The Effect of High Temperature at the Larval Stage on Sex Ratio and Development of Chinese Shrimp (Fenneropenaeus chinensis).

In recent years, extreme weather conditions, such as high temperatures, frequently occur owing to increases in human activities. Fenneropenaeus chinensis is a commercially cultured shrimp with females exhibiting relatively high growth performance. In this study, we investigated the effects of high temperature at the larval stage on the development and sex differentiation of F. chinensis. High-temperature stress increased the female ratio, shortened the developmental time, and decreased the survival rate at each stage. However, genetic sex identification indicated that sex reversal had not occurred. Under high-temperature stress, females showed a relatively highly positive response pattern in gene expression, and responded to this stress by upregulating genes in multiple pathways, particularly for tissue repair. Differentially expressed genes between the high-temperature and control groups at each larval developmental stage were mainly involved in constructing cuticle proteins. Therefore, high temperatures might accelerate the larval development process, resulting in changes in the expression of genes related to epidermal growth, because larval development of Penaeus shrimp is accompanied by a continuous molting process. Simultaneously, high temperatures also caused injury to the body. Because females showed a comparatively positive response pattern of gene expression, they must have comparatively high tolerance to high temperatures. Comparatively serious body injury in male shrimp resulted in a high mortality rate, eventually leading to an imbalance in sex ratio. This research revealed the molecular mechanisms of sex ratio imbalance under the effects of high-temperature stress during the larval stage of F. chinensis, and provides a reference for shrimp farming in the context of global warming.