来自两种有袋动物的视杆视蛋白色素，即南美裸尾袋貂和澳大利亚肥尾袋鼩。

The rod opsin pigments from two marsupial species, the South American bare-tailed woolly opossum and the Australian fat-tailed dunnart.

作者信息

Hunt David M, Arrese Catherine A, von Dornum Miranda, Rodger Jenny, Oddy Alison, Cowing Jill A, Ager Eleanor I, Bowmaker James K, Beazley Lyn D, Shand Julia

机构信息

Division of Molecular Genetics, Institute of Ophthalmology, University College London, Bath Street, EC1V 9EL, London, UK.

出版信息

Gene. 2003 Dec 24;323:157-62. doi: 10.1016/j.gene.2003.09.016.

DOI:10.1016/j.gene.2003.09.016

PMID:14659889

Abstract

Rod visual pigment genes have been studied in a wide range of vertebrates including a number of mammalian species. However, no marsupials have yet been examined. To correct this omission, we have studied the rod pigments in two marsupial species, the nocturnal and frugivorous bare-tailed woolly opossum, Caluromys philander, from Central and South America, and the arhythmic and insectivorous fat-tailed dunnart, Sminthopsis crassicaudata, from Australia. Phylogenetic analysis establishes that the cloned opsin sequences are orthologues of rod opsin genes from other vertebrate species. The deduced amino acid sequences show that both possess glutamate at residue 122, a feature of rod opsins, and the corresponding gene follows the typical vertebrate rod opsin pattern of five exons separated by four introns. Compared to other vertebrates, a stretch of five residues near the C-terminus is deleted in the rod opsin of both marsupials and all eutherian mammals. From microspectrophotometric measurements, the pigments in the two species show an 8 nm difference in peak absorbance; the molecular basis for this spectral shift is discussed and two candidate substitutions are identified.

摘要

视杆视觉色素基因已在包括许多哺乳动物物种在内的广泛脊椎动物中进行了研究。然而，尚未对有袋动物进行过研究。为了纠正这一疏漏，我们研究了两种有袋动物的视杆色素，一种是来自中南美洲的夜行性食果动物裸尾袋鼹（Caluromys philander），另一种是来自澳大利亚的无节律食虫动物肥尾袋鼬（Sminthopsis crassicaudata）。系统发育分析表明，克隆的视蛋白序列是其他脊椎动物物种视杆视蛋白基因的直系同源物。推导的氨基酸序列显示，两者在第122位残基处均具有谷氨酸，这是视杆视蛋白的一个特征，并且相应的基因遵循典型的脊椎动物视杆视蛋白模式，即由四个内含子分隔的五个外显子。与其他脊椎动物相比，两种有袋动物和所有真兽类哺乳动物的视杆视蛋白在C末端附近都缺失了一段五个残基的序列。通过显微分光光度测量，这两个物种的色素在峰值吸光度上有8纳米的差异；讨论了这种光谱 shift 的分子基础，并确定了两个候选替代物。