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。     

Genetic diversity and phylogenetic relations of salmon trematode Nanophyetus japonensis

Nanophyetiasis is the severe zoonotic disease caused by parasitic worms from the genus Nanophyetus. Humans and carnivorous animals become infected when they ingest raw fish containing metacercariae, especially Pacific salmonids. Nanophyetiasis is detected in limited geographical areas which include the coastal regions of the North Pacific: the United States of America, Russian Federation and Japan. Despite the epidemiological significance, Nanophyetus species have not been well studied genetically. In this research, we for the first time explored genetic diversity of Nanophyetus japonensis from Japan in comparison with those of related species, N. salmincola from North America and N. schikhobalowi from the Russian Far East, based on sequence variation in the nuclear ribosomal gene family (18S, ITS1–5.8S–ITS2 and 28S) and mitochondrial nad1 gene, encoding subunit I of the respiratory chain NADH dehydrogenase. The results confirmed the independent species status for the compared flukes, demonstrated a greater genetic similarity of Asian species between themselves than each of them with the North American one, suggesting that N. japonensis and N. schikhobalowi are close sister species, and also revealed discrepancy between the levels of morphological and genetic differentiation.     

A review of the subgenus Epicterodes of Arichanna (Lepidoptera,Geometridae, Ennominae), with description of one new species

The subgenus Epicterodes Wehrli, 1933 of Arichanna Moore, 1868 is reviewed. Six species are recognized, of which, A. (E). denticularia sp. nov. is described as new to science from China. One new synonym is established based on morphological and genetic similarity: A. (E.) flavomacularia Leech, 1897 (=A. (E.) perimelaina Wehrli, 1933 syn. nov.). Results of DNA barcoding for Epicterodes are briefly discussed. Diagnoses for all the species are provided and illustrations of adults, genitalia and distribution map are presented.     

Longidorus ferrisi n. sp. from California Citrus

In October 1999, the authors received fixed specimens of a species of Longidorus from Howard Ferris found about the roots of a citrus tree in Oakville, Napa County, CA. After determining it to be new a species, we requested additional specimens. The samples contained roughly equal numbers of males and females. Longidorus ferrisi n. sp. is most similar to L. elongatus, but can be distinguished by a greater c-ratio (111-187 vs 73-141), a lesser c′ (0.7-1.1 vs 1.0-1.3), a more offset head, a more posterior guide ring (35-40 vs 30-33 μm), the presence of sperm in the uterus in mature females, and the approximate 1:1 ratio of females to males. Other similar species include L. artemisiae, L. crassus, L. glycines, and L. milanis. Longidorus ferrisi n. sp. differs from L. artemisiae by a lesser a-ratio (74-102 vs 109-155), a lesser c′ value (0.7-1.1 vs 1.0-1.6), a more posterior guide ring (35-40 vs 27-34 μm), a longer odontostyle (91-108 vs 84-98 μm), a wider lip region (16-19 vs 14-17 μm), wider mid-body (53-69 vs 41-52 μm), and longer spicules (57-65 vs 39-49 μm). The new species differs substantially from L. crassus by its lip shape and the presence of males, and differs from L. glycines by a shorter body (4.33-5.97 vs 6.14-8.31 mm), a lesser c′ value (0.7-1.1 vs 0.9-1.4), a narrower lip region (16-19 vs 20-23 μm), wider mid-body (53-69 vs 39-57 μm), longer spicules (53-69 vs 45-53 μm), and fewer supplements (7-11 vs 11-17). Longidorus ferrisi n. sp. differs from L. milanis by a longer body (4.33-5.97vs 3.00-4.90 mm), a greater c value (111-187 vs 86-130), a wider mid-body (53-69 vs 43-56 μm), a different head shape, and longer spicules (53-69 vs 41-54 μm). The nuclear 18S ribosomal DNA sequence of this species revealed that this species is unique with respect to all sequenced Longidorus species.     

Unusual sequences,homologous to 5S RNA,in ribosomal DNA repeats of the nematodeMeloidogyne arenaria

Summary There are sequences homologous to 5S ribosomal RNA in the ribosomal DNA (rDNA) repeats of the plant-parasitic nematodeMeloidogyne arenaria. This is surprising, because in all other higher eukaryotes studied to date, the genes for 5S RNA are unlinked to and distinct from a tandem rDNA repeat containing the genes for 18S, 5.8S, and 28S ribosomal RNA. Previously, only prokaryotes and certain lower eukaryotes (protozoa and fungi) had been found to have both the larger rRNAs and 5S rRNA represented within a single DNA repeat. This has raised questions on the organization of these repeats in the earliest cell (progenote), and on subsequent evolutionary relationships between pro- and eukaryotes.Evidence is presented for rearrangements and deletions withinMeloidogyne rDNA. The unusual life cycles (different levels of ploidy, reproduction by meiotic and mitotic parthenogenesis) of members of this genus might allow rapid fixation of any variants with introduced 5S RNA sequences. The 5S RNA sequences inMeloidogyne rDNA may not be expressed, but their presence raises important questions as to the evolutionary origins and stability of repeat gene families.     

