还有"永生"的DNA链?(3)

DNA序列在一定程度上发生的改变既为生物的演化所必需,又是动物体内癌症发生、影响物种相对稳定存在的主要因素,它们之间必需要有一个平衡.在环境条件相对稳定的情况下,保持DNA序列的稳定对生物的生存更加重要.然而细胞分裂时DNA的复制过程不是100％准确,而是会有一定程度的误差,这是DNA序列发生变化的重要原因.为减少DN...     

"3S"技术在生态环境保护方面的应用

本文介绍了“3S”技术及其在环境质量评价、城市环境监测与管理、植被研究、土壤研究行生态环境保护方面应用的优势 ,并指出“3S”技术应用于生态环境保护的前景十分广阔。     

大白口蘑菌株"厦3"的分离驯化研究

采用菌柄组织分离,从野生大白口蘑获得菌株“厦3”,经转管驯化后,在适宜温度下,菌丝满管时间从32d左右缩短到15d左右。以棉籽壳基质的菌丝长速最快,沟叶结缕草基质次之,杂木屑基质最慢;经覆土袋栽,沟叶结缕草基质的生物效率（155.8%）高于木屑基质（80.1%）,增产94.5%。脱袋栽,在草料上的生物效率达123.9％。     

"生物技术实践"教学研讨(3)"植物组织培养"的教学组织

在“生物技术实践”模块课程标准中。植物组织培养的具体要求是“尝试植物的组织培养”。尝试是技能性目标中的模仿水平,即学生仿照教师的示范性动作完成对实验对象的操作。     

洋葱"昌激99-3"的激光诱变选育

采用CO2和He-Ne两种激光的三种剂量,分别辐照两个洋葱品种的湿种子,从He-Ne和CO2激光辐照元谋洋葱变异后代中选育出高产、优质、多抗、适应性较强的红皮洋新品种“昌激99-3”,经专家组实地验收亩产达9186.7Kg,是红皮洋葱经专家正式验收的全国最高产量。     

"3+大综合+1"中的生物教学初探

随着社会和经济的发展 ,特别是教育改革的深入 ,关于人才的培养和选择 ,目前已逐渐呈现出一种综合化、多样化的趋势。在培养人才和选拔人才方面 ,我国还存在着一些问题 ,如一方面国家急需创新和实践能力较强的人才 ,需要综合素质较高、知识面广、文理贯通的学生 ;另一方面传统的教育对人才培养和选择的单一化倾向 ,各学科彼此割裂、分离 ,教学和考试内容越来越深 ,学生的知识面越来越窄。具有调节未来人才智能结构功能的高考 ,为了适应形势发展的需要 ,在科目设置、考试内容、考试形式等方面正在逐步改革。河南省 2 0 0 1年高考实行“3+大综…     

"3+综合"——生物教学面临的机遇与挑战

今年浙江、江苏、山西、吉林 4省普通高校招生入学考试“3 X”科目设置采用“3 综合”形式 ,对于理科考生加考的“综合”为“理科综合”科目 ,它是由物理、化学和生物 3门学科组成的。生物学科与理、化相比有一个不同之处 ,它是在几年前被取消高考的科目。众所周知 ,由于高考指挥棒的作用 ,在中学 ,哪门学科不被列入高考科目 ,就会失去学校、学生以及家长的重视。其实 ,在近代从西方传入的各种学科中 ,生物学一开始就非常引人注目。当 2 1世纪即将到来的时候 ,生物学再次引起重视。随着世界人口的急剧增加 ,粮食危机日渐突出 ;同时人类生存…     

红皮洋葱"昌激99-3"的激光诱变选育

采用两种激光的三种剂量,分别辐照两个红皮洋葱品种的种子,从He-Ne和c02激光辐照云南元谋本地洋葱的变异后代中选育出高产、优质、多抗、适应性较强的红皮洋葱新品种“昌激99．3”,经专家组实地验收667m^2产量达9186．7kg,属红皮洋葱经专家正式验收的全国最高产量。     

