Effect of Heat Starvation Stress on Physiological Immunity and Metabolism of Mizuhopecten yessoensis

Abstract

Mizuhopecten yessoensis is an economical maricultural bivalve mollusk in China and Japan. Due to the high mortality rate, academics have paid more attention to the effects of the environment recently. However, little is known about the physiological, immune, and metabolic effects of M. yessoensis under starvation stress at high temperatures. Herein, transcriptomic libraries of hemolymph and striated adductor muscle from feeding and starved M. yessoensis were constructed. The results showed that the immune indexes decreased in the concentration of M. yessoensis blood cells and liver lysozyme activity at 15 d, M. yessoensis fertility and liver ACP at 30 d of starvation stress, and T-AOC and BCA at 45 d of starvation stress. A total of 853.85 M clean reads were obtained from 20 libraries, with an average total mapping ratio of 83.38% to the reference genome. Based on an examination of the genes that differ in expression between the fasted and feeding groups, 27 up- and 41 down-regulated DEGs were identified in hemolymph, while the numbers in striated adductor muscle were 426 up- and 255 down-regulated. Determined by GO annotation and KEGG pathway mapping, annotations and categories of the DEGs presented diverse biological functions and processes. KEGG analysis showed that most downregulated DEGs in striated muscle were enriched in the pathways involved in metabolism. Genes encoding the enzymes, including eno, pgk, gapA, tpiA, fbp, pgi, and pgm in the gluconeogenesis pathway, were down-regulated, which was indicative of the negative effect of long-term starvation on gluconeogenesis. The down-regulation of PGD and tktA genes in the pentose phosphate pathway suggested that the carbohydrate decomposition and utilization were decreased in starved scallops. Together, the findings demonstrated the influences of food deprivation on carbohydrate metabolism and other processes in M. yessoensis. These results provide foundational information for further understanding of metabolism, especially carbohydrate metabolism of scallops under starvation, which may potentially benefit healthy aquaculture.