硅藻重金属污染生态学研究进展

硅藻是水生生态系统健康的指示生物之一,对环境变化极为敏感,某些典型硅藻已应用于指示水体重金属污染.本文围绕地表水重金属污染,从毒性效应、生物吸附和累积、生态适应机制及生物指示与生态修复作用等方面,综述了硅藻重金属污染生态学研究进展,阐述重金属污染下硅藻的生长趋势和硅壳形态的变化,硅藻对重金属生物吸附和生物累积的差别,硅藻对重金属的表面络合和离子交换等生态适应机制,以及硅藻对水体重金属污染的指示作用和生态修复作用,为水生生态系统的重金属污染防治与预警技术提供科学依据.     

海洋沉积物中重金属对底栖无脊椎动物的生物有效性

海洋沉积物是重金属的重要贮库,而海洋底栖无脊椎动物主要从沉积物中摄取重金属,这些被摄取的重金属能够通过食物链进行传递,进而影响到人类健康。本文总结了近些年来在海洋沉积物中重金属对底栖无脊椎动物生物有效性方面的研究进展,包括海洋底栖无脊椎动物对重金属的吸收途径、沉积物地球化学性质和底栖无脊椎动物生理等生物因素对沉积物中重金属生物有效性的影响。在此基础上,展望了未来研究重点,主要包括近海富营养化对沉积物中重金属生物有效性的影响,海洋底栖无脊椎动物消化道中的物理消化过程对沉积物中重金属生物有效性的影响,海洋底栖无脊椎动物整个生活史过程中沉积物中重金属生物有效性的变化等。     

植物重金属转运蛋白研究进展

土壤中的有毒重金属不仅对植物有害,也可通过食物链危害人类和动物的健康.重金属转运蛋白在植物吸收、抵抗重金属的复杂机制中起着关键作用.植物重金属转运蛋白分为吸收蛋白和排出蛋白,其中,吸收蛋白转运必需重金属进入细胞,同时也会因为必需重金属的缺乏或离子之间的竞争而运载有毒重金属;排出蛋白是一类解毒蛋白,可将过量的或有毒的重金属逆向转运出细胞,或区室化于液泡中.目前,细胞内多种重金属转运蛋白基因的转录水平与重金属离子积累之间的联系已被揭示,并分离克隆出诸多相关蛋白家族成员.本文综述了近年来发现并鉴定的主要重金属转运蛋白的金属亲和性、器官表达特异性及细胞内定位等的研究进展.     

Induction of nonmuscle myosin heavy chain II-C by butyrate in RAW 264.7 mouse macrophages

RAW 264.7 macrophages express nonmuscle myosin heavy chain II-A as the only significant nonmuscle myosin heavy chain isoform, with expression of nonmuscle myosin heavy chain II-B and II-C low or absent. Treatment of the cells with sodium butyrate, an inhibitor of histone deacetylase, led to the dose-dependent induction of nonmuscle myosin heavy chain II-C. Trichostatin A, another inhibitor of histone deacetylase, also induced nonmuscle myosin heavy chain II-C. Induction of nonmuscle myosin heavy chain II-C in response to these histone deacetylase inhibitors was attenuated by mithramycin, an inhibitor of Sp1 binding to GC-rich DNA sequences. Bacterial lipopolysaccharide alone had no effect on basal nonmuscle myosin heavy chain II-C expression, but attenuated butyrate-mediated induction of nonmuscle myosin heavy chain II-C. The effects of lipopolysaccharide were mimicked by the nitric oxide donors sodium nitroprusside and spermine NONOate, suggesting a role for nitric oxide in the lipopolysaccharide-mediated down-regulation of nonmuscle myosin heavy chain II-C induction. This was supported by experiments with the inducible nitric-oxide synthase inhibitor 1400W, which partially blocked the lipopolysaccharide-mediated attenuation of nonmuscle myosin heavy chain induction. 8-Bromo-cGMP had no effect on nonmuscle myosin heavy chain induction, consistent with a cGMP-independent mechanism for nitric oxide-mediated inhibition of nonmuscle myosin heavy chain II-C induction.     

