Meeting Abstract

56.4  Jan. 6  Relaxed selective constraints on Hox clusters of ray-finned fishes: Patterns and frequencies of mobile DNA element insertions RAINCROW, J.R.*; GAO, L.Z.; AMEMIYA, C.; CHIU, C.H.; Rutgers University; Rutgers University; VMRC, Seattle, Washington; Rutgers University raincrow@biology.rutgers.edu

Hox genes, which share sequence homology with the Hom-C genes of Drosophila, originated early in metazoan evolution and are distributed throughout the animal kingdom. Hox genes encode transcription factors that establish the body plan along the primary anterior-posterior axis (AP) extending from the mid-brain/hind-brain junction to the tail and the secondary proximo-distal (PD) axis of the limbs. Evidence to date suggests that jawed-vertebrates ancestrally possess four Hox clusters (A,B,C,D) and this condition is present in extant sharks, lobe-finned fishes, and basal ray-finned fishes. All derived ray-finned fishes (teleosts) examined to date possess at least seven Hox clusters. The Hox gene complex of chordates represents a highly constrained genetic system. Hox genes are organized in clusters (about 120 kilobases in humans) and do not exhibit gene duplications or re-arrangements. The nature of this constraint remains poorly understood. It is hypothesized that Hox cluster integrity is maintained largely due to the exclusion of mobile element insertions into Hox clusters. Mobile, or transposable elements, are prevalent in the genomes of animals and plants and are drivers of genome evolution. In this study, Repeat Masker (RM) was used to test for the presence of mobile elements (DNA transposons, autonomous retrotransposons, and nonautonomous retrotransposons) in Hox clusters of different jawed vertebrates.