HOM/Hox type homeoboxes in the chelicerate Limulus polyphemus.
The polymerase chain reaction was used to survey HOM/Hox type homeobox genes in the North American horseshoe crab, Limulus polyphemus. The survey reveals 28 different homeobox fragments possessing 44-80% nucleotide sequence similarity with HOM-C sequences in Drosophila and Hox B sequences in mouse. Limulus has one to four representatives of HOM/Hox cognates when fragments are assigned according to amino acid identity. A parsimony analysis including the Limulus sequences and homologous mouse Hox B and Drosophila HOM-C sequences reveals several instances of monophyletic groupings of Limulus homeoboxes with a Drosophila or mouse gene as the sister branch. Under the current model of HOM/Hox cluster evolution, these results suggest that Limulus has as many as four HOM/Hox type clusters. This is the first evidence suggesting the presence of multiple clusters in a nonvertebrate taxon. Putative homologs of mouse Hoxb-3 in Limulus suggest that the gene was present in the common ancestor of arthropods and vertebrates and has been lost in Drosophila.
Cartwright
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Department of Biology, Yale University, New Haven, Connecticut 06511.
Dick
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Buss
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D004330:Drosophila / Q000235:genetics; D005801:Genes, Homeobox; D006737:Horseshoe Crabs / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D009656:North America; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D017386:Sequence Homology, Amino Acid; D014714:Vertebrates / Q000235:genetics