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Characterization of differentiated quiescent and nonquiescent cells in yeast stationary-phase cultures 总被引:2,自引:0,他引:2
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Aragon AD Rodriguez AL Meirelles O Roy S Davidson GS Tapia PH Allen C Joe R Benn D Werner-Washburne M 《Molecular biology of the cell》2008,19(3):1271-1280
Cells in glucose-limited Saccharomyces cerevisiae cultures differentiate into quiescent (Q) and nonquiescent (NQ) fractions before entering stationary phase. To understand this differentiation, Q and NQ cells from 101 deletion-mutant strains were tested for viability and reproductive capacity. Eleven mutants that affected one or both phenotypes in Q or NQ fractions were identified. NQ fractions exhibit a high level of petite colonies, and nine mutants affecting this phenotype were identified. Microarray analysis revealed >1300 mRNAs distinguished Q from NQ fractions. Q cell-specific mRNAs encode proteins involved in membrane maintenance, oxidative stress response, and signal transduction. NQ-cell mRNAs, consistent with apoptosis in these cells, encode proteins involved in Ty-element transposition and DNA recombination. More than 2000 protease-released mRNAs were identified only in Q cells, consistent with these cells being physiologically poised to respond to environmental changes. Our results indicate that Q and NQ cells differentiate significantly, with Q cells providing genomic stability and NQ cells providing nutrients to Q cells and a regular source of genetic diversity through mutation and transposition. These studies are relevant to chronological aging, cell cycle, and genome evolution, and they provide insight into complex responses that even simple organisms have to starvation. 相似文献
54.
Loza-Mejía MA Maldonado-Hernández K Rodríguez-Hernández F Rodríguez-Sotres R González-Sánchez I Quintero A Solano JD Lira-Rocha A 《Bioorganic & medicinal chemistry》2008,16(3):1142-1149
A series of novel alkylamino and 9-anilinothiazolo[5,4-b]quinolines were synthesized as potential antitumoral agents. The in vitro cytotoxicity of these compounds was evaluated on several cell lines. The inclusion of electron-withdrawn/acceptor hydrogen-bond groups at position 3' of the anilino ring and the presence of an alkylamino chain on the tricyclic framework (regardless of its position) seem to be structural features relevant to cytotoxic activity. 相似文献
55.
Antonio Fiorentino Brigida D'Abrosca Assunta Esposito Angelina Izzo Maria Teresa Pascarella Grazia D'Angelo Pietro Monaco 《Biochemical Systematics and Ecology》2009,37(4):349-353
The allelopathic effects of neo-clerodane diterpenes, isolated from Teucrium chamaedrys (L.), have been evaluated on the seed germination and seedling growth of four coexisting Mediterranean species (Dactylis hispanica, Petrorhagia velutina, Phleum subulatum and Petrorhagia saxifraga) and two cosmopolitan weeds (Amaranthus retroflexus and Avena fatua). All of the structures have been elucidated on the basis of their spectroscopic features. The bioassays data, analyzed by principal component analysis, showed more negative effects on weeds respect to coexisting species. Moreover D. hispanica, P. velutina, P. subulatum showed both stimulating or inhibiting effects depending on the type of metabolite and the concentration used in the test. 相似文献
56.
Inma R. Cantalapiedra Angelina Peñaranda Lluis Mont Blas Echebarria 《Journal of theoretical biology》2009,259(4):850-859
Dispersion of action potential repolarization is known to be an important arrhythmogenic factor in cardiopathies such as Brugada syndrome. In this work, we analyze the effect of a variation in sodium current (INa) inactivation and a heterogeneous rise of transient outward current (Ito) in the probability of reentry in epicardial tissue. We use the Luo-Rudy model of epicardial ventricular action potential to study wave propagation in a one-dimensional fiber. Spatial dispersion in repolarization is introduced by splitting the fiber into zones with different strength of Ito. We then analyze the pro-arrhythmic effect of a variation in the relaxation time and steady-state of the sodium channel fast inactivating gate h. We quantify the probability of reentry measuring the percentage of reexcitations that occurs in 200 beats. We find that, for high stimulation rates, this percentage is negligible, but increases notably for pacing periods above 700 ms. Surprisingly, with decreasing INa inactivation time, the percentage of reexcitations does not grow monotonically, but presents vulnerable windows, separated by values of the INa inactivation speed-up where reexcitation does not occur. By increasing the strength of L-type calcium current ICaL above a certain threshold, reexcitation disappears. Finally, we show the formation of reentry in stimulated two-dimensional epicardial tissue with modified INa kinetics and Ito heterogeneity. Thus, we confirm that while Ito dispersion is necessary for phase-2 reentry, altered sodium inactivation kinetics influences the probability of reexcitation in a highly nonlinear fashion. 相似文献
57.
