稀土对生物机体剂量效应机理的研究进展

综述了稀土元素对生物机体剂量效应的机理 ,从稀土对细胞质膜、细胞周期及细胞凋亡、Ca M水平调节的作用到对蛋白质、DNA的影响等不同层次和水平进行了探讨 ,以期为稀土在生物学领域的进一步广泛应用奠定理论基础     

稀土对藻类生物效应的研究进展

从藻类的生长状况和生理特性两个方面,总结近年来关于稀土对藻类生物效应的研究结果,目前研究表明,稀土对藻类的生物效应与稀土元素的种类和藻类的品种密切相关,因此进一步对更多的藻种开展研究是有意义的。现有的结论多是在实验室条件下得到,建议应充分涉及环境因素对该生物效应的影响及其规律,同时,进一步完善从细胞分子水平对该生物效应的认识。     

对稀土生物效应的细胞生物化学机制的评述

从细胞角度综述了稀土生物效应机理研究的现状。稀土与生物膜上的转运蛋白、受体蛋白及代谢蛋白、细胞质中的酶和细胞核中的遗传物质间都存在相对作用，表明了稀土对生物的作用是多途径的。同时，细胞核及核外区域对稀土存在不同的敏感浓度。在此基础上提出了稀土对微生物、植物和动物细胞共同作用的假想模型，并用该模型解释了稀土应用效果的稳定性、突发效应及稀土毒害诸问题。为稀土生物应用的理论研究与实践提供了新的思路。     

稀土生物效应研究进展

本文综述了稀土的生物效应 ,包括稀土的毒性 ,稀土在机体内的分布、运移 ,稀土对人或动物的致癌、致畸、致突以及稀土元素对蛋白质、酶的作用及影响等。     

稀土元素定位在生物体系中的应用

弄清稀土元素在细胞中作用的部位,对理解其生物效应具有极其重要的意义。同时,稀土元素本身具有一些特殊的化学性质,利用细胞定位技术,可以更有效地对生物系统研究。     

稀土的生物效应

稀土元素及其化合物具有特殊的性能和广泛的用途,因而近年来稀土的开发和利用有了很大发展。随着稀土在工业、农业、国防和医药学方面的广泛应用,研究稀土对环境和人体健康的影响巳成为一个急需解决的课题。我国稀土资源丰富,开发前景广阔,因此进行稀土的应用研究和生物效应研究都具有较大的现实意义。国外对稀土的生物效     

稀土微肥的远期生物效应实验初报

稀土元素及其化合物的毒性,在体内的代谢,毒理学作用已有广泛的研究和评述。为了配合稀土的农用实验,我们开展了稀土化合物对哺乳动物生长、生殖、致突变和致畸等远期生物效应的实验研究.本文报告的为其部份结果。     

稀土元素对Ca在细胞中分布影响机制的探讨

本文采用HPLC与ICP-AES联用及HPLC与ICP-MS联用的方法研究了细胞质膜上稀土元素与Ca的化学形态,同时还研究了土壤施加混合稀土对生物膜上Ca分布的影响.研究结果表明,稀土元素和Ca竞争膜磷脂上的结合位点,从而影响了膜上的Ca2+转运机制,导致了Ca在细胞中分布的改变.     

鸡饲料中添加稀土化合物效果研究

30年代后,国外学者对稀土元素的植物生理活性,曾作过一些研究。70年代以来.我国在稀土农用研究上有一系列突破,成功的将稀土应用于我国农业生产,为稀土的应用开辟了一个崭新的领域。配合稀土农用进行的稀土毒理学研究,曾发现一些稀土元素对动物有一定生理作用。80年代中后期陆续开始的稀土对畜禽鱼的作用研究,都取得了可喜进展。本文报道的是稀土化合物在鸡上的应用研究结果。5年来,通过小试、中试、示范     

农业废弃物吸附稀土离子的研究进展

稀土元素在工业上大量应用的同时, 给人类身体健康和生态环境带来了危害, 近年来引起了广泛关注.研究发现吸附法相比其他传统水处理方法具有效果较好、操作简单、成本较低等优点, 它是消除稀土离子危害的最具潜力的方法之一; 而农业废弃物吸附剂因是农业副产物具有廉价的特性, 且部分农业废弃物吸附稀土离子时吸附量大、反应速率快, 可作为主要研究对象.文中对农业废弃物吸附材料吸附稀土离子的机理、吸附影响因素、吸附应用与吸附模型研究进展进行总结评述, 并对农业废弃物吸附稀土离子的发展方向进行展望.      

