Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Ying Yong Sheng Tai Xue Bao ; 27(1): 33-9, 2016 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-27228590

RESUMO

Taking four plant species, Caragana korshinskii, Salix psammophila, Hippophae rhamnides and Artemisia sphaerocephala, which were 3-4 years old and in vigorous growth period, as test materials, the anti-fracture forces of lateral-root branches and adjacent upper straight roots were measured with the self-made fixture and the instrument of TY 8000. The lateral-root branches were vital and the diameters were 1-4 mm. The results showed that the anti-fracture force and anti-fracture strength of lateral-root branches were lesser than those of the adjacent upper straight roots even though the average diameter of lateral-root branches was greater. The ratios of anti-fracture strength of lateral-root branches to the adjacent upper straight roots were 71.5% for C. korshinskii, 62.9% for S. psammophila, 45.4% for H. rhamnides and 35.4% for A. sphaerocephala. For the four plants, the anti-fracture force positively correlated with the diameter in a power function, while the anti-fracture strength negatively correlated with diameter in a power function. The anti-fracture strengths of lateral-root branches and adjacent upper straight roots for the four species followed the sequence of C. korshinskii (33.66 and 47.06 MPa) > S. psammophila (17.31 and 27.54 MPa) > H. rhamnides (3.97 and 8.75 MPa) > A. sphaerphala (2.18 and 6.15 MPa).


Assuntos
Artemisia/crescimento & desenvolvimento , Caragana/crescimento & desenvolvimento , Hippophae/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Salix/crescimento & desenvolvimento
2.
Ying Yong Sheng Tai Xue Bao ; 26(2): 411-8, 2015 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-26094454

RESUMO

This paper took four kinds of common soil and water conservation plants of the study area, Caragana microphylla, Salix psammophila, Artemisia sphaerocephala and Hippophae rhamnides at ages of 4 as the research object. Thirteen indicators, i.e., single shrub to reduce wind velocity ration, shelterbelt reducing wind velocity ration, community reducing wind velocity ration, taproot tensile strength, representative root constitutive properties, representative root elasticity modulus, lateral root branch tensile strength, accumulative surface area, root-soil interface sheer strength, interface friction coefficient, accumulative root length, root-soil composite cohesive, root-soil composite equivalent friction angle, reflecting the characteristics of windbreak and roots, were chose to evaluate the differences of foliage-root coupling soil-reinforcement and anti-erosion among four kinds of plants by analytic hierarchy process (AHP) under the condition of spring gale and summer rainstorm, respectively. The results showed the anti-erosion index of foliage-root coupling was in the sequence of S. psammophila (0.841) > C. microphylla (0.454) > A. sphaerocephala (-0.466) > H. rhamnides (-0.829) in spring gale, and C. microphylla (0.841) > S. psammophila (0. 474) > A. sphaerocephala (-0.470) > H. rhamnides (-0.844) in summer rainstorm. S. psammophila could be regarded as one of the most important windbreak and anti-erosion species, while C. microphylla could be the most valuable soil and water conservation plant for the study area.


Assuntos
Folhas de Planta/fisiologia , Raízes de Plantas/fisiologia , Solo , Artemisia , Caragana , Conservação dos Recursos Naturais , Hippophae , Salix , Estações do Ano , Vento
3.
Asian J Androl ; 15(4): 545-9, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23708455

