Cd2+对二化螟生长发育及雄蛾对性信息素定向行为的影响

本文采用室内添加含6个不同浓度Cd~(2+)[0(对照)、1 mg/kg、5 mg/kg、10 mg/kg、15 mg/kg、20 mg/kg]的人工饲料的方法饲养二化螟Chilo suppressalis(Walker)2龄幼虫,测定二化螟的生长发育和雄蛾对性信息素的定向行为,研究稻田重金属镉(Cd~(2+))污染对二化螟生长发育及定向行为的潜在影响。结果表明:二化螟的生长发育和雄蛾对性信息素定向反应率受到了Cd~(2+)的影响。其中取食含Cd~(2+)人工饲料后,二化螟幼虫历期延长3.4-21.9 d,蛹历期缩短0-2.3 d,化蛹率及羽化率分别降低1.9%-35.7%和13.6%-44.9%;低浓度Cd~(2+)(1-10 mg/kg)处理后雌、雄蛹重分别增重4.3-4.8 mg和0.8-3.8 mg,高浓度Cd~(2+)(15-20 mg/kg)处理后雌、雄蛹重分别减轻0.2 mg和5.2 mg;高浓度Cd~(2+)处理的雄蛾接近正常求偶雌蛾的百分率低于它们接近Cd~(2+)处理后求偶雌蛾的百分率,而低浓度Cd~(2+)雄蛾接近正常雌蛾、Cd~(2+)雌蛾的百分率与对照组无显著差异。另外,正常雄蛾接近Cd~(2+)处理后求偶雌蛾的百分率未受显著影响。     

一株虾池来源的螺旋拟柱孢藻藻株的分离鉴定及重金属离子Cu~(2+)、Cd~(2+)和Pb~(2+)对其生长的影响

【目的】探讨凡纳滨对虾养殖水体中入侵蓝藻拟柱孢藻的生长生理特性。【方法】从汕头澄海人工对虾养殖池分离纯化藻株,通过形态及其16SrRNA基因鉴定,之后在CT与BG11两种蓝藻通用培养基的基础上优化最佳培养条件,最后分析了不同浓度的3种重金属离子即Cu~(2+)(0–0.8 mg/L)、Cd~(2+)(0–4 mg/L)和Pb~(2+)(0–80 mg/L)对藻株生长的影响。【结果】澄海虾池来源的分离纯化藻株形态呈卷曲螺旋型,16S rRNA基因序列与多株其他来源的拟柱孢藻相似度均达98%以上。实验室培养,藻株最佳生长状态的培养条件是在BG11培养基的基础上调整氮浓度及氮磷比分别为N 62 mg/L,N︰P=9︰1,在此条件下,藻丝生物量可达(0.632±0.170)×107/L,藻丝比平均生长速率最高为(0.063±0.001)/d。本分离藻株活体对重金属Cu~(2+)、Cd~(2+)和Pb~(2+)具有一定的耐受性,其耐受浓度范围分别为0–0.2、0–0.5和1–40 mg/L,其中,Cu~(2+)和Cd~(2+)对藻的生长具有抑制作用,而且此抑制作用随着金属离子剂量的增加及作用时间的延长更加显著,Cu~(2+)和Cd~(2+)对藻体的半数抑制浓度(96 h EC50)分别为0.125和0.551 mg/L;而浓度范围为0–80 mg/L的Pb~(2+)对藻体的生长则表现为低剂量(≤40 mg/L)呈促进,高剂量(≥80 mg/L)则抑制。【结论】从凡纳滨对虾养殖池中分离鉴定出一株形态呈螺旋型的拟柱孢藻,命名为螺旋拟柱孢藻(Cylindrospermopsis raciborskii helix),本藻株活体能够在一定浓度的Cu~(2+)、Cd~(2+)和Pb~(2+)中生长,为螺旋拟柱孢藻活藻生物吸附重金属离子而改善虾池水体环境提供了可能性。     

