Abstract:A serious disease occurred in cultured white-leg shrimp, Litopenaeus vannamei, in greenhouse pond of mariculture farm in Taizhou, Zhejiang Province, in 2019. The diseased L. vannamei showed corkscrew swimming, anorexia, slow growth, hepatopancreas discoloured, with a mortality rate of more than 80% in 2-3 days. To study the pathogenic mechanism of PvL-1 in L. vannamei, the bacteria were isolated from morbid L. vannamei with typical symptoms by using thiosulfate citrate bile salts sucrose (TCBS) agar, with the light Green colony of 3-7 mm in diameter, luminous in dark and Gram negative rods. PvL-1 was identified as Vibrio campbellii with API20E biochemical bacteria identification, with similarity of 90% to reference strains CAIM249. PvL-1 belonged to the same cluster with V. campbellii CP020076 on phylogenetic analysis for fitZ, with 99.31% similarity to reference strains, and same cluster as V. campbellii EF596552, with 98.89% similarity to gapA. V. campbellii species-specific primers were used for PCR test, with 328 bp band for PvL-1 and negative for V. rotiferianus and V. harveyi. These results indicating that PvL-1 was a member of V. campbellii. PvL-1 can form typical β hemolyisis on sheep blood agar and transparent circle on the milk agar, indicating the existence of hemolytic and extracelllar protease toxin. Acute hepatopanergic necrosis, hemolysin gene, flagellate gene and other virulence genes of PvL-1 were analyzed, indicating that PvL-1 has virulence genes such as AP4, TLH, vcahHly, flaC, mukF, gloB, sodB and esrB. The healthy L. vannamei, infected with V. campbellii PvL-1, died with the similar symptoms to naturally morbid L. vannamei, with LD₅₀ of 2.94×10⁴ CFU/ind. Histopathologic examination showed that PvL-1 challenged L. vannamei hepatopancreas showed tubular epithelial cells massive shed and sloughing, hemocytic infiltration etc., which was similar to the naturally morbid L. vannamei. In summary, the luminescent V. campbellii PvL-1 was isolated, with high pathogenicity, which expanded our cognition of the luminescent V. campbellii of L. vannamei.

Abstract:To investigate the role and molecular mechanism of diploidization of cells during the parthenogenetic development of female gametophyte in Pyropia haitanensis, a cDNA sequence of homologue of mad2 was isolated and its expression profile at different developmental stages of parthenogenesis was characterized. In this study, the cDNA of Ph-mad2 spans 672 bp that encodes a protein of 223 amino acids (aa) with a predicted molecular weight of 23.8 ku. The deduced protein sequence of PhMAD2 has a typical HORMA domain and conservative serine and threonine phosphorylation sites. Phylogenetic analysis revealed that evolutionary status of P. haitanensis was extremely related to the fungi from Phycomycetes, such as Saprolegnia diclina and S. parasitica. Quantitative real-time PCR (qRT-PCR) analysis showed that the expressions of Ph-mad2 at reproductive cell development stage (RDS) and parthenospore development stage (PDS) with diploid carpogonium-like cells and carpospore-like cells were significantly down-regulated compared with that at vegetative cell proliferation stage (VPS) with haploid vegetative cells, while its expression profiles were up-regulated in the later stages of parthenosporophyte formation stage (PFS) and parthenosporophyte growth stage (PGS), in which the diploid carpospore-like germlings and parthenosporophytes underwent normal mitosis. These results suggested that Ph-mad2 reduction potentially prevented the formation of spindle assembly checkpoint (SAC) at mitotic cells during the early stages of parthenogenesis, and triggered their development of diploidization. These results provide important information for revealing the mechanism of spontaneous chromosome doubling in the parthenogenesis of P. haitanensis.

