古老铅锌矿山生态型东南景天对锌耐性及超积累特性的研究

植物长期生长在重金属污染的生境中,逐渐进化成不同的生态型.通过调查中国东南部古老Pb/Zn矿和非矿山生境中的植物种群,发现生长在古老Pb/Zn矿的东南景天(Sedum alfredii Hance)是一种新的Zn超积累植物.在自然和控制条件下,古老Pb/Zn矿生态型比非矿山生态型植株的茎粗、叶片大、植株高.在矿山土壤Zn有效含量为105.5～325.4 mg·kg-1时,矿山生态型东南景天植株地上部Zn含量为4134～5000 mg·     

太白山红桦林的初步研究

红桦(Betula albo-sinensis)林是太白山森林植被的重要类型,在山地植被垂直带谱中成为落叶阔叶林带的一个亚带,南坡分布于海拔1950—2650m,北坡分布于海拔2200—2750m。 太白山红桦林可分为7个类型： Ⅰ红桦+辽东栎林,Ⅱ红桦+辽东栎+华山松林,Ⅲ红桦 +华山松林,Ⅳ红桦纯林,Ⅴ红桦+华山松+牛皮桦林,Ⅵ红桦+牛皮桦+巴山冷杉林,Ⅶ红桦 +牛皮桦林。随着海拔高度的升高,红桦林各类型依次有规律的分布,但红桦始终占据优势地位,并有着相对稳定的结构组成。红桦林以高大粗壮的红桦个体为主,林内更新苗较少,天然更新状况普遍不良。优势种群(红桦)年龄分析表明,红桦种群为衰退种群。红桦种群的衰退特征反映出红桦林的消退发展趋势。 目前本区红桦林多属成熟林或过熟林,应加强人工更新。     

甘肃桦木属一新种

本文发表了甘肃桦木属一新种, 即肃南桦Betula sunanensis Y.J.Zhang sp.nov.     

PHYLOGENETIC VARIATION IN THE TOLERANCE AND UPTAKE OF ORGANIC CONTAMINANTS

An investigation into the phylogenetic variation of plant tolerance and the root and shoot uptake of organic contaminants was undertaken. The aim was to determine if particular families or genera were tolerant of, or accumulated organic pollutants. Data were collected from sixty-nine studies. The variation between experiments was accounted for using a residual maximum likelihood analysis to approximate means for individual taxa. A nested ANOVA was subsequently used to determine differences at a number of differing phylogenetic levels. Significant differences were observed at a number of phylogenetic levels for the tolerance to TPH, the root concentration factor and the shoot concentration factor. There was no correlation between the uptake of organic pollutants and that of heavy metals. The data indicate that plant phylogeny is an important influence on both the plant tolerance and uptake of organic pollutants. If this study can be expanded, such information can be used when designing plantings for phytoremediation or risk reduction during the restoration of contaminated sites.     

Cd AND Zn ACCUMULATION IN PLANTS FROM THE PADAENG ZINC MINE AREA

Significant cadmium (Cd) contamination In soil and rice has been discovered in Mae Sot, Tak province, Thailand where the rice-based agricultural systems are established in the vicinity of a zinc mine. The prolonged consumption of Cd contaminated rice has potential risks to public health and health impacts of Cd exposed populations in Mae Sot have been demonstrated. The Thai government has prohibited rice cultivation in the area as an effort to prevent further exposure. Phytoextraction, the use of plants to remove contaminants from soil, is a potential option to manage Cd–contaminated areas. However, successful phytoextraction depends on first identifying effective hyperaccumulator plants appropriate for local climatic conditions. Five sampling sites at Padaeng Zinc mine, Tak province were selected to collect plant and soil samples. Total Cd and Zn concentrations in sediments or soils were approximately 596 and 20,673 mg kg^?1 in tailing pond area, 543 and 20,272 mg kg^?1 in open pit area, 894 and 31,319 mg kg^?1 in stockpile area, 1,458 and 57,012 mg kg^?1 in forest area and 64 and 2,733 mg kg^?1 in Cd contaminated rice field. Among a total of 36 plant species from 16 families, four species (Chromolaena odoratum, Gynura pseudochina, Impatiens violaeflora and Justicia procumbens) could be considered as Cd hyperaccumulators since their shoot Cd concentrations exceeded 100 mg Cd kg^?1 dry mass and they showed a translocation factor > 1. Only Justicia procumbens could be considered as a Zn hyperaccumulator (Zn concentration in its shoot more than 10,000 mg Zn kg^?1 dry mass with the translocation factor > 1).     

