Abstract:In order to explore the food composition of mantis shrimp Oratosquilla oratoria, we analyzed carbon and nitrogen stable isotope ratios(δ¹³C and δ¹⁵N) in O. oratoria and their preys in Honghai Bay in May 2015. The results showed that the average δ¹³C and δ¹⁵N values of O. oratoria were -17.1‰±0.5‰ and 12.7‰±0.7‰, in range of -18.1‰--16.3‰ and 10.9‰-13.5‰, respectively. Preys of O. oratoria were fishes, shrimps, bivalves, crabs and copepods. Bivalves were the most important prey of O. oratoria by taking 38.6% on the average of the total food sources, followed by crabs(average 22.9%), copepods(average 16.0%), shrimps(average 13.6%) and fishes(average 8.9%). The average trophic level of O. oratoria was 3.01±0.22, on top of all their preys, and fishes, shrimps, bivalves, crabs as well as copepods' trophic level were 2.98±0.15, 2.89±0.16, 2.00±0.20, 2.78±0.21 and 1.77±0.12 respectively. Statistical analyses revealed significant positive correlation between the body weight and δ¹⁵N value of O. oratoria, indicating that the body size affected the trophic level of O. oratoria.

Abstract:Postcopulatory sexual selection is a common phenomenon in polyandry species. The mechanism of postcopulatory sexual selection is complicated, and it is the key and difficult topics in sexual selection. Rapana venosa is one of the most important commercial molluscs in China, whose females mate with multiple males. In this study, paternity analysis was performed in three families of R. venosa using microsatellite markers and behavior observation. Multiple paternity was observed in all the three families, suggesting that R. venosa was genetic polyandry. There was no correlation between six morphological parameters of males and paternity ratios, and no correlation between the mating duration and paternity ratios. The results showed that the first mating male had most progeny and the last mating male had least progeny. R. venosa exhibited first-male sperm precedence. This pattern of sperm precedence was consistent with the hypothesis of "topping off", in which a female accepts a large amount of sperm from her first mate, and, if additional space remains in her spermathecae, she then seeks additional mates until she has no need for further sperm. This study provides important information for the studies on mechanism of postcopulatory sexual selection in marine invertebrates.

Abstract:In order to investigate the effect of temperature and salinity on Haliotis ovina embryonic and larval development in Wenchang Hainan during November to December, 2013, we used the artificial domestication of wild H. ovina as experimental material, and single or double factor combination method with the temperature and salinity to design the experiment. The results showed that: the hatching rate and the survival rate of H. ovina were significantly affected by temperature and salinity. When the temperature was 28℃, the embryonic development time was the shortest and the hatching rate was the highest. When the temperature was 26℃, the larval development time was the shortest and the survival rate was the highest. The range of suitable temperature for embryonic development was 24-28℃, and the optimal temperature was 26-28℃. The range of suitable temperature for larval development was 26-30℃, and the optimal temperature was 26-28℃. When the salinity was 24, the embryonic development time and the larval development time were the shortest but the hatching rate and the survival rate were the lowest. The hatching rate and the survival rate were the highest at 30 and 32, respectively. The range of suitable salinity for embryonic development and larval development was 28-32, and the optimal salinity was 30-32. There was no siginificant effect of temperature and salinity interation experiments on the hatching rate, but there was siginificant effect on the survival rate. Based on the response surface model, the hatching rate and the survival rate reached the maximum(95.32%, 81.20%) when the 2-factor combination was 24.61℃ and 32, with the desirability value being 0.848. The studies indicated that the H. ovina embryonic development and larval development had different sensitivity to different temperature and salinity, The high temperature and high salinity were better tolerated than the low temperature and low salinity.

