Juvenile Hormone and the Evolution of Limb Patterning in Insect Metamorphosis

保幼激素和昆虫变态中肢体模式的进化

• 批准号: 9904959
• 负责人: James Truman
• 金额: $ 22.5万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9904959&HistoricalAwards=false
• 关键词: Juvenile; Hormone; Evolution; Limb; Patterning

The project examines the role of juvenile hormone (JH) in the evolution ofmetamorphosis and of the larval stage in insects. A key finding is thatin embryos of basal insect groups, JH suppresses the growth of embryonicprimordia and induces their precocious maturation. In insects withcomplete metamorphosis, by contrast, JH treatment has little effect onembryonic development but later application can suppress the resumption of"embryonic" growth that is the prelude to metamorphosis. An advancementin JH secretion during embryogenesis of the latter insects may haveprovided a mechanism by which a late embryonic instar, the pronymph, wasmodified to become an active, feeding larval stage characteristic ofinsects with complete metamorphosis.The proposal examines the effects of JH on the expression of three genesinvolved in proximal-distal (P-D) patterning of the leg: Distal-less (Dll),dachshund (dac), and rotund (rn). The objectives are: 1) to determine ifthe spatial and temporal expression of P-D patterning genes seen indeveloping leg imaginal discs in Drosophila also occurs during thepatterning of the embryonic leg in a more basal insect such as thegrasshoppers, Schistocerca americana; 2) test whether JH treatment tothese embryos during limb formation results in a truncation or alterationin P-D gene expression? 3) examine P-D gene expression in embryos of themoth, Manduca sexta, to determine if the novel leg of the caterpiller isassociated with a novel (truncated?) program of P-D gene expression; 4)examine the transition in P-D gene expression during metamorphosis and itssensitivity to juvenile hormone treatment.

该项目研究了保幼激素(JH)在昆虫变态和幼虫阶段进化中的作用。一个关键的发现是，在基础昆虫群的胚胎中，JH抑制了胚原基的生长并诱导了它们的早熟。相比之下，在完全变态的昆虫中，JH处理对胚胎发育影响不大，但后期使用可抑制变态的前奏--“胚胎”生长的恢复。在后两种昆虫胚胎发育过程中JH分泌的进展可能提供了一种机制，通过这种机制，胚胎晚期的前若虫被改造成活跃的、摄食的幼虫阶段，其特征是具有完全变态的部分。本方案研究了JH对参与腿部近端-远端(P-D)模式的三个基因表达的影响：远端无端(Dll)、腊肠(DAC)和圆形(Rn)。其目的是：1)确定在果蝇发育的腿想象盘中P-D模式基因的空间和时间表达是否也发生在更基本的昆虫如美洲血吸虫的胚胎腿的模式形成过程中；2)测试在肢体形成期间对这些胚胎进行JH处理是否会导致P-D基因表达的截断或改变？3)检测P-D基因在曼陀罗(Manduca Sexta)胚胎中的表达，以确定该幼虫的新腿是否与一种新的(截断？)P-D基因表达程序；4)检测变态过程中P-D基因表达的变化及其对保幼激素处理的敏感性。