紫花苜蓿对铜胁迫生理响应的傅里叶变换红外光谱法研究

为阐明紫花苜蓿(Medicago sativa L.)对铜胁迫的耐性机理,采用准确度好、分辨率高和简便快捷的傅里叶变换红外光谱法(FTIR)研究在不同铜浓度(0、1、5、20、100 mol/L)处理时紫花苜蓿根、茎、叶化学组分的变化。结果表明:随着铜处理浓度的增加,紫花苜蓿根、茎、叶生物量变化不大。其根组织在2924 cm~(-1)处峰高处呈现出先下降后上升的趋势,反映了在低铜(5 mol/L)处理条件下紫花苜蓿分泌的有机酸不断螯合Cu,造成羧酸0-H的减少,但随着Cu含量的升高,其羧酸螯合力变弱,有机酸含量渐渐升高;根组织在1381 cm~(-1)处峰高先下降后上升,反映了含油脂化合物含量先下降后升高。可能与植物在细胞壁结构上增强抗逆性有一定关系,即低Cu处理下细胞壁可能通过提高阳离子交换能力(CEC),增强了耐Cu性;茎组织在2924,1643,1381,1064 cm~(-1)等处峰高无明显变化;叶组织所有峰值在低浓度(5 mol/L)Cu处理下变化不明显,高浓度(5 moL/L)Cu处理下所有峰值先升后降,随着这可能与可溶性糖及可溶性蛋白质等物质含量都呈现先升后降的趋势有关。这表明紫花苜蓿通过根部有机酸含量的变化和提高细胞壁阳离子交换能力,将吸收的Cu大部分积累在根部,阻止Cu向地上部分运输,有效地保护了植物地上部分组织。     

镉在土壤-香根草系统中的迁移及转化特征

以无植物组处理为对照,采用盆栽试验方式探讨不同Cd浓度胁迫条件下香根草根际土壤中重金属Cd的积累、迁移及转化特征。土壤Cd处理设4个浓度梯度,分别为0、2、20、80 mg/kg土壤干重。结果表明:(1)香根草可以显著降低土壤中生物有效态Cd和总Cd含量。(2)香根草各部分Cd积累量随处理浓度的增加和处理时间的延长而增加,90 d时80 mg/kg处理组地上部分和根的Cd积累量分别高达180.42 mg/kg和241.54 mg/kg。(3)各浓度Cd处理下,富集系数随着Cd处理浓度的增加而显著降低,随处理时间的延长而升高。(4)香根草地上部分Cd含量小于根部,各处理转移系数均小于1。随着处理时间的延长,中低浓度处理组的转移系数稍有降低,高浓度处理组的转移系数则显著上升。(5)种植香根草使其根际土中残渣态的Cd转化为生物有效态Cd,提高Cd清除效率。研究结果表明,香根草能够有效地吸收土壤中的Cd,降低土壤中总Cd含量,提高土壤安全性,可作为Cd污染地区植物修复的备选物种。     

梯棱羊肚菌Morchella importuna对重金属离子的耐受性研究

以加入6种不同浓度的重金属离子的培养基对梯棱羊肚菌Morchella importuna进行培养的方法,研究其对重金属离子的耐受性。以平板进行培养,测量和计算菌丝平均生长速率和生长促进率,绘制生长曲线获取菌丝生长最佳耐受浓度;采用定性方法对气生菌丝浓密、菌核大小和数量进行描述,获得菌核生成最佳耐受浓度。结果显示:在试验浓度内梯棱羊肚菌对Cr~(6+)、Mn~(2+)、Pb~(2+)、Mo~(6+)、Cu~(2+)具有较强的耐受性,这些重金属离子促进了羊肚菌菌丝生长,而对Cd~(2+)耐受性差,低浓度抑制菌丝生长。促进菌丝生长最适浓度分别为Cr~(6+)100.0mg/L、Mn~(2+)100.0mg/L、Cd~(2+)5.0mg/L、Pb~(2+)50.0mg/L、Mo~(6+)20.0mg/L、Cu~(2+)100.0mg/L,促进菌核生成最适浓度分别为Cr~(6+)50.0mg/L、Mn~(2+)100.0mg/L、Cd~(2+)5.0mg/L、Pb~(2+)20.0mg/L、Mo~(6+)10.0mg/L、Cu~(2+)100.0mg/L。Cd~(2+)抑制菌丝生长临界浓度为介于20.0mg/L与50.0mg/L之间。     

