77 resultados para small subunit ribosomal RNA


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Strains belonging to two novel yeast species, Candida bromeliacearum and Candida ubatubensis, were isolated from the bromeliad tank of Canistropsis seidelii (Bromeliaceae) in a sandy coastal plain (restinga) ecosystem site in an Atlantic rainforest of south-eastern Brazil. These species were genetically distinct from all other currently accepted ascomycetous yeasts, based on sequence divergence in the D1/D2 domains of the large-subunit rDNA and in the small-subunit rDNA. The species occupy basal positions in the Metschnikowiaceae clacle. The type strains are Candida bromeliacearum UNESP 00-103(T) (=CBS 10002(T) = NRRL Y-27811(T)) and Candida ubatubensis UNESP 01-247R(T) (=CBS 10003(T) = NRRL Y-27812(T)).

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To study the role played by acetate metabolism during high-cell-density growth of Escherichia coli cells, we constructed isogenic null mutants of strain W3100 deficient for several genes involved either in acetate metabolism or the transition to stationary phase. We grew these strains under identical fed-batch conditions to the highest cell densities achievable in 8 h using a predictive-plus-feedback-controlled computer algorithm that maintained glucose at a set-point of 0.5 g/l, as previously described. Wild-type strains, as well as mutants lacking the sigma(s) subunit of RNA polymerase (rpoS), grew reproducibly to high cell densities (44-50 g/l dry cell weights, DCWs). In contrast, a strain lacking acetate kinase (ackA) failed to reach densities greater than 8 g/l. Strains lacking other acetate metabolism genes (pta, acs, poxB, iciR, and fadR) achieved only medium cell densities (15-21 g/l DCWs). Complementation of either the acs or the ackA mutant restored wild-type high-cell-density growth, on a dry weight basis, poxB and fadR strains produced approximately threefold more acetate than did the wild-type strain. In contrast, the pta, acs, or rpoS strains produced significantly less acetate per cell dry weight than did the wild-type strain. Our results show that acetate metabolism plays a critical role during growth of E. coli cultures to high cell densities. They also demonstrate that cells do not require the sigma(s) regulon to grow to high cell densities, at least not under the conditions tested.

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The first quantitative analysis of phylogenetic relationships of green lacewings (Chrysopidae) is presented based on DNA sequence data. A single nuclear and two mitochondrial genes are used in the analysis: carbomoylphosphate synthase (CPS) domain of carbamoyl-phosphate synthetase-aspartate transcarbamoylase-dihydroorotase (CAD) (i.e. rudimentary locus), large subunit ribosomal gene (16S) and cytochrome oxidase I (COI). This study represents the first use of the CAD gene to investigate phylogenetic relationships of the lacewings. DNA sequences for 33 chrysopid species from 18 genera, representing all subfamilies and tribes, were compared with outgroups sampled from families Hemerobiidae, Osmylidae and Polystoechotidae. Parsimony analyses of the combined data set recovered all of the previously established subfamilial and tribal groups as monophyletic clades (although relatively weakly supported) except Apochrysinae sensu lato. The enigmatic Nothancyla verreauxi Navas has historically been difficult to place in a subfamily group based on morphological characteristics; molecular data presented herein do not adequately resolve this problem.

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The microorganisms are essential components in the maintenance of the biological and physicochemical balance of the soil. They exert important function including the degradation of residues of plants and animals and the release of nutrients in the alimentary chain. This work had as objective to compare the microbiota of a soil under bush covering (SMS) and other cropped with vegetables (SHC), suppressive or not it Rhizoctonia solani. Total microbial community DNA was extracted of soils, amplification for PCR of the genes 16S rDNA, inserted into pGEM (R)-T cloning vector and sequencing of the genes of the ribosomal RNA. The analysis of the results demonstrated that this methodology was efficient for evaluation of bacteria in ground. In the bush soil suppressive the microorganisms more found belonged to the phyla of the Acidobacterias, Verrucomicrobia and Actinobacterias and in the soil cultivated with vegetables the biggest frequency was of organisms pertaining to the phyla of the Proteobacterias, Firmicutes and Bacteroidetes.

