title: The identification and expression of achaete-scute genes in the branchiopod crustacean Triops longicaudatus.
abstract: The achaete-scute (ac/sc) genes are a highly conserved family of transcription factors that play important roles in the development of neural cells in both vertebrates and invertebrates. As such, the study of arthropod ac/sc gene expression during neurogenesis has become a model system for investigating the evolution of neural patterning. To date, ac/sc gene expression has been investigated in insects, chelicerates, and myriapods. Here we present the identification of two ac/sc genes from the branchiopod crustacean Triops longicaudatus. Triops longicaudatus achaete-scute homologs1 and 2 (Tl-ASH1 and Tl-ASH2) exhibit dynamic and distinct expression profiles during Triops neurogenesis. Tl-ASH1 expression initiates in nearly all cells of the neurogenic region and subsequently in clusters of cells evenly spaced along the length of the developing limbs. In contrast, Tl-ASH2 initiates expression after Tl-ASH1. In the CNS, only a subset of Tl-ASH1 cells appears to express Tl-ASH2. Similarly, in the PNS individual Tl-ASH2 positive cells appear to arise from the clusters of Tl-ASH1 expressing cells. Shortly after activating Tl-ASH2 expression, these cells enlarge and divide. The expression dynamics of ac/sc genes in Triops parallel those observed in insects and contrasts with those found in chelicerates and myriapods.
authors.affiliation: Department of Genetics, Washington University School of Medicine, St Louis, MO 63110, USA. wheelers@email.unc.edu
authors.forename: Scott R
authors.initials: SR
authors.lastname: Wheeler
authors.forename: James B
authors.initials: JB
authors.lastname: Skeath
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003445:Crustacea; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry*; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000096:biosynthesis* / Q000737:chemistry*
chemical_list: D004268:DNA-Binding Proteins; D014157:Transcription Factors