血耳及其宿主菌的分离与系统发育分析

为研究血耳(Tremella sanguinea Y.B.Peng)及其宿主菌的分类地位,利用担孢子弹射法和耳木组织培养法从椴木栽培的血耳中分离得到1株酵母状菌株XE01和1株丝状真菌菌株XE02,分别对这两株菌株进行了菌落形态和显微形态观察及基于rDNA-ITS序列的系统发育分析.结果显示,XE01在PDA培养基上形...     

荞麦不同种间BW10KD过敏蛋白基因序列比较

荞麦过敏蛋白(BW10KD)与变应原病人的血清免疫球蛋白(immunoglobulin E,IgE)有强烈反应.通过对属于8个养麦种和1个变种的58个收集系中的BW10KD过敏蛋白基因保守片段进行差异分析与系统进化关系研究,为探讨BW10KD基因的结构功能及其在不同种间的进化奠定了基础,并为发生在物种基因DNA水平的微尺度的变异与进化研究中提供新的分析方法.用设计的特异引物进行扩增,所得序列与已报道过敏蛋白编码基因序列相似性达99％.各收集系间进行序列比对,得到307个排列位点(不含缺失位点),其中单型不变位点150个,多态位点S为157个(含简约信息位点数101个和单型可变位点56个).整个序列突变位点Eta为201个.选择特定分类群内变异小、分类群间变异大的19个位点进行系统聚类分析得到清晰的种系关系图.金荞、细柄野荞、硬枝万年荞聚在一起,暗示其具有较保守的BW10KD过敏蛋白基因序列;栽培甜荞与野甜荞亲缘关系近,其次与左贡野荞较近缘;毛野荞与大野荞彼此较近缘;栽培苦荞与野苦荞亲缘关系最近,与毛野荞和大野荞亲缘关系次之.     

Genetic variation among spiny-footed lizards in the Acanthodactylus pardalis group from North Africa

The systematics of the genus Acanthodactylus was classically based on external morphological traits, osteological characters and morphology of the hemipenes. Although the identification of species complexes is relatively easy, the distinction within some groups is difficult due to a high variability of the external morphology. Partial mitochondrial (12S and 16S rRNA) sequences (371 and 499 base pairs, respectively) were analysed from 32 specimens of the A. pardalis group from northern Africa including the described species A. busacki, A. maculatus, A. mechriguensis and A. pardalis. Several highly distinct genetic units were resolved, but with little support for relationships between them. These units did not coincide with current taxonomic units, but showed geographic structuring. Although the A. pardalis group displays significant variation, the present taxonomy of the group must be considered unsatisfactory since it is not supported by genetic evidence. For some forms, such as A. mechriguensis there is no support and it is suggested that it should be synonymized with A. maculatus. More data are clearly needed for other forms. Complex microevolutionary patterns due to the recent contraction/ expansion phases of the Sahara Desert probably are related with the phylogenetic patterns observed.     

A class-wide phylogenetic assessment of Dothideomycetes

We present a comprehensive phylogeny derived from 5 genes, nucSSU, nucLSU rDNA, TEF1, RPB1 and RPB2, for 356 isolates and 41 families (six newly described in this volume) in Dothideomycetes. All currently accepted orders in the class are represented for the first time in addition to numerous previously unplaced lineages. Subclass Pleosporomycetidae is expanded to include the aquatic order Jahnulales. An ancestral reconstruction of basic nutritional modes supports numerous transitions from saprobic life histories to plant associated and lichenised modes and a transition from terrestrial to aquatic habitats are confirmed. Finally, a genomic comparison of 6 dothideomycete genomes with other fungi finds a high level of unique protein associated with the class, supporting its delineation as a separate taxon.     

Evolution of CDC42, a putative virulence factor triggering meristematic growth in black yeasts

The cell division cycle gene (CDC42) controlling cellular polarization was studied in members of Chaetothyriales. Based on ribosomal genes, ancestral members of the order exhibit meristematic growth in view of their colonization of inert surfaces such as rock, whereas in derived members of the order the gene is a putative virulence factor involved in expression of the muriform cell, the invasive phase in human chromoblastomycosis. Specific primers were developed to amplify a portion of the gene of 32 members of the order with known position according to ribosomal phylogeny. Phylogeny of CDC42 proved to be very different. In all members of Chaetohyriales the protein sequence is highly conserved. In most species, distributed all over the phylogenetic tree, introns and 3^rd codon positions are also invariant. However, a number of species had paralogues with considerable deviation in non-coding exon positions, and synchronous variation in introns, although non-synonomous variation had remained very limited. In some strains both orthologues and paralogues were present. It is concluded that CDC42 does not show any orthologous evolution, and that its paralogues haves the same function but are structurally relaxed. The variation or absence thereof could not be linked to ecological changes, from rock-inhabiting to pathogenic life style. It is concluded that eventual pathogenicity in Chaetothyriales is not expressed at the DNA level in CDC42 evolution.     

