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21.
22.
鹅掌楸雌配子体败育对生殖的影响 总被引:12,自引:0,他引:12
胚珠和雌配子体败育是限制鹅掌楸生殖成功的一个重要因素。中国东部和西部鹅掌楸种群在雌配子体发育的各阶段上的败育程度有差异,以西部种群的发育较好。西部分布区较合适的生境促进了胚囊的发育,一定温度和湿度的环境可以活化珠心细胞输送营养物质供给雌配子体发育,提高受精和结籽的能力 相似文献
23.
探讨了研制的具有谷胱甘肽过氧化物酶活力的含硒抗体酶(GPX-abzyme)对于受损心肌线粒体的保护作用,利用牛的心肌线粒体为实验材料,通过线粒体的膨胀度、脂质过氧化物含量、CCO活力变化及电镜观察等几个方面证明GPX-abzyme能抵抗XO/HX系统产生的自由基的损伤作用,ESR研究也表明GPX-abzyme能明显降低XO/HX损伤系统中的自由基含量。 相似文献
24.
木瓜蛋白酶PPAⅢ自水解作用 总被引:1,自引:0,他引:1
木瓜蛋白酶PPAⅢ自水解作用王秀艳,周慧,葛玉斌,李惟(吉林大学分子生物学系,长春130023)PPAⅢ、papain、pepsine、stembromelain等都属于以Cys-SH为活性中心的酶,同种分子之间存在着一种相互切割的趋势,称为酶自水解... 相似文献
25.
Laminin and Neuropeptide Y Are Increased by Synapsin Transfection in Cultured NG108-15 Neuroblastoma/Glioma Hybrid Cells 总被引:2,自引:0,他引:2
† Gabriel Fried Hui Quan Han ‡Björn Meister ‡Tomas Hökfelt Paul Greengard 《Journal of neurochemistry》1995,64(6):2674-2680
Abstract: We have investigated the presence and expression of laminin and neuropeptide Y (NPY) in several NG108-15 cell lines transfected with synapsin Ib, IIa, or IIb. The content of laminin, a basal membrane glycoprotein that promotes adhesion and induces neurite outgrowth and neuronal differentiation, was increased in all transfected cell lines examined. In cells that were chemically differentiated with prostaglandin E1 plus 3-isobutyl-1-methylxanthine, laminin levels were increased even further. The content of NPY, suggested to be a neurotransmitter/neuromodulator in peripheral sympathetic neurons as well as in central neurons, was also increased in all transfected cell lines examined. Immunohistochemical analysis combined with confocal laser microscopy showed that NPY staining was granular and very often enriched in neuritic varicosities. The distribution and the staining pattern of NPY were consistent with storage of NPY in large dense-cored vesicles. The results indicate that, in differentiated neurons, the synapsins increase the levels of a neuropeptide transmitter stored in large dense-cored vesicles and of an extracellular matrix protein associated with neuronal maturation. 相似文献
26.
Thermotolerance in cultures of Chlorella zofingiensis was induced by heat shock treatment at supraoptimal temperatures (40and
45 °C for 30 min). Thermotolerance was assayed by two methods: the survival of the cells at 70 °C and the growth of diluted
cultures at 35 and 45 °C. A culture without heat shock treatment was unable to grow at 45 °C. According to eletrophoretic
analyses, the synthesis of proteins of 95, 73, 60, 43 and 27 kDa was induced by heat shock treatment. The large molecular
weight proteins (95, 73, 60 and43 kDa) were present in non-heat treated cells, but the heat shock treatment increased their
quantity in cells. The synthesis of a low molecular weight protein (27 kDa) was induced by heat shock treatment. The induced
thermotolerance could be inhibited by the presence of an 80S ribosomal translation inhibitor, cycloheximide(CHI). The first
12 amino acid residues from the N-terminus of the27 kDa heat shock induced protein are Val-Glu-Trp-Try-Gly-Pro-Asn-Arg-Ala-Lys-Phe-Leu.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
27.
