家兔脊髓蛛网膜下腔注射乙酰胆碱对血压和心率的影响

将乙酰胆碱(ACh)注入麻醉家兔脊髓蛛网膜下腔,观察其对心血管活动的影响。结果表明:(1)脊髓蛛网膜下腔注射50～100μg ACh可使血压下降,心率减慢;(2)预先由脊髓蛛网膜下腔注射阿托品,可阻断ACh引起的降压和降心率作用;(3)脊髓蛛网膜下腔注射六甲双铵、酚妥拉明或心得安均不能阻断上述ACh的心血管反应;(4)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低血压的作用不受到任何影响。 脊髓中ACh水平升高可通过激活胆碱能M-受体引起血压下降和心率减慢。ACh的这种降压作用既没有中枢肾上腺素能受体活动参与,也不是通过迷走神经实现的,可能是由于脊髓交感血管中枢紧张性降低所造成的。     

大田玉米、高粱、芝麻、豇豆叶片水势、蒸腾速率、气孔阻力对环境因素的反应

本文研究了田间生长的玉米、高梁、芝麻、豇豆在不同土壤供水条件下,叶水势、气孔阻力、蒸腾速率日变化及其与环境因素的关系。结果表明,四种作物气孔开闭与光强密切相关:夜间气孔关闭,rs高;白天气孔开放,rs低。ψ_(WL)、TR与环境因素(气温、RH、ψ_(WV)、光强等)密切相关,它们之间的相关系数(在0.05和0.01水平)显著。四种作物ψ_(WL)日节奏为“正弦曲线”状,13:00—15:00小时ψ_(WL)最低,黎明前最高。中午ψ_(WV)和土壤含水量愈低。ψ_(ML)愈低。四种作物TR在早晨逐斩增高,13:00—15:00小时最强;傍晚前又降低;夜间TR最低。干旱植株ψ_(WL)、TR低于灌水植株,而rs高于灌水植株。     

冬虫夏草多糖的分子结构与免疫活性

 冬虫夏草多糖(在本文中名为CS-81002)是由冬虫夏草菌Cordyceps sinensis(Berk)Sacc在人工发酵条件下产生的胞外多糖。用凝胶过滤法测出CS-81002的分子量Mr=43kD。CS-81002的单糖组成为Man:Gal:Glc=10.3:3.6:1。甲基化分析和部份酸水解结果表明,CS-81002是多分支的杂多糖,由→6)-Manp-(1→形成主链,大约每10个主链Man残基中,有6个在C3位上被取代(即形成→3,6)-Manp-(1→分支),有4个在位C2上被取代(即形成→2,6-Manp-(1→分支),从而形成侧链。主链中还有少许未被取代的Man残基。侧链则由→3-)-Galf-(1→,→4)-Glcf-(1→,→4)-Manp-(1→和→2)-Manp-(1→组成。位于非还原末端的,则三种单糖残基都有。CS-81002在5mg/kg体重×12剂量条件下,对正常的昆明小鼠腹腔巨噬细胞吞噬功能有显著促进作用。在同样剂量条件下,对正常LACA小鼠脾脏溶血斑形成细胞(PFC)对绵羊红细胞的溶血作用无显著影响。不同程度的部份酸水解可使CS-81002的分子量下降,分支减少,并且对巨噬细胞吞噬功能的促进作用亦有下降趋势。在所得到的各个部份酸水解级分(分子量分别为41000,40000,32000,16000和12000)中,分子量为12000的级分对巨噬细胞吞噬功能无促进作用。     

