RESUMO
sn-Glycerol-3-phosphate dehydrogenase (glycerol-P dehydrogenase, EC 1.1.1.8) activity levels in seven tissues of adult mice vary approximately 100-fold from a low of 0.1 unit/mg of protein in the cerebral cortex to a high of 8 units/mg of protein in the brown fat of cold-adapted mice; the brown fat accounts for approximately 1% of the total tissue protein. This high degree of variation in the quantitative expression of an enzyme in different tissues has provided us with a system for analyzing the mechanism by which tissue specific variation for a given gene product is controlled. To this end we have measured the amount of immunoreactive enzyme and the level of translatable glycerol-P dehydrogenase mRNA and have localized the glycerol-P dehydrogenase-positive cells by immunocytochemistry. We have found that the amount of enzyme protein in a tissue is strongly correlated with the level of its translatable mRNA (correlation coefficient = 0.996) and that in several cases the differences among tissues can be explained by differences in the numbers of glycerol-P dehydrogenase-positive cells.
Assuntos
Glicerolfosfato Desidrogenase/biossíntese , Biossíntese de Proteínas , RNA Mensageiro/metabolismo , Tecido Adiposo Marrom/enzimologia , Animais , Cerebelo/enzimologia , Córtex Cerebral/enzimologia , Temperatura Baixa , Histocitoquímica , Técnicas Imunoenzimáticas , Rim/enzimologia , Fígado/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos , Especificidade de Órgãos , Testículo/enzimologiaAssuntos
Encéfalo/enzimologia , Glicerolfosfato Desidrogenase/biossíntese , RNA Mensageiro/genética , Animais , Encéfalo/crescimento & desenvolvimento , Sistema Livre de Células , Feminino , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Poli A/metabolismo , Biossíntese de Proteínas , Análogos de Capuz de RNA/farmacologia , RNA Mensageiro/metabolismo , Coelhos , Reticulócitos/metabolismo , Especificidade da EspécieRESUMO
Moloney murine leukemia virus was harvested automatically within 60 min of release from chronically infected NIH/3T3 cells (clone 1) cultured on bundles of synthetic capillaries. Production of virus as measured by a determination of reverse transcriptase activity and by the XC syncytia assay demonstrated that highly infectious "rapid-harvest" virus was recovered from NIH/3T3 cells (clone 1) grown for periods of up to 10 days.
Assuntos
Vírus da Leucemia Murina de Moloney/crescimento & desenvolvimento , Cultura de Vírus/instrumentação , Linhagem Celular , Células Clonais , Técnicas Citológicas , Vírus da Leucemia Murina de Moloney/patogenicidade , DNA Polimerase Dirigida por RNA/metabolismoRESUMO
Merodiploid complementation analysis of the constitutive synthesis of the D-ribokinase and the D-ribose permease in Escherichia coli B/r has shown that the constitutive D-ribose operon is genetically controlled by a transdominant regulatory gene closely linked to the D-ribokinase and D-ribose permease structural genes. The regulatory mechanism for this operon shows no requirement for operator-repressor interaction, rather a truly positive control mechanism and thus suggests an extension of the operon model in its application to constitutive enzyme regulation in bacteria.