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91.
<正> 单葡萄糖甘油二酯(MGDG)和双葡萄糖甘油二酯(DGDG)是莱氏衣原体膜上主要的极性脂。糖脂的生理功能过去很少研究,至今仍不清楚。近年来实验结果表明,MGDG在膜上容易形成六角形Ⅱ结构,而DGDG则形成脂双层结构。六角形Ⅱ结构的出现与生物膜的生理功能的关系是当前瞩目的研究内容。本文首次研究了外源脂肪酸和胆固酵对莱氏衣原体AIH089菌株膜上糖脂含量的影响。 相似文献
92.
Swelling and Ca2+-activated Anion Conductances in C127 Epithelial Cells Expressing WT and ΔF508-CFTR
CFTR is a chloride channel that is required for fluid secretion and salt absorption in many exocrine epithelia. Mutations
in CFTR cause cystic fibrosis. CFTR expression influences some ion channels, but the range of channels influenced, the mechanism
of the interaction and the significance for cystic fibrosis are not known. Possible interactions between CFTR and other ion
channels were studied in C127 mouse mammary epithelial cell lines stably transfected with CFTR, ΔF508-CFTR, or vector. Cell
lines were compared quantitatively using an 125I efflux assay and qualitatively using whole-cell patch-clamp recording. As expected, 125I efflux was significantly increased by forskolin only in the CFTR line, and forskolin-stimulated whole-cell currents were
time- and voltage independent. All three lines responded to hypotonic challenge with large 125I efflux responses of equivalent magnitude, and whole-cell currents were outwardly rectified and inactivated at positive voltages.
Unexpectedly, basal 125I efflux was significantly smaller in the ΔF508-CFTR cell line than in either the CFTR or control cell lines (P < 0.0001), and the magnitude of the efflux response to ionomycin was largest in the vector cell line and smallest in the
cell line expressing ΔF508-CFTR (P < 0.01). Whole-cell responses to ionomycin had a linear instantaneous I-V relation and activated at depolarizing voltages. Forskolin responses showed simple summation with responses to ionomycin
or hypotonic challenge. Thus, we found no evidence for interactions between CFTR and the channels responsible for swelling-mediated
responses. Differences were found in basal and ionomycin-stimulated efflux, but these may arise from variations in the clonally
selected cell lines that are unrelated to CFTR expression.
Received: 15 November 1995/Revised: 16 February 1996 相似文献
93.
DNA Segments Sensitive to Single-Strand-Specific Nucleases Are Present in Chromatin of Mitotic Cells
It was observed before that DNAin situin chromatin of mitotic cells is more sensitive to denaturation than DNA in chromatin of interphase cells. DNA sensitivity to denaturation, in these studies, was analyzed by exposing cells to heat or acid and using acridine orange (AO), the metachromatic fluorochrome which can differentially stain double-stranded (ds) vs single-stranded (ss) nucleic acids, as a marker of the degree of DNA denaturation. However, without prior cell treatment with heat or acid no presence of single-stranded DNA in either mitotic or interphase cells was detected by this assay. In the present experiments we demonstrate that DNAin situin mitotic cells, without any prior treatment that can induce DNA denaturation, is sensitive to ss-specific S1 and mung bean nucleases. Incubation of permeabilized human T cell leukemic MOLT-4, promyelocytic HL-60, histiomonocytic lymphoma U937 cells, or normal PHA-stimulated lymphocytes with S1 or mung bean nucleases generated extensive DNA breakage in mitotic cells. DNA strand breaks were detected using fluorochrome-labeled triphosphonucleotides in the reaction catalyzed by exogenous terminal deoxynucleotidyl transferase. Under identical conditions of the cells’ exposure to ss-specific nucleases, DNA breakage in interphase cells was of an order of magnitude less extensive compared to mitotic cells. The data indicate that segments of DNA in mitotic chromosomes, in contrast to interphase cells, may be in a conformation which is sensitive to ss nucleases. This may be a reflection of the differences in the torsional stress of DNA loops between interphase and mitotic chromatin. Namely, greater stress in mitotic loops may lead to formation of the hairpin-loop structures by inverted repeats; such structures are sensitive to ss nucleases. The present method of detection of such segments appears to be more sensitive than the use of AO. The identification of mitotic cells based on sensitivity of their DNA to ss nucleases provides an additional method for their quantification by flow cytometry. 相似文献
94.
95.
