RESUMO
Repeated episodes of 1-h restraint stress were accompanied by a decrease in the sensitivity of blood leukocytes and cytochrome P450-dependent monooxygenases of the liver to recombinant IL-1ß. These changes are associated with the anti-inflammatory hepatoprotective effect of chronic stress.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Interleucina-1beta/farmacologia , Leucócitos/metabolismo , Fígado/metabolismo , Animais , Feminino , Interleucina-1beta/administração & dosagem , Leucócitos/efeitos dos fármacos , Masculino , Ratos , Restrição Física , Estresse Fisiológico , Estresse PsicológicoRESUMO
Trans-translation, the unique process of the synthesis of the single polipeptide chain from both mRNA and the coding part of tmRNA, is necessary for the cell viability in the changeable environment. The new data concerning the main participants and physiological role of trans-translation and the conditions in which it occurs are summarized. The possible tmRNA function in the translation quality control is also discussed.
Assuntos
Biossíntese de Proteínas/fisiologia , RNA Bacteriano/fisiologia , RNA Mensageiro/fisiologia , Fenômenos Fisiológicos Celulares , Conformação de Ácido Nucleico , Biossíntese de Proteínas/genética , RNA Bacteriano/genética , RNA Bacteriano/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribossomos/fisiologiaRESUMO
Transfer-messenger RNA (tmRNA) is a stable RNA in bacteria of 360 +/- 40 nucleotides that can be charged with alanine and can function as both tRNA and mRNA. Ribosomes that are stalled either in a coding region of mRNA or at the 3' end of an mRNA fragment lacking a stop codon are rescued by replacing their mRNA for tmRNA. Here we demonstrate that the interaction of tmRNA with the elongation factor Tu shows unexpected features. Deacylated tmRNA can form a complex with either EF-Tu.GDP or EF-Tu.GTP, the association constants are about one order of magnitude smaller than that of an Ala-tRNA.EF-Tu.GTP complex. tmRNA as well as Ala-tmRNA can be efficiently cross-linked with EF-Tu.GDP using a zero-length cross-link. The efficiency of cross-linking in the case of deacylated tmRNA does not depend on an intact CCA-3' end and is about the same, regardless whether protein mixtures such as the post-ribosomal supernatant (S100 enzymes) or purified EF-Tu are present. Two cross-linking sites with EF-Tu.GDP have been identified that are located outside the tRNA part of tmRNA, indicating an unusual interaction of tmRNA with EF-Tu.GDP.
Assuntos
Fator Tu de Elongação de Peptídeos/metabolismo , RNA Mensageiro/metabolismo , Sistema Livre de Células , Códon de Terminação , Reagentes de Ligações Cruzadas/farmacologia , Escherichia coli/metabolismo , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Cinética , Modelos Biológicos , Fator Tu de Elongação de Peptídeos/genética , Plasmídeos/metabolismo , Ligação Proteica , Estrutura Secundária de Proteína , RNA/metabolismo , RNA de Transferência/metabolismo , Aminoacil-RNA de Transferência/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Tripsina/farmacologiaRESUMO
DNA synthesis was studied during germination by following the rate of incorporation of radioactive thymidine into high molecular weight DNA. A peak of DNA synthesis was observed between the 8th and the 12th hour, i.e. before the beginning of the semi-conservative replication of genomic DNA, accompanied by an increase in the DNA content of the embryo. By the use of nucleoid sedimentation and nick-translation it was shown that, during the first hours of germination, extensive repair occurs of the DNA single-strand breaks present in the dry embryo. As a result, the DNA of the 16-h-germinated embryo acquires the conformation typical of that of the root meristemic cells active in transcription and replication.In addition we have shown that cytoplasmic organelle (most probably mitochondrial) DNA synthesis is very active during the prereplicative state which confirms earlier microscopic data on mitochondrial biogenesis during early germination.