重金属铜、锌、镉复合胁迫对麻疯树幼苗生理生化的影响

该研究以Cu~(2+)、Zn~(2+)、Cd~(2+)单一胁迫为对照,探讨不同浓度的Cu~(2+)、Zn~(2+)、Cd~(2+)复合胁迫对麻疯树幼苗生理生化指标的影响。结果表明:随着Cu~(2+)、Zn~(2+)、Cd~(2+)浓度的增加,麻疯树幼苗叶片中的蛋白质(Pro)、丙二醛(MDA)含量均逐渐增加,其叶片叶绿素含量随着Zn~(2+)胁迫浓度的增加呈现出先降后升的趋势,在中等浓度(100 mg·L-1)的Zn~(2+)胁迫时含量最低、随着Cu~(2+)胁迫浓度的增加叶绿素含量先升高后降低,在Cu~(2+)浓度为200 mg·L-1时含量最高,达到1 200 mg·g-1FW; Cd~(2+)胁迫对叶绿素含量和根系活力无明显影响。根系活力在Zn~(2+)浓度为100 mg·L~(-1)时最强,随着Cu~(2+)浓度的增加而减弱。低浓度的Cu~(2+)、Zn~(2+)、Cd~(2+)对过氧化物酶活性和可溶性糖含量都具有促进作用。Cu~(2+)、Zn~(2+)、Cd~(2+)复合胁迫时对可溶性蛋白、叶绿素和丙二醛含量均无明显影响,随着复合胁迫时浓度的增加,可溶性糖含量和根系活力先增后减。这表明麻疯树对三种重金属的胁迫具有一定的抗性,过高浓度的胁迫会影响麻疯树幼苗生理生化的一些指标,但是麻疯树可以通过自身的防御系统使伤害降到最小。此外,重金属复合胁迫可以在一定程度上减轻单一胁迫对麻疯树幼苗造成的毒害作用。     

镉对超积累和非超积累生态型东南景天内生细菌多样性的影响

重金属胁迫对植物内生细菌群落结构的影响在很大程度上是未知的,目前也很少有研究超积累植物内生细菌的群落结构与多样性对根际土壤中重金属的响应。【目的】探索在不同镉污染水平下,超积累(HE)和非超积累生态型(NHE)东南景天的根系、茎和叶片中内生细菌的群落结构与多样性的变化及其差异性,试图从植物-内生菌之间的相互关系的角度补充解释2种生态型东南景天对有效态镉忍耐和积累能力的差异。【方法】采用Illumina新一代测序方法分析了在不同Cd~(2+)浓度土壤上生长的2种生态型东南景天根、茎和叶中的内生细菌群落结构。【结果】高浓度Cd~(2+)抑制NHE东南景天的生长,内生细菌的丰富度和多样性也降低;然而,高浓度Cd~(2+)促进HE东南景天的生长,茎和根系内生细菌的丰富度增加。在3种土壤上,2种生态型东南景天叶片、茎和根系内生细菌均以变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria)占优势。随着土壤中Cd~(2+)浓度的增加,HE东南景天叶片中Gammaproteobacteria纲、Negativicutes纲和Clostridia纲的相对丰度显著增加,茎中Alphaproteobacteria纲的相对丰度显著增加,Clostridia纲的相对丰度显著减少;NHE东南景天叶片中Alphaproteobacteria纲、Gammaproteobacteria纲和Clostridia纲的相对丰度没有显著变化,茎中Negativicutes纲的相对丰度显著减少,根系中Betaproteobacteria纲和Clostridia纲的相对丰度显著减少,Negativicutes纲却显著增加。在高Cd~(2+)污染土壤(50mg/kg)上,HE东南景天叶片中Sphingomonas属和茎中Veillonella属的相对丰度均大于NHE,且HE东南景天根系内生细菌的第一、第二、第三优势菌Veillonella、Sphingomonas、Prevotella属细菌均没有出现在NHE东南景天根系。【结论】土壤Cd~(2+)污染水平对2种生态型东南景天叶、茎、根中的内生菌群落结构有显著影响。     

