尼氏单极虫(粘体门,双壳目)重描述及基于18S rDNA系统地位分析

采用常规细胞学方法与18S rDNA序列比较的方法,对采自于重庆市嘉陵江段的粘孢子虫,尼氏单极虫Thelohanellus nikolskii进行了形态学和分子生物学的研究,此为首次在我国长江流域检获尼氏单极虫。本文在补充了尼氏单极虫中国种群18S rDNA序列信息的分析、比较基础上,探讨了该虫与相邻种属的系统关系,佐证了其分类学位置。     

三种稻飞虱体内类酵母共生菌18S rDNA和 ITS 5.8S rDNA序列克隆及进化分析

为研究水稻3种主要害虫灰飞虱Laodelphax striatellus、 褐飞虱Nilaparvata lugens和白背飞虱Sogatella furcifera体内类酵母共生菌（yeast-like symbiotes, YLS）的种属地位及与寄主的进化关系, 测定了其体内YLS的18S rDNA及ITS-5.8S rDNA的全长序列。基于3种稻飞虱体内YLS的18S rDNA序列比对表明, 褐飞虱YLS和白背飞虱YLS的一致性比其与灰飞虱YLS的高（褐飞虱YLS和白背飞虱YLS为98.91%, 灰飞虱YLS和褐飞虱YLS为95.74%, 灰飞虱YLS和白背飞虱YLS为96.02%）, 而基于ITS-5.8S rDNA序列比对, 灰飞虱YLS和白背飞虱YLS的一致性比其与褐飞虱YLS的要高（白背飞虱YLS和灰飞虱YLS为99.57%, 灰飞虱YLS和褐飞虱YLS为91.91%, 白背飞虱YLS和褐飞虱YLS为90.46%）。基于真菌18S rDNA和ITS-5.8S rDNA的系统发育树均表明, 3种稻飞虱体内YLS与其他已知真菌进化关系较远。本研究证实了昆虫真菌类共生菌与寄主形成了长期的进化关系, 从而形成了不同于已知真菌的分类地位。     

武汉单极虫(粘体门,双壳目)的重描述及基于18S rDNA序列系统发育分析

通过光镜、扫描电镜和18S rDNA序列对比,对寄生于异育银鲫Carassius auratus gibelio体表的粘孢子虫进行了形态学和分子生物学研究,鉴定其为武汉单极虫Thelohanellus wuhanensis,并发现了形态学新特征:膜状鞘的起始位置不同,且仅包围孢子后部;壳瓣底部内侧具“V”形褶皱;一片壳瓣前端有突起结构;缝脊直,突出明显;测得极丝全长为158.5 ～179.2 (170.7 ±5.7) μm.经18S rDNA序列对比,与T.wuhanensis[HQ613410]的相似率为99.87％.系统发育分析表明,单极虫与碘泡虫具有非常近的亲缘关系,将单极虫属与碘泡虫属二者归属于碘泡科的分类方法更合理.     

Phylogenetic position of yeast-like symbiotes from three rice planthoppers (Homoptera: Delphacidae ) based on 18S rDNA and ITS-5.8S rDNA sequences

为研究水稻3种主要害虫灰飞虱Laodelphax striatellus、褐飞虱Nilaparvata lugens和白背飞虱Sogatella furcifera体内类酵母共生菌( yeast-like symbiotes,YLS)的种属地位及与寄主的进化关系,测定了其体内YIS的18SrDNA及ITS-5.8S rDNA的全长序列.基于3种稻飞虱体内YLS的18S rDNA序列比对表明,褐飞虱YLS和白背飞虱YLS的一致性比其与灰飞虱YLs的高(褐飞虱YLS和白背飞虱YLS为98.91％,灰飞虱YLS和褐飞虱YLS为95.74％,灰飞虱YLS和白背飞虱YLS为96.02％),而基于ITS-5.8S rDNA序列比对,灰飞虱YLS和白背飞虱YLS的一致性比其与褐飞虱YLS的要高(白背飞虱YLS和灰飞虱YLS为99.57％,灰飞虱YLS和褐飞虱YIS为91.91％,白背飞虱YLS和褐飞虱YLS为90.46％).基于真菌18S rDNA和ITS-5.8S rDNA的系统发育树均表明,3种稻飞虱体内YLS与其他已知真菌进化关系较远.本研究证实了昆虫真菌类共生菌与寄主形成了长期的进化关系,从而形成了不同于已知真菌的分类地位.     

