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1.
A. M. A. Wolters H. C. H. Schoenmakers J. J. M. van der Meulen-Muisers E. van der Knaap E. H. M. Derks M. Koornneef A. Zelcer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,83(2):225-232
Summary This paper describes the analysis of the elimination of potato DNA from potato-tomato somatic cell hybrids. The hybrids were obtained by fusion of protoplasts of a cytoplasmic albino tomato genotype with leaf mesophyll protoplasts of a potato genotype carrying the -glucuronidase (GUS) gene of Escherichia coli. The potato protoplasts were either isolated from unirradiated plants or from plants irradiated with 50 or 500 Gy of -rays. Green calli were selected as putative fusion products. The hybridity of these calli was confirmed by isoenzyme analysis. All of the green calli tested contained a potato-specific chloroplast DNA restriction fragment, and most of the calli analysed were positive for -glucuronidase activity. In 72 of the hybrid calli we determined the percentage of potato nuclear DNA using species-specific probes. All of the tested green calli contained a considerable amount of potato genomic DNA, irrespective of the dose of irradiation of the potato parent. The limited degree of potato DNA elimination and the absence of true cybrids are discussed. 相似文献
2.
Annie Conter Dominique Dupouy Christine Delteil Hubert Planel 《Archives of microbiology》1986,144(3):286-290
Previous results from this laboratory have shown that very low chronic doses of gamma radiation can stimulate proliferation of the Cyanobacterium Synechococcus lividus. This modification of cell proliferation occurred during the first doubling. In this paper, we have compared the metabolism of cells cultivated in a normal environment or under chronic irradiation. Incubation of the cells in a new medium induced a high superoxide dismutase (EC 1.15.1.1, SOD) activity at the 18th hour and a degradation of phycocyanin, thus demonstrating that cells were submitted to a photooxidative stress. This increase in superoxide dismutase activity was followed by concomittant peaks of glutathione reductase (EC 1.6.4.2, GR) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6P-DH) at the 24th hour. Irradiated cultures at a dose of 53.5 mGray/year show an earlier and higher peak of SOD, GR, and G6P-DH. In a second stage, cultures showed an earlier onset of photosynthesis under irradiation, as evidenced by an increase in pigment content and an enhancement of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13, GAP-DH). These results show that the radiostimulation is related to the activation of enzymes protecting against peroxides that were induced under oxidative circumstances and to the activation of a glucose catabolism via the oxidative pentose phosphate pathway.Abbreviations mGy
milli-Gray
- SOD
superoxide dismutase
- G6P-DH
glucose-6-phosphate dehydrogenase
- GAP-DH
glycer-aldehyde-3-phosphate dehydrogenase
- GSSG
oxidized glutathione 相似文献
3.
Donato Torre Giulio Ferrario Giancarla Bonetta Lorenza Perversi Roberto Tambini Filippo Speranza 《FEMS immunology and medical microbiology》1994,9(3):183-188
Abstract Several studies have demonstrated that Bordetella pertussis has the ability to enter and survive intracellularly within human polymorphonuclear leukocytes (PMNL) and human monocytes/macrophages. The effects of human recombinant gamma interferon (IFN-γ) on the survival of B. pertussis in PMNL and human monocytes, and on the oxidative burst activity of PMNL and human monocytes in response to B. pertussis were assessed in this study. IFN-γ partially increased intracellular killing of phagocytosed B. pertussis in human monocytes, as determined by an orange acridine-crystal violet assay. In contrast, IFN-γ did not enhance intracellular killing of B. pertussis in PMNL. No significant increase of superoxide production was noted in human monocytes in response to B. pertussis when stimulated with various concentrations of IFN-γ. The partial increase of B. pertussis killing by IFN-γ within monocytes, together with poor production of superoxide may explain how B. pertussis can survive within human phagocytic cells, and thus cause a more prolonged course of the disease. 相似文献
4.
Y. S. Xu M. Murto R. Dunckley M. G. K. Jones E. Pehu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,85(6-7):729-734
Summary Asymmetric somatic hybrids were obtained by fusion of Solanum tuberosum (PDH40) protoplasts with 300- or 500-Gy irradiated protoplasts of S. brevidens. These radiation doses were sufficient to prevent the growth of the S. brevidens protoplasts. Putative hybrids were selected on the basis of phenotype from regenerated shoots and identified with a S. brevidens-specific probe. From these, 31 asymmetric hybrids were confirmed by morphological characteristics, isoenzyme patterns and RFLP analysis. The morphology of the asymmetric hybrids was intermediate between that of S. tuberosum and symmetric hybrids of both species (obtained without irradiation treatment). Chromosome counts from 17 asymmetric hybrids showed that the chromosome number of the hybrids ranged from 31 to 64. The asymmetric hybrids probably had one or two genome complements (i.e. either 24 or 48 chromosomes) from S. tuberosum and 7–22 chromosomes from S. brevidens. There was no clear correlation between the radiation dose and the degree of elimination of the S. brevidens genome. 相似文献
5.
Ziheng Yang 《Journal of molecular evolution》1995,40(6):689-697
Several maximum likelihood and distance matrix methods for estimating phylogenetic trees from homologous DNA sequences were compared when substitution rates at sites were assumed to follow a gamma distribution. Computer simulations were performed to estimate the probabilities that various tree estimation methods recover the true tree topology. The case of four species was considered, and a few combinations of parameters were examined. Attention was applied to discriminating among different sources of error in tree reconstruction, i.e., the inconsistency of the tree estimation method, the sampling error in the estimated tree due to limited sequence length, and the sampling error in the estimated probability due to the number of simulations being limited. Compared to the least squares method based on pairwise distance estimates, the joint likelihood analysis is found to be more robust when rate variation over sites is present but ignored and an assumption is thus violated. With limited data, the likelihood method has a much higher probability of recovering the true tree and is therefore more efficient than the least squares method. The concept of statistical consistency of a tree estimation method and its implications were explored, and it is suggested that, while the efficiency (or sampling error) of a tree estimation method is a very important property, statistical consistency of the method over a wide range of, if not all, parameter values is prerequisite. 相似文献
6.
