RESUMO
Here we show the existence of a novel subgenomic 4.4-kb RNA in cells infected with the prototypic replication-competent Friend or Moloney murine leukemia viruses (MuLV). This RNA derives by splicing from an alternative donor site (SD') within the capsid-coding region to the canonical envelope splice acceptor site. The position and the sequence of SD' was highly conserved among mammalian type C and D oncoviruses. Point mutations used to inactivate SD' without changing the capsid-coding ability affected viral RNA splicing and reduced viral replication in infected cells.
Assuntos
Processamento Alternativo , Vírus da Leucemia Murina de Friend/genética , Vírus da Leucemia Murina de Moloney/genética , RNA Viral/genética , Animais , Capsídeo/genética , Células Cultivadas , Vírus da Leucemia Murina de Friend/metabolismo , Vírus da Leucemia Murina de Friend/fisiologia , Camundongos , Vírus da Leucemia Murina de Moloney/metabolismo , Vírus da Leucemia Murina de Moloney/fisiologia , Mutação , RNA Viral/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica , Replicação ViralRESUMO
We have investigated at a molecular level the requirements for germinal vesicle (nuclear) material during the course of meiosis in Xenopus oocytes. We present the localization of some cell cycle proteins in stage VI oocytes; most of those analyzed are cytoplasmic, although some (MAD, 26S proteasome) are distributed between the cytoplasm and the germinal vesicle. By analyzing changes in individual oocytes, we find that the unphosphorylated form of cyclin B2 disappears and the phosphorylated form is then degraded in both nucleated and enucleated oocytes. Enucleated oocytes are also capable of resynthesizing both cyclin B1 and cyclin B2 after the initial degradation and of reactivating cdc2 kinase. Synthesis of mos protein and activation of MAP kinase concomitant with cdc2-cyclin B reactivation are also unaffected by prior removal of the germinal vesicle.