Molecular phylogenic location of the Plagiorchis muris (Digenea, Plagiorchiidae) based on sequences of partial 28S D1 rDNA and mitochondrial cytochrome C oxidase subunit I

To determine the molecular phylogenic location of Plagiorchis muris, 28S D1 ribosomal DNA (rDNA) and mitochondrial cytochrome C oxidase subunit I (mtCOI) were sequenced and compared with other trematodes in the family Plagiorchiidae. The 28S D1 tree of P. muris was found to be closely related to those of P. elegans and other Plagiorchis species. And, the mtCOI tree also showed that P. muris is in a separate clade with genus Glypthelmins. These results support a phylogenic relationship between members of the Plagiorchiidae, as suggested by morphologic features.     

Molecular data confirm the validity of the Portuguese blenny (Parablennius ruber, Valenciennes, 1836) and its presence in Western Europe

DNA sequence analysis confirms the distinction between Parablennius ruber and Parablennius gattorugine , simultaneously validating the presence of the former species in Western Europe where it has been reported for >150 years. A possible scenario involving speciation of P. ruber at the Azores and subsequent transport of larvae to Europe, a process that may be still occurring nowadays, could explain this pattern of occurrence.     

食肉目猫科物种的系统发育学研究概述

猫科动物(Felidae)是食肉目中肉食性最强的一科, 其中许多成员是人们最熟悉、最引人注目的动物, 也是各地的顶级食肉动物。目前37个现存猫科物种中有36个已经被列为濒危和稀有对象。食肉目猫科物种的进化历史是一个快速辐射和较近时期发生的物种形成事件, 使得猫科物种之间系统发育关系的重建非常困难, 一直处于广泛争论的状态。构建可靠的猫科系统发育关系, 具有重要的进化理论意义和保护生物学价值。文章对猫科物种的系统发育学研究进展, 包括来自于形态学特征、细胞学和分子生物学方面的证据做简要概述, 并提出目前研究中存在的问题。以期对今后猫科物种的系统发育方面的进一步研究工作具有指导意义, 并为该类群的生物多样性资源保护提供科学依据。     

Chloroplast DNA‐based studies in molecular ecology may be compromised by nuclear‐encoded plastid sequence

Ongoing genetic transfer from mitochondria and plastids into the nucleus is a well‐documented fact. While in metazoan molecular ecology the need for surveillance against pseudogene‐mediated artefacts when analysing mtDNA sequences is commonly accepted, no comparable measurements have been established for plastid‐based studies. We highlight the impact and management of nuclear mitochondrial insertions, argue that nuclear plastid sequences represent an underestimated but major factor in plant molecular ecology, and discuss potential avenues of remedy in chloroplast studies.     

Origins of the new allopolyploid species Senecio cambrensis (asteraceae) and its relationship to the canary islands endemic Senecio teneriffae

The distribution of a 330 bp cpDNA insertion was reexamined in British material of Senecio cambrensis (2n = 6x = 60), its two putative parental taxa, S. squalidus (2n = 2x = 20) and S. vulgaris (2n = 4x = 40), and the closely related Canary Islands' endemic S. teneriffae (2n = 6x = 60). This formed part of a test of the hypothesis that the Welsh form of S. cambrensis is derived from introduced S. teneriffae rather than having originated in Wales via allopolyploidy as previously supposed. It was established that the 330 bp insertion was carried by all plants of Welsh S. cambrensis and also S. teneriffae, but was absent from the cpDNA of Edinburgh S. cambrensis and all plants of British S. squalidus and S. vulgaris var. vulgaris surveyed. However, two of 19 individuals tested of S. vulgaris var. hibernicus also possessed the cpDNA insertion, indicating that it is present in British material of S. vulgaris, although at low frequency. The close similarity between S. teneriffae and S. cambrensis, especially the Welsh form of S. cambrensis, was confirmed by the results of a restriction analysis of rDNA, and also morphometric and crossing studies. However, isozyme analysis showed that S. teneriffae is monomorphic for βEST-3 and ACO-1 phenotypes that are not present in Welsh and Edinburgh S. cambrensis, nor in S. squalidus and S. vulgaris material surveyed. It is concluded that S. teneriffae and S. cambrensis are two closely related allohexaploid taxa that have very similar, but different origins. It is postulated that whereas S. cambrensis (in Wales and Edinburgh) is the allohexaploid of S. vulgaris and S. squalidus, S. teneriffae is possibly the allohexaploid of S. vulgaris and S. glaucus, the latter being a diploid species closely related to S. squalidus.     

EFFECTS OF INTRINSIC AND EXTRINSIC FACTORS ON POPULATION FRAGMENTATION IN THREE SPECIES OF NORTH AMERICAN MINNOWS (TELEOSTEI: CYPRINIDAE)

Geographic patterns of genetic variation (mitochondrial DNA [mtDNA] and allozymes) were used to examine effects of intrinsic characteristics (e.g., vagility, habitat specificity, and reproductive behaviors) and extrinsic factors (e.g., climatic and geological history) on population fragmentation. The three species of cyprinid fishes examined (Tiaroga cobitis, Meda fulgida, and Agosia chrysogaster) occupied similar historical ranges within the lower Colorado River drainage, but differ in intrinsic characteristics conducive to population fragmentation. Relationships among populations were similar across species, reflecting common historical influences, but results indicate the distribution of variation among species is strongly affected by intrinsic characteristics. Variation within two species (T. cobitis and M. fulgida) is subdivided among populations, suggesting little gene flow among rivers. In contrast, similarity of A. chrysogaster populations throughout the Gila River drainage supports the hypothesis that levels of gene flow are high for this species. Levels of mtDNA divergence were much higher than expected for both T. cobitis and A. chrysogaster suggesting long-term isolation of geographic regions. These results indicate that both long-term and short-term extrinsic factors have shaped basic patterns of variation within these fishes; however, the intrinsic characteristics of each species have strongly affected the population genetic structure of these fishes.     

The Most Redundant Sequences in Human CpG Island Library Are Derived from Mitochondrial Genome

An altered pattern of epigenetic modifications, such as DNA methylation and histone modification, is critical to many common human diseases, including cancer. Recently, mitochondrial DNA (mtDNA) was reported to be associated with tumorigenesis through epigenetic regulation of methylation patterns. One of the promising approaches to study DNA methylation and CpG islands (CGIs) is sequencing and analysis of clones derived from the physical library generated by methyl-CpG-binding domain proteins and restriction enzyme MseI. In this study, we observed that the most redundant sequences of 349 clones in a human CGI library were all generated from the human mitochondrial genome. Further analysis indicated that there was a 5,845-bp DNA transfer from mtDNA to chromosome 1, and all the clones should be the products of a 510-hp MseI fragment, which contained a putative CGI of 270 bp. The 510-bp fragment was annotated as part of cytochrome c oxidase subunit Ⅱ (COXⅡ), and phylogenetic analysis of homologous sequences containing COXII showed three DNA transfer events from mtDNA to nuclear genome, one of which underwent secondary transfer events between different chromosomes. These results may further our understanding of how the mtDNA regulates DNA methylation in the nucleus.