促葡萄糖转运蛋白基因家族的分子进化研究

葡萄糖转运蛋白是一个在结构上相似功能上不同的多基因家族（ＧＬＵＴ１－ＧＬＵＴ５）。由于这一组蛋白和体内的葡萄糖利用有关,因此被认为是糖尿病胰岛素抵抗（抗性）的一个候选基因。本文比较了不同种生物这一基因家族的氨基酸和核苷酸顺序;推测了亲水性和疏水性分布;计算了蛋白质和核苷酸的进化距离,并在此基础上构建了分子进化树。研究表明：这一基因家族具有高度的同源性、极为相似的亲水性和疏水性分布以及结构的对称性。提示这一基因家族起源于一个共同的祖先并可能通过基因的重复而形成。这一进化机制可能有利于氨基酸结构的稳定及抵抗突变的作用。由于邻元法构建的进化树其分支长度存在差异,提示在这一基因家族的进化过程中,各分支上的进化速率并不相同。蛋白质进化距离和核苷酸进化距离所构建进化树的差异提示了在基因组中可能存在隐匿替换。两种方法构建的进化树都提示了ＧＬＵＴ１、３、４在结构和功能上要更为保守。     

木聚糖酶分子进化的研究进展

木聚糖的降解需要多种水解酶的协同作用,其中βD1,4内切木聚糖酶是最关键的水解酶之一。同一家族木聚糖酶氨基酸序列间有较高的同源性和较近的亲缘关系,这标准通常用于酶的家族归类。不同来源的同种木聚糖酶在相同位置上的氨基酸残基起源于共同祖先或者具有相似的生物学功能,而在进化过程中,对酶分子结构、催化起重要作用的氨基酸残基往往高度保守。综述了木聚糖酶分子进化的研究进展及其应用前景 。     

红树植物分子生态与进化研究进展

红树林是热带与亚热带海洋森林和地球湿地生态系统的重要组成部分 ,是多种海洋动物及鸟类栖息繁衍的重要场所 ,在调节全球生态平衡及维持生物多样性方面起着十分重要的作用。有关红树林的生态生物学研究 ,特别是红树林及其生物多样性变化的监测研究 ,红树林的保护与管理已成为热带亚热带海洋及湿地生态学研究的重要内容。海南岛有长达 1 5 2 8ｋｍ的海岸线 ,红树林群落的分布十分广泛。孢粉学证据说明 ,海南岛滨海地区在第三纪时即有红树林出现[1 ] 。现海南岛红树林植物种类有 1 8科 2 6属 34种 ,占中国红树植物种数的 97.1 % [2 ] 。由于…     

鸡IL-18成熟蛋白基因的克隆及分子进化分析

根据已发表的鸡白介素18(IL-18)基因序列设计合成引物,以植物凝集素(PHA)和脂多糖(LPS)激活的AA肉鸡脾细胞mRNA为模板,通过RT-PCR扩增出编码鸡IL-18成熟蛋白的eDNA。将该eDNA克隆于pUCm-T载体,并对其进行测序,结果表明所克隆的核苷酸片段包含了全部成熟蛋白编码基因,成熟蛋白编码区507个核苷酸,编码169个氧基酸。把该基因编码的鸡成熟IL-18蛋白氨基酸序列与已公布的禽及哺乳动物IL-8成熟蛋白基因氧基酸序列进行比较,其同源性分别在96．5％～100％和20．1％～26．6％之间,分子系统进化树分析表明鸡IL-18与哺乳动物IL-18有共同的祖先,亲源关系较近,但在免疫系统选择性压力下,形成独特的种族特异性。鸡IL-18基因的克隆为体外表达鸡IL-18蛋白及作为免疫佐剂应用于预防接种的研究奠定了基础。     