Abstract:China has successively launched fisheries total allowable catches (TACs) pilot programs in 5 costal provinces in 2017-2018. The paper reviewed the progress of the 5 pilots based on surveys study. Some management innovations were made in the pilots: limit access to the pilot fishery by special fishing license, fishing log management, adoption of obersevers, and management involvement of fishers cooperatives. There are similar practices in different pilots regarding criteria for choice of the fish stock for pilot, limit of fishing ground use, vessels and fishing methods, supporting measures, while the following are different: single or multiple species of the target stock, limit access to the fishing ground, quotas allocation, monitoring of the catch landing. Currently there are still challengs for implementation of TACs in China with respect to multiple species fisheries, fishing monitoring system, targeted fish stock survey and monotoring, fishing limit measures, adaptive management capacity and institution structures, and legislation of liability for violation. For further development of the TACs in China, the paper suggests: consummate the legal system of TACs by revising the Fisheries Law of China, enhance fish stock survey and monitoring, develop compositive fisheries data and information system, adopt more limits for fishing operation based on license system, establish inclusive mechanism for public participation and cross-region surveillance, and adopt different models of TAC determination for single species fisheries and multiple species fisheries.

Abstract:In order to investigate the differences of the energy metabolism and growth capacity of Qingbo (Spinibarbus sinensis) with different bogy mass, the resting metabolic rate (RMR) of this kind of fish with different body mass (10, 20, 40, 100 and 180 g groups) was firstly detected. After a 28-day feeding trial, the specific growth rate (SGR), feeding rate (FR) and the feed efficiency (FE) were tested in these groups as well. On the one hand, the RMR of S. sinensis was significantly increased with the increase of body mass, however, the RMR of unit weight was significantly decreased. Meanwhile, both SGR and FR were significantly increased, while the FE was indistinctly affected, and plasma GH hormone content was significantly negatively correlated with body mass (r = −0.753, n = 30). On the other hand, the RMR of unit mass was significantly positively correlated with SGR (r = 0.586, n = 51) and FR (r = 0.640, n = 51,), however insignificantly correlated with FE (r = 0.100, n = 51). The SGR was positively correlated with both FR (r = 0.956, n = 51) and FE (r = 0.447, n = 30), and the relation between FR and FE was not significantly correlated (r = 0.245, n = 30). All the information above suggested that, smaller S. sinensis can keep higher maintenance energy consumption and growth capacity, and this may be due to their higher digestive and assimilating ability.

Abstract:After years of development, China’s fisheries and aquaculture industry has laid a solid economic foundation by successively addressing the difficulties of catching fish, raising fish, and eating fish. The principal contradiction in this area has evolved from the issues surrounding basic livelihood (i.e. food and income) to those concerning habitat conservation, human rights, gender equality, property rights and other high-level needs. Conserving aquatic resources while maintaining fisheries justice have emerged as an irresistible trend of our time, as sustainability and responsibility become increasingly emphasized. Under this premise, fisheries and aquaculture ethics, as a form of superstructure, deserves systematic research for value identification and ranking. The study initially put forward the concept of fisheries and aquaculture ethics, that is, a set of orders and norms dealing with human-fish relations and interpersonal interactions among stakeholders, which take the rationality and legitimacy of fisheries and aquaculture as the research object and provide a judgment basis for relevant practices. Main points regarding ecological, social and industrial ethics in fisheries and aquaculture were summarized, followed by the exploration of ethics-based management theories from eco-holistic perspectives (e.g. Precautionary Principle, Ecosystem-based Management, Large Marine Ecosystems) to value-balanced perspectives (e.g. Management Strategy of Evaluation, Justification Theory). Practical guidance mainly enshrined in Code of Conduct for Responsible Fisheries was then analyzed together with ethical matrix developed for performance evalution, before specific discussion on the ethical dimension in China’s modern fisheries and aquaculture governance. China is the home of the largest number of both fishing vessels and fishermen, and is the only major country where the total output of aquaculture products exceeds that of fishing harvest, making its fisheries and aquaculture management more complicated than that of any other country in the world. Such a scenario requires a unique set of social and ecological ethics tailored for its governance. It is found that China’s traditional ecological wisdom contains rich ethical elements; and there exist ethical challenges in effectively addressing the social problems in China’s Three Fisheries and Aquaculture Issues, namely, the issues concerning the industry, villages and fishermen/aquaculture farmers. China shall further clarify the value scale and ethical foundation of fisheries and aquaculture. The study aims at promoting a sustainable conservation and development outlook in accordance with China’s conditions, in an effort to truly realize the "integration of nature and man" and coordinated development in this sector.

