Molecular evolution of leptin

Leptin, a hormone produced mainly by adipocytes, is involved in the regulat ion of food intake, metabolism, and reproduction. The objective of this stu dy was to determine the evolutionary relationships of leptin genes. Partial nucleotide sequences of leptin were cloned and sequenced from six mammalia n species: large hairy armadillo (Chaetophractus villosus), rabbit (Oryctol agus cuniculus), little brown bat (Myotis lucifugus), striped skunk (Mephit is mephitis), raccoon (Procyon lotor), and beluga whale (Delphinapterus leu cas). The PUZZLE program was used to construct maximum-likelihood trees. Ou r phylogenetic analysis shows that the grouping of these new mammalian sequ ences with those currently available in GenBank respect the evolutionary re lationships generally accepted for mammals. However, when leptin sequences for chicken and turkey are included in the analysis, these are found to gro up with mouse and rat leptins. Chicken and mouse leptins are 95% identical. However, when mouse is compared with closer relatives, such as rabbit or b at, identities are approximately 80%. A comparison of extant and ancestral leptin sequences suggests that convergent or parallel evolution is the most plausible hypothesis to explain the similarity between bird and rodent lep tins. (C) 2001 Academic Press.