Cd AND Zn TOLERANCE AND ACCUMULATION BY SEDUM JINIANUM IN EAST CHINA

Field survey, hydroponic culture, and pot experiments were carried out to examine and characterize cadmium (Cd) and zinc (Zn) uptake and accumulation by Sedum jinianum, a plant species native to China. Shoot Cd and Zn concentrations in S. jinianum growing on a lead/Zn mine area reached 103–478 and 4165–8349 mg kg^?1 (DM), respectively. The shoot Cd concentration increased with the increasing Cd supply, peaking at 5083 mg kg^?1 (DM) when grown in nutrient at a concentration of 100 μmol L^?1 for 32 d, and decreased as the solution concentration increased from 200 to 400 μmol L^?1. The shoot-to-root ratio of plant Cd concentrations was > 1 when grown in solution Cd concentrations ≤ 200 μmol L^?1. Foliar, stem, and root Zn concentrations increased linearly with the increasing Zn level from 1 to 9600 μmol L^?1. The Zn concentrations in various plant parts decreased in the order roots > stem > leaves, with maximum concentrations of 19.3, 33.8, and 46.1 g kg^?1 (DM), respectively, when plants were grown at 9600 μmol Zn L^?1 for 32 d. Shoot Cd concentrations reached 16.4 and 79.8 mg kg^?1 (DM) when plants were grown in the pots of soil with Cd levels of 2.4 mg kg^?1 and 9.2 mg kg^?1, respectively. At soil Zn levels of 619 and 4082 mg kg^?1, shoot Zn concentrations reached 1560 and 15,558 mg kg^?1 (DM), respectively. The results indicate that S. jinianum is a Cd hyperaccumulator with a high capacity to accumulate Zn in the shoots.     

广西区西南桦天然居群遗传多样性的研究

 以采自广西区11个西南桦(Betula alnoides)天然居群的种子培育出的幼苗为材料,取其嫩叶开展21种酶系统的水平切片淀粉凝胶电泳实验,运用作者改进的Tris-马来酸提取缓冲液 (含30%PVP 40 000和1%2-巯基乙醇),筛选出AMP(氨基肽酶Aminopeptidase)、FBA(果糖二磷酸酶Fructose-bisphosphate aldolase)、GDH(谷氨酸脱氢酶Glutamate dehydrogenase)、G6PD(6-磷酸葡萄糖脱氢酶Glucose-6-phosphate dehydrogenase)、IDH(异柠檬酸脱氢酶Isocitrate dehydrogenase)、MDH(苹果酸脱氢酶Malate dehydrogenase)、PGD(6-磷酸葡萄糖酸脱氢酶Phosphogluconate dehydrogenase)、PGI(磷酸葡萄糖异构酶Phosphoglucoisomerase)、PGM(磷酸葡萄糖变位酶Phosphoglucomutase)和SKD(莽草酸脱氢酶Shikimate dehydrogenase)等10种酶,获得了清晰且可重复的酶谱。通过谱带遗传分析确定了15个位点,其中有6个单态位点,9个多态位点 (0.95标准),具40个等位基因。在居群水平上,西南桦的多态位点百分数 (P) 为55.2%,平均每个位点的等位基因数 (A) 为2.00,平均预期杂合度 (He) 为0.204。均超过Hamrick (1992)等提出的远交风媒木本植物的平均值(53.0%,184%和0154),表明西南桦的遗传变异水平高。在11个西南桦居群内,实际杂合度 (Ho)均高于预期杂合度,出现杂合子过量,可能存在利于杂合子的自然选择。西南桦遗传多样性与地理位置相关不显著。居群2 (靖西地州)、5 (平果海城)、9 (田林者苗) 包含绝大部分的等位基因,而且具较高的遗传多样性,应加以保护和管理,作为其基因资源就地保存的基地。本研究解决了以西南桦嫩叶为材料进行等位酶分析的关键技术,为进一步开展西南桦乃至桦木属树种的遗传结构和遗传多样性等提供了技术基础;同时掌握了西南桦天然居群的遗传多样性现状,为其有效保护和合理经营以及西南桦的遗传改良提供了理论依据。     

