African,Native American,and European mitochondrial DNAs in Cubans from Pinar del Rio Province and implications for the recent epidemic neuropathy in Cuba

Genetic predisposition, particularly specific mitochondrial DNA (mtDNA) backgrounds, has been proposed as a contributing factor in the expression of an epidemic of bilateral optic neuropathy that has affected residents of Cuba since 1991. To substantiate or refute the possibility that specific subsets of mtDNAs could participate in disease expression, we took advantage of the heterogeneous ethnic origin of the Cuban population and the recent identification of a number of mtDNA polymorphisms that appear to be specific for Africans, Native Americans, and Europeans. The screening of both carefully selected people with epidemic neuropathy and control subjects from the Pinar del Rio Province for these polymorphisms revealed that African, Native American, and European mtDNA haplotypes were equally represented among case and control subjects, and suggested that ～ 50% of Cuban mtDNAs originated from Europeans, 46% from Africans, and 4% from Native Americans. These findings demonstrate that mutations arising in spic mtDNAs are unlikely to play a role in the epidemic neuropathy and indicate that analysis of mtDNA haplotypes can be a valuable tool for assessing the relative maternal contribution of Africans, Native Americans, and Europeans in a mixed population. © 1995 Wiley-Liss, Inc.     

Nucleotide base sequence of the mitochondrial COIII gene of Schizophyllum commune

Summary The cytochrome oxidase subunit III gene (COIII) of the Badidiomycete S. commune has been identified, cloned, and sequenced. The gene contains no introns, is AT-rich (69%) and exhibits a high degree of similarity to sequences from Ascomycetes. While most mitochondrial genes use both TGA and TGG to specify tryptophan, the COIII gene of Schizophyllum uses TGG exclusively. Translation requires no deviation from the universal code.     

Presence of a linear plasmid-like DNA molecule in the fungal pathogen Ceratocystis fimbriata Ell. & Halst.

Summary A plasmid-like molecule was detected in a strain of the ascomycete Ceratocystis fimbriata Ell. & Halst., a pathogenic fungus of Populus spp. The DNA replicon, designated pFQ501, was found to have a linear structure with a length of 6.0 kb (3.9 × 10⁶ daltons) and a density of 1.685 g/cc. This molecule was found to be associated with the mitochondria and was isolated from the gel; its restriction map was deduced from single and double digestions.     

De novo COX2 mutation in a LHON family of Caucasian origin: implication for the role of mtDNA polymorphism in human pathology

Recent studies suggest that certain mutations with phylogeographic importance as haplogroup markers may also influence the phenotypic expression of particular mitochondrial disorders. One such disorder, Lebers hereditary optic neuropathy (LHON), demonstrates a clear expression bias in mtDNAs belonging to haplogroup J, a West Eurasian maternal lineage defined by polymorphic markers that have been called secondary disease mutations. In this report, we present evidence for a de novo heteroplasmic COX2 mutation associated with a LHON clinical phenotype. This particular mutation—at nucleotide position 7,598—occurs in West Eurasian haplogroup H, the most common maternal lineage among individuals of European descent, whereas previous studies have detected this mutation only in East Eurasian haplogroup E. A review of the available mtDNA sequence data indicates that the COX2 7598 mutation occurs as a homoplasic event at the tips of these phylogenetic branches, suggesting that it could be a variant that is rapidly eliminated by selection. This finding points to the potential background influence of polymorphisms on the expression of mild deleterious mutations such as LHON mtDNA defects and further highlights the difficulties in distinguishing deleterious mtDNA changes from neutral polymorphisms and their significance in the development of mitochondriopathies.     

Mitochondrial DNA and Y-Chromosome Variation in the Caucasus

We have analyzed mtDNA HVI sequences and Y chromosome haplogroups based on 11 binary markers in 371 individuals, from 11 populations in the Caucasus and the neighbouring countries of Turkey and Iran. Y chromosome haplogroup diversity in the Caucasus was almost as high as in Central Asia and the Near East, and significantly higher than in Europe. More than 27% of the variance in Y‐haplogroups can be attributed to differences between populations, whereas mtDNA showed much lower heterogeneity between populations (less then 5%), suggesting a strong influence of patrilocal social structure. Several groups from the highland region of the Caucasus exhibited low diversity and high differentiation for either or both genetic systems, reflecting enhanced genetic drift in these small, isolated populations. Overall, the Caucasus groups showed greater similarity with West Asian than with European groups for both genetic systems, although this similarity was much more pronounced for the Y chromosome than for mtDNA, suggesting that male‐mediated migrations from West Asia have influenced the genetic structure of Caucasus populations.     

