台湾乳白蚁与赭黄乳白蚁的异名关系---基于形态与分子特征的分析(等翅目：鼻白蚁科）

乳白蚁属Coptotermes是鼻白蚁科Rhinotermitidae最具经济意义的属之一,其中的台湾乳白蚁Coptotermes formosanus Shriaki分布广、适应性强,个体在不同种群以及不同巢龄间外部形态存在明显变异,已报道多个同物异名。本研究发现在模式产地重新采集到经形态学鉴定为赭黄乳白蚁Coptotermes ochraceus Ping et Xu的标本,其形态特征与台湾乳白蚁相似度较高,又以线粒体16S rRNA和CO II基因作为分子标记,将两者进行了序列比对,并与美国国立生物技术信息中心(NCBI)中台湾乳白蚁以及其他一些乳白蚁种类的相应序列一起进行了遗传差异比较和同源性分析。结果表明,台湾乳白蚁与赭黄乳白蚁16S rRNA和CO II序列的遗传差异均明显小于台湾乳白蚁与属内其它种之间的差异;在基于两种分子标记构建的支序图中,台湾乳白蚁和赭黄乳白蚁均聚为一支,并得到了很高的自展支持率。综合分子和形态两方面的证据,本研究建议赭黄乳白蚁为台湾乳白蚁的次异名。     

Coptotermes gestroi (Isoptera: Rhinotermitidae) in Brazil: possible origins inferred by mitochondrial cytochrome oxidase II gene sequences

The Asian subterranean termite, Coptotermes gestroi, originally from northeast India through Burma, Thailand, Malaysia, and the Indonesian archipelago, is a major termite pest introduced in several countries around the world, including Brazil. We sequenced the mitochondrial COII gene from individuals representing 23 populations. Phylogenetic analysis of COII gene sequences from this and other studies resulted in two main groups: (1) populations of Cleveland (USA) and four populations of Malaysia and (2) populations of Brazil, four populations of Malaysia, and one population from each of Thailand, Puerto Rico, and Key West (USA). Three new localities are reported here, considerably enlarging the distribution of C.?gestroi in Brazil: Campo Grande (state of Mato Grosso do Sul), Itajaí (state of Santa Catarina), and Porto Alegre (state of Rio Grande do Sul).     

Phylogeography illuminates maternal origins of exotic Coptotermes gestroi (Isoptera: Rhinotermitidae)

Coptotermes gestroi, the Asian subterranean termite (AST), is an economically important structural and agricultural pest that has become established in many areas of the world. For the first time, phylogeography was used to illuminate the origins of new found C. gestroi in the US Commonwealth of Puerto Rico; Ohio, USA; Florida, USA; and Brisbane, Australia. Phylogenetic relationships of C. gestroi collected in indigenous locations within Malaysia, Thailand, and Singapore as well as from the four areas of introduction were investigated using three genes (16S rRNA, COII, and ITS) under three optimality criteria encompassing phenetic and cladistic assumptions (maximum parsimony, maximum likelihood, and neighbor-joining). All three genes showed consistent support for a close genetic relationship between C. gestroi samples from Singapore and Ohio, whereas termite samples from Australia, Puerto Rico, and Key West, FL were more closely related to those from Malaysia. Shipping records further substantiated that Singapore and Malaysia were the likely origin of the Ohio and Australia C. gestroi, respectively. These data provide support for using phylogeography to understand the dispersal history of exotic termites. Serendipitously, we also gained insights into concerted evolution in an ITS cluster from rhinotermitid species in two genera.     

The complete mitogenome of the Formosan termite, Coptotermes formosanus Shiraki

The Formosan termite Coptotermes formosanus Shiraki is a well-known invasive pest that causes severe damage to wooden structures in many parts of the world. Although several studies examined its phylogeographic patterns using a few mitochondrial genes, the phylogenetic relationships among C. formosanus are poorly understood because of the small number of mutations known among its mitochondrial genes. To provide a useful genetic tool for further analyses, we analyzed the complete mitochondrial genome sequence of C. formosanus using specimens collected from three isolated islands in the Ryukyu Archipelago of Japan. The circular mitogenome of these termites consisted of genes encoding 22 transfer RNAs, two ribosomal RNAs, and 13 mitochondrial proteins, as is the case for most animal mitochondrial genomes. The G + C content was 34.1%, and the total length varied slightly between 16,234 and 16,236 base pairs. The complete mitochondrial genomes of the three populations were more than 99.9% identical to each other and showed differences at six nucleotide positions. The COII, 12S rRNA, and 16S rRNA genes that are commonly used for phylogenetic analyses revealed only one substitution or no substitutions. The mitogenome sequences determined here should contribute to the design of new molecular markers for the clarification of the historical distribution process of C. formosanus and for further phylogenetic analyses with this and related termite species.     

