摘要:

AbstractSpontaneous reversion rates of biochemical mutants in cells ofSaccharomyces cerevisiaeundergoing meiosis are several times higher than those of cells mitotically reproducing. It has been demonstrated that the great majority of revertants occurring during a meiotic process are associated with chromosomal exchanges in the region of the specific locus. This leads to the hypothesis that during meiosis back mutations occur as a consequence of unequal crossing‐over causing base losses or insertions in the DNA and, therefore, restroration of a sequence compatible with the synthesis of functioning proteins. The same phenomenon holds true also for forward mutations. Preliminary experiments show that, as expected, mutations due to base substitutions do not revert in meiosis at a rate higher than in mitosis. Exchange‐associated mutations seem to occur also in other organisms such as bacteriophages, bacteria,Neurospora, andDrosoph

ISSN:0095-9898    

DOI:10.1002/jcp.1030640413

出版商:The Wistar Institute of Anatomy and Biology    

年代:1964

数据来源: WILEY

摘要:

AbstractThe Rous sarcoma virus (RSV) is unique among tumor viruses in the great speed and high frequency with which it induces the malignant transformation in the infected cell. It is also unique in its defectiveness — it cannot reproduce new, infectious virus particles unless a helper virus is present. Such a helper virus, known as RAV, occurs in stocks of the Bryan high titer strain of RSV. It is a member of the avian leukosis group of viruses. All the other avian leukosis viruses tested to date can substitute for RAV as helper viruses. An analysis has been carried out of the independent and helper‐dependent functions of RSV. RSV carries out the malignant transformation of cells without the aid of helper virus and controls the morphology of the transformation. It also reproduces its own genetic material in solitary infection. However, it is completely dependent on helper virus for synthesis of its protein coat. As a result, RSV bears the antigenic identity of its helper virus. By using different helper viruses, it has been found that the ability of RSV to infect chicken cells of a given genetic constitution depends on the coat of the virus. In addition, the susceptibility of RSV to interference by leukosis viruses depends on similarity between the coat of the leukosis virus and that of the super‐infecting RSV. The results to date indicate both these forms of cellular resistance to RSV are associated with the failure of RSV to penetrate the

ISSN:0095-9898    

DOI:10.1002/jcp.1030640414

出版商:The Wistar Institute of Anatomy and Biology    

年代:1964

数据来源: WILEY

ISSN:0095-9898    

DOI:10.1002/jcp.1030640415

出版商:The Wistar Institute of Anatomy and Biology    

年代:1964

数据来源: WILEY

ISSN:0095-9898    

DOI:10.1002/jcp.1030640402

出版商:The Wistar Institute of Anatomy and Biology    

年代:1964

数据来源: WILEY