Ascovirus and its Evolution

Ascoviruses, iridoviruses, asfarviruses and poxviruses are all cytoplasmic DNA viruses. The evolutionary origins of cytoplasmic DNA viruses have never been fully addressed. Morphological, genetic and molecular data were used to test if all four cytoplasmic virus families (Ascoviridae, Iridoviridae, Asfarviridae, and Poxvirirdae) evolved from nuclear replicating baculoviruses and how the four virus groups are related. Molecular phylogenetic analyses using DNA polymerase predicted that cytoplasmic DNA viruses might have evolved from nuclear replicating baculoviruses, and that poxviruses and asfarviruses share a common ancestor with iridoviruses. These three cytoplasmic viruses again shared a common ancestor with ascoviruses. Morphological and genetic data predicted the same evolutionary trend as molecular data predicted. A genome sequence comparison showed that ascoviruses have more baculovirus protein homologues than do iridoviruses, which suggested that ascoviruses have evolved from baculoviruses and iridoviruses evolved from ascoviruses. Poxviruses showed genetic and morphological similarity to other cytoplamic viruses, such as ascoviruses, suggesting it has undergone reticulate evolution via hybridization, recombination and lateral gene transfer with other viruses. Within the ascovirus family, we tested if molecular phylogenetic analyses agree with biological inference; that is, ascovirus had an evolutionary trend of increasing genome size, expanding host range and widening tissue tropism for these viruses. Both molecular and biological data predicted this evolutionary trend. The phylogenetic relationship among the four species of ascovirus was predicted to be that TnAV-2 and HvAV-3 shared a common ancestor with SfAV-1 and the three virus species again shared a common ancestor with DpAV-4.     

Lateral gene transfer, lineage-specific gene expansion and the evolution of Nucleo Cytoplasmic Large DNA viruses

Nucleo Cytoplasmic Large DNA viruses (NCLDVs) are a diverse group that infects a wide range of eukaryotic hosts (for example, vertebrates, insects, protists,…) and also show a huge range in genome size (between 100 kb and 1.2 Mb). Here I review some recent results that shed light on the origin and genome evolution of these viruses. Current data suggests that NCLDVs could have originated from a simple and ancient viral ancestor with a small subset of 30-35 genes encoding replication and structural proteins. Subsequent lateral gene transfer of both cellular genes and diverse families of Mobile Genetic Elements, followed by massive lineage-specific gene duplications is probably responsible for the huge diversity of genome size and composition found in extant NCLDVs.     

中国貉线粒体DNA多态性及其与亚种分化的关系

本文以８种限制性内切酶对来自７个地区的１４只中国貉进行了ｍｔＤＮＡ的ＲＦＬＰ分析,并构建了貉ｍｔＤＮＡ的限制酶物理图谱。根据各群体间的遗传距离构建ＵＰＧ分子系统树,结合形态、地理分布资料对中国貉的亚种分化进行了探讨。结果表明,中国貉的指名亚种已发生明显的遗传分化;对于分类地位没有确定的华北和陕西群体,建议将它们各自单独定为一个亚种;中国貉最先发生南北分歧,然后发生东西分歧。     

基于部分18S rDNA, 28S rDNA和COI基因序列的索科线虫亲缘关系

通过PCR扩增获得我国常见昆虫病原索科线虫6属10种18S rDNA、28S rDNA(D3区)和COI基因序列,结合来自GenBank中6属10种索科线虫的18S rDNA同源序列,用邻接法和最大简约法构建系统进化树。结果显示:12属索科线虫分为三大类群,第一大类群是三种罗索属线虫(Romanomermis)先聚在一起,再与两索属(Amphimermis)和蛛索属(Aranimermis)线虫聚为一支;在第二大类群中,六索属(Hexamermis)、卵索属线虫(Ovomermis)和多索属(Agamermis)亲缘关系最近,先聚在一起,再与八腱索属(Octomyomermis)和Thaumamermis线虫聚为一支。第三大类群由索属(Mermis)和异索属(Allomermis)线虫以显著水平的置信度先聚在一起,再与蠓索属(Heleidomermis)和施特克尔霍夫索属(Strelkovimermis)线虫聚为一支。从遗传距离看,基于3个基因的数据集均显示索科线虫属内种间差异明显小于属间差异,武昌罗索线虫(R.wuchangensis)和食蚊罗索线虫(R.culicivorax)同属蚊幼寄生罗索属线虫,其种间的遗传距离最小。     