以异源四倍体体细胞杂种为父本杂交培育三倍体柑桔植株的研究 总被引:23,自引:1,他引:22
以 3个柑桔原生质体融合而来的四倍体体细胞杂种为父本 ,与二倍体单胚性种柚子 (Citrusgrandis)以及单多胚混合型品种“华农本地早”桔 (C.reticulata)有性杂交 ,授粉后 90 d,发现种子干瘪 ,大部分种子的胚败育。将干瘪种子在 MT附加 1mg/L GA3 或 50 0 mg/L麦芽浸出物的培养基中 ,经培养抢救 ,有 2 5.6%的种子萌发成苗或继续进行胚的生长 ,后者进一步诱导能形成丛芽 ,经试管嫁接或诱导生根形成完整植株。共获得 6个组合 73棵完整植株 ,染色体数检查表明 ,2 0株为三倍体 (2 n=3x=2 7) ,32株为二倍体 (2 n=2 x=18) ,8株为非整倍体 ,其它 13株还有待于进一步检查。 相似文献
96.
从嗜热蓝藻优雅粘囊藻(Myxosarcina concinna Printz.)中分离到具有放氧活性的藻胆体-类囊体膜复合物。它的吸收峰位于680、628、490、438和420 nm ,在低离子强度(0.1~0.4 m ol/L)磷酸缓冲液中的664 nm 荧光发射峰随离子强度的降低而升高,718 nm 荧光发射峰与此相反(77 。K,Ex= 580 nm )。当把游离的藻胆体和已解离去藻胆体的类囊体膜在蔗糖磷酸缓冲液中重组时,随时间延长(0~60 m in),718 nm 荧光发射峰逐渐升高,685 nm 荧光发射峰逐渐下降(77 。K,Ex = 580 nm ),表明藻胆体与类囊体之间的解离和结合对光能传递的影响 相似文献
97.
懒猴属的核糖体DNA变异及其种间分化关系 总被引:5,自引:2,他引:3
用15种限制性内切酶和人28S、18SrDNA探针构建了懒猴属各物种核糖体DNA重复单位的限制性内切酶图谱。在进化速率较高的非转录间隔区,在大、中、小懒猴中分别定位了23、24、24个酶切位点。大懒猴与中懒猴有12个位点不同,与小懒猴有14个位点不同,而中、小懒猴间则只有一个位点的差异。经过计算,大懒猴与中懒猴的遗传距离值为12.65%,与小懒猴的差异为14.24%,中、小懒猴间的差异则仅为0.7 相似文献
98.
云南姬鼠的蛋白多态性及其遗传分化关系 总被引:3,自引:0,他引:3
本文采用蛋白电泳技术对来源于云南省若干地区的姬鼠属(Apodemus)的3种姬鼠──高山姬鼠(A.chevrieri)8只,中华姬鼠(A.draco)3只和大耳姬鼠(A.latronum)1只,以及作为外群的同科的绒鼠属的大绒鼠(Hapalomysdelalori)3只进行了分析。共检测遗传座位27个,发现21个座位存在多态性。根据蛋白多态的数据对研究对象进行遗传分化关系的探讨,用系统分析软件PHYLIP计算它们之间的分化关系,得到了一棵无根系统树。结果表明,作为外群的大绒鼠明显不同于其它3种姬鼠而聚在最外面。8只高山姬鼠个体汇聚成独立的一支,中华姬鼠的3个个体也聚成一支,但大耳姬鼠却聚在中华姬鼠一支中,因此我们认为大耳姬鼠同中华姬鼠的分化时间可能比较晚近。 相似文献
99.
生物复苏——大绝灭后生物演化历史的第一幕 总被引:12,自引:1,他引:11
生命史是一部生物界短期,快速剧变与长期,慢速稳定相互交替的历史。大绝灭(即集群绝灭)事件反映了全球环境的大突变,点断了地质历史中的生命记录及其发展历程,预示着生物界的演化出现了最有意义的飞跃,近年来尝试研究大绝灭后全球生物界的残存-复苏及其基本型式,并探索复苏的控制因素,标志着地质科学中一个重心的转移(即从大绝灭转向其后的生物残存与复苏的研究)。生物复苏揭示了大绝灭后生物演化历史的第一幕,其研究的 相似文献
100.
The Yeast Bsd2-1 Mutation Influences Both the Requirement for Phosphatidylinositol Transfer Protein Function and Derepression of Phospholipid Biosynthetic Gene Expression in Yeast 总被引:1,自引:0,他引:1 下载免费PDF全文
S. Kagiwada B. G. Kearns T. P. McGee M. Fang K. Hosaka V. A. Bankaitis 《Genetics》1996,143(2):685-697