Phylogenetic relationships of Nembrothinae (Mollusca: Doridacea: Polyceridae) inferred from morphology and mitochondrial DNA

Within the Polyceridae, Nembrothinae includes some of the most striking and conspicuous sea slugs known, although several features of their biology and phylogenetic relationships remain unknown. This paper reports a phylogenetic analysis based on partial sequences of two mitochondrial genes (cytochrome c oxidase subunit I and 16S rRNA) and morphology for most species included in Nembrothinae. Our phylogenetic reconstructions using both molecular and combined morphological and molecular data support the taxonomic splitting of Nembrothinae into several taxa. Excluding one species (Tambja tentaculata), the monophyly of Roboastra was supported by all the phylogenetic analyses of the combined molecular data. Nembrotha was monophyletic both in the morphological and molecular analyses, always with high support. However, Tambja was recovered as para- or polyphyletic, depending on the analysis performed. Our study also rejects the monophyly of "phanerobranch" dorids based on molecular data.     

Multiple origins of anural development in ascidians inferred from rDNA sequences

Ascidians exhibit two different modes of development. A tadpole larva is formed during urodele development, whereas the larval phase is modified or absent during anural development. Anural development is restricted to a small number of species in one or possibly two ascidian families and is probably derived from ancestors with urodele development. Anural and urodele ascidians constitute a model system in which to study the evolution of development, but the phylogeny of anural development has not been resolved. Classification based on larval characters suggests that anural species are monophyletic, whereas classification according to adult morphology suggests they are polyphyletic. In the present study, we have inferred the origin of anural development using rDNA sequences. The central region of 18S rDNA and the hypervariable D2 loop of 28S rDNA were amplified from the genomic DNA of anural and urodele ascidian species by the polymerase chain reaction and sequenced. Phylogenetic trees inferred from 18S rDNA sequences of 21 species placed anural developers into two discrete groups corresponding to the Styelidae and Molgulidae, suggesting that anural development evolved independently in these families. Furthermore, the 18S rDNA trees inferred at least four independent origins of anural development in the family Molgulidae. Phylogenetic trees inferred from the D2 loop sequences of 13 molgulid species confirmed the 18S rDNA phylogeny. Anural development appears to have evolved rapidly because some anural species are placed as closely related sister groups to urodele species. The phylogeny inferred from rDNA sequences is consistent with molgulid systematics according to adult morphology and supports the polyphyletic origin of anural development in ascidians. Correspondence to: W.R. Jeffery     

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。     

Starting to unravel the toxoglossan knot: molecular phylogeny of the "turrids" (Neogastropoda: Conoidea)

The superfamily Conoidea is one of the most speciose groups of marine mollusks, with estimates of about 340 recent valid genera and subgenera, and 4000 named living species. Previous classifications were based on shell and anatomical characters, and clades and phylogenetic relationships are far from well assessed. Based on a dataset of ca. 100 terminal taxa belonging to 57 genera, information provided by fragments of one mitochondrial (COI) and three nuclear (28S, 18S and H3) genes is used to infer the first molecular phylogeny of this group. Analyses are performed on each gene independently as well as for a data matrix where all genes are concatenated, using Maximum Likelihood, Maximum Parsimony and Bayesian approaches. Several well-supported clades are defined and are only partly identifiable to currently recognized families and subfamilies. The nested sampling used in our study allows a discussion of the classification at various taxonomical levels, and several genera, subfamilies and families are found polyphyletic.     

Trichinella zimbabwensis n.sp. (Nematoda), a new non-encapsulated species from crocodiles (Crocodylus niloticus) in Zimbabwe also infecting mammals

