74 research outputs found

    ПРОБЛЕМА СОПРЯЖЕННОСТИ СЛОВ В ДРЕВЕСНОМ ПРОИЗВЕДЕНИИ СВОБОДНЫХ ГРУПП С ЦИКЛИЧЕСКИМ ОБЪЕДИНЕНИЕМ

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    In the work positively with the problem of the conjugation words in a tree product of free groups associated with cyclic subgroups. This work is a generalization of the well-known results of Lipschutz S. for a free product of two free groups with cyclic amalgamation.When solving the main problem it is proved the solvability of the problem of intersection of finite generated subgroup of this group with a cyclic subgroup of the factor group and the problem of the intersection of the co-set of finite generated by subgroup with a cyclic subgroup of the factor group.  В работе положительно решена проблема сопряженности слов в древесном произведении свободных групп с ассоциированными циклическими подгруппами. Представленный результат является обобщением известного результата С.Липшуца для свободного произведения двух свободных групп с циклическим объединением. При решении основной проблемы доказывается разрешимость проблемы пересечения конечно порожденной подгруппы данного класса групп с циклической подгруппой, принадлежащей сомножителю основной группы, а так же проблема пересечения смежного класса конечно порожденной подгруппы с циклической подгруппой, принадлежащей сомножителю.

    De novo sequencing and characterization of floral transcriptome in two species of buckwheat (Fagopyrum)

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    <p>Abstract</p> <p>Background</p> <p>Transcriptome sequencing data has become an integral component of modern genetics, genomics and evolutionary biology. However, despite advances in the technologies of DNA sequencing, such data are lacking for many groups of living organisms, in particular, many plant taxa. We present here the results of transcriptome sequencing for two closely related plant species. These species, <it>Fagopyrum esculentum </it>and <it>F. tataricum</it>, belong to the order Caryophyllales - a large group of flowering plants with uncertain evolutionary relationships. <it>F. esculentum </it>(common buckwheat) is also an important food crop. Despite these practical and evolutionary considerations <it>Fagopyrum </it>species have not been the subject of large-scale sequencing projects.</p> <p>Results</p> <p>Normalized cDNA corresponding to genes expressed in flowers and inflorescences of <it>F. esculentum </it>and <it>F. tataricum </it>was sequenced using the 454 pyrosequencing technology. This resulted in 267 (for <it>F. esculentum</it>) and 229 (<it>F. tataricum</it>) thousands of reads with average length of 341-349 nucleotides. <it>De novo </it>assembly of the reads produced about 25 thousands of contigs for each species, with 7.5-8.2× coverage. Comparative analysis of two transcriptomes demonstrated their overall similarity but also revealed genes that are presumably differentially expressed. Among them are retrotransposon genes and genes involved in sugar biosynthesis and metabolism. Thirteen single-copy genes were used for phylogenetic analysis; the resulting trees are largely consistent with those inferred from multigenic plastid datasets. The sister relationships of the Caryophyllales and asterids now gained high support from nuclear gene sequences.</p> <p>Conclusions</p> <p>454 transcriptome sequencing and <it>de novo </it>assembly was performed for two congeneric flowering plant species, <it>F. esculentum </it>and <it>F. tataricum</it>. As a result, a large set of cDNA sequences that represent orthologs of known plant genes as well as potential new genes was generated.</p

    The Chloroplast Genome Sequence of Mungbean (Vigna radiata) Determined by High-throughput Pyrosequencing: Structural Organization and Phylogenetic Relationships

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    Mungbean is an economically important crop which is grown principally for its protein-rich dry seeds. However, genomic research of mungbean has lagged behind other species in the Fabaceae family. Here, we reported the complete chloroplast (cp) genome sequence of mungbean obtained by the 454 pyrosequencing technology. The mungbean cp genome is 151 271 bp in length which includes a pair of inverted repeats (IRs) of 26 474 bp separated by a small single-copy region of 17 427 bp and a large single-copy region of 80 896 bp. The genome contains 108 unique genes and 19 of these genes are duplicated in the IR. Of these, 75 are predicted protein-coding genes, 4 ribosomal RNA genes and 29 tRNA genes. Relative to other plant cp genomes, we observed two distinct rearrangements: a 50-kb inversion between accD/rps16 and rbcL/trnK-UUU, and a 78-kb rearrangement between trnH/rpl14 and rps19/rps8. We detected sequence length polymorphism in the cp homopolymeric regions at the intra- and inter-specific levels in the Vigna species. Phylogenetic analysis demonstrated a close relationship between Vigna and Phaseolus in the phaseolinae subtribe and provided a strong support for a monophyletic group of the eurosid I

