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1.
R. P. Pacumbaba J. G. Wutoh Sama Anne Eyango J. T. Tambong L. M. Nyochembeng 《Journal of Phytopathology》1992,135(4):265-273
Cocoyam is the second most important staple crop of Cameroon and root rot is a destructive disease of this plant. Pythium myriotylum (Pm), Fusarium solani (Fs), and Rhizoctonia solani (Rs) were isolated from the rhizosphere of root rot affected cocoyams and from the soil of a cocoyam experimental field plot temporarily devoid of same in Mamu, Cameroon. Pm was isolated from the above soil by the cocoyam leaf disc baits. Fs and Rs were also isolated from the same soils by the water dilution method and from the roots of diseased cocoyams but were always associated with mycelial growth of Pm. Pathogenicity of Pm and in combinations with Fs or Rs or Fs + Rs all developed cocoyam root rot disease (CRRD) symptoms on 3– and 7–month old cocoyam plantlets 2–7 days after inoculation. Symptoms included rotted roots and wilting with general chlorosis of inoculated plantlets. No symptoms of CRRD were noted on cocoyam plantlets inoculated with Fs, Rs, Fs + Rs, and distilled water. Results indicated that CRRD is not caused by several pathogens but only by Pm. Pm isolates from the soils and roots of diseased cocoyams and those maintained in the ROTREP laboratory have significantly bigger diameter of mycelial colony growth in 24 h–period at 31 °C on lima bean sucrose agar, V–8 juice sucrose agar, and potato sucrose agar than on potato dextrose agar and 2 % water agar. The cocoyam plantlets were raised axenically from tissue culture of explants in the laboratory. 相似文献
2.
Biochemical and genetic characterization of three hamster cell mutants resistant to diphtheria toxin 总被引:2,自引:0,他引:2
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RK Draper D Chin D Eurey-Owens IE Scheffler MI Simon 《The Journal of cell biology》1979,83(1):116-125
We describe here three different hamster cell mutants which are resistant to diphtheria toxin and which provide models for investigating some of the functions required by the toxin inactivates elongation factor 2 (EF-2). Cell-free extracts from mutants Dtx(r)-3 was codominant. The evidence suggests that the codominant phenotype is the result of a mutation in a gene coding for EF-2. The recessive phenotype might arise by alteration of an enzyme which modifies the structure of EF-2 so that it becomes a substrate for reaction with the toxin. Another mutant, Dtx(r)-2, contained EF-2 that was sensitive to the toxin and this phenotype was recessive. Pseudomonas aeruginosa exotoxin is known to inactivate EF-2 as does diphtheria toxin and we tested the mutants for cross-resistance to pseudomonas exotoxin. Dtx(r)-1 and Dtx(r)-3 were cross-resistant while Dtx(r)-2 was not. It is known that diphtheria toxin does not penetrate to the cytoplasm of mouse cells and that these cell have a naturally occurring phenotype of diphtheria toxin resistance. We fused each of the mutants with mouse 3T3 cells and measured the resistance. We fused each of the mutants with mouse 3T3 cells and measured the resistance of the hybrid cells to diphtheria toxin. Intraspecies hybrids containing the genome of mutants Dtx(r)-1 and Dtx(r)-3 had some resistance while those formed with Dtx(r)-2 were as sensitive as hybrids derived from fusions between wild-type hamster cells and mouse 3T3 cells. 相似文献
3.
A M Morselli E Roda A Roda C Sama R Aldini G Mazzella D Festi F Bazzoli E Sarti L Barbara 《Bollettino della Società italiana di biologia sperimentale》1979,55(15):1527-1533
A multicompartmental model was applied to the study of the plasmatic and biliary kinetics of the 14C-Cholic acid intravenously injected into a baboon in normal and cholestatic condition. For the evaluation of transfer rates FORTAN IV procedures were used, utilizing Powell method. The degree of fitting was: in normal condition in serum 7% for free and 35% for conjugated Cholic acid, while in bile 5% and 4% respectively; in serum in cholestatic condition 7% for free and 12% for conjugates. The high degree of fitting and reliable estimation of transfer rates suggest that the multicompartmental model applied represents most likely the physio-pathological conditions studied. 相似文献
4.
A sensitive and specific radioimmunoassay for glycine and taurine conjugates of lithocholic acid (CLCA) has been developed. 3H-glycolithocholic acid (S.A. = 17Ci/mmol) was used as tracer. Separation of free from antibody-bound bile acid was carried out using ammonium sulphate (saturated solution). The antiserum showed high specificity for both glyco and tauro conjugated lithocholate (100% cross reaction) and lithocholic acid (25% cross reaction). The sensitivity of the assay (1 pmole/tube), was adequate for measuring CLCA in peripheral blood and hepatic tissue in man. 相似文献
5.
本文利用激光散斑屈光测试系统详细探讨了夜近视(night myopia)的产生机制。夜近视在环境亮度降低到产生暗视觉时出现,并随亮度继续降低而增大,平均值为1.35D。实验证明眼睛球差和色差不是造成夜近视的主要因素。夜近视数值在暗适应过程中呈增大的趋势。在暗视觉时,由于视野中缺少适宜的刺激,眼睛处于暗焦(dark focus)休止状态,这是造成夜近视的主要原因。 相似文献
6.
