单一与复合砷锑处理对波士顿蕨富集与转化砷和锑的作用

通过水培试验,研究了单一和复合砷锑处理对波士顿蕨(Nephrolepis exaltata L.)植株各部位及其亚细胞砷锑富集和形态转化的影响,以期查明植物体内砷与锑之间可能的相互作用。结果表明,与对照组相比,单一和复合处理条件下,波士顿蕨各部位砷锑含量均有显著的增加,砷含量表现为根叶柄羽叶,锑含量表现为根羽叶叶柄。与20 mg·L-1单一Sb(III)处理相比,复合处理条件下,随着砷的同时加入(10 mg·L-1As)植株各部位锑含量出现下降,同时根部细胞器中的锑出现向细胞壁与胞液转移、而羽叶与叶柄出现由细胞壁向其他两个亚细胞组分转化的现象;与10 mg·L-1单一As(III)处理相比,复合处理条件下,锑的加入(20 mg·L-1Sb)显著降低了波士顿蕨各部位砷的含量,同时促进了根部细胞壁中的砷向胞液与细胞器转移,以及羽叶与叶柄胞液处砷向细胞壁与细胞器的转移。因此,波士顿蕨体内,砷锑之间具有拮抗作用。单一As(III)处理下,波士顿蕨根部以As(V)为主、羽叶主要以DMA为主,而Sb(III)的同时加入则能够促进As(III)更多地向As(V)和DMA转化;单一Sb(III)处理下,波士顿蕨体内以Sb(III)为主导形态,随着As(III)的同时加入,在波士顿蕨根与叶柄处,As(III)强烈地抑制Sb(III)向Sb(V)转化,相反在羽叶处却会促进Sb(III)向Sb(V)转化。     

贵州独山锑矿区土壤-头花蓼系统中重金属的分布特征

通过野外调查采样,分析贵州独山锑矿区土壤6种重金属(Sb、As、Cd、Zn、Pb、Mn)含量及其在头花蓼不同部位的分布特征。结果表明:矿区土壤Sb、As、Cd、Zn、Pb和Mn的平均含量分别为1566.55、23.98、1.21、117.81、34.27和460.98 mg·kg-1,Sb、As、Cd、Zn含量分别为贵州省土壤背景值的699.35、1.20、4.88和1.18倍,且土壤中Sb与As呈显著正相关性(P0.05),具有同源性。内梅罗综合污染指数法评价表明,矿区土壤重金属污染指数为112.75~1295.22(平均500.37),为重度污染水平。头花蓼在锑矿区污染土壤中具有较强的耐受性,且Sb、Mn在头花蓼各部位的含量分布分别为根叶茎花、叶花根茎,As、Cd、Zn、Pb无明显规律。矿区头花蓼各部位的As、Cd、Pb含量均未超过《中医药-中草药重金属限量》国际标准值,但该矿区头花蓼中的Sb对人体的健康存在一定健康风险。     

某关闭汞矿区附近农田蔬菜中的汞污染评价

研究了某汞矿区附近蔬菜地的汞污染现状及其对周围居民的健康风险。通过汞矿区附近连片菜地所采集的15种蔬菜中总汞含量的分析发现,不同蔬菜的汞含量水平依次为叶菜类茄果类块茎类,其中叶菜类生菜的汞含量最高(57 mg·kg-1),块茎类白萝卜的汞含量最低(1.67 mg·kg-1)。对叶菜类和块茎类蔬菜不同部位的汞含量分析发现,同种蔬菜的不同部位对汞的富集能力不同。无论叶菜类还是块茎类,地上部分的汞含量均高于地下部分。其中,叶菜类蔬菜地上部分的外叶、内叶和混合叶的汞含量水平为外叶混合叶内叶。红萝卜和白萝卜各部位对汞的富集能力相似,即叶片萝卜表皮萝卜根。同时,对研究区中13个点位大气和土壤总汞含量分析表明,大气中总汞的含量在128~1109ng·m-3,土壤中总汞的含量水平为3.88~91.62 mg·kg-1,均严重超标。通过对汞矿区居民摄入蔬菜的汞暴露评估与健康风险评价可知,单独蔬菜摄入不会危及附近居民健康,但若综合其他暴露途径,潜在健康风险较高。     

