Abstract
Adaptation to hypoxia is a complex process involving various pathways and regulation mechanisms. A better understanding of the genetic influence on these mechanisms could permit selection for hypoxia-sensitive fish. To aid this understanding, an integrated analysis of miRNA and mRNA expression was performed in Megalobrama amblycephala under four acute hypoxia and reoxygenation stages. A number of significantly differentially-expressed miRNAs and genes associated with oxidative stress were identified, and their functional characteristics were revealed by GO function and KEGG pathway analysis. They were found to be involved in HIF-1 pathways known to affect energy metabolism and apoptosis. MiRNA-mRNA interaction pairs were detected from comparison of expression between the four different stages. The function annotation results also showed that many miRNA-mRNA interaction pairs were likely to be involved in regulating hypoxia stress. As a unique resource for gene expression and regulation during hypoxia and reoxygenation, this study could provide a starting point for further studies to better understand the genetic background of hypoxia stress.
Highlights
Hypoxia in fish can lead to adverse effects on growth, behaviour, reproduction and overall survival[1,2,3,4,5,6]
Approximately 416,787,182 high-quality reads with a Q20 percentage of 96.51% and GC percentage of 46.08% were available for analysis (Table 1)
A total of 279,747 unigenes were generated with an average length of 534 bp (Table 1)
Summary
Hypoxia in fish can lead to adverse effects on growth, behaviour, reproduction and overall survival[1,2,3,4,5,6]. Under the condition of hypoxia, or hypoxia followed by reoxygenation, oxygen reacts with various chemical species including accumulated electrons via the one-electron mechanism in mitochondria, and with accumulated degradation products such as hypoxanthine and xanthine. The blunt snout bream, known as the Wuchang bream (Megalobrama amblycephala), is a herbivorous freshwater fish that is farmed commercially in China It is distributed in the affiliated lakes of the Yangtze River, such as Liangzi Lake, Poyang Lake and Yuni Lake[13,14,15]. It has long been recognised as one of the most important freshwater species[16], it is not suitable for high-density pond farming because of its relatively low hypoxia threshold. This sensitivity to hypoxia has implications for the welfare and culture of M. amblycephala, it could allow this species to be used as a model organism to explore the molecular mechanisms of acute hypoxia and reoxygenation via the transcriptome
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