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Summary A number of compounds were screened for their effects on growth of the yeast cells ofHistoplasma capsulatum. Included were penicillin and related compounds, sulfhydryl inhibitors, various organic sulfur compounds recently synthesized for the first time, and compounds structurally related to the required metabolites, thiamine and cystine or cysteine. Cephalothin was the only one of the penicillin related compounds which inhibited growth. This occurred only when a high concentration (8.3 × 10–4 M) was used. Of the analogues of cystine tested, allylglycine had the greatest inhibitory effect on growth of the yeast cells in the synthetic medium, but it failed to inhibit growth in a complex medium containing peptones and plasma. Among the sulfhydryl inhibitors, the maleimides were the most effective, producing complete inhibition of growth in the peptone medium at 10µg/ml or less. At subinhibitory concentrations the cultures tended to become mycelial. The action of the maleimides was reversed by cystine over a range of concentrations. At low concentrations, some of the disulfide derivatives of thiamine stimulated growth equally as well as thiamine, but at concentrations of 100 to 150µg/ml, they completely inhibited growth. On the basis of results obtained to date, three classes of the new organic sulfur compounds being tested offer promise as sources of potentially useful chemotherapeutic agents. These classes, which differ widely in structure, are as follows: the benzyl decylaminoethyl disulfides, the acyl disulfides, and the trithiopercarbamates.This investigation was supported by Public Health Service Research Grant AI-03524 from the National Institute of Allergy and Infectious Diseases. 相似文献
3.
The Arabidopsis MALE STERILITY 2 protein shares similarity with reductases in elongation/condensation complexes 总被引:16,自引:0,他引:16
Mark G.M. Aarts Rachel Hodge Kriton Kalantidis Dion Florack Zoe A. Wilson Bernard J. Mulligan Willem J. Stiekema Rod Scott y Pereira 《The Plant journal : for cell and molecular biology》1997,12(3):615-623
The Arabidopsis thaliana MALE STERILITY 2 ( MS2 ) gene product is involved in male gametogenesis. The first abnormalities in pollen development of ms2 mutants are seen at the stage in microsporogenesis when microspores are released from tetrads. Expression of the MS2 gene is observed in tapetum of wild-type flowers at, and shortly after, the release of microspores from tetrads. The MS2 promoter controls GUS expression at a comparable stage in the tapetum of transgenic tobacco containing an MS2 promoter–GUS fusion. The occasional pollen grains produced by mutant ms2 plants have very thin pollen walls. They are also sensitive to acetolysis treatment, which is a test for the presence of an exine layer. The MS2 gene product shows sequence similarity to a jojoba protein that converts wax fatty acids to fatty alcohols. A possible function of the MS2 protein as a fatty acyl reductase in the formation of pollen wall substances is discussed. 相似文献
4.
Zoe S. Davies Richard J. Gilbert Roger J. Merry Douglas B. Kell Michael K. Theodorou Gareth W. Griffith 《Applied microbiology》2000,66(4):1435-1443
The enormous variety of substances which may be added to forage in order to manipulate and improve the ensilage process presents an empirical, combinatorial optimization problem of great complexity. To investigate the utility of genetic algorithms for designing effective silage additive combinations, a series of small-scale proof of principle silage experiments were performed with fresh ryegrass. Having established that significant biochemical changes occur over an ensilage period as short as 2 days, we performed a series of experiments in which we used 50 silage additive combinations (prepared by using eight bacterial and other additives, each of which was added at six different levels, including zero [i.e., no additive]). The decrease in pH, the increase in lactate concentration, and the free amino acid concentration were measured after 2 days and used to calculate a “fitness” value that indicated the quality of the silage (compared to a control silage made without additives). This analysis also included a “cost” element to account for different total additive levels. In the initial experiment additive levels were selected randomly, but subsequently a genetic algorithm program was used to suggest new additive combinations based on the fitness values determined in the preceding experiments. The result was very efficient selection for silages in which large decreases in pH and high levels of lactate occurred along with low levels of free amino acids. During the series of five experiments, each of which comprised 50 treatments, there was a steady increase in the amount of lactate that accumulated; the best treatment combination was that used in the last experiment, which produced 4.6 times more lactate than the untreated silage. The additive combinations that were found to yield the highest fitness values in the final (fifth) experiment were assessed to determine a range of biochemical and microbiological quality parameters during full-term silage fermentation. We found that these combinations compared favorably both with uninoculated silage and with a commercial silage additive. The evolutionary computing methods described here are a convenient and efficient approach for designing silage additives. 相似文献
5.