RESUMO

To identify risk factors for HIV infection among men who have sex with men (MSM) and to provide a theoretical basis for prevention interventions. Between December 2011 and August 2012, a case-control study was conducted among MSM who underwent voluntary counselling and testing for HIV. Confirmed HIV-positive MSM were included in the case group, and HIV-negative MSM were included in the control group. Information on possible risk factors was collected by a survey questionnaire and a qualitative interview. The results of a conditional logistic regression showed that the following were influencing factors for HIV infection: average monthly income between 2001 and 3000 Yuan (odds ratio (OR)=6.341, 95% CI: 1.714-12.544), only sometimes using condoms when having anal sex with men in the last 6 months (OR=7.601, 95% CI: 1.359-23.083), having HIV-positive sex partners (OR=5.273, 95% CI: 1.572-17.691), rectal trauma with bleeding in the last 6 months (OR=2.947, 95% CI: 1.308-6.638), not using condoms at last sexual encounter (OR=1.278, 95% CI: 1.012-5.595), engaging in commercial sex (OR=5.925, 95% CI: 1.923-13.890) and having more than 16 sex partners in the last 6 months (OR=1.175, 95% CI: 1.021-1.353). These seven factors were the risk factors of HIV infection (OR>1). However, having anal sex less than 10 times in the previous 1 month (OR=0.002, 95% CI: 0.000-0.287) was a protective factor against HIV infection among MSM (OR<1), and insertive (OR=0.116, 95% CI: 0.000-0.236) (OR<1) anal intercourse influenced HIV infection. Interventions should be targeted at MSM whose average monthly income is between 2001 and 3000 Yuan, and who engage in commercial sex. In addition, the importance of using condoms at every sexual encounter should be emphasised in health education, as should the treatment of rectal trauma with bleeding. Finally, MSM should decrease the number of sex partners and frequency of anal sex to decrease the rate of HIV infection.


Assuntos
Infecções por HIV/etnologia , Homossexualidade Masculina/estatística & dados numéricos , Doenças Virais Sexualmente Transmissíveis/etnologia , Adolescente , Adulto , Estudos de Casos e Controles , Criança , China/epidemiologia , Preservativos/estatística & dados numéricos , Infecções por HIV/prevenção & controle , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Fatores de Risco , Doenças Virais Sexualmente Transmissíveis/prevenção & controle , Fatores Socioeconômicos , Inquéritos e Questionários , Adulto Jovem
4.
PLoS One ; 4(10): e7561, 2009 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-19855843

RESUMO

The whole-genome duplication (WGD) may provide a basis for the emergence of the very characteristic life style of Saccharomyces cerevisiae-its fermentation-oriented physiology and its capacity of growing in anaerobiosis. Indeed, we found an over-representation of oxygen-responding genes in the ohnologs of S. cerevisiae. Many of these duplicated genes are present as aerobic/hypoxic(anaerobic) pairs and form a specialized system responding to changing oxygen availability. HYP2/ANB1 and COX5A/COX5B are such gene pairs, and their unique orthologs in the 'non-WGD' Kluyveromyces lactis genome behaved like the aerobic versions of S. cerevisiae. ROX1 encodes a major oxygen-responding regulator in S. cerevisiae. The synteny, structural features and molecular function of putative KlROX1 were shown to be different from that of ROX1. The transition from the K. lactis-type ROX1 to the S. cerevisiae-type ROX1 could link up with the development of anaerobes in the yeast evolution. Bioinformatics and stochastic analyses of the Rox1p-binding site (YYYATTGTTCTC) in the upstream sequences of the S. cerevisiae Rox1p-mediated genes and of the K. lactis orthologs also indicated that K. lactis lacks the specific gene system responding to oxygen limiting environment, which is present in the 'post-WGD' genome of S. cerevisiae. These data suggested that the oxygen-responding system was born for the specialized physiology of S. cerevisiae.


Assuntos
Regulação Fúngica da Expressão Gênica , Kluyveromyces/genética , Kluyveromyces/metabolismo , Oxigênio/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Biologia Computacional/métodos , Genoma Fúngico , Genômica , Modelos Biológicos , Dados de Sequência Molecular , Oxigênio/química , Homologia de Sequência de Aminoácidos , Processos Estocásticos
5.
FEMS Yeast Res ; 7(5): 657-64, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17425674

RESUMO

NAD holds a key position in metabolism and cellular regulatory events as a major redox carrier and a signalling molecule. NAD biosynthesis pathways have been reconstructed and compared in seven yeast species with completely sequenced genomes, including Saccharomyces cerevisiae, Kluyveromyces lactis, Candida glabrata, Debaryomyces hansenii, Candida albicans, Yarrowia lipolytica and Schizosaccharomyces pombe. Both amino acid and nucleotide sequence similarity analysis in silico indicated that de novo NAD biosynthesis might not exist in K. lactis, C. glabrata and Schiz. pombe, while other species have the kynurenine pathway. It also showed that the NAD salvage pathway via nicotinic acid and nicotinic acid mononucleotide is conserved in all of these yeasts. Deletion of KlNPT1 (the gene for nicotinate phosphoribosyl-transferase) is lethal, which demonstrates that this salvage pathway, utilizing exogenous nicotinic acid, is the unique route to synthesize NAD in K. lactis. The results suggested that the basis of the variation of niacin requirements in yeasts lies in their different combinations of NAD biosynthesis pathways. The de novo pathway is absent but the salvage pathway is conserved in niacin-negative yeasts, while both pathways coexist in niacin-positive yeasts.


