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Captive breeding has been explored in Chinese sturgeon (Acipenser sinensis) for species protection. However, gonad development from stage II to IV of cultured female broodstocks is a handicap. This study aimed to explore the physiological and metabolic changes during the ovary development from stage II to IV of female Chinese sturgeon and the related energy regulatory mechanism, which may be helpful to address the developmental obstacle. The results showed that the oocyte volume increased and the muscle lipid content decreased with the ovary development. Ovarian RNA levels of most genes related to lipid and amino acid metabolism were higher in stage II and III than in stage IV. Serum contents of differential metabolites in arginine, cysteine, methionine, purine, tyrosine, lysine, valine, leucine and isoleucine metabolism pathways peaked at stage III, while the contents of sarcosine, alanine and histidine, as well as most oxylipins derived from fatty acids peaked at stage IV. These results indicated the more active amino acids, lipid metabolism, and energy dynamics of fish body in response to the high energy input of ovary developing from stage II to III, and the importance of alanine, histidine, taurine, folate and oxylipins for fish with ovary at stage IV. [ABSTRACT FROM AUTHOR]

Ovary development of Chinese sturgeon (Acipenser sinensis) in controlled breeding has been reported to respond to dietary lipid levels. However, the corresponding molecular regulatory mechanism about ovary development of Chinese sturgeon is still unclear. To elucidate the molecular mechanism of vitellogenic deposition and hydrolysis, six key genes, namely, vtgr (vitellogenin receptor), atp6v1c1 (Vacuolar H+-ATPase subunit c1) , atp6v1h (Vacuolar H+-ATPase subunit h), ctsb (cathepsin B), ctsd (cathepsin D) and ctsl (cathepsin L) involved in vitellogenic deposition and hydrolysis of Chinese sturgeon were cloned and characterized, and their spatio-temporal mRNA expression profiles as well as transcriptional responses to dietary lipid level were investigated. The full-length cDNA sequences of these six genes showed similar domain structure to their respective orthologous genes from other vertebrates. Tissue-specific expression patterns of these genes were observed in ovary, liver, muscle, spleen, brain, gill, intestine, heart, stomach and kidney. Ovarian expression level of vtgr was the highest in stage II, and ctsl expression was the highest in stage IV, while the mRNA expressions of other 4 genes were the highest in stage III. The increase of dietary lipid level promoted ovary development and elevated the expressions of vtgr, atp6v1c1, atp6v1h, ctsb and ctsd in the ovary. The results of the present study indicated that these genes are crucial for vitellogenic deposition, and provided a preliminary understanding on the molecular regulation of vitellogenic deposition and hydrolysis during ovary development of Chinese sturgeon. • Six ovary development related key genes were cloned in female A. sinensis. • A molecular regulating pathway on vitellogenin proteolysis in oocyte was proposed. • Optimal dietary lipid level increased the mRNA expressions involved in the pathway.. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the energy sources and utilization patterns during embryonic development of Chinese sturgeon through analyzing the biochemical components of embryos at different development stages, and to explore the physiological characteristics and related molecular mechanism during embryogenesis in combination with an embryonic transcriptome analysis. Chinese sturgeon embryo samples were collected at different development stages (fertilized eggs, neurula stage, and tail touching head stage). The results showed that embryonic development was a process of continuous energy consumption. The change of total protein content was consistent with total amino acid content, showing a trend of increasing first and then decreasing. However, the total lipid content decreased significantly during early embryonic development. As for amino acid profile, leucine, arginine and lysine contents showed the highest level within essential amino acids (EAA), while glutamic acid, alanine, aspartic acid and serine contents showed the highest level within non-essential amino acids (NEAA). In terms of fatty acid content, the main quantitative fatty acids were C16:0 in saturated fatty acids (SFA), C18:1 in monounsaturated fatty acids (MUFA), and C22:6n-3 (DHA), C18:2n-6 as well as C20:5n-3 (EPA) in polyunsaturated fatty acids (PUFA). The content of C20:4n-6 (ARA), EPA and DHA were increased at neurula stage compared to fertilized eggs, which indicated their important roles in the structural composition during embryogenesis. Notably, Chinese sturgeon may have the ability to elongate n-3 PUFA to partially meet its requirements for highly unsaturated fatty acids (HUFA) during embryonic development. Transcriptome analysis showed that 19,078 and 6326 differential expressed genes (DEGs) were up-regulated and down-regulated respectively from fertilized eggs to neurula stage; while 3556 and 3150 DEGs were up-regulated and down-regulated respectively from neurula stage to tail touching head stage. KEGG enrichment analysis showed that the protein processing pathway was significantly enriched in early embryonic development through the up-regulated genes of imp4 , pwp2 , utp21 , nop10 , rpl10 _ 17 _ 35 and rps25 ; while the down-regulated genes of ccne1 , ccna2 , ccnb1 , cdk1 _ 2 and plk1 were associated with cell proliferation and differentiation pathway. In late embryonic development, the pathways related to aerobic metabolism, amino acid metabolism and lipid metabolism were significantly enriched through the up-regulated genes of mdh1 , fumc , idh2 , elovl6 and dgat2 ; and the neuroactive ligand-receptor interaction pathway was significantly down-regulated. In general, this study revealed the continuous energy consumption during embryonic development of Chinese sturgeon with specific energy substrates at different stages, and highlighted the DEGs and related pathway involved in the ontogeny and nutrient metabolism, which emphasizes the essentiality of high quality egg production for the success of captive breeding of Chinese sturgeon and would guide the broodstock nutrition for high quality egg production. • The nutritional changes of developing embryos in Chinese sturgeon were revealed. • The embryonic development of Chinese sturgeon is an energy consuming process. • Earlier embryo development is characterized by cell division and lipid energy. • Later embryo relates to organ differentiation, metabolism and protein energy. [ABSTRACT FROM AUTHOR]

A one-year feeding trial was conducted to determine the effects of dietary lipid level on gonad development and steroidogenesis-related gene expressions of Chinese sturgeon ( Acipenser sinensis ). Three isonitrogenous experimental diets (L10, L14 and L18) were compounded with different lipid levels. Results of the feeding trial showed that 2 female Chinese sturgeons in L18 group had developed the ovary to stage III. Chi-square independence test indicated that ovary development was significantly affected by dietary lipid level ( P  < .05). Po and d values of ovary also increased with dietary lipid level. Serum estradiol (E 2 ) and testosterone (T) of L14 group was significantly higher than those in the other two groups ( P  < .05). Blood urea nitrogen (BUN) content decreased as dietary lipid level increased, while triglyceride (TG) and glucose (GLU) contents increased with dietary lipid level ( P  < .05). Vitellogenin receptor ( vtgr ) mRNA expression increased with dietary lipid level ( P  < .05); Gene expressions of androgen receptor ( ar ), cytochrome p 450 17A1 ( cyp17a1 ), steroidogenic acute regulatory protein ( star ), follicle stimulating hormone receptor ( fshr ), luteinizing hormone receptor ( lhr ) and cytochrome p 450 aromatase ( cyp19a1 ) were significantly higher in L14 group than in other groups ( P  < .05), whereas mRNA expression of leptin receptor ( lepr) and DNA-binding protein inhibitor ID-1 ( dbi ) in L14 group were significantly lower ( P  < .05). Based on the gonad development, higher dietary lipid level (16.31%) would promote ovary development of Chinese sturgeon broodstocks through the elevation of vtgr expression to increase the assimilation of vitellogenin in ovary. [ABSTRACT FROM AUTHOR]