质粒YRP7的基本特性鉴定

质粒YRP7用氯霉素法扩增,碱变性裂解法提取,酸酚法及核糖核酸酶纯化后,得到了高产量(5.6mg/L培养液),高纯度(A260:A280=2.0)的质粒制品,经转化实验及酶切分析确定YRP7具有下列特征:大小为5.41±0.10kb,可赋予宿主细胞AmP~r、Tet~r的表型,对大肠杆菌C600的转化频率为10~(-6)、转化效率为1.5×10~6转化子/mgDNA。限制性内切酶BamH Ⅰ、ECoRⅠ、Hind Ⅲ及PstⅠ在其分子上的切点数分别为1、2、2、2,并确定了各酶切片段的分子大小,对BanHⅠ的单切点,经插入失活法证实其位于Tet~r的基因上。由上述特征可确定,质粒YRP7是一个比较理想的克隆载体。     

Variations in Immune Response of Popillia japonica and Acheta domesticus to Heterorhabditis bacteriophora and Steinernema Species

The infectivities of Steinernema carpocapsae, S. glaseri, S. scapterisci, and Heterorhabditis bacteriophora to Japanese beetle larvae, Popillia japonica, and house cricket adults, Acheta domesticus, were compared using external exposure and hemocoelic injection. Only H. bacteriophora and S. glaseri caused high P. japonica mortality after external exposure. When nematodes were injected, P. japonica had a strong encapsulation and melanization response to all species except S. glaseri. Heterorhabditis bacteriophora and S. carpocapsae were able to overcome the immune response, but S. scapterisci was not. All species except S. scapterisci were able to kill and reproduce within the host. Only S. scapterisci and S. carpocapsae caused A. domesticus mortality after external exposure. When nematodes were injected, A. domesticus had a strong immune response to all species except S. scapterisci. Steinernema carpocapsae effectively overcame the strong immune response and caused high host mortality, but S. glaseri and H. bacteriophora did not. Steinernema scapterisci caused high host mortality and reproduced, S. glaseri and H. bacteriophora caused low host mortality but only S. glaseri reproduced, and S. carpocapsae was able to kill the host but reproduced poorly. Most (ca. 90%) of the S. carpocapsae in the hemocoel of P. japonica became encapsulated and melanized within 8 hours postinjection. The symbiotic bacterium, Xenorhabduf nematophilus, was often released before this encapsulation and melanization.     

小麦体细胞胚发生的超微结构研究

对小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．）幼胚培养中体细胞胚发生过程的超微结构变化进行了研究,结果如下：（１）原体细胞中大液泡消失,存在大量小液泡,细胞质的电子密度加强,核大,核仁明显,出现多核仁;（２）细胞器数量和种类,如质体、核糖体和线粒体增加;（３）细胞壁加厚,胞间连丝逐渐消失,细胞器数量丰富,胚性细胞中积累淀粉;（４）细胞壁加厚的胚性细胞中存在核仁液泡、自体吞噬泡和分泌泡;（５）多细胞原胚、球形胚和梨形胚被一层外壁包围,但胚体内细胞间广泛存在胞间连丝;（６）成熟胚生长点部位的细胞内质体中出现膜系结构,已向叶绿体转变,类囊体已形成     

大黄素对豚鼠结肠带平滑肌细胞电和收缩性能的影响

联合应用平滑肌肌力张力测量技术和细胞内微电极记录技术,同步地现测豚鼠结肠带平滑肌自发的肌源性电活动和力学活动,研究了大黄素的药物作用。大黄素能缩短膜电位的波动周期,从而缩短峰电位集簇发放的周期;相应地,可使平滑肌的分节律收缩加快,幅值指数升高。大黄素又能促使细胞膜电位自发的周期性波动的出现,导致峰电位的集簇发放;相应地,可使强直收缩转化为分节律收缩,即促进收缩形式向有利于肠道推进功能的方向转化。以上结果表明,大黄素能有效地提高豚鼠结肠带平滑肌细胞的电兴奋性和收缩功能,并且对其电学和力学活动的影响之间有明确的对应关系。     

烟碱对乙酰胆碱诱发豚鼠回肠收缩作用的调节

在离休豚鼠回肠标本上,ＡＣｈ诱发双相收缩反应：早期相收缩反应持续时间短,与神经节Ｎ受体有关;后期相收缩反应持续时间长,与平滑肌Ｍ受体有关。烟碱１０μｍｏｌ／Ｌ预孵育后,标本对烟碱激动神经节Ｎ受体诱发的收缩作用产生急性耐受,而ＡＣｈ激动平滑肌Ｍ受体诱发的收缩作用增强。     

Studies on atrophic change of soleus muscle and its countermeasures in suspended rat

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.     

