title: Progressive tarsal patterning in the Drosophila by temporally dynamic regulation of transcription factor genes.
abstract: The morphology of insect appendages, such as the number and proportion of leg tarsal segments, is immensely diverse. In Drosophila melanogaster, adult legs have five tarsal segments. Accumulating evidence indicates that tarsal segments are formed progressively through dynamic changes in the expression of transcription factor genes, such as Bar genes, during development. In this study, to examine further the basis of progressive tarsal patterning, the precise expression pattern and function of several transcription factor genes were investigated in relation to the temporal regulation of Bar expression. The results indicate that nubbin is expressed over a broad region at early stages but gradually disappears from the middle of the tarsal region. This causes the progressive expansion of rotund expression, which in turn progressively represses Bar expression, leading to the formation of the tarsal segment 3. The region corresponding to the tarsal segment 4 is formed when apterous expression is initiated, which renders Bar expression refractory to rotund. In addition, the tarsal segment 2 appears to be derived from the region that expresses Bar at a very early stage. Cessation of Bar expression in this region requires the function of spineless, which also regulates rotund expression. These findings indicate that the temporally dynamic regulatory interaction of these transcription factor genes is the fundamental basis of the progressive patterning of the tarsal region.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-city, Chiba 277-8562, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Natori
authors.forename: Reiko
authors.initials: R
authors.lastname: Tajiri
authors.forename: Shiori
authors.initials: S
authors.lastname: Furukawa
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kojima
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000033:anatomy & histology* / Q000196:embryology / Q000235:genetics*; D066246:ErbB Receptors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007814:Larva / Q000235:genetics; D008954:Models, Biological; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D066246:ErbB Receptors