浙江省汉坦病毒基因分子进化分析

为了分析浙江省汉坦病毒分子流行病学的特点,本文应用分子生物学软件对1981～2007年从浙江省不同地区不同宿主分离的12株汉坦病毒的S、M基因序列进行分子进化分析,结果显示:浙江省属汉滩(HTN)型和汉城(SEO)型的混合型疫区,病毒的基因差异和亲缘远近关系主要表现在地区性,而与病毒分离的年代与宿主关系并不大,表现出明显的地理聚集现象,该现象在HTNV中的表现尤为明显,同一地区分离的病毒表现为较高的基因同源性,系统进化树上分布于同一或临近分支。另外发现分离自浙江省建德地区的Gou3和ZJ5株在SEOV进化枝中构成一独立分支,而且与国内外SEOV其他毒株的基因差异均较大,在浙江省建德地区存在着SOEV的特殊亚型病毒。     

八种纤毛虫减数分裂基因的分子进化研究

减数分裂是真核生物适应性进化的重要机制,以8种纤毛虫作为实验对象,通过生物信息学方法对其14个减数分裂基因进行了鉴定及分子进化研究。结果表明:(1)不同的纤毛虫种类存在一些特异性的减数分裂基因的丢失与复制现象;(2)减数分裂相关基因在纤毛虫中很保守;(3)纤毛虫减数分裂重要的同源重组过程是在真核生物中不常见的Ⅱ型。本研究表明,纤毛虫减数分裂可能代表了真核生物较原始的减数分裂方式,在进化的过程中很保守,为研究真核生物减数分裂起源与进化提供了重要线索。     

ras基因产物p^21的分子进化和癌变机理探讨

作者收集了人、果蝇、酵母、粘菌和病毒的10种P21氨基酸全顺序,运用AADIS和UPGMA两程序并结合进一步的数据分析揭示:①就协同进化来说,ras基因每年每基因平均重复率为2.78×10~(-9),这或许系迄今报道的最低速率保持者;②ras基因每年每氨基酸替代率为2.23×10~(-10),这在进化上是相当保守的。数据分析进一步证实的实验结果还有:①v-Has和v-Kis分别来自c-H-ras1和c-K-ras2;②c-H-ras1、c-K-ras2和c-N-ras由一个共同的祖先基因演化而来。根据Fitch等的观点,我们在此特别提出了p21的不变子/共变子转化假说,从分子进化角度对P21在癌变中的作用作出可能的解释。     

扬子鳄的CaSox4基因的分子克隆和进化分析

The completely identical HMG-box motif of CaSox4 gene from both male and female genomic DNA of the Chinese alligator (alligator sinensis) was cloned and sequenced by degenerate primer PCR.Compared with the human and mouse SRY,CaSox4 revealed 51% and 57% nucleotide homology respectively and 49% and 55% amino acid identity respectively,CaSox4 belongs to subgroup C of the Sox gene family.The GC content is 86% in the HMG-box region of the CaSox4 gene,Blast analysis showed that the CaSox4 gene shares 100^ amino acid identity with human Sox4.bird SoxLF4,turtle Sra4 and lizard CvSox4 genes.Casox4 may be orthologous with the human SOx4 gene.This indicates that CaSox4 gene shows the remarkable evolutionary conservation during the evolution of Alligator Sinensis,The extensive sequence conservation of the Sox4 gene between reptiles,mammals and birds suggests major functional constraints[Acta Zoologica Sinica 49(3):404-407,2003].     

文昌鱼转铁蛋白及转铁蛋白的分子进化

从厦门文昌鱼分离纯化了文昌鱼转铁蛋白,物化性质与青岛文昌鱼转铁蛋白相同,其单体和二聚体的分子量分别为２６ｋＤ和５２ｋＤ,是一分子量约为脊椎动物转铁蛋白１／４的糖蛋白,测定了文昌鱼转铁蛋白完整分子和其Ｃ端分子片段的部分氨基酸序列并分析 一人务清失蛋白氨基酸序列的同源性。发现用文昌鱼转铁蛋白序列可将人血清转铁蛋白序列划分成粗略相等的４个片段,文是鱼转铁蛋白与每一片段及人血清转铁蛋白的４个片段之间存在明     

Extraordinarily low evolutionary rates of short wavelength-sensitive opsin pseudogenes

Aquatic organisms such as cichlids, coelacanths, seals, and cetaceans are active in UV–blue color environments, but many of them mysteriously lost their abilities to detect these colors. The loss of these functions is a consequence of the pseudogenization of their short wavelength-sensitive (SWS1) opsin genes without gene duplication. We show that the SWS1 gene (Bden_S1ψ) of the deep-sea fish, pearleye (Benthalbella dentata), became a pseudogene in a similar fashion about 130 million years ago (Mya) yet it is still transcribed. The rates of nucleotide substitution (~ 1.4 × 10^− 9/site/year) of the pseudogenes of these aquatic species as well as some prosimian and bat species are much smaller than the previous estimates for the globin and immunoglobulin pseudogenes.     