10CM短柱快速分离3-MH的实验研究

本研究在改进后短程序基础上,对氨基酸分离柱进行了改进。改进后的分离柱长为10cm。比原来20cm长柱分离3—MH的时间缩短了近1/2。实验所得的(回收率为97.59%,分离度0.89±0.02。变异系数1.17)这些指标较国外用其它方法所得的结果有良好的相关性。多次测定结果说明长柱与短柱比较无明显差异。证明了短柱对3—MH含量无影响。这一改进所建立的方法大大地缩短了样品的分析时间,节约了大量进口试剂,开展这方面的工作将有利益提高严重烧伤、创伤后蛋白质代谢和营养学等方面的研究水平。     

Loss of DNA repair mechanisms in cardiac myocytes induce dilated cardiomyopathy

Cardiomyopathy is a progressive disease of the myocardium leading to impaired contractility. Genotoxic cancer therapies are known to be potent drivers of cardiomyopathy, whereas causes of spontaneous disease remain unclear. To test the hypothesis that endogenous genotoxic stress contributes to cardiomyopathy, we deleted the DNA repair gene Ercc1 specifically in striated muscle using a floxed allele of Ercc1 and mice expressing Cre under control of the muscle-specific creatinine kinase (Ckmm) promoter or depleted systemically (Ercc1^−/D mice). Ckmm-Cre^+/−;Ercc1^−/fl mice expired suddenly of heart disease by 7 months of age. As young adults, the hearts of Ckmm-Cre^+/−;Ercc1^−/fl mice were structurally and functionally normal, but by 6-months-of-age, there was significant ventricular dilation, wall thinning, interstitial fibrosis, and systolic dysfunction indicative of dilated cardiomyopathy. Cardiac tissue from the tissue-specific or systemic model showed increased apoptosis and cardiac myocytes from Ckmm-Cre^+/-;Ercc1^−/fl mice were hypersensitive to genotoxins, resulting in apoptosis. p53 levels and target gene expression, including several antioxidants, were increased in cardiac tissue from Ckmm-Cre^+/−;Ercc1^−/fl and Ercc1^−/D mice. Despite this, cardiac tissue from older mutant mice showed evidence of increased oxidative stress. Genetic or pharmacologic inhibition of p53 attenuated apoptosis and improved disease markers. Similarly, overexpression of mitochondrial-targeted catalase improved disease markers. Together, these data support the conclusion that DNA damage produced endogenously can drive cardiac disease and does so mechanistically via chronic activation of p53 and increased oxidative stress, driving cardiac myocyte apoptosis, dilated cardiomyopathy, and sudden death.     

Role of pulmonary epithelial arginase-II in activation of fibroblasts and lung inflammaging

Elevated arginases including type-I (Arg-I) and type-II isoenzyme (Arg-II) are reported to play a role in aging, age-associated organ inflammaging, and fibrosis. A role of arginase in pulmonary aging and underlying mechanisms are not explored. Our present study shows increased Arg-II levels in aging lung of female mice, which is detected in bronchial ciliated epithelium, club cells, alveolar type 2 (AT2) pneumocytes, and fibroblasts (but not vascular endothelial and smooth muscle cells). Similar cellular localization of Arg-II is also observed in human lung biopsies. The age-associated increase in lung fibrosis and inflammatory cytokines, including IL-1β and TGF-β1 that are highly expressed in bronchial epithelium, AT2 cells, and fibroblasts, are ameliorated in arg-ii deficient (arg-ii^−/−) mice. The effects of arg-ii^−/− on lung inflammaging are weaker in male as compared to female animals. Conditioned medium (CM) from human Arg-II-positive bronchial and alveolar epithelial cells, but not that from arg-ii^−/− cells, activates fibroblasts to produce various cytokines including TGF-β1 and collagen, which is abolished by IL-1β receptor antagonist or TGF-β type I receptor blocker. Conversely, TGF-β1 or IL-1β also increases Arg-II expression. In the mouse models, we confirmed the age-associated increase in IL-1β and TGF-β1 in epithelial cells and activation of fibroblasts, which is inhibited in arg-ii^−/− mice. Taken together, our study demonstrates a critical role of epithelial Arg-II in activation of pulmonary fibroblasts via paracrine release of IL-1β and TGF-β1, contributing to pulmonary inflammaging and fibrosis. The results provide a novel mechanistic insight in the role of Arg-II in pulmonary aging.