RESUMO
Infection of Vero cells with Tacaribe virus stocks containing a high ratio of standard (plaque-forming) viruses to defective interfering particles (DIP) induced inhibition of the host cell Ca2+ ATPase (Ca2+ pump) and the ouabain-sensitive Na+/K+ ATPase (Na+/K+ pump). The Mg2+ ATPase which is not involved in cation transport was not affected. The presence of DIP in the inocula protected the cells from alteration of the transport-associated ATPases induced by standard viruses.
Assuntos
Arenaviridae/fisiologia , ATPases Transportadoras de Cálcio/antagonistas & inibidores , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , Animais , Vírus Defeituosos/fisiologia , Células Vero , Replicação ViralRESUMO
When mice fed on a protein-depleted diet are restored to the normal diet (re-feeding), there is a 2-fold increase in liver RNA polymerase I activity. The results obtained with pactamycin; an inhibitor of protein synthesis, suggest the presence of short-lived proteins which are required for inducing an activated state of transcription. To gain an insight on whether ornithine decarboxylase (ODC)--the first enzyme in polyamine biosynthesis--is the labile protein that regulates rRNA synthesis, we have investigated the correlation between liver ODC and RNA polymerase I activities under different nutritional conditions. We have also studied the effects of alpha-difluormethylornithine (alpha-DFMO)--a specific ODC inactivator--on rRNA transcription. The results indicate that, after re-feeding, there is an abrupt increase in ODC activity that rapidly declines, while RNA polymerase I is still increasing. On the other hand, alpha-DFMO--which inhibits the elevated activity of ODC--has not effect on rRNA transcription.
Assuntos
Dieta , Fígado/enzimologia , Ornitina Descarboxilase/metabolismo , RNA Polimerase I/metabolismo , Animais , Eflornitina , Masculino , Camundongos , Camundongos Endogâmicos , Ornitina/análogos & derivados , Ornitina/metabolismo , Inibidores da Ornitina Descarboxilase , Deficiência de Proteína/metabolismoRESUMO
When mice fed on a protein-depleted diet are restored to the normal diet (re-feeding), there is a 2-fold increase in liver RNA polymerase I activity. The results obtained with pactamycin; an inhibitor of protein synthesis, suggest the presence of short-lived proteins which are required for inducing an activated state of transcription. To gain an insight on whether ornithine decarboxylase (ODC)--the first enzyme in polyamine biosynthesis--is the labile protein that regulates rRNA synthesis, we have investigated the correlation between liver ODC and RNA polymerase I activities under different nutritional conditions. We have also studied the effects of alpha-difluormethylornithine (alpha-DFMO)--a specific ODC inactivator--on rRNA transcription. The results indicate that, after re-feeding, there is an abrupt increase in ODC activity that rapidly declines, while RNA polymerase I is still increasing. On the other hand, alpha-DFMO--which inhibits the elevated activity of ODC--has not effect on rRNA transcription.