红树植物抗重金属污染研究进展

综述了重金属污染对红树植物生长的影响,红树植物吸收重金属并在其体内分布以及在这种污染环境下红树植物可能存在的抗性机制。红树植物是通过根部吸收重金属的,进入其体内的重金属除少量分布在叶表面的各种腺体组织中外,主要富集在根部;对吸收到体内的重金属红树植物通过细胞壁沉淀,液泡的区域化等有效方式以降低其毒性;红树植物还可通过渗透作用把重金属排除到体外以减少对自身的毒害;另外,生长在此环境下的红树植物以增强自身抗氧化系统来加强其抗重金属的能力。对今后有关这方面的研究趋势提出了一些看法。     

Purification of messenger ribonucleic acids for fast and slow myosin heavy chains by indirect immunoprecipitation of polysomes from embryonic chick skeletal muscle

Fast and slow myosin heavy chain mRNAs were isolated by indirect immunoprecipitation of polysomes from 14-day-old embryonic chick leg muscle. The antibodies were prepared against myosin heavy chains purified by NaDod-SO4-polyacrylamide gel electrophoresis and were shown to be specific for fast and slow myosin heavy chains. The RNA fractions directed the synthesis of myosin heavy chains in a cell-free translation system from wheat germ. Several smaller peptides were also synthesized in lower concentrations. These probably are partial products of myosin heavy chains, since they are immunoprecipitated with antibodies to myosin heavy chains. Immunoprecipitation of the translation products with the antibodies to fast and slow myosin heavy chains showed the RNA preparations to be approximately 94% enriched for fast myosin heavy chain mRNA and approximately 84% enriched for slow myosin heavy chain mRNA with respect to myosin HC type. Peptides having slightly different mobilities on NaDodSO4-polyacrylamide gels were immunoprecipitated by antibodies to fast and slow myosin heavy chains.     

Phytochelatins and heavy metal tolerance

The induction and heavy metal binding properties of phytochelatins in heavy metal tolerant (Silene vulgaris) and sensitive (tomato) cell cultures, in water cultures of these plants and in Silene vulgaris grown on a medieval copper mining dump were investigated. Application of heavy metals to cell suspension cultures and whole plants of Silene vulgaris and tomato induces the formation of heavy metal–phytochelatin-complexes with Cu and Cd and the binding of Zn and Pb to lower molecular weight substances. The binding of heavy metal ions to phytochelatins seems to play only a transient role in the heavy metal detoxification, because the Cd- and Cu-complexes disappear in the roots of water cultures of Silene vulgaris between 7 and 14 days after heavy metal exposition. Free heavy metal ions were not detectable in the extracts of all investigated plants and cell cultures. Silene vulgaris plants grown under natural conditions on a mining dump synthesize low molecular weight heavy metal binding compounds only and show no complexation of heavy metal ions to phytochelatins. The induction of phytochelatins is a general answer of higher plants to heavy metal exposition, but only some of the heavy metal ions are able to form stable complexes with phytochelatins. The investigation of tolerant plants from the copper mining dump shows that phytochelatins are not responsible for the development of the heavy metal tolerant phenotypes.     

微生物与重金属间的相互作用及其应用研究

从多方面阐述了微生物与重金属二者间相互作用,指出微生物在生长代谢过程中能淋滤、吸收和转化重金属,对重金属有一定的抗性和解毒作用;但是,一定浓度的重金属对微生物过程及其种群具有较大的毒性。影响微生物在环境介质中的活动,矿业工程生产工艺已充分利用微生物能淋滤,吸收和转化重金属等特性来处理低品位难浸矿石,环境保护领域也积极利用微生物对重金属的抗性和解毒作用来实现工业废弃物的处理以及被重金属污染土壤的修复。利用微生物的生物量及其活性可以评价环境中不同介质的重金属污染水平。     

Glycosylation causes an apparent block in translation of immunoglobulin heavy chain

Analysis of nascent heavy chains isolated from MPC11 (gamma 2b heavy chains) and MOPC 21 (gamma 1 heavy chains) mouse myeloma cells demonstrates an accumulation of nascent heavy chains which are slightly smaller in mass (approximately 35,000 daltons) than nascent heavy chains which have just been glycosylated (approximately 38,000 daltons). The accumulation of 35,000-dalton nascent heavy chain appears to be a consequence of the glycosylation process since tunicamycin, an inhibitor of glycosylation, abolishes the apparent translational block manifested by the accumulation of 35,000-dalton nascent chains. Tunicamycin also causes a 15 to 25% increase n the relative rate of synthesis of heavy chain compared to the corresponding rate of synthesis of the nonglycosylated light chain synthesized by the same cell. These results suggest that the translation block, caused by the glycosylation process, of heavy chain synthesis contributes to the imbalance of heavy chain and light chain biosynthesis observed in malignant and normal lymphoid cells.     

Total concentrations and chemical speciation of heavy metals in liquefaction residues of sewage sludge

The risk (including bioavailability and eco-toxicity) of heavy metals (Pb, Zn, Cu, Cd, Cr and Ni) in liquefaction residues (LR) of sewage sludge (SS) was estimated, according to both the speciation of heavy metals and the local environmental characteristics. The amount of organic matters in LR was lower than that in SS, resulting in a smaller calorific value, while the total content of heavy metals in LR nearly doubled. High residual rates of heavy metals (about 80%) indicated that the heavy metals in SS were concentrated into LR after liquefaction. The comparisons of sequential extraction results between SS and LR showed that after liquefaction, the mobile and easily available heavy metal fractions (acid soluble/exchangeable and reducible fractions) were mainly transformed into the relatively stable heavy metal fractions (oxidizable and residual fractions). The bioavailability and eco-toxicity of heavy metals in LR were relieved, though the total concentrations of heavy metals increased.     

