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The presence and expression of the HIF-1α in the respiratory intestine of the bronze Corydoras Corydoras aeneus (Callichthyidae Teleostei)

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Bronze corydoras (Corydoras aeneus) is a small diurnal activity fish from South America. Under hypoxia conditions, it uses the posterior part of the intestine as an accessory respiratory organ. The present PCR studies demonstrated higher expression of HIF-1α (hypoxia-inducible factor) gene in the respiratory than that in digestive part of bronze corydoras intestine. Further, immunolocalization studies using antibodies specific to HIF-1α and transmission electron microscopy (TEM) revealed the presence of HIF-1α epitopes in the intestine of Corydoras aeneus. In the respiratory intestine, the numerous clusters of gold particles visualizing HIF-1α antibody were observed within fibroblasts, whereas in the digestive tract of this species, single gold grains in the epithelial cells were noted. On the other hand, the presence of HIF-1α and the cytoplasmic domain of the epidermal growth factor receptor (EGFR) in the respiratory intestine of bronze corydoras assumes their interactions in the system where these factors appeared for the first time. The non-obligatory air-breathing fishes using their digestive tract as an accessory respiratory organ during hypoxia conditions are very interesting for the studies of the processes that control HIF-1α expression and squamous cell proliferation.
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... When the DO in water exceeds 5 mg/L, fish can carry out normal life activities; however, when the DO content is reduced to 2-3 mg/L, fish will appear floating on their head. When DO is < 1 mg/L, most fish will die due to a lack of oxygen (Satora et al. 2018). Hypoxia has occurred in cobia fish culture areas in recent years, due to a number of factors (Diaz 2001;Vaquer-Sunyer and Duarte 2008;Lai et al. 2016), such as water temperature, season, and culture density. ...
... It then affects proteins and cytokines, which alter behavior, growth and development, physiology, biochemistry, and metabolism, resulting in a decrease in growth, reproduction, and immunity. Finally, hypoxia affects the energy flow and ecological characteristics of the population (Satora et al. 2018;Chang et al. 2018;Jenne and Kubes 2013). Hence, the molecular mechanisms of cobia fish in response to hypoxia should be investigated. ...
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