Mitochondrial sequence evolution in spiders: intraspecific variation in tRNAs lacking the TPsiC Arm

Analyses of mitochondrial DNA sequences from three species of Habronattus jumping spiders (Chelicerata: Arachnida: Araneae) reveal unusual inferred tRNA secondary structures and gene arrangements, providing new information on tRNA evolution within chelicerate arthropods. Sequences from the protein-coding genes NADH dehydrogenase subunit 1 (ND1), cytochrome oxidase subunit I (COI), and subunit II (COII) were obtained, along with tRNA, tRNA, and large-subunit ribosomal RNA (16S) sequences; these revealed several peculiar features. First, inferred secondary structures of tRNA and, likely, tRNA, lack the TPsiC arm and the variable arm and therefore do not form standard cloverleaf structures. In place of these arms is a 5-6-nt T arm-variable loop (TV) replacement loop such as that originally described from nematode mitochondrial tRNAs. Intraspecific variation occurs in the acceptor stem sequences in both tRNAs. Second, while the proposed secondary structure of the 3' end of 16S is similar to that reported for insects, the sequence at the 5' end is extremely divergent, and the entire gene is truncated about 300 nt with respect to Drosophila yakuba. Third, initiation codons appear to consist of ATY (ATT and ATC) and TTG for ND1 and COII, respectively. Finally, Habronattus shares the same ND1-tRNA-16S gene arrangement as insects and crustaceans, thus illustrating variation in a tRNA gene arrangement previously proposed as a character distinguishing chelicerates from insects and crustaceans.     

Molecular differentiation of the microgastrine species commonly found in paddy fields from Southeast Asia,with additional data on their phylogeny （Hymenoptera：Braconidae）

Partial DNA sequences of three genes, that is, mitochondrial large ribosomal subunit (16S), nuclear large ribosomal subunit (28S D2) and mitochondrial NADH1 dehydrogenase (NADH1) gene, were sequenced from different microgas trine species(Braconidae: Microgastrinae) collected fresh from paddy fields. The DNA sequences were used to determine the extent of sequence variation among species in order to evaluate the specific status of each species. Cladistic analysis was also used to infer a phylogenetic relationship among these species. The results showed that sequence divergence among species of the same genus Cotesia was much lower than those among different genera, such as Cotesia, Exoryza and Apanteles; the sequence similarity of 16S rDNA and NADH 1 genes between Cotesia sp. and C. chilonis was higher than that between C. sp. and C. ruficrus.Phylogenetic analyses suggested that four species of Cotesia were always grouped in the same clade regardless of using different analysis methods; Cotesia sp. and C. chilonis are more closely related to each other than to C. ruficrus, different from previous morphological results. Additionally, sequence analyses indicated that NADH1 gene has more parsimony informative characters than 28S rDNA D2 and 16S rDNA at the species-level analysis,indicating that NADH1 gene might be a useful marker for species-level analysis.     

Nucleotide sequence and evolution of the 18S ribosomal RNA gene in maize mitochondria.

The nucleotide sequence of the gene coding for the 18S ribosomal RNA of maize mitochondria has been determined and a model for the secondary structure is proposed. Dot matrix analysis has been used to compare the extent and distribution of sequence similarities of the entire maize mitochondrial 18S rRNA sequence with that of 15 other small subunit rRNA sequences. The mitochondrial gene shows great similarity to the eubacterial sequences and to the maize chloroplast, and less similarity to mitochondrial rRNA genes in animals and fungi. We propose that this similarity is due to a slow rate of nucleotide divergence in plant mtDNA compared to the mtDNA of animals. Sequence comparisons indicate that the evolution of the maize mitochondrial 18S, chloroplast 16S and nuclear 17S ribosomal genes have been essentially independent, in spite of evidence for DNA transfer between organelles and the nucleus.     

Next generation sequencing from Hepatozoon canis (Apicomplexa: Coccidia: Adeleorina): Complete apicoplast genome and multiple mitochondrion-associated sequences

