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1.
The 30-Base-Pair Deletion in Chinese Variants of the Epstein-Barr Virus LMP1 Gene Is Not the Major Effector of Functional Differences between Variant LMP1 Genes in Human Lymphocytes 总被引:7,自引:3,他引:4 下载免费PDF全文
Rowena J. Johnson Maria Stack Sheila A. Hazlewood Matthew Jones Colin G. Blackmore Li-Fu Hu Martin Rowe 《Journal of virology》1998,72(5):4038-4048
One group of sequence variants of Epstein-Barr virus is characterized by a 10-amino-acid deletion within the CTAR-2 functional domain of the latent membrane protein, LMP1. A role for this deletion in enhancing the tumorigenicity of the viral oncogene in rodent fibroblasts was recently demonstrated. We examined the effect of this deletion upon LMP1 function in four human lymphoid cell lines by using three natural variants of LMP1: the prototype B95.8 gene and the CAO and AG876 genes, both of which have codons 343 to 352 of the B95.8-LMP1 deleted. These experiments revealed that LMP1-mediated upregulation of CD40 and CD54 was markedly impaired (by 60 to 90%) with CAO-LMP1 compared with B95.8-LMP1. In contrast, the function of AG876-LMP1 was indistinguishable from that of B95.8-LMP1 in two lines and was only slightly impaired in the other two lines. Activation of NF-κB by CAO-LMP1 was not impaired in any of the lines; rather, activation of an NF-κB reporter by CAO-LMP1 was consistently about twofold greater than the activation with B95.8- or AG876-LMP1. Therefore, while the CAO-LMP1 is functionally distinct from the prototype B95.8-LMP1 in human lymphocytes, the 10-amino-acid deletion appears not to be directly responsible. This conclusion was confirmed by using a B95.8-LMP1 mutant with codons 343 to 352 deleted and chimerae of CAO- and B95.8-LMP1 in which the CTAR-2 domains of these genes were exchanged. Sequences outside the CTAR-2 domain were implicated in the distinct functional characteristics of CAO-LMP1 in human lymphoid cells. 相似文献
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Sheila Polakoff 《BMJ (Clinical research ed.)》1987,294(6578):1031-1032
6.
Isolation and expression of an anther-specific gene from tomato 总被引:31,自引:0,他引:31
David Twell Rod Wing Judy Yamaguchi Sheila McCormick 《Molecular & general genetics : MGG》1989,217(2-3):240-245
7.
Robert M. Levin Penelope A. Longhurst Sheila S. Levin Niels Haugaard Alan J. Wein 《Molecular and cellular biochemistry》1990,97(2):153-159
The urinary bladder depends on intracellular ATP for the support of a number of essential intracellular processes including contraction. The concentration of ATP is maintained constant primarily via the rapid transfer of a phosphate from creatine phosphate (CP) to ADP catalyzed by the enzyme creatine kinase (CK). Since muscular pathologies associated with diabetes are in part related to intracellular alterations in metabolism, we have characterized the CK activity in both skeletal muscle and urinary bladder from control and streptozotocin-diabetic rats.The following is a summary of the results: 1) Bladder tissue from control rats showed linear kinetics with a Vmax = 390 nmoles/mg protein/min, and a Km = 275 µM. 2) Urinary bladder tissue isolated from diabetic rats displayed biphasic kinetics with Vmax = 65 and 324 nmoles/mg protein/min, and Km's = 10 µM and 190 µM respectively. 3) Skeletal muscle isolated from control rats showed linear kinetics with an approximate Vmax of 800 nmoles/mg protein/min and a Km of 280 µM CP. 4) Homogenates of skeletal muscle from diabetic rats showed complex kinetics not separable into distict component forms. 5) The Km for ADP for both skeletal muscle and bladder was approximately 10 µM.These studies demonstrate that whereas bladders isolated from both control and diabetic rats possess a low-affinity isomer(s) of CK with similar maximum enzymatic activity, there is a high affinity isomer present within the urinary bladder muscle of diabetic rats that is not present in bladder tissue isolated from control rats. Skeletal muscle isolated from both diabetic and control rats exhibited a maximal activity 2 to 3 times higher than that of the bladder. 相似文献
8.
