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61.
莱氏衣原体膜上Mg~(2+)-ATPase用DOC溶解后,经Sepharose-6B和DEAE-CelluloseDE-52离子交换柱,得到了部分纯化的Mg~(2+)ATPase,并将此ATPase与不同极性头部的磷脂和膜糖脂重组,研究了不同的极性头部的磷脂和膜糖脂对ATPase活性的影响。此酶的活性不依赖酸性磷脂,PG、DPG、大豆磷脂等明显抑制酶活性,中性磷脂DMPC、PE、PC则能增加酶活性,其中尤以非双层脂PE的作用最为明显。从莱氏衣原体膜上提取的糖脂(MGDG,DGDG)单独和ATPase重组时,酶活性增加并不明显,当MGDG和DGDG以等比例混合时,能大大地增加酶活性。这表明Mg~(2+)-ATPase的活性很大程度上与磷脂的表面电荷及磷脂的组成相关。 相似文献
62.
Abstract: Muscarinic receptor-mediated cyclic GMP formation and release of nitric oxide (NO) (or a precursor thereof) were compared in mouse neuroblastoma N1E-115 cells. [3 H]Cyclic GMP was assayed in cells prelabeled with [3 H]guanine. Release of NO upon the addition of muscarinic agonists to unlabeled neuroblastoma cells (NO donor cells) was quantitated indirectly by its ability to increase the [3 H]cyclic GMP level in labeled cells whose muscarinic receptors were inactivated by irreversible alkylation (NO detector cells). Carbachol increased NO release in a concentration-dependent manner, with half-maximal stimulation at 173 μ M (compared to 96 μ M for direct activation of cyclic GMP formation). The maximal effect of carbachol in stimulating release of NO when measured indirectly was lower than that in elevating [3 H]cyclic GMP directly in donor cells. Hemoglobin was more effective in blocking the actions of released NO than in attenuating direct stimulation of [3 H]cyclic GMP synthesis. There was a good correlation between the ability of a series of muscarinic agonists to release NO or to activate [3 H]cyclic GMP formation directly, and the potency of pirenzepine in inhibiting the two responses. Furthermore, there was a similar magnitude of desensitization of both responses by prolonged receptor activation or stimulation of protein kinase C. NO release was also regulated in relation to the cellular growth phase. A model is proposed in which a fraction of NO generated upon receptor activation does not diffuse extracellularly and stimulates cyclic GMP synthesis within the same cell where it is formed (locally acting NO). The remainder of NO that is extruded extracellularly might travel to neighboring cells (neurotransmitter NO) or might be taken back into the cells of origin (homing NO). 相似文献
63.
川西峨眉晚白垩世夹关期河流沉积中的痕迹化石群落* 总被引:9,自引:1,他引:8
晚白垩世夹关组中的痕迹化石群落至少由12个痕迹属17个痕迹种组成,其中包括5个新痕迹种,即Cystichrtium cuwatitivum,Steinichnus laryus,Paradidymaulichnus emeiertsis,Monmorphichnus lineates和Rusophycus univalvis.这一化石群落主要是无脊椎动物的进食迹、觅食迹、爬迹、停息迹和居住迹,其中多数呈下浮痕和全浮痕保存,并形成于经常干旱的河流环境(大多出现在泛滥平原沉积中).该群落可识别出两个痕迹化石组合,即1) Scoyenia-Steinichnus-Rusophycus组合,它主要产自泛滥平原和漫滩环境;2)Skolithos-Arenicolites组合,它代表一种水道砂坝或曲流砂坝环境. 相似文献
64.
Recombinant human kidney epithelial 293 cells were cultivated as aggregates in suspension. The concentration calcium ion, in the range of 100 muM to 1mM, affected the rate of aggregate formation. During the course of cultivation the size distribution of aggregates shifted and the fraction of larger aggregates increased. This effect was more profound in cultures with a high calcium concentration. Scanning and transmission microscopic examination of the aggregates revealed that cell packing was greater in the high calcium cultures and that ultrastructural integrity was retained in aggregates from both low and high calcium cultures. Confocal microscopy was applied to examine the viability of cells in the interior of the aggregates. High viability was observed in the aggregates obtained from exponentially growing cultures. Aggregates from the high calcium culture in the stationary phase exhibited lower viability in the interior. With its ease of retention in a perfusion bioreactor, aggregate cultures offer an alternative choice for large-scale operation. (c) 1993 John Wiley & Sons, Inc. 相似文献
65.
中国优质水果资源的分布与适宜生态环境 总被引:3,自引:0,他引:3
根据农业部在80年代两次组织评选出的全国189个优质水果产地的生态环境资料,用微型电子计算机系统建立数据库,统计分析柑桔、苹果和梨优质产品的构成比例、产区分布地域及其适宜的环境指标和主栽品种的生态适应性,为果树良种区域化栽培与选育提供依据。 相似文献
66.
67.
Y. P. Cruz R. S. Treichel E. Harsay K. D. Chi 《In vitro cellular & developmental biology. Animal》1993,29(8):671-675
Summary Immunosurgery is a useful technique for the isolation of inner cell masses from murine blastocysts. Conventionally, rabbit
antisera made ad hoc against murine splenic or fetal cells or fibroblasts have been used as antibody sources. We investigated
the feasibility of using commercially available rabbit antiserum to murine erythrocytes (anti-RBC) and compared it with rabbit
antiserum generated ad hoc to murine L-cells (anti-L-cell). Our results indicate that anti-RBC is at least as effective as
anti-L-cell serum for the immunosurgical isolation of inner cell masses, which became either miniblastocysts (later forming
outgrowths) or embryoid bodies (undergoing ectoderm-endodermlike differentiation within 48 h). Because anti-RBC is commercially
available, the technical modification described herein increases the accessibility of the immunosurgical protocol for the
isolation of murine inner cell masses. 相似文献
68.
Wang Zunxin Wang Xianyu Liu Siqin Yang Ying Li Yang Chen Siyuan Wang Guangpeng Zhang Xincheng Ye Yuxiu Hu Laibao Zhou Qing Wang Feibing Chen Xinhong 《Journal of Plant Growth Regulation》2023,42(1):294-303
Journal of Plant Growth Regulation - Zinc is an important micronutrient for the growth and development of human body and plants. Proper use of nitrogen fertilizer and foliar application of Zn have... 相似文献
69.
70.
相关遗传力抽样方差的估计 总被引:1,自引:0,他引:1
本文给出了单因子组和系统模型下有关相关传力及相关环境力抽样方差的估计方法。有关该参数在育种中的潜在应用其它与遗传相关之产间的相互关系也给予了一定的讨论。概括地来讲,相关遗传力具有遗传力和遗传相关的双重特征。遗传力是相关遗传力的一个特例而相关遗传力则是遗传力概念本身的扩展。用相关遗传力来表达性状间的相关遗传变异要比通常所用的遗传相关更准确一些。 相似文献