Abstract:In order to determine the ecological function of seagrass Zostera marina L. in sea cucumber culture, water temperature and dissolved oxygen in the eelgrass bed of a sea cucumber pond were determined and compared with the adjacent sandflat. Food sources used by sea cucumber Apostichopus japonicas were determined by comparing their stable isotope signatures(δ¹³C, δ¹⁵N) with those of food source. Proportions of different carbon sources were estimated using the SIAR mixing model on δ¹³C and δ¹⁵N values. The results showed that water temperature at eelgrass patch bottom was 0 to 0.33℃ lower than the naked sandflat. Surface and bottom dissolved oxygen showed no differences between low eelgrass coverage(0 to 25%) area and sandflat, while in area with mid-to-high eelgrass coverage, resolved oxygen was 0.12 mg/L~0.62 mg/L higher in surface water. Bottom dissolved oxygen was lower in mid-to-high eelgrass coverage(0 to 0.38 mg/L). Stable isotope signatures δ¹³C and δ¹⁵N of sea cucumbers A. japonicus was -15.27% and 8.11‰, which differed from those in adjacent coastal seagrass habitat(-20.12% and 10.95‰). A strong role of Z. marina matter as food sources was indicated from the estimation of SIAR mixing model. The model gave higher upper and lower limits of 0.95 credibility interval(CI)(from 13% to 52%) for Z. marina relative to microphytobenthos, particle organic matter POM and epiphyte, for which 0.95 CI ranged from 4% to 49%, 23% to 39% and 0 to 22%, respectively. However in adjacent coastal seagrass bed A. japonicus showed different stable isotope signatures with -20.12‰ and 10.95‰ for δ¹³C and δ¹⁵N, respectively. 0.95 CI of SPOM and brown seaweed ranged from 24% to 54% and 1% to 53% while seagrass Z. caespitosa matter only contributed to 0~27%. These results demonstrate that Z. marina could reduce the bottom temperature in the pond and increase surface dissolved oxygen. Cultured A. japonicus consume relatively higher amounts of Z. marina than other organic sources in this pond. This implied the importance of seagrass habitat in the pond environment. The importance of seagrass habitats in sea cucumber pond was discussed and the necessity and feasibility to transplant seagrass to sea cucumber pond was highlighted.

Abstract:Focusing on discovery and cloning of important functional genes, we summarized a set of bioinformatics methods to efficiently dig for profound RNA-seq information. The results showed that 8L:16D, 12L:12D and 16L:8D had 5 807 622, 6 147 140 and 6 116 872 Clean reads, respectively. Comparison between the sequencing data from 8L:16D, 12L:12D, and 16L:8D revealed 200 differentially expressed genes(DEG). The DEG GO functions in the transcriptome library were broadly divided into biological process, cellular component and molecular function categories of 42 branches. Data in the transcriptome could be divided into 22 classes taking the KEGG database as a reference, according to the metabolic pathway, including glycocysis/gluconeogenesis, phototransduction, calcium signaling pathway, and vascular smooth muscle. This study not only conveyed more useful information of CNSS function in flounder, but also provided multi-level information of phototransduction in teleost.

Abstract:In order to develop a new variety of Pyropia with thin blade, which is suitable for cultivation in the aquaculture areas with high temperature along the coast of South China, the blades of the wild-type strain(PC-WT) of Pyropia chauhanii were irradiated with ⁶⁰Co-γ rays and cultured at a high temperature(30℃) for 25 days, and then the improved strain of PC-M was obtained. Subsequently, PC-M was compared with PC-WT for high-temperature resistance, growth, contents of major photosynthetic pigments, the releasing ability of monospores and conchospores. The results showed that the rates of survival, division and rhizoid germination of conchospores were not significantly different between PC-M and PC-WT at 18 and 23℃, but the survival rates were 250.7% and 305.4% higher, the division rates were 42.4% and 67.1% higher, the rhizoid germination rates were 86.6% and 175.3% higher in the former than those in the latter at 27 and 29℃, respectively. The F₁ gametophytic blades of PC-M and PC-WT were cultured at 23℃ for 30 days and then cultured at 18, 23, 27 and 29℃ for another 10 days, in the group of 18, 23 and 27℃, the absolute growth rates of PC-M blades were 5.1, 5.3 and 7.5 times those of PC-WT, and the specific growth rates were 1.3, 1.3 and 1.8 times those of PC-WT, respectively. The apical and middle parts of PC-WT blades were disintegrated because of releasing a large number of monospores after being cultured for 15 days at 27℃ and 10 days at 29℃, and only the basal parts of the blades remained intact. On the other hand, PC-M blades grew rapidly with normal color and shape without releasing monospores, just slightly curled after being cultured for 30 days. In addition, the contents of three major photosynthetic pigments(chl. a, PE and PC) and the conchospore numbers in PC-M at a suitable temperature(23℃) were 39.4%, 209.8%, 94.8% and 36.7% higher than those of PC-WT, respectively. Meanwhile, the thickness of blades of PC-M was 31.6% thinner than that of PC-WT. The above results indicated that PC-M has thinner blade, higher contents of the major photosynthetic pigments, faster growth speed, higher-temperature resistance, larger number of conchospore release and no monospore release as compared with PC-WT. It is therefore potential to be developed into a new variety suitable for cultivation along the coast of South China.