Hydraulic redistribution affects modeled carbon cycling via soil microbial activity and suppressed fire 下载免费PDF全文
Congsheng Fu Guiling Wang Kenneth Bible Michael L. Goulden Scott R. Saleska Russell L. Scott Zoe G. Cardon 《Global Change Biology》2018,24(8):3472-3485
Hydraulic redistribution (HR) of water from moist to drier soils, through plant roots, occurs world‐wide in seasonally dry ecosystems. Although the influence of HR on landscape hydrology and plant water use has been amply demonstrated, HR's effects on microbe‐controlled processes sensitive to soil moisture, including carbon and nutrient cycling at ecosystem scales, remain difficult to observe in the field and have not been integrated into a predictive framework. We incorporated a representation of HR into the Community Land Model (CLM4.5) and found the new model improved predictions of water, energy, and system‐scale carbon fluxes observed by eddy covariance at four seasonally dry yet ecologically diverse temperate and tropical AmeriFlux sites. Modeled plant productivity and microbial activities were differentially stimulated by upward HR, resulting at times in increased plant demand outstripping increased nutrient supply. Modeled plant productivity and microbial activities were diminished by downward HR. Overall, inclusion of HR tended to increase modeled annual ecosystem uptake of CO2 (or reduce annual CO2 release to the atmosphere). Moreover, engagement of CLM4.5′s ground‐truthed fire module indicated that though HR increased modeled fuel load at all four sites, upward HR also moistened surface soil and hydrated vegetation sufficiently to limit the modeled spread of dry season fire and concomitant very large CO2 emissions to the atmosphere. Historically, fire has been a dominant ecological force in many seasonally dry ecosystems, and intensification of soil drought and altered precipitation regimes are expected for seasonally dry ecosystems in the future. HR may play an increasingly important role mitigating development of extreme soil water potential gradients and associated limitations on plant and soil microbial activities, and may inhibit the spread of fire in seasonally dry ecosystems. 相似文献
6.
Lescano AR Blazes DL Montano SM Moran Z Naquira C Ramirez E Lie R Martin GJ Lescano AG Zunt JR 《PloS one》2008,3(9):e3274
With the rapidly increasing number of health care professionals seeking international research experience, comes an urgent need for enhanced capacity of host country institutional review boards (IRB) to review research proposals and ensure research activities are both ethical and relevant to the host country customs and needs. A successful combination of distance learning, interactive courses and expert course instructors has been applied in Peru since 2004 through collaborations between the U.S. Naval Medical Research Center Detachment, the University of Washington and the Department of Clinical Bioethics of the National Institutes of Health to provide training in ethical conduct of research to IRB members and researchers from Peru and other Latin American countries. All training activities were conducted under the auspices of the Peruvian National Institute of Health (INS), Ministry of Health. To date, 927 people from 12 different Latin American countries have participated in several of these training activities. In this article we describe our training model. 相似文献
7.
Yusuke Fukuda Maria F. Pazyra-Murphy Elizabeth S. Silagi Ozge E. Tasdemir-Yilmaz Yihang Li Lillian Rose Zoe C. Yeoh Nicholas E. Vangos Ezekiel A. Geffken Hyuk-Soo Seo Guillaume Adelmant Gregory H. Bird Loren D. Walensky Jarrod A. Marto Sirano Dhe-Paganon Rosalind A. Segal 《The Journal of cell biology》2021,220(1)
Complex neural circuitry requires stable connections formed by lengthy axons. To maintain these functional circuits, fast transport delivers RNAs to distal axons where they undergo local translation. However, the mechanism that enables long-distance transport of RNA granules is not yet understood. Here, we demonstrate that a complex containing RNA and the RNA-binding protein (RBP) SFPQ interacts selectively with a tetrameric kinesin containing the adaptor KLC1 and the motor KIF5A. We show that the binding of SFPQ to the KIF5A/KLC1 motor complex is required for axon survival and is impacted by KIF5A mutations that cause Charcot-Marie Tooth (CMT) disease. Moreover, therapeutic approaches that bypass the need for local translation of SFPQ-bound proteins prevent axon degeneration in CMT models. Collectively, these observations indicate that KIF5A-mediated SFPQ-RNA granule transport may be a key function disrupted in KIF5A-linked neurologic diseases and that replacing axonally translated proteins serves as a therapeutic approach to axonal degenerative disorders. 相似文献
8.