Lingyan Xu Xinran Ma Narendra Verma Luce Perie Jay Pendse Sama Shamloo Anne Marie Josephson Dongmei Wang Jin Qiu Mingwei Guo Xiaodan Ping Michele Allen Audrey Noguchi Danielle Springer Fei Shen Caizhi Liu Shiwei Zhang Lingyu Li Jin Li Junjie Xiao Jian Lu Zhenyu Du Jian Luo Jose O. Aleman Philipp Leucht Elisabetta Mueller 《Aging cell》2020,19(11)
7.
Wei Li Jianhua Li Andrew E Sama Haichao Wang 《Molecular medicine (Cambridge, Mass.)》2013,19(1):203-211
The pathogen- and damage-associated molecular patterns (for example, bacterial endotoxin and adenosine 5′-triphosphate [ATP]) activate the double-stranded RNA-activated protein kinase R (PKR) to trigger the inflammasome-dependent high mobility group box 1 (HMGB1) release. Extracellular ATP contributes to the inflammasome activation through binding to the plasma membrane purinergic P2X7 receptor (P2X7R), triggering the opening of P2X7R channels and the pannexin-1 (panx-1) hemichannels permeable for larger molecules up to 900 daltons. It was previously unknown whether panx-1 channel blockers can abrogate lipopolysaccharide (LPS)-induced PKR activation and HMGB1 release in innate immune cells. Here we demonstrated that a major gancao (licorice) component (glycyrrhizin, or glycyrrhizic acid) derivative, carbenoxolone (CBX), dose dependently abrogated LPS-induced HMGB1 release in macrophage cultures with an estimated IC50 ≈ 5 μmol/L. In an animal model of polymicrobial sepsis (induced by cecal ligation and puncture [CLP]), repetitive CBX administration beginning 24 h after CLP led to a significant reduction of circulating and peritoneal HMGB1 levels, and promoted a significant increase in animal survival rates. As did P2X7R antagonists (for example, oxidized ATP, oATP), CBX also effectively attenuated LPS-induced P2X7R/panx-1 channel activation (as judged by Lucifer Yellow dye uptake) and PKR phosphorylation in primary peritoneal macrophages. Collectively, these results suggested that CBX blocks LPS-induced HMGB1 release possibly through impairing PKR activation, supporting the involvement of PKR in the regulation of HMGB1 release. 相似文献
8.
Desiree?M?Baron Laura?J?Kaushansky Catherine?L?Ward Reddy?Ranjith?K?Sama Ru-Ju?Chian Kristin?J?Boggio Alexandre?J?C?Quaresma Jeffrey?A?Nickerson Daryl?A?BoscoEmail author 《Molecular neurodegeneration》2013,8(1):30
Background
Amyotrophic lateral sclerosis (ALS)-linked fused in sarcoma/translocated in liposarcoma (FUS/TLS or FUS) is concentrated within cytoplasmic stress granules under conditions of induced stress. Since only the mutants, but not the endogenous wild-type FUS, are associated with stress granules under most of the stress conditions reported to date, the relationship between FUS and stress granules represents a mutant-specific phenotype and thus may be of significance in mutant-induced pathogenesis. While the association of mutant-FUS with stress granules is well established, the effect of the mutant protein on stress granules has not been examined. Here we investigated the effect of mutant-FUS on stress granule formation and dynamics under conditions of oxidative stress.Results
We found that expression of mutant-FUS delays the assembly of stress granules. However, once stress granules containing mutant-FUS are formed, they are more dynamic, larger and more abundant compared to stress granules lacking FUS. Once stress is removed, stress granules disassemble more rapidly in cells expressing mutant-FUS. These effects directly correlate with the degree of mutant-FUS cytoplasmic localization, which is induced by mutations in the nuclear localization signal of the protein. We also determine that the RGG domains within FUS play a key role in its association to stress granules. While there has been speculation that arginine methylation within these RGG domains modulates the incorporation of FUS into stress granules, our results demonstrate that this post-translational modification is not involved.Conclusions
Our results indicate that mutant-FUS alters the dynamic properties of stress granules, which is consistent with a gain-of-toxic mechanism for mutant-FUS in stress granule assembly and cellular stress response.9.
10.
Josephine D’Urban Jackson Sama Zefania Sebastien Moehy Andrew J Bamford Michael W Bruford Tamás Székely 《Ostrich》2019,90(4):315-326
The Madagascar Jacana Actophilornis albinucha (Jacanidae) is an endemic shorebird found in the threatened wetlands of western Madagascar. This species is presumed to exhibit classical polyandry; however, few data are available to support that assumption. More generally, a lack of basic understanding of this species hinders conservation efforts. We conducted the most extensive study of the Madagascar Jacana to date, and report on its: 1) distribution, population size and density; 2) degree of sexual size dimorphism; and 3) phylogenetic position. The surveys were conducted at 54 lakes, between January and October in 2016. Madagascar Jacana were found at 22 lakes, and within these were distributed at a mean density of 3.5 ± 0.74 [SE] individuals per hectare of surveyed habitat. We estimate the global population size to be between 975 and 2 064 individuals, and habitat destruction appears to be the main threat to the species. Females were significantly larger than males, consistent with reports for other Jacanidae species. Using a mitochondrial DNA fragment, we expanded the Jacanidae genetic phylogeny, and confirmed that Madagascar Jacana is the sister species to the African Jacana Actophilornis africanus. Further studies are urgently needed to thoroughly re-assess the threat status and population trend of the Madagascar Jacana. 相似文献