Logistic regression is often used to help make medical decisions with binary outcomes. Here we evaluate the use of several methods for selection of variables in logistic regression. We use a large dataset to predict the diagnosis of myocardial infarction in patients reporting to an emergency room with chest pain. Our results indicate that some of the examined methods are well suited for variable selection in logistic regression and that our model, and our myocardial infarction risk calculator, can be an additional tool to aid physicians in myocardial infarction diagnosis. 相似文献
58.
Nicholas McCaul Corey M. Porter Anouk Becker Chih-Hang Anthony Tang Charlotte Wijne Bhaskar Chatterjee Djenet Bousbaine Angelina Bilate Chih-Chi Andrew Hu Hidde Ploegh Matthias C. Truttmann 《The Journal of biological chemistry》2021,297(3)
Fic domain-containing AMP transferases (fic AMPylases) are conserved enzymes that catalyze the covalent transfer of AMP to proteins. This posttranslational modification regulates the function of several proteins, including the ER-resident chaperone Grp78/BiP. Here we introduce a mouse FICD (mFICD) AMPylase knockout mouse model to study fic AMPylase function in vertebrates. We find that mFICD deficiency is well tolerated in unstressed mice. We also show that mFICD-deficient mouse embryonic fibroblasts are depleted of AMPylated proteins. mFICD deletion alters protein synthesis and secretion in splenocytes, including that of IgM, an antibody secreted early during infections, and the proinflammatory cytokine IL-1β, without affecting the unfolded protein response. Finally, we demonstrate that visual nonspatial short-term learning is stronger in old mFICD−/− mice than in wild-type controls while other measures of cognition, memory, and learning are unaffected. Together, our results suggest a role for mFICD in adaptive immunity and neuronal plasticity in vivo. 相似文献
59.
Constance Dubuc Sandra Winters William L. Allen Lauren J. N. Brent Julie Cascio Dario Maestripieri Angelina V. Ruiz-Lambides Anja Widdig James P. Higham 《Proceedings. Biological sciences / The Royal Society》2014,281(1794)
Sexual selection promotes the prevalence of heritable traits that increase an individual''s reproductive rate. Despite theoretically strong directional selection, sexually selected traits can show inter-individual variation. Here, we investigate whether red skin ornamentation, a rare example of a male mammalian trait involved in mate attraction, influences fecundity and is heritable in rhesus macaques (Macaca mulatta), and explore the mechanisms that are involved in maintaining trait variation. Interestingly, the trait is expressed by and is attractive to both sexes. We collected facial images of 266 free-ranging individuals and modelled skin redness and darkness to rhesus macaque vision. We used 20 years of genetic parentage data to calculate selection gradients on the trait and perform heritability analyses. Results show that males who were both darkly coloured and high-ranking enjoyed higher fecundity. Female skin redness was positively linked to fecundity, although it remains unclear whether this influences male selectiveness. Heritability explained 10–15% of the variation in redness and darkness, and up to 30% for skin darkness when sexes are considered separately, suggesting sex-influenced inheritance. Our results suggest that inter-individual variation is maintained through condition-dependence, with an added effect of balancing selection on male skin darkness, providing rare evidence for a mammalian trait selected through inter-sexual selection. 相似文献
60.
Luigi Michaud Angelina Lo Giudice Mohamed Mysara Pieter Monsieurs Carmela Raffa Natalie Leys Stefano Amalfitano Rob Van Houdt 《PloS one》2014,9(8)
The cryosphere is an integral part of the global climate system and one of the major habitable ecosystems of Earth''s biosphere. These permanently frozen environments harbor diverse, viable and metabolically active microbial populations that represent almost all the major phylogenetic groups. In this study, we investigated the microbial diversity in the surface snow surrounding the Concordia Research Station on the High Antarctic Plateau through a polyphasic approach, including direct prokaryotic quantification by flow cytometry and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH), and phylogenetic identification by 16S RNA gene clone library sequencing and 454 16S amplicon pyrosequencing. Although the microbial abundance was low (<103 cells/ml of snowmelt), concordant results were obtained with the different techniques. The microbial community was mainly composed of members of the Alpha-proteobacteria class (e.g. Kiloniellaceae and Rhodobacteraceae), which is one of the most well-represented bacterial groups in marine habitats, Bacteroidetes (e.g. Cryomorphaceae and Flavobacteriaceae) and Cyanobacteria. Based on our results, polar microorganisms could not only be considered as deposited airborne particles, but as an active component of the snowpack ecology of the High Antarctic Plateau. 相似文献