Abstract:We cloned full length cDNA of ELOVL6 gene(GenBank accession KT779219) in Eriocheir sinensis using genetic homology and RACE methods.The full sequence was 2247 bp, including of 235, 873 and 1139 bp of 5'-URT, ORF and 3'-URT. ELOVL6 gene specified a protein of 290 amino acids which got all of ELOVL features: six transmembrane-spanning regions, one diagnostic histidine box HXXHH motif, several conservative regions and ER retention signal KXKXX.The phylogenetic tree estabilshed by the Neighbor Joining method showed that ELOVL2 is clustered closely with ELOVL5 and ELOVL6 is clustered by itself. At the same time, ELOVL6 of Chinese mitten crab is the closest to the ELOVL6 of Litopenaeus vannamei. Its biochemical function characterized by heterologous expression showed that it caused reduction of C16:0 and C16:1n-7 and increase of C18:0 and C18:1n-9, while produced new product C18:1n-7. Relative gene expression levels of ELOVL6 mRNA in nine tissues and three kinds of different lipids formula feed by quantitative real-time PCR.The results suggested that ELOVL gene was expressed in all of these tissues and it was highest in the hepatopancreas, while lower in the cranial ganglia and thoracic ganglia, and trace in the other tissues. Real-time Q-PCR also revealed that on one side, levels were expressed in hepatopancreas, ovary, transcripts and muscle, on the other side, levels were highest in the hepatopancreas when fed the SO diet compared with the FO diet and FO/SO diet.The results above showed that E. sinensis ELOVL6 could catalyze the production of C16 long-chain fatty acids including both saturated and monounsaturated fatty acids which laid a base for PUFA biosynthesis and its function was influenced by different levels of lipids. Thus, it provided a foundation for fatty acids biosynthetic pathway and its regulation mechanism.

Abstract:In order to define the potential pathogens causing fulminant illness of Procambarus Clarkii in Dangtu County, Anhui Province, pathogens were isolated from the moribund Procambarus Clarkii. A dominant strain named XLX1 was isolated from the hepatopancreas and was confirmed to be pathogenic to Procambarus Clarkii by artificial challenge test. The XLX1 isolate was identified as Citrobacter freundii by means of the morphology, physiological and biochemical characteristics and 16S rRNA gene sequencing. The antibiotics sensitivity, adhesin-carrying genes and cell adhesion of XLX1 isolate were further detected. The results showed that the XLX1 isolate was sensitive or medium sensitive to cefotaxime, gentamicin, amikacin, neomycin sulfate, enrofloxacin, norfloxacin and teicoplanin, but resistant to other 7 kinds of antibiotics. The XLX1 isolate carried adhesin genes cfa and ure clusters. It was found that ureABC structure gene and ureD key accessory gene was relatively conservative by the sequences analysis. The nucleotide and amino acid homology of former respectively ranged from 93.2% to 98.3% and 91.7% to 97.4%, and the latter ranged from 90.8% to 98.3% and 94.7% to 98.7% between XLX1 isolate and reference strains. Compared with reference strains derived from patient, the 294th, 600th, 608th amino acids in UreABC structure protein and the 62 nd and 122 nd amino acids in UreD key accessory protein generated sense mutation amino acids from XLX1 isolate. XLX1 isolate adhered to the epithelioma papulosum cyprinid(EPC) cells mainly in aggregative pattern, and the average adhesive bacterial number was 29.8±5.3, which caused EPC cells lesion with the extension of adhesion time. This study may contribute to providing a theoretical basis for controlling aquatic animal disease caused by Citrobacter freundii.