重金属镉在番茄及其害虫西花蓟马中的积累与传递

重金属镉(Cd)是农田土壤中的重要污染源,可在植物和植食性昆虫中积累与传递。本文采用水培法,研究了不同浓度的Cd在番茄Solanum lycopersicum不同组织和在其重要害虫西花蓟马Frankliniella occidentalis体内的积累量。结果表明,随着水培营养液中Cd浓度的增加,番茄植株的根、茎和叶中Cd含量呈增长趋势。根中Cd的积累量远高于茎和叶,当水培溶液中Cd含量为20 mg/L时,根、茎和叶中的积累量分别达19 333.67±233.38、122.67±6.84和147.33±2.96 mg/Kg(干重)。随着Cd浓度的增加,番茄根、茎和叶的鲜重和干重均显著下降。西花蓟马取食Cd处理的番茄叶片后,体内Cd显著积累,最高达1.95±0.36 mg/Kg。同时,Cd积累量的提高进一步影响了以番茄叶片为食的西花蓟马的适合度,降低了其存活率。除对照外,番茄茎-叶的转移系数和叶片对Cd的富集系数均大于1,叶片表现出较强的富集能力。而在所有的试验浓度处理中,西花蓟马对Cd的富集系数和转移系数均小于1,表明Cd未在其体内产生生物放大作用。研究结果明确了Cd在番茄各组织及其害虫中的积累和传递水平,为揭示重金属在农业生态系统食物链中的富集效应提供了基础数据。     

Cu2+、Zn2+、Cd2+对黑水虻幼虫生长的影响及在虫体和虫粪的积累

为研究不同金属离子对黑水虻幼虫生长的影响及在虫体和虫粪中的积累分布规律,通过在黑水虻幼虫饲料中加入不同浓度的Cu~(2+)、Zn~(2+)、Cd~(2+),分析观测了幼虫增重、虫体和虫粪中金属含量等情况。结果表明,适量的Cu~(2+)、Zn~(2+)、Cd~(2+)可以促进黑水虻幼虫的生长,Zn~(2+)浓度在400 mg/kg时黑水虻幼虫的体重最高。Cu~(2+)、Zn~(2+)、Cd~(2+)在黑水虻幼虫体内和虫粪中的残留随着饲料中Cu~(2+)、Zn~(2+)、Cd~(2+)浓度的升高而增加。Cu~(2+)、Zn~(2+)在虫体中的残留比例都小于50%,大部分残留在虫粪中,Cd~(2+)在10、20、40 mg/kg处理中虫体的残留比例大于50%,最高达到了91.3%,而在80、160 mg/kg处理中虫体残留量比例小于50%。各重金属在虫粪中的残留主要以残渣态存在,且各形态的含量顺序在高浓度处理中都为残渣态酸溶态水溶态碱溶态。说明饲料中适量金属离子的添加有利于黑水虻幼虫生长,但过量的添加会抑制黑水虻幼虫生长,并造成金属离子的积累。     

丝状真菌生物富集重金属废水的研究进展

重金属废水是对环境污染最严重和对人类危害最大的工业废水之一。丝状真菌生物富集重金属是处理废水的一种重要的方法,近十几年来一直是研究热点。首先介绍了去除废水中重金属的常规方法 :化学沉淀法、离子交换法和吸附法的优缺点。尤其是生物吸附法的独特优点:吸附剂材料廉价,耗费少,吸附重金属离子效率高,适用条件广,生物体吸附剂可重复使用,特别适合于微量重金属废水的处理;其次,介绍了应用到富集重金属的丝状真菌种类,如根霉(Pb~(2+)、Cd~(2+)、Cr5+)、毛霉(Pb~(2+)、Ni~(2+)、Cd~(2+)、Zn~(2+))、曲霉(Pb~(2+))、木霉(Zn~(2+)、Pb~(2+))和担子菌(Cu~(2+)、Pb~(2+)、Cd~(2+))等都在重金属废水中取得较理想的效果;介绍了生物富集重金属的机理,主要是细胞外、细胞表面和细胞内富集重金属离子的机理;最后介绍了影响生物富集重金属效果的几种因素:p H值、重金属离子初始浓度和吸附剂的比例、富集温度、共存离子,展望了丝状真菌富集重金属的研究,旨为推广丝状真菌在富集重金属废水中的应用,并为即将投入新品种的丝状真菌富集重金属的研究奠定基础。     

Genetic and physiological parameters associated with cadmium toxicity in Drosophila melanogaster

