Eye stalks or no eye stalks:: A structural comparison of pupal development in the stalk-eyed fly Cyrtodiopsis and in Drosophila
Eye stalks or no eye stalks:: A structural comparison of pupal development in the stalk-eyed fly Cyrtodiopsis and in Drosophila
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DOI：
10.1002/cne.1155
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发表时间：
2001-05-14
影响因子：
2.5
通讯作者：
Hoy, RR
中科院分区：
文献类型：
--
作者：
Buschbeck, EK;Roosevelt, JL;Hoy, RR
从蛹中出来后，茎眼蝇科的茎眼蝇迅速扩张其头囊，使得眼睛和视叶移位到从中央头部延伸的茎的末端。由于扩张仅在 15 分钟内发生，因此我们对可能促进如此快速和戏剧性变化的个体发育修饰特别感兴趣。为了检查大脑的蛹发育，我们在茎眼蝇（Cyrtodiopsiswhitei）中使用了博迪安染色，并将其与果蝇（Drosophila melanogaster）的发育进行了比较，果蝇是没有眼柄的“典型”双翅目例子。在蛹发育的早期，两个物种的神经纤维组织非常相似。在这两个物种中，外髓中都存在柱，小叶板中可辨别出巨大的纤维。与黑腹果蝇相反，怀特果蝇的视叶和大脑其他部分之间有一个小的颈状收缩。到蛹发育 20% 时，这种分化更加明显，到 30% 时，C.whitei 未来的眼柄和视神经已经开始形成。在剩下的 70% 的发育过程中，最初粗的视神经变窄，并逐渐拉长，最终在整个短眼柄中卷曲和折叠。同样，周围区域的角质层也变得收缩，稍微拉长，逐渐呈现出越来越密的波纹，就像手风琴的风箱一样。然而，除了视神经的形成、周围角质层的密集聚集以及神经细胞方向的转变之外，这两个物种的发育程序非常相似。这表明在进化过程中仅改变了发育的几个方面以产生茎眼表型。羽化时，C. Whitei 的图像会经历泵送过程，使眼柄膨胀至全长。扩张前后视神经直径的测量显示仅小幅减小。我们认为，眼柄的角质层折叠以及视神经的卷绕为蛹在羽化后迅速而戏剧性的眼柄膨胀做好了充分的准备。 (C) 2001 Wiley-Liss, Inc.
After emergence from the puparium, stalk-eyed flies of the family Diopsidae rapidly expand their head capsule so that the eyes and optic lobes are displaced at the ends of stalks that extend from the central head. Because the expansion takes place in only 15 minutes, we are especially interested in ontogenetic modifications that may facilitate such a rapid and dramatic change. To examine the pupal development of the brain, we used Bodian staining in the stalk-eyed fly, Cyrtodiopsis whitei and compared it with development in the fruit fly, Drosophila melanogaster, which serves as a "typical" dipteran example without eye stalks. Early in pupal development, the neuropil organization of the two species is fairly similar. In both species, columns are present in the outer medulla and giant fibers are discernible in the lobula plate. In contrast to D. melanogaster, C. whitei shows a small, neck-like constriction between the optic lobes and the rest of the brain. By 20% of pupal development, the divergence is more apparent, and by 30%, the future eye stalk and optic never of C. whitei has started to form. During the remaining 70% of development, the initially thick optic nerve narrows, and becomes gradually elongated, eventually coiling and folding throughout the short eye stalk. Similarly, the cuticle of the surrounding region becomes constricted, slightly elongated, and gradually appears more and more densely corrugated, like an accordion bellows. However, except for the formation of the optic nerve, the dense aggregation of cuticle around it, and a shift in orientation of the neuropils, the developmental programs of the two species are remarkably similar. This suggests that only a few aspects of development have been modified during the course of evolution to generate the stalk-eyed phenotype. At eclosion, the image of C. whitei goes through a pumping process to inflate the eye stalks to their full length. Measurements of the diameter of the optic nerve before and after the expansion reveal only a small decrease. We propose that the cuticular folding of the eye stalk as well as the coiling of the optic nerve prepare the pupa well for the rapid and dramatic eye-stalk inflation after eclosion. (C) 2001 Wiley-Liss, Inc.