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941.
942.
943.
944.
Bonalume Neto R 《Nature》1999,402(6760):344-345
945.
Bacterial suicide through stress 总被引:9,自引:0,他引:9
Outside of the laboratory, bacterial cells are constantly exposed to stressful conditions, and an ability to resist those
stresses is essential to their survival. However, the degree of stress required to bring about cell death varies with growth
phase, amongst other parameters. Exponential phase cells are significantly more sensitive to stress than stationary phase
ones, and a novel hypothesis has recently been advanced to explain this difference in sensitivity, the suicide response. Essentially,
the suicide response predicts that rapidly growing and respiring bacterial cells will suffer growth arrest when subjected
to relatively mild stresses, but their metabolism will continue: a burst of free-radical production results from this uncoupling
of growth from metabolism, and it is this free-radical burst that is lethal to the cells, rather than the stress per se. The
suicide response hypothesis unifies a variety of previously unrelated empirical observations, for instance induction of superoxide
dismutase by heat shock, alkyl-hydroperoxide reductase by osmotic shock and catalase by ethanol shock. The suicide response
also has major implications for current [food] processing methods.
Received 29 March 1999; received after revision 14 May 1999; accepted 17 May 1999 相似文献
946.
At the end of mitosis, daughter cells are separated from each other by cytokinesis. This process involves equal partitioning
and segregation of cytoplasm between the two cells. Despite years of study, the mechanism driving cytokinesis in animal cells
is not fully understood. Actin and myosin are major components of the contractile ring, the structure at the equator between
the dividing cells that provides the force necessary to constrict the cytoplasm. Despite this, there are also tantalizing
results suggesting that cytokinesis can occur in the absence of myosin. It is unclear what the roles are of the few other
contractile ring components identified to date. While it has been difficult to identify important proteins involved in cytokinesis,
it has been even more challenging to pinpoint the regulatory mechanisms that govern this vital process. Cytokinesis must be
precisely controlled both spatially and temporally; potential regulators of these parameters are just beginning to be identified.
This review discusses the recent progress in our understanding of cytokinesis in animal cells and the mechanisms that may
regulate it.
Received 24 August 1998; received after revision 9 October 1998; accepted 9 October 1998 相似文献
947.
Immune responses to DNA vaccines 总被引:16,自引:0,他引:16
DNA vaccines, based on plasmid vectors expressing an antigen under the control of a strong promoter, have been shown to induce
protective immune responses to a number of pathogens, including viruses, bacteria and parasites. They have also displayed
efficacy in treatment or prevention of cancer, allergic diseases and autoimmunity. Immunologically, DNA vaccines induce a
full spectrum of immune responses that include cytolytic T cells, T helper cells and antibodies. The immune response to DNA
vaccines can be enhanced by genetic engineering of the antigen to facilitate its presentation to B and T cells. Furthermore,
the immune response can be modulated by genetic adjuvants in the form of vectors expressing biologically active determinants
or by more traditional adjuvants that facilitate uptake of DNA into cells. The ease of genetic manipulation of DNA vaccines
invites their use not only as vaccines but also as research tools for immunologists and microbiologists.
Received 26 October 1998; received after revision 3 December 1998; accepted 3 December 1998 相似文献
948.
Amin AR Attur MG Pillinger M Abramson SB 《Cellular and molecular life sciences : CMLS》1999,56(3-4):305-312
Recent studies have suggested that aspirin and aspirin-like compounds have a variety of actions in addition to their well-studied
ability to inhibit cyclooxygenases. These actions include inhibition of the uncoupling of oxidative phosphorylation, decreases
in adenosine triphosphate stores, increases in extracellular adenosine, downregulation of the expression and activity of inducible
nitric oxide synthetase, inhibition and/or stimulation of various mitogen-activated protein kinase activities and inhibition
of nuclear factor binding κB site (NF-κB) activation. Moreover, aspirin-like compounds have recently been shown to have previously
unappreciated clinical and biological effects, some apparently independent of cyclooxygenase. In this review we discuss the
various mechanisms of action of aspirin-like compounds and their relevance to clinical disease and therapy.
Received 1 February 1999; received after revision 1 April 1999; accepted 7 May 1999 相似文献
949.
Favatier F Jacquier-Sarlin MR Swierczewski E Polla BS 《Cellular and molecular life sciences : CMLS》1999,56(7-8):701-708
A bi-allelic polymorphism found in the regulatory region of the human heat shock (HS) protein (HSP) hsp70-1 gene, which comprises an A-->C transversion, 3 bp upstream of the HS element (HSE), has been associated with extended HLA haplotypes. In view of the chaperoning and protective functions of Hsp70, we investigated whether this hsp70-1 bi-allelic polymorphism could modulate the stress response, which may relate to enhanced resistance or susceptibility to certain diseases. We compared the basal and HS-induced HS factor (HSF)-binding activity of the two polymorphic HSEs, hsp70-1 mRNA accumulation and HSP expression in two human Epstein Barr virus (EBV)-transformed B cell lines typed for hsp70-1 promoter alleles. Our results suggest that hsp70-1 promoter polymorphism does not influence HSF-binding activity, hsp70 mRNA accumulation or synthesis in human EBV-transformed B cell lines. 相似文献
950.
MAP kinases in plant signal transduction 总被引:10,自引:0,他引:10
Mitogen-activated protein kinase (MAPK) pathways are modules involved in the transduction of extracellular signals to intracellular
targets in all eukaryotes. Distinct MAPK pathways are regulated by different extracellular stimuli and are implicated in a
wide variety of biological processes. In plants there is evidence for MAPKs playing a role in the signaling of abiotic stresses,
pathogens and plant hormones. The large number and divergence of plant MAPKs indicates that this ancient mechanism of bioinformatics
is extensively used in plants and may provide a new molecular handle on old questions. 相似文献