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排序方式: 共有158条查询结果,搜索用时 31 毫秒
1.
Jay C. D. Hinton Julie M. Sidebotham Lizbeth J. Hyman Michel C. M. Pérombelon George P. C. Salmond 《Molecular & general genetics : MGG》1989,217(1):141-148
Summary The blackleg pathogen Erwinia carotovora subsp. atroseptica (Eca) causes an economically important disease of potatoes. We selected a genetically amenable Eca strain for the genetic analysis of virulence. Tn5 mutagenesis was used to generate nine mutants which exhibited reduced virulence (Rvi-) of strain SCRI1043. Following physiological characterisation, mutants were divided into three classes: (1) auxotrophs; (2) extracellular enzyme mutants; and (3) a growth rate mutant. The isolation of these Rvi- mutants has allowed us to consider some factors that affect Eca virulence. 相似文献
2.
Lizbeth Castro-Concha Victor M. Loyola-Vargas José L. Chan Manuel L. Robert 《Plant Cell, Tissue and Organ Culture》1990,22(2):147-151
Agave tequilana stem explants were used to produce adventitious shoots under a set of different water potentials induced by different concentrations of gelrite in the medium. At high water potentials all shoots were vitrified; as the medium water potential became more negative the degree of vitrification decreased but the number of shoots per explant also diminished. The enzymes NADH and NAD-GDH (EC. 1.4.1.2) were measured along the water potential gradient. GDH activity was high in the non-vitrified tissues and decreased significantly in the vitrified ones.Abbreviations GDH
glutamate dehydrogenase
- MS
Murashige and Skoog medium
- MSO
methionine sulfoximine
- PVP
polyvinylpolypyrrolidone
- GS
glutamine synthetase
- GOGAT
glutamine: oxoglutarate amino transferase 相似文献
3.
Nine children with severe protein calorie malnutrition were studied regarding the frequency of sister chromatid exchanges (SCE's) in peripheral blood lymphocytes. The results showed that there was no significant difference between the number of SCE's in the malnourished children as compared to an adequate control group. An interesting finding was that the proportion of 3rd or subsequent division metaphases found in the malnourished children, was higher and significantly different from that seen in the control group. 相似文献
4.
Osvaldo Mutchinick Lizbeth Ruz María E. Gonsebatt Patricia Mauleón Rubén Lisker Guillermo García 《Human genetics》1981,59(2):137-140
Summary Induced and spontaneous structural chromosome aberrations (SCA) were studied in a child accidentally radiated with a high dose of 192Ir, and in three sibs with Fanconi's anemia, analyzing by separate first division metaphases (FDM) and second division metaphases (SDM). The results showed that the number of SCA, number of cells with aberrations, and SCA per cell were markedly higher in FDM in all patients.Furthermore, for some type of structural changes like dicentric chromosomes and chromatid interchanges, the differences were particularly striking. The importance of ascertaining FDM identified with proper techniques, for the study of the clastogenic effect of environmental agents and some aspects related to the differences in cytogenetic features found in diverse tissues in Fanconi's anemia are discussed. 相似文献
5.
Manuel Ruz Kelley R. Cavan William J. Bettger Peter W. F. Fischer Rosalind S. Gibson 《Biological trace element research》1992,34(2):197-212
This study examined the effect of diet-induced, marginal zinc deficiency for 7 wks in 15 men (aged 25.3 +/- 3.3 yrs; mean +/- SD) on selected indices of iron and copper status. The regimen involved low-zinc diets based on egg albumin and soy protein with added phytate and calcium such that mean [phytate]/[Zn] and [phytate] X [Ca]/[Zn] molar ratios were 209 and 4116, respectively, for 1 wk, followed by 70 and 2000, respectively, for 6 wks. Subjects were then repleted with 30 mg Zn/d for 2 wks. Plasma copper, Cu,Zn-superoxide dismutase (Cu,Zn-SOD) activity in plasma and red blood cells (RBC), hemoglobin, hematocrit, and serum ferritin were determined weekly on fasting blood samples. Significant reductions (p less than 0.05) after 7 wks in RBC Cu,Zn-superoxide dismutase (49.5 +/- 7.2 vs 33.6 +/- 6.3 U/mg Hb) and serum ferritin (69.2 +/- 38.7 vs 53.8 +/- 33.7 micrograms/L) occurred; no comparable decline was noted for plasma Cu, hemoglobin, or hematocrit. Significant (p less than 0.05) but less consistent changes were also observed in plasma superoxide dismutase activity. None of the changes were associated with the decreases in plasma, urinary and hair zinc concentrations, and alkaline phosphatase activity in RBC membranes. Results indicate that the biochemical iron and copper status of the subjects was marginally impaired, probably from the dietary regimen that induced marginal zinc deficiency. 相似文献
6.