Abstract:The brain structure of Octopus minor was observed by anatomy and paraffin section. The results showed that the brain was divided into three parts according to the location of the esophagus: the supraoesophageal mass, the suboesophageal mass and the optic lobe area on both sides of the supraoesophageal mass and the suboesophageal mass. The supraoesophageal mass includes the vertical lobe, the superior frontal lobe, the inferior frontal lobe, the anterior basal lobes and the posterior basal lobes. The suboesophageal mass includes the brachial lobe, the pedal lobe, the magnocellular lobe, the chromatophore lobe, the visceral lobe, the palliovisceral lobe and the vasomotor lobe. The optic lobe area includes the optic nerve, the optic lobe, the optic gland, the olfactory lobe, the peduncle lobe and the optic tract. Paraffin section, optical microscope and transmission electron microscope were used to observe the microstructure and ultrastructure of the optic gland. The results showed that there was a layer of connective tissue wrapped outside the optic gland, which was located in the optic tract area, adjacent to the olfactory lobe and the peduncle lobe. A large number of secretory cells were observed in the inner part, with a relatively large nucleus and a diameter range of 4-8 μm. The secretory cells were rich in rough endoplasmic reticula, Golgi apparatus, secretory vesicles and vacuoles secreted by Golgi apparatus. The results showed that the structural characteristics of the optic glands of O. minor were similar to those of Sepiella maindroni and O. vulgaris.

Abstract:This study aimed to explore the splenic histology and evolutionary level of Quasipaa spinosa, and also aimed to identify the existence and function of blood–spleen barrier. Histologic technology, transmission electron microscopy, immunohistochemistry, injection of trypan blue, acid phosphatase(ACP) and alkaline phosphatase(AKP) reaction were used in the study. The results showed that spleen without periarterial lymphatic sheaths (PALS) and germinal centres (GC) had two clearly distinguishable areas including the white pulp and the red pulp with fuzzy boundary. In addition to that, there was no evidence for the presence of a marginal zone, and less ellipsoids were located in the boundary region without periellipsoidal lymphatic sheaths (PELS). The white pulp was surrounded by melano-macrophage centres (MMCs) which was formed by numerous melano-macrophages and MMCs were also located in the white pulp occasionally. A few of mast cells existed in the red pulp and close to the vein. The collagen fibers existed in splenic capsule and splenic cord, especially in the wall of arteriole. The result in the detection by Alphα-naphthyl acetate esterase(ANAE) was negative. The dynamic histology of Q. spinosa after injection of trypan blue showed the blue signal was first discovered in free macrophagocyte in the red pulp after one hour post intraperitoneal injection, and then gradually congregated in splenic cord. The blue signal of diffuse distribution in reticular cells in splenic cord was weakened after twenty-four hours post intraperitoneal injection. No trypan blue was detected in the white pulp, ellipsoids and MMCs throughout the whole course of the dynamic study. Meanwhile, the result of dynamic histology post intracardiac injection was similar to that of intraperitoneal injection, except that the positive signal was discovered half an hour earlier. The result of the detection AKP and ACP on the basis of dynamic histology post intraperitoneal injection showed less ACP was detected in normal spleen, but the ACP content in splenic cords and MMCs had a trend of increasing initially and then decreasing afterwards. In contrast, the AKP remained negative in the whole study.

