Postembryonic development of sexually dimorphic glomeruli and related interneurons in the cockroach Periplaneta americana
Postembryonic development of sexually dimorphic glomeruli and related interneurons in the cockroach Periplaneta americana
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DOI：
10.1016/j.neulet.2009.11.044
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发表时间：
2010-01-18
影响因子：
2.5
通讯作者：
Mizunami, Makoto
中科院分区：
文献类型：
--
作者：
Nishino, Hiroshi;Yoritsune, Atsushi;Mizunami, Makoto
在大多数昆虫中，性信息素是由雄性触角叶（一级嗅觉中心）的一个增大的肾小球复合体（macroglomerular complex， MGC）处理的。美洲蟑螂的肾小球由两个紧密相连的A-肾小球和b -肾小球组成，它们分别负责处理主要的性信息素成分——环planone-A和- b。利用顺行性染料注射，研究了感觉传入和中间神经元的两性二态性。A型和b型肾小球存在于雌雄幼虫的第一阶段。雌性MGC同源体在整个发育过程中以相对恒定的速度生长（每次蜕皮生长1.2-1.8倍），而雄性MGC在第5 ~ 9龄之间表现出一段加速生长的时期，单次蜕皮的体积可以增加一倍以上。这些不同的生长模式导致成年女性与男性肾小球复合体体积的比例为1:30。在雌性MGC同系物中，来自背侧和腹侧触角表面的传入信号偏向前部和后部区域，与成年雄性相比，这些传入信号的分离不太清楚。对投射到原脑的中间神经元的染色表明，雄性在8龄后期出现了性信息素加工特征的投射模式，而雌性可能的同类投射数量要少得多。这些结果表明，在8岁前的雄性幼虫，可能还有雌性幼虫，肾小球复合物没有分化以特异性检测性信息素。对性信息素检测的男性特异性投射可能是通过修改已有的神经回路形成的。2009爱思唯尔爱尔兰有限公司版权所有。
In most insects, sex pheromone is processed by an enlarged glomerular complex (macroglomerular complex, MGC) in the male antennal lobe (first-order olfactory center). The MGC of the American cockroach consists of two closely located A- and B-glomeruli which are responsible for processing the major sex pheromone components, periplanone-A and -B, respectively. Using anterograde dye injection, we investigated sexual dimorphism in sensory afferents and interneuron. The A- and B-glomeruli exist in the first larval instar of both sexes. The female MGC homolog grows at a relatively constant rate (1.2-1.8-fold growth per molt) throughout development, whereas the male MGC shows a period of accelerated growth between the fifth and ninth instars, where volume can be more than double in a single molt. These different growth patterns resulted in a 1:30 ratio in glomerular complex volumes of adult females versus males. In the female MGC homolog, afferents originating from the dorsal and ventral antennal surfaces were biased toward anterior and posterior regions, and segregation of these afferents was less clear compared to the adult male. The staining of interneurons projecting to the protocerebrum revealed that projection patterns characteristic of sex pheromone processing appear in the late eighth instar in males, while possibly homologous projections in the female were far fewer in number. These results suggest that the glomerular complexes in pre-eighth larval males, and probably females, are not differentiated for specific detection of sex pheromone. Male-specific projections for sex pheromone detection may be formed by modification of pre-existing neural circuitry. (C) 2009 Elsevier Ireland Ltd. All rights reserved.