Extrachromosomal genomes of the adeleorinid parasite Hepatozoon canis infecting an Israeli dog were investigated using next-generation and standard sequencing technologies. A complete apicoplast genome and several mitochondrion-associated sequences were generated. The apicoplast genome (31,869?bp) possessed two copies of both large subunit (23S) and small subunit (16S) ribosomal RNA genes (rDNA) within an inverted repeat region, as well as 22 protein-coding sequences, 25 transfer RNA genes (tDNA) and seven open reading frames of unknown function. Although circular-mapping, the apicoplast genome was physically linear according to next-generation data. Unlike other apicoplast genomes, genes encoding ribosomal protein S19 and tDNAs for alanine, aspartic acid, histidine, threonine and valine were not identified. No complete mitochondrial genome was recovered using next-generation data or directed PCR amplifications. Eight mitochondrion-associated (215–3523?bp) contigs assembled from next-generation data encoded a complete cytochrome c oxidase subunit I coding sequence, a complete cytochrome c oxidase subunit III coding sequence, two complete cytochrome B coding sequences, a non-coding, pseudogene for cytochrome B and multiple fragmented mitochondrial rDNA genes (SSUA, SSUB, SSUD, LSUC, LSUG, RNA6, RNA10, RNA14, RNA18). The paucity of NGS reads generating each of the mitochondrion-like sequences suggested that a complete mitochondrial genome at typically high copy number was absent in H. canis. In contrast, the complete nuclear rDNA unit sequence of H. canis (18S rDNA to 28S rDNA, 6977?bp) had >1000-fold next-generation coverage. Multiple divergent (from 93.6% to 99.9% pairwise identities) nuclear 18S rDNA contigs were generated (three types with 10 subtypes total). To our knowledge this is the first apicoplast genome sequenced from any adeleorinid coccidium and the first mitochondrion-associated sequences from this serious pathogen of wild and domestic canids. These newly generated sequences may provide useful genetic loci for high-resolution species-level genotyping that is currently impossible using existing nuclear rDNA targets.     

Phylogeny of Australian Coptotermes (Isoptera: Rhinotermitidae) species inferred from mitochondrial COII sequences

Six Australian species of Coptotermes are traditionally recognized, but recent cuticular hydrocarbon studies suggest that some of these may represent more than one species. An understanding of the phylogenetic diversity of Australian Coptotermes, particularly the pest species, is likely to be important for the improvement of termite management strategies. A study of phylogenetic relationships among species of this genus was performed, based on the mitochondrial cytochrome oxidase (COII) gene, comparing the data with recent data from Asian species. Representatives of the species C. lacteus (Froggatt), C. frenchi Hill and C. michaelseni Silvestri were each found to form closely related monophyletic groups, however representatives of C. acinaciformis (Froggatt) were not. For C. acinaciformis, representatives from northern mound-building populations were found to form a distinct group to southern, tree-nesting forms. Among southern C. acinaciformis, two Western Australian representatives were found to be divergent from other populations. The results suggest that C. acinaciformis probably represents a complex of species rather than one, as has been suggested previously. One unidentified Coptotermes sp. taxon from Melbourne was found to be divergent from other taxa. Notably, some Australian species were more closely related to Asian species than other Australian species.     

Assessing Nuclear and Mitochondrial DNA Sequence Variation Within Steinernema (Rhabditida: Steinernematidae)

DNA sequence analysis was used to characterize the nuclear ribosomal DNA ITS1 region and a portion of the COII and 16S rDNA genes of the mitochondrial genome from Steinernema entomopathogenic nematodes. Nuclear ITS1 nucleotide divergence among seven Steinernema spp. ranged from 6 to 22%, and mtDNA divergence among five species ranged from 12 to 20%. No intraspecific variation was observed among three S. feltiae strains. Phylogenetic analysis of both nuclear and mitochondrial DNA sequences confirms the existing morphological relationships of several Steinernema species. Both the rDNA ITS1 and mtDNA sequences were useful for resolving relationships among Steinernema taxa.     

Sequence analysis of ribosomal and mitochondrial genes of the giant liver fluke Fascioloides magna (Trematoda: Fasciolidae): intraspecific variation and differentiation from Fasciola hepatica

Complete sequences of ribosomal and mitochondrial genes of the giant liver fluke Fascioloides magna are presented. In particular, small subunit (18S) and internal transcribed spacers (ITS1 and ITS2) of the ribosomal gene (rDNA), as well as cytochrome c oxidase subunit I (cox1) and nicotinamide dehydrogenase subunit I (nad1) of the mitochondrial DNA (mtDNA), were analyzed. The 18S and ITS sequences were compared with previously published sequences of the liver fluke Fasciola hepatica. Fixed interspecific genetic differences were determined that allow molecular differentiation of F. magna and F. hepatica using either the PCR-RFLP method or PCR amplification of species-specific DNA regions. Additionally, intraspecific sequence polymorphism of the complete cox1 and nad1 mitochondrial genes in geographically distinct F. magna populations was determined. Based on the sequence divergences, short (< 500 bp) variable regions suitable for broader biogeographical studies of giant liver fluke were designed.     

Homology between the ribosomal DNA of Escherichia coli and mitochondrial DNA preparations of maize is principally to sequences other than mitochondrial rRNA genes

E. coli ribosomal DNA has been used to probe maize mitochondrial DNA. It hybridizes primarily with chloroplast ribosomal DNA sequences and with fungal and bacterial sequences which may contaminate the mtDNA preparations. It also hybridizes to the chloroplast 16S ribosomal RNA gene sequence present in the mitochondrial genome (1) as well as to the mitochondrial 18S ribosomal RNA gene sequence. Weak sequence homology was detected between E. coli rDNA and the mitochondrial 26S ribosomal RNA gene.     