Abstract:Zinc (Zn) is an essential trace element, and maintains the normal growth, development and nutrient metabolism of aquatic animals. To decipher the mechanism of Zn regulating nutrient metabolism in aquatic animals, the present paper summarizes the research progress involved in dietary Zn requirements and the key factors influencing Zn requirements, structures and functions of key genes and proteins (such as ZnTs and ZIPs families, MTs and MTF-1) relevant with Zn homeostatic regulation, and the effects and mechanism of Zn influencing lipid deposition and metabolism. At present, although some progresses have been made in the Zn nutrition, physiology and metabolism of aquatic animals, many underlying problems remain unsolved and further investigations are needed: ① wide-accepted evaluating standards for the optimal dietary Zn requirement; ② the structure and function of key genes and proteins in the regulation of Zn homeostasis, and the revelant mechanism of absorption, transport and homeostasis of Zn in aquatic animals, which provides the basis for the addition of dietary Zn sources; ③ the signal pathways and molecular mechanism of Zn regulating nutrient metabolism, which provides the reference for the precise regulation of zinc nutrition in aquatic animals.

Abstract:Based on samples collected from bottom trawl surveys before the end of summer fishing moratorium in Laizhou Bay from 2010 to 2017, the temporal and spatial distributions of Portunus trituberculatus were studied by silhouette width of clustering, with the released and recaptured data. Some suggestions were made on the resource status of P. trituberculatus in Laizhou bay. The results show that resources of P. trituberculatus in the south are obviously superior to those in the north from the spatial distribution, which can be clustered into near-shore group, far-shore group and deep-sea group by Rousseeuw index. Group assessment is reasonable. The average silhouette width of station clustering was 0.34, the similarity of the stations in the group was higher, and the clustering effect was better; the resources of P. trituberculatus have obvious interannual fluctuation from the temporal distribution, which can be clustered into good group, general group and poor group by Rousseeuw index. Group assessment is reasonable. The average silhouette width of year clustering was 0.15, the year similarity within the group was low, and the clustering effect was poor. In addition, according to Pearson correlation analysis of spatial grouping, we found that the resource status is closely related to the near-shore group, and according to SIMPER analysis of temporal grouping, we found that the resource status mainly depends on the near-shore resources. Therefore, the management and protection of the near-shore group is very important to the resource of P. trituberculatus before the end of summer fishing moratorium in Laizhou Bay. During enhancement and releasing of P. trituberculatus, it is suggested that we should not only maintain the releasing scale, but also focus on the protection and management of resources in the early days, and then effectively increase the near-shore resources and further realize the significance of the enhancement of P. trituberculatus.

Abstract:The coastal waters of Shandong have rich fisheries resources but have suffered from pressures including overfishing. In order to comprehensively understand the composition and structure of the fish community in Shandong coastal waters and to provide a scientific basis for the conservation of fishery resources, a fishery resources survey was conducted in Shandong coastal waters from 2016 to 2017 using bottom trawl in four seasons. A range of multivariate statistical methods including non-metric multi-dimensional scaling (NMDS) and ANOSIM were used to analyze the species composition and spatial heterogeneity of the community structure. The results showed that a total of 134 species were caught in this survey, of which 53 species had Index of relative importance IRI ≥ 1. NMDS analysis showed that the 53 species could be divided into three groups, a, b, c. Among them, Group a was characterized by the large biomass in summer and Group c in autumn. Group b was characterized by the relatively small changes of biomass throughout the year and the obvious dominance in spring and winter. Regarding the spatial structure of fish community, NMDS and ANOSIM showed that the fish community structure in Laizhou Bay (Zone A) was significantly different from that in the northern and southern adjacent waters (Zones B and C) of the Shandong Peninsula, and the differences persisted in all seasons. SIMPER showed that the species that caused the spatial heterogeneity of community structure between Zone A and Zone B & C were Cynoglossus joyneri and Lophius litulon in spring; Engraulis japonicus in summer; Chelidonichthys kumu in autumn; Acanthogobius ommaturus and L. litulon in winter.

