A potential benefit of albinism in Astyanax cavefish: downregulation of the oca2 gene increases tyrosine and catecholamine levels as an alternative to melanin synthesis.
A potential benefit of albinism in Astyanax cavefish: downregulation of the oca2 gene increases tyrosine and catecholamine levels as an alternative to melanin synthesis.
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DOI：
10.1371/journal.pone.0080823
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Jeffery WR
中科院分区：
文献类型：
--
作者：
Bilandžija H;Ma L;Parkhurst A;Jeffery WR
白化病，即黑色素沉着的丧失，已经在各种洞穴动物中进化，但其进化机制尚不清楚。墨西哥Astyanax mexicanus是一种有色素的表面栖息形式（表层鱼）和几种白化穴居形式（洞穴鱼），白化是由oca2基因功能突变的丧失引起的，该基因在黑色素合成途径的第一步起作用。除了白化病，洞穴鱼还进化出了行为上的差异，包括进食和睡眠，这些都是由儿茶酚胺系统控制的。儿茶酚胺和黑色素的合成途径从相同的底物l -酪氨酸开始分化。在这里，我们描述了一种新的关系之间的儿茶酚胺和黑色素合成途径在黄芪。我们的研究结果表明，相对于表层鱼类，Pachón洞穴鱼的幼虫和成年大脑中l -酪氨酸、多巴胺和去甲肾上腺素的含量显著增加。此外，去甲肾上腺素在洞穴鱼成年肾脏中升高，其中含有硬骨鱼合成肾上腺细胞的儿茶酚胺的同系物。我们进一步表明，oca2基因在表层鱼的发育过程中表达，但在洞穴鱼的胚胎中被下调。一项重要的发现是，在表层鱼类胚胎中，oca2表达的下调会延缓黑色素细胞的发育，同时增加l -酪氨酸和多巴胺。我们得出结论，洞穴鱼白化的潜在进化益处可能是提供多余的l -酪氨酸作为升高的儿茶酚胺合成途径的前体，这可能对适应具有挑战性的洞穴环境很重要。
Albinism, the loss of melanin pigmentation, has evolved in a diverse variety of cave animals but the responsible evolutionary mechanisms are unknown. In Astyanax mexicanus, which has a pigmented surface dwelling form (surface fish) and several albino cave-dwelling forms (cavefish), albinism is caused by loss of function mutations in the oca2 gene, which operates during the first step of the melanin synthesis pathway. In addition to albinism, cavefish have evolved differences in behavior, including feeding and sleep, which are under the control of the catecholamine system. The catecholamine and melanin synthesis pathways diverge after beginning with the same substrate, L-tyrosine. Here we describe a novel relationship between the catecholamine and melanin synthesis pathways in Astyanax. Our results show significant increases in L-tyrosine, dopamine, and norepinephrine in pre-feeding larvae and adult brains of Pachón cavefish relative to surface fish. In addition, norepinephrine is elevated in cavefish adult kidneys, which contain the teleost homologs of catecholamine synthesizing adrenal cells. We further show that the oca2 gene is expressed during surface fish development but is downregulated in cavefish embryos. A key finding is that knockdown of oca2 expression in surface fish embryos delays the development of pigmented melanophores and simultaneously increases L-tyrosine and dopamine. We conclude that a potential evolutionary benefit of albinism in Astyanax cavefish may be to provide surplus L-tyrosine as a precursor for the elevated catecholamine synthesis pathway, which could be important for adaptation to the challenging cave environment.
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影响因子：
2.9
作者：
Bilandžija H;Cetković H;Jeffery WR
通讯作者：
Jeffery WR
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作者：
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