Effect of Protease Inhibitors on Early Events of Apoptosis

Proteolysis is an early event of apoptosis which appears to be associated with activation of the endonuclease which is responsible for internucleosomal DNA cleavage. The present study was designed to reveal the possible role of proteolysis in other early events, such as chromatin condensation, nuclear breakdown, and destabilization ofin situDNA double-stranded structure. Apoptosis of human leukemic HL-60 cells and rat thymocytes was induced by different agents, including DNA topoisomerase inhibitors, an RNA antimetabolite, and the glucocorticosteroid, prednisolone. DNA degradation was evaluated by pulsed field and conventional gel electrophoresis and by the presence ofin situDNA strand breaks. DNA stability was estimated by the measure of its sensitivityin situto denaturation. Chromatin condensation, nuclear breakdown, and other morphological changes were monitored by interference contrast and UV microscopy following cell staining with the DNA-specific fluorochrome 4′,6-diamidino-2-phenylindole. Several irreversible or reversible serine protease inhibitors prevented internucleosomal DNA degradation, nuclear breakdown, and destabilization of DNA double-stranded structure. The effective inhibitors, however, did not prevent the onset of chromatin condensation, nor the loss of the fine structural framework, nor the initial step of DNA cleavage generating DNA fragments of ≥50 kb in size. The data indicate that in both cell systems the activity of proteases sensitive to the inhibitors tested is needed for internucleosomal DNA cleavage to occur. The data also suggest that these proteases may be involved in dissolution of the nuclear envelope. Because nuclear matrix proteins and histones stabilize DNAin situ,and the decrease in DNA stability which occurs during apoptosis is precluded by the inhibitors, it is likely that serine proteases may degrade DNA stabilizing proteins. The activity of these proteases, however, appears needed neither for DNA cleavage to ≥50-kb fragments nor for the onset of chromatin condensation which is associated with dissolution of the structural framework of the nucleus.     

Elevated CO2 alters anatomy,physiology, growth,and reproduction of red mangrove (Rhizophora mangle L.)

Mangroves, woody halophytes restricted to protected tropical coasts, form some of the most productive ecosystems in the world, but their capacity to act as a carbon source or sink under climate change is unknown. Their ability to adjust growth or to function as potential carbon sinks under conditions of rising atmospheric CO₂ during global change may affect global carbon cycling, but as yet has not been investigated experimentally. Halophyte responses to CO₂ doubling may be constrained by the need to use carbon conservatively under water-limited conditions, but data are lacking to issue general predictions. We describe the growth, architecture, biomass allocation, anatomy, and photosynthetic physiology of the predominant neotropical mangrove tree, Rhizophora mangle L., grown solitarily in ambient (350 ll^–1) and double-ambient (700 ll^–1) CO₂ concentrations for over 1 year. Mangrove seedlings exhibited significantly increased biomass, total stem length, branching activity, and total leaf area in elevated CO₂. Enhanced total plant biomass under high CO₂ was associated with higher root:shoot ratios, relative growth rates, and net assimilation rates, but few allometric shifts were attributable to CO₂ treatment independent of plant size. Maximal photosynthetic rates were enhanced among high-CO₂ plants while stomatal conductances were lower, but the magnitude of the treatment difference declined over time, and high-CO₂ seedlings showed a lower P_max at 700 ll^–1 CO₂ than low-CO₂ plants transferred to 700 ll^–1 CO₂: possible evidence of downregulation. The relative thicknesses of leaf cell layers were not affected by treatment. Stomatal density decreased as epidermal cells enlarged in elevated CO₂. Foliar chlorophyll, nitrogen, and sodium concentrations were lower in high CO₂. Mangroves grown in high CO₂ were reproductive after only 1 year of growth (fully 2 years before they typically reproduce in the field), produced aerial roots, and showed extensive lignification of the main stem; hence, elevated CO₂ appeared to accelerate maturation as well as growth. Data from this long-term study suggest that certain mangrove growth characters will change flexibly as atmospheric CO₂ increases, and accord with responses previously shown in Rhizophora apiculata. Such results must be integrated with data from sea-level rise studies to yield predictions of mangrove performance under changing climate.     

