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131.
应用标志-释放-回收技术研究小皱蝽成虫的主要种群特征,结果如下:(1)成虫扩散的偏离度Ku=2.4,为一阶峻开曲线;(2)分别用Peterson和Jackson方法对种群蜜度进行了估计,结果表明,Jackson的方法较好;(3)雄虫平均寿命40-45,虫平均寿命120-130。天。 相似文献
132.
云南西部不同生境区域革螨群落的模糊聚类分析 总被引:8,自引:0,他引:8
云南西部10个不同生境区域小兽体表革螨群落经用模糊聚类分析,归并为4种群落类型:华南区室内生境型、华南区室外农耕地生境型、西南区室内生境型及西南区室外农耕地生境型。研究表明,生境的不同或在动物地理上位置的不同导致了革螨群落的差异。 相似文献
133.
濒危植物——长喙毛茛泽泻的雌雄配子体发育 总被引:2,自引:0,他引:2
长喙毛茛泽泻 Ranalisma rostratum stapf 小孢子母细胞的减数分裂过程为连续型,四分体为左右对称型。成熟花粉为三胞花粉。花药绒毡层为变形绒毡层。雌蕊由多数单室子房构成,每子房中含一具双珠被、薄珠心的倒生胚珠。胚囊发育为葱型。成熟胚囊中三个反足细胞退化;二个极核分别位于中央细胞的两端,其体积相差明显。这种极核分布可能与反足细胞过早退化有关。 相似文献
134.
135.
肝细胞生长因子mRNA在成年小鼠和人胎儿不同器官中的表达 总被引:2,自引:0,他引:2
本实验从成年小鼠和胎龄4-5月的人胎儿不同器官中分离总RNA。经斑点印迹分析显示,肝细胞生长因子(HGF)mRNA在成年KM小鼠多种器官中表达,其表达水平由高到低依次为:肺、肝、肾、卵巢、睾丸、大脑和胃;在脾、心、骨髓、小肠和骨骼肌组织中以HGFmRNA。在胎龄4-5月的人胎儿中,HGFmRNA表达水平由高到低依次为:大脑、肝、腮腺、胃、小肠、肾、心和骨骼肌;肺和脾组织为阴性。由此可见,HGF在成 相似文献
136.
Synthesis of human insulin gene. VIII. Construction of expression vectors for fused proinsulin production in Escherichia coli 总被引:18,自引:0,他引:18
Analysis of Tn1725 insertions in the Pif+ plasmid pRS2496 showed the maximum limits of the F pif region to be between 43.7 and 47.15 on the 100-kb map of the F plasmid. The effect of these insertions on the expression of pif polypeptides indicated that two of the pif genes, pifA and pifC, lie within a polycistronic operon. 相似文献
137.
本文研究结果表明低剂量的氦氖激光可以提高绵羊精清中GOT和LDH酶的活性,并对其机制作了初步的探讨。 相似文献
138.
Oscillations in free cytosolic calcium during IgE-mediated stimulation distinguish human basophils from human mast cells 总被引:1,自引:0,他引:1
Free cytosolic calcium ([Ca2+]i) levels increase after the stimulation of either human basophils or mast cells with anti-IgE antibody. Previous studies found that the mast cell [Ca2+]i response was graded in magnitude, according to stimulus strength, and that the activated level was free of oscillations. The current studies demonstrate several new features of the mast cell and basophil response. First, in mast cells, the transition to activated [Ca2+]i levels was abrupt (width = 6.5 +/- 2 s), after a period of quiescence whose duration (5 to 300 s) was a function of the strength of the stimulus. At optimal concentrations of anti-IgE, 97% of mast cells showed only abrupt transitions and oscillation-free activated calcium levels. In contrast, basophils showed marked oscillations whose magnitudes were partially dependent on the strength of stimulus. Like the mast cell, there was a quiescent period before the first transition and this period was also dependent on the strength of the stimulus. Oscillations were generally superimposed on an elevated [Ca2+]i level at a frequency of 0.5 to 3/min, had half-widths of 5 to 20 s, and were markedly chaotic in the frequency domain. In general, oscillations were more apparent at suboptimal concentrations of anti-IgE. Despite the apparent contrast in basophil and mast cell responses, oscillations (1 or 2 in a 10-min period) could be observed in a small percentage of mast cells and some basophils showed characteristics of mast cells. We tentatively conclude that mast cells and basophils utilize a similar mechanism of calcium mobilization but that the nonlinear characteristics of the calcium response may account for the mast cell/basophil differences. These studies indicated that the calcium kinetics, as measured by population averages, did not reflect the kinetics observed at the single cell level. Both mast cells and basophils had characteristics which could be described as graded and characteristics resembling all-or-nothing processes; the magnitude of a response was graded according the strength of stimulus while the kinetics profile appeared as an all-or-nothing event. 相似文献
139.
Endotoxin-induced cytokine gene expression in vivo. III. IL-6 mRNA and serum protein expression and the in vivo hematologic effects of IL-6 总被引:19,自引:0,他引:19
T R Ulich K Z Guo D Remick J del Castillo S M Yin 《Journal of immunology (Baltimore, Md. : 1950)》1991,146(7):2316-2323
Endotoxin (LPS) at sublethal doses injected i.v. into rats was found to induce IL-6 mRNA expression peaking at 1 to 2 h in whole organ RNA preparations of the spleen, liver, lung, bowel, and kidney. IL-6 serum protein levels also peaked at 2 h. TNF and IL-1, generally considered to be among the most rapidly released cytokines, also induced IL-6 expression. IL-6 in turn inhibited TNF and IL-1 expression, suggesting that IL-6 may be part of a negative feedback mechanism in the cytokine cascade. Dexamethasone down-regulated and Corynebacterium parvum up-regulated IL-6 expression, although the possibility cannot be excluded that these immunomodulating factors may in part have exerted their effects indirectly via the up- and down-regulation of TNF and IL-1. IL-6 injected i.v. at a pathophysiologically relevant dose caused a peripheral neutrophilia and mild myeloproliferative effect in the bone marrow. 相似文献
140.
Ming Guo Lawrence T. Kim Steven K. Akiyama Harvey R. Gralnick Kenneth M. Yamada Frederick Grinnell 《Experimental cell research》1991,195(2):315-322
We used monoclonal antibodies against specific integrin subunits to examine the role of integrin receptors in keratinocyte activation. We found that before activation, beta 1 subunits in keratinocytes showed a diffuse distribution, whereas after activation, keratinocytes organized beta 1 receptors into marginal adhesion plaques. In immunoprecipitation experiments with antibodies against beta 1 integrin subunits, we found mostly immature subunits synthesized in keratinocytes freshly harvested from skin. Moreover, integrin receptor complexes immunoprecipitated from these cells by monoclonal antibodies against alpha 2, alpha 3, or alpha 5 subunits contained only immature beta 1 subunits. With keratinocytes cultured 4-7 days, anti-beta 1 antibodies immunoprecipitated mostly mature beta 1 subunits, and integrin complexes immunoprecipitated from cultured cells by anti-alpha subunit antibodies contained mostly mature beta 1 subunits. Antibodies directed against beta 1 subunits also inhibited keratinocyte migration. Based on these results, we suggest that up-regulation of migration by activated keratinocytes depends on changes in processing of pre-beta 1 subunits to mature beta 1 subunits. We also studied the distribution of integrin subunits in skin and on keratinocytes migrating out of skin explants. Whereas beta 1, alpha 2, and alpha 3 subunits were detected in keratinocytes in skin and migrating out of explants, alpha 5 subunits were observed only in migrating cells. 相似文献