Ivar M. McDonald Robert A. Mate F. Christopher Zusi Hong Huang Debra J. Post-Munson Meredith A. Ferrante Lizbeth Gallagher Robert L. Bertekap Ronald J. Knox Barbara J. Robertson David G. Harden Daniel G. Morgan Nicholas J. Lodge Steven I. Dworetzky Richard E. Olson John E. Macor 《Bioorganic & medicinal chemistry letters》2013,23(6):1684-1688
High throughput screening led to the identification of a novel series of quinolone α7 nicotinic acetylcholine receptor (nAChR) agonists. Optimization of an HTS hit (1) led to 4-phenyl-1-(quinuclidin-3-ylmethyl)quinolin-2(1H)-one, which was found to be potent and selective. Poor brain penetrance in this series was attributed to transporter-mediated efflux, which was in turn due to high pKa. A novel 4-fluoroquinuclidine significantly lowered the pKa of the quinuclidine moiety, reducing efflux as measured by a Caco-2 assay. 相似文献
7.
Corey R. Johnson Suresh Kumar Gorla Mandapati Kavitha Minjia Zhang Xiaoping Liu Boris Striepen Jan R. Mead Gregory D. Cuny Lizbeth Hedstrom 《Bioorganic & medicinal chemistry letters》2013,23(4):1004-1007
Cryptosporidium parvum (Cp) is a potential biowarfare agent and major cause of diarrhea and malnutrition. This protozoan parasite relies on inosine 5′-monophosphate dehydrogenase (IMPDH) for the production of guanine nucleotides. A CpIMPDH-selective N-aryl-3,4-dihydro-3-methyl-4-oxo-1-phthalazineacetamide inhibitor was previously identified in a high throughput screening campaign. Herein we report a structure–activity relationship study for the phthalazinone-based series that resulted in the discovery of benzofuranamide analogs that exhibit low nanomolar inhibition of CpIMPDH. In addition, the antiparasitic activity of select analogs in a Toxoplasma gondii model of C. parvum infection is also presented. 相似文献
8.
A minimal amount is known regarding the mechanisms underlying the potential benefits of extracurricular activities (ECAs) for adolescents’ psychological adjustment. This preliminary cross-sectional study, during which 512 undergraduates retrospectively reported information about high school ECAs, used structural equation modeling to show that feelings of mastery and creative self-efficacy partially explained relationships between past ECA involvement and current psychological adjustment (depression, anxiety, and well-being) as well as creative achievement, though results varied according to the type of ECAs examined. These findings support the importance of studying the specific processes that may account for the benefits of extracurricular involvement within and across activity domains. Future studies using longitudinal designs are needed to assess the causal nature of these findings. 相似文献
9.
Gonzalez-Herrera L Castillo-Zapata I Garcia-Escalante G Pinto-Escalante D 《Birth defects research. Part A, Clinical and molecular teratology》2007,79(8):622-626
BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) of the folate metabolism pathway is a candidate gene for neural tube defects (NTDs). Frequency of the second common polymorphism, A1298C, in the MTHFR gene is not well known in Mexico. Conflicting results exist regarding the association of A1298C-MTHFR with NTDs. One explanation for this controversy might be that alleles are differently distributed among various populations. The aim of the study was to determine the frequency of the A1298C-MTHFR polymorphism and its association with NTDs in a population of Yucatan, Mexico. METHODS: Genotyping was performed by use of polymerase chain reaction with restriction fragment length polymorphisms using MbOII endonuclease (PCR-RFLPs MbOII). Allele and genotype frequencies were compared between cases with NTDs, their mothers and fathers with matched controls based on an association analysis using EpiInfo software. RESULTS: A1298C genotypes were distributed according to Hardy-Weinberg expectations for all studied groups. Frequencies of allele C and heterozygous AC genotype were significantly higher in males (p = .006 and p = .011, respectively) in control group. Significant differences were not observed between cases and controls, except in mothers of NTD cases compared with mothers of healthy offspring for both allele C and heterozygous AC genotype (p = .009 and p = .01, respectively). CONCLUSIONS: The polymorphism A1298C-MTHFR is not associated with NTDs, except for mothers, suggesting only a maternal association with having NTD-affected offspring in the Yucatan population. The frequency of allele C in the control population was 10%, which is significantly lower than in other reported control populations worldwide (p < .01). 相似文献
10.