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981.
Hoose SA Rawlings JA Kelly MM Leitch MC Ababneh QO Robles JP Taylor D Hoover EM Hailu B McEnery KA Downing SS Kaushal D Chen Y Rife A Brahmbhatt KA Smith R Polymenis M 《PLoS genetics》2012,8(3):e1002590
Upstream events that trigger initiation of cell division, at a point called START in yeast, determine the overall rates of cell proliferation. The identity and complete sequence of those events remain unknown. Previous studies relied mainly on cell size changes to identify systematically genes required for the timely completion of START. Here, we evaluated panels of non-essential single gene deletion strains for altered DNA content by flow cytometry. This analysis revealed that most gene deletions that altered cell cycle progression did not change cell size. Our results highlight a strong requirement for ribosomal biogenesis and protein synthesis for initiation of cell division. We also identified numerous factors that have not been previously implicated in cell cycle control mechanisms. We found that CBS, which catalyzes the synthesis of cystathionine from serine and homocysteine, advances START in two ways: by promoting cell growth, which requires CBS's catalytic activity, and by a separate function, which does not require CBS's catalytic activity. CBS defects cause disease in humans, and in animals CBS has vital, non-catalytic, unknown roles. Hence, our results may be relevant for human biology. Taken together, these findings significantly expand the range of factors required for the timely initiation of cell division. The systematic identification of non-essential regulators of cell division we describe will be a valuable resource for analysis of cell cycle progression in yeast and other organisms. 相似文献
982.
NAC proteins: regulation and role in stress tolerance 总被引:6,自引:0,他引:6
983.
984.
Sickle cell hemoglobin conveys resistance to malaria. In this issue of Cell Host & Microbe, LaMonte et?al. (2012) demonstrate a surprising mechanism for this innate immunity. A microRNA enriched in sickle red blood cells is translocated into the parasite, incorporated covalently into P.?falciparum mRNAs and inhibits parasite growth. 相似文献
985.
Dutta NK Mehra S Martinez AN Alvarez X Renner NA Morici LA Pahar B Maclean AG Lackner AA Kaushal D 《PloS one》2012,7(1):e28958
The Mycobacterium tuberculosis stress response factor SigH plays a crucial role in modulating the pathogen's response to heat, oxidative-stress, envelope damage and hypoxia. We hypothesized that the lack of this key stress response factor would alter the interaction between the pathogen and its host cells. We compared the interaction of Mtb, Mtb:Δ-sigH and a strain where the mutation had been genetically complemented (Mtb: Δ-sigH:CO) with primary rhesus macaque bone marrow derived macrophages (Rh-BMDMs). The expression of numerous inducible and homeostatic (CCL) β-chemokines and several apoptotic markers was induced to higher levels in the cells infected with Mtb:Δ-sigH, relative to Mtb or the complemented strain. The differential expression of these genes manifested into functional differences in chemotaxis and apoptosis in cells infected with these two strains. The mutant strain also exhibited reduced late-stage survival in Rh-BMDMs. We hypothesize that the product of one or more SigH-dependent genes may modulate the innate interaction of Mtb with host cells, effectively reducing the chemokine-mediated recruitment of immune effector cells, apoptosis of infected monocytes and enhancing the long-term survival and replication of the pathogen in this milieu The significantly higher induction of Prostaglandin Synthetase 2 (PTGS2 or COX2) in Rh-BMDMs infected with Mtb relative to Mtb: Δ-sigH may explain reduced apoptosis in Mtb-infected cells, as PTGS2 is known to inhibit p53-dependent apoptosis.The SigH-regulon modulates the innate interaction of Mtb with host phagocytes, perhaps as part of a strategy to limit its clearance and prolong its survival. The SigH regulon appears to be required to modulate innate immune responses directed against Mtb. 相似文献
986.
