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21.
在细叶黄芪叶肉原生质体发育早期,细胞器的变化较大。离体培养4h后,线粒体的嵴和基质物质开始增加。培养3—5天后,线粒体的数量增加5倍以上,此时可见大部分线粒体围绕细胞核分布。在培养24h后,高尔基体开始发育,它们主要分布在细胞质周边区域。多糖细胞化学染色表明,高尔基体内沉积着大量嗜银物质。培养1天后,粗面内质网开始发育。培养3天时,部分叶绿体边缘出现一些空隙结构。随着叶绿体内膜结构的消失,淀粉粒增大,叶绿体逐渐转变为造粉质体。 相似文献
22.
23.
本文报导了胰腺提取物中两种可被钙/钙调素依赖性蛋白激酶磷酸化的热稳定蛋白。SDS-PAGE测定其表观分子量分别为17.7kD和6kD。经钙/钙调素依赖性蛋白激酶磷酸化后,其最大磷酸参入量为8.8μmol/g蛋白。同时磷酸化作用导致17.7kD蛋白在SDS-PAGE中迁移率发生变化。本文还进一步分析了各种阳离子对磷酸化的影响,并对此两种蛋白可能具有的生理功能进行了初步探讨。 相似文献
24.
Differential regulation of vascular cell adhesion molecule 1 gene expression by specific NF-kappa B subunits in endothelial and epithelial cells. 总被引:21,自引:5,他引:16 下载免费PDF全文
H B Shu A B Agranoff E G Nabel K Leung C S Duckett A S Neish T Collins G J Nabel 《Molecular and cellular biology》1993,13(10):6283-6289
25.
本文报导五加科一新属,人参本属Chengiopanax Shang et J.Y.Huang,新组合2种,即华人参木Ch.fargesii(Franch.)Shang et J.Y.Hung及人参木Ch.sciadophylloides(Franch.et Sav.)Shang et J.Y.Huang。 相似文献
26.
The anatomy of the arthropod Squamacula clypeata Hou and Bergström, 1997 from the Lower Cambrian Chengjiang Lagersta¨tte is redescribed based on four newly excavated specimens. The new material was collected from localities recently discovered in the Kunming area, Yunnan Province, south-west China, and preserves remarkable details of the ventral morphology, revealed by preparation. Squamacula clypeata is dorsoventrally flattened and rounded in outline. The cephalon was covered by a wide, short shield, with a large doublure and a pair of uniramous antennae on the ventral side. The thorax consists of nine somites, each protected by a tergite and carrying at least one pair of biramous limbs. The pygidium is covered with a small rounded tergum. The endopod is segmented, equipped with short spines on the inner margin of the coxa and a claw-like structure distally, and the exopod flap-like, fringed with setae. The limbs in the pygidium are like those in the thorax in shape. Squamacula was most probably a nektobenthic predator. The spinose endopod could walk, grasp and grind. The large flap-like exopod was adapted for swimming and respiration. Its affinities lie with the Arachnomorpha, but the relationships with other known taxa remain ambiguous. 相似文献
27.
C-H. Shu W. K. Yang T-S. Huang 《Apoptosis : an international journal on programmed cell death》1996,1(2):141-146
Paclitaxel is a potential cancer chemotherapeutic agent for ovary, breast, and head and neck cancers; its effects on nasopharyngeal
carcinoma (NPC) have not been reported previously. This study investigated the cytotoxic mechanism of paclitaxel in two NPC
cell lines, NPC-TW01 and NPC-TW04. NPC cells treated with pacli-taxel showed convoluted nuclei, condensed chromatin and decreased
cellular and nuclear volume, and also exhibited genomic DNA degradation into multiple oligonucleosomal fragments, suggesting
that pacli-taxel induced apoptosis in these cells. The effects of paclitaxel on apoptosis-related proteins including Bcl-2,
Bax and CDC 2 were also detected. Although the levels of Bcl-2 and Bax were not changed in NPC cells following treatment with
5 nM-1 μM of paclitaxel, phosphorylation of Bcl-2 was significantly observed in the cells treated with 1 μM of paclitaxel
for 12 hours. In addition, cyclin B1-associated CDC 2 kinase was highly activated in the NPC cells exposed to paclitaxel even
at low (5 nM) concentration, and this result is associated with the finding that low concentration of paclitaxel is able to
induce apoptosis in NPC cells. 相似文献
28.
高维非自治系统的周期解 总被引:1,自引:0,他引:1
本文通过建立并利用齐次线性方程解的估计公式,获得了周期系统(1)的周期解的存在性、唯一性定理,对周期系统(2)给出了一个平稳振荡定理,最后给出了实例。 相似文献
29.
SCS1, a multicopy suppressor of hsp60-ts mutant alleles, does not encode a mitochondrially targeted protein. 总被引:2,自引:2,他引:0 下载免费PDF全文
We identified and isolated a Saccharomyces cerevisiae gene which, when overexpressed, suppressed the temperature-sensitive phenotype of cells expressing a mutant allele of the gene encoding the mitochondrial chaperonin, Hsp60. This gene, SCS1 (suppressor of chaperonin sixty-1), encodes a 757-amino-acid protein of as yet unknown function which, nonetheless, has human, rice, and Caenorhabditis elegans homologs with high degrees (ca. 60%) of amino acid sequence identity. SCS1 is not an essential gene, but SCS1-null strains do not grow above 37 degrees C and show some growth-related defects at 30 degrees C as well. This gene is expressed at both 30 and 38 degrees C, producing little or no differences in mRNA levels at these two temperatures. Overexpression of SCS1 could not complement an HSP60-null allele, indicating that suppression was not due to the bypassing of Hsp60 activity. Of 10 other hsp60-ts alleles tested, five could also be suppressed by SCS1 overexpression. There were no common mutant phenotypes of the strains expressing these alleles that give any clue as to why they were suppressible while others were not. An epitope (influenza virus hemagglutinin)-tagged form of SCS1 in single copy complemented an SCS1-null allele. The Scs1-hemagglutinin protein was found to be at comparable levels and in similar multiply modified forms in cells growing at both 30 and 38 degrees C. Surprisingly, when localized either by cell fractionation procedures or by immunocytochemistry, these proteins were found not in mitochondria but in the cytosol. The overexpression of SCS1 had significant effects on the cellular levels of mRNAs encoding the proteins Cpn10 and Mgel, two other mitochondrial protein cochaperones, but not on mRNAs encoding a number of other mitochondrial or cytosolic proteins analyzed. The implications of these findings are discussed. 相似文献
30.
The production of D-lactic acid by Lactobacillus delbrueckii (ATCC 9649) during fermentation was monitored on-line with a reagentless D-lactate dehydrogenase modified carbon paste electrode in a flow injection system integrated with a filtration sampling device. The time delay between sampling and detection was approximately 6 min. The use of an electropolymerized ortho-phenylenediamine membrane on the elctrode resulted in a very selective sensor response with acceptable stability and sensitivity. The D-lactate concentrations determined on-line agreed well with those determined by a standard method, suggesting that this sensor system is suitable for on-line monitoring of fermentation processes. (c) 1995 John Wiley & Sons, Inc. 相似文献