A rock-inhabiting ancestor for mutualistic and pathogen-rich fungal lineages

Rock surfaces are unique terrestrial habitats in which rapid changes in the intensity of radiation, temperature, water supply and nutrient availability challenge the survival of microbes. A specialised, but diverse group of free-living, melanised fungi are amongst the persistent settlers of bare rocks. Multigene phylogenetic analyses were used to study relationships of ascomycetes from a variety of substrates, with a dataset including a broad sampling of rock dwellers from different geographical locations. Rock-inhabiting fungi appear particularly diverse in the early diverging lineages of the orders Chaetothyriales and Verrucariales. Although these orders share a most recent common ancestor, their lifestyles are strikingly different. Verrucariales are mostly lichen-forming fungi, while Chaetothyriales, by contrast, are best known as opportunistic pathogens of vertebrates (e.g. Cladophialophora bantiana and Exophiala dermatitidis, both agents of fatal brain infections) and saprophytes. The rock-dwelling habit is shown here to be key to the evolution of these two ecologically disparate orders. The most recent common ancestor of Verrucariales and Chaetothyriales is reconstructed as a non-lichenised rock-inhabitant. Ancestral state reconstructions suggest Verrucariales as one of the independent ascomycetes group where lichenisation has evolved on a hostile rock surface that might have favored this shift to a symbiotic lifestyle. Rock-inhabiting fungi are also ancestral to opportunistic pathogens, as they are found in the early diverging lineages of Chaetothyriales. In Chaetothyriales and Verrucariales, specific morphological and physiological traits (here referred to as extremotolerance) evolved in response to stresses in extreme conditions prevailing on rock surfaces. These factors facilitated colonisation of various substrates including the brains of vertebrates by opportunistic fungal pathogens, as well as helped establishment of a stable lichen symbiosis.     

金丝猴生态学和分子生物学研究进展

金丝猴(Rhinopithecus)是典型的经历快速辐射和近期物种形成事件的进化类群,分为川金丝猴(Rhinopithecus roxellanae)、黔金丝猴(Rhinopithecus brelichi)、滇金丝猴(Rhinopithecus bieti)、越南金丝猴(Rhinopithecus avunculus)和缅甸金丝猴(Rhinopithecus strykeri)5个种。它们共同占据着东南亚的森林和林地生态位,是非人灵长类重要物种,国内外学者在它们的宏观和微观方面都做了大量研究工作,文章就5种金丝猴各自的生态学和分子生物学研究现状进行综述,并对存在的问题提出相应的建议。     

黄瓜NRT3基因的鉴定和特征分析

旨在探讨黄瓜NRT3基因的遗传进化和功能,为进一步研究黄瓜NRT3基因的功能提供依据。利用生物信息学方法,从黄瓜基因组中鉴定出2个NRT3基因,并对这些基因的基因组分布、结构、遗传进化和顺式元件进行了系统分析。结果显示,黄瓜的NRT3两个基因均位于1号染色体,具有1个或者2个外显子,分别与拟南芥的NRT3.1或者NRT3.2直系同源。NRT3在瓜类作物间编码蛋白的序列非常保守,它们都具有数个植物激素和逆境应答元件,而且黄瓜和甜瓜的直系同源NRT3基因的顺式调控元件存在较大差异。本研究为进一步研究黄瓜NRT3的遗传进化和功能提供了线索。     

基于S7核糖体蛋白基因部分序列的7种金线鱼属鱼类分子系统进化关系

测定了7种金线鱼属(Nemipterus)及2种锥齿鲷属(Pentapus)鱼类S7核糖体蛋白基因(S7基因)内含子1部分序列,以二线眶棘鲈(Scolopsis bilineatus)做为外类群初步探讨了其分子进化关系.测序所得S7部分序列为734~746 bp,序列比对后得到同源序列743 bp.其中保守位点386个,变异位点351个,简约性信息位点289个.A+T含量(54.1%)高于G+C含量(45.9%).基于Kimura 2-Parameter模型计算出7种金线鱼的遗传距离为0.042~0.294.S7序列存在大量碱基插入与缺失,其中日本金线鱼(Nemipterus japonicus)与苏门答腊金线鱼(N. mesoprion)在第167、182、474、608、662 bp位置,金线鱼(N. virgatus)与印度洋金线鱼(N. bipunctatus)第227、332、401、604 bp的位置具有相同的碱基插入缺失特征,且具有种类特异性.最后利用最大似然法(ML)与贝叶斯分析(BI)构建分子系统进化树,7种金线鱼聚在一起,其中日本金线鱼与苏门答腊金线鱼聚为一支,金线鱼、深水金线鱼和印度洋金线鱼聚成一支.结论认为需要结合多方面的形态与分子证据,才能进一步明确金线鱼属鱼类的系统进化关系.