Review, Intelligence and Development of Rare Earths during Biological Evolution

The relationship between organism and rare earth elements (REE) viewed from evolution was discussed.Some metal ions play key roles in biological functions, however, as the illustration in this article shows, with powerful affinities for oxygen and similar radius, REE can display equally or even more important functions in terms of its biological functions. These attractive characteristics have called more public attention and lead to many applications in agriculture, medicine fields, etc. Furthermore, the article employed the concept of entropy to discuss the dosage effect of REE on organism and the possibility whether REE can become a portion of organism during the evolution.     

Biological Function of REE in Plants & Microbes

Rare earth elements (REE) and their compounds are widely applied in agronomic and medical fields for many years. The bioinorganic chemical research of REE during the past few years indicates that REE play important roles in the promotion of photosynthetic rate as well as root absorption, regulation of hormone and nitrogen metabolism, and suppression of microbes, etc. The metallic or non-metallic targets of key biomolecule in various physiological processes can be chosen by REE for the chelation or replacement, which enables REE to regulate the biological functions or behaviors of those biomolecule and consequently leads to significant embodiment of biological function of REE in plants and microbes.Overdose of REE, however, shows an inhibitory effect on living organisms. Therefore, this paper proposes two suggestions that will be available in the extension of full use of REE's biological function. One is to obey the dose law of REE and control REE concentrations within a safe range. The other is to further test the bioaccumulation and long-period influence of REE on organisms.     

Intramembrane protein distribution in cell cultures is affected by 50 Hz pulsed magnetic fields

Intramembrane proteins (IMP) represent a class of proteins located in the lipid bilayer of the cell membrane which function as ion channels, enzymes or receptors. Since it has been argued that biological effects of extremely low frequency (ELF) electromagnetic fields are mediated by plasma membrane. this work was designed to study the possible effects of 50 Hz pulsed magnetic fields (PMF) of the type used to stimulate bone repair, on the distribution of IMP in the plasma membrane of Swiss NIH 3T3 fibroblasts. Evaluations were based on the calculation of a distribution factor, which allows discrimination between random, regular and clustered distribution of IMP, in electron microscope images of freeze-fractured membranes. The results indicate that cells exposed to PMF for more than two hours have a significant clustering of the IMP distribution compared to control unexposed cells.     

A/O活性污泥系统与生物膜系统处理炼焦工业废水对比试验研究

考察了在相同的运行条件下,A/O活性污泥系统和生物膜系统对炼焦工业废水的处理效果。试验结果表明,生物膜系统的抗冲击负荷能力强,处理效果优于A/O活性污泥系统,达到相同污染物去除率,生物膜系统的总水力停留时间缩短了7.5h,而且运行管理简单。     

Categorization of interictal epileptiform potentials using a graph-theoretic method

The properties, distribution, and biological functions of several proteases from the plasma membrane of lymphoid cells are reviewed: dipeptidyl peptidase IV, neutral endopeptidase, aminopeptidases A and N, and a new protease of the family of adamalysins. these enzymes (designated as ectopeptidases) are integral membrane proteins whose molecules are mainly located extracellularly. Their functions involve proteolysis on the cell surface: the formation and inactivation of regulatory peptides and growth factors, as well as modification of cell surface proteins. The biological significance of a partial proteolysis of the plasma membrane proteins and the resulting soluble isoforms are discussed. An analysis of the data suggests that ectopeptidases from lymphoid cells are elements of the sensory system of the cell and are involved in the regulation of its physiological response to external factors and in the coordination of cell-cell interactions.     

