Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan.
Dev Genes Evol. 2010 Jun;220(1-2):53-9. doi: 10.1007/s00427-010-0325-5. Epub 2010 May 7.
Larvae of the sawfly, Athalia rosae, have remarkable abdominal prolegs. We analyzed the morphogenesis of appendages and the expression of decapentaplegic and Distal-less genes during embryonic development to characterize the origin of prolegs. Proleg primordia in abdominal segments A1-A9 appeared shortly after the inner lobes (endites) of gnathal appendages were formed. These were located on the ventral plates, medioventral to the appendages of the other segments in light of serial homology. Nothing was seen where the main axis of the appendage should develop in abdominal segments. The primordia in A1 and A9 disappeared before larval hatching. Anal prolegs appeared separate from cerci, the main axes of appendages, which were formed temporarily in A11. The expression of decapentaplegic, which reflects the primary determination of appendages, was detected in the lateral juxtaposition with the prolegs. Distal-less was expressed in the main axes of appendages, protruding endites and the cerci, but not in prolegs and anal prolegs or the gnathal endites which do not protrude. These findings suggest a possibility that the abdominal and anal prolegs of A. rosae are outgrowths of ventral plates which derived from coxopodal elements, but not main axes of appendages.
蔷薇三节叶蜂的幼虫具有显著的腹足。我们分析了胚胎发育过程中附肢的形态发生和 Decapentaplegic 和 Distal-less 基因的表达，以确定腹足的起源。在咀嚼附肢的内叶（端节）形成后不久，A1-A9 节的腹足原基出现。这些原基位于腹侧板上，与其他节的附肢的中腹侧相对，根据系列同源性。在应该形成附肢主轴的腹部节段中没有看到任何东西。A1 和 A9 节的原基在幼虫孵化前消失。肛足与附肢的主轴分开出现，主轴在 A11 中暂时形成。反映附肢初步确定的 Decapentaplegic 的表达在与腹足相邻的位置被检测到。Distal-less 在附肢的主轴、突出的端节和尾铗中表达，但不在腹足和肛足中表达，也不在不突出的咀嚼端节中表达。这些发现表明，蔷薇三节叶蜂的腹部和肛足可能是源自后胸附肢的侧板外突，但不是附肢的主轴。