基于16S rDNA序列探讨十种臂尾轮虫的系统关系和分类地位

通过对角突臂尾轮虫、尾突臂尾轮虫、裂足臂尾轮虫、剪形臂尾轮虫、方形臂尾轮虫、壶状臂尾轮虫、红臂尾轮虫、镰肜臂尾轮虫、萼花臂尾轮虫和十指臂尾轮虫等十种臂尾轮虫和大肚须足轮虫的线粒体16s rDNA进行扩增和序列测序,结合Genebank 中十指臂尾轮虫的16S rDNA序列,使用MAGE软件构建了NJ(neighbor-joining method)树,使用mrbayes软件构建了贝叶斯树,探讨了十种臂尾轮虫之间的系统关系.结果表明,本研究所涉及的轮虫16S rDNA序列差异百分比均值为14.6%,可作为分子标记应用于轮虫属内种间系统关系研究;系统树均支持将十指臂尾轮虫、裂足臂尾轮虫隶属于臂尾轮属;壶状臂尾轮虫和红臂尾轮虫是两个独立的种.此外,还依据16S rDNA序列变异百分比推测了十种臂尾轮虫的分化时间.     

基于核糖体DNA联合序列的天牛总科高阶元分子系统学研究

【目的】利用核糖体DNA联合序列探讨天牛总科高阶元分子系统发育。【方法】本研究采用分子标记技术,分析测定了63种天牛核糖体28S rDNA D2和D3区以及18S rDNA V4和V7区的DNA序列,并采用邻接法、最大似然法和贝叶斯推论法分别构建了天牛总科2科6亚科63种的分子进化系统。【结果】序列联合比对分析,最终得到1 404 bp的联合数据组,其中可变位点446个（32.0%）,保守位点958（68.0%）,转换/颠换的平均值（R值）为1.73。28S rDNA和18S rDNA以及联合序列的饱和度分析显示碱基突变未达到饱和,说明这些序列适合于分子进化树的构建。利用不同系统发育重建方法得到进化树具有相似拓扑结构,结果支持沟胫天牛亚科、花天牛亚科和天牛亚科为单系群,这与形态学分类结果相似;狭胸天牛独立成为亚科得到了支持。【结论】利用28S rDNA D2和D3区以及18S rDNA V4和V7区联合序列成功构建出了天牛总科高阶元的系统发育树。研究表明联合序列分析是探讨天牛高阶元分类的有效的方法。     

以23S rDNA一个多变区作为分子标记对致病杆菌属细菌进行分类鉴定

【目的】致病杆菌属(Xenorhabdus)细菌是一类重要的生物杀虫剂,斯氏属昆虫病原线虫的共生菌,建立快速准确的分类鉴定方法,对研究开发这类细菌至关重要。【方法】本研究PCR扩增测序了本室保藏的26株,含20种已定名致病杆菌属细菌的一段845 bp的23S rDNA序列,构建了基于这段序列的致病杆菌属系统树并与基于几乎全长16S rDNA序列的相应系统树进行比较,分析了两者作为致病杆菌属细菌分类鉴定分子标记的优缺点。【结果】结果表明,与全长16S rDNA序列相比,所选择的23S rDNA序列片段所含可变位点、简约信息位点比例更高,遗传距离数值跨度大。【结论】上述结果显示该序列片段可用于致病杆菌属细菌进行分类鉴定,特别适用于对野外资源调查中采集到的大量菌株进行快速鉴定。     

倒刺鲃两极虫的宿主新记录及其分子系统学研究

为弄清倒刺鲃两极虫(Myxidium spinibarba)的宿主多样性和胭脂鱼(Myxocyprinus asiaticus)寄生黏孢子虫的种类组成, 研究基于形态和分子数据, 比较分析了寄生于不同宿主的倒刺鲃两极虫的形态学和形态计量学特征及分子系统发育关系。结果显示: 寄生于胭脂鱼和中华倒刺鲃的倒刺鲃两极虫株系在形态学和形态计量学上未出现显著性差异, 18S rDNA序列相似度为99.9%—100.0%, 遗传距离为0.000—0.001, 符合种内变异; 寄生于不同宿主倒刺鲃两极虫的株系在系统发育树中嵌合聚支, 且寄生于胭脂鱼的倒刺鲃两极虫株系先分化。以上结果表明: 研究中两株系与倒刺鲃两极虫为同一物种, 但在分子水平已经出现分化; 这是首次在胭脂鱼中检获到黏孢子虫, 胭脂鱼是倒刺鲃两极虫的新宿主。     

