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David K. Grandy Richard Leduc Haripriya Makam Thomas Flanagan Emanuel J. Diliberto Jr. Olivier Civelli O. Humberto Viveros 《Cellular and molecular neurobiology》1992,12(2):185-192
1. A novel 1745-dalton pyroglutamyl peptide (BAM-1745)6 was recently isolated and characterized from bovine adrenal medulla chromaffin granules. Its amino acid sequence was found to be 93% identical to residues 580-593 of human chromogranin B (secretogranin I). 2. Based on this sequence a degenerate oligonucleotide probe was synthesized and used to identify a 2.4-kb bovine adrenal medulla chromogranin B cDNA. 3. The deduced polypeptide is 647 amino acids long and begins with a putative signal sequence of 20 residues as in the human, rat, and mouse proteins. Also conserved in the bovine protein is a tyrosine residue which may be sulfated, two N-terminal cysteines, and many paired basic amino acids which may serve as sites of posttranslational processing. The peptide BAM-1745 is flanked by paired basic amino acids and therefore is most likely a product of posttranslational processing. Bovine chromogranin B is 67, 58, and 58% identical to the human, rat, and mouse chromogranin B proteins, respectively. 4. The carboxyl terminus of bovine chromogranin B, including BAM-1745, was found to be the most conserved region of the polypeptide and may identify it as an important functional domain. 相似文献
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Visualization of poly(ADP-ribose) synthetase associated with polynucleosomes by immunoelectron microscopy 总被引:1,自引:0,他引:1
Antibodies showing a high specificity for poly(ADP ribose) synthetase have been purified. A fraction binding nonspecifically to histones present in antiserum and non-immune serum has been demonstrated by immunoblotting and separated by histone-Sepharose chromatography. The antibody without the nonspecific binding fraction was analyzed by Western blot with calf thymus protein extract and was found to react only with a band at 116 kDa. There was no reaction with purified topoisomerase I, this weak activity was copurified with poly(ADP-ribose) synthetase preparation. The specific IgG fraction has been used for the visualization of the interaction of poly(ADP-ribose) synthetase with chromatin by indirect gold-labelling. This immunomicroscopic study suggests that the synthetase is located in the inner part of polynucleosomes and would be associated preferentially with the core nucleosome. 相似文献
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An Electron Microscope Study of Intranuclear Inclusions in Mouse Liver and Hepatoma 总被引:8,自引:0,他引:8
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An electron microscope study of intranuclear inclusions which occur in giant cells in a transplantable mouse hepatoma and in enlarged liver cells in mice fed a diet containing bentonite demonstrates that these inclusions are formed by invaginations of the nuclear envelope, and corroborates a previous histochemical study which revealed that the contents of the inclusions are of cytoplasmic origin. In the hepatoma cells the intranuclear inclusions are abundant, small, and situated close to the border of the nucleus, and there are wide openings from the cytoplasm into the invaginations whose contents include lipid droplets, ergastoplasm, and structurally normal mitochondria. In the enlarged liver cells the inclusions are fewer in number, generally much larger than those in the hepatoma, hence they extend deeper into the nucleus, and the interior is continuous with the cytoplasm through only a small opening. Some normal ergastoplasm is present within the inclusions but all other constituents are abnormal. Both normal and degenerating mitochondria occur in the cytoplasm but only degenerating ones are found within the inclusions. Both types of inclusions arise in greatly enlarged cells in which an attempt is made to maintain the normal nuclear surface/nuclear volume ratio by the development of the invaginations of the nuclear envelope. 相似文献
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Fragmentation of bovine chromogranin A by plasma kallikrein 总被引:1,自引:0,他引:1
Chromogranin A has been reported to be processed in vivo by an as yet undefined proteinase(s) suggesting that it is a precursor of biologically active peptides such as pancreastatin. In this study, plasma kallikrein was used as a model proteinase to identify the cleavage sites exposed in bovine parathyroid chromogranin A. Purified bovine parathyroid chromogranin A was digested with human plasma kallikrein. The proteolytic fragments produced were isolated by HPLC and chemically characterized by amino acid composition and sequence analysis. The combined results indicate that the enzyme has preference for specific single Arg residues, cutting C-terminal to this amino acid, although certain pairs of basic sites were also cleaved. The characterized fragments were released in a selective manner from the whole molecule with rapid production of the fragments covering positions 1-247 and 352-358. 相似文献
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Nathalie Leduc Victor Alejandro Iglesias Roland Bilang Andreas Gisel Ingo Potrykus Christof Sautter 《Sexual plant reproduction》1994,7(2):135-143
Direct gene transfer to floral meristems could contribute to cell-fate mapping, to the study of flower-specific genes and promoters, and to the production of transgenic gametes via the transformation of sporogenic tissues. Despite the wide potential of its applications, direct gene transfer to floral meristems has not been achieved so far because of the lack of suitable technology. We show in this paper that ballistic micro-targeting is the technique of choice for this purpose, and in this way, we were able to transfer genes efficiently into excised wheat immature spikes. Particle size was adjusted for optimal penetration into the L1 and L2 cell layers of the spikes with limited cell damage. Spikes at different developmental stages were shot either with a plasmid containing two genes involved in anthocyanin biosynthesis or with a plasmid bearing the uidA (-glucuronidase) gene. The transient expression of these marker genes was observed in the different developmental stages tested and in cells of both the L1 and the L2 layers. The transient expression of the uidA gene was significantly increased when the sucrose concentration in the culture medium was increased from 0.06 to 0.52 M. At the highest concentration, 100% of the targeted spikes expressed the uidA gene, with an average of 69 blue cells per spike. Twelve days after microtargeting, multicellular sectors showing transgene expression and containing up to 17 cells were found in 85% of the shot immature inflorescences. This indicated that targeted cells survived particle bombardment. Sectors were found in primordia of both vegetative and reproductive organs. 相似文献
9.