Two strains of Drosophila melanogaster represent the extremes in resistance and sensitivity to the lethal effects of CdCl₂. The strain containing the mutations vermilion and brown (v; bw) and the strain Austin had LC₅₀'s of 3.3 and 1.3mm CdCl₂, respectively. The three major chromosomes from these two strains were assorted genetically into the six possible combinations. The measured LC₅₀'s for CdCl₂ for these six genotypes fell into two groups according to the X chromosome; those containing the X chromosome from v; bw had LC₅₀'s 0.5–1.0mm greater than those in which the X chromosome was from Austin. Since the parent strains differed by 2mm, we suggest that the X chromosome is a major, but not the sole, site of genes to produce resistance to CdCl₂. When ¹⁰⁹Cd was in the diet the uptake by v; bw and Austin over 2 days was the same. After 4 days of uptake, the Austin strain excreted the ¹⁰⁹Cd five times faster than v; bw but the six genotypes did not differ appreciably in excretion rate from one another and resembled the sensitive parent Austin more than the resistant one. Thus a second process is indicated that distinguishes resistance to CdCl₂ that apparently is not associated with the X chromosome.This research was sponsored by the Office of Health and Environmental Research, U.S. Department of Energy, under Contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc.     

施氮对镉胁迫下山杨幼苗叶片氮磷钾吸收及镉积累量的影响

为探究山杨在重金属镉胁迫与增施外源氮复合处理条件下的生长及元素积累差异,该研究以山杨幼苗为材料,通过盆栽实验研究在重金属镉(Cd)胁迫下增施外源氮(N)对其形态、叶绿素、淀粉和可溶性糖含量、叶片中全氮(N)、全磷(P)、全钾(K)以及Cd含量的影响。结果表明：(1)单独Cd处理显著抑制山杨幼苗的叶片宽度和茎粗;施加外源N能够缓解Cd胁迫对植株的毒害,其叶长、叶宽和茎粗较单独Cd处理显著增加。(2)单独Cd处理后山杨叶片的叶绿素含量和淀粉含量均比对照显著下降,而其可溶性糖含量显著增加;与单独Cd处理相比,Cd+N复合处理后山杨的叶绿素含量显著增加,淀粉含量却显著下降,而可溶性糖含量略有降低。(3)与对照相比,单独Cd处理后,山杨叶片全N含量显著下降,全P含量显著增加;单独N和Cd+N复合处理后叶片全N含量均显著增加,全P含量均显著下降;全K含量在各处理下均无显著差异。(4)在Cd胁迫下山杨幼苗叶片的Cd含量比对照极显著增加,且Cd+N复合处理后叶片的Cd含量约是单独Cd处理的2倍。研究认为,增施氮素处理可显著提高山杨幼苗对镉胁迫环境的适应能力以及叶片对镉的富集能力。     

外源有机酸对镉胁迫下秋华柳镉积累特征的影响

为探究外源有机酸在加强秋华柳(Salix variegata Franch.)镉积累效率中的应用潜力,采用营养液培养方法,研究了5种100μmol/L外源有机酸(草酸、柠檬酸、酒石酸、苹果酸和琥珀酸)对50μmol/L Cd胁迫下秋华柳生长适应性及Cd积累特征的影响,并通过化学平衡程序VISUAL MINTEQ v3.0计算溶液中不同化学形态Cd(游离态和螯合态Cd)的含量。结果表明:柠檬酸、酒石酸、苹果酸和琥珀酸的添加有效缓解了Cd对秋华柳的毒害,明显促进了秋华柳的生长。除草酸处理组外,其余4个有机酸处理组培养液中游离Cd~(2+)含量均得到较大提升,显著促进了秋华柳对Cd的吸收。柠檬酸、酒石酸、琥珀酸和苹果酸的添加显著提高了秋华柳植株的Cd积累量,分别是未加入有机酸Cd处理组的210%、190%、190%和178%。外源有机酸的施加提高了介质中游离Cd~(2+)的含量,并通过与重金属的络合等作用提升了植株对Cd的吸收和积累能力。但不同有机酸对秋华柳Cd积累特征的影响差异明显,柠檬酸加入后通过提高秋华柳根生物量和根中Cd含量,显著增加了根系Cd积累量;酒石酸、苹果酸和琥珀酸的应用则明显提高了秋华柳地上部分Cd积累量。因此,外源酒石酸、琥珀酸和苹果酸的应用可提高秋华柳地上部分的Cd积累效率,更有利于对Cd污染土壤的修复。     

