Extractive fermentation of lactic acid by immobilizedLactobacillus casei using ion—exchange resin

Summary A novel method of lactic acid fermentation byLactobacillus casei immobilized in Ca—alginate gels is described, in which an ion—exchange resin packed column is attached to a fermentor for separation of lactic acid from fermentative broth. The technique successfully alleviated the restriction imposed by lactic acid on bacterial growth and product formation. As compared to the conventional batch fermentation, the new fermentation technique enhanced the lactic acid productivity and sugar conversion rate from 0.328g/L·h and 88. 2% to 0.482g/L·h and 98.6%, respectively.     

甘薯象空间格局及抽样技术研究

通过空间分布型指数分析,甘薯象对薯块、著株危害空间分布型为随机分布或均匀分布;同时确定了理论抽样数     

霍山三种石斛与其栽培土壤中微量元素分布关系研究

本文应用灰色系统理论,对安徽霍山三种石斛与其栽培土壤中15种微量元素分布状况进行了关联分析．结果发现.其关联序为γ_根＞γ_叶＞γ_茎;γ_(-年茎)≈γ_(二年茎)≈γ_(三年茎);γ_(霍斛)＞γ_(铁斛)＞γ_(铜斛).可见霍山石斛与其栽培土壤间的微量元素相关性比其它石斛强,因而可通过增施微肥的办法来提高霍山石解中某些人体必需微量元素的含量．     

金属离子螯合剂对橙汁中L—抗坏血酸的保护及其机理探讨

本文研究了在加热过程中金属离子螯合剂植酸、聚磷酸钠和EDTANa_2对橙汁和橙汁模拟体系中L—抗坏血酸的稳定作用,并采用红外光谱和紫外差光谱对EDTANa_2的保护机理作了初步探讨。结果表明:植酸和聚磷酸钠均不能降低Cu~(2+)对橙汁模拟体系中L—抗坏血酸氧化降解的催化作用,而EDTANa_2不仅能络合Cu~(2+),减少L—抗坏血酸的催化降解损失,而且红外光谱和紫外差光谱及溶剂微扰研究还揭示出EDTANa_2可与L—抗坏血酸形成氢键保护,这种氢键保护作用受到糖和柠檬酸的不利影响。     

盐酸胍诱导的α淀粉酶去折叠与再折叠

利用蛋白质内源荧光和酶活性两种信号以及荧光偏振,HPLC和停流等方法研究了盐酸胍诱导的α淀粉酶去折叠与重折叠的平衡转变和动力学。实验结果表明α淀粉酶去折叠与重折叠是两个不同的过程;变性与复性过程中可能伴有聚集体生成;去折叠与重折叠均为双相过程,重折叠大约始于2秒之后。     

鼎湖山自然林豆科固氮植物资源的调查研究

本文在调查鼎湖山自然林木本豆科植物结瘤固氮的基础上,参阅了国内外有关豆科植物结瘤固氮的主要文献,研究了鼎湖山自然林木本豆科植物的固氮资源。结果得出鼎湖山自然林中常见的木本豆科植物共有41种,其中乔木15种,灌木6种,木质藤本20种;有结瘤固氮特性的26种,其中乔木11种,灌木5种,木质藤本10种;经初步调查未见根瘤的6种,其中乔木2种,灌木1种,木质藤本3种;未调查的9种,其中乔木2种,木质藤本7种。本研究结果为鼎湖山木本豆科固氮植物资源的保护、管理和开发利用提供了科学论据,在理论和应用方面均有重要意义。     

Modulation of mechanosensitive calcium-selective cation channels by temperature

Gating of associations of mechanosensitive Ca²⁺-selective cation co-channels in the plasmalemma of onion epidermis has a strong and unusual temperature dependence. Tension-dependent activity rises steeply as temperature is lowered from 25°C to about 6°C, but drops to a low level at about 5°C. Under the conditions tested (with Mg²⁺ and K⁺ at the cytosolic face of outside-out membrane patches), promotion results both from more bursting at all observed linkage levels and from longer duration of bursts of co-channels linked as quadruplets and quintuplets. Co-channel conductance decreases linearly, but only modestly, with declining temperature. It is proposed that these and related mechanosensitive channels may participate in a variety of responses to temperature, including thermonasty, thermotropism, hydrotropism, and both cold damage and cold acclimation.     

Correlation between arrested secondary plasmodesmal development and onset of accelerated leaf senescence in yeast acid invertase transgenic tobacco plants

Mature leaves of a transgenic tobacco plant ( Nicotiana tabacum L var. Samsun, line A41-10) that constitutively express a yeast-derived acid invertase gene develop symptoms which are characterized by the presence of greenish-yellow and green sectors in the same leaf, and onset of early, leaf senescence. Previous studies indicated that invertase activity was two- to threefold higher in the greenish-yellow sectors than in the green sectors. Our structural analyses revealed that development of secondary plasmodesmata, via modification of existing primary plasmodesmata, between mesophyll cells was inhibited severely in the greenish-yellow sectors, but only marginally in the green sectors. In contrast, the structure and function of primary plasmodesmata in the same symptomatic sectors remained unaltered as determined by structural and dye coupling studies. It is hypothesized that secondary plasmodesmata differ from primary plasmodesmata in having special abilities to traffic information molecules to coordinate leaf development and physiological function(s). Arrest of secondary plasmodesmal development by high invertase activity in the transgenic tobacco leaf may have prevented this type of trafficking and hence resulted in early leaf senescence. The results also indicate that the yeast acid invertase-expressing tobacco may provide an effective experimental system for the molecular characterization of cellular mechanisms that regulate the development, function, and possible turnover of secondary plasmodesmata.     

蛋白质结构成对比较的新方法

介绍一种蛋白质三维结构的快速比较方法.此方法毋需初始联配,而能自动寻找和智能迭代.利用本程序对珠蛋白、丝氨酸蛋白酶、天冬氨酸蛋白酶、钙结合蛋白和溶菌酶作了系统的结构比较,取得了满意的结果.本文也讨论了衡量联配结果好坏的要素问题.     

蛋白质侧链的预测

根据Ｄｅｓｍｅｔ的死端排除定则制作了一种蛋白质侧链观测的快速软件系统,用一批实例结构数据和不同的侧链转子来检验上定则的可行性;并讨论预测的ＲＭＳ与溶剂可及性和结构元素的关系。