Abstract:Catalase(EC 1.11.1.6) is an important antioxidant enzyme that protects aerobic organisms against oxidative damage by degrading hydrogen peroxide to water and oxygen. In the present study, the complete cDNA of Catalase in ark shell Scapharca broughtonii(named SbCAT) was cloned by RT-PCR and rapid amplification of cDNA ends technique, which contained 2181 bp. The cDNA consists of a 5' untranslated region(UTR) of 96 nucleotides, the 3' UTR of 654 bp, and an open reading frame(ORF) of 1431 bp, encoding 477 amino acid residues with 54 ku predicted molecular weight and the theoretical isoelectric point of 8.03. SbCAT amino acid sequence compared with the other animals compared 68%-96%.The deduced amino acid sequence of SbCAT has characteristic features of catalase family such as the catalase active site(₆₁FNRERIPERVV-HAKGAG₇₇), the catalase heme-ligand signature motif(₃₅₁RLFSYPDTH₃₅₉) and the three catalytic amino acid residues of His-72, Asn-145 and Tyr-355. In addition, SbCAT also has the conservative heme-binding pocket and NADPH binding sites. Quantitative real-time PCR(qRT-PCR) method was used to analyze the SbCAT mRNA expression characterization in tissues of normal ark shells. The results showed that SbCAT mRNA detected was expressed in six had a high similarity of and it was higher in the mantle and lower in the tissues of hepatopancreas and haemocyte. After Vibrio anguillarum and Staphylococcus aureus challenge, SbCAT expression was rather low in mantle with V.anguillarum challenged, and significantly up-regulated in other tissues. This results suggests that SbCAT may play an important role in the immune defense of S. broughtonii.

Abstract:Oligosaccharides could induce physiological responses of algae to defend attacks from pathogens. This study was designed to research the different responses of different growth stages of Pyropia haitanensis to agaro-oligosaccharide elicitor. Six growth stages including 50, 60, 80, 110 and 140 days P. haitanensis thallus and free-living conchocelis were selected to detect the release of hydrogen peroxide(H₂O₂) by(p-hydroxypheny1) acetic acid fluorometric method, expression of defense related genes(Phhsp70, Phrboh, Phsod, Phlox) by real-time quantitative RT-PCR, and volatiles changes by GC-MS after being elicited with agaro-oligosaccharides. The results showed that, without treatment with agaro-oligosaccharides, free-living conchocelis contains significantly higher levels of hydrogen peroxide and fatty-derived volatiles than those of the thallus. 100 μg/mL agaro-oligosaccharides can induce the quick outbreak of H₂O₂ of different growth stages of P. haitanensis, and thallus responded faster than conchocelis. Four defense-related genes were significantly up-regulated in conchocelis, such as Phlox was up-regulated 166.06±56.52 folds, while the genes of thallus at different growth stages exhibited a slight extent of up-regulation, moreover, the changes of these genes had variation trend at different stages. The composition and contents of volatile substances varied with different growth stages, but the 8-carbon volatiles predominated, such as 2-octenal, 5-octen-1-ol, 2-octen-1-ol and 1-octen-3-ol, etc. By using PCA method, the profiles of volatiles of thallus and conchocelis could be separated clearly, indicating an obvious difference in the profiles of volatiles between them. After being stimulated with agaro-oligosaccharides, some new volatiles in 80 d thallus and conchocelis were generated, and some 8-carbon volatiles were increased significantly. Overall, these results indicated that the different growth stages of P. haitanensis had different response modes to agaro-oligosaccharides, in which conchocelis responded most intensively.