Zinc Uptake into Synaptosomes

Zinc uptake was studied in synaptosomes, isolated by the Ficoll flotation technique, using the radiotracer 65Zn. True uptake of zinc could be discriminated from binding to the outside of the synaptosomes by the absence of accumulation at 0 degree C and the dependency of the rate of uptake on the medium osmolarity. The zinc uptake, studied in the presence of various zinc-complexing agents, showed saturation kinetics when analyzed in terms of [Zn]free, yielding Km = 0.25 microM. The zinc uptake was independent of both ATP and the Na+ gradient. No efflux of zinc could be demonstrated from preloaded synaptosomes due to the formation of insoluble zinc complexes inside the synaptosomes. The results are discussed in terms of the modulation of diverse neurochemical processes by zinc.     

锌及锌转运蛋白ZnT3在小鼠海马苔藓纤维的一致性分布

目的 研究游离锌离子和锌转运蛋白ZnT3在小鼠海马的定位以及二的分布是否具有一致性。方法 应用锌TSQ荧光技术、锌金属自显影技术检测含锌神经元内的游离锌离子;应用免疫电镜技术检测ZnT3在含锌神经元轴突终末的分布。结果 游离锌离子和ZnT3免疫反应产物的分布在海马苔藓纤维内的分布具有一致性。在齿状回和CA3区的苔藓纤维内,锌和ZnT3蛋白定位于轴突终末的突触小泡。富含锌离子的含锌神经元轴突终末与CA3区锥体细胞的胞体和树突形成突触。尚可见锌离子存在于突触间隙内。结论 ZnT3向突触小泡内转运锌离子使锌离子聚积在含锌神经元轴突终末的突触小泡内,发挥锌离子的神经生物学功能。     

氨基酰化酶中金属锌离子的功能作用

 氨基酰化酶是含锌金属酶。该酶每摩尔蛋白中含2摩尔Zn(Ⅱ)离子。金属鳌合剂与酶作用,通过竞争螯合Zn(Ⅱ)离子使酶活力下降。残余活力与残留金属含量呈正相关。竞争螯合的结果,生成不含金属的脱辅基酶蛋白,并导致酶活力的丧失。脱辅基酶由于加入Zn(Ⅱ)离子而恢复其活力。实验表明金属锌离子是氨基酰化酶催化活力所必需。与Zn(Ⅱ)离子相似,Co(Ⅱ)离子也可与脱辅基酶相结合并使之复活。 在190—240nm区域内对比了天然酶、脱辅基酶蛋白与Co(Ⅱ)置换氨基酰化酶的圆二色谱。远紫外圆二色谱表明,与天然酶相比,在脱辅基酶中由于金属离子的丧失导致主链构象发生变化,其中α螺旋增加约7％。因而锌离子(钴离子)对蛋白主链的反应最适构象有一定的稳定作用。脱辅基酶与Co(Ⅱ)离子结合,酶的主链构象恢复至与天然酶几近相同。可认为这是促使酶复活的内在因素。     

Zinc-induced alterations in contractile properties of rat diaphragm muscle in vitro

The effect of zinc ions on the isometric contraction of rat diaphragm muscles in the presence and in the absence of external calcium was studied. Using a transducer, the isometric force was measured as a function of supramaximal electrical stimulation, either directly or indirectly applied to the muscle. The following parameters were measured: peak twitch tension, PT, twitch contraction time, CT, relaxation half-time, RT-1/2, and peak rates of tension increase and decrease, +dP/dt and -dP/dt. The following zinc-induced alterations were observed: an increase of the PT; a decrease of the RT-1/2; an increase in the +dP/dt and -dP/dt. The CT was not changed significantly. Our results suggest that zinc ions have a positive inotropic effect on isolated diaphragm muscle. The increase in PT may be explained by a zinc-activated Ca²⁺ uptake by sarcoplasmic reticulum. This was followed by an increase in the rate of rise of tension development, which was secondary to increased -dP/dt. The mechanism(s) by which extracellular Ca²⁺ contributes to this action of zinc is not known.