Selenium biochemistry

The toxicity of selenium to animals and plants has been known and extensively documented since the 1930's, but it is only during the past 15 years that selenium has also been shown to be an essential micronutrient for animals and bacteria. Very little is known about the specific role or roles of selenium and, to date, there are only three enzyme-catalyzed reactions that have been shown to require the participation of a selenium-containing protein. These are the reactions catalyzed by (i) formate dehydrogenase of bacteria, (ii) glycine reductase of clostridia, and (iii) glutathione peroxidase of erythrocytes. The common denominator of these selenium-dependent processes is that they are all oxidation-reduction reactions. A fourth selenoprotein has been isolated from skeletal muscle of sheep but its catalytic function has not been identified. The form in which selenium occurs in these selenoproteins is unknown. The selenoprotein of clostridial glycine reductase contains selenium in a covalently bound form. Studies in progress indicate that this may be an organoselenium compound not previously detected in nature. Identification of the chemical nature of selenium in proteins participating in electron transport processes should enable us to determine its specific role and to understand the basic defects in certain cardiac and skeletal muscle degenerative diseases which are selenium-deficiency syndromes. The greater availability and ease of isolation of the selenoprotein of the bacterial glycine reductase system makes this the biological material of choice for studies on the mechanism of action of selenium. An added attractive feature of this system is that it can conserve the energy made available by the reductive deamination of glycine in a biologically useful form by synthesizing ATP.     

生物化学精品课程建设的探索与实践

精品课程建设的实质是要将最新的科学技术引入教学课堂,打造出一批体现现代教育思想,符合科学性、先进性、具有鲜明特色,并能恰当运用现代教育技术、方法与手段,不仅教学效果显著,而且具有示范和辐射推广作用的精品课程。我校生物化学精品课程课题组按照“国家精品课程”建设内容和要求,根据高职高专培养目标和基本规格,以强化实践、培养高素质技能型人才为目的,在精品课程建设过程中进行了积极的探索与实践。     

嫁接对黄瓜土壤生化特性的影响

利用3室根箱栽培黄瓜自根苗(CK)、嫁接苗,研究2者根系分泌物对正茬土、连作土不同土层土壤微生物数量和酶活性的影响.结果表明,与对照相比,嫁接增加连作土与正茬土中微生物总量、细菌及放线茵数量,减少了真茵数量并增强了土壤中多酚氧化酶、过氧化氢酶、脲酶、蔗糖酶的活性;嫁接对距根表大于5 am的土层改善效果不明显.除此之外,嫁接对生茬土的效果明显好于连作土.试验结果说明,嫁接可以改变根表附近微生物种群数量和结构,增加有益茵数量,增强土壤酶活性,从而减轻设施黄瓜的连作障碍,嫁接对土壤不同土层的化感作用随着距根表的距离增加而减小.     

高职高专生物化学教学改革的探索

生物化学是高等农业院校的一门重要基础课程，又是学生普遍反映较难学好的一门课，如何让一年级学生克服畏惧心理，既愉快地学习，又培养对专业的兴趣，是笔者在近几年教学中一直思考与探索的问题。本文根据近几年的教学实践，对生化教学中的一些改革措施作简单的总结。     

对甘南牦牛血清生化指标的测定

牦牛Bos gruniens是世界上广大高寒草甸生态系统中的特殊家畜,能在其它牛种难以生存的高寒、低氧环境中健康生长和繁衍后代,在经过长期的自然选择和人工选育下,形成了许多优良的种群。关于牦牛血液生理生化指标方面的报道较多,如卢福山等对青海高原型牦牛、李莉等对互助牦牛、