Estimation of cadmium availability using transformed roots

We have explored cultures of roots transformed by Agrobacterium rhizogenes to test the availability of cadmium in sewage sludges. The toxic effects of Cd and the kinetics of Cd accumulation were examined for three species of transformed roots, grown for 2 weeks in nutrient media, containing Cd as a salt. Roots of sugar beet (Beta vulgaris L.) were highly sensitive, while those of tobacco (Nicotiana tobaccum L.) and morning glory (Calystegia sepium R. Br) were more tolerant. Cd accumulation was higher in sugar beet and morning glory than in tobacco. We developed a non-sterile, 5-day procedure for testing the accumulation (an indication of availability) of Cd from sludge suspensions, using transformed roots of morning glory and tobacco. Cd accumulation varied with plant species and source of sludge. Ranking of Cd availability using this biological assay for Cd accumulation was confirmed by chemical tests with NH₄ acetate and EDTA. Results from transformed roots were also compared with those from normal, excised, tobacco roots and normal and transformed tobacco plantlets. No major alteration in Cd uptake was associated with genetic transformation. We thus demonstrated the feasibility of using transformed roots to estimate the availability of Cd in metal-contaminated materials like sewage sludges.     

Toxicity of inorganic cadmium salts to the microalga Scenedesmus armatus (Chlorophyta) with respect to medium composition, pH and CO2 concentration

Batch cultures of algae grown at low (0.1 %) and elevated (2.0 %) concentrations of CO₂, as well as in original BBM (Bold Basal Medium) and BBM modified with phosphate, EDTA and a combination of both, were exposed to cadmium (Cd(NO₃)₂·4H₂O, 3CdSO₄·8H₂O and CdCl₂·H₂O) for 24 h. Regardless of the salt applied, the concentration-dependent relationships of Cd toxicity were found to be biphasic, suggesting the different affinity of target sites to cadmium. Nominal values of EC₅₀ obtained for algae grown in original BBM and at low CO₂ were 18.0, 16.44 and 15.37 mg·dm⁻³ for cadmium nitrate, sulphate and chloride, respectively. However, it was estimated that 97 % of the free cadmium in the added salts were bound by components of original BBM such as EDTA, phosphates, chloride and sulphate. The effect of Cd-salts at concentrations corresponding to EC₅₀ values on algae were tested in media with 10-fold reduced phosphates (BBM-P), BBM depleted of EDTA (BBM-EDTA) and of both phosphates and EDTA (BBM-P-EDTA). For algae grown at low CO₂ and BBM-P, cadmium was about 25 % less toxic than those applied in original BBM. Cadmium greatly inhibited (about 85 % of the control) the growth of algae cultured in BBM-EDTA; this effect was only slightly dependent on the CO₂ concentration. Deficits of both EDTA and P led to effects similar to those brought about by the absence of EDTA only. The toxicity of cadmium depends on CO₂ concentration only when algae are grown in original BBM. The growth of algae under high CO₂ conditions was reduced considerably less (about 80% of control) compared with low CO₂ concentrations (about 50 % of control). A relationship was found between the toxicity of cadmium salts and final pH values only in variants of low-CO₂ grown algae; with an increase of medium pH the toxicity decreased. The results suggest that both growth conditions and the binding ability of the medium markedly affect the toxicity of cadmium towards microalgae.     

Chromatographic properties of the cadmium induced SOD isoform in Rhizopogon roseolus

Exposure of Rhizopogon roseolus mycelia to 15 mmol·dm⁻³ cadmium for 24 h induces a different pattern of Mn-SOD on polyacrylamide gels, probably being a changed form of an originally existing one. The presence of cadmium affects the chromatographic properties of this enzyme and its mobility through the acrylamide gel. This new isoform was purified using DEAE Trisacryl chromatography. Cadmium induced isoform adsorbed stronger to the ligands and was eluated with a Tris-HCl buffer containing 0.1 mol·dm⁻³ NaCl. SOD from control samples (not treated with cadmium) was eluated with the same buffer without NaCl.     

