瓜子金皂甙丙和丁的化学结构研究

自草药瓜子金(Polygala japonica Houtt)地上部分又分离得到两种皂甙,即瓜子金皂甙丙和皂甙丁,它们的分子式均为 C_(42)H_(68)O_(15),为同分异构物。两者酸水解均得瓜子金皂甙元和 D-葡萄糖,但碱水解时,只有皂甙丁可被水解,产物和酸水解相同。经~1HNMR,~(13)CNMR,MS 推定它们的结构式,瓜子金皂甙丙为3-O-[β-D-葡萄吡喃糖(1→2)-β-D-葡萄吡喃糖]瓜子金皂甙元;而瓜子金皂甙丁为28-O-[β-D-葡萄吡喃糖(1→2)-β-D-葡萄吡喃糖]瓜子金皂甙元。上述两种皂甙均为新化合物。     

皖南、赣北奥陶纪笔石立体标本形成环境的初步研究*

皖南、赣东北和赣西北地区奥陶纪笔石地层发育良好,笔石化石丰富。宁国组和胡乐组均为笔石相地层,但笔石的保存特点并不相同。立体保存的黄铁矿化笔石标本主要见于宁国组,而胡乐组的笔石几乎均为薄膜标本。在比较宁国组和胡乐组在岩性、颜色、化石、矿物和元素等方面的特点后发现,两者有较明显的差异。这表明宁国组和胡乐组形成时的环境是不同的,前者为弱还原环境,后者为较强的还原环境,而在研究区内影响笔石体立体保存的主要因素为还原环境和较高的铁含量。在还原环境下,铁可呈Fe~(2+)存在,笔石体内含有硫,死亡后经降解作用可生成H_2S;H_2S和Fe~(2+)结合可使笔石体黄铁矿化,从而使笔石体硬化而呈立体保存下来。宁国组的铁含量明显高于胡乐组,这似可以解释宁国组产有较多笔石立体标本的原因。     

慢性缺氧对肺动脉内皮依赖性和非内皮依赖性舒张反应的影响

本实验用生物测定法观察了模拟海拔5000m高度连续缺氧20d对大鼠肺动脉内皮依赖性和非内皮依赖性舒张反应的影响。结果显示慢性缺氧明显抑制了肺内和肺外动脉对乙酰胆碱、ATP、硝普钠和异丙肾上腺素舒张反应的敏感性和反应性。在浓度为10~(-6)mol/L时,缺氧组大鼠肺内动脉对乙酰胆碱、硝普钠和异丙肾上腺素的舒张反应分别只有对照组大鼠的61.3％、75.9％和61.7％,对浓度为1.8×10~(-5)mol/L的ATP的舒张反应只有对照组大鼠的64.9％。研究表明,ATP和乙酰胆碱主要是通过内皮舒张因子使肺动脉产生内皮依赖性舒张反应,硝普钠和异丙肾上腺素分别通过直接激活血管平滑肌细胞鸟苷酸环化酶和β受体使血管产生非内皮依赖性舒张反应。缺氧同时抑制了肺动脉内皮依赖性和非内皮依赖性舒张反应,提示慢性缺氧可能抑制了正常肺内舒血管活性物质的生理作用。     

流域开发生态建设发展战略

以往研究流域开发战略问题,多从流域内资源的开发利用方面考虑,而衡量其方案的优劣也多以经济效益的大小为准绳。现在,环境污染与生态危机已威胁着人类的生存与发展,因此在研究流域战略问题时,必须开拓思路,     

31例非特异性阴道炎病人阴道微生物群的研究

本文对31例非特异性阴道炎病人和31例正常人阴道微生物群进行定性、定量分析.结果表明,阴道炎病人的阴道乳杆菌的平均浓度明显低于正常人,而肠杆菌科、葡萄球菌、棒状杆菌、类杆菌属、支原体却明显增多,阴道炎病人未发现特异性病原体,菌群失调可能是其发病因素。乳杆菌为阴道正常优势菌,对改善阴道的微环境,防止条件致病菌引起的内源性感染具有重要的生理作用。     

Swelling and Ca2+-activated Anion Conductances in C127 Epithelial Cells Expressing WT and ΔF508-CFTR

CFTR is a chloride channel that is required for fluid secretion and salt absorption in many exocrine epithelia. Mutations in CFTR cause cystic fibrosis. CFTR expression influences some ion channels, but the range of channels influenced, the mechanism of the interaction and the significance for cystic fibrosis are not known. Possible interactions between CFTR and other ion channels were studied in C127 mouse mammary epithelial cell lines stably transfected with CFTR, ΔF508-CFTR, or vector. Cell lines were compared quantitatively using an ¹²⁵I efflux assay and qualitatively using whole-cell patch-clamp recording. As expected, ¹²⁵I efflux was significantly increased by forskolin only in the CFTR line, and forskolin-stimulated whole-cell currents were time- and voltage independent. All three lines responded to hypotonic challenge with large ¹²⁵I efflux responses of equivalent magnitude, and whole-cell currents were outwardly rectified and inactivated at positive voltages. Unexpectedly, basal ¹²⁵I efflux was significantly smaller in the ΔF508-CFTR cell line than in either the CFTR or control cell lines (P < 0.0001), and the magnitude of the efflux response to ionomycin was largest in the vector cell line and smallest in the cell line expressing ΔF508-CFTR (P < 0.01). Whole-cell responses to ionomycin had a linear instantaneous I-V relation and activated at depolarizing voltages. Forskolin responses showed simple summation with responses to ionomycin or hypotonic challenge. Thus, we found no evidence for interactions between CFTR and the channels responsible for swelling-mediated responses. Differences were found in basal and ionomycin-stimulated efflux, but these may arise from variations in the clonally selected cell lines that are unrelated to CFTR expression. Received: 15 November 1995/Revised: 16 February 1996     

蓝藻藻胆体与类囊体膜之间光能传递的研究

从嗜热蓝藻优雅粘囊藻（Ｍｙｘｏｓａｒｃｉｎａ ｃｏｎｃｉｎｎａ Ｐｒｉｎｔｚ．）中分离到具有放氧活性的藻胆体－类囊体膜复合物。它的吸收峰位于６８０、６２８、４９０、４３８和４２０ ｎｍ ,在低离子强度（０．１～０．４ ｍ ｏｌ／Ｌ）磷酸缓冲液中的６６４ ｎｍ 荧光发射峰随离子强度的降低而升高,７１８ ｎｍ 荧光发射峰与此相反（７７ 。Ｋ,Ｅｘ＝ ５８０ ｎｍ ）。当把游离的藻胆体和已解离去藻胆体的类囊体膜在蔗糖磷酸缓冲液中重组时,随时间延长（０～６０ ｍ ｉｎ）,７１８ ｎｍ 荧光发射峰逐渐升高,６８５ ｎｍ 荧光发射峰逐渐下降（７７ 。Ｋ,Ｅｘ ＝ ５８０ ｎｍ ）,表明藻胆体与类囊体之间的解离和结合对光能传递的影响     

生物复苏——大绝灭后生物演化历史的第一幕

生命史是一部生物界短期,快速剧变与长期,慢速稳定相互交替的历史。大绝灭（即集群绝灭）事件反映了全球环境的大突变,点断了地质历史中的生命记录及其发展历程,预示着生物界的演化出现了最有意义的飞跃,近年来尝试研究大绝灭后全球生物界的残存－复苏及其基本型式,并探索复苏的控制因素,标志着地质科学中一个重心的转移（即从大绝灭转向其后的生物残存与复苏的研究）。生物复苏揭示了大绝灭后生物演化历史的第一幕,其研究的