title: Expression of homothorax and extradenticle mRNA in the legs of the crustacean Parhyale hawaiensis: evidence for a reversal of gene expression regulation in the pancrustacean lineage.
abstract: In Drosophila leg development, the extradenticle (exd) gene is expressed ubiquitously and its co-factor homothorax (hth) is restricted to the proximal leg portion. This condition is conserved in other insect species but is reversed in chelicerates and myriapods. As the region of co-expression does not differ in the two groups and transcripts from both are necessary for function, this difference in expression is likely to be functionally neutral. Here, we report the expression patterns of exd and hth in a crustacean, the amphipod shrimp Parhyale hawaiensis. The patterns in P. hawaiensis are similar to the insect patterns, supporting the close relationship between crustaceans and insects in the taxon Tetraconata. However, mRNA expression of exd in P. hawaiensis is weak in the distal leg parts, thus being intermediate between the complete lack of distal exd expression in chelicerates and myriapods and the strong distal exd expression in insects. Our data suggest that the reversal of the gene expression regulation of hth and exd occurred in the pancrustacean lineage.
authors.affiliation: Department of Developmental Biology, GZMB New Building, Georg-August-University Goettingen, Johann-Friedrich-Blumenbach Institute for Zoology and Anthropology, Justus-von-Liebig-Weg 11, Goettingen, Germany. nprpic@uni-goettingen.de
authors.forename: Nikola-Michael
authors.initials: NM
authors.lastname: Prpic
authors.forename: Maximilian J
authors.initials: MJ
authors.lastname: Telford
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000235:genetics; D003445:Crustacea / Q000196:embryology* / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics; D004625:Embryo, Nonmammalian; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D035002:Lower Extremity / Q000196:embryology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C083405:exd protein, Drosophila; C108704:hth protein, Drosophila