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| | An improved PEG method was used to induce fusion of Nicotiana rustica protoplast and IOA inactivated Lycium barbarum protoplast. The hetero-fusion frequency was found ca, 2%, Among 250 calli recovered, 5 were green, which were morphologically similar to callus of L. barbarum. Isozyme analysis of peroxidase and esterase indicated that 2 of the 5 green calli, designated Hy 2 and Hy 5, were almost symmetric nuclear hybrids while the other 3 were either asymmetric nuclear hybrids or cybrids. Cytological observa... | | 利用改良的PEG方法以2%的频率诱导黄花烟草原生质体和经IOA失活的枸杞原生体融合。在获得的250块愈伤组织中,有5块为形态上与枸杞愈伤组织类似。对这5块愈伤组织的过氧化物酶和酯酶同工酶分析结果表明,其中的2块(记作Hy2和Hy5)为对称程度较高的体细胞核杂种,其它3块为不对称核杂种或细胞质杂种。细胞学观察指出,Hy2和Hy5的平均染色体数目分别为98.2和59.3。此外,两个杂种的几乎所有中期细胞均含有结构变异的染色体。以小麦rDNA为探针的Southern杂交结果表明,Hy2和Hy5均含有双亲DNA特异片段。从Hy5再生出了形态上介于双亲之间的小苗。对再生苗叶片的酯酶同工酶分析指出,这些小苗含有双亲的特征酶带。 | | 文摘来源 | | Abstract :The determinant role of functional refractory period of atrioventricular node (FRPN) is protecting the ventricles against too early reactivations in various supraventricular tachyarrhythmias including atrial fibrillations, walrants the current practice of determining FRPN in most electrophysiological ivestigations. Different aspects of the intrinsic regulation of rate—induced variations of FRPN were studied in isolated rabbit heart preparations. First, for a constant fast rate, effects of facillit... | | 房室结功能不应期(FRPN)的主要作用在于保护心室免受各种类型的室上性心动过速包括房颤的影响。同时它又是大多数房室结功能不应期电生理研究的目的。木文研究了离体兔心标本FRPN频率依赖的变异性的基本规律。研究的结果表明:(l)在稳定的快速频率条件下,房室结传导的加速性使FRPN缩短,疲劳性使FRPN延长.FRPN是加速性和疲劳性相互作用的结果;(2)加速性和疲劳性诱导的FRPN的变化是在1:l房室传导范围内产生的,并在快速频率下达到它的最大效应;(3)加速性和疲劳性诱导的房室结传导时间的延长和缩短与FRPN密切相关。总之,本项研究已经证实频率诱导的FRPN变异性的根本因素是房室结传导的加速性和疲劳性,推测是因为房室结不同反应的结果. | | 文摘来源 | | Factors affecting the regeneration of wheat plants from immature embryos, such as differences in genotype, size and development stage of immature embryos, duration of 4℃ treatment, ways of inoculation of immature embryos, differentiation and rooting conditions, etc., were studied. And then a high efficiency regeneration system of wheat plants from immature embryos was established (Fig.2). Under optimal conditions, the frequency of embryogenic callus induction from immature embryos was 89 %, and the frequenc... | | 研究探讨了不同的基因型、幼胚取材时期、4℃处理时间、盾片接种方式、分化及生根条件等对小麦幼胚培养再生成株特性的影响 ,并在此基础上建立了一套高效、可靠、重复性好的小麦组培再生系统。优化条件下 ,该系统从幼胚诱导致密愈伤组织的频率为89% ,致密愈伤组织的分化频率诱导 2周时为 95 % ,培养近 3个月时仍可达 5 0 %以上。此外还发现部分叶状结构当转至新鲜的分化培养基上时能够进一步发育成为芽苗。分化的芽苗在生根培养基上大多生成丛生苗。从基部切开后 ,每棵芽苗 /分蘖均可独立成株。组培苗均可正常地开花结实 | | 文摘来源 | |   | | << 更多相关文摘 |
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