Abstract
Glycogen content is a quantitative trait, its phenotype differences are found between individual oysters due to genetic effects and environmental factors which were including food, water temperature, salinity, and so on. In this study, a full sibling family of Pacific oyster Crassostrea gigas showed different phenotypes with high and low glycogen content between South Huanghai Sea (Rizhao offshore area, RZ) and North Huanghai Sea (Kongtong Dao area, KTD), respectively. At the same time, the content of 11 glucogenic amino acids and 13 fatty acids were also significant differences between RZ and KTD. RNA-seq and small RNA-seq technologies were used for transcriptome sequencing and functional enrichment analysis of differentially expressed RNA were used by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. A total of 2,084 mRNAs, 1,080 long non-coding RNAs (lncRNAs), 34 circular RNAs (circRNAs), and 7 microRNAs (miRNAs) were differentially expressed. Based on these differentially expressed genes (DEGs), miRNA target interactions (lncRNA/circRNA–miRNA pairs and miRNA–mRNA pairs) were predicted using the miRanda software. The differentially expressed mRNAs in this network were mainly shown to be involved in calcium signaling pathway and insulin signaling pathway. These findings could help to speculate that environmental factors may be epigenetically regulated by non-coding RNA in C. gigas, thereby further affecting glycogen content.
Highlights
MATERIALS AND METHODSPacific oyster (Crassostrea gigas) has the characteristics of strong adaptability to the external environment, fast growth, high yield, rich nutrition, and delicious flavor
Previous studies have found that on the one hand, the content of glycogen metabolism-related enzymes directly affects the changes in glycogen content (Hata et al, 1993), on the other hand, the metabolic level of amino acids and fatty acids affects glycogen metabolism (Randle et al, 1963; Fromentin et al, 2011)
The results showed that differentially expressed genes (DEGs) were significantly enriched in 13 pathways, such as calcium signaling pathway, ECM–receptor interaction, and insulin signaling pathway, among which 29 genes were enriched into the calcium signaling pathway, and 17 genes were enriched into the insulin signaling pathway (Figure 2B)
Summary
Pacific oyster (Crassostrea gigas) has the characteristics of strong adaptability to the external environment, fast growth, high yield, rich nutrition, and delicious flavor. It is widely cultivated worldwide as a high-economic value aquatic product. Glycogen content accounts for 20– 40% of the dry weight of oysters, which directly affects the taste of oysters and is an important quality trait. Previous studies have found that on the one hand, the content of glycogen metabolism-related enzymes directly affects the changes in glycogen content (Hata et al, 1993), on the other hand, the metabolic level of amino acids and fatty acids affects glycogen metabolism (Randle et al, 1963; Fromentin et al, 2011). High amino acid content might increase glycogen content, because some amino acids could guide glycogen synthesis (Li et al, 2017b)
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