Physiological genomics
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Physiological genomics · Oct 2006
Early developmental expression of two insulins in zebrafish (Danio rerio).
We have cloned a second insulin gene in zebrafish and studied temporal and spatial expression of two zebrafish insulin genes. Zebrafish insulin-a (insa) and -b (insb) mRNAs are derived from two different DNA contigs on chromosomes 5 and 14, respectively, representing two different insulin genes. Real-time PCR studies suggest that insa is a maternal and also a postzygotic transcript. insa was observed at 1 h postfertilization (hpf) and was rapidly degraded by 6 and 12 hpf but induced at 24 hpf (i.e., after pancreas formation). ⋯ At later time points, insb expression was restricted to the brain and pancreas (24 and 48 hpf). insa expression was observed in the pancreas at 24 and 48 hpf. Expression of insb in blastomeres and head suggests that insb could be acting as a pro-growth, survival, and neurotrophic factor during development. Pancreatic insa and insb may both be involved in regulation of glucose homeostasis as in mammals.