碘泡虫属粘孢子虫分子进化及其与宿主协同关系的研究

以18S rDNA为分子标记,对碘泡虫属Myxobolus粘孢子虫的分子进化规律进行了系统研究。结果显示:碘泡虫属各物种18S rDNA的AT含量(53.2%)高于GC含量(46.8%),表现出一定的AT组成偏向性;各物种18S rDNA遗传距离在0.00~0.35;脑碘泡虫M.cerebralis保守区序列变异介于淡水物种和广盐性物种之间;碘泡虫属18S rDNA分子系统发育树呈现生境相同先聚枝,形态相似后聚枝的规律,并表现出一定的宿主特异性和组织向性。此外,以线粒体COⅠ基因为分子标记,对碘泡虫属相应宿主进行了系统进化分析,结果表明:淡水物种与广盐性物种分别聚在不同的分类枝系中,与寄生于宿主体内的碘泡虫所呈现的支序树有相同的进化趋势,并表现出一定的协同进化关系;海水起源的虹鳟Oncorhynchus mykiss在适应淡水过程中被脑碘泡虫寄生,两者经过长期的演化,最终适应淡水环境。     

全长rDNA簇在蝽类昆虫生命树构建中的应用前景(昆虫纲,半翅目)

在昆虫纲中,生命树计划正在以目级阶元中的分类单元为单位逐步推进.针对这一大的背景,以及高级阶元和种级阶元分子系统学研究间脱节现状,提出以rDNA簇为一组分子标记、并且在未来高级阶元系统发育研究中将目前选取少量代表类群的做法改为将尽量多的物种包含到一棵系统发育树中的建议.其中首先简要介绍了rDNA簇的结构及其中各分子标记在分子系统学研究中的应用价值,随后以蝽类昆虫为例,有针对性地总结了rDNA簇中不同基因序列已有数据的丰富程度及其在分子系统学研究中的应用情况.首次给出了蝽类昆虫28S rRNA近全长序列的二级结构模型.基于对18S rRNA和28S rRNA二级结构研究所积累的认识,强调了18S rDNA和28S rDNA内部不同区段之间变异模式和应用价值的差异,论证了未来在生命树构建中深化对rDNA簇中各基因进行联合应用的合理性和可行性.     

Description of two new gill myxozoans from smallmouth (Micropterus dolomieu) and largemouth (Micropterus salmoides) bass

Two previously undescribed species of myxozoan parasites were observed in the gills of bass inhabiting the Potomac and James River basins. They are described using morphological characteristics and small-subunit (SSU) rDNA gene sequences. Both were taxonomically identified as new species of Myxobolus; Myxobolus branchiarum n. sp. was found exclusively in smallmouth bass, and Myxobolus micropterii n. sp. was found in largemouth and smallmouth bass. Small, spherical, white plasmodia of M. branchiarum from smallmouth bass were observed grossly in the gills; these plasmodia had an average length of 320.3 μm and width of 246.1 μm. The development of the plasmodia is intralamellar in the secondary lamellae of the gills. Mature spores were pyriform in shape with a length of 12.8 ± 1.4 (8.1-15.1) μm and width of 6.9 ± 1.1 (4.0-9.0) μm. Analysis of SSU rDNA identified M. branchiarum in a sister-group to 3 species of Henneguya , although morphologically caudal appendages were absent. Myxobolus micropterii observed in the gills of largemouth and smallmouth bass had larger, ovoid, cream-colored plasmodia with an average length of 568.1 μm and width of 148.1 μm. The cysts developed at the distal end of the gill filament within the primary lamellae. The mature spores were ovoid in shape with a length of 10.8 ± 0.7 (9.2-12.2) μm and width of 10.6 ± 0.6 (9.0-11.8) μm. SSU rDNA analysis placed M. micropterii in a sister group with Henneguya lobosa and Myxobolus oliveirai . The highest prevalence of M. branchiarum was observed in the gills of bass collected from the Cowpasture River (50.9%). Prevalence was 44.6% in bass from the Potomac River and only 4.3% in bass collected from the Shenandoah River. A seasonal study of M. branchiarum , which included both infected and uninfected smallmouth bass, determined that a significantly higher intensity was observed in the spring than in the summer (P < 0.001) or fall (P = 0.004). In an analysis excluding uninfected bass, a higher intensity was observed in the spring than in the summer (P = 0.001) or fall (P = 0.008). Prevalence and seasonal differences were not determined for M. micropterii .     

