Hepatic triacylglycerol secretion , lipid transport and tissue lipid uptake in blunt snout bream ( Megalobrama amblycephala ) fed high - fat diet

Research advances in the genomics and applications for molecular breeding of aquaculture animals

Blunt snout bream (Megalobrama amblycephala) are susceptible to hepatic steatosis when maintained in modern intensive culture systems. The aim of this study was to investigate the potential roles of microRNAs (miRNAs) in diet-induced hepatic steatosis in this species. MiRNAs, small non-coding RNAs that regulate gene expression at the posttranscriptional level, are involved in diverse biological processes, including lipid metabolism. Deep sequencing of hepatic small RNA libraries from blunt snout bream fed normal-fat and high-fat diets identified 202 (193 known and 9 novel) miRNAs, of which 12 were differentially expressed between the normal-fat and high-fat diet groups. Quantitative stem-loop reverse transcriptase-polymerase chain reaction analyses confirmed the upregulation of miR-30c and miR-30e-3p and the downregulation of miR-145 and miR-15a-5p in high-fat diet-fed fish. Bioinformatics tools were used to predict the targets of these verified miRNAs and to explore potential downstream gene ontology biological process categories and Kyoto Encyclopedia of Genes and Genomes pathways. Six putative lipid metabolism-related target genes (fetuin-B, Cyp7a1, NADH dehydrogenase (ubiquinone) 1 beta subcomplex subunit 2, 3-oxoacid CoA transferase 1b, stearoyl-CoA desaturase, and fatty-acid synthase) were identified as having potential important roles in the development of diet-induced hepatic steatosis in blunt snout bream. The results presented here are a foundation for future studies of miRNA-controlled lipid metabolism regulatory networks in blunt snout bream.

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The effect of exposure to a high-fat diet on microRNA expression in the liver of blunt snout bream (Megalobrama amblycephala)

We have sequenced the genome of the largest freshwater fish species of the world, the arapaima. Analysis of gene family dynamics and signatures of positive selection identified genes involved in the specific adaptations and unique features of this iconic species, in particular it’s large size and fast growth. Genome sequences from both sexes combined with RAD-tag analyses from other males and females led to the isolation of male-specific scaffolds and supports an XY sex determination system in arapaima. Whole transcriptome sequencing showed that the product of the gland-like secretory organ on the head surface of males and females may not only provide nutritional fluid for sex-unbiased parental care, but that the organ itself has a more specific function in males, which engage more in parental care.

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The genome of the arapaima (Arapaima gigas) provides insights into gigantism, fast growth and chromosomal sex determination system.

Molecular cloning, characterization and expression analysis of PPAR gamma in the orange-spotted grouper (Epinephelus coioides) after the Vibrio alginolyticus challenge.

The blunt snout bream Megalobrama amblycephala is the economically most important cyprinid fish species As an herbivore, it can be grown by eco-friendly and resource-conserving aquaculture However, the large number of intermuscular bones in the trunk musculature is adverse to fish meat processing and consumption As a first towards optimizing this aquatic livestock, we present a 1116-Gb draft genome of M amblycephala, with 77954 Mb anchored on 24 linkage groups Integrating spatiotemporal transcriptome analyses, we show that intermuscular bone is formed in the more basal teleosts by intramembranous ossification and may be involved in muscle contractibility and coordinating cellular events Comparative analysis revealed that olfactory receptor genes, especially of the beta type, underwent an extensive expansion in herbivorous cyprinids, whereas the gene for the umami receptor T1R1 was specifically lost in M amblycephala The composition of gut microflora, which contributes to the herbivorous adaptation of M amblycephala, was found to be similar to that of other herbivores As a valuable resource for the improvement of M amblycephala livestock, the draft genome sequence offers new insights into the development of intermuscular bone and herbivorous adaptation

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The draft genome of blunt snout bream (Megalobrama amblycephala) reveals the development of intermuscular bone and adaptation to herbivorous diet.

PPARγ, an important gene related to lipid metabolism and immunity in Megalobrama amblycephala: cloning, characterization and transcription analysis by GeNorm.

Hybrid vigor among three geographical populations of Megalobrama amblycephala, including Liangzi Lake population (L), Poyang Lake population (P) and Yuni Lake population (Y), was predicted by combination ability and SSR markers. The first generation individuals of 9 complete diallel cross combina-tions of three populations were measured with total length and body weight. The analysis of combination ability showed that the sire of Yuni population had the largest general combining ability effective value; however, the largest general combining of total length in dam was Poyang population, while that of body weight was Liangzi population. There were high effective combinations among P♂×P♀, L♂×Y♀ and Y♂×Y♀ which had high specific combining ability, so these combinations were suitable as basic selective popula-tions. The results obtained from SSR markers showed that all three populations had high genetic heteroge-neity (He, 0.877-0.863), polymorphism information content (PIC, 0.848-0.820) and marker index (MI, 8.959-11.242). Among the three populations, Liangzi population and Yuni population revealed the largest genetic distance, reaching 0.336 2. According to the result, L♂×Y♀ would have the highest hybrid vigor among those combinations.

Xueqiao Qian

Papers

The draft genome of blunt snout bream (Megalobrama amblycephala) reveals the development of intermuscular bone and adaptation to herbivorous diet.

PPARγ, an important gene related to lipid metabolism and immunity in Megalobrama amblycephala: cloning, characterization and transcription analysis by GeNorm.

Prediction of hybrid vigor among three geographical populations of Megalobrama amblycephala by combination ability and SSR markers