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181.
Translational control of programmed cell death: eukaryotic translation initiation factor 4E blocks apoptosis in growth-factor-restricted fibroblasts with physiologically expressed or deregulated Myc. 总被引:13,自引:1,他引:12
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V A Polunovsky I B Rosenwald A T Tan J White L Chiang N Sonenberg P B Bitterman 《Molecular and cellular biology》1996,16(11):6573-6581
There is increasing evidence that cell cycle transit is potentially lethal, with survival depending on the activation of metabolic pathways which block apoptosis. However, the identities of those pathways coupling cell cycle transit to survival remain undefined. Here we show that the eukaryotic translation initiation factor 4E (eIF4E) can mediate both proliferative and survival signaling. Overexpression of eIF4E completely substituted for serum or individual growth factors in preserving the viability of established NIH 3T3 fibroblasts. An eIF4E mutant (Ser-53 changed to Ala) defective in mediating its growth-factor-regulated functions was also defective in its survival signaling. Survival signaling by enforced expression of eIF4E did not result from autocrine release of survival factors, nor did it lead to increased expression of the apoptosis antagonists Bcl-2 and Bcl-XL. In addition, the execution apparatus of the apoptotic response in eIF4E-overexpressing cells was found to be intact. Increased expression of eIF4E was sufficient to inhibit apoptosis in serum-restricted primary fibroblasts with enforced expression of Myc. In contrast, activation of Ha-Ras, which is required for eIF4E proliferative signaling, did not suppress Myc-induced apoptosis. These data suggest that the eIF4E-activated pathways leading to survival and cell cycle progression are distinct. This dual signaling of proliferation and survival might be the basis for the potency of eIF4E as an inducer of neoplastic transformation. 相似文献
182.
183.
Glycine substitutions in the triple-helical region of type VII collagen result in a spectrum of dystrophic epidermolysis bullosa phenotypes and patterns of inheritance. 总被引:5,自引:2,他引:3
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A. M. Christiano J. A. McGrath K. C. Tan J. Uitto 《American journal of human genetics》1996,58(4):671-681
The dystrophic forms of epidermolysis bullosa (DEB) are characterized by fragility of the skin and mucous membranes. DEB can be inherited in either an autosomal dominant or autosomal recessive pattern, and the spectrum of clinical severity is highly variable. The unifying diagnostic hallmark of DEB is abnormalities in the anchoring fibrils, which consist of type VII collagen, and, recently, mutations in the corresponding gene, COL7A1, have been disclosed in a number of families. In this study, we report six families with glycine substitution mutations in the triple-helical region of type VII collagen. Among the six families, two demonstrated a mild phenotype, and the inheritance of the mutation was consistent with the dominantly inherited form of DEB. In the four other families, the mutation was silent in the heterozygous state but, when present in the homozygous state, or combined with a second mutation, resulted in a recessively inherited DEB phenotype. Type VII collagen is, therefore, unique among the collagen genes, in that different glycine substitutions can be either silent in heterozygous individuals or result in a dominantly inherited DEB. Inspection of the locations of the glycine substitutions along the COL7A1 polypeptide suggests that the consequences of these mutations, in terms of phenotype and pattern of inheritance, are position independent. 相似文献
184.
Ribotyping to differentiate Fusobacterium necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme isolated from bovine ruminal contents and liver abscesses. 总被引:1,自引:1,他引:0
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O Okwumabua Z Tan J Staats R D Oberst M M Chengappa T G Nagaraja 《Applied microbiology》1996,62(2):469-472
Differences in biological activities (hemagglutination, hemolytic, leukotoxic, and virulence) and ribotypes between the two subspecies of Fusobacterium necrophorum of bovine ruminal and liver abscess origins were investigated. Hemagglutination activity was present in all hepatic, but only some ruminal, strains of Fusobacterium necrophorum subsp. necrophorum. Ruminal F. necrophorum subsp. necrophorum had low leukotoxin titers yet was virulent in mice. Fusobacterium necrophorum subsp. funduliforme of hepatic or ruminal origin had no hemagglutination activity, had low hemolytic and leukotoxic activities, and was less virulent to mice. For ribotyping, chromosomal DNAs of 10 F. necrophorum subsp. necrophorum and 11 F. necrophorum subsp. funduliforme isolates were digested with restriction endonucleases (EcoRI, EcoRV, SalI, PstI, and HaeIII) and examined by restriction fragment length polymorphisms after hybridizing with a digoxigenin-labeled cDNA probe transcribed from a mixture of 16 and 23S rRNAs from Escherichia coli. The most discriminating restriction endonuclease enzyme for ribotyping was EcoRI. The presence or absence of two distinct bands of 2.6 and 4.3 kb differentiated the two subspecies. Regardless of the origin, only F. necrophorum subsp. necrophorum, a virulent subspecies, had a ca. 2.6-kb band, whereas F. necrophorum subsp. funduliforme, a less virulent subspecies, had a ca. 4.3-kb band. Ribotyping appears to be a useful technique to genetically differentiate the two subspecies of F. necrophorum. 相似文献
185.
