Cloning and expressional analyses of a cinnamoyl CoA reductase cDNA from rice seedlings

Cinnamoyl CoA reductase (CCR: EC 1.2.1.44),the entry-point enzyme of the llgnin specific biosynthetic pathway, catalyzes the conversion of cinnamoyl CoA esters to their corresponding dnnamaldehydes. Multiple sequence alignment showed that the deduced polypeptide shared 70% similarity and 30% sequence identity at the amino acid level with defined CCR genes from other plant species and they all contain the common signature sequences thought to be the catalytic site as well as the putative NADP binding domain.Using a conserved OsCCR cDNA fragment as the probe for library screening, we isolated the genomic DNA that covered the whole coding region of OsCCR with total length of 3045bp including 4 introns and 5 exons. The open reading frame for our OsCCR gene coBtAin~ 337 amino adds. Northern blot indicated that OsCCR was expressed in different organs with the highest level found in stems. In situ hybridization results showed that OsCCR mRNA was localized mainly along the vascular bundles in stems and leaves, and also in lateral roots that was differentiating from the tiilering node. We conclude that the vascular-localized expression of OsCCR gene may suggest its possible involvement in llgnin biosynthesis. Cloning and characterization of OsCCR will help to clarify how llgniflcations in plants are regulated and will provide a physical basis for creating genetically engineered rice plants with optimal lignin contents.     

播娘蒿叶绿体型△12脱饱和酶的功能研究

本文应用RT-PCR和RACE方法扩增出了的播娘蒿叶绿体型△12脱饱和酶（Ds-FAD2CHL）全长cDNA,其完整编码框为1344 bp,编码447个氨基酸;该基因ORF在酵母Saccharamyces cerevisiae中的表达阐明其功能为将18:1^△9脱饱和生成亚油酸(18:2^△9,12);进一步切除叶绿体信号肽后的脱饱和酶在酵母中把18:1^△9脱饱和生成18:2^△9,12的效率提高了3.72%;通过GC/MS分析转基因酵母的磷脂及酰基辅酶A库发现,该脱饱和酶的作用底物为磷脂,而不是以酰基辅酶A形式结合的脂肪酸.     

The potential therapeutic role of statins in central nervous system autoimmune disorders

3-Hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins are widely used oral cholesterol-lowering drugs. Statins competitively inhibit HMG-CoA reductase, the enzyme that catalyzes conversion of HMG-CoA to L-mevalonate, a key intermediate in cholesterol synthesis. Certain metabolites of mevalonate are also involved in posttranslational modification of specific proteins involved in cell proliferation and differentiation. Thus, statins have important biologic effects that may be independent of their cholesterol-reducing properties. Recent studies indicate that statins have antiinflammatory and neuroprotective properties which may be beneficial in the treatment of multiple sclerosis as well as other central nervous system (CNS) neurodegenerative diseases. This article will outline current experimental evidence that may suggest potential clinical benefits for patients with CNS autoimmune disorders. Ultimately, clinical trials will have to determine the safety and efficacy of statins in this patient population.Received 17 April 2003; received after revision 21 May 2003; accepted 22 May 2003     

A signoidal relationship between liver stearoyl CoA desaturase activity and serum hormone concentrations caused by streptozocin and its antagonists

Summary Stearoyl CoA desaturase activity in liver microsomes, and insulin, thyroxine, and triiodothyronine levels in serum were measured after administration of streptozocin (STZ) and its antagonists to rats. The effect of STZ, which caused hyperglycemia and inhibited the desaturase activity, was antagonized by 2-desoxyglucose and 3-O-methyl-glucose; 1-O-methyl-3-desoxyglucose and 1-O-methyl-3-O-methylglucose were without any effect. The enzyme activity plotted against insulin levels showed a broad sigmoidal curve, whereas the activities versus thyroid hormone levels showed steeper sigmoidal curves.     

