Windsor Diana J, Owens Gregory L
Department of Biology, University of Victoria, 3800 Finnerty Rd, Victoria, British Columbia, Canada.
BMC Res Notes. 2009 Aug 5;2:159. doi: 10.1186/1756-0500-2-159.
Jenynsia onca, commonly known as the one sided livebearer, is a member of the family Anablepidae. The opsin gene repertoires of J. onca's close relatives, the four-eyed fish (Anableps anableps) and the guppy (Poecilia reticulata), have been characterized and each found to include one unique LWS opsin. Currently, the relationship among LWS paralogs and orthologs in these species are unclear, making it difficult to test the hypotheses that link vision to morphology or life history traits. The phylogenetic signal appears to have been disrupted by gene conversion. Here we have sequenced the opsin genes of J. onca in order to resolve these relationships.
We identified nine visual opsins; LWS S180r, LWS S180, LWS P180, SWS1, SWS2A, SWS2B, RH1, RH2-1, and RH2-2. Key site analysis revealed only one unique haplotype, RH2-2, although this is unlikely to shift lambdamax significantly. LWS P180 was found to be a product of a gene conversion event with LWS S180, followed by convergence to a proline residue at the 180 site.
Jenynsia onca has at least 9 visual opsins: three LWS, one RH1, two RH2, one SWS1 and two SWS2. The presence of LWS P180 moves the location of the LWS P180-S180 tandem duplication event back to the base of the Poeciliidae-Anablepidae clade, expanding the number of species possessing this unusual blue shifted LWS opsin. The presence of the LWS P180 gene also confirms that gene conversion events have homogenized opsin paralogs in fish, just as they have in humans.
詹氏食蚊鱼（Jenynsia onca），通常被称为单侧胎生鱼，是食蚊鱼科的一员。詹氏食蚊鱼的近亲四眼鱼（Anableps anableps）和孔雀鱼（Poecilia reticulata）的视蛋白基因库已被表征，并且各自发现包含一种独特的长波光敏感视蛋白（LWS opsin）。目前，这些物种中长波光敏感视蛋白旁系同源物和直系同源物之间的关系尚不清楚，这使得难以检验将视觉与形态或生活史特征联系起来的假设。系统发育信号似乎已被基因转换破坏。在这里，我们对詹氏食蚊鱼的视蛋白基因进行了测序，以解决这些关系。
我们鉴定出9种视觉视蛋白；长波光敏感视蛋白S180r、长波光敏感视蛋白S180、长波光敏感视蛋白P180、短波敏感视蛋白1（SWS1）、短波敏感视蛋白2A（SWS2A）、短波敏感视蛋白2B（SWS2B）、视紫红质1（RH1）、视紫红质2-1（RH2-1）和视紫红质2-2（RH2-2）。关键位点分析仅揭示了一种独特的单倍型，即视紫红质2-2，尽管这不太可能显著改变最大吸收波长（lambdamax）位置。发现长波光敏感视蛋白P180是与长波光敏感视蛋白S180发生基因转换事件的产物，随后在180位点趋同于脯氨酸残基。
詹氏食蚊鱼至少有9种视觉视蛋白：三种长波光敏感视蛋白、一种视紫红质1、两种视紫红质2、一种短波敏感视蛋白1和两种短波敏感视蛋白2。长波光敏感视蛋白P180的存在将长波光敏感视蛋白P180 - S180串联重复事件的位置追溯到食蚊鱼科 - 四眼鱼科进化枝的基部，增加了拥有这种异常蓝移长波光敏感视蛋白的物种数量。长波光敏感视蛋白P180基因的存在也证实了基因转换事件使鱼类中的视蛋白旁系同源物同质化，就像在人类中一样。