两种锦鸡和环颈雉线粒体DNA(mtDNA)的比较研究

本文以10种限制性内切酶分析雉科中环颈雉,红腹锦鸡和白腹锦鸡线粒体DNA（mtDNA）。雉属与锦鸡属之间的遗传距离P为0.076（0.067-0.085）,红腹锦鸡与白腹锦鸡的P为0.012。推算雉属和锦鸡属的分化大约发生在3.8×10[6]年以前,红腹锦鸡与白腹锦鸡的分化大约在6×10[5]年以前。这些结果表明：1.在雉科系统发生中,雉属与锦鸡属是近缘的属;2.红腹锦鸡和白腹锦鸡的分化较晚,关系密切,可能只是两个亚种。     

旋花科植物雄性细胞的细胞质DNA存在状况及其系统学意义

用DAPI荧光染色方法检测了旋花科4属4种植物——空心菜Ipomoea aquatica Forsk. 、茑萝 Qua-moclit pennata (Desr．)Boj．、月光花 Calonyction aculeatum(L．)House和日本菟丝子Cuscuta japonica Choisy中生殖细胞和精细胞中细胞质DNA存在的状况。证明除日本菟丝子外,其余3种植物的雄性细胞中都存在细胞质DNA。此外,在我们曾研究过的5种旋花科种植物的生殖细胞和精细胞中亦显示含有细胞质DNA,因而可认为这是旋花科较普遍的特性,日本菟丝子精细胞中缺少细胞质DNA,可作为—个新的胚胎学证据,支持此属从旋花科分出独立为菟丝子科。     

洋葱细胞质雄性不育系70及其保持系71基因组DNA的RAPD分析

采用RAPD技术,对洋葱细胞质雄性不育系70及其保持系71的基因组DNA的多态性进行分析。结果表明,在被检测的100条随机引物中,46条引物具有扩增产物,5条引物扩增出多态性条带。对这5条引物进行重复筛选和单株验证,只有G02扩增出的多态性片段,且表现稳定。推测该标记与育性有关。     

Intra- and interbreed genetic variations of mitochondrial DNA major non-coding regions in Japanese native dog breeds [Canis familiaris)

Mitochondrial DNA (mtDNA) major non-coding regions were amplified from 73 dogs of eight Japanese native dog breeds and from 21 dogs of 16 non-Japanese dog breeds by the polymerase chain reaction and their DNA sequences were determined. A total of 51 nucleotide positions within the non-coding region (969–972 base pairs) showed nucleotide variations of which 48 were caused by transition. These nucleotide substitutions were abundant in the region proximate to tRNA^Pro. In addition to the nucleotide substitutions, the dog mtDNA D-loop sequences had a heteroplasmic repetitive sequence (TACACGTÀCG) involving size variation. The DNA sequences of the non-coding region were classified into four different groups by phylogenetic analysis and the deepest branchpoints of this dog phylogeny was calculated to about 100 000 years before the present. Phylogenetic analysis showed that Japanese native dog breeds could not be clearly delimited as distinct breeds. Many haplotypes found in members of some clustering groups were seen in each dog breed, and interbreed nucleotide differences between Japanese dog breeds were almost the same as the intrabreed nucleotide diversities.     

鱼类线粒体DNA及其研究进展

鱼类是脊椎动物中最原始而在种属数量上又最占优势的类群,其起源复杂,分布广泛,拥有丰富的遗传多样性。鱼类线粒体DNA(mitochondrial DNA,mtDNA)同其他脊椎动物的mtRNA一样,呈共价闭合环状,是细胞核外具自主复制、转录和翻译能力的遗传因子。与核DNA相比,鱼类mtDNA具有分子较小、结构简单、进化速度快、遗传相对独立性和母系遗传等特点,是一个相对独立的复制单位。由于鱼类线粒体DNA具有上述特点,以mtDNA作为分子标记,探讨鱼类的群体遗传结构与系统演化,已成为鱼类分子群体遗传学和系统学研究中的热点。综述了鱼类mtDNA的结构特征、进化和多态性检测方法及其在鱼类分子群体遗传学和鱼类系统学研究中的应用。     

Baculoviruses as Vectors in Mammalian Cells

The Baculoviridae are a large family of enveloped DNA viruses exclusively pathogenic to arthropods. Baculoviruses have been extensively used in insect cell-based recombinant protein expression system and as biological pesticides. They have been deomostrated to be safe to mammals, birds and fish. Recently, baculoviruses has been shown to transduce different mammalian cells in spite of the fact that they cannot replicate in mammalian cells (11, 73, 76). This has resulted in the development of baculoviruses as mammalian expression systems and even as vestors for gene therapy.     

