MOLECULAR EVOLUTION OF VISUAL PIGMENT GENES IN ASTYANAX

视觉对生物的进化有着深远的影响， 通过诸如择偶、觅食等基本行为来生存 策略和猎物偏好 它的重要性是由以下几点强烈表明的： 视觉色素存在于一系列生物体中， 细菌对人类 使用盲洞鱼和眼河鱼， characid，Astyanax fasciatus，我们建议调查模式 获得的核苷酸和氨基酸将有助于理解 功能适应和可能的视力退化。 通过构建基因组DNA文库、克隆和核苷酸测序， 利用聚合酶链反应（PCR）和直接测序， 计划对盲洞鱼和盲洞鱼的所有视觉色素基因进行表征， 有眼睛的河鱼 此外，我们将确定哪些视觉色素基因 都表现在河鱼的眼睛和 两种鱼。 这将使用cDNA的PCR扩增来实现 由这些器官的RNA制成，然后直接测序。 的DNA 获得的序列将用于评估以下生物学意义： 通过考虑统计数据，如（1） 过渡性和横断性变化，（2）核苷酸 替换，（3）同义和非同义变化的速率，以及（4） 密码子使用 这些数量将通过考虑不同 视色素的功能域，即，细胞内， 细胞外，和七个跨膜片段，并将用于 构建系统发育树，并估计不同的长度 树枝 核苷酸和氨基酸的起源、方向和速度 还将评估替代品。 此外，这些和其他 鸟嘌呤核苷酸结合蛋白偶联受体基因的序列将 可以用来对中性进化和适应性进化进行推理。

Vision has profound effects on the evolution of organisms by affecting survivorship through such basic behaviors as mating preference, foraging strategies and prey preference. Its importance is strongly indicated by the presence of visual pigments in a whole array of organisms ranging from bacteria to human. Using both blind cave fish and eyed river fish of the characid, Astyanax fasciatus, we propose to investigate the patterns of nucleotide and amino acid obtained will contribute in understanding functional adaptation and possible degeneration of vision. By constructing genomic DNA libraries, cloning and nucleotide sequencing and using the polymerase chain reaction (PCR) and direct sequencing, we plan to characterize all visual pigment genes from both blind cave fish and eyed river fish. In addition, we will determine which visual pigment genes are expressed in the eyes of the river fish and the pineal organs of the two types of fish. This will be achieved using PCR amplification of cDNA made from RNA of these organs followed by direct sequencing. The DNA sequences obtained will be used to evaluate the biological implications of the mutation accumulations by considering statistics such as (1) rates of transitional and transversional changes, (2) rates of nucleotide substitution, (3) rates of synonymous and nonsynonymous changes, and (4) codon usage. These quantities will be evaluated by considering different functional domains of the visual pigments, i.e., intracellular, extracellular, and seven transmembrane segments and will be used to construct phylogenetic trees and to estimate the lengths of the different branches. Origin, direction, and speed of nucleotide and amino acid substitutions will also be evaluated. Furthermore, these and other sequences of guanine nucleotide binding protein coupled receptor genes will be used to make inference on the neutral as well as adaptive evolutions.