基于18S rDNA与ITS-5.8S rDNA对 重庆地区网状车轮虫的种内分化研究

本研究基于形态和分子数据对采自重庆地区5个地理株系的网状车轮虫(Trichodina reticulata)进行了比较研究及重描述。研究结果表明,网状车轮虫不同株系表现出不同的表型分化,含形态略有不同的齿体及有或无中央颗粒,因而具有明显的种内形态多样性。不同地理株系网状车轮虫的18S rDNA序列相似度在99.0%~100%之间,遗传距离为0.000~0.008,并在三大变异区(V4、V5与V7)均具一致的二级结构,表明不同株系的18Sr DNA相似度与遗传距离均属种内水平。综合18SrDNA和ITS-5.8S rDNA的变异位点和系统发育对种内分歧的研究分析显示,来自不同地理分布和宿主的网状车轮虫株系皆因相同的变异位点而聚为一枝,以此推断网状车轮虫的种内分化主要受其基因的影响,地理分布与宿主差异等环境影响在目前的种群分化阶段暂未突显。此外,本研究进一步验证了中央颗粒不能作为网状车轮虫的主要鉴别性特征的观点。     

Four New Species of Myxosporidia from the Indian Fresh Water Fish Ophicephalus punctatus Bloch

SYNOPSIS. Four new species of Myxosporidia have been described from Ophicephalus punctatus , a fresh water fish of North India: Myxobolus aligarhensis n. sp., M. ophicephali n. sp., Unicauda basiri n. sp., and Henneguya zahoori n. sp. Observations have been made on some stages of their life-cycle other than the spores.     

鲤肠道寄生岳阳碘泡虫新种的形态特征及系统发育分析

在洞庭湖岳阳地区开展鱼类寄生虫调查中,发现一种寄生于鲤Cyprinus carpio L.肠道的黏孢子虫。该黏孢子虫的孢囊呈白色,椭圆形,大小为(1.0±0.2) mm (0.8—1.2 mm)。成熟孢子具有壳瓣,壳面观近似圆形,后端有4—6个“V”形褶皱;缝面观呈纺锤形,缝脊直而粗;孢质均匀,含有一个嗜碘泡;孢子长(9.8±0.6) μm (9.6—10.0 μm),孢子宽(8.2±0.3) μm (8.0—8.5μm),孢子厚(7.3±0.1) μm (7.0—7.5 μm);2个极囊梨形,位于孢子顶端,大小相等,呈“八”字形;极囊长(4.4±0.4) μm (3.8—5.1 μm),宽(2.7±0.2) μm (2.2—3.2 μm),极丝4—5圈。该黏孢子虫与肠膜碘泡虫、丑陋圆形碘泡形态特征非常相似,但其极囊/孢子小于1/2;与文献已报道的鲤肠道寄生北京碘泡虫和鲤肠碘泡虫相比较,其在孢子形态、孢子和极囊大小方面分别存在明显差异。基于该黏孢子虫18S rDNA基因序列(GenBank登录号KY203795)比对分析,该黏孢子虫与山东碘泡虫相似率最高,仅为96%。系统发育分析发现,该黏孢子虫与山东碘泡虫、倪李碘泡虫、住心碘泡虫、Myxobolus encephalicus、Sphaerospora molnari、多涅茨尾孢虫和Henneguya zikaweiensis聚为独立分支,和其他已报道的黏孢子虫亲缘关系较远。综合形态学和18S rDNA基因序列数据,文章报道的鲤肠道寄生黏孢子虫为碘泡虫属一新物种,将其命名为岳阳碘泡虫。     

Secondary structure prediction for complete rDNA sequences (18S, 5.8S,and 28S rDNA) of Demodex folliculorum, and comparison of divergent domains structures across Acari

According to base pairing, the rRNA folds into corresponding secondary structures, which contain additional phylogenetic information. On the basis of sequencing for complete rDNA sequences (18S, ITS1, 5.8S, ITS2 and 28S rDNA) of Demodex, we predicted the secondary structure of the complete rDNA sequence (18S, 5.8S, and 28S rDNA) of Demodex folliculorum, which was in concordance with that of the main arthropod lineages in past studies. And together with the sequence data from GenBank, we also predicted the secondary structures of divergent domains in SSU rRNA of 51 species and in LSU rRNA of 43 species from four superfamilies in Acari (Cheyletoidea, Tetranychoidea, Analgoidea and Ixodoidea). The multiple alignment among the four superfamilies in Acari showed that, insertions from Tetranychoidea SSU rRNA formed two newly proposed helixes, and helix c3-2b of LSU rRNA was absent in Demodex (Cheyletoidea) taxa. Generally speaking, LSU rRNA presented more remarkable differences than SSU rRNA did, mainly in D2, D3, D5, D7a, D7b, D8 and D10.     