Mammary epithelial cells from virgin Balb/c mice were isolated by collagenase digestion and cultured within collagen gels in serum-free basal medium containing insulin (10 micrograms/ml). Previous work has shown that linoleate or its metabolite, prostaglandin E2 (PGE2), stimulate the growth of these cells only in the presence of a growth stimulant such as epidermal growth factor (EGF). Since PGE2 can stimulate cyclic AMP (cAMP) production, the role of cAMP in linoleate and EGF-stimulated growth was examined. The cAMP phosphodiesterase inhibitor, IBMX (0.1 mM), was found to augment growth when cells were cultured in the presence of both EGF and linoleate or PGE2, but not either factor alone. These results indicated that EGF does not stimulate proliferation via cyclic AMP mediated events but could synergize with cAMP events if cAMP levels were elevated by PGE2. When assayed in cells plated on top of collagen-coated culture dishes, cellular cyclic AMP levels were stimulated by PGE2, but only marginally by EGF. Although the stimulation of endogenous cAMP by PGE2 and IBMX was insufficient to stimulate growth in the absence of EGF, exogenous dibutyryl-cAMP (greater than 100 micrograms/ml) was able to do so showing that a sustained, and high level of cAMP (greater than 100 micrograms/ml) could stimulate growth in insulin-containing basal medium. EGF was capable of enhancing the cellular sensitivity to dibutyryl-cAMP but the converse was not observed. cAMP stimulation of growth was dependent upon a superphysiological concentration of insulin (10 micrograms/ml) or a physiological concentration of somatomedin-C. These results indicate that the proliferation of mouse mammary epithelial cells can be stimulated separately or in synergism by cAMP-dependent or -independent events. 相似文献
9.
Sallie W. Chisholm Sheila L. Frankel Ralf Goericke Robert J. Olson Brian Palenik John B. Waterbury Lisa West-Johnsrud Erik R. Zettler 《Archives of microbiology》1992,157(3):297-300
Several years ago, prochlorophyte picoplankton were discovered in the N. Atlantic. They have since been found to be abundant within the euphotic zone of the world's tropical and temperate oceans. The cells are extremely small, lack phycobiliproteins, and contain divinyl chlorophyll a and b as their primary photosynthetic pigments. Phylogenies constructed from DNA sequence data indicate that these cells are more closely related to a cluster of marine cyanobacteria than to their prochlorophyte relatives Prochlorothrix and Prochloron. Several strains of this organism have recently been brought into culture, and herewith are given the name Prochlorococcus marinus. 相似文献
10.
Efficient selection intensity in early generation index selection in groundnut (Arachis hypogaea L.)
A. Bandyopadhyay V. Arunachalam K. Venkaiah 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,71(2):300-304
Summary The F2 potential of single and three-way crosses was evaluated using a set of physiological and yield components. Results were based on an index of selection using (a) only yield components and (b) both physiological and yield components. The indices were constructed using the percentage improvement of F2 over the better parent of the corresponding F1 cross for every character. The performance of F2 plants assessed by the expected value of the regression index was ranked in descending order to provide a ranked F2 distribution (FRD). The FRD was divided into four equal parts, T25 (top 25%), T50 (26–50%), T75 (51–75%) and T100 (76–100%). F3 families derived from F2 plants in T25 were found to provide a higher frequency of selections for pod number than T50, T75 and T100. The frequency of selections was higher in three-way than single crosses. Selection index based on physiological and yield components was more efficient in trapping F2 plants providing selections in F3 than the index based on yield components only. The results brought out the importance of bunch x bunch crosses as a complement to the usually advocated bunch x runner ones. 相似文献