中国和韩国黑线姬鼠两亚种的线粒体DNA限制性片段分析

本文利用印迹杂交技术对中国华北地区黑线姬鼠Ａｐｏｄｅｍｕｓａｇｒａｒｉｕｓｐａｌｉｄｉｏｒ和韩国黑线姬鼠Ａ．ａｇｒａｒｉｕｓｃｏｒｅａｅ共１０７号标本的线粒体ＤＮＡ（ｍｉｔｏｃｈｏｎｄｒｉａｌＤＮＡ,ｍｔＤ－ＮＡ）,通过８种限制性内切酶的消化,进行了限制性片段的分析。共检出３５种限制性片段和１２种单倍体类型。１２种单倍型在平均离散度为１．０１％时聚合为两个亚群：一个亚群为黑线姬鼠华北亚种,由采自中国４个不同地区的５１号标本的４种单倍型所组成;另一个亚群为黑线姬鼠朝鲜亚种,由采自韩国４个不同地区的５６号标本的８种单倍型所组成。黑线姬鼠华北亚种和朝鲜亚种在ｍｔＤＮＡ表型上表现出一定差异,这在分子水平上确立了两亚种的分类地位。为了进一步澄清黑线姬鼠种下分类的混乱,很有必要对中国其他地区的标本进行该项研究     

Molecular evolution of a portion of the mitochondrial 16S ribosomal gene region in scleractinian corals

Relationships among families and suborders of scleractinian corals are poorly understood because of difficulties 1) in making inferences about the evolution of the morphological characters used in coral taxonomy and 2) in interpreting their 240-million-year fossil record. Here we describe patterns of molecular evolution in a segment of the mitochondrial (mt) 16S ribosomal gene from taxa of 14 families of corals and the use of this gene segment in a phylogenetic analysis of relationships within the order. We show that sequences obtained from scleractinians are homologous to other metazoan 16S ribosomal sequences and fall into two distinct clades defined by size of the amplified gene product. Comparisons of sequences from the two clades demonstrate that both sets of sequences are evolving under similar evolutionary constraints: they do not differ in nucleotide composition, numbers of transition and transversion substitutions, spatial patterns of substitutions, or in rates of divergence. The characteristics and patterns observed in these sequences as well as the secondary structures, are similar to those observed in mt 16S ribosomal DNA sequences from other taxa. Phylogenetic analysis of these sequences shows that they are useful for evaluating relationships within the order. The hypothesis generated from this analysis differs from traditional hypotheses for evolutionary relationships among the Scleractinia and suggests that a reevaluation of evolutionary affinities in the order is needed. Received: 4 September 1996 / Accepted: 7 April 1997     

Inactivation of the Peptide-Sensitive Channel from the Yeast Mitochondrial Outer Membrane: Properties,Sensitivity to Trypsin and Modulation by a Basic Peptide

The yeast Peptide Sensitive Channel (PSC), a cationic channel of the mitochondrial outer membrane closes with slow kinetics at potentials of either polarity. The properties of this inactivation closely resemble those of the Voltage-Dependent Anion Channel (VDAC) slow kinetics closures. Addition of trypsin to one compartment suppresses the inactivation observed when this compartment is made positive, but does not affect the inactivation observed at potentials of reverse polarity. Both sides of the channel are sensitive. The reduced form of the Mast Cell Degranulating peptide (rMCD) increases the rate of inactivation, but only when the polarity of the compartment to which it is added is positive. The effect is not reversed by washing the peptide out, but is suppressed by trypsin. The peptide can bind to both sides of the membrane. The effect of rMCD on PSC closely resembles that of the ``modulator' on VDAC. The similarities between PSC and VDAC suggest that the former might be a cationic porin of the mitochondrial outer membrane possessing a structure closely related to that of VDAC. Received: 2 February 1996/Revised: 18 October 1996     

Evolution of the mitochondrial DNA control region in the mbuna (Cichlidae) species flock of lake Malawi, East Africa