Human genes for glutathione S-transferases 总被引:11,自引:2,他引:9
The tissue distribution of different glutathione S-transferases (GST) is analysed by electrophoresis. The existence of GST"e" (erythrocyte), GST3, GST1, and GST2 is confirmed. GST"e" the fastest and most thermolabile of different GST analysed is observed only in erythrocyte cells. GST3 which migrates more slowly than GST"e" is present in all tissues and cells analysed, excepted for erythrocyte cells in which only GST"e" is observed. GST1 presents a polymorphism with four phenotypes, 1, 1/2, 2, and 0 controlled by three alleles 1, 2, and 0 (null). With the sample of 56 livers analysed the different frequencies obtained are 9%, 5%, 43%, 43% for the phenotypes 1, 1/2, 2, and 0 respectively and 0.074 (p), 0.279 (q), 0.647 (r) for the alleles, 1, 2, and 0 (null). GST2 presents variant patterns due probably, in the majority of cases, to post-synthetic modifications rather than allelic variation. Two new GST are described, GST4 and GST5. GST4 abundant in muscle tissue is a dimeric protein. GST4 forms with GST1 a heterodimeric band. GST5 is observed in brain homogenates. For the chromosome localization the results obtained by man (leucocytes)-mouse somatic cell hybrid analysis indicate that the gene for leucocytes GST is on chromosome 11. This gene is the structural GST3 gene. 相似文献
28.
Comparison of charge movement components in intact and cut twitch fibers of the frog. Effects of stretch and temperature 总被引:5,自引:2,他引:3 下载免费PDF全文
C S Hui 《The Journal of general physiology》1991,98(2):287-314
Charge movements were measured in frog intact fibers with the three-microelectrode technique and in cut fibers with the double Vaseline gap technique. At 13-14 degrees C, the ON segments of charge movement records from both preparations showed an early I beta component and a late I gamma hump component. When an intact fiber was cooled to 4-7 degrees C, the time-to-peak of I gamma (tp,gamma) was prolonged, but I gamma still appeared as a hump. Q-V plots from intact fibers at 4-7 degrees C were fitted with a sum of two Boltzmann distribution functions (method 1). The more steeply voltage-dependent component, identified with Q gamma, accounted for 32.1% (SEM 2.2%) of the total charge. This fraction was larger than the 22.6% (SEM 1.5%) obtained by separating the ON currents with a sum of two kinetic functions (method 2). The total charge in cut fibers stretched to a sarcomere length of 3.5 microns at 13-14 degrees C was separated into Q beta and Q gamma by methods 1 and 2. The fraction of Q gamma in the total charge was 51.3% (SEM 1.7%) and 53.7% (SEM 1.8%), respectively, suggesting that cut fibers have a larger proportion of Q gamma:Q beta than intact fibers. When cut fibers were stretched to a sarcomere length of 4 microns, the proportion of Q gamma:Q beta was unchanged. Between 4 and 13 degrees C, the Q10 of l/tp,gamma in intact fibers was 2.33 (SEM 0.33) and that of 1/tau beta was less than 1.44 (SEM 0.04), implying that the kinetics of I gamma has a steeper temperature dependence than the kinetics of I beta. When cut fibers were cooled from 14 to 6 degrees C, I gamma in the ON segment generally became too broad to be manifested as a hump. In a cut fiber in which I gamma was manifested as a hump, the Q10 of l/tp,gamma was 2.08 and that of l/tau beta was less than 1.47. Separating the Q-V plots from cut fibers at different temperatures by method 1 showed that the proportion of Q gamma:Q beta was unaffected by temperature change. The appearance of I gamma humps at low temperatures in intact fibers but generally not in cut fibers suggests an intrinsic difference between the two fiber preparations. 相似文献
29.
Increasing methylation of the headgroup in DPPE results in an increase of minimum area per molecule in highly compressed monolayers at the air-water interface. The shape of solid domains, as observed by epifluorescence microscopy, also exhibits marked changes upon increasing headgroup methylation. Branching domains are observed in DPPE and DP(Me)PE, whereas U-shaped or round domains are observed in DP(Me)2PE and DPPC under our experimental conditions. The domain shape is determined more by the headgroup methylatin than by the corresponding shift in critical temperatures, as shown by the study of PCs of different acyl chain moieties. In mixed lipid monolayers, PC (phosphatidylcholine) and PE (phosphatidylethanolamine) do not mix ideally, as indicated by the non-linear variation of the average area per molecule with composition, and by distinct domain shapes in LE/LC (liquid expanded/liquid condensed) coexisting phases representing PE-enriched or PC-enriched domains in those mixed monolayers. 相似文献