Sequencing and Characterization of Hox gene clusters in Japanese Lamprey (Lethenteron Japonicum)

Abstract

Cyclostomes (comprising lampreys and hagfishes) are the sister group of living jawed vertebrates and therefore an important group for understanding the origin and diversity of vertebrates. In vertebrates and most metazoans, Hox genes determine positional identities along the developing embryo and are implicated in driving morphological diversity. Invertebrates typically contain a single Hox cluster (either intact or fragmented) whereas elephant shark, coelacanth and tetrapods contain four Hox clusters owing to two rounds (`1R? and `2R?) of whole-genome duplication during early vertebrate evolution. By contrast, most teleost fishes contain up to eight Hox clusters due to an additional genome duplication event (`3R?) in the ray-finned fish lineage. In my project, using a combination of BAC sequences and scaffold sequences from a draft genome assembly, I provide evidence for at least six Hox clusters in the Japanese lamprey. This suggests that the lamprey lineage has experienced an additional round of genome duplication.