    Transcriptome Analysis of the Oriental Fruit Fly (Bactrocera dorsalis)

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    The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most economically important pests in the world, causing serious damage to fruit production. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its development and its ability to resist insecticides. Analysis of the B. dorsalis transcriptome and its expression profile data is essential to extending the genetic information resources on this species, providing a shortcut that will support studies on B. dorsalis.We performed de novo assembly of a transcriptome using short read sequencing technology (Illumina). The results generated 484,628 contigs, 70,640 scaffolds, and 49,804 unigenes. Of those unigenes, 27,455 (55.13%) matched known proteins in the NCBI database, as determined by BLAST search. Clusters of orthologous groups (COG), gene orthology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations were performed to better understand the functions of these unigenes. Genes related to insecticide resistance were analyzed in additional detail. Digital gene expression (DGE) libraries showed differences in gene expression profiles at different developmental stages (eggs, third-instar larvae, pupae, and adults). To confirm the DGE results, the expression profiles of six randomly selected genes were analyzed.This transcriptome greatly improves our genetic understanding of B. dorsalis and makes a huge number of gene sequences available for further study, including both genes of known importance and genes of unknown function. The DGE data provide comprehensive insight into gene expression profiles at different developmental stages. This facilitates the study of the role of each gene in the developmental process and in insecticide resistance

    Adaptation and Convergent Evolution within the Jamesonia-Eriosorus Complex in High-Elevation Biodiverse Andean Hotspots

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    The recent uplift of the tropical Andes (since the late Pliocene or early Pleistocene) provided extensive ecological opportunity for evolutionary radiations. We test for phylogenetic and morphological evidence of adaptive radiation and convergent evolution to novel habitats (exposed, high-altitude páramo habitats) in the Andean fern genera Jamesonia and Eriosorus. We construct time-calibrated phylogenies for the Jamesonia-Eriosorus clade. We then use recent phylogenetic comparative methods to test for evolutionary transitions among habitats, associations between habitat and leaf morphology, and ecologically driven variation in the rate of morphological evolution. Páramo species (Jamesonia) display morphological adaptations consistent with convergent evolution in response to the demands of a highly exposed environment but these adaptations are associated with microhabitat use rather than the páramo per se. Species that are associated with exposed microhabitats (including Jamesonia and Eriorsorus) are characterized by many but short pinnae per frond whereas species occupying sheltered microhabitats (primarily Eriosorus) have few but long pinnae per frond. Pinnae length declines more rapidly with altitude in sheltered species. Rates of speciation are significantly higher among páramo than non-páramo lineages supporting the hypothesis of adaptation and divergence in the unique Páramo biodiversity hotspot

    Deciduous Trees and the Application of Universal DNA Barcodes: A Case Study on the Circumpolar Fraxinus

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    The utility of DNA barcoding for identifying representative specimens of the circumpolar tree genus Fraxinus (56 species) was investigated. We examined the genetic variability of several loci suggested in chloroplast DNA barcode protocols such as matK, rpoB, rpoC1 and trnH-psbA in a large worldwide sample of Fraxinus species. The chloroplast intergenic spacer rpl32-trnL was further assessed in search for a potentially variable and useful locus. The results of the study suggest that the proposed cpDNA loci, alone or in combination, cannot fully discriminate among species because of the generally low rates of substitution in the chloroplast genome of Fraxinus. The intergenic spacer trnH-psbA was the best performing locus, but genetic distance-based discrimination was moderately successful and only resulted in the separation of the samples at the subgenus level. Use of the BLAST approach was better than the neighbor-joining tree reconstruction method with pairwise Kimura's two-parameter rates of substitution, but allowed for the correct identification of only less than half of the species sampled. Such rates are substantially lower than the success rate required for a standardised barcoding approach. Consequently, the current cpDNA barcodes are inadequate to fully discriminate Fraxinus species. Given that a low rate of substitution is common among the plastid genomes of trees, the use of the plant cpDNA “universal” barcode may not be suitable for the safe identification of tree species below a generic or sectional level. Supplementary barcoding loci of the nuclear genome and alternative solutions are proposed and discussed

    Chloroplast genomes: diversity, evolution, and applications in genetic engineering

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