尖形碘泡虫(黏体门:碘泡虫科)的重描述及其分子系统学研究

研究基于形态和分子信息重描述了寄生于嘉陵江重庆段鲫(Carassius auratus Linnaeus)鳃部和胆囊的尖形碘泡虫(Myxobolus acutus Wu and Chen, 1987),并获得了该虫体的18S rDNA和ITS1 rDNA序列。尖形碘泡虫成熟孢子壳面观呈梨形,前端稍尖,后端钝圆,缝面观呈宽纺锤形。孢子长(13.6±0.9)μm [(11.4—15.3)μm],宽(10.2±0.9)μm [(7.5—12.8)μm],厚(7.6±0.6)μm [(6.9—8.3)μm]。两梨形极囊开口处紧靠并位于孢子前端,极囊大小不等,大极囊长(6.2±0.4)μm [(5.1—7.5)μm],宽(3.8±0.4)μm [(2.8—4.7)μm],极丝盘绕5—8圈,小极囊长(2.7±0.4)μm [(1.7—3.7)μm],宽(1.4±0.2)μm [(0.9—1.9)μm],极丝盘绕2—3圈。基于18S rDNA为分子标记的系统发育分析显示:尖形碘泡虫与中华单极虫(Thelohanellus sinensis)有最近的亲缘关系,两物种形成的进化支与贝壳碘泡虫(M. mu...     

Phylogeny of the Platyhelminthes and the evolution of parasitism

Robust phylogenies provide the basis for interpreting biological variation in the light of evolution. Homologous features provide phylogenetically informative characters whereas homoplasious characters provide phylogenetic noise. Both provide evolutionary signal. We have constructed molecular and morphologically based phylogenies of the phylum Platyhelminthes using a recently revised morphological character matrix and complete 18S and two partial 28S rRNA gene sequences in order to evaluate the emergence and subsequent divergence of parasitic forms. In total we examine 65 morphological characters, 97 18S rDNA, 41 Dl domain 28S rDNA, and 49 D3-D6 domain 28S rDNA sequences. For the molecular data there were 748, 132 and 249 phylogenetically informative sites for the 18S, Dl and D3-D6 28S rDNA data sets respectively. Morphological and molecular phylogenetic solutions are incongruent but not incompatible, and using the principles of conditional combination (18S rDNA + morphology passing Templeton's test) they demonstrate: a single and relatively early origin for the parasitic Neodermata (including the cestodes, trematodes and monogeneans); sister-group status between the cestodes and monogeneans, and between these taxa and the trematodes (digeneans and aspidogastreans). The sister-group to the Neodermata is likely to be a large clade of neoophoran turbellarians, based on combined evidence, or a clade consisting of the Fecampiid + Urastomid turbellarians, based on morphological evidence alone. The combined evidence solution for the phylogeny of fiatworms based on 18S rDNA and morphology is used to interpret morphological and life-history data and to support a model for the evolution and radiation of neodermatan parasites in the group.     

葡萄碘泡虫、似葡萄碘泡虫和茄形碘泡虫的鉴别及系统发育

葡萄碘泡虫Myxobolus acinosus Nie & Li, 1973、似葡萄碘泡虫Myxobolus pseudoacinosus Guo, et al., 2018和茄形碘泡虫Myxobolus toyamai Kudo, 1917形态非常相似, 有着共同的宿主和相同的寄生部位, 是病原鉴定中容易混淆的种。文章基于形态学和18S rRNA基因信息对三者进行了鉴别和分子系统学研究。成熟孢子形态特征的比较分析显示, 三者形态存在显著差异。葡萄碘泡虫与似葡萄碘泡虫18S rDNA序列相似度为98.4—98.8%, 遗传距离为0.013—0.020; 葡萄碘泡虫与茄形碘泡虫18S rDNA序列相似度为96.1—97.2%, 遗传距离为0.038—0.042; 似葡萄碘泡虫和茄形碘泡虫18S rDNA序列相似度为96.4—97.6%, 遗传距离为0.033—0.040。18S rDNA序列比对显示, 葡萄碘泡虫含有15个关键变异位点, 可将该虫与似葡萄碘泡虫和茄形碘泡虫区分; 似葡萄碘泡虫含有5个关键变异位点, 可将该虫与葡萄碘泡虫和茄形碘泡虫区分; 茄形碘泡虫含有33个关键变异位点可将该虫与葡萄碘泡虫和似葡萄碘泡虫区分。18S rRNA二级结构V4区的E23-2构型可将葡萄碘泡虫与似葡萄碘泡虫和茄形碘泡虫区分, 而V7区的H43构型可将茄形碘泡虫与葡萄碘泡虫和似葡萄碘泡虫区分。以上表明, 三者无论在形态上还是在遗传上均具有独立物种的特征。系统发育分析显示, 葡萄碘泡虫、似葡萄碘泡虫和茄形碘泡虫为系统树中分化较晚的一支。