Considerable controversy has surrounded the application of mitochondrial DNA data to reconstruction of evolutionary relationships among the endemic cichlids of Lake Malawi. Central to this debate has been the issue of whether lineage sorting is complete, and thus whether these data actually reflect species phylogeny, or simply gene genealogy. Review of all mtDNA control region sequences available for members of one monophyletic subset of this species flock, the Malawi rockfishes, or mbuna, strongly indicates that lineage sorting is incomplete: Character-based analyses of these sequences reconstruct gene, not species, interrelationships. Analysis of the pattern of nucleotide substitutions differentiating these mtDNA alleles suggests that pyrimidine residues undergo transition substitutions more often than do purines. Estimation of the magnitude of derived sequence differentiation in light of the reconstructed gene genealogy suggests that the mbuna may be of considerably more recent vintage than previous molecular characterizations have indicated. Received: 6 April 1996 / Accepted: 3 March 1997     

Nucleotide Composition Bias Affects Amino Acid Content in Proteins Coded by Animal Mitochondria

We show that in animal mitochondria homologous genes that differ in guanine plus cytosine (G + C) content code for proteins differing in amino acid content in a manner that relates to the G + C content of the codons. DNA sequences were analyzed using square plots, a new method that combines graphical visualization and statistical analysis of compositional differences in both DNA and protein. Square plots divide codons into four groups based on first and second position A + T (adenine plus thymine) and G + C content and indicate differences in amino acid content when comparing sequences that differ in G + C content. When sequences are compared using these plots, the amino acid content is shown to correlate with the nucleotide bias of the genes. This amino acid effect is shown in all protein-coding genes in the mitochondrial genome, including cox I, cox II, and cyt b, mitochondrial genes which are commonly used for phylogenetic studies. Furthermore, nucleotide content differences are shown to affect the content of all amino acids with A + T- and G + C-rich codons. We speculate that phylogenetic analysis of genes so affected may tend erroneously to indicate relatedness (or lack thereof) based only on amino acid content. Received: 3 July 1996 / Accepted: 6 November 1996     

金丝猴属的DNA序列变异及进化与保护遗传学研究

金丝猴的分类及系统发育存在许多争议。本文测定了２只川金丝猴、８只滇金丝猴、１只越南金丝猴和１只灰叶猴的２５３ｂｐ的线粒体细胞色素ｂ基因的序列。其中４７个位点（１９％）检出变异。我们采用简约法、最大似然法和距离法构建了一系列的分子系统树,得到相同的拓扑结构,从而可能在分子水平澄清了金丝猴属的系统发育。结果表明,云南金丝猴与越南金丝猴间的关系较与川金丝猴的为近。金丝猴属的分化大约发生在２～６百万年以前。这３种金丝猴均是独立的种,且都应归入金丝猴属。对８只来自野外的滇金丝猴（其中包括了昆明动物研究所圈养群体的所有６只创立者）的非损伤性遗传分析提示,编号为ＹＫ２的母猴是维持该圈养群体遗传多样性的关键猴。我们建立的这种非损伤性遗传分析方法广泛适用于珍稀濒危动物的遗传多样性及遗传管理研究。     

水稻线粒体DNA雄性不育有关特异片段的克隆及序列分析

应用任意单引物聚合酶链反应技术,从水稻ＷＡ 型雄性不育系的线粒体ＤＮＡ 中得到一个特异的扩增片段Ｒ２－６３０ ＷＡ。以该片段为探针进行Ｓｏｕｔｈｅｒｎ 杂交分析检测到在雄性不育胞质与正常可育胞质间存在的线粒体ＤＮＡ 多态性。不育系珍汕９７Ａ 和其Ｆ１ 杂种的杂交图谱相同。而保持系珍汕９７Ｂ和恢复系明恢６３ 的杂交图谱一样。序列测定该片段全长６２９ ｂｐ,其碱基组成Ａ＋ Ｔ＝ ５４．１％ ,同源性比较结果显示, 该片段与１２３６ 个已报道的植物基因（包括１６ 个水稻线粒体基因）序列的同源性均小于５０％ 。序列内含有一个长度为１０ ｂｐ 的反向重复序列５－ＡＣＣＡＴＡＴＧＧＴ－３,位于２６２—２７２ 区段。另外,其３７９—４３９ 区段可编码一个含２０个氨基酸残基的短肽。上述结果表明,Ｒ２－６３０ ＷＡ 片段确与水稻野败型雄性不育密切相关。推测反向重复序列５－ＡＣＣＡＴＡＴＧＧＴ－３在细胞质雄性不育性状形成中,可能起着重要作用     

