RESUMEN
The effect of field drought on gene expression in developing Zea mays L. grain and the influence of the imbalance of essential amino acids on the expression of genes in white-rat liver at the mRNA stability level were studied. A special ommp system, which included incubation (65 degrees C, 5 min) of an aqueous preparation of highly purified, high molecular-weight RNA isolated in the presence of Mg2+, was used for the analysis of mRNAs relative stability in eukaryotes. Drought changed the relative stability of seven specific mRNA in the maize developing grain: there occurred a considerable stabilization of the eEF-1 alpha mRNA and, conversely, a destabilization of the 19-kDa zein mRNA. The imbalance for lysine and tryptophan reduced the stability of the total polyadenylated mRNA and the eEF-1 alpha mRNA of rat liver. The mRNA stability positively correlated with animal growth. Thus, using the ommp system, the effect of stressful factors on the stability of specific mRNA in eukaryotes--depending on mRNA species, stressful factors, and the tissue--was shown.
Asunto(s)
Procesamiento Postranscripcional del ARN , ARN Mensajero/genética , Estrés Fisiológico/genética , Triticum/genética , Zea mays/genética , Animales , Lisina/metabolismo , Modelos Genéticos , Ratas , Triptófano/metabolismoRESUMEN
The lifetime of the zein mRNA in a developing corn (Zea mays L.) kernel under genome transcription blockade with actinomycin D (in vivo) and in a cell-free system (in vitro) was studied. After a 10 h blockade of gene transcription with actinomycin D, only 55% of 19 kDa zein mRNA and 40% of 22 kDa mRNA were detected in a developing kernel of normal corn. In that of the opaque-2 mutant 80% of 19 kDa zein mRNA remained. To examine the relative stability of poly(A)-containing mRNA, cell-free systems from rabbit reticulocyte lysate and wheat-germ extract were used. In both cases only 40% of 19 kDa zein mRNA and 60% of 22 kDa zein mRNA decayed during a 30 min incubation. Differential mRNA degradation of poly(A)-containing zein mRNA was observed on affinity chromatography; poly(A)-containing 19 kDa zein mRNA from normal corn partially decayed by elution from poly(U)-Sepharose whereas that from opaque-2 remained stable. These data suggest that differential mRNA stability is an important factor in the regulation of the zein gene expression in a developing corn kernel.
Asunto(s)
ARN Mensajero/metabolismo , Zea mays/metabolismo , Zeína/biosíntesis , Animales , Secuencia de Bases , Sistema Libre de Células , Sondas de ADN , Dactinomicina/farmacología , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Cinética , Datos de Secuencia Molecular , Peso Molecular , Biosíntesis de Proteínas , Conejos , Reticulocitos/metabolismo , Semillas , Transcripción Genética/efectos de los fármacos , Triticum/metabolismo , Zea mays/crecimiento & desarrolloRESUMEN
The DNA-DNA hybridization method was used to study 4 species of bacteria of the genus Listeria. Concerning the DNA homology, L. monocytogenes strains may be divided into several species (in particular, the pathogenic forms may be isolated into independent taxon), in correlation with their biochemical and serological properties. Most of the studied strains of this species exhibit a high level of DNA homology--65-100%. Bacteria of the L. grayi and L. murrayi species are closely related to each other (90% of DNA homology), the reasonable suggestion being to unite them into a single species. L. denitrificans has 7% of DNA homology with the DNA of the other three species suggesting that it should be excluded from the genus Listeria.