Assuntos
Ascomicetos/crescimento & desenvolvimento , NAD/biossíntese , Niacina/metabolismo , Ascomicetos/classificação , Ascomicetos/metabolismo , Deleção de Genes , Genes Fúngicos , Genoma Fúngico , Pentosiltransferases/genética , Pentosiltransferases/metabolismo , Especificidade da Espécie
6.
J Biol Chem ; 280(2): 1465-73, 2005 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-15525647

RESUMO

Plant growth and development are sensitive to light. Light-responsive DNA-binding transcription factors have been functionally identified. However, how transcription initiation complex integrates light signals from enhancer-bound transcription factors remains unknown. In this work, we characterized mutations within the Arabidopsis HAF2 gene encoding TATA-binding protein-associated factor TAF1 (or TAF(II)250). The mutation of HAF2 induced decreases on chlorophyll accumulation, light-induced mRNA levels, and promoter activity. Genetic analysis indicated that HAF2 is involved in the pathways of both red/far-red and blue light signals. Double mutants between haf2-1 and hy5-1, a mutation of a light signaling positive DNA-binding transcription factor gene, had a synergistic effect on photomorphogenic traits and light-activated gene expression under different light wavelengths, suggesting that HAF2 is required for interaction with additional light-responsive DNA-binding transcription factors to fully respond to light induction. Chromatin immunoprecipitation assays showed that the mutation of HAF2 reduced acetylation of histone H3 in light-responsive promoters. In addition, transcriptome analysis showed that the mutation altered the expression of about 9% of genes in young leaves. These data indicate that TAF1 encoded by the Arabidopsis HAF2 gene functions as a coactivator capable of integrating light signals and acetylating histones to activate light-induced gene transcription.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Fatores de Transcrição/metabolismo , Acetilação , Alelos , Arabidopsis/metabolismo , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas de Transporte/genética , DNA Bacteriano/genética , Perfilação da Expressão Gênica , Teste de Complementação Genética , Histonas/metabolismo , Hipocótilo/genética , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/metabolismo , Complexos de Proteínas Captadores de Luz , Dados de Sequência Molecular , Mutagênese Insercional/genética , Fenótipo , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Regiões Promotoras Genéticas/genética , Fatores de Transcrição/genética
7.
FEBS Lett ; 562(1-3): 147-54, 2004 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-15044016

RESUMO

Trihelix DNA-binding factors (or GT factors) bind to GT elements found in the promoters of many plant genes. Although the binding specificity and the transcriptional activity of some members (e.g. GT-1 and GT-2) have been studied, the regulatory function of this family of transcription factors remains largely unknown. In this work, we have characterised a new GT factor, namely GT-3a, and a closely related member, GT-3b. We show that (1) they can form either homo- or heterodimers but do not interact with GT-1; (2) they are predominantly expressed in floral buds and roots; (3) GT-3a cannot bind to the binding sites of GT-1 or GT-2, but binds to the cab2 and rbcS-1A gene promoters via the 5'-GTTAC sequence, which has been previously shown to be the core of the Site 1 type of GT elements. These results suggest that GT-3a and GT-3b belong to a distinct subgroup of GT factors and that each subgroup of GT factors binds to a functionally distinct type of cis-acting GT elements.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Arabidopsis/citologia , Arabidopsis/genética , Proteínas de Arabidopsis/classificação , Proteínas de Arabidopsis/genética , Sequência de Bases , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica de Plantas , Dados de Sequência Molecular , Proteínas Nucleares/classificação , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Filogenia , Regiões Promotoras Genéticas , Alinhamento de Sequência , Fatores de Transcrição/classificação , Fatores de Transcrição/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...