Transcriptome-Based Analysis of the Effects of Salt Stress on the Embryos of Hypomesus nipponensis

Abstract

Simple Summary Climate change and human activities are increasing the salinity of many inland waters, which poses a threat to fish reproduction. The pond smelt (Hypomesus nipponensis) is a fish that naturally inhabits brackish water, making it a valuable model for studying how fish cope with salt stress. In this study, we exposed pond smelt embryos to four salinity levels, ranging from freshwater to 21 parts per thousand (‰), for seven days and examined the resulting changes in their gene activity. We found that the embryos could tolerate up to 21‰ salinity, although their hatching success decreased at higher salinities. Salt stress caused thousands of genes to alter their activity. At moderate salinities, more genes were downregulated than upregulated, but at the highest salinity, the number of upregulated genes increased. Our results provide a molecular basis for evaluating the potential of this fish for aquaculture in saline or alkaline waters, which could aid in utilizing vast, currently unused, saline water resources.