Since 1995, Trichinella larvae have been detected in 39.5% of farmed crocodiles (Crocodylus niloticus) in Zimbabwe. Morphological, biological, biochemical and molecular studies carried out on one isolate from a farmed crocodile in 2001 support the conclusion that this parasite belongs to a new species, which has been named Trichinella zimbabwensis n.sp. This species, whose larvae are non-encapsulated in host muscles, infects both reptiles and mammals. The morphology of adults and larvae is similar to that of Trichinella papuae. Adults of T. zimbabwensis cross in both directions with adults of T. papuae (i.e. male of T. zimbabwensis per female of T. papuae and male of T. papuae per female of T. zimbabwensis), producing F1 offspring which produce very few and less viable F2 larvae. Muscle larvae of T. zimbabwensis, like those of T. papuae, do not infect birds. Three allozymes (of a total of 10) are diagnostic between T. zimbabwensis and T. papuae, and five are diagnostic between T. zimbabwensis and Trichinella pseudospiralis, the third non-encapsulated species. The percentage of the pairwise alignment identity between T. zimbabwensis and the other Trichinella species for the cytochrome oxidase subunit I gene, the large subunit ribosomal-DNA (mt-lsrDNA) gene and the expansion segment five, shows that T. zimbabwensis is more similar to the two non-encapsulated species T. papuae (91% for cytochrome oxidase I; 96% for mt-lsrDNA; and 88% for expansion segment five) and T. pseudospiralis (88% for cytochrome oxidase I; 90% for mt-lsrDNA; and 66–73% for expansion segment five) than to any of the encapsulated species (85–86% for cytochrome oxidase I; 88–89% for mt-lsrDNA; and 71–79% for expansion segment five). This is the first non-encapsulated species discovered in Africa. The finding of a new Trichinella species that infects both reptiles and mammals suggests that the origin of Trichinella parasites dates back further than previously believed and can contribute to understanding the phylogeny and the epidemiology of the genus Trichinella.     

Evolutionary relationships within the protostome phylum Sipuncula: a molecular analysis of ribosomal genes and histone H3 sequence data

The phylogenetic relationships of the members of the phylum Sipuncula are investigated by means of DNA sequence data from three nuclear markers, two ribosomal genes (18S rRNA and the D3 expansion fragment of 28S rRNA), and one protein-coding gene, histone H3. Phylogenetic analysis via direct optimization of DNA sequence data using parsimony as optimality criterion is executed for 12 combinations of parameter sets accounting for different indel costs and transversion/transition cost ratios in a sensitivity analysis framework. Alternative outgroup analyses are also performed to test whether they affected rooting of the sipunculan topology. Nodal support is measured by parsimony jackknifing and Bremer support values. Results from the different partitions are highly congruent, and the combined analysis for the parameter set that minimizes overall incongruence supports monophyly of Sipuncula, but nonmonophyly of several higher taxa recognized for the phylum. Mostly responsible for this is the split of the family Sipunculidae in three main lineages, with the genus Sipunculus being the sister group to the remaining sipunculans, the genus Phascolopsis nesting within the Golfingiiformes, and the genus Siphonosoma being associated to the Phascolosomatidea. Other interesting results are the position of Phascolion within Golfingiidae and the position of Antillesoma within Aspidosiphonidae. These results are not affected by the loci selected or by the outgroup chosen. The position of Apionsoma is discussed, although more data would be needed to better ascertain its phylogenetic affinities. Monophyly of the genera with multiple representatives (Themiste, Aspidosiphon, and Phascolosoma) is well supported, but not the monophyly of the genera Nephasoma or Golfingia. Interesting phylogeographic questions arise from analysis of multiple representatives of a few species.     

河南省西峡恐龙蛋化石DNA序列数据的再分析

利用ＩＮＴＥＲＮＥＴ网络上ＢＬＡＳＴ服务器和ＦＡＳＴＡ服务器程序对文献中发表的西峡县恐龙蛋化石的ＤＮＡ序列数据进行了序列数据库的类似性检索和分子系统学分析,证实克隆ＤＡ１８Ｓｌ和ＤＡ１８Ｓ７分别属于真菌和植物１８ＳｒＤＮＡ。文中还就在分子序列水平上对古ＤＮＡ的甄别与鉴定进行了讨论。     

“Missing” protists: a molecular prospective

Molecular ecology methods based on 18S rRNA amplification and sequencing have revealed an astounding diversity of microbial eukaryotes in every environment sampled so far. This is certainly true of new species and genera, as essentially every new survey discovers a wealth of novel diversity at this level. This is almost certain for taxa that are higher in taxonomic hierarchy, as many molecular surveys reported novel clades within established protistan phyla, with some of these clades repeatedly confirmed by subsequent studies. It may also be that the molecular approaches discovered several lineages of the highest taxonomic order, but this claim has not been vigorously verified as yet. Overall, the field of protistan diversity remains in its infancy. The true scale of this diversity is unknown, and so are the distribution of this diversity, its patterns, spatial and temporal dynamics, and ecological role. The sampled diversity appears to be just the tip of the iceberg, and this offers outstanding opportunities for microbial discovery for the purposes of both basic and applied research. Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner.     

江西武夷山发现缅甸钝头蛇

2014年8月,在江西武夷山国家级自然保护区采集到3号蛇类标本,基于形态学比较,并结合线粒体细胞色素b基因（Cyt b）序列的分子系统关系重建,确定这3号标本为缅甸钝头蛇（Pareas hamptoni）,为江西省蛇类分布新记录种。