| The vertebrate sex determination was generally be divided into genetic sex determination(GSD)and environmental sex determination(ESD).In relatively low vertebrates,the sex determination can be affected by the environmental factors.In general,temperature is a major factor which is regulate the sex determination of ESD species.Many previous studies have reported the effect of temperature on sex determination.However,the mechanism of how ESD species respond to temperature was largely unknow.The Chinese tongue sole(Cynoglossus semilaevis)belongs to Pleuronectiformes,and that was an important marine economic fish in China.There are obvious sex dimorphisms in the growth characteristics and the growth rate of females is 2-4 times than males.Previous research was found that the sex chromosome system of Chinese tongue sole is ZZ/ZW,and the sex determination can be effect by both GSD and ESD.In cultured stocks,about 14% of ZW genetic females reverse to phenotypic males.At the critical period of sex differentiation,the females with genotype ZW can induce the reverse on to pseudomale at high temperature(28 ?).The sex reversal of Chinese tongue sole results in a reduction in output and will have a great impact on the large-scale development of aquaculture.Environmental factors are known to affect sex ratio in vertebrate.Many studies have investigated the mechanism of temperature-dependent sex determination in fish species.However,the upstream temperature-sensitive elements yet to be discovered.To access the effect of heat stress on marine fish,the Chinese tongue sole(Cynoglossus semilaevis)was used as model.Gonadal transcriptome analysis was conducted on females,pseudomales,and males exposed to acute heat stress(28 ?)and normal temperature(22 ?).The differentially expressed gene(DEG)analysis revealed different performance of sexes response to heat stress.The comparison of HS?F and CT?F showed 7267 DEGs,with 405 up-regulated and 6862 down-regulated genes.When comparing HS?P and CT?P,2687 DEGs were identified,of which 1111 were up-regulated and 1576 were down-regulated.In the comparison between HS?M and CT?M,3702 DEGs were identified,of which 424 were up-regulated and 3278 were downregulated.To detect different responses of sexes encounter heat stress,DEGs specific in females,pseudomales,and males were analyzed.Females exhibited 4,565 DEGs,which possessed the most amount in all the three sexes.Pseudomales had 790 DEGs,and males had 1,117 DEGs under heat stress.There were 100,55,and 85 GO terms significantly enriched in females,pseudomales,and males,respectively(p < 0.05),and subsequently there was 103,6,and 12 KEGG pathways significantly enriched in females,pseudomales,and males,respectively(p<0.05).The 1,048 DEGs shared in female,pesudomale,and 26 KEGG pathways were significantly enriched(p < 0.05).In addition,heat shock protein(hsp)gene family,cortisol synthesis and metabolism,and epigenetic regulation were found participated in heat response in gonad,and some of the members performed a sex biased characteristic.The above research results analyzed the gene expression patterns of different sexes of fish after short-term high temperature stress,which laid the foundation for revealing the mechanism of fish's response to temperature and then remodeling sex.Previous studies have shown that cortisol plays an important role in feedback of environmental stress in fish and the hsd11b1 l and hsd11b2 can regulate the concentration of cortisol.In this study,we cloned the full-length c DNA ofhsd11b1 l and hsd11b2 and analyzed their sequence characteristics in Chinese tongue sole.Then,we detected their spatiotemporal expression characteristics and expression patterns after temperature stress conditions.The full-length c DNA of hsd11b1 l was 1650 bp long with 864 bp open reading frame encoding a predicted 287 amino acid protein.While the fulllength of hsd11b2 was 4526 bp longs with 1209 bp open reading frame encoding 402 amino acid protein.q PCR shows that the hsd11b1 l was highest expressed in liver and the expression level in ovary was two-fold than in testis.In particularly,the expression level of hsd11b1 l in ovary was higher than in testis at the stages of 6 mph and 3 yph.The hsd11b2 was expressed mainly in testis and its expression level was reached to a peak in testis at 6 mph;Conversely,its expression was hardly detected in the stages of ovary development.In addition,we analyzed the expression patterns of hsd11b1 l and hsd11b2 after high-temperature(28 °C)treatment.The expression levels of hsd11b1 l and hsd11b2 was significantly reduced in the gonads of male(p<0.05)after the hightemperature treatment for two months.For the acute high-temperature treatment(48h),the expression of hsd11b1 l was significantly decreased in the gonads both of female and male(p<0.05),and the expression of hsd11b2 was significantly down-regulated only in the testis of male(p<0.05).In this study,the results of the expression patterns of hsd11b1 l and hsd11b2 genes in the developmental stages of gonads and the high temperature treatment lays a foundation for understanding the relationship between temperature and sexual differentiation in Chinese tongue sole. |
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