Conserved cis-elements in the Xenopus red opsin promoter necessary for cone-specific expression

The long-wavelength sensitive (red) opsin genes encode proteins which play a central role in daytime and color vision in vertebrates. We used transgenic Xenopus to identify 5' cis-elements in the red cone opsin promoter necessary for cone-specific expression. We found a highly conserved extended region (-725 to -173) that was required for restricting GFP transgene expression to cones. We further identified a short element (5'-CCAATTAAGAGAT-3') highly conserved amongst tetrapods, including humans, necessary to restrict expression to cones in the retina. These results identify novel conserved elements that regulate spatial expression of tetrapod red cone opsin genes.     

Adaptive molecular evolution in the opsin genes of rapidly speciating cichlid species

Cichlid fish inhabit a diverse range of environments that vary in the spectral content of light available for vision. These differences should result in adaptive selective pressure on the genes involved in visual sensitivity, the opsin genes. This study examines the evidence for differential adaptive molecular evolution in East African cichlid opsin genes due to gross differences in environmental light conditions. First, we characterize the selective regime experienced by cichlid opsin genes using a likelihood ratio test format, comparing likelihood models with different constraints on the relative rates of amino acid substitution, across sites. Second, we compare turbid and clear lineages to determine if there is evidence of differences in relative rates of substitution. Third, we present evidence of functional diversification and its relationship to the photic environment among cichlid opsin genes. We report statistical evidence of positive selection in all cichlid opsin genes, except short wavelength-sensitive 1 and short wavelength-sensitive 2b. In all genes predicted to be under positive selection, except short wavelength-sensitive 2a, we find differences in selective pressure between turbid and clear lineages. Potential spectral tuning sites are variable among all cichlid opsin genes; however, patterns of substitution consistent with photic environment-driven evolution of opsin genes are observed only for short wavelength-sensitive 1 opsin genes. This study identifies a number of promising candidate-tuning sites for future study by site-directed mutagenesis. This work also begins to demonstrate the molecular evolutionary dynamics of cichlid visual sensitivity and its relationship to the photic environment.     

Constitutive activity of a UV cone opsin

Vertebrate visual pigment proteins contain a conserved carboxylic acid residue in the third transmembrane helix. In rhodopsin, Glu113 serves as a counterion to the positively charged protonated Schiff base formed by 11-cis retinal attached to Lys296. Activation involves breaking of this ion pair. In UV cone pigments, the retinyl Schiff base is unprotonated, and hence such a salt bridge is not present; yet the pigment is inactive in the dark. Mutation of Glu108, which corresponds to rhodopsin's Glu113, to Gln yields a pigment that remains inactive in the dark. The apoproteins of both the wild-type and mutant, however, are constitutively active with the mutant being of significantly higher activity. Thus, one important role for preserving the negatively charged glutamate in the third helix of UV pigments is to maintain a less active opsin in a manner similar to rhodopsin. Ligand binding itself in the absence of a salt bridge is sufficient for deactivation.     

The molecular evolution of the vertebrate behavioural repertoire

How the sophisticated vertebrate behavioural repertoire evolved remains a major question in biology. The behavioural repertoire encompasses the set of individual behavioural components that an organism uses when adapting and responding to changes in its external world. Although unicellular organisms, invertebrates and vertebrates share simple reflex responses, the fundamental mechanisms that resulted in the complexity and sophistication that is characteristic of vertebrate behaviours have only recently been examined. A series of behavioural genetic experiments in mice and humans support a theory that posited the importance of synapse proteome expansion in generating complexity in the behavioural repertoire. Genome duplication events, approximately 550 Ma, produced expansion in the synapse proteome that resulted in increased complexity in synapse signalling mechanisms that regulate components of the behavioural repertoire. The experiments demonstrate the importance to behaviour of the gene duplication events, the diversification of paralogues and sequence constraint. They also confirm the significance of comparative proteomic and genomic studies that identified the molecular origins of synapses in unicellular eukaryotes and the vertebrate expansion in proteome complexity. These molecular mechanisms have general importance for understanding the repertoire of behaviours in different species and for human behavioural disorders arising from synapse gene mutations.     

