共查询到20条相似文献，搜索用时 78 毫秒
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[目的]了解吉林省新育成BT型不育系开花习性,为提高杂交稻制种产量提供基础数据。[方法]以吉林最新育成的三系粳稻不育系为材料,田间观察不育系的开花历期、开花动态、柱头外露率和异交结实率等开花习性。[结果]6个不育系的开花习性可以分为2类,A1、A2和A3可以分为一组,即始花时间早,终花时间也较早,花期集中,开花持续时间只有3h;开花高峰集中在11：00～11：30,午前花率很高,平均为88.3%,最高达到了93.8%。其他3个不育系分为另一组,始花时间较晚,终花时间也晚,开花时间长,开花高峰晚,基本都集中在12：30～13：00,午前花率很低,平均在46.0%,最高为59.0%。不育系的异交结实率和柱头外露率、开颖时间呈极显著的正相关,相关系数为0.996和0.955。[结论]选育柱头外露率高、开颖时间长的不育系可以提高制种产量。 相似文献
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六千辛A是江苏省农科院1978年用BT型黎明A为母本,六千辛为父本杂交转育成的BT型粳稻不育系.不育性能好,异交结实率高 群体不育株率及不育度均达百分之百,不育性稳定.出茎好,颖花开角约30°左右,见花后第四天全株达开花高峰,前后有6～7天的集中开花日(单株开花高峰期),开花数为全株总开花数的80%左右.日开花高峰明显(中午12时前后),群体花时5个小时,每朵花时60～70分钟.由于群体花时、花势相对集中和个体花时较长,异交结实率高,一般为30%左右. 相似文献
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《辽宁农业科学》2021,(2)
为探明粳稻三系不育系品种间异交结实特性的差异,明确不育系育种目标,对6个粳稻不育系的天然异交率及开花动态、柱头外露率等开花习性进行了初步研究。结果表明:粳65A和辽180A异交结实较为突出,天然异交率分别为59.6%和44.6%;粳65A和180A的花时早,11:00开花率高,分别为72.6%和49.1%;粳65A柱头外露率最高为65.1%;辽180A开颖时间最长为121 min;不育系的天然异交率与11:00花率和柱头外露率呈显著正相关,提早花时、提高柱头外露率有利于增加不育系的异交结实率;不育系的柱头外露率与11:00花率呈显著正相关,在不育系选育过程中早花时与高柱头外露率可以同时改良。 相似文献
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广占63 - 4S与扬稻6号(9311)杂交配组,F1种子经60Co -γ辐射诱变,从F3中选不育株割蔸再生,通过自然气候条件和人工低温对育性的加压选择,经过6年12代的定向培育,于2007年育成具有不育起点温度低、株型理想、优质、配合力强的光温敏核不育系扬籼1S,2010年通过江苏省农作物品种审定委员会审定.对扬籼1S异交特性研究表明,见穗3～4d后进入盛花期,表现为开花集中,日开花高峰为08:30-10:30,午前花率达93.0％,开颖历期较长;柱头总外露率为79.7％,其中单边外露率为39.4％,双边外露率为40.3％;柱头活力当天达53.6％,但持续性不强.对赤霉素非常敏感,解除包颈的最佳用量为75～ 150g/hm2.扬籼1S与不同类型父本制种的异交结实潜力有差异. 相似文献
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Effects of cyclosporine A on T cell development and clonal deletion 总被引：29，自引：0，他引：29
Cyclosporine A (CsA) is an important immunosuppressive drug that is widely used in transplantation medicine. Many of its suppressive effects on T cells appear to be related to the inhibition of T cell receptor (TCR)-mediated activation events. Paradoxically, in certain situations CsA is responsible for the induction of a T cell-mediated autoimmunity. The effects of CsA on T cell development in the thymus were investigated to elucidate the physiologic events underlying this phenomenon. Two major effects were revealed: (i) CsA inhibits the development of mature single positive (CD4+8- or CD4-8+) TCR-alpha beta+ thymocytes without discernibly affecting CD4-8- TCR-gamma delta+ thymocytes and (ii) CsA interferes with the deletion of cells bearing self-reactive TCRs in the population of single positive thymocytes that do develop. This suggests a direct mechanism for CsA-induced autoimmunity and may have implications for the relative contribution of TCR-mediated signaling events in the development of the various T cell lineages. 相似文献
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Holmes N 《Science (New York, N.Y.)》2008,321(5889):646-647
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Stejneger L 《Science (New York, N.Y.)》1904,19(479):371-376
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A cell culture model for T lymphocyte clonal anergy 总被引：183，自引：0，他引：183
R H Schwartz 《Science (New York, N.Y.)》1990,248(4961):1349-1356
T lymphocytes respond to foreign antigens both by producing protein effector molecules known as lymphokines and by multiplying. Complete activation requires two signaling events, one through the antigen-specific receptor and one through the receptor for a costimulatory molecule. In the absence of the latter signal, the T cell makes only a partial response and, more importantly, enters an unresponsive state known as clonal anergy in which the T cell is incapable of producing its own growth hormone, interleukin-2, on restimulation. Our current understanding at the molecular level of this modulatory process and its relevance to T cell tolerance are reviewed. 相似文献
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A thymic precursor to the NK T cell lineage 总被引：1，自引：0，他引：1
CD1d-restricted autoreactive natural killer (NK1.1+) T cells function as regulatory cells in various disease conditions. Using improved tetramer tracking methodology, we identified a NK1.1- thymic precursor and followed its differentiation and emigration to tissues by direct cell transfer and in situ cell labeling studies. A major lineage expansion occurred within the thymus after positive selection and before NK receptor expression. Surprisingly, cytokine analysis of the developmental intermediates between NK and NK+ stages showed a T helper cell TH2 to TH1 conversion, suggesting that the regulatory functions of NK T cells may be developmentally controlled. These findings characterize novel thymic and postthymic developmental pathways that expand autoreactive cells and differentiate them into regulatory cells. 相似文献
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Gamma interferon synthesis by human thymocytes and T lymphocytes inhibited by cyclosporin A 总被引：18，自引：0，他引：18
Cyclosporin A depresses the synthesis of gamma interferon by human thymocytes and T lymphocytes in vitro. This observation is of potential clinical significance because the long-term treatment of transplant patients with cyclosporin A, a widely used immunosuppressive agent, can give rise to B-cell lymphoma resulting from Epstein-Barr virus activation. 相似文献
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鸡胚成纤维细胞cDNA T7噬菌体表达文库的构建和鉴定 总被引：2，自引：0，他引：2
构建鸡胚成纤维细胞(CEF)T7噬菌体表达型cDNA文库,为筛选和研究CEF上病毒受体分子奠定基础。提取纯化CEF的mRNA,反转录合成双链cDNA,补平末端,连接EcoRⅠ/HindⅢ接头,双酶切,凝胶过滤层析除去小于400bp的cDNA片段,合成双链cDNA定向与T7噬菌体左右臂连接,体外包装后建成cDNA表达文库。测定文库大小、重组率,并以PCR鉴定cDNA插入片段的大小。结果表明,构建的cDNA文库滴度为2.2×107pfu/mL、扩增后滴度为3.5×1010pfu/mL,重组效率达98%、插入片段多在0.4～3kb之间,平均插入片段长约1.3kb。表明所建文库具有很高的质量,从而为筛选目的cDNA克隆奠定了基础。 相似文献