土壤重金属污染生态过程、效应及修复

本文探讨了重金属在土壤中的行为特性及其生态化学过程作用的特点,不同的重金属元素在土壤胶体颗粒表面的吸附特性及不同元素间的交互作用类型有所不同,自然对重金属迁移积累的影响有所不同。土壤重金属污染影响了种子萌发、幼苗生长、作物产量及体内重金属含量,探讨了污染土壤的酶学评价方法。阐述了重金属污染土壤生物修复的特点,展望了重金属污染生态过程研究的未来发展趋势。     

高等植物重金属耐性与超积累特性及其分子机理研究

由于重金属污染日益严重, 重金属在土壤_植物系统中的行为引起了人们的高度重视。高等植物对重金 属的耐性与积累性, 已经成为污染生态学研究的热点。近年来, 由于分子生态学等学科的发展, 有关植物对重金属的解毒和耐性机理、重金属离子富集机制的研究取得了较大进展。高等植物对重金属的耐性和积累在种间和基因型之间存在很大差异。根系是重金 属等土壤污染物进入植物的门户。根系分泌物改变重金属的生物有效性和毒性, 并在植物吸收重金属的过程中发挥重要作用。土壤中的大部分重金属离子都是通过金属转运蛋白进入根细胞, 并在植物体内进一步转运至液泡贮存。在重金属胁迫条件下植物螯合肽 (PC) 的合成是植物对胁迫的一种适应性反应。耐性基因型合成较多的PC, 谷胱甘肽 (GSH) 是合成PC的前体, 重金属与PC螯合并转移至液泡中贮存, 从而达到解毒效果。金属硫蛋白 (MTs) 与PC一样, 可以与重金属离子螯合, 从而降低重金属离子的毒性。该文从分子水平上论述了根系分泌物、金属转运蛋白、MTs、PC、GSH在重金属耐性及超积累性中的作用, 评述了近 10年来这方面的研究进展, 并在此基础上提出存在的问题和今后研究的重点。     

Further studies on the interaction of actin with heavy meromyosin and subfragment 1 in the presence of ATP.

It has been postulated that, during the hydrolysis of ATP, both normal and SH1-blocked heavy meromyosin undergo a rate-limiting transition from a refractory state which cannot bind to actin to a nonrefractory state which can bind to actin. This model leads to several predictions which were studied in the present work. First, the fraction of heavy meromysin or subfragment 1 which remains unbound to actin when the ATPase equals Vmax should have the same properties as the original protein. In the present study it was determined that the unbound protein has normal ATPase activity which suggests that it is unbound to actin for a kinetic reason rather than because it is a permanently altered form of the myosin. Second, if the heavy meromyosin heads act independently half as much subfragment 1 as heavy meromyosin should bind to actin. Experiments in the ultracentrifuge demonstrate that about half as much subfragment 1 as heavy meromyosin sediments with the actin at Vmax. Third, the ATP turnover rate per actin monomer at infinite heavy meromyosin concentration should be much higher than the ATP turnover rate per heavy meromyosin head at infinite actin concentration. This was found to be the case for SH1-blocked heavy meromyosin since, even at very high concentrations of SH1-blocked heavy meromyosin, in the presence of a fixed actin concentration, the actin-activated ATPase rate remained proportional to the SH1-blocked heavy meromyosin concentration. All of these results tend to confirm the refractory state model for both SH1-blocked heavy meromyosin and unmodified heavy meromyosin and subfragment 1. However, the nature of the small amount of heavy meromyosin which does bind to actin in the presence of ATP at high actin concentration remains unclear.     

Advances in Cotton Tolerance to Heavy Metal Stress and Applications to Remediate Heavy Metal-Contaminated Farmland Soil

Heavy metal-contaminated soil is one of the major environmental pollution problems of agricultural production and human health in the world. Remediation of heavy metals in soil is one of the most popular research subjects. Different remediation strategies have been reported to remove heavy metals from contaminated soil, among which phytoremediation is the most important one. Compared with other major crops, cotton shows the strongest and most widespread resistance to abiotic stresses, such as heavy metals. Although heavy metal stress adversely affects the growth and development of cotton, cotton possesses a set of sophisticated stress-resistance strategies. As the main product of cotton is nonedible fibers, which have a large biomass and strong heavy metal absorption and enrichment capacities, cotton is an ideal crop to restore heavy metal-contaminated soils and has unique advantages in terms of both ecological and economic benefits, with great application prospects. In this review, based on domestic and foreign research results in recent years, the effects of heavy metals on cotton growth and product quality were analyzed, the heavy metal absorption, accumulation, translocation and enrichment characteristics of cotton plants were summarized, and the adaptation and tolerance mechanisms of cotton to heavy metals were explored. Furthermore, the view that cotton is an effective crop to remediate heavy metal pollution in farmland soil has been proposed, and popularization and application suggestions for planting cotton to repair heavy metal pollution have been put forward to provide a reference for the comprehensive evaluation of the economic feasibility of cotton to repair heavy metal pollution in farmland soil.     