目的 治疗艾滋病最大的障碍在于无法根除人类免疫缺陷病毒(HIV)潜伏于人体细胞所形成的病毒存储库。构建描述病毒存储库建立分子机制的动力学模型需考虑生物体内的噪声环境和多重影响因素,本文通过一种全新的动力学结构分解方法将随机微分方程的确定性部分与随机性噪声分开,从而在仅需分析常微分方程不动点的情况下即可判断不同药物靶点的作用效果。方法 使用连续的随机微分方程构建了HIV转录过程的动力学模型,简化了描述系统所需方程的维度,增大了模型的可探索空间,在此基础上,通过计算得到的势能函数和概率分布函数直观表示病毒潜伏与激活的不同表达状态以及它们之间的关系。结果 定量分析了不同动力学参数对系统稳态和势函数的影响程度,分别得到了系统处于双稳态和单稳态时的参数范围,并将不同因素对动力系统分岔的影响程度与生物学实验结果对比,验证了本工作的理论基础。结论 本文突破了以往离散、随机的方法,可以通过常微分方程定量分析HIV转录调控的动力学机制,有利于推广到处理高维情况,进一步研究艾滋病在生物体内的发生发展,从而指导设计实验寻找临床上的治疗方案。 相似文献
10.
Sequential isolation of proteoglycan synthesis mutants by using herpes simplex virus as a selective agent: evidence for a proteoglycan-independent virus entry pathway. 总被引:14,自引:9,他引:5
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![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A novel mouse L-cell mutant cell line defective in the biosynthesis of glycosaminoglycans was isolated by selection for cells resistant to herpes simplex virus (HSV) infection. These cells, termed sog9, were derived from mutant parental gro2C cells, which are themselves defective in heparan sulfate biosynthesis and 90% resistant to HSV type 1 (HSV-1) infection compared with control L cells (S. Gruenheid, L. Gatzke, H. Meadows, and F. Tufaro, J. Virol. 67:93-100, 1993). In this report, we show that sog9 cells exhibit a 3-order-of-magnitude reduction in susceptibility to HSV-1 compared with control L cells. In steady-state labeling experiments, sog9 cells accumulated almost no [35S]sulfate-labeled or [6-3H]glucosamine-labeled glycosaminoglycans, suggesting that the initiation of glycosaminoglycan assembly was specifically reduced in these cells. Despite these defects, sog9 cells were fully susceptible to vesicular stomatitis virus (VSV) and permissive for both VSV and HSV replication, assembly, and egress. HSV plaques formed in the sog9 monolayers in proportion to the amount of input virus, suggesting the block to infection was in the virus entry pathway. More importantly, HSV-1 infection of sog9 cells was not significantly reduced by soluble heparan sulfate, indicating that infection was glycosaminoglycan independent. Infection was inhibited by soluble gD-1, however, which suggests that glycoprotein gD plays a role in the infection of this cell line. The block to sog9 cell infection by HSV-1 could be eliminated by adding soluble dextran sulfate to the inoculum, which may act by stabilizing the virus at the sog9 cell surface. Thus, sog9 cells provide direct genetic evidence for a proteoglycan-independent entry pathway for HSV-1, and results with these cells suggest that HSV-1 is a useful reagent for the direct selection of novel animal cell mutants defective in the synthesis of cell surface proteoglycans. 相似文献