Aaron Brewer Zoe Harrold Elliot Chang Drew Gorman‐Lewis Fang‐Zhen Teng 《Geobiology》2020,18(2):225-236
Bacillus subtilis endospore‐mediated forsterite dissolution experiments were performed to assess the effects of cell surface reactivity on Mg isotope fractionation during chemical weathering. Endospores present a unique opportunity to study the isolated impact of cell surface reactivity because they exhibit extremely low metabolic activity. In abiotic control assays, 24Mg was preferentially released into solution during forsterite dissolution, producing an isotopically light liquid phase (δ26Mg = ?0.39 ± 0.06 to ?0.26 ± 0.09‰) relative to the initial mineral composition (δ26Mg = ?0.24 ± 0.03‰). The presence of endospores did not have an apparent effect on Mg isotope fractionation associated with the release of Mg from the solid into the aqueous phase. However, the endospore surfaces preferentially adsorbed 24Mg from the dissolution products, which resulted in relatively heavy aqueous Mg isotope compositions. These aqueous Mg isotope compositions increased proportional to the fraction of dissolved Mg that was adsorbed, with the highest measured δ26Mg (?0.08 ± 0.07‰) corresponding to the highest degree of adsorption (~76%). The Mg isotope composition of the adsorbed fraction was correspondingly light, at an average δ26Mg of ?0.49‰. Secondary mineral precipitation and Mg adsorption onto secondary minerals had a minimal effect on Mg isotopes at these experimental conditions. Results demonstrate the isolated effects of cell surface reactivity on Mg isotope fractionation separate from other common biological processes, such as metabolism and organic acid production. With further study, Mg isotopes could be used to elucidate the role of the biosphere on Mg cycling in the environment. 相似文献
9.
Theodora?Koromila Panagiotis?Georgoulias Zoe?Dailiana Evangelia?E?Ntzani Stavroula?Samara Chris?Chassanidis Vassiliki?Aleporou-Marinou Panagoula?KolliaEmail author 《Human genomics》2013,7(1):21
Background
Osteoporosis has a multifactorial pathogenesis characterized by a combination of low bone mass and increased fragility. In our study, we focused on the effects of polymorphisms in CER1 and DKK1 genes, recently reported as important susceptibility genes for osteoporosis, on bone mineral density (BMD) and bone markers in osteoporotic women. Our objective was to evaluate the effect of CER1 and DKK1 variations in 607 postmenopausal women. The entire DKK1 gene sequence and five selected CER1 SNPs were amplified and resequenced to assess whether there is a correlation between these genes and BMD, early menopause, and bone turnover markers in osteoporotic patients.Results
Osteoporotic women seem to suffer menopause 2 years earlier than the control group. The entire DKK1 gene sequence analysis revealed six variations. There was no correlation between the six DKK1 variations and osteoporosis, in contrast to the five common CER1 variations that were significantly associated with BMD. Additionally, osteoporotic patients with rs3747532 and rs7022304 CER1 variations had significantly higher serum levels of parathyroid hormone and calcitonin and lower serum levels of osteocalcin and IGF-1.Conclusions
No significant association between the studied DKK1 variations and osteoporosis was found, while CER1 variations seem to play a significant role in the determination of osteoporosis and a potential predictive role, combined with bone markers, in postmenopausal osteoporotic women.10.
Samuel J. Bolitho Sharon L. Naismith Pierre Salahuddin Zoe Terpening Ron R. Grunstein Simon J. G. Lewis 《PloS one》2013,8(11)