Pigmentation in the sensory organs of the ascidian larva is essential for normal behavior
Pigmentation in the sensory organs of the ascidian larva is essential for normal behavior
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DOI：
10.1242/jeb.01420
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发表时间：
2005-02-01
影响因子：
2.8
通讯作者：
Smith, WC
中科院分区：
文献类型：
--
作者：
Jiang, D;Tresser, JW;Smith, WC
自由生活的动物和它们的幼虫利用光和重力作为在开放空间中导航的线索。对这些环境刺激的检测和响应对于海鞘幼虫的扩散和定居是重要的。海鞘幼体脑内的两个色素结构，眼细胞和耳石，已被证明分别作为光感受器官和重力敏感器官。在这里，我们表明，色素沉着是必要的适当的趋光性和趋地性行为的海鞘种玻璃海鞘幼虫。两个隐性和互补突变株系的C savignyi，完美无瑕和一尘不染，专门破坏色素沉着的感觉器官在幼虫发育过程中进行了描述。纯合子突变幼虫不能正确地响应重力和照明线索，而解决。遗传分析表明，一尘不染是由酪氨酸酶基因内的一个点突变引起的，该突变产生了一个过早的终止密码子，而完美无瑕的分子性质尚不清楚。尽管色素沉着在萨氏梭子蟹眼球中的作用与脊椎动物视觉系统中的作用相似，但我们的结果表明黑色素在趋地行为中的新用途。
Free-living animals and their larvae utilize light and gravity as cues to navigate in open space. Detection and response to these environmental stimuli are important for the dispersal and settlement of ascidian larvae. Two pigmented structures in the brain of the ascidian larva, the ocellus and the otolith, have been shown to function as the photoreceptive and gravity sensitive organs, respectively. Here, we show that pigmentation is essential for proper phototactic and geotactic behavior in larvae of the ascidian species Ciona savignyi. Two recessive and complementing mutant lines of C savignyi, immaculate and spotless, that specifically disrupt the pigmentation of the sensory organs during larval development are described. Homozygous mutant larvae are unable to respond properly to gravity and illumination cues while settling. Genetic analysis shows that spotless is caused by a point mutation within the tyrosinase gene that creates a premature stop codon, while the molecular nature of immaculate is unknown. Although the role of pigmentation in the ocellus of C savignyi is similar to that in vertebrate visual systems, our results demonstrate a novel use of melanin in geotactic behavior.