Terrestrial Vertebrates Have Two Keratin Gene Clusters; Striking Differences in Teleost Fish

The study analyzed the genomic sequences of chicken (Gallus gallus) and the amphibian Xenopus tropicalis to investigate the presence of keratin gene clusters, which are known to exist in mammals. It was found that both species have keratin type I and II gene clusters, with the chicken having a type I cluster on chromosome 27 and a type II cluster of unknown location. The study also examined teleost fish genomes, revealing a significant excess of type I over type II keratin genes, unlike the more balanced distribution seen in terrestrial vertebrates. This suggested that keratin gene clusters evolved with vertebrates, but teleost fish exhibited notable differences in keratin gene distribution compared to terrestrial vertebrates.