安徽某淡水龙虾养殖群体分类的分子标记筛选

为筛选可用于淡水龙虾养殖群体物种分类的分子标记,对安徽省某水产养殖有限公司采集的淡水龙虾样本进行了线粒体COⅠ、16S rDNA、D-loop、Cyt b及12S rDNA基因的测序分析,并与GenBank中30个滑螯虾属(Cherax)物种的相应基因序列比对,同时,进行上述5种分子标记在种内个体间、属内种间、科内属间和目内科间的同源性变异范围比对分析。结果显示,本研究所采集淡水龙虾样本与四脊滑螯虾(C. quadricarinatus)的相似性最高,其中,1 113 bp的Cyt b相似性100%,COⅠ、16S r DNA及12S rDNA相似性都在99%以上;在以克氏原螯虾(Procambarus clarkii)为外类群构建的邻接系统发育树中,本研究样本与四脊滑螯虾聚为一支,然后与其他物种聚合构成系统树,确定本研究采集的淡水龙虾样本为四脊滑螯虾;通过同源性变异范围比对分析,在淡水龙虾养殖群体的分子分类工作中,16S rDNA、Cyt b及12S rDNA比COⅠ和D-loop这2种分子标记具有较强优势。本研究结果可为今后淡水龙虾养殖场中物种的分类鉴定工作提供参考。     

Baculoviruses as vectors in mammalian cells

The Baculoviridae are a large family of enveloped DNA viruses exclusively pathogenic to arthropods. Baculoviruses have been extensively used in insect cell-based recombinant protein expression system and as biological pesticides. They have been deomostrated to be safe to mammals, birds and fish. Recently, baculoviruses has been shown to transduce different mammalian cells in spite of the fact that they cannot replicate in mammalian cells (11, 73, 76). This has resulted in the development of baculoviruses as mammalian expression systems and even as vestors for gene therapy. Foundation item: National Nature Science Foundations of China (30325002, 30470075).     

团藻目分子系统学研究进展

包含许多重要类群的团藻目在绿色植物系统演化中占有十分重要的地位。普遍认为现在的绿色植物起源于团藻目的绿色鞭毛类 ,有人认为鞭毛细胞表面覆盖有鳞片的塔胞藻类是绿色植物的祖先。团藻目是分子系统学研究比较多和比较深入的一个类群 ,通过研究证实其有单一共同祖先 ,而莱茵衣藻在所有已经经过DNA测序分析系统发育的绿色单细胞类群中是最可能的种类。本文结合自己的工作 ,对国内外这一研究领域概况进行综述。     

分子检测技术对活性污泥中氨氧化细菌的比较研究

采用PCR扩增、随机克隆测序等技术,分析处理含高浓度氨氮的废水处理系统不同驯化时期的4个活性污泥样品,对样品中氨氧化细菌（AOB）的种类和氨单加氧酶（AMO）的活性进行分析比较,并在国内首次采用PCR变性梯度凝胶电泳（DGGE）相结合的技术对样品中总的细菌类群的差异进行研究。结果表明所检测到的氨氧化细菌优势菌群均属于变形细菌的β亚类,与Nitrosomonas sp.具有较高的相似性。活性污泥驯化成熟后,废水处理系统中AMO的活性有明显提高,活性污泥中的细菌类群更加集中,优势菌群相对稳定,系统对废水的处理效率也相应提高。结果表明采用分子检测技术有利于更全面地了解AOB的类群和功能,进而改善废水处理系统的处理效果。     

Molecular evolution and phylogeny of the human AIDS viruses LAV,HTLV-III,and ARV

Summary A phylogenetic tree for the human lymphadenopathy-associated virus (LAV), the human T-cell lymphotrophic virus type III (HTLV-III), and the acquired immune deficiency syndrome (AIDS)-associated retrovirus (ARV) has been constructed from comparisons of the amino acid sequences of their gag proteins. A method is proposed for estimating the divergence times among these AIDS viruses and the rates of nucleotide substitution for their RNA genomes. The analysis indicates that the LAV and HTLV-III strains diverged from one another after 1977 and that their common ancestor diverged from the ARV virus no more than 10 years earlier. Hence, the evolutionary diversity among strains of the AIDS viruses apparently has been generated within the last 20 years. It is estimated that the genome of the AIDS virus has a nucleotide substitution rate on the order of 10^–3 per site per year, with the rate in the second half of the genome being double that in the first half.