title: prdl-a, a gene marker for hydra apical differentiation related to triploblastic paired-like head-specific genes.
abstract: Two homeobox genes, prdl-a and prdl-b, which were isolated from a Hydra vulgaris cDNA library, encode paired-like class homeodomains highly related to that of the aristaless-related genes. In adult polyps, prdl-b is a marker for synchronously dividing nematoblasts while prdl-a displays an expression restricted to the the nerve cell lineage of the head region. During budding and apical regeneration, an early and transient prdl-a expression was observed in endodermal cells of the stump at a time when the head organizer is established. When apical regeneration was delayed upon concomittant budding, prdl-a expression was found to be altered in the stump. Furthermore, a specific anti-prdl-a protein immunoserum revealed that prdl-a was overexpressed in adult polyps of the Chlorohydra viridissima multiheaded mutant, with an expression domain extending below the tentacle ring towards the body column. Accordingly, prdl-a DNA-binding activity was enhanced in nuclear extracts from this mutant. These results suggest that prdl-a responds to apical forming signals and might thus be involved in apical specification. When a marine hydrozoan (Podocorynae carnea) was used, the anti-prdl-a antibody showed cross-reactivity with cells located around the oral region, indicating that prdl-a function is shared by other cnidaria. The ancestral role for prdl-a-related genes in the molecular definition of the head (or oral-surrounding region) is discussed.
authors.affiliation: Department of Zoology and Animal Biology, University of Geneva, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Gauchat
authors.forename: S
authors.initials: S
authors.lastname: Kreger
authors.forename: T
authors.initials: T
authors.lastname: Holstein
authors.forename: B
authors.initials: B
authors.lastname: Galliot
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015415:Biomarkers; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004475:Ectoderm / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox / Q000235:genetics*; D006257:Head / Q000002:abnormalities / Q000502:physiology; D018398:Homeodomain Proteins / Q000032:analysis* / Q000235:genetics; D006829:Hydra / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D012038:Regeneration; D014157:Transcription Factors
chemical_list: D015415:Biomarkers; D018076:DNA, Complementary; D018398:Homeodomain Proteins; C112761:Prdl-a protein, Hydra attenuata; C112762:Prdl-b protein, Hydra attenuata; D012333:RNA, Messenger; D014157:Transcription Factors; D004247:DNA