大豆子叶内酸性磷酸酶活性的超微结构定位

开花后３５～５０ ｄ 期间和萌发早期（播种后４～８ ｄ）的大豆（Ｇｌｙｃｉｎｅｍ ａｘ Ｌ．）种子中,酸性磷酸酶主要分布在子叶细胞中的蛋白体内;在内质网内也检测到酸性磷酸酶活性。此外,在萌发早期的部分子叶细胞的质膜外侧及其细胞壁基质中可见密集的酸性磷酸酶活性;而且在近质膜的胞质中常见到一些富含磷酸铅沉淀的胞质小泡,似与质膜融合     

小麦×玉米杂交后代的蛋白质及酯酶同工酶分析

以８ 个普通小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．）品种为母本,２ 个栽培玉米（Ｚｅａ ｍ ａｙｓ Ｌ．）品种为父本杂交所获得的Ｆ２ 代在形态上出现了明显变异。对其籽粒进行蛋白质电泳分析,得到了如下主要结果：杂交后代的蛋白质谱带较母本有了很大的变异,主要集中在高分子量麦谷蛋白（ＨＭＷ－Ｇｌｕ）区域。杂交后代的蛋白质谱带由５ 种类型构成：１．母本型,占全部测试籽粒的２２．６％ ;２．附加型,占１４．３％ ;３．互补型,占１５．５％ ;４．杂种型,占３０．９％ ;５．缺失型,占１６．７％ 。对“矮杆早”ד紫粘”的Ｆ２ 代籽粒进行酯酶同工酶电泳分析发现,变异主要发生在ＥＳＴ－１ 区。由此看来,小麦×玉米的杂合子中玉米染色体在被排除前后,可以诱发小麦染色体组发生遗传变异     

大豆结瘤突变体成分的初步分析及其对硝酸还原酶活性和结瘤的影响

超结瘤大豆（Ｇｌｙｃｉｎｅ ｍ ａｘ （Ｌ．） Ｍｅｒｒ．） ｎｔｓ ３８２ 和不结瘤大豆Ｎｏｄ ４９ 的叶和根组织水提取物经Ｓｅｐｈａｄｅｘ Ｇ２５ 过滤、洗脱,再根据洗脱物对硝酸还原酶（ＮＲ）活性的影响可划分为４ 个组分（ｆｒａｃｔｉｏｎ）样品,即ｎｔｓ ３８２（Ｎｏｄ ４９） Ｆ１、ｎｔｓ ３８２（Ｎｏｄ ４９） Ｆ２、ｎｔｓ ３８２（Ｎｏｄ ４９） Ｆ３ 和ｎｔｓ ３８２（Ｎｏｄ ４９） Ｆ４。其中, ｎｔｓ３８２ Ｆ２ 和Ｆ４ 抑制ＮＲ 活性作用在接种ＵＳＤＡ１１０ 后明显下降, 但接种的ｎｔｓ ３８２ Ｆ２ 却能提高大豆Ｂｒａｇｇ 的结瘤数达一倍, 而接种的ｎｔｓ ３８２ Ｆ３ 和Ｆ４ 的作用不明显。ＮＲ 活性抑制因子不是刺激结瘤的因子, 刺激结瘤的因子主要分布在接种的ｎｔｓ３８２ Ｆ２ 部分中。与这一现象相反, Ｎｏｄ ４９ Ｆ２ 和Ｆ４ 抑制ＮＲ活性的作用在接种后更强, 且也抑制大豆ｎｔｓ ３８２ 的结瘤, 其中Ｎｏｄ ４９ Ｆ４ 抑制结瘤的作用基本不能逆转。抑制结瘤因子主要分布在接过种的Ｎｏｄ ４９ Ｆ４ 部分中     

细胞分裂素生物合成基因在调节一组烟草病理相关蛋白基因表达中的作用

对一组病理相关蛋白基因在烟草 ( N icotiana tabacum cv. Wisconsin 38)中的表达情况进行了研究 ,包括 :碱性几丁质酶、β- 1 ,3-葡萄糖苷酶、渗透蛋白及伸展蛋白。RNA杂交实验表明在正常烟草植株中上述 4个基因具有发育和器官专一性的表达。在含有细胞分裂素生物合成基因的转基因烟草丛生芽中 ,这 4个基因的表达受过量合成的内源细胞分裂素和载体效应的共同调节 ,细胞分裂素降低这些基因的表达 ,而载体效应则促进它们的表达。热激处理也明显降低这 4种基因的表达水平。上述结果表明这些病理相关蛋白基因具有复杂的调控系统