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排序方式: 共有718条查询结果,搜索用时 15 毫秒
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2.
S Ghanshani M Pak J D McPherson M Strong B Dethlefs J J Wasmuth L Salkoff G A Gutman K G Chandy 《Genomics》1992,12(2):190-196
3.
Vidadi M. Yusibov Pak Chun II Viacheslav M. Andrianov Eleonora S. Piruzian 《Plant molecular biology》1991,17(4):825-836
The tumour-inducing T-DNA gene 4 (T-cyt gene) of the nopaline Ti plasmid pTiC58 was cloned and introduced into tobacco cells by leaf disc transformation using Agrobacterium plasmid vectors. Tobacco shoots exposed to elevated cytokinin levels were unable to develop roots and lacked apical dominance. Using exogenously applied phytohormone manipulations we were able to regenerate morphologically normal transgenic tobacco plants which differed in endogenous cytokinin levels from normal untransformed plants. Although T-cyt gene mRNA levels, as revealed by dot-blot hybridization data, in these rooting plants were only about half those in primary transformed shoots the total amount of cytokinins was much lower than in crown gall tissue or cytokinin-type transformed shoots as reported by others. Nevertheless the cytokinin content in T-cyt plants was about 3 times greater than in control tobacco plants.Elevated cytokinin levels have been shown to change the expression of several plant genes, including some nuclear genes encoding chloroplast proteins. Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants. Data obtained suggest that T-cyt transgenic plants are a good model for studying plant gene activity in different parts of the plant under endogenous cytokinin stress. 相似文献
4.
L V Krasheninnikova G V Rassadina S N Kirsanova L M Khromova V M Iusibov I r Pak Chun V M Andrianov E S Piruzian 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1991,(11):17-20
The genetic constructions based on integrative vector pGV3850 were used to introduce bacterial genes xyl and T-cyt into potato cells. The transformation was carried out using the leaf-disc method with modifications. A special system for obtaining regenerants from explants of potato in vitro plants or calli has been designed that permitted the selection of transgenic shoots. The presence of the genes in potato genome has been proved by testing the NPTII and glucoisomerase activities. The transgenic plants expressing T-cyt gene differed from the wild type in sharp decrease of the apical dominance. 相似文献
5.
Electrophysiological investigations were carried out on several independently isolated mutants of the ninaE gene, which encodes opsin in R1-6 photoreceptors, and a mutant of the ninaD gene, which is probably important in the formation of the rhodopsin chromophore. In these mutants, the rhodopsin content in R1-6 photoreceptors is reduced by 10(2)-10(6)-fold. Light-induced bumps recorded from even the most severely affected mutants are physiologically normal. Moreover, a detailed noise analysis shows that photoreceptor responses of both a ninaE mutant and a ninaD mutant follow the adapting bump model. Since any extensive rhodopsin-rhodopsin interactions are not likely in these mutants, the above results suggest that such interactions are not needed for the generation and adaptation of light-induced bumps. Mutant bumps are strikingly larger in amplitude than wild-type bumps. This difference is observed both in ninaD and ninaE mutants, which suggests that it is due to severe depletion of rhodopsin content, rather than to any specific alterations in the opsin protein. Lowering or buffering the intracellular calcium concentration by EGTA injection mimics the effects of the mutations on the bump amplitude, but, unlike the mutations, it also affects the latency and kinetics of light responses. 相似文献
6.
J Yoon R D Shortridge B T Bloomquist S Schneuwly M H Perdew W L Pak 《The Journal of biological chemistry》1989,264(31):18536-18543
7.
