منابع مشابه
Sigma and RNA polymerase: an on-again, off-again relationship?
In bacteria, a fundamental level of gene regulation occurs by competitive association of promoter-specificity factors called sigmas with RNA polymerase (RNAP). This sigma cycle paradigm underpins much of our understanding of all transcriptional regulation. Here, we review recent challenges to the sigma cycle paradigm in the context of its essential features and of the structural basis of sigma ...
متن کاملTelomere stability and carcinogenesis: an off-again, on-again relationship.
Previous studies in mice have demonstrated antagonistic effects of telomerase loss on carcinogenesis. Telomere attrition can promote genome instability, thereby stimulating initiation of early-stage cancers, but can also inhibit tumorigenesis by promoting permanent cell growth arrest or death. Human cancers likely develop in cell lineages with low levels of telomerase, leading to telomere losse...
متن کاملT helper cell differentiation: on again, off again.
Recent studies raise the possibility that T helper (Th) polarization may be attributable to generalized activation and regulated silencing rather than regulated activation of target cytokine genes. The binding of transcription factors GATA-3 or T-bet to specific enhancers does recruit transcription factors such as NFAT-1 to IL-4 or IFNgamma promoters, respectively; however, GATA-3 also intrinsi...
متن کاملAgain on Axis-Traction Forceps
Since these Tarnier forceps were discussed among us they have been discussed in many associations, and by many writers, and the voices are still so discordant that it seems as if a final judgment as to their value were still far off. I am anxious to bring them up again in the Society, that we may have an opportunity of considering some of the objections that have been advanced to their use, and...
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ژورنال
عنوان ژورنال: Conservation Biology
سال: 1993
ISSN: 0888-8892,1523-1739
DOI: 10.1046/j.1523-1739.1993.07030734-2.x