土壤重金属生物毒性研究进展

世界范围内土壤重金属污染不断加重,由污染所带来的问题以及如何治理污染已经受到人们越来越多的关注.土壤重金属将对土壤生物产生影响,而土壤生物在重金属的胁迫下也会产生不同的响应.综述了国内外近年来土壤重金属生物毒性的研究进展,介绍了土壤重金属污染对陆地生态系统中植物、动物和微生物生长的影响;土壤重金属生物毒性的影响因素;土壤重金属生物毒性的研究方法;土壤重金属生物毒性的预测模型,最后提出了问题和展望.     

胶州湾海水,海洋生物体中重金属含量的研究

研究了胶州湾海水、海洋生物体中重金属含量 .结果表明 ,沿岸河口地区海水中重金属污染主要受沿岸工业排放废水的影响 ;海洋生物体内重金属含量不仅受海水中的重金属含量大小的支配 ,温度对其也有一定的影响 .海洋生物体中重金属含量为底栖生物大于鱼类 ,以沉积物为主要饵料的杂食性底栖动物内重金属含量大于鱼类 ;海洋生物对于Cu比其它重金属具有较强的富集能力 .     

Removal of heavy metals by an enriched consortium

An enriched consortium obtained from lake-sediment was developed for the removal of heavy metals such as Cu, Pb, Cr, Ni, and Zn from heavy metal-contaminated water. The removal efficiency of heavy metals in a shaking condition was generally higher than that in the static state. After the fifteenth enrichment with assorted heavy metals, the removal efficiencies in the shaking and static condition at an average concentration of 100 mg/L of each heavy metal were approximately 99 approximately 100% and 95 approximately 100%, respectively, depending on the type of heavy metal. An aerobically grown, pure culture isolated from an enriched culture was analyzed by 16S rRNA sequencing and identified as Ralstonia sp. HM-1. This strain was found to remove various heavy metals with an efficiency of approximately 97 approximately 100% at an average concentration of 200 mg/L of each heavy metal.     

胶州湾海水、海洋生物体中重金属含量的研究

研究了胶州湾海水、海洋生物体中重金属含量.结果表明,沿岸河口地区海水中重金属污染主要受沿岸工业排放废水的影响;海洋生物体内重金属含量不仅受海水中的重金属含量大小的支配,温度对其也有一定的影响.海洋生物体中重金属含量为底栖生物大于鱼类,以沉积物为主要饵料的杂食性底栖动物内重金属含量大于鱼类;海洋生物对于Cu比其它重金属具有较强的富集能力.     

矿质元素互作及重金属污染的研究进展

随着工农业的发展,重金属污染问题在我国越来越严重。矿质元素互作的研究是理解重金属植物体内迁移规律,解决矿质营养利用和重金属污染治理的矛盾以及重金属复合污染问题的必然要求。本文从几个与重金属关系密切的矿质元素入手,并结合离子组学的发展,简要介绍了矿质元素与重金属的互作方面的主要进展,并对解决重金属污染和重金属复合污染问题进行了探讨。     

Thyroid hormone stimulates synthesis of a cardiac myosin isozyme. Comparison of the two-two-dimensional electrophoretic patterns of the cyanogen bromide peptides of cardiac myosin heavy chains from euthyroid and thyrotoxic rabbits.

The CNBr peptides of [14C]carboxymethylated cardiac myosin heavy chains from euthyroid and thyrotoxic rabbits have been compared using a two-dimensional electrophoretic system. The results indicated that there were extensive differences in the peptide "maps" of these heavy chains, which included differences in the distribution of radiolabeled thiol peptides. Also, the patterns of heavy chain peptides from the cardiac myosins have been compared with those produced by the heavy chain myosin isozymes from skeletal muscles. Peptide maps of heavy chains from red skeletal muscle myosin closely resembled the pattern of peptides found with cardiac myosin heavy chains from euthyroid rabbits. However, peptide maps of heavy chains from white skeletal muscle myosin were dissimilar to those of the cardiac myosin isozymes. We conclude that thyroxine administration stimulates the synthesis of a cardiac myosin isozyme with a heavy chain primary structure which is different from either of the skeletal muscle myosin isozymes.