M. Rita I. Young Gayle McCloskey Mark A. Wright Annette Schmidt Pak 《Cancer immunology, immunotherapy : CII》1994,38(1):9-15
By secreting granulocyte/macrophage colonystimulating factor (GM-CSF), metastatic Lewis lung carcinoma (LLC-LN7) tumors induce the appearance of myelopoiesis-associated immune-suppressor cells that resemble granulocytic-macrophage (GM) progenitor cells. The presence of these GM-suppressor cells in mice bearing LLC-LN7 tumors was associated with a reduced capacity of splenic T cells to proliferate in response to interleukin-2 (IL-2). Administration of low doses of 100 U interferon (IFN) plus 10 U tumor necrosis factor (TNF) to the tumor bearers, a combination treatment that we previously showed to diminish the presence of GM-suppressor cells synergistically, restored proliferative responsiveness of the splenic T cells to IL-2. These LLC-LN7-bearing mice were also examined for whether cells that phenotypically resemble GM-progenitor cells (ER-MP12+ cells) infiltrate the tumor mass. ER-MP12+ cells composed approximately 10% of the cells isolated from dissociated tumors of mice that had been treated with placebo or with either IFN or TNF alone, but IFN/TNF therapy markedly reduced the number of tumor-infiltrating ER-MP12+ suppressor cells. The IFN/TNF treatment to eliminate GM-suppressor cells and restore T cell responsiveness to IL-2 was next coupled with low dose IL-2 therapy (100 U twice daily). Addition of IL-2 to the treatment regimen did not significantly influence the effectiveness of the IFN/TNF treatment in eliminating GM-suppressor cells from the LLC-LN7 tumor mass. However, inclusion of IL-2 with the IFN/TNF treatment regimen enhanced the CD8+, but not the CD4+, cell content within the tumor, and diminished the number of metastatic lung nodules within the mice. When these tumors were excised, dissociated, and bulk-cultured with a low dose of IL-2, an increased level of cytotoxic T lymphocyte (CTL) activity was generated in the TIL cultures from mice that had received IFN/TNF plus IL-2 treatments. A lesser but detectable level of CTL activity was generated in TIL cultures from mice that were treated with only IFN/TNF, while no CTL activity was generated in tumor cultures from mice receiving only placebo or low-dose IL-2. These results suggest the effectiveness of IFN plus TNF therapy in restoring IL-2 responsiveness in mice bearing GM-suppressor cell-inducing tumors and at enhancing both the intratumoral CD8+ cell content and the generation of CTL activity in bulk cultures of these tumors.This study was supported by the Medical Research Service of the Department of Veterans Affairs, by grants CA-45080 and CA-48080 from the National Institutes of Health, and by the American Cancer Society, Illinois 相似文献
8.
Astrocytes are important in regulating the microencironment of neurons both by catabolic and synthetic pathways. The glutamine synthetase (GS) activity observed in astrocytes affects neurons by removing toxic substances, NH3 and glutamate; and by providing an important neuronal substrate, glutamine. This glutamate cycle might play a critical role during periods of hypoxia and ischemia, when an increase in extracellular excitatory amino acids is observed. It was previously shown in our laboratory that fructose-1,6-bisphosphate (FBP) protected cortical astrocyte cultures from hypoxic insult and reduced ATP loss following a prolonged (18–30 hrs) hypoxia. In the present study we established the effects of FBP on the level of glutamate uptake and GS activity under normoxic and hypoxic conditions. Under normoxic conditions, [U-14C]glutamate uptake and glutamine production were independent of FBP treatment; whereas under hypoxic conditions, the initial increase in glutamate uptake and an overall increase in glutamine production in astrocytes were FBP-dependent. Glutamine synthetase activity was dependent on FBP added during the 22 hours of either normoxic- or hypoxic-treatment, hence significant increases in activity were observed due to FBP regardless of the oxygen/ATP levels in situ. These studies suggest that activation of GS by FBP may provide astrocytic protection against hypoxic injury. 相似文献
9.
10.
Sakaba Tomoka Soejima Akiko Fujii Shinji Ikeda Hajime Iwasaki Takaya Saito Hiroaki Suyama Yoshihisa Matsuo Ayumi Kozhevnikov Andrey E. Kozhevnikova Zoya V. Wang Hongfeng Wang Siqi Pak Jae-Hong Fujii Noriyuki 《Journal of plant research》2023,136(4):437-452
Journal of Plant Research - A group of temperate grassland plant species termed the “Mansen elements” occurs in Japan and is widely distributed in the grasslands of continental East... 相似文献