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61.
人参根系发育形态学的研究 总被引:5,自引:0,他引:5
人参(Panax qinseng C. A. Meyer)属于直根系植物,有次生构造。一年生苗只具有主根和侧根。二年以上的人参常在根状茎上长出不定根,即人参根系包括主根和不定根及其各级分枝。主根初生木质部为三原型,侧根和不定根及其分枝多为二原型,偶见三原型。根系随参龄的增加而增大。每年末级分枝自基部于休眠前萎缩、脱落,并在萎缩部分的上一级支根内部产生越冬根原基,越冬根原基是翌年形成全部吸收根的基础。一年生人参由中柱鞘产生一圈初生树脂道,由形成层产生一圈(或二圈)次生树脂道,以后次生树脂道的圈数随参龄的增加而每年增加一圈,自第五年开始渐缓。根内淀粉粒含量随发育时期的变化而相应变化,其积累高峰出现在果后期。研究人参根系发育形态学不仅对全面正确认识人参根系具有理论意义,而且对改进人参栽培管理和评价人参质量具有指导意义。 相似文献
62.
促性腺激素诱导猕猴排卵周期中卵巢纤溶酶原激活因子与抑制因子的变化 总被引:1,自引:0,他引:1
在用 PMSG 和 hUG 诱导猕猴排卵过程中,我们研究了 pA 和它的抑制因子 PAI-1与排卵的关系。实验结果表明,由促性腺激素所诱导出的卵巢 tPA 活性的增加与排卵密切相关,在排卵前达到高峰,而排卵后明显下降;uPA 只在排卵后的颗粒细胞大量出现;PAI-1分泌高峰比 tPA 峰值早出现12—24小时;排卵来临时,tPA 的明显上升导致 PAl-1的空然下降。上述实验结果说明,卵巢中 tPA 和 PAI-1活性的这种平衡性的变化可能在排卵机制和维持卵巢的正常生理功能中起重要作用,而 uPA 或许与黄体形成的调节有某些关系。 相似文献
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65.
Blue Light-Induced Phototropic Response and the Intracellular Photoreceptive Site in Adiantum Protonemata 总被引:1,自引:0,他引:1
Blue light-induced phototropism in Adiantum protonemata wasinvestigated with microbeam irradiation. Brief irradiation withblue light effectively induced a phototropic response when itwas applied to a half-side of the apical 200d µm regionof a protonema. The phototropic response was partly reversedby the subsequent far-red light irradiation but the full reversalof the response was not observed even when the fluence of far-redlight was increased. In the far-red reversible part of the response,blue/far-red photoreversibility was repeatedly observed. Thus,both phytochrome and a blue light-absorbing pigment (other thanphytochrome) seem to be involved in the blue light-induced phototropicresponse in Adiantum protonemata. Furthermore, detailed studiesof the far-red light effect on the fluence-response curve forblue lightinduced phototropism revealed that the concomitantmediation by the two receptors was limited to the response inthe relatively higher fluence range of blue light and that theblue light-absorbing pigment alone was responsible in the lowerfluence range. In the higher fluence range, the response mediatedby the blue light-absorbing pigment became saturated and thephytochrome response became evident, indicating a differencein the sensitivities of the two receptor pigments to blue light. When various regions of half-sides of protonemata were irradiatedwith a blue microbeam of 10 µm width, irradiation at theapical 525 µm region was most effective both forphytochrome- and blue light-absorbing pigment-mediated response,indicating that the site of blue light perception is almostidentical for each response. (Received July 14, 1986; Accepted September 26, 1986) 相似文献
66.
Mu-Chin Tzeng Ming Jhy Hseu Jun Hai Yang Richard John Guillory 《The protein journal》1986,5(3):221-228
Snake presynaptic toxins such as crotoxin, β-bungarotoxin and taipoxin block neuromuscular transmission through inhibiting the release of acetylcholine by their phospholipase A2 activities. On the other hand, many other phospholipase A2s show little neurotoxicity. It is likely that the difference lies in whether high affinity binding to nerve cell membranes exists or not. To test this idea, crotoxin, β-bungarotoxin and taipoxin were first radioactively labeled with Na(125I) without loss of their neurotoxicity. Using the radioactive toxins we have found that each of the three showed specific binding to synaptosomal membranes from guinea pig brain. In contrast, we could not detect specific binding of a non-neurotoxic pancreatic phospholipase A2. Crotoxin and taipoxin, but not β-bungarotoxin, also bound specifically to membrane preparation from other tissues. The binding of each toxin was not greatly affected by the other two toxins. The photoaffinity labeling technique has been used to obtain further information about the components which bind crotoxin. For this purpose, (125I) crotoxin was derivatized with N-hydroxysuccinimidyl-4-azidobenzoate. Autoradiographic analysis of the membranes following photoirradiation in the presence of the modified crotoxin revealed that an 85K dalton component was preferentially covalently conjugated with the crotoxin analogue in a specific manner. 相似文献
67.
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69.
利血平和丘脑下部促黄体素释放激素类似物(LHRH-A)对大鳞副泥鳅促性腺激素细胞的分泌活动和排卵的促进作用 总被引:3,自引:1,他引:2
利血平能使神经分泌细胞的儿茶酚胺贮存量减少甚至消耗殆尽,导致多巴胺作为GRIF的作用减弱,从而显著增强LHRH-A促进GtH分泌和诱导排卵的效应。对大鳞副泥鳅,利血平和LHRH-A同时注射或者利血平比LHRH-A提前3小时注射,都能激活GtH细胞,显著增强其分泌活动并诱导排卵。利血平的最低有效剂量为1—5微克/克体重。利血平(25微克/克体重) LHRH-A(0.05微克/克体重)的催产效果和多巴胺拮抗物pimozide(1微克/克体重) LHRH-A(0.05微克/克体重)的催产效果一样,排卵率都达到了100%。 相似文献
70.
Terry Joe Sprinkle F. Arthur McMorris Jun Yoshino George H. De Vries 《Neurochemical research》1985,10(7):919-931
The relative levels of the central nervous system myelin marker enzyme 2:3-cyclic nucleotide 3-phosphodiesterase (EC 3.1.4.37, CNPase) were determined in neuroblastoma, astrocyte, oligodendrocyte and Schwann cell cultures and in freshly isolated human lymphocytes and platelets. The highest specific activities were associated with the cells that elaborate myelin membrane in the central and peripheral nervous system, oligodendrocytes and Schwann cells, respectively. Antiserum to bovine CNPase recognized both CNP1 and CNP2 in CNS myelin and human oligodendroglioma. In addition, a 53,000 dalton protein was evident on autoradiographs of immunoblotted PNS myelin and human oligodendroglioma proteins. Cultured rat oligodendrocyte, C6 and mouse NA neuroblastoma CNPase appear to share common determinants with the corresponding normal rat CNS enzyme. 相似文献