Abstract:In order to popularize the circle hook in Chinese tuna longline fisheries, the mechanical properties of ring hook and circle hook must be understood. The tensile test was conducted by the universal testing machine. The strain and displacement of the ring hook 3.4-4.5 and circle hook 14/0-4.5 during the tensile test were measured by the digital image correlation system. Results showed that:(1) While the tension acted on the circle hook 14/0-4.5 and ring hook 3.4-4.5 was 500N and 800N, the highest strain of circle hook 14/0-4.5 was 0.012 and 0.018, and that of the ring hook 3.4-4.5 was 0.010, and 0.025, respectively;(2) While the tension acted on the circle hook 14/0-4.5 and ring hook 3.4-4.5 was 500N and 800N, the highest displacement of circle hook 14/0-4.5 was 5.16mm and 8.50mm, and that of the ring hook 3.4-4.5 was 4.36mm and 6.01mm, respectively. Results of Chi-square test showed that there were no significant differences in the strain or displacement between circle hook 14/0-4.5 and ring hook 3.4-4.5(P>0.05). Results suggested that the circle hook 14/0-4.5 should be popularized in the Chinese tuna longline fisheries.

Abstract:To explore the effect of KK-42 on the molt cycle of juvenile Macrobrachium nipponense and its possible mechanism, the juvenile prawns(1.2-2.0 cm long) were collected from our aquaculture ground, and acclimated at(26±1)℃ in running-water tanks in the laboratory and fed twice daily for 1 week before the experiments. The prawns were administered with KK-42 at a concentration of 0(control group) or 1.95×10^-4 mol/L(treatment group) for 1 min, respectively. A portion of them were used to measure the growth rate and molt cycle of juvenile prawns; and the rest, being at intermolt stage(C) and premolt stage(D), were used to analyze quantitatively cuticular chitinase1 gene(Mnchi-1) mRNA level and the chitinase activity. The results showed that the average weight of treatment group was significantly higher than that of the control one, and its growth rate increased significantly in the first two weeks after KK-42 treatment. The duration of molting period tended to prolong following the growth of juvenile prawns, and that was shortened by KK-42 treatment at the first two cycles among four consecutively-determined molt cycles, from(8.70±1.07),(9.81±0.43)d/molt cycle to(6.93±0.97),(8.11±1.20)d/molt cycle, respectively. The culticular Mnchi-1 mRNA level as well as the chitinase activity in the stage C increased by more than 10 and 2 times, respectively, at 3, 6 and 9 h after KK-42 treatment, but those in the stage D, only had a modest rise at 12 h. The results display that KK-42 can importantly up-regulate the culticular Mnchi-1 gene expression and chitinase activity in stage C and D, which may result in the old cuticle degradation to be triggered in stage C, suggesting one of the molecular mechanisms of KK-42 of shortening molt cycle and promoting growth effect for juvenile M. nipponense.

Abstract:To elucidate the morphological variation of bighead carp(Aristichthys nobilis) fed by feedstuff, 31 morphological proportional characters for four populations(56 specimens) from four treatments as fertilization(group A), fertilization+ 1/2 feeding(group B), fertilization+ feeding(group C) and feeding(group D) were investigated, using the traditional morphological(one-way analysis of variance, cluster analysis, principal component analysis, and discriminant analysis) and truss network analysis. The four populations of bighead carp differed significantly for 24 morphological proportional characters(e.g., TL/BL, BH/BL, SL/BL), while there were no differences for other characters as HH/BL, HL/BL, 4-6/BL, 5-6/BL between different groups. A cluster analysis indicated that the group B, group C and group D were more similar compared to group A. The principal component analysis yielded seven principal components with a cumulative contribution ratio of 94.6%. The scatter diagram of major principal components also showed group A completely separated from other three groups, while the latter overlapped together. The discriminant functions of the four populations of bighead carp were established based on 6 morphological characters that differed significantly among the populations. The accuracy of discrimination from four populations was 92.7%, 87.5%, 64.3% and 87.5%, respectively, indicating the reliability of discriminant functions. In summary, the morphological characteristics of bighead carp fed feedstuff changed significantly. However, the morphological characters of fish head have not changed, while the trunk from head to the dorsal fin is significantly increased, hence giving an illusion of smaller head. It is the first study to prove the bighead carp fed feedstuff still have the big head features, laying the theoretical foundation for rearing bighead carp with feedstuff.

