RNA interference reveals chloride channel 7 gene helps short-term hypersalinity stress resistance in Hong Kong oyster Crassostrea hongkongensis

The chloride channel 7 gene(CLC 7)of the Hong Kong oyster Crassostrea hongkongensis was cloned and named ChCLC 7.The cDNA was 2572 bp in length,with a 5′non-coding region containing 25 bp,a 3′non-coding region containing 327 bp,and an open reading frame of 2298 bp.ChCLC 7 has 96.8%and 92.1%homology with CLC 7 of Crassostrea gigas and Crassostrea virginica,respectively,and it was clustered with CLC 7 of C.gigas and C.virginica.QRT-PCR showed that ChCLC 7 was expressed in all eight tissues,with the highest in adductor muscle and second in gill.The ChCLC 7 expression pattern in gill was altered significantly under high salinity stress with an overall upward and then downward trend.After RNA interference,the expression of ChCLC 7 and survival rate of oyster under high salinity stress was reduced significantly,and so did the concentration of hemolymph chloride ion in 48-96 h after RNA interference.We believed that ChCLC 7 could play an important role in osmoregulation of C.hongkongensis by regulating Cl^(-)transport.This study provided data for the analysis of molecular mechanism against oyster salinity stress.

Gonadal transcriptomic analysis and differentially expressed genes between the testes and ovaries in Trachinotus ovatus

The Trachinotus ovatus is a popular aquaculture species in China.There are no obvious morphological differences between male and female fish,even during maturity,prompting research studies on sex-related features of this fish.To examine sex determination-and gonadal development-related genes,we conducted transcriptome analysis of the ovaries and testes of T.ovatus.A total of 345,972,132 high-quality clean reads were obtained from 12 libraries.In addition,28,137 gonad-expressed unigenes were obtained by mapping the clean reads to the T.ovatus reference genome.A total of 8,237 differentially expressed genes(DEGs)were identified between stage I ovaries and testes,including 3,235 testicular upregulated and 5,002 ovarian upregulated genes.Furthermore,13,448 DEGs were obtained between stage III ovarian and testicular libraries,including 7,576 testicular upregulated and 5,872 ovarian upregulated genes.The DEGs included some sex-determining genes such as sry,dmrt1,and amh.DEGs between ovarian and testicular libraries were significantly enriched with KEGG pathways that are involved in gonadal development,sex determination,and gonadal function.Then,10 DEGs(seven testicular upregulated and three ovarian upregulated unigenes)were selected for quantitative real-time PCR analysis.Four genes(zinc-binding protein A33-like,pro-opiomelanocortin-like,leucine-rich repeat and transmembrane domain-containing protein 2-like,and forkhead boxC1)showed a specific testicular expression pattern.The gonadally expressed as well as testicular and ovarian DEGs provide useful information for further research on the reproductive biology of T.ovatus.