Manoj Kumar Anoop Kumar Shukla Harpal Singh Rakesh Tuli 《Journal of biotechnology》2009,140(3-4):143-148
Transgenic cotton lines were developed for high-level expression of a synthetic cry1EC gene from a wound inducible promoter. The tobacco pathogenesis related promoter PR-1a was modified by placing CaMV35S promoter on its upstream in reverse orientation. The resultant chimeric promoter CaMV35S(r)PR-1a expressed constitutively and was further up-regulated at the site of feeding by insects. It was induced more rapidly by treatment with salicylic acid (SA). The CaMV35S(r)PR-1a cry1EC expressing transgenic lines of cotton showed 100% mortality of Spodoptera litura larvae. The tightly regulated low-level expression of PR-1a was modified to a highly expressing constitutive expression by CaMV35S placed in reverse orientation. Salicylic acid treatment and wounding enhanced the expression further by the chimeric promoter. The leaves expressed more δ-endotoxin around the sites of insect bites. The levels of expression and induction varied among different transgenic lines, suggesting position effect. Some of the transgenic lines that expressed Cry1EC from the chimeric promoter at a low level also showed 100% mortality when induced with salicylic acid. A highly expressing insect bite and wound inducible promoter is desirable for developing insect resistant transgenic plants. 相似文献
987.
Gene amplification is prevalent in many eukaryotes and has been found linked to various phenomena such as ontogenesis, carcinogenesis,
in vitro culturing, neoplasia and drug resistance. Earlier, we reported a novel B chromosome in Plantago lagopus L., which was found to have arisen as a result of massive amplification of 5S rDNA. In addition, the chromosome is also composed
of 45S rDNA and transposable elements. While the importance of gene amplification cannot be underestimated, its mechanism
of origin is still unclear. Therefore, the aim of the present study was to determine whether amplification can be reactivated
in the novel B chromosome. For this purpose, in vitro culture was used as stress. Three modes of tissue culture, i.e., direct,
indirect and somatic embryogenesis were used for raising in vitro cultures. The variations due to genetic and epigenetic mechanisms
were assessed in regenerants using molecular techniques, namely, PCR-RFLP, SSAP and MSAP. The retrotransposon-based molecular
markers were applied to detect the polymorphism within transposable elements of in vitro regenerated and mother plants. We
detected the variations that may be due to genetic changes either because of element recombination or activation of transposable
elements which can lead to increase in the copy number. MSAP analysis revealed the differences in the DNA methylation pattern
of the regenerants derived from novel chromosome bearing mother plants. Some regenerated plants were associated with increase
and decrease in DNA methylation of both internal and external cytosine of the CCGG sequence. 相似文献
988.
We report the design of an oligonucleotide sensor for the detection of point mutation associated with sickle cell disease. The sensor was based on luminescence resonance energy transfer between a donor and an acceptor. Photon upconverting nanoparticles (NaYF(4) doped with Yb(3+) and Er(3+)) were used as the donor and a conventional fluorophore, N,N,N',N'-tetramethyl-6-carboxyrhodamine (TAMRA), as the acceptor. The sensor could detect the perfectly matched target, in the background of the mismatched target or other oligonucleotides of random sequences. The detection limit of this sensor towards perfectly matched target was calculated to be 120 femtomoles, with no photobleaching. Oligonucleotide sensors of such design demonstrate high sensitivity and specificity. 相似文献
989.
990.
Glibenclamide (GL)-loaded microcapsules (MC) and transdermal patches (TDP) were formulated and in vitro and in vivo parameters compared to find out the best route of drug administration. The formulation TDP1 having a drug–polymer ratio 1:1
showed comparatively higher GL release and better permeation across mice skin (p < 0.05). From the comparative study, it was concluded that the transdermal system of GL produced better improvement compared
to oral microcapsule administration (p < 0.05). The transdermal system exhibited comparatively slow and continuous supply of GL at a desired rate to systemic circulation
avoiding metabolism, which improved day-to-day glycemic control in diabetic subjects. Transdermal system of GL exhibited better
control of hyperglycemia and prolonged plasma half-life by transdermal systems (9.6 ± 1.2 h) in comparison with oral microcapsule
(5.84 ± 2.1 h), indicating that the drug, when administered by transdermal systems, will remain in the body for a longer period.
From the glucose tolerance test, transdermal route effectively maintained the normoglycemic levels in contrast to the oral
group (MC1), which produced remarkable hypoglycemia ranging from −12.6 ± 2.1% to −18 ± 2.3%. The significantly high (p < 0.05) area under the curve values observed with transdermal system (1,346.2 ± 92.3 ng ml−1 h−1) also indicate increased bioavailability of the drug from these systems compared to the oral route (829.8 ± 76.4 ng ml−1 h−1). 相似文献