Abstract

Normally, fish will decrease food intake or even stop feeding during the winter. In previous studies, two widely cultured gibel carp strains (strain A and strain F) showed differences in lipid and glucose metabolism. Therefore, we hypothesized that the physiological changes during the overwintering period would be different between the two strains. Thus, the two strains were starved for 77 days, after which the levels of glucose and lipid metabolism, ER stress, autophagy, and apoptosis were determined. The starvation increased hepatic glycogenolysis and fatty acid β-oxidation but suppressed lipogenesis in both strains overwintering. Considering the effects of genotype, strain F had higher levels of ER stress and autophagy but lower levels of apoptosis than strain A, suggesting that strain F might be more resistant to overwintering starvation. The interactions between strains and starvation periods were observed in plasma triglyceride contents and the mRNA levels of pyruvate kinase (pk), sterol regulatory element binding protein 1 (srebp1), activating transcription factor 4 (atf4), and autophagy protein 12 (atg12). In conclusion, long-term starvation during winter could induce hepatic glycogenolysis and fatty acid β-oxidation but suppress lipogenesis, ER stress, autophagy, and apoptosis in gibel carp, and strain F may be more resistant to starvation during winter. Taken together, these results discovered the responses to prolonged starvation stress during winter in two strains of gibel carp and could provide information for genotype selection, especially for selecting strains better adapted to winter.

Highlights

  • The fish breeding programs can improve economic efficiency through selection usually based on the growth performances of fish [1]

  • A significant decrease in the mRNA levels of pyruvate kinase was only found in strain F (P < 0.05), while in strain A, expression levels of pk were only increased at P2 (P < 0.05)

  • No changes were detected in mRNA levels of glucose-6phosphatase (g6pase) irrespective of strains or time points (P > 0.05)

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Summary

Introduction

The fish breeding programs can improve economic efficiency through selection usually based on the growth performances of fish [1]. Temperature is an important environmental factor that strongly affects growth, general behavior, reproductive performance, and immune responses of animals [2]. Overwintering fish may face stress from both starvation and cold. The physiological responses to overwintering in different strains of fish are remain unclear. Chronic mortality of overwintering fish may be caused by disturbed physiology [11], and this has led to huge economic losses in aquaculture [12]. It is vital to investigate the physiological response to cold stress in fasting farmed fish especially in different strains of fish during winter

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