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991.
1992年3月至11月,我们在海南和长沙两地,先后使用38种化学调控剂,对水稻两用不育系,三系不育系及普通核不育系进行了喷施和注射试验,筛选出7种较为有效的调控剂,代号为CR1—CR7,其中CR5和CR7表现较为突出。这些调控剂对两用不育系和三系不育系均表现出一定程度的恢复效应,且CR1和CR2还能在可育条件下提高培矮64S的结实率,但所有调控剂对普通核不育系均无恢复作用。 相似文献
992.
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
993.
本文利用PCR技术,对人肿瘤坏死因子α(hTNFα)基因进行了改造,并将其与人白细胞介素-6(hIL-6)成熟肽编码区cDNA进行融合,构建了5′IL-6-TNF△融合蛋白的表达质粒pBVIL6-TNFA△。DNA序列分析证明,PCR扩增片段核苷酸序列与引物设计序列及相应的cDNA序列完全一致;重组子用限制性内切酶酶切鉴定,含有正确的IL6-TNF△融合cDNA片段;表达产物经SDS-聚丙烯酰胺凝胶电泳,分子量约为37kD,与预计的相符合;生物学活性分析初步表明,该融合蛋白具有抗肿瘤活性。 相似文献
994.
用共振拉曼和紫外-可见吸收光谱研究了水溶金属卟啉4-N-乙酸乙酯基-吡啶基铜卟啉和镍卟啉[简称Cu(NEAE)和Ni(NEAE)]及4-N-乙腈基-吡啶基铜卟啉[简称Cu(NACN)]与小牛胸腺DNA的相互作用。分析表明Cu(NEAE)、Ni(NEAE)和Cu(NACN)分别以外部键联、部分插入和沟槽方式与DNA作用;卟啉插入DNA时吡啶基团向卟啉环平面转动但不可能转成与之共面;而以非插入方式作用时吡啶基团会向垂直于或者平行于卟啉环平面转动。吡啶取代基的大小和空间位阻是影响相互作用方式的关键因素之一。 相似文献
995.
采用核酸分子杂交Southern印迹法,以32P标记的HBVDNA为探针,检测HBsAg阳性母亲引产的40例胎儿的肝、肾组织。结果有2例胎肝和1例胎肾细胞DNA出现大于3.2kb的杂交带,表明HBVDNA已处于整合状态。胎肾细胞基因组中查出HBVDNA整合为首次报道。 相似文献
996.
Zhijian Li Robert L. Jarret Roy N. Pittman James W. Demski 《In vitro cellular & developmental biology. Plant》1994,30(4):187-191
Summary Thidiazuron (TDZ) was utilized to induce adventitious shoot formation from the hypocotyl region of cultured seed explants
of peanut (Arachis hypogaea L.). Excision of the radicle from seed explants was more stimulatory to shoot initiation than removal of the epicotyl alone.
Removal of both the radicle and the epicotyl from seeds resulted in a 37-fold increase in the frequency of shoot production
when compared to intact seeds. Half seed explants with epicotyl and radicle removed produced the greatest number of shoots
per explant. Explants from mature seeds were more responsive to TDZ than immature seed-derived explants. A 1-wk exposure to
10 μM TDZ was sufficient to stimulate the initiation of adventitious shoots that subsequently developed into plants. High frequency
of shoot initiation was readily induced in a variety of genotypes ofA. hypogaea and a wild peanut (A. glabrata). Plants regenerated from shoots induced by TDZ were phenotypically normal and fertile. 相似文献
997.
Y. Li M. M. Bhargava A. Joseph L. Jin E. M. Rosen I. D. Goldberg 《In vitro cellular & developmental biology. Animal》1994,30(2):105-110
Summary Using an automated cell analyzer system, the effect of hepatocyte growth factor/scatter factor (HGF/SF), epidermal growth
factor (EGF), basic fibroblast growth factor (bFGF), endothelial acidic fibroblast growth factor (a-FGF), platelet derived
growth factor (PDGF), and recombinant human insulinlike growth factor (IGF) on the motility and morphology of Madin-Darby
canine kidney (MDCK), rat hepatomas, C2, and H5–6 and murine mammary carcinoma (EMT-6) cells was investigated. Treatment of MDCK cells with HGF/SF, bFGF, EGF, and a-FGF resulted
in an increase in average cell velocity and in the fraction of moving cells. Cells treated with the PDGF and IGF did not show
significant alterations in velocity. MDCK cells treated with each growth factor were classified into groups of “fast” and
“slow” moving cells based on their average velocities, and the average morphologic features of the two groups were quantitated.