Abstract:Microcystis aeruginosa is a kind of cyanobacteria that can bloom in freshwater lakes and slow-flowing water, especially in freshwater aquaculture waters. A large amount of feces will be excreted by benthic fish in the growth process, which may provide conditions for the recovery and increment of M. aeruginosa. To explore the effects and track of the fish intestinal excreta (Mylopharyngodon piceus and Silurus asotus)on the recruitment of dormant M. aeruginosa from the sediment, and to find potential factors and mechanism, simulation experiments on the recruitment of M. aeruginosa cells from sediment were performed in the presence or absence of the fish intestinal excreta. The intestinal excreta of M. piceus or Silurus asotus were fully mixed with cells of dormant M. aeruginosa, and then they were all buried in the lake sediments. The co-culture and recruitment experiments were carried out at the gradient temperatures of 10 ℃, 15 ℃ and 20 ℃. The results showed that the recruitment rate of dormant M. aeruginosa cells in M. piceus excreta group (MP), S. asotus excreta group (SA) and M. piceus or S. asotus excreta mixture group (MP-SA) were all significantly higher than that in the control group (CK) (P < 0.05), and the recruitment rate of dormant M. aeruginosa cells in the MP group was significantly higher than those in the SA group and the MP-SA group. At 20 ℃, the recruitment rate of dormant cells of M. aeruginosa in MP group was significantly higher than that in SA group, MP-SA mixed group and CK group, however, there was no significant difference in the recruitment rate between SA group and CK group (P > 0.05), and there was no significant difference between MP-SA group and CK group. From the point of view of gradient experiment temperature, the recruitment rate of dormant M. aeruginosa cells both in the control group and in the experimental group (excreta group) increased with the increase of temperature. At 10 ℃, recruitment rate of dormant M. aeruginosa cells in the control group, the Mylopharyngodon piceus excreta group (MP), the S. asotus excreta group (SA) and the mixed group (MP-SA) was 14%, 45%, 36% and 28%, respectively, and at 15 ℃, recruitment rate of dormant M. aeruginosa was 43%, 60%, 51%, 50%, respectively, at the experimental temperature of 20 ℃, recruitment rate of dormant M. aeruginosa was 49%, 61%, 52%, 51%, respectively. For the control group and the three experimental groups (excreta group), t recruitment rate of dormant M. aeruginosa at 15 ℃ and 20 ℃ was significantly higher than that at 10 ℃, but there was no significant difference in the recruitment rate of dormant M. aeruginosa cells at 15 ℃ and 20 ℃ (P > 0.05). At the same time, the main recruitment period of dormant M. aeruginosa was from day 3 to day 15. During the experiment at 10 ℃, 15 ℃ and 20 ℃, the dominant bacteria of MP group were mainly Pseudomonas, and the dominant bacteria of SA group and MP-SA group were mainly Bacillus and Firmicute, respectively. In the MP group, at 10 ℃, the dominant bacteria in the sediment were Pseudomonas, Fusobacteria, Bacillus, Vibrio, Proteobacteria and Firmicute, which accounted for 33%, 13%, 9%, 7%, 4% and 4%, respectively, the proportion of dominant bacteria was 70% in total bacteria. They accounted for 61% and 54% at 15 and 20 ℃, respectively. For the S. asotus excreta group (SA), at 10 ℃, 15 ℃ and 20 ℃, the dominant bacteria in the sediment were Bacillus, Bifidobacterium, lactic acid bacteria, Firmicute, Vibrio and Pseudomonas, which accounted for 64%, 50% and 42% of the total bacteria respectively. For MP-SA group, at 10, 15 and 20 ℃, the dominant bacteria in the sediment were bacillus, Bifidobacterium, lactic acid bacteria, Firmicute, Proteobacteria and Pseudomonas, and their proportions in the total bacteria were 50%, 45% and 43%, respectively. The concentration of total bacteria in the sediment of each experimental group increased with the increase of temperature, and the concentration of total bacteria at 15 ℃ and 20 ℃ was significantly higher than that at 10 ℃. 0-12 d was the period of bacterial proliferation. The physical and chemical indexes of the sediment-water interface (SWI) were measured and it was found that the the N/P(DIN∶SRP) ratio of MP group, SA group and MP-SA group were significantly lower than those of the control group during the period of day 3 to day 12. At the three gradient temperatures, in the same period of 0-9 d, the nitrogen-phosphorus ratio decreased the fastest in M. piceus excreta group, followed by S. asotus excreta group, the mixed group and the control group (CK). There was no significant change of nitrogen-phosphorus ratio in the whole process for the control group. In the same period, there were significant differences between the three experimental groups and the control group (P < 0.05), and there were also significant differences among the three experimental groups. During all experiments, the change trend of dissolved oxygen (DO) concentration was basically the same as that of nitrogen-phosphorus ratio, and dissolved oxygen. The results showed that the intestinal excreta of M. piceus or S. asotus could promote the recruitment of dormant M. aeruginosa, which may be the result of the decline of N/P ratio and dissolved oxygen concentration caused by flora in the excreta during the growth and proliferation period, and the effect of promoting-recruitment was more significant in the lower temperature range (10-15 ℃). The results are of theoretical significance for the recruitment of dormant M. aeruginosa cells, clearing the pond of silt, and the mechanism of bloom outbreak of M. aeruginosa in spring. It also provides a new way to prevent and control the bloom of M. aeruginosa in aquaculture waters.