Cuticular permeability of two species of Coptotermes Wasmann (Isoptera: Rhinotermitidae)

Cuticular permeability (CP) values of worker and soldier castes of Coptotermes formosanus Shiraki and Coptotermes vastator Light were determined using gravimetric techniques. Comparisons were made between castes, species, and between colonies of C. formosanus and C. vastator. CP values did not differ among either species or colony, however they did differ between castes. Data reported here and that of established data in the literature for C. formosanus are inconsistent, with the current report having values as small as half that of previously published data. Examining mean CP data by colony indicated that there is a range for Coptotermes spp. termites, from 6.84+/-1.2 to 25.61+/-1.49 microg H(2)Ocm(-2)mmHg(-1)h(-1) dependent upon caste. A novel method of examining intercaste CP variability is the use of worker:soldier CP ratios. Ratios for C. formosanus were consistent between the current study and previous reports. Mean percentage total body water (%TBW) lost at the time of death was 33.75+/-1.15% (soldiers) and 54.24+/-1.43% (workers) for C. formosanus, and 37.69+/-3.31% (soldiers) and 52.87+/-3.65% (workers) for C. vastator. Consistently, %TBW (and fresh mass) was greater in worker than in soldier castes. These data suggest the use of water storage mechanisms in worker termites, as shown for other rhinotermitids.     

Interspecific competition and territory defense mechanisms of Coptotermes formosanus and Coptotermes gestroi (Isoptera: Rhinotermitidae)

Coptotermes formosanus Shiraki and C. gestroi (Wasmann) are the most widely distributed species of the genus and occur sympatrically in the subtropics. Results of two bioassays in the current study showed that C. gestroi was more aggressive than C. formosanus. In the petri-dish bioassays, C. gestroi won most of the agonistic encounters over C. formosanus. In the two-dimensional foraging arena bioassays, over 73% tunnel interceptions observed in the 18 replications were caused by progressing tunnels of C. gestroi encountering the tunnels of C. formosanus. Tunnel interception of the two species resulted in minor agonistic interactions. Both species quickly buried the connected tunnel at multiple locations. Termite cadavers resulting from agonistic behavior appeared to have induced sand deposition that resulted in tunnel blockages and deterred reopening of these blockages. Sealing individual tunnels in response to encounters with other species acts to prevent further agonism and mortality, and on a broad scale, the aggregate of such blocked tunnels may come to define the borders between adjacent colonies.     

The complete sequence of the mitochondrial genome of the Chinook salmon, Oncorhynchus tshawytscha

The complete sequence of the mitochondrial genome of Chinook salmon, Oncorhynchus tshawytscha, has been determined. The circular genome consisting of 16,644 base pairs encodes thirteen proteins, the 12S and 16S ribosomal RNAs, and 22 transfer RNAs. These genes are ordered in the same way as most other vertebrates. The nucleotide and amino acid sequences of the ribosomal RNAs and the thirteen protein-coding genes were compared with those of other salmonids such as Oncorhynchus mykiss, Salmo salar, Salvelinus fontinalis, Salvelinus alpinus and Coregonus lavaretus. The sequence features of the control region (D-loop), the origin of L-strand replication and a putative peptide codified by the 16S mitochondrial RNA are described and discussed.     

Maxicircle (mitochondrial) genome sequence (partial) of Leishmania major: gene content, arrangement and composition compared with Leishmania tarentolae

We report 8420 bp of DNA sequence data from the maxicircle (mitochondrial) genome of Leishmania major (MHOM/SU/73/5ASKH), a much larger portion of this genome than has been reported previously from any Leishmania species infecting humans. This region contains 10 partial and complete genes: 5 protein-encoding genes (COII, COIII, ND1, ND7 and Cyt b); two ribosomal RNA subunits (12S and 9S) and three unidentified open reading frames (MURF1, MURF4 (ATPase6) and MURF5), as in the lizard-infecting species L. tarentolae. The genes from L. major exhibit 85-87% identity with those of L. tarentolae at the nucleotide level and 71-94% identity at the amino acid level. Most differences between sequences from the two species are transversions. The gene order and arrangement within the maxicircle of L. major are similar to those in L. tarentolae, but base composition and codon usage differ between the species. Codons assigned for initiation for protein-coding genes available for comparison are similar in five genes in the two species. Pre-editing was identified in some of the protein-coding genes. Short intergenic non-coding regions are also present in L. major as they are in L. tarentolae. Intergenic regions between 9S rRNA and MURF5, MURF1 and ND1 genes are G+C rich and considered to be extensive RNA editing regions. The RNA editing process is likely to be conserved in similar pattern in L. major as in L. tarentolae.