matured among the total samples. Nidamental length showed significant power correlations with nidamental weight. Nidamental gland and gonad somatic index increased with gonad maturity gradually from gonad maturity Stage Ⅰ to Ⅳ, but slightly decreased at Stage Ⅴ due to mating and spawning (P<0.05). The relative frequency distribution for mantle length classes fitted Logistic model. This showed that mantle length at maturity of D. gigas was 539 mm for females, and 507 mm for males.

Abstract:To better understand the effects of environmental variables on catch rate of yellowfin tuna (Thunnus albacrares) is beneficial to increasing the yellowfin tuna catch rate and reducing the bycatch rates of other non-target species in the longline fisheries. In this study, the catch rate of yellowfin tuna and environmental variables were collected from longlining surveys in waters near Cook Islands from Sep. 8^th, 2013 through Dec. 31^th, 2013, including hook depth data, temperature, chlorophyll-a concentration, current, operating parameters, and catch data. Stepwise regression of DPS was used to develop the hook depth calculation model. Statistics and clustering analysis were used to analyze the effects of environmental variables on yellowfin tuna catch rate. Results showed that the depth, temperature, chlorophyll-a concentration, east-west direction current, south-north direction current, vertical and horizontal direction current related with the high catch rate of yellowfin tuna were 120-160 m, 21-22℃, 0.32-0.36 μg/L and 0.40-0.44 μg/L, -0.20-0.10 and 0.00-0.20 m/s, -0.10-0.20 m/s, -0.10-0.06 m/s and 0.02-0.06 m/s, 0.20-0.30 m/s, respectively. Results suggest that the hook numbers should be increased in ranges of the water depth, temperature, chlorophyll-a concentration, and current related with the high yellowfin tuna catch rate when fishing in the waters near Cook Islands and targeting yellowfin tuna.

Abstract:In this study, the gel strength, whiteness and myosin thermal denaturation temperature, of the silver carp surimi by different pressures (0, 100, 200, 300, 400, 500 MPa, dwell time: 10min, temperature: 25℃) were first investigated. Then the total bacterial amount and total volatile basic nitrogen (TVB-N) of surimi were analyzed during storage at 4℃. The results showed that the gel strength increased firstly and then decreased with increasing pressure and reached maximum value at 400 MPa. The whiteness of surimi increased significantly with increasing pressure, but increased slowly at 400-500 MPa. DSC thermogram showed significance between different processing pressures for thermal denaturation temperature of surimi myofibrillar proteins. Storage under 4℃, most of the bacteria could be inactivated by ultra-high pressure treatments and the TVB-N was restrained. The shelf life of surimi was prolonged with the enhancement of high pressure. In conclusion, the ultra-high pressure treatments could not only improve the quality of silver carp surimi, but also prolong the shelf life. The ultra-high pressure treatment has good application prospects for processing and production of silver carp surimi.

Abstract:Dielectric and thermal properties of shrimp (Litopenaeus vannamei) surimi and surimi-soybean compound were measured in the temperature range from 10℃ to 80℃. The results suggested that dielectric constant and penetration depth decreased as temperature increased, while loss factor increased with increasing temperature. The addition of soybean protein isolate (SPI) compound depressed dielectric constant at a given temperature and frequency, but had no significant influence on loss factor and penetration depth. Density of shrimp surimi and surimi-soybean compound decreased with increasing temperature, and specific heat capacity, thermal conductivity and thermal diffusivity increased as temperature increased. The addition of soybean protein isolate emulsion also had an impact on the thermal properties. Density and specific heat capacity decreased with the increase of concentration of soy protein isolate emulsion. Established equations by comparing the model prediction and experimental data obtained can predict the conditions for a given temperature.