title: Hox Gene Loss during Dynamic Evolution of the Nematode Cluster.
abstract: HOX GENES ARE IMPORTANT: their central role in anterior-posterior patterning provides a framework for molecular comparison of animal body plan evolution. The nematode Caenorhabditis elegans stands out as having a greatly reduced Hox gene complement. To address this, orthologs of C. elegans Hox genes were identified in six species from across the Nematoda, and they show that rapid homeodomain sequence evolution is a general feature of nematode Hox genes. Some nematodes express additional Hox genes belonging to orthology groups that are absent from C. elegans but present in other bilaterian animals. Analysis of the genomic environment of a newly identified Brugia malayi Hox6-8 ortholog (Bm-ant-1) revealed that it lay downstream of the Bm-egl-5 Hox gene and that their homeodomain exons are alternately cis spliced to the same 5' exon. This organization may represent an intermediate state in Hox gene loss via redundancy. The Hox clusters of nematodes are the product of a dynamic mix of gene loss and rapid sequence evolution, with the most derived state observed in the model C. elegans.
authors.affiliation: Institute of Cell, Animal and Population Biology, University of Edinburgh, EH9 3JT, Scotland, Edinburgh, United Kingdom. aziz.aboobaker@ed.ac.uk
authors.forename: A Aziz
authors.initials: AA
authors.lastname: Aboobaker
authors.forename: Mark L
authors.initials: ML
authors.lastname: Blaxter
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D003001:Cloning, Molecular; D017353:Gene Deletion; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics; D005810:Multigene Family; D009348:Nematoda / Q000235:genetics*; D010802:Phylogeny; D014157:Transcription Factors
chemical_list: D029742:Caenorhabditis elegans Proteins; C477318:Egl-5 protein, C elegans; D018398:Homeodomain Proteins; D014157:Transcription Factors