RESUMO
A cDNA derived from an abundant maize pith mRNA transcript and its corresponding genomic equivalent have been isolated and characterized. High transcript levels are seen in the pith and young leaves of maize plants, while no transcript is detected in seed tissue of any age. The protein encoded by the isolated gene has considerable homology with tryptophan synthase alpha subunit (trpA) from other organisms and the cDNA clone can complement an E. coli trpA mutant. These data support the conclusion that this cDNA and the corresponding genomic clone encode a maize trpA protein.
Assuntos
Triptofano Sintase/genética , Zea mays/genética , Sequência de Aminoácidos , Northern Blotting , DNA Complementar , Escherichia coli/genética , Expressão Gênica , Genes de Plantas , Teste de Complementação Genética , Dados de Sequência Molecular , Mutação , RNA Mensageiro/genética , Homologia de Sequência de Aminoácidos , Zea mays/enzimologiaRESUMO
A rapid analysis of Bacillus thuringiensis strains predictive of insecticidal activity was established by using polymerase chain reaction (PCR) technology. Primers specific to regions of high homology within genes encoding three major classes of B. thuringiensis crystal proteins were used to generate a PCR product profile characteristic of each insecticidal class. Predictions of insecticidal activity were made on the basis of the electrophoretic patterns of the PCR products. Included in the screen were PCR primers specific for cryI, cryIII, and cryIV genes, which are insecticidal for lepidopterans, coleopterans, and dipterans, respectively. Known B. thuringiensis strains as well as unidentified strains isolated from soil and insect cadavers were analyzed by PCR. Small amounts of crude sample lysates were assayed in a single PCR reaction containing 12 to 20 primers capable of distinguishing between the different insecticidal genes. Insecticidal activity predicted by the PCR screen was found to correspond with the insecticidal activity of insect bioassays. In addition to identifying strains with known insecticidal genes, the PCR screen can identify strains with altered electrophoretic patterns containing potentially novel genes.
Assuntos
Bacillus thuringiensis/química , Proteínas de Bactérias/farmacologia , Toxinas Bacterianas , Endotoxinas , Inseticidas/farmacologia , Reação em Cadeia da Polimerase , Animais , Bacillus thuringiensis/isolamento & purificação , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Sequência de Bases , Besouros/efeitos dos fármacos , DNA Bacteriano/química , Dípteros/efeitos dos fármacos , Genes Bacterianos , Proteínas Hemolisinas , Inseticidas/química , Lepidópteros/efeitos dos fármacos , Dados de Sequência Molecular , Controle Biológico de VetoresRESUMO
The detergent-resistance properties of 208 independent isolates of the Enterobacteriaceae have been examined. Of these bacterial strains, 200 were able to grow in the presence of greater than or equal to 5% sodium dodecyl sulfate, including all members of the Klebsielleae tribe. This resistance does not appear to be plasmid encoded. It is proposed that detergent-resistant organisms be termed saponotolerant or saponophilic, by analogy with other microorganisms occupying harsh ecological niches. In contrast to their prevalent resistance to anionic detergents, not one of the 208 strains tested was found to grow in the presence of three different cationic detergents. This sensitivity to cationic detergents may be of significance in combating nosocomial infections.
Assuntos
Detergentes/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Dodecilsulfato de Sódio/farmacologia , Tensoativos/farmacologia , Resistência Microbiana a Medicamentos , Enterobacteriaceae/genética , PlasmídeosRESUMO
Growth of Enterobacter cloacae in a glucose asparagine salts medium in the presence of 10% sodium dodecyl sulfate entailed an energy burden in the form of a 20% decreased cell yield, a 30% faster rate of glucose utilization, and a 70% increased rate of oxygen consumption. Similar detergent-induced decreases in cell yield were observed with 10 other sugars and sugar alcohols. Only glycerol supported equivalent cell growth in the presence and absence of sodium dodecyl sulfate. A model is presented which interprets these observations in terms of an altered membrane potential which makes active transport energetically less efficient.
Assuntos
Metabolismo Energético/efeitos dos fármacos , Enterobacter/efeitos dos fármacos , Enterobacteriaceae/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Dodecilsulfato de Sódio/farmacologia , Transporte Biológico Ativo/efeitos dos fármacos , Detergentes/farmacologia , Resistência Microbiana a Medicamentos , Enterobacter/crescimento & desenvolvimento , Enterobacter/metabolismo , Glucose/metabolismo , Potenciais da Membrana/efeitos dos fármacosRESUMO
The growth of Enterobacter cloacae in 25% sodium dodecyl sulfate is described. The bacteria appeared to tolerate sodium dodecyl sulfate rather than metabolize it. The process was energy dependent, and cell lysis occurred during stationary phase. Extreme detergent resistance may be characteristic of the genus Enterobacter.