Functional conservation and divergence of duplicated fibroblast growth factor receptor 1 (fgfr1) genes in blunt snout bream (Megalobrama amblycephala)

Abstract

Fgfr1 is a fibroblast growth factor receptor involved in regulating cell growth, proliferation, differentiation and migration. Here, we report the isolation and characterization of duplicated fgfr1 genes in blunt snout bream (Megalobrama amblycephala). Blunt snout bream fgfr1a and -1b cDNAs were found to share a relatively high sequence identity of 82%. During embryogenesis, both fgfr1a and -1b mRNAs were highly detected at zygotes but gradually decreased and then constantly expressed after 16hpf, besides a strong expression for the fgfr1b mRNA at 12hpf. Whole-mount in situ hybridization demonstrated that fgfr1a mRNA was transcribed at the eyes, mid-hindbrain boundary (MHB), brain, posterior somites and tailbud at 16hpf, while the fgfr1b mRNA was only detected at the eyes and posterior somites at the same period. At 28hpf embryos, both fgfr1a and -1b mRNAs were expressed in the eyes, brain, pharyngeal arches and tailbud, and in the eyes, brain, pharyngeal arches and notochord at 55hpf. In adult fish, fgfr1a mRNA was strongly expressed in the gill, gonad, brain and midgut, but examined relatively low in the skin and kidney. In contrast, the fgfr1b mRNA was highly detected in the brain and liver and quite low in the skin, gill and kidney. During starvation, both fgfr1a and -1b mRNAs were significantly up-regulated in the intestine and liver, but down-regulated in the brain. Moreover, duplicated fgfr1 mRNAs were differentially inhibited in tissues with exogenous recombinant hGH. Our results suggest that two fgfr1 genes play important roles in regulating growth and development in blunt snout bream.