Broad specifies pupal development and mediates the 'status quo' action of juvenile hormone on the pupal-adult transformation in Drosophila and Manduca.
Broad specifies pupal development and mediates the 'status quo' action of juvenile hormone on the pupal-adult transformation in Drosophila and Manduca.
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发表时间：
2002-05
期刊：
影响因子：
4.6
通讯作者：
Xiaofeng Zhou;L. Riddiford
中科院分区：
文献类型：
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作者：
Xiaofeng Zhou;L. Riddiford
鳞翅目昆虫和双翅目昆虫对保幼激素（JH）的反应存在很大差异，这阻碍了对昆虫变态内分泌调控的分子基础的理解。在Manduca和果蝇中，broad（br）基因在蛹形成期间在表皮中表达，但在成虫分化期间不表达。BR-Z1在果蝇幼虫或成虫蜕皮期间的错误表达抑制了阶段特异性角质层基因并激活了蛹角质层基因，表明br是蛹阶段的主要指定者。在成虫蜕皮开始时用JH模拟物处理会导致br重新表达和在Manduca中形成第二个蛹角质层，但仅在果蝇的腹部。表达的BR异构体在果蝇的成年发展过程中抑制刚毛和毛发的形成时，诱导早期或重定向角质层生产蛹程序时，诱导晚。BR-Z1在这两个时间的表达模拟了JH应用的效果，但与JH不同的是，它导致在头部和胸部以及腹部产生新的蛹角质层。因此，JH对蛹-成虫转化的“现状”作用是由JH诱导的BR再表达介导的。
The understanding of the molecular basis of the endocrine control of insect metamorphosis has been hampered by the profound differences in responses of the Lepidoptera and the Diptera to juvenile hormone (JH). In both Manduca and Drosophila, the broad (br) gene is expressed in the epidermis during the formation of the pupa, but not during adult differentiation. Misexpression of BR-Z1 during either a larval or an adult molt of Drosophila suppressed stage-specific cuticle genes and activated pupal cuticle genes, showing that br is a major specifier of the pupal stage. Treatment with a JH mimic at the onset of the adult molt causes br re-expression and the formation of a second pupal cuticle in Manduca, but only in the abdomen of Drosophila. Expression of the BR isoforms during adult development of Drosophila suppressed bristle and hair formation when induced early or redirected cuticle production toward the pupal program when induced late. Expression of BR-Z1 at both of these times mimicked the effect of JH application but, unlike JH, it caused production of a new pupal cuticle on the head and thorax as well as on the abdomen. Consequently, the 'status quo' action of JH on the pupal-adult transformation is mediated by the JH-induced re-expression of BR.