小麦抗白粉病种质"91(260)3-3-8"的抗性鉴定及遗传分析

本试验对91（260）3-3-8对白粉病的抗性再次进行鉴定,进一步确定该材料对白粉病完全免疫。为了研究其抗白粉病基因的遗传规律,用感病材料陕225、小偃6、邯6172、豫麦49与该材料杂交得到F1、F2后代群体,发现F1抗白粉病;陕225／91（260）3-3-8F2、小偃6／91（260）3-3-8 F2、邯6172／91（260）3-3—8 F2群体抗感比例为3：1,表明“91（260）3—3—8”与感病材料陕225、小偃6、邯6172相比有1对抗白粉病基因的差异;豫麦49／91（260）3-3—8 F2群体抗感比例不完全符合3;1,其原因有待于进一步探明。     

关于"pH对酶活性的影响"3种实验方案的比较分析

关于"pH对酶活性的影响"的实验教学中,学生设计了3种不同的实验方案,在课堂交流研讨的过程中引起学生激烈的争论.现将这3种实验方案陈述如下,并将学生的争论进行了整理.     

《化石》99-3期"化石小测验"答案与揭晓

（一）答案（框图自上而下）中１框：类（联左５及右２）中２框：三叶虫类（联左３及右５）中３框：恐龙类（联左１及右１）中４框：菊石类（联左４及右３）中５框：海蕾类（联左２及右４）（二）获奖者名单：一等奖；段正东（４１２００５，湖南省株洲市光明玻璃集团包装分公司木箱车间）二等奖：（５名）蒋原（６５００９１，云南昆明市云南大学附属中学高一、二班）颜悦（４７６０００，河南商丘市梁园区西货场），高宽（２７２４００，山东省嘉祥县迎风路后山巷５号）马恩运（７３２８５０，甘肃兰州市５０８信箱甲５０号），何威（４…     

The synthesis of 3-amino-3-deoxy-α-d-glucopyranosyl α-d-glucopyranoside (3-amino-3-deoxy-α,α-trehalose

The preparation of 2,3-di-O-benzoyl-4,6-O-benzylidene-α-d-glucopyranosyl-2-O-benzoyl-4,6-O-benzylidene-α-d-ribo-hexopyranosid-3-ulose (3) from 4,6:4′,6′-di-O-benzylidene-α,α-trehalose (1) via the 2,3,2′-tribenzoate 2 has been improved. Reduction of 3 with sodium borohydride gave 2-O-benzoyl-4,6-O-benzylidene-α-d-allopyranosyl 2,3-di-O-benzoyl-4,6-O-benzylidene-α-d-glucopyranoside (4), which was converted into the methanesulfonate 5 and trifluoromethanesulfonate 6. Displacement of the sulfonic ester group in 6 with lithium azide was very facile and afforded a high yield of 3-azido-2-O-benzoyl-4,6-O-benzylidene-3-deoxy-α-d-glucopyranosyl 2,3-di-O-benzoyl-4,6-O-benzylidene-α-d-glycopyranoside (7), whereas similar displacement in 5 proceeded sluggishly, giving a lower yield of 7 together with an unsaturated disaccharide (8). The azido sugar 7 was converted by conventional reactions into the analogous 2,3,2′-triacetate 9, the corresponding 2,3,2′-triol 10, and deprotected 3-azido-3-deoxy-α-d-glucopyranosyl α-d-glucopyranoside (11). Hydrogenation of 11 over Adams' catalyst furnished crystalline 3-amino-3-deoxy-α,α-trehalose hydrochloride (12), the overall yield from 3 being 35%.     