镉胁迫对姬松茸生长和镉吸收累积的影响

利用外源镉添加的袋栽试验,系统研究了镉对姬松茸J37和J1两菌株农艺性状、子实体产量、氨基酸和镉含量的影响,以求为低富集镉的姬松茸品种选育和安全栽培提供科学依据。结果表明外源镉添加对姬松茸J37和J1品种子实体的农艺性状的影响各异,两菌株单个子实体重量、子实体高度、菌盖直径、菌盖厚度和菌柄直径等均与外源镉浓度具有显著的负相关性,其中子实体重量与外源镉浓度间的相关性最大;15 mg/kg镉水平是两菌株农艺性状发生显著变化的敏感点。不同镉水平下J37菌株单个子实体重量比J1菌株高10.9%—36.6%,表现为较强镉耐受性。姬松茸J37与J1菌株子实体产量、氨基酸和镉含量均随着潮次的增加而降低,子实体产量和氨基酸含量随着外源镉水平增加而降低,而镉含量随外源镉水平增加而增加。与外源镉0mg/kg处理相比,当外源镉水平达15 mg/kg时,J1和J37子实体总产量分别下降23.4%和13.4%以上,J1和J37子实体镉含量分别提高51.5%、13.7%以上,且J1子实体镉含量已达到食品卫生标准的临界值。当外源镉水平达到35 mg/kg时,J1和J37子实体产量分别下降45%、32%以上,J1和J...     

Human glomerular mesangial IP15 cell line as a suitable model for in vitro cadmium cytotoxicity studies

Cadmium represents a major environmental pollutant that may induce severe damage, especially in the kidney where cadmium accumulates. While cadmium is known to severely impair renal tubular functions, glomerular structures are also potential targets. Owing to their contractile properties, glomerular mesangial cells play a major role in the control of glomerular hemodynamics and influence the ultrafiltration coefficient. Cell cultures provide alternative and fruitful models for study of in vitro toxicology. However, the use of primary human mesangial cell cultures is hampered by their limited survival span and their rapid dedifferentiation during passages. This study presents a human stable immortalized mesangial cell line, designated IP15. Cell characteristics were investigated by the detection of known mesangial markers, as well as their ability to contract in response to angiotensin II. IP15 cells were used to investigate cadmium uptake and morphological changes such as cell contraction and cytoskeleton protein expression. The IC₅₀ cytotoxicity index was obtained with 3.55 μmol/L using neutral red assay for 24 h. After cadmium exposure (1 μmol/L, determined as nonlethal concentration), 0.38 μg Cd/mg protein was internalized by the cells as evaluated by inductively coupled plasma optical emission spectrometry (ICP/OES). Cadmium induced a significant cell surface reduction that correlated with smooth-muscle α-actin disorganization. Thus, the IP15 cell line is a suitable model for study of in vitro cadmium cytotoxicity in mesangial cells and allows sufficient material to be obtained for future studies of the intracellular effects of cadmium exposure.     

Energetic basis of cadmium toxicity in Staphylococcus aureus

In washed cells of cadmium-sensitive Staphylococcus aureus 17810S oxidizing glutamate, initial Cd²⁺⁺⁺ influx via the Mn²⁺ porter down membrane potential () was fast due to involvement of energy generated by two proton pumps—the respiratory chain and the ATP synthetase complex working in the hydrolytic direction. Such an unusual energy drain for rapid initial Cd²⁺ influx is suggested to be due to a series of toxic events elicited by Cd²⁺ accumulation down generated via the redox proton pump: (i) strong inhibition of glutamate oxidation accompanied by a decrease of electrochemical proton gradient ( _H ⁺) formation via the respiratory chain, (ii) automatic reversal of ATP synthetase from biosynthetic to hydrolytic mode, which was monitored by a decrease of _H ⁺-dependent ATP synthesis, (iii) acceleration of the initial Cd²⁺ influx down generated the reversed ATP synthetase, the alternative proton pump hydrolyzing endogenous ATP. The primary, cadmium-sensitive targets in strain 17810S seem to be dithiols located in the cytoplasmic glutamate oxidizing system, prior to the membrane-embedded NADH oxidation system. Inhibition by Cd²⁺ of _H ⁺-dependent ATP synthesis and of pH gradient (pH)-linked [¹⁴C]glutamate transport is a secondary effect due to cadmium-mediated inhibition of _H ⁺ generation at the cytoplasmic level. In washed cells of cadmium-resistant S. aureus 17810R oxidizing glutamate, Cd²⁺ accumulation was prevented due to activity of the plasmid-coded Cd²⁺ efflux system. Consequently, _H ⁺-producing and -requiring processes were not affected by Cd²⁺.