Phylogenetic relationships of someMicrosporum andArthroderma species inferred from mitochondrial DNA analysis

Thirty-eight strains of 12Microsporum and 10Arthroderma (Nannizzia) species were investigated by analysis of mitochondrial DNA with 6 restriction enzymes, and classified into 13 genetic groups. The phylogenetic tree of the 13 groups thus established was constructed. On the tree,M. audouinii, M. langeronii, M. rivalieri, M. distortum, M. equinum, M. ferrugineum andA. otae comprise one genetic group and are suggested to be the same species.A. gypseum, A. fulvum, M. duboisii, M. ripariae, A. incurvatum, A. persicolor andA. obtusum are clustered on one of five boughs of the tree indicating their close relation.A. racemosum andA. cajetani are also closely related.     

Intracellular heteroplasmy for disease-associated point mutations in mtDNA: implications for disease expression and evidence for mitotic segregation of heteroplasmic units of mtDNA

Studies in vitro have shown that a respiratorydeficient phenotype is expressed by cells when the proportion of mtDNA with a disease-associated mutation exceeds a threshold level, but analysis of tissues from patients with mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) have failed to show a consistent relationship between the degree of heteroplasmy and biochemical expression of the defect. One possible explanation for this phenomenon is that there is variation of heteroplasmy between individual cells that is not adequately reflected by the mean heteroplasmy for a tissue. We have confirmed this by study of fibroblast clones from subjects heteroplasmic for the MELAS 3243 (A G) mtDNA mutation. Similar observations were made with fibroblast clones derived from two subjects heteroplasmic for the 11778 (GA) mtDNA mutation of Leber's hereditary optic neuropathy. For the MELAS 3243 mutation, the distribution of mutant mtDNA between different cells was not randomly distributed about the mean, suggesting that selection against cells with high proportions of mutant mtDNA had occurred. To explore the way in which heteroplasmic mtDNA segregates in mitosis we followed the distribution of heteroplasmy between clones over approximately 15 generations. There was either no change or a decrease in the variance of intercellular heteroplasmy for the MELAS 3243 mutation, which is most consistent with segregation of heteroplasmic units of multiple mtDNA molecules in mitosis. After mitochondria from one of the MELAS 3243 fibroblast cultures were transferred to a mitochondrial DNA-free (⁰) cell line derived from osteosarcoma cells by cytoplast fusion, the mean level and intercellular distribution of heteroplasmy was unchanged. We interpret this as evidence that somatic segregation (rather than nuclear background or cell differentiation state) is the primary determinant of the level of heteroplasmy.     

Evidence that the crystalline arrays in the outer membrane of Neurospora mitochondria are composed of the voltage-dependent channel protein

Antibodies were raised in rabbits against the outer membrane of Neurospora mitochondria. Antibodies were obtained that were specific for this membrane's major polypeptide ($\text{M, 31 000}$) and its slower-migrating derivatives on SDS-polyacrylamide gels. These antibodies inhibited the insertion into phospholipid bilayers of voltage-dependent ion channels from detergent extracts of the mitochondrial outer membranes. The same antibodies bound preferentially to membranes containing crystalline surface arrays in outer mitochondrial membrane fractions. These results indicate that the 31 kDa polypeptide is a component both of the ion channels and of the membrane arrays, suggesting identity between the functional and structural entities.