Abstract:MicroRNAs(miRNAs) are a class of small non-coding RNA molecules that negatively regulate gene expression at the post-transcriptional levels by base pairing with target mRNAs which leads to mRNA cleavage or translational repression in eukaryotes. A large number of studies show that miRNAs play a vital role in physical development, cancer, cell differentiation, proliferation and apoptosis, lipid metabolism. Recently, numerous research findings about miRNAs have been gained in aquatic animals. However, no comprehensive summary has been reported in this aspect so far. This paper reviews the recent research progress of miRNAs in aquatic animals. The results show that miRNAs present diverse biological functions in aquatic animals. The aim of this review is to provide basic references for analysing prospects of further development about miRNAs in aquatic animals.

Abstract:The estuarine tapertail anchovy Coilia nasus is a highly valued fish in the Yangtze River, however, its resources have drastically declined due to anthropogenic impacts, e.g., overfishing, habitat degradation, water pollution. This small anchovy has been recently proposed for listing as a Class Ⅱ protected species by the plan for adjustment on China's List of Wildlife under Special State Protection. The long-jaw(supermaxilla) estuarine tapertail anchovy is believed to be an anadromous ecotype of C. nasus with a length ratio of upperjaw to head>1. Anadromous C. nasus has much higher commercial value than that of another freshwater residen tecotype of this species with a length ratio of upper jaw to head<1. In order to understand the migration characteristics of the long-jaw C. nasus, an electronic probe microanalyzer(EPMA) was applied to analyze the microchemistry patterns of element Sr and Ca in otoliths of ten C. nasus of this ecotype collected form Nanjing section of the Yangtze River in 2009 and 2014. The results of line transect analyses showed that the Sr:Ca ratio(i.e., Sr/Ca×10³) in the otolith of the anchovies could be divided into two patterns: ① Sr/Ca ratio fluctuated between low(<3.0) and high(>3.0) phases in the otolith, suggesting the individuals were typical anadromous ecotype which experienced not only the freshwater, but also the brackish water, even the sea water habitats at different stages in their life history. ② Sr/Ca ratio was consistently at low phase(<3.0) throughout the otolith, indicating that the individuals only experienced freshwater habitat during its whole life history. These evidences were supported by the Sr mapping analyses of EPMA. The results showed, for the first time, that the habitat use of long-jaw grenadier anchovy was much more flexible, and furthermore, freshwater resident individual could even be found in long-jaw grenadier anchovies, although it is traditionally believed that every individual of long-jaw C. nasus in the Yangtze River is diadromous ecotype. Therefore, anadromous and freshwater resident C. nasus cannot be effectively distinguished only by the length ratio of upper jaw to head. However, otolith microchemistry analysis can provide an objective approach to solve successfully this problem of C. nasus fishery management.

Abstract:The Argentine shortfin squid(Illex argentinus) in the southwest Atlantic Ocean is one of the most important economic cephalopod targets. Chinese traditional vessels had a very low yield in 2010 after a good harvest year in 2008. According to the catch data from the Chinese commercial squid jigging vessels and the oceanographic environmental data(Sea surface temperature, SST; Sea surface height, SSH and chlorophyll-a, chl.a) from 2008 to 2010, the potential habitat of I.argentinus in the main fishing season(from January to April) was analyzed, and these results were compared to the actual catch positions. The oceanographic environmental factors were combined to find the reasons of its distribution differences in these three years. Results showed that there was nearly same trend between the change of the potential distribution areas and actual catch positions. The habitat in north and south directions in 2008 and 2009 was large compared to the year of 2010, when the region was mainly south of 45°S. The Jackknife test indicated that the SST was the most important oceanographic environmental factor influencing the distribution of I.argentinus. The findings suggested that the SST isotherms can represent the change of ocean currents which can affect the distribution of the I.argentinus. The 12℃ SST isotherm may be a good indicator to search for the fishing ground. The different fishing stocks in 2010 may have impact on the model results. The SSH contour lines, representing the change of eddies can also affect the distribution of the I.argentinus, while the chl.a can only reflect it indirectly. Consequently we suggested that it's mainly needed to observe the changes of SST and SSH when doing the squid fishing ground searching.