Abstract:The purpose of this study is to establish a numerical model of dynamic energy budget for Sinonovacula constricta. According to DEB theory, the basic parameters of the model were measured and calculated by corresponding methods: shape coefficient δ_m, energy per unit volume of Arrhenius temperature T_A, per unit time [p_M], energy needed to form structural matter per unit volume [E_G] and maximum stored energy per unit volume [E_M]. Taking water temperature and chlorophyll concentration as forced functions, and based on the growth data of S. constricta from different seedling sources and water quality factors in ponds, STELLA 10.0 software was used to establish the DEB model of the system. The results show that the mean value is 0.3458, the average value of TA is (5 448±960) K, [p_M]=17.68 J/(cm³·d), [E_G]=4 050 J/cm³, [E_M]= 1 840 J/cm³; and the constructed DEB model can well simulate the growth of dry weight of the soft body part and reflect the energy distribution at different time. The water temperature of the seedling released in spring was the main growth restriction factor from August 10 to September 20, and the food was the factor from September 30 to November 10. The main limiting factor was that S.constricta released in autumn showed a strong temperature limit from July 1 to September 20, while the food limit ran through the whole simulation period, with the maximum limit from March 10 to May 20. It is inferred that S. constricta released in autumn could increase the supply of food algae in spring and reach the commercial specification before high temperature in summer.

Abstract:The present study aimed to determine the effects of dietary 0.40% chondroitin sulfate (CS) and 0.40% acidolysis oxidated konjac glucomannan (AOKGM) added to feed for 8 weeks on growth, antioxidant indices and tissues (liver, kidney and gill) cadmium accumulation of Schizothorax prenanti. A total of 450 healthy S. prenanti individuals with similar body weight (98.00±8.54) g were randomly assigned to three groups with three replicates per group and 50 fish per replicate. After 8 weeks, the growth and the serum antioxidant indices of S. prenanti were determined. In addition, the cadmium stress test was carried out for 15 days (0, 0.10, 0.25, 1.00 mg/L), and the serum antioxidant indices and tissues cadmium accumulation of fish under cadmium stress were determined. The results were as follows: compared with the control group, specific growth rate (SGR), spleen index (SI) and head kidney index (HKI) were increased when the diets were supplemented with CS and AOKGM. Additionally, the crude lipid, crude protein and ash content of muscles were significantly increased when both polysaccharides were added. Compared with the control group, the serum superoxide dismutase (SOD) activity, total protein (TP) and nitric oxide (NO) content of the fish were significantly increased, and glucose (GLU) content of fish was significantly decreased when diets were supplemented with both polysaccharides. The glutathione peroxidase (GSH-Px) activity and cholesterol (TC) content of fish were significantly increased, and malondialdehyde (MDA) content of fish was significantly decreased when CS was added to the diet. Compared with 0 mg/L cadmium, MDA content was the highest and SOD activity was the lowest at 1.00 mg/L cadmium, GSH-Px activity was significantly decreased and NO content was significantly increased at 0.25 and 1.00 mg/L cadmium. Compared with 0 mg/L cadmium, the SOD activity significantly increased, and MDA content significantly decreased, while NO content significantly decreased at 0.10-1.00 mg/L cadmium when diets were supplemented with both polysaccharides. CS significantly increased GSH-Px activity at 0.10 and 0.25 mg/L cadmium. AOKGM significantly increased GSH-Px activity at 0.25 and 1.00 mg/L cadmium. Compared with 0 mg/L cadmium, the cadmium accumulation in liver, kidney and gill of fish significantly increased at different cadmium concentrations, while CS and AOKGM decreased the cadmium content of tissues. Taken together, the results showed that 0.40% CS and AOKGM had certain effects on the growth and antioxidant capacity of S. prenanti, and it reduced the cadmium accumulation in tissues. This study provides a new theoretical basis for the development of nutritional feed for S. prenanti.

