Abstract
ABSTRACT Temperature influences fish’s susceptibility to infectious disease through an immune response. However, the mechanism underlying this regulation is yet to be elucidated. In this study, we compared the susceptibility of crucian carp that were grown at 18°C and 33°C, respectively, to Aeromonas sobrial infection and found that crucian carp was more susceptible when grown at 33°C. These distinct susceptibilities of fish at different temperatures to infection may partially be explained by their differences in the metabolism as revealed by comparative metabolomics profiling: crucian carp demonstrated enhanced TCA cycle but reduced fatty acid biosynthesis; Our study also found that maltose was the most suppressed metabolite in fish grown at 33°C. Importantly, exogenous injection of maltose enhances crucian carp survival grown at 33°C by 30%. Further study showed that exogenous maltose downregulated the production of several cytokines but enhanced the lysozyme (lyz) and complement component c3, which involves the humoral innate immunity. Our results suggest that maltose promotes the survival of crucian carp likely through fine tuning the immune gene expression, and this finding provides a novel approach to manage bacterial infection.
Highlights
The fishery is recognized as an important sector in supplying nutrients to tackle micronutrient deficiency that causes one million premature deaths annually [1,2]
Crucian carp grown at 33°C was more susceptible to A. sobrial infection than those grown at 18°C
Differential metabolomes of crucian carps at 33°C and 18°C To explore the metabolic mechanism of why crucian carp survived better to A. sobrial infection at 18°C, we profiled the metabolome of crucian carp that were grown at these two different temperatures
Summary
The fishery is recognized as an important sector in supplying nutrients to tackle micronutrient deficiency that causes one million premature deaths annually [1,2]. As in the form of intensive farming, infectious disease is a major threat to the production in aquaculture [3]. Environmental factors, such as oxygen, water temperature, pH, and ammonia, influence the immune system of fish [4,5,6,7]. The mechanism of how temperature regulates the immune response of the fish is still poorly understood. Elucidating this mechanism would pave the way for establishing novel strategies in managing bacterial infection in aquaculture
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