A. Danin 《Plant Ecology》1978,36(2):83-93
Summary Lists of vascular plant species for each of the 12 ecological districts of Sinai were prepared. In all 78,000 observations on altogether 812 species were analyzed. The number of districts where each species occurred was also counted. Linear regressions were calculated for the log-transformed values of species/area, species/altitude and multiple regression of species on both area and altitude.The regression of species on area for the 12 ecological districts of Sinai gave the equation: log S = 1.0309+0.3 log A
The value of z=0.3 is higher than 0.222—the measured overall value for the continents and higher than the values for the Sahara, California mainland, the British Isles, and the Netherlands. However, it is lower than the values for the Galápagos Archipelago and the California Islands.The number of species supported in districts characterized by fissured limestone, gravel plains, chalk, marl, sandstones, sands or fissured magmatic and metamorphic rocks is close to the regression of species on area, whereas large outcrops of smooth-faced rocks are relatively richer in total number of species as well as in stenotople species.It is suggested that the high gamma diversity of Sinai as compared with other parts of the world is primarily due to its environmental heterogeneity. Sinai being a meeting place of three phytogeographical regions and to past climatic changes. The effect of smooth-faced rock outcrops as conducive to providing refugia must also be taken into account.This work is based on a comprehensive study of the vegetation of Sinai directed by Prof. G. Orshan, with the collaboration of Dr. A. Shmida, the present author and the late Prof. N.H. Tadmor and Dr. G. Halevy. 相似文献
7.
J. M. Melzer M. A. O'Connell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,83(3):337-344
Summary Asymmetric somatic hybrids were recovered following fusion of tomato leaf mesophyll protoplasts with irradiated protoplasts isolated from Lycopersicon pennellii suspension cells. The asymmetry was determined by scoring the regenerants at between 20 and 24 loci using isozymes and restriction fragment length polymorphisms. In addition, three quantitative traits, fruit size, leaf shape, and stigma exsertion, were measured in the regenerants. The recovery of asymmetric somatic hybrids was as high as 50% of the regenerants, and there was no requirement for the transfer of a selectable marker gene from the irradiated partner. The amount of nuclear DNA transferred from the irradiated protoplast fusion partner was found to be inversely proportional to the radiation dose. It was possible to recover tomato asymmetric somatic hybrids which were self-fertile and contained limited amounts of genetic information from L. pennelli. 相似文献
8.
《Bioorganic & medicinal chemistry letters》2014,24(24):5805-5813
The design and synthesis of a novel series of potent gamma secretase modulators is described. Exploration of various spacer groups between the triazole ring and the aromatic appendix in 2 has led to anilinotriazole 28, which combined high in vitro and in vivo potency with an acceptable drug-like profile. 相似文献
9.
《Reports of Practical Oncology and Radiotherapy》2020,25(1):6-12
AimThe aim of this study was to determine the Inflection Points (IPs) of flattening filter free (FFF) CyberKnife dose profiles for cone-based streotactic radiotherapy. In addition, dosimetric field sizes were determined.BackgroundThe increased need for treatment in the early stages of cancer necessitated the treatment of smaller tumors. However, efforts in that direction required the modeling accuracy of the beam. Removal of the flattening filter (FF) from the path of x-ray beam has provided the solution to those efforts, but required a different normalization approach for the beam to ensure the delivery of the dose accurately. As a solution, researchers proposed a normalization factor based on IPs.Materials and methodsMeasurements using microDiamond (PTW 60019), Diode SRS (PTW 60018) and Monte Carlo (MC) calculations of dose profiles were completed at SAD 80 cm and 5 cm depth for 15–60 mm cones. Performance analysis of detectors with respect to MC calculation was carried out. Gamma evaluation method was used to determine achievable acceptability criteria for FFF CyberKnife beams.ResultsAcceptability within (3%–0.5 mm) was found to be anachievable criterion for all dose profile measurements of the cone beams used in this study. To determine the IP, the first and second derivatives of the dose profile were determined via the cubic spline interpolation technique.ConclusionDerivatives of the interpolated profiles showed that locations of IPs and 50% isodose points coincide. 相似文献
10.
《Microbes and infection / Institut Pasteur》2020,22(8):294-302
Exposure to antimicrobials leading to microbiota dysbiosis has been found to be an independent risk factor for extensively drug-resistant Pseudomonas aeruginosa acquisition. Microbiota dysbiosis may induce imbalanced immune responses and can affect disease susceptibility. However, the potential role of commensal microbiota in bacterial pneumonia is poorly defined. The aim of this study was to investigate the mechanistic basis for the defective host defenses against P. aeruginosa pneumonia induced by antibiotic pretreatment perturbing microbiota. We found that antibiotic pretreatment significantly perturbed the composition of intestinal microbiota. The microbiota dysbiosis impaired host defenses against P. aeruginosa pneumonia, as reflected by the increased bacterial burden and dissemination, compromised local inflammatory responses and shortened survival time in microbiota-depleted mice compared with controls. This impairment correlated with a defective γδ T17 cell and downstream neutrophil responses. Anti-TCRγδ-treated mice had changes similar to those in the microbiota-depleted mice. Overall, our results suggest the importance of microbiota in supporting the host defense against pneumonia, define a crucial role for the γδ T cell-neutrophil axis in the potential mechanism, and delineate the deleterious effects of antibiotic treatment on antibacterial defenses. 相似文献