Y Chromosome and Mitochondrial DNA Characterization of Pasiegos, a Human Isolate from Cantabria (Spain)

Mitochondrial DNA sequences and Y chromosome haplotypes were characterized in Pasiegos, a human isolate from Cantabria, and compared with those of other Cantabrian and neighbouring Northern Spain populations. Cantabria appears to be a genetically heterogeneous community. Whereas Lebaniegos do not differ from their eastern Basque and western Asturian and Galician neighbours, Pasiegos and other non‐Lebaniego Cantabrians show significant differences with all of them. Pasiegos are peculiar for their high frequencies of Y chromosomal markers (E‐M81) with North African assignation, and Y chromosomal (R‐SRY2627) and mtDNA (V, I, U5) markers related to northern European populations. This dual geographic contribution is more in agreement with the complex demographic history of this isolate, as opposed to recent drift effects. The high incidence in Cantabrians with pre‐V and V mtDNA haplotypes, considered as a signal of Postglacial recolonization in Europe from south‐western refugees, points to such refugees as a better candidate population than Basques for this expansion. However, this does not discount a conjoint recolonization.     

裂褶菌胞外多糖对D-半乳糖致衰老小鼠学习记忆及代谢产物的影响

目的研究裂褶菌(Schizophyllum commne Fr)胞外多糖(SPG)对D-半乳糖致衰老小鼠各项指标的影响。方法建立D-半乳糖衰老小鼠模型,以其学习记忆成绩,免疫器官指数,血清、肝、脑中超氧化物歧化酶(SOD)活力、丙二醛(MDA)含量,脑中单胺氧化酶(MAO)活力,肝、脑细胞线粒体DNA含量为指标,对SPG的抗衰老作用进行研究。结果与模型组比较,SPG可恢复D-半乳糖致衰老小鼠的学习记忆能力;拮抗免疫器官萎缩;提高其血清、肝和脑中SOD活性;减少MDA在体内积累;抑制脑中MAO活性;降低肝、脑细胞线粒体DNA相对含量。最适剂量为200 mg.kg-1。结论高剂量SPG具有明显抗衰老作用(P<0.01),且具有靶向性,对血清和肝组织的抗衰老作用较强,对大脑的改善作用不如前者。     

DNA条形码技术在福建省蝇类鉴定中的应用

目的探讨DNA条形码技术应用于福建省蝇类鉴定的可行性,并初步建立福建省蝇类的基因数据库。方法采集自福建省部分地区的4科13属19种64个蝇类新鲜标本,提取基因组DNA进行PCR扩增,序列测序,并进行同源性对比、进化距离分析,构建系统进化树。结果基因序列分析结果显示,上述蝇类mt DNA上细胞色素C氧化酶亚基Ⅰ基因序列的种内进化分歧均数在0～3.32%之间;除铜绿蝇与丝光绿蝇进化分歧均数为0.69%外,其余种间进化分歧均数在5.26%～18.30%之间;系统进化树分析显示,相同种能够很好聚集在一起,Bootstrap检验可信度均达96%以上。结论DNA条形码技术可用于福建省一些常见蝇类的鉴定,作为形态学鉴定的补充手段。     

畲族人群遗传性非综合征性常见耳聋基因突变谱的筛查

目的：筛查分析福建畲族常见耳聋基因突变在不同听力表型人群中的携带分布情况,以探讨畲族耳聋患者基因突变的特点。方法：通过耳鼻喉科专科检查和听力检测,选取150例先证者接受多项常见耳聋基因检测,包括SLC26A4编码区测序、GJB2编码区测序和mtDNAc1494T／A1555G突变基因芯片检测。其中,双耳感音神经性聋102例,单耳感音神经性聋18例,有耳聋家族史但听阈正常者30例。结果：150例受检者的SLC26A4基因、GJB2基因、mtDNAA1555G／C1494T突变检出率分别为3．3％、6％、2％、0．7％。结论：畲族听损患者中GJB2基因突变阳性检出率较高,应重视对新生儿的常规耳聋基因的筛查和诊断。