Contrasting modes of evolution between vertebrate sweet/umami receptor genes and bitter receptor genes

Taste reception is fundamental to diet selection in many animals. The genetic basis underlying the evolution and diversity of taste reception, however, is not well understood. Recent discoveries of T1R sweet/umami receptor genes and T2R bitter receptor genes in humans and mice provided an opportunity to address this question. Here, we report the identification of 20 putatively functional T1R genes and 167 T2R genes from the genome sequences of nine vertebrates, including three fishes, one amphibian, one bird, and four mammals. Our comparative genomic analysis shows that orthologous T1R sequences are relatively conserved in evolution and that the T1R gene repertoire remains virtually constant in size across most vertebrates, except for the loss of the T1R2 sweet receptor gene in the sweet-insensitive chicken and the absence of all T1R genes in the tongueless western clawed frog. In contrast, orthologous T2R sequences are more variable, and the T2R repertoire diverges tremendously among species, from only three functional genes in the chicken to 49 in the frog. These evolutionary patterns suggest the relative constancy in the number and type of sweet and umami tastants encountered by various vertebrates or low binding specificities of T1Rs but a large variation in the number and type of bitter compounds detected by different species. Although the rate of gene duplication is much lower in T1Rs than in T2Rs, signals of positive selection are detected during the functional divergences of paralogous T1Rs, as was previously found among paralogous T2Rs. Thus, functional divergence and specialization of taste receptors generally occurred via adaptive evolution.     

Mechanisms of spectral tuning in the RH2 pigments of Tokay gecko and American chameleon

At present, molecular bases of spectral tuning in rhodopsin-like (RH2) pigments are not well understood. Here, we have constructed the RH2 pigments of nocturnal Tokay gecko (Gekko gekko) and diurnal American chameleon (Anolis carolinensis) as well as chimeras between them. The RH2 pigments of the gecko and chameleon reconstituted with 11-cis-retinal had the wavelengths of maximal absorption (lambda(max)'s) of 467 and 496 nm, respectively. Chimeric pigment analyses indicated that 76-86%, 14-24%, and 10% of the spectral difference between them could be explained by amino acid differences in transmembrane (TM) helices I-IV, V-VII, and amino acid interactions between the two segments, respectively. Evolutionary and mutagenesis analyses revealed that the lambda(max)'s of the gecko and chameleon pigments diverged from each other not only by S49A (serine to alanine replacement at residue 49), S49F (serine to phenylalanine), L52M (leucine to methionine), D83N (aspartic acid to asparagine), M86T (methionine to threonine), and T97A (threonine to alanine) but also by other amino acid replacements that cause minor lambda(max)-shifts individually.     

与线粒体分裂有关的蛋白质研究进展

在活细胞内线粒体处于不断的融合与分裂状态,线粒体融合与分裂的动态平衡影响着线粒体的形态和数量,本文对近年来与线粒体分裂有关的蛋白质研究进行了综述：（1）酵母（S.cerevisae)中的Dnm1蛋白或它的同源蛋白质可能通过缠绕于线粒体的收缩部分而影响线粒体外膜分裂;（2）位于线粒体上的3种同源蛋白Mdv1/Fis2/Gag3与Dnm1能短暂结合,它们都是线粒体分裂装置的组成部分;（3）一个插入线粒体外膜的跨膜蛋白Fisl或Mdv2极有可能是线粒体分裂装置的招募因子,并且由它启动分裂过程;（4）分布于膜间隙（IMS）中的Mgm1蛋白并不负责线粒体内膜分裂,这与以前的观点相反。