Proteogenomic evidence for β-oxidation of plant-derived 3-phenylpropanoids in "Aromatoleum aromaticum" EbN1

The betaproteobacterium "Aromatoleum aromaticum" EbN1 utilizes eight different plant-derived nonhydroxylated (e.g. cinnamate) and hydroxylated (e.g. p-coumarate) 3-phenylpropanoids with nitrate as electron acceptor. Differential protein profiling (2D-DIGE) revealed abundance increases of five proteins (EbA5316 to EbA5320) during anaerobic growth with cinnamate, hydrocinnamate, p-coumarate, and 3-(4-hydroxyphenyl)propanoate, compared to anaerobic benzoate-adapted cells serving as reference state. The predicted functions of four of these proteins (EbA5317, fatty acid-coenzyme A (CoA) ligase; EbA5318, enoyl-CoA hydratase/isomerase; EbA5319, β-ketothiolase; and EbA5320, 3-hydroxyacyl-CoA dehydrogenase) suggest β-oxidation of the above 3-phenylpropanoids to benzoyl-CoA and p-hydroxybenzoyl-CoA, respectively. The fifth protein (EbA5316, ABC-type periplasmic solute-binding protein) could be involved in 3-phenylpropanoid uptake. The detection of 3-hydroxy-3-phenylpropanoate during anaerobic growth with cinnamate and hydrocinnamate or 3-hydroxy-3-(4-hydroxyphenyl)propanoate during anaerobic growth with p-coumarate and 3-(4-hydroxyphenyl)propanoate supports the proteome-predicted β-oxidation pathway. Based on the specific formation of EbA5316-20 also during anaerobic growth with further 3-phenylpropanoid growth substrates including cinnamyl alcohol, m-coumarate, 3-(3,4-dihydroxyphenyl)propanoate and 3,4-dihydroxycinnamate (caffeate), a common β-oxidation route is proposed for 3-phenylpropanoid degradation in strain EbN1. The low amount of metabolites attributable to cometabolic transformation of nongrowth supporting 3-phenylpropanoids (e.g. o-coumarate, ferulate) may be indicative for a high substrate specificity of the involved enzymes.     

"蛛丝马迹"之"马"

“蛛丝马迹”是人人皆知的成语 ,一般辞典的解释 ,“马迹”就是马经过后留下的痕迹或马脚印。蛛丝马迹比喻事情留下来的隐约可寻的痕迹和线索。可是 ,仔细推敲后发现 ,这样的解释是很难成立的。从事理来说 ,蛛丝是很不明显的 ,那么与之并列的马迹也应该是很不明显的 ,可是 ,作为家畜的马是个庞然大物 ,除了在水泥 ,柏油路上 ,它留下的脚印与痕迹应该是很明显的。蜘蛛的丝与高头大马的迹 ,可以说是风马牛不相及的 ,是很难放在一起相提并论的。从结构来说 ,很明显 ,这一成语中 ,“蛛丝”与“马迹”是并列的结构 ,“蛛丝”就是蛛的丝 ,是偏正关…     

"蚍蜉"非"匹夫"

你们好,我是《化石》这本书的小读,叫张野青,家住牛庄高中家属楼,在牛庄镇南关小学六年级一班读书,我觉得这本书很好。但我在2004年第一期上发现了错误,在《曾霸世界的巨鬣狗》这篇章中有一句话：‘与大象相争如匹夫撼树’中的‘匹夫’两字写错了,应该是‘蚍蜉’两字,这两字是当大蚂蚁讲的,意思是比喻力量很小而想动摇强大的事物,自不量力。这些也是我从字典中得到的,我想是原错了,应该改正。     

Do mitochondria act as "cargo boats" in the journey of GD3 to the nucleus during apoptosis?

Plasma membrane lipid rafts have been considered as a sort of "chamber", where several subcellular activities, including CD95/Fas-mediated pro-apoptotic signaling, can take place. Recently, we demonstrated that, after CD95/Fas triggering, raft-like microdomains could be detected in mitochondrial membranes. The mitochondrion appears as a dynamic and subcompartmentalized organelle in which microdomains might act as controllers of apoptosis-associated fission that results in the release of apoptogenic factors. Here, we hypothesize that some "small" mitochondria, possibly derived from their fission process, can reach the nuclear envelope and strictly interact with this. Mitochondria could act as a signaling "device" contributing to molecular trafficking of molecules, including raft-like components, during apoptosis.