RESUMO
A barley gene encoding a novel DNA-binding protein (HRT) was identified by southwestern screening with baits containing a gibberellin phytohormone response element from an alpha-amylase promoter. The HRT gene contains two introns, the larger of which (5722 base pairs (bp)) contains a 3094-bp LINE-like element with homology to maize Colonist1. In vitro mutagenesis and zinc- and DNA-binding assays demonstrate that HRT contains three unusual zinc fingers with a CX8-9CX10CX2H consensus sequence. HRT is targeted to nuclei, and homologues are expressed in other plants. In vivo, functional tests in plant cells indicate that full-length HRT can repress expression from certain promoters including the Amy1/6-4 and Amy2/32 alpha-amylase promoters. In contrast, truncated forms of HRT containing DNA-binding domains can activate, or derepress, transcription from these promoters. Northern hybridizations indicate that HRT mRNA accumulates to low levels in various tissues. Roles for HRT in mediating developmental and phytohormone-responsive gene expression are discussed.
Assuntos
Proteínas de Ligação a DNA/genética , Hordeum/genética , Proteínas Repressoras/genética , Dedos de Zinco/genética , Álcool Desidrogenase/genética , Sequência de Aminoácidos , Compartimento Celular , DNA Complementar/genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Dados de Sequência Molecular , Sinais de Localização Nuclear , Fragmentos de Peptídeos/genética , Proteínas de Plantas/genética , Sequências Reguladoras de Ácido Nucleico , Homologia de Sequência de Aminoácidos , Distribuição Tecidual , alfa-Amilases/genéticaRESUMO
Primary rubella infections during the first trimester of pregnancy are an indication for the termination, although not all of fetuses will be infected. Concerning this situation a prenatal rubella diagnostic in 55 pregnant women was carried out to demonstrate a fetal infection. Simultaneously or separately, as methods the determination of rubella IgM antibodies in fetal blood, the demonstration of viral RNA by DNA-RNA-hybridization and the cultivation of rubella virus from amniotic fluid samples were used. In 7 of 40 women the investigation of amniotic fluids showed a positive reaction of the hybridization, in 2 cases a rubella virus could be isolated. IgM rubella antibodies were found in 5 fetuses. Because of its insufficient effectivity at present the prenatal rubella diagnostic should be applied only in special situations, e.g. in cases of a wanted child.