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We analyze the chromosomal location of 5S rDNA clusters in 29 species of grasshoppers belonging to the family Acrididae. There was extensive variation among species for the number and location of 5S rDNA sites. Out of 148 sites detected, 75% were proximally located, 21.6% were interstitial, and only 3.4% were distal. The number of 5S rDNA sites per species varied from a single chromosome pair (in six species) to all chromosome pairs (in five species), with a range of intermediate situations. Thirteen chromosomes from eight species carried two 5S rDNA clusters. At intraspecific level, differences among populations were detected in Eyprepocnemis plorans, and some heteromorphisms have also been observed in some species. Double FISH for 5S rDNA and H3 histone gene DNA, performed on 17 of these 29 species, revealed that both markers are sometimes placed in a same chromosome but at different location, whereas they appeared to co-localize in five species (Calliptamus barbarus, Heteracris adpersa, Aiolopus strepens, Oedipoda charpentieri and O. coerulescens). Double fiber-FISH in A. strepens and O. coerulescens showed that the two DNAs are closely interspersed with variable relative amounts of both classes of DNA. Finally, no correlation was observed between the number of 5S and 45S rDNA clusters in 23 species where this information was available. These results are discussed in the light of possible mechanisms of spread that led to the extensive variation in the number of clusters observed for both rDNA types in acridid grasshoppers. © 2011 Springer Science+Business Media B.V.

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Among the most important diseases affecting Eucalyptus is Mycosphaerella Leaf Disease (MLD) caused by Mycosphaerella spp. and Teratosphaeria spp. MLD has led to significant losses in eucalypt plantations in the South and Southeast Region of Brazil, as well as in several countries such as Portugal, Spain, South Africa and Australia. Symptoms of MLD include localized necrotic spots, early defoliation in juvenile plants, stem cankers, early death of branches, and in some cases, atrophy and death. In the present study, single spore isolations from leaves of E. globulus from five locations in Brazil allowed the differentiation of species of Mycosphaerella and Teratosphaeria based on ascospore germination and growth in culture. These isolates were also subjected to sequence analysis of the ribosomal RNA internal transcribed spacer regions, which allowed their identification to species level. The results of this study showed that six species of Mycosphaerella and four species of Teratosphaeria were associated with leaves showing symptoms of MLD in E. globulus plantations in various locations of Brazil. © 2013 KNPV.

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Background: In a previous report, it was shown that Toll-like receptor (TLR) 2 knockdown modulates interleukin (IL)-6 and IL-8 but not the chemokine CXCL12, an important mediator with inflammatory and proangiogenic effects, in human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF). This study investigates whether knocking down two important TLR adaptor molecules, such as myeloid differentiation protein 88 (MyD88) and TRIF-related adaptor molecule (TRAM), could affect mRNA expression of IL-6, IL-8, and CXCL12 in HGF and HPDLF. Methods: After small interfering (si) RNA-mediated silencing of MyD88 or TRAM, HGF and HPDLF were stimulated with Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) or two synthetic ligands of TLR2 (Pam2CSK4 and Pam3CSK4) for 6 hours. IL-6, IL-8, and CXCL12 mRNAs were evaluated by quantitative polymerase chain reaction. Results: Knockdown of MyD88 or TRAM partially impaired the IL-8 mRNA upregulation in both fibroblast subpopulations. Similarly, IL-6 upregulation was partially prevented by siMyD88 or siTRAM in HGF stimulated with Pg LPS, as well as in both fibroblast subtypes challenged with Pam2CSK4. Conversely, constitutive CXCL12 mRNA levels were upregulated by MyD88 or TRAM knockdown in non-stimulated cells. Conclusions: These results suggest that TLR adaptor molecules knockdown, such as MyD88 or TRAM, can decrease IL-6 and IL-8 mRNA and increase CXCL12 mRNA expression in HGF and HPDLF. This can be an important step for better understanding the mechanisms that control the inflammatory cytokine and chemokine expression, which in turn contributes to periodontal pathogenesis.

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Phylogenetic approaches based on mitochondrial DNA variation (fragments of Cyt B and 16S ribosomal RNA) have revealed Triatoma sherlocki as the most recent species addition to the Triatoma brasiliensis species complex; a monophyletic group which includes T. brasiliensis, Triatoma melanica, and Triatoma juazeirensis. T. sherlocki is the most differentiated among all species of this complex: it is unable to fly, possesses longer legs than the other members, and has reddish tonality in some parts of its exochorion. We question whether these species are reproductively compatible because of this pronounced morphological differentiation, and therefore, we present a series of cross breeding experiments that test compatibility between T. sherlocki and other members of the T. brasiliensis complex. We extended our analyses to include crosses between T. sherlocki and Triatoma lenti, because the latter has been suggested as a possible member of this complex. T. sherlocki male. ×. T. lenti female pairs failed to produce hybrids. All other crosses of T. sherlocki and members of T. brasiliensis species complex, as well as backcrosses, produced viable offspring through the third generation. This study stresses the importance of searching for the features that may isolate members of the T. brasiliensis species complex. © 2013 Elsevier B.V.