武汉东湖水生植被及其恢复途径探讨 总被引:4,自引:0,他引:4
1992~1993年对武汉东湖三个主要湖区(郭郑湖、汤林湖和牛巢湖)水生植被的调查表明,该湖区共有水生植物32种,优势种为大茨藻、狐尾藻、苦草和菱。金鱼藻呈不断扩大的趋势。植被类型可分为11个群丛,植被面积约为0.65km ̄2,总生物量为1236.39t(湿重),植被带状分布仅见于汤林湖北部和其他部分湖汊。汤林湖和牛巢湖水生植被正处于自然恢复演替阶段。 相似文献
186.
以人胃癌细胞BGC-823为模型,研究了毛喉萜(forskolin)对胃癌细胞中蛋白激酶C活性及其亚类基因表达的作用,同时也观察了毛喉萜对癌基因c-jun及抑癌基因p53表达的影响.结果表明,2×10~(-5)mol/L毛喉萜处理BGC-823细胞72h,细胞质、膜和细胞核PKC活性下降,PKC亚类β,γ基因表达被抑制,癌基因c-jun的表达也明显降低,而抑癌基因p53表达升高,上述变化可能是毛喉萜抑制胃癌细胞增殖等生理效应的重要分子事件。 相似文献
187.
188.
Abstract. In the Rhône delta, Juncus gerardi and Scirpus maritimus are often the dominant species in abandoned rice fields which are artificially flooded in early spring to improve forage production. Under these conditions they occur either in mixed communities, or form monospecific stands. Monitoring the vegetation dynamics in quadrats located in six abandoned rice fields artificially flooded from November to April confirmed the important role of grazing. In ungrazed plots, communities dominated by Scirpus maritimus mixed with Juncus gerardi developed fast. After 42 months of management Scirpus maritimus had established in nearly all quadrats and continued to expand, whereas Juncus gerardi had started to decline. In grazed plots Juncus gerardi alone dominated and continued to increase in cover up to the 42nd month. Scirpus maritimus established at low densities mainly in quadrats where Juncus gerardi was initially absent. Introduction of seeds of Scirpus maritimus in communities of Juncus gerardi under controlled conditions demonstrated the existence of the phenomenon of preemption. The increase in cover of Juncus gerardi suggests that the preemption of Juncus gerardi over Scirpus maritimus plays a more pronounced role in the field in the presence of grazing. 相似文献
189.
190.
The present study describes substance P-like immunoreactivity in the ciliary ganglia of monkey (Macaca fascicularis) and cat. About 60% of neurons in the monkey ciliary ganglion and 40% in the cat ciliary ganglion were substance P-like immunoreactive, ranging from faint to moderate staining. Substance P-like immunoreactivity was located in cell bodies, dendritic profiles and axons. In the monkey, substance P-like immunoreactive pericellular arborisations were associated with about 0.5%–3% of the ganglion cells, which were either negatively, faintly or moderately stained. An electron-microscopic study demonstrated the presence of either substance P-like immunoreactive positive or negative axon terminals synapsing or closely associated with positive dendritic profiles in both the monkey and cat ciliary ganglia. The results suggest that substance P plays an important role in the ciliary ganglion, perhaps as a modulator or transmitter. 相似文献