Wang D, Marsh J L
Department of Developmental and Cell Biology, University of California Irvine 92717, USA.
Dev Biol. 1995 Apr;168(2):598-612. doi: 10.1006/dbio.1995.1105.
The insect cuticle is a highly differentiated structure exhibiting considerable variety and specialization. Part of this specialization is achieved by regulating the nature and/or extent of sclerotization. The dopa decarboxylase (Ddc) and alpha-methyldopa hypersensitive (l(2)amd) genes of Drosophila are structurally related and it has been shown that the Ddc gene is required for the proper sclerotization of pigmented cuticle as well as for neurotransmitter production. The physiological role of the amd gene is unknown. Following the pattern of amd expression during development, we find that it is expressed in tissues that secrete clear flexible (arthrodial) cuticle both internally and in specialized external structures. We present electron microscopic evidence that loss of amd function leads to cuticle defects in a region of amd expression. We also find that amd is expressed in the larval CNS and ring gland where it may be involved in neurotransmitter metabolism similar to its paralog, Ddc. Lymph glands also express amd suggesting a possible role in the immune response. The expression of amd in segmentally repeating stripes at the end of dorsal closure suggests that amd may be a terminal target of the segmentation gene hierarchy which specifies segments.
昆虫表皮是一种高度分化的结构，具有相当大的多样性和特异性。这种特异性的一部分是通过调节硬化的性质和/或程度来实现的。果蝇的多巴脱羧酶（Ddc）和α-甲基多巴超敏（l(2)amd）基因在结构上相关，并且已经表明Ddc基因对于有色表皮的正常硬化以及神经递质的产生是必需的。amd基因的生理作用尚不清楚。按照amd在发育过程中的表达模式，我们发现它在内部以及专门的外部结构中分泌透明柔韧（关节）表皮的组织中表达。我们提供了电子显微镜证据，表明amd功能丧失会导致amd表达区域的表皮缺陷。我们还发现amd在幼虫中枢神经系统和环腺中表达，在那里它可能与其旁系同源基因Ddc类似地参与神经递质代谢。淋巴腺也表达amd，表明其在免疫反应中可能发挥作用。在背闭合结束时，amd在节段性重复条纹中的表达表明amd可能是指定节段的节段基因层级的终端靶点。