Stimulation of glucose transport in Clone 9 cells by insulin and thyroid hormone: role of GLUT-1 activation

Thyroid hormone (T3) and insulin are both shown to stimulate glucose transport in Clone 9 cells, a rat liver cell line in which the utilization of glucose is limited by transport rate and in which only the GLUT-1 transporter isoform is expressed. Pre-treatment of these cells with T3 moreover substantially enhances the stimulatory effect of insulin such that at maximally effective hormone concentrations the effects of T3 and insulin on glucose transport are more than additive and indeed nearly multiplicative, suggesting that the mechanisms mediating the enhancement of glucose transport differ between the two hormones. Cell surface biotinylation followed by Western-blot analysis of plasma membrane fractions showed that the stimulatory effects of T3 and insulin on glucose transport, whether acting singly or in combination, exceed the attendant increases in the abundance of GLUT-1 in the plasma membrane. It is suggested that activation of GLUT-1 molecules pre-existing in the plasma membrane plays a major role in mediating the stimulatory effects of T3 and insulin on glucose transport in this cell line.     

Effect of Rare Earths on Composition and Activities of Rare Earth Elements Binding Glycoprotein in Tea

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Redistribution of phosphatidylethanolamine at the cleavage furrow of dividing cells during cytokinesis

Ro09-0198 is a tetracyclic polypeptide of 19 amino acids that recognizes strictly the structure of phosphatidylethanolamine (PE) and forms a tight equimolar complex with PE on biological membranes. Using the cyclic peptide coupled with fluorescence-labeled streptavidin, we have analyzed the cell surface localization of PE in dividing Chinese hamster ovary cells. We found that PE was exposed on the cell surface specifically at the cleavage furrow during the late telophase of cytokinesis. PE was exposed on the cell surface only during the late telophase and no alteration in the distribution of the plasma membrane-bound cyclic peptide was observed during the cytokinesis, suggesting that the surface exposure of PE reflects the enhanced scrambling of PE at the cleavage furrow. Furthermore, cell surface immobilization of PE induced by adding the cyclic peptide coupled with streptavidin to prometaphase cells effectively blocked the cytokinesis at late telophase. The peptide-streptavidin complex treatment had no effect on furrowing, rearrangement of microtubules, and nuclear reconstitution, but specifically inhibited both actin filament disassembly at the cleavage furrow and subsequent membrane fusion. These results suggest that the redistribution of the plasma membrane phospholipids is a crucial step for cytokinesis and the cell surface PE may play a pivotal role in mediating a coordinate movement between the contractile ring and plasma membrane to achieve successful cell division.     

The PH domain and the polybasic c domain of cytohesin-1 cooperate specifically in plasma membrane association and cellular function

Recruitment of intracellular proteins to the plasma membrane is a commonly found requirement for the initiation of signal transduction events. The recently discovered pleckstrin homology (PH) domain, a structurally conserved element found in approximately 100 signaling proteins, has been implicated in this function, because some PH domains have been described to be involved in plasma membrane association. Furthermore, several PH domains bind to the phosphoinositides phosphatidylinositol-(4,5)-bisphosphate and phosphatidylinositol-(3,4,5)-trisphosphate in vitro, however, mostly with low affinity. It is unclear how such weak interactions can be responsible for observed membrane binding in vivo as well as the resulting biological phenomena. Here, we investigate the structural and functional requirements for membrane association of cytohesin-1, a recently discovered regulatory protein of T cell adhesion. We demonstrate that both the PH domain and the adjacent carboxyl-terminal polybasic sequence of cytohesin-1 (c domain) are necessary for plasma membrane association and biological function, namely interference with Jurkat cell adhesion to intercellular adhesion molecule 1. Biosensor measurements revealed that phosphatidylinositol-(3,4,5)-trisphosphate binds to the PH domain and c domain together with high affinity (100 nM), whereas the isolated PH domain has a substantially lower affinity (2-3 microM). The cooperativity of both elements appears specific, because a chimeric protein, consisting of the c domain of cytohesin-1 and the PH domain of the beta-adrenergic receptor kinase does not associate with membranes, nor does it inhibit adhesion. Moreover, replacement of the c domain of cytohesin-1 with a palmitoylation-isoprenylation motif partially restored the biological function, but the specific targeting to the plasma membrane was not retained. Thus we conclude that two elements of cytohesin-1, the PH domain and the c domain, are required and sufficient for membrane association. This appears to be a common mechanism for plasma membrane targeting of PH domains, because we observed a similar functional cooperativity of the PH domain of Bruton's tyrosine kinase with the adjacent Bruton's tyrosine kinase motif, a novel zinc-containing fold.