Abstract:There are two twist genes in vertebrates, namely twist1 and twist2, which have a regulatory effect on bone development. To explore the relationship between twist1, 2 and intermuscular bone development in barbel steed (Hemibarbus labeo), cDNAs of the twist1 and twist2 genes of H. labeo were cloned and sequenced. Sequence analysis revealed that H. labeo TWIST1 and TWIST2 were conserved in most of the teleosts, and they all had a helix-loop-helix (HLH) domain and a tryptophan-arginine (WR) domain. Phylogenetic tree analysis indicated that H. labeo twist1 and twist2 were closely related to that of zebrafish (Danio rerio). Expression of twist1 and twist2 transcripts were detected in all the tested tissues. twist1 was the highestly expressed in the brain, followed by the heart, and the lowest in the spleen. twist2 had higher expression levels in skin and gill, and the lowest expression in spleen. The transcript levels of the twist1 and twist2 gene significantly changed during the four developmental stages of intermuscular bone development, suggesting that there is a certain correlation between twist genes and intermuscular bone development. This study, for the first time, cloned the twist genes in economic fish and revealed the correlation between twist genes and intermuscular bone development. The results will provide basic data for further investigation of twist gene function and its regulation role in intermuscular bone development.

Abstract:Synonymous mutation can induce phenotypic variation by altering gene transcription, translation and post-transcription process in recent studies on human disease. To study the effects of synonymous mutation on gene transcription and translation, the total of 12 genotypes (CG, TA, 1T, 2T, 3T, 4A, 5T, 1C, 2C, 3C, 4G and 5G) deduced from the five SNP synonymously mutated loci in MSTN genes of Chinese mitten crab (Eriocheir sinensis) (Es-MSTN), such as SNP1(C/T), SNP2(C/T), SNP3(C/T), SNP4(A/G) and SNP5(T/G), were employed by the means of site-directed mutagenesis, in vitro transcription, and gene overexpression. The results showed that the 12 alleles displayed obviously different transcriptional efficiency in vitro, and the highest transcriptional level was found in the 1C allele and the lowest level in the CG and TA alleles, in which the TA allele exhibited significantly higher transcriptional level than the CG allele. The overexpression in 293T cells found that expression intensity of different mutant genotypes was significantly different at different time (24, 36, 48, 60, 72, 84, 96 and 108 h) after transfection, and the TA allele exhibited significantly higher expression level than the CG allele. Generally, the present study indicated that these five synonymous mutations had important effects on transcription and translation of Es-MSTN gene, suggesting that synonymous mutations could play an important role in biological process. Further studies at post-transcriptional and post-translational levels may shed light on the intrinsic relationship between gene function and phenotypic variation in E. sinensis.