植物维生素E基因工程研究进展

维生素E(vitamin E)是一种脂溶性维生素,是生物体内最主要的抗氧化剂之一。本文综述了植物维生素E的合成途径及所涉及的相关基因,针对提高植物中维生素E含量的基因工程改造,提出三条途径,即提高代谢底物水平、提高植物生育酚总量和提高α 生育酚比例,分析了维生素E基因工程改造过程中需要考虑的因素,最后展望了未来作物维生素E的品质改良的研究方向。     

提高植物维生素含量的基因工程

维生素是维持生物正常生长发育必需的一大类微量营养物。对利用基因工程的方法提高植物中维生素A、E和C含量的研究进展作了综述 ,指出了该类研究的一般方法并对未来做了展望。     

植物维生素E合成及其生物技术改良

维生素E是一种抗氧化剂 ,对植物、动物和人类自身都具有十分重要的作用 ,而植物则是人类维生素E的主要来源 ,因此克隆植物中维生素E合成的相关酶基因 ,对维生素E含量进行改良 ,具有重要意义。对植物中维生素E的合成途径 ,相关酶基因的克隆以及用生物技术的方法对维生素E含量进行遗传改良进行了综述。     

植物内源维生素E的抗氧化作用

所有需氧生物都必须依赖氧才能获得能量和维持生命,然而氧对所有需氧生物又都具毒害作用。近年来,生物氧代谢研究领域十分活跃,尤其是关于活性氧类物质在生物体内的产生及其清除的研究,积累了许多资料,使人们对氧毒害有了进一步的认识。     

植物维生素E基因工程研究进展

维生素E(vitamin E, VE)是一类由光合生物合成的、人类饮食中必不可少的两种抗氧化物质,分为生育酚和生育三烯酚两大类。除了生育酚类物质所具有的抗氧化作用外,生育三烯酚还有很强的降胆固醇、预防糖尿病、促进骨吸收、抗癌和神经保护的作用,因此,VE被广泛应用于医药、食品、化妆品等行业中。本文主要综述了植物维生素E生物合成相关酶的研究进展以及利用基因工程手段提高植物维生素E活性的新策略。其中,多基因共转化、多基因操纵子及质体转化等方法为提高植物维生素E活性提供了新的思路。     

天然维生素E的生物合成途径

概述了近些年来维生素E生物合成途径及其调控的研究进展.     

天然维生素E异构体中α生育酚的气相色谱分析

本文报道了气相色谱法测定天然VE中α生育酚的含量,以三甲基对苯二酚为标样,邻苯二甲酸二甲酯为内标物,5%SE-30色谱柱,RSD为1.1%-1.3%(n=5)。回收率为94.6%-96.2%。     

植物抗病毒基因工程

植物病毒病难以防治已成为植物界的"癌症",给全球农业生产造成巨大的损失。有效地防治植物病毒病,减少经济损失,满足日益增长的世界人口需求。是农业生产当务之急。病毒分子生物学,植物基因工程的迅速发展,为筛选培育抗病、优质、丰产的新植物开辟了广阔的前景。自1986年,全球范围内兴起了多种利用分子生物学及基因工程研究成果防治植物病毒病害的策略,并成功地培育筛选出多种抗病毒的工程植物。1病毒外壳蛋白介导的基因工程抗病性外壳蛋白是形成病毒颗粒的结构蛋白,它的功能是将病毒基因组核酸包被起来,保护核酸;与宿主互相识别…     

天然维生素E的研究进展

维生素E是一类脂溶性、具抗氧化功能的维生素,按其来源可分为天然维生素E和人工合成维生素E.对天然维生素E的功能、生物合成途径以及相关酶基因的研究方面进行了综述.其中,维生素E合成相关酶基因已经克隆及定位,尤其VTE5的发现,为生育酚合成研究开辟了一条新途径.人们已经开始利用基因工程技术研究提高植物天然维生素E产量的方法.     

维生素E琥珀酸酯的合成及表征

目的:合成维生素E琥珀酸酯并对其进行表征.方法:以d,1-α-生育酚和丁二酸酐为原料,吡啶为溶媒,合成了维生素E琥珀酸酯.采用紫外光谱法、红外光谱法、核磁共振氢谱和差示扫描量热分析对产物进行表征.结果:经验证,成功合成了维生素E琥珀酸酯.结论:成功合成了维生素E琥珀酸酯.     

Recent developments in vitamin E nutrition of turkeys

Research and field observations have shown that vitamin E status of poults is often inadequate during the 5 to 21-day posthatching period. Although overt consequences of this inadequacy may not be evident and clear-cut, subtle adverse effects on health and metabolic efficiency are probable. These latter effects can result in uneconomical performance of turkeys. It therefore seems advisable to supplement the first diet (starter or prestarter) of poults with 100 to 150 IU of vitamin E. The cost of doing so will contribute little to the total cost of production and may facilitate more efficient turkey production. In the meantime, other alternatives that may be effective and economical need to be evaluated.     

