Jiteng Wang

Effect of dietary lipid level on growth performance, feed utilization and body composition by juvenile red spotted grouper (Epinephelus akaara)

This study was designed to determine the effect of dietary lipid level on growth performance, feed utilization and body composition of juvenile red spotted grouper, Epinephelus akaara. Triplicate groups of 12 fish (IBWxa0=xa02.51xa0g) with three isoenergetic and isonitrogenous experimental diets formulated by increasing lipid levels (5.98, 9.11 and 12.57xa0%) were fed to satiety for 8xa0weeks. At the end of the feeding trial, weight gain and specific growth rate were significantly higher for the fish fed diets with 9.11 and 12.57xa0% compared to the treatment which containing 5.98xa0% dietary lipid levels. With the increase of dietary lipid levels, feed conversion ratio decreased but protein efficiency ratio increased. As dietary lipid level increased, viscerosomatic index and intraperitoneal fat ratio increased dramatically, while no significant difference in hepatosomatic index was found in this experiment. In conclusion, under the experimental conditions, the increase of dietary lipid level beyond 9.11xa0% had no further beneficial effects.

Ovarian Transcriptome Analysis of Portunus trituberculatus Provides Insights into Genes Expressed during Phase III and IV Development

Enhancing the production of aquatic animals is crucial for fishery management and aquaculture applications. Ovaries are specialized tissues that play critical roles in producing oocytes and hormones. Significant biochemical changes take place during the sexual maturation of Portunus trituberculatus, but the genetics of this process has not been extensively studied. Transcriptome sequencing can be used to determine gene expression changes within specific periods. In the current study, we used transcriptome sequencing to produce a comprehensive transcript dataset for the ovarian development of P. trituberculatus. Approximately 100 million sequencing reads were generated, and 126,075 transcripts were assembled. Functional annotation of the obtained transcripts revealed important pathways in ovarian development, such as those involving the vitellogenin gene. Also, we performed deep sequencing of ovaries in phases III and IV of sexual maturation in P. trituberculatus. Differential analysis of gene expression identified 506 significantly differentially expressed genes, which belong to 20 pathway, transporters, development, transcription factors, metabolism of other amino acids, carbohydrate and lipid, solute carrier family members, and enzymes. Taken together, our study provides the first comprehensive transcriptomic resource for P. trituberculatus ovaries, which will strengthen understanding of the molecular mechanisms underlying the sexual maturation process and advance molecular nutritional studies of P. trituberculatus.

Effects of different dietary lipid sources on growth performance and tissue fatty acid composition of juvenile swimming crab Portunus trituberculatus

This study was conducted to evaluate the effects of dietary lipid sources on the growth performance and fatty acid composition of the swimming crab, Portunus trituberculatus. Four isonitrogenous and isoenergetic experimental diets were formulated to contain four separate lipid sources, including fish, soybean, rapeseed, and linseed oils (FO, SO, RO, and LO, respectively). With three replicates of 18 crabs each for each diet, crabs (initial body weight, 17.00±0.09 g) were fed twice daily for 8 weeks. There were no significant differences among these groups in terms of weight gain, specific growth rate, and hepatosomatic index. However, the RO groups’ survival rate was significantly lower than FO groups. The feed conversion and protein efficiency ratios of RO groups were poorer than other groups. The proximate compositions of whole body and hepatopancreas were significantly affected by these dietary treatments. Tissue fatty acid composition mainly reflected dietary fatty acid compositions. Crabs fed FO diets exhibited significantly higher arachidonic, eicosapentaenoic, and docosahexaenoic acid contents in muscle and hepatopancreas compared with VO crabs. Linoleic, oleic, and linolenic acids in muscle and hepatopancreas were the highest in the SO, RO, and LO groups, respectively. The present study suggested that SO and LO could substitute for FO in fishmeal-based diets for swimming crabs, without affecting growth performance and survival.

Transcriptome analysis reveals carbohydrate-mediated liver immune responses in Epinephelus akaara

As the cheapest energy source, carbohydrates are used in fish feeds to improve physical quality and reduce catabolism of proteins and lipids. The liver is the primary organ for metabolism and is also an important site of immune regulation. Here, we investigated the effect of different dietary carbohydrate levels on growth and health by evaluating the liver transcriptome of Epinephelus akaara. In this study, E. akaara juveniles were fed diets containing few (0% corn starch), moderate (18% corn starch), and high (30% corn starch) levels of dietary carbohydrate. After an 8-week feeding trial, E. akaara fed 30% dietary carbohydrates exhibited poor growth performance compared with those fed 0% and 18% dietary carbohydrates (Pu2009>u20090.05). Genes related to the immune system, including IL8, TLR9, CXCR4, CCL4, and NFκB inhibitor alpha, were over-expressed in E. akaara fed the highest level of carbohydrate (30%). This general over-expression could indicate activation of inflammatory processes in the liver. The liver transcriptome data of E. akaara reported here indicate that high carbohydrate level of diet can lead to poor growth and inflammatory immune response in E. akaara.