title: Region-specific expression of mario reveals pivotal function of the anterior nondigit region on digit formation in chick wing bud.
abstract: We report the region-specific expression of a novel gene, named mario, whose expression domain is in the distal tip of the presumptive and developing digit 2 region in the developing chick wing bud. The anterior region-specific expression of mario corresponds well with the presence of digit 2, and fate map analysis showed that mario expression at early stages represents the presumptive digit 2 region. Using mario expression as a region-specific marker for the digit 2 region, several surgical operations were performed to obtain insights into digit 2 development in the chick wing. Cell fate tracing concomitant with a zone of polarizing activity (ZPA) implantation revealed that an additional digit 2 in the ZPA implantation into the anterior or middle region of wing bud is derived from the original digit 2 region (mario-positive region). Surgical manipulations revealed that the anterior nondigit region has an inhibitory effect on digit 2 formation. Taken together, these results suggest that the most-anterior region, including the anterior necrotic zone, restricts the position of digit 2 region by limiting the anterior border of the digit 2 region and preventing its expansion.
authors.affiliation: Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama Aoba-ku, Sendai, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Amano
authors.forename: Koji
authors.initials: K
authors.lastname: Tamura
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000235:genetics* / Q000378:metabolism*; D015415:Biomarkers; D002642:Chick Embryo; D018076:DNA, Complementary / Q000235:genetics; D004475:Ectoderm / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D006801:Humans; D018878:Limb Buds / Q000196:embryology* / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism; D009928:Organ Specificity; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics; D014921:Wings, Animal / Q000196:embryology* / Q000378:metabolism*
chemical_list: D030161:Avian Proteins; D015415:Biomarkers; D018076:DNA, Complementary; D022661:RNA, Untranslated