Acetyl-coenzyme A synthetase (AMP forming)

Acetyl-coenzyme A synthetase (AMP forming; Acs) is an enzyme whose activity is central to the metabolism of prokaryotic and eukaryotic cells. The physiological role of this enzyme is to activate acetate to acetyl-coenzyme A (Ac-CoA). The importance of Acs has been recognized for decades, since it provides the cell the two-carbon metabolite used in many anabolic and energy generation processes. In the last decade researchers have learned how carefully the cell monitors the synthesis and activity of this enzyme. In eukaryotes and prokaryotes, complex regulatory systems control acs gene expression as a function carbon flux, with a second layer of regulation exerted posttranslationally by the NAD⁺/sirtuin-dependent protein acetylation/deacetylation system. Recent structural work provides snapshots of the dramatic conformational changes Acs undergoes during catalysis. Future work on the regulation of acs gene expression will expand our understanding of metabolic integration, while structure/function studies will reveal more details of the function of this splendid molecular machine.Received 4 December 2003; received after revision 2 March 2004; accepted 16 March 2004     

酰基激酶和酰基CoA合成酶对螺旋霉素合成的影响

螺旋霉素链霉菌生物合成螺旋霉素的过程受许多酶的调控作用,酰基激酶和酰基CoA合成酶是螺旋霉素内酯环合成的重要酶,实验测定了它们的酶活趋势和酶的影响因子,结果表明,酰基激酶和酰基CoA合成酶都有两个活力峰,前者活性集中在发酵中前期,后者活性集中在发酵中后期,实验发现Co2 ,Mn2 对酰基激酶和酰基CoA合成酶有较强的激活作用,Cu2 对酰基激酶有抑制作用,但对酰基CoA合成酶有很强的激活作用,在发酵中期向摇瓶中补加二阶阳离子比在发酵初期加入有更明显的激活作用,平均效价最高提高了31％。     

胆汁酸教学改革体会

在生物化学胆汁酸教学过程中,关于胆汁酸命名,学生记忆不清晰.教学过程中对生成胆汁酸的原料乙酰辅酶A来源途径知识点进行系统的总结,并联系物质代谢中的糖代谢、脂类代谢、氨基酸代谢和核苷酸代谢.同时,归纳胆汁酸按来源和结构的全部命名,收到了很好的教学效果.     

关于移动IP中路由优化的研究

基本移动ＩＰ协议 (简称ＭＩＰ)迫使移动主机必须通过其主代理 (ｈｏｍｅａｇｅｎｔ)为所有的分组进行路由 ,从而产生“三角路由问题” ,如附图所示 .为解决该问题 ,我们给出了有关基本移动ＩＰ协议的扩展操作 ,使得在移动主机和对应通信节点之间可以不必通过主代理而进行路由 ,达到优化路由的作用 .这些扩展 ,称为路由优化操作 (简称ＲＯＭＩＰ) .附图　三角路由示意图1　路由优化技术概述1.1　基本思想路由优化的基本思想是 ,将隧道技术应用到发送分组的一般ＩＰ主机上 ,省去主代理的转发 ,最终解决“三角路由问题” .具体而言 ,当主代理…     

CoA产生菌的诱变育种及发酵条件研究

研究了ＣｏＡ产生菌诱变育种及摇瓶发酵条件。以产氨短杆菌（Ｂｒｅｖｉｂａｃ－ｔｅｒｉｕｍ ａｍｍｏｎｉａｇｅｎｅｓ）ＡＳ１．８４４为出发菌株， 经单菌落分离获得了 ＢＳ１．８４４菌株，再经过紫外和 ＮＴＧ诱变，获得了对 ＴＭＴＤ具有抗性的 ＣＴ４００变异株， ＣｏＡ产量为 ５３５ ｕ／ｍＬ，比原亲株提高了 ２６９％。实验了不同的培养基组分，获得了最适培养基。采用两步补料法能显著提高 ＣｏＡ产量，比原一步补料提高 ３３％。不加热提取工艺能有效降低色素含量， ＣｏＡ得率略有增加。实验选用了 ４种阳离子型表面活性剂，以 ＣＰＣ对积累 ＣＯＡ效果最好。