962 resultados para Fow and BS
(Table 5.1.10) Methane formation and consumption in the upper meter sediment layer of the Bering Sea
Resumo:
We examined the mechanisms by which two different types of photonic radiation, short wavelength UV (UV-C) and γ radiation, activate transcription factor NF-κB. Exposure of mammalian cells to either form of radiation resulted in induction with similar kinetics of NF-κB DNA binding activity, nuclear translocation of its p65(RelA) subunit, and degradation of the major NF-κB inhibitor IκBα. In both cases, induction of NF-κB activity was attenuated by proteasome inhibitors and a mutation in ubiquitin-activating enzyme, suggesting that both UV-C and γ radiation induce degradation of IκBs by means of the ubiquitin/proteasome pathway. However, although the induction of IκBα degradation by γ rays was dependent on its phosphorylation at Ser-32 and Ser-36, UV-C-induced IκBα degradation was not dependent on phosphorylation of these residues. Even the “super repressor” IκBα mutant, which contains alanines at positions 32 and 36, was still susceptible to UV-C-induced degradation. Correspondingly, we found that γ radiation led to activation of IKK, the protein kinase that phosphorylates IκBα at Ser-32 and Ser-36, whereas UV-C radiation did not. Furthermore, expression of a catalytically inactive IKKβ mutant prevented NF-κB activation by γ radiation, but not by UV-C. These results indicate that γ radiation and UV-C activate NF-κB through two distinct mechanisms.
Resumo:
Bloom syndrome (BS) is a rare cancer-predisposing disorder in which the cells of affected persons have a high frequency of somatic mutation and genomic instability. BLM, the protein altered in BS, is a RecQ DNA helicase. This report shows that BLM is found in the nucleus of normal human cells in the nuclear domain 10 or promyelocytic leukemia nuclear bodies. These structures are punctate depots of proteins disrupted upon viral infection and in certain human malignancies. BLM is found primarily in nuclear domain 10 except during S phase when it colocalizes with the Werner syndrome gene product, WRN, in the nucleolus. BLM colocalizes with a select subset of telomeres in normal cells and with large telomeric clusters seen in simian virus 40-transformed normal fibroblasts. During S phase, BS cells expel micronuclei containing sites of DNA synthesis. BLM is likely to be part of a DNA surveillance mechanism operating during S phase.
Resumo:
Three different base paired stems form between U2 and U6 snRNA over the course of the mRNA splicing reaction (helices I, II and III). One possible function of U2/U6 helix II is to facilitate subsequent U2/U6 helix I and III interactions, which participate directly in catalysis. Using an in vitro trans-splicing assay, we investigated the function of sequences located just upstream from the branch site (BS). We find that these upstream sequences are essential for stable binding of U2 to the branch region, and for U2/U6 helix II formation, but not for initial U2/BS pairing. We also show that non-functional upstream sequences cause U2 snRNA stem–loop IIa to be exposed to dimethylsulfate modification, perhaps reflecting a U2 snRNA conformational change and/or loss of SF3b proteins. Our data suggest that initial binding of U2 snRNP to the BS region must be stabilized by an interaction with upstream sequences before U2/U6 helix II can form or U2 stem–loop IIa can participate in spliceosome assembly.
Resumo:
Most studies employing experimental models of unilateral glaucoma have used the normotensive contralateral eye as the normal control. However, some studies have recently reported the activation of the retinal macroglia and microglia in the uninjured eye, suggesting that the eye contralateral to experimental glaucoma should not be used as a control. This review analyzes the studies describing the contralateral findings and discusses some of the routes through which the signals can reach the contralateral eye to initiate the glial reactivation.
Resumo:
The argument of this paper is that several empirical puzzles in the citizenship literature are rooted in the failure to distinguish between the mainly legal concept of nationality and the broader, political concept of citizenship. Using this distinction, the paper analysis the evolution of German and American nationality laws over the last 200 years. The historical development of both legal structures shows strong communalities. With the emergence of the modern system of nation states, the attribution of nationality to newborn children is ascribed either via the principle of descent or place of birth. With regard to the naturalization of adults, there is an increasing ethnization of law, which means that the increasing complexities of naturalization criteria are more and more structured along ethnic ideas. Although every nation building process shows some elements of ethnic self-description, it is difficult to use the legal principles of ius sanguinis and ius soli as indicators of ethnic or non-ethnic modes of community building.
Resumo:
Research on ecosystem services has become a dominant field within environmental management, framing the way in which human–nature relationships are understood and managed. Although ecosystem services are usually defined as ‘the benefits that humans receive from nature’, our work shows that most services are actually co-produced by a mixture of natural capital and various forms of social, human, financial and technological capital. Here, we review how ecosystem services are co-produced, and then we assess how this affects the quantity, quality, trade-offs, resilience and the equity of the distribution of ecosystem services. Then we discuss the implications of co-production for sustainability. Finally, we present some challenges for an adequate consideration of co-production within the assessment of ecosystem services.
Resumo:
Includes bibliography references.