基因工程植物的安全性问题

转基因植物的研究进展很迅速,但基因工程植物是否安全一直争论不休,主要表现在转基因食品的安全性及生态安全性问题上.转基因食品的安全性涉及这些食品的过敏性、毒性以及抗生素标记基因的安全性几个方面.转基因植物的生态安全性包括基因漂流、是否能诱发昆虫产生Bt抗性和对生物多样性的影响等.本文针对这些问题,对转基因植物潜在危害以及国际上现有的评价作简要综述.     

The molecular basis of vitamin E retention: structure of human alpha-tocopherol transfer protein

Alpha-tocopherol transfer protein (alpha-TTP) is a liver protein responsible for the selective retention of alpha-tocopherol from dietary vitamin E, which is a mixture of alpha, beta, gamma, and delta-tocopherols and the corresponding tocotrienols. The alpha-TTP-mediated transfer of alpha-tocopherol into nascent VLDL is the major determinant of plasma alpha-tocopherol levels in humans. Mutations in the alpha-TTP gene have been detected in patients suffering from low plasma alpha-tocopherol and ataxia with isolated vitamin E deficiency (AVED). The crystal structure of alpha-TTP reveals two conformations. In its closed tocopherol-charged form, a mobile helical surface segment seals the hydrophobic binding pocket. In the presence of detergents, an open conformation is observed, which probably represents the membrane-bound form. The selectivity of alpha-TTP for RRR-alpha-tocopherol is explained from the van der Waals contacts occurring in the lipid-binding pocket. Mapping the known mutations leading to AVED onto the crystal structure shows that no mutations occur directly in the binding pocket.     

Progress of vitamin E metabolic engineering in plants

Vitamin E is important for human and animal health. Many human diseases, such as certain cancers and neurodegenerative and cardiovascular disease, are associated with the insufficient intake of vitamin E. The daily requirements for vitamin E in men and women have been increased to 15–30 mg. Because the primary source of dietary vitamin E comes from plants, there is a need to increase vitamin E production through plant engineering in order to meet the demand in human consumption. Numerous studies have been carried out in this field, leading to many successful examples. In this review, we summarized the recent progress in vitamin E metabolic engineering in plants aimed at improving the vitamin E content and regulating composition of vitamin E.     

植物抗寒基因工程研究进展

本评述了近年来有关植物抗寒生理及分子生物学方面的研究进展,对冷诱导基因的功能,诱导调控以及抗寒转基因策略等做一总结。     

植物代谢工程的研究现状

植物代谢工程是一个很有发展前景的新兴学科。它可通过多种方法对植物的代谢流进行改造,如加速限制步骤的反应,改变分叉代谢途径的流向,构建代谢旁路,引入转录调节因子、信号因子、植物激素合成基因,扩展和构建新的代谢途径等方法进行。并取得了一些有意义的研究结果。     

Inter- and intra-individual variation in plasma and red blood cell vitamin E after supplementation

To establish the range of individual blood responses to supplemental vitamin E, 30 healthy subjects ingested 75 mg of deuterium-labelled α-tocopherol with a standard breakfast. Blood was collected at 6, 9, 12, 27 and 51 h post ingestion and deuterated (d₆) and non-deuterated (d₀) α-tocopherol concentrations were determined in plasma and red blood cells (RBC) by GC-MS. To examine intra-individual responses, 6 of these subjects were re-examined at 6-month intervals over a 30-month period. Post ingestion, the amount of d₆-α-tocopherol in blood increased rapidly with time with maximal concentrations seen at 12 h (plasma) and 27 h (RBC) in most subjects. At these times, d₆-α-tocopherol concentration ranged from 0.3–12.4 μmol/l in plasma and 0.6–4.09 μmol/l packed cell in RBC. Area under the curve calculations indicated inter-individual differences of α-tocopherol uptake to be 40-fold for plasma (12.9–493.3 μmol h/l) and 6-fold for RBC (24.4–146.1 μmol h/l packed RBC). Intra-individual variation in α-tocopherol uptake was small in comparison and remained relatively constant over the 30-month period. We conclude that vitamin E uptake varies widely in the normal population, although it is comparatively stable for an individual over time. These differences likely arise from variations in the regulation of vitamin E uptake and metabolism between subjects. Factors regulating this process must be better understood before the optimal intake of vitamin E can be ascertained.     

Biological functions and metabolic fate of vitamin E revisited

Information accumulated lately has confirmed the essentiality of vitamin E for humans and provided a better understanding of its biological function and metabolic fate. The discovery of -tocopherol transfer protein, which preferentially binds to RRR--tocopherol, not only provides conclusive evidence of the essentiality of vitamin E for humans, but also sheds light on the superiority of RRR--tocopherol biologically over other isomers. The presence of tocopherol regeneration systems and multiple interdependent antioxidant systems is largely responsible for the lack of a widespread deficiency in humans and the difficulty to deplete vitamin E in the adult. The bulk of excess tocopherols consumed is excreted to feces unchanged or to urine with the side chain shortened but the chroman ring intact. The ability of dietary vitamin E to mediate mitochondrial superoxide generation affords a possible mode of action of vitamin E at the tissue levels. By decreasing the generation and/or the levels of reactive oxygen/nitrogen species, dietary vitamin E not only protects against oxidative damage, but also modulates the expression and/or activation of redox-sensitive biological response modifiers that regulate important cellular events.