Chen_2001_Biochem.Biophys.Res.Commun_285_105

The cDNA sequence of beta crystallin B1 was determined from zebrafish (Danio rerio) and compared to the corresponding genes of bovine, rat, chicken, human, and Xenopus. Multispecies comparison of superfamily diversity demonstrated beta crystallin B1 homology between zebrafish, bovine, chicken, and rat, but large distances to beta crystallin B2 and B3. Zebrafish cDNA has a size of 943 nucleotides and encodes a polypeptide of 233 amino acids. Zebrafish beta crystallin B1 shares 71.30, 75.86, and 71.00% similarities with bovine, chicken, and rat beta crystallin B1, respectively. Northern blot analysis revealed a single 0.9-kb beta crystallin B1 transcript which was expressed and progressively increased in the first 20 h of zebrafish embryogenesis. Whole-mount in situ hybridization revealed that the beta crystallin B1 transcript was only specifically expressed in the lens region of the eye. A starvation experiment revealed no variation in mRNA levels after 14 and 21 days. An experiment in which hormone was injected showed that the beta crystallin B1 transcript first increased 24 h after the injection of insulin-like growth factor I, insulin-like growth factor II, or growth hormone, then decreased 48 h after injection. The beta crystallin B1 transcript continuously increased after insulin was injected. Taken together, our results identify the early specific expression of beta crystallin B1 within the lens. Despite small differences, these results indicate that both the structure of the beta crystallin B1 protein and its involvement with regulation by growth factors appear to have been remarkably conserved.