Fast-moving cells had larger average area, circularity, and flatness as compared to slow-moving cells. Factors that stimulated
cell movement also induced alterations in cell morphologic parameters including spreading, flatness, area, and circularity.
HGF/SF also scattered and stimulated motility of C2 and H5–6 hepatoma cells. In contrast to MDCK cells, there was no significant difference between the morphology of the fast moving
and slow moving C2 and H5–6 cells. These studies suggest that growth factor cytokines have specific effects on motility of normal and tumor cells. 相似文献
998.
Zhuang XC Sun YZ Cui J Zhu JM Jiang C Xiang QL Li CS 《Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology》1994,1(1):P61-P63
In the environment of microgravity, the disused atrophy of skeletal muscle, especially leg's muscle, would occur. The three purposes of this study were: 1. To observe the dynamic changes of disused atrophy of skeletal muscle under simulated weightlessness; 2. To approach the mechanism of disused atrophy of muscle; 3. To approach the countermeasures for reducing the degree of atrophy of muscle. 相似文献
999.
Wen-Hsiung Li 《Journal of molecular evolution》1993,36(1):96-99
Summary The current convention in estimating the number of substitutions per synonymous site (K
S
) and per nonsynonymous site (K
A
) between two protein-coding genes is to count each twofold degenerate site as one-third synonymous and two-thirds nonsynonymous
because one of the three possible changes at such a site is synonymous and the other two are nonsynonymous. This counting
rule can considerably overestimate theK
S
value because transitional mutations tend to occur more often than transversional mutations and because most transitional
mutations at twofold degenerate sites are synonymous. A new method that gives unbiased estimates is proposed. An application
of the new and the old method to 14 pairs of mouse and rat genes shows that the new method gives aK
S
value very close to the number of substitutions per fourfold degenerate site whereas the old method gives a value 30% higher.
Both methods give aK
A
value close to the number of substitutions per nondegenerate site. 相似文献
1000.
Lymphocytes protect against and are not required for reovirus-induced myocarditis. 总被引:11,自引:10,他引:1 下载免费PDF全文
Many studies suggest that host lymphocytes are damaging, rather than protective, in virally induced myocarditis. We have investigated the role of lymphocyte-based immunity in murine myocarditis by using a myocarditic reovirus (reovirus serotype 3 8B), nonmyocarditic reoviruses, adoptive transfer experiments, and mice with severe combined immunodeficiency (SCID mice). Prior to infection, passive transfer of monoclonal antibodies specific for 8B capsid proteins protected neonatal mice against 8B-induced myocarditis, indicating that humoral immunity can protect against myocarditis. Some monoclonal antibodies acted by blocking viral spread to and/or replication in the heart. Passive transfer of reovirus-immune, but not naive, spleen cells prior to infection protected neonatal mice from 8B-induced myocarditis. Depletion of either CD4 or CD8 T cells resulted in increased viral titer in the heart but did not abrogate immune cell-mediated protection against myocardial injury. This shows that both CD4 and CD8 T cells can act independently to protect myocardial tissue from reovirus infection. In addition, reovirus 8B caused extensive myocarditis in SCID mice. This confirms a prior report (B. Sherry, F. J. Schoen, E. Wenske, and B. N. Fields, J. Virol. 63:4840-4849, 1989) that T cells are not required for reovirus-induced myocarditis and demonstrates for the first time that B cells are not required for reovirus-induced myocarditis. We used SCID mice and a panel of reoviruses to assess (i) the relationship between growth in the heart and myocardial damage and (ii) the possibility that nonmyocarditic reoviruses exhibit a myocarditic phenotype in the absence of functional lymphocytes. Growth in the heart was not the sole determinant of myocarditic potential in SCID mice. Although 8B induced myocarditis in SCID mice, no or minimal myocarditis was found in SCID mice infected with four reovirus strains previously shown (B. Sherry and B. N. Fields, J. Virol. 63:4850-4856, 1989) to be nonmyocarditic or poorly myocarditic in normal neonatal mice. We conclude that (i) humoral immunity and cellular immunity are protective against, and not required for, reovirus-induced myocarditis and (ii) the potential to induce cardiac damage is a property of the virus independent of lymphocyte-based immunity. 相似文献