外源铁对铅污染土壤中宽叶香蒲铅积累的影响

采用温室盆栽方法,研究添加外源铁对不同铅浓度(0、100、500和1000 mg·kg-1)污染土壤中宽叶香蒲铅积累的影响.结果表明:各铅浓度条件下,与添加100 mg Fe·kg-1相比,添加500 mg Fe·kg-1处理的宽叶香蒲地上部和根的铅含量均增高.土壤铅浓度为1000mg·kg-1时,添加500 mg Fe·kg-1处理根的铅含量比100 mg Fe·kg-1处理增加33.7％,地上部铅含量增加50.5％.添加500 mg Fe·kg-1处理的根际土壤中可交换态铅比100mg Fe·kg-1处理增加77.0％～114.6％.除500 mg·kg-1铅浓度外,各铅浓度条件下添加500mg Fe·kg-1处理根干质量均显著低于100 mg Fe·kg-1处理.在铅污染的湿地环境中添加适量铁可以提高铅的有效性,促进铅积累.     

硒镉处理对萝卜硒镉吸收的影响及其交互作用

采用盆栽试验的方法,研究不同含量的硒、镉单一和复合作用对萝卜生长及其对硒、镉吸收的影响。结果表明:适量的硒(2.5~5.0 mg·kg-1)可以促进萝卜的生长,表现为萝卜发芽率提高43%、叶片SPAD值提高22%、生物量增加50%;镉单一污染时,镉显著抑制萝卜的生长(P0.05);土壤中硒的浓度低于1.5 mg·kg-1时对镉含量5.0 mg·kg-1具有拮抗作用,同时可以促进萝卜的生长;萝卜中硒的浓度随着土壤中硒的添加量的增加而增加,对硒的富集效果明显,且地下部分对硒的吸收能力大于地上部分;土壤中硒浓度5.0 mg·kg-1时,5.0 mg·kg-1镉的存在不影响萝卜对硒的吸收;当土壤中硒的浓度为5.0~10.0 mg·kg-1时,镉的存在虽然影响萝卜对硒的吸收,但萝卜中硒的含量仍处于稳定积累状态;而当土壤中硒浓度≥10.0 mg·kg-1时,镉的存在会抑制萝卜对硒的吸收,且这种作用表现为地上部分强于地下部分;硒能显著降低萝卜对镉的吸收,且这种作用表现为地下部分强于地上部分。因此,在轻度镉污染的土壤中种植富硒萝卜,既能生产营养安全的富硒食品,又可实现污染农田的再利用。     

石门雄黄矿周边地区土壤砷分布及农产品健康风险评估

对石门雄黄矿区周边土壤和作物进行了系统研究.结果表明:矿区表层(0～20cm)土壤砷含量平均为99.51mg·kg-1,比湖南省土壤砷含量背景值高出5.34倍,为当地普通农田土壤的9.70倍;矿区水田和旱地表层土壤砷含量分别为43.51和115.1mg·kg-1,分别超出国家土壤环境质量II级标准0.45和1.87倍,相应的表层土壤样本超标率分别为62.5%和50.0%;矿区粮食作物、蔬菜和水果可食部位砷含量分别为0.16、0.06、0.01mg·kg-1,作物样本超标比例由高至低的顺序为粮食作物蔬菜水果,其中以稻米、红薯中砷含量超标较严重,稻米砷含量最高达0.84mg·kg-1,超过国家食品质量标准4.6倍,样本超标率达62.5%.土壤砷含量与作物砷含量呈极显著正相关(P0.01),当地居民通过食用矿区农产品进入人体的平均日摄取砷量为6.416μg·kg-1·d-1,远高于WHO的推荐标准,相应人群健康风险指数为21.39,是对照区的15.39倍.     

超积累生态型东南景天吸收锌的特性

采用水培和盆栽方法研究超积累生态型东南景天吸收锌的特征。在水培条件下,1μmol·L-1Zn处理,根系Zn含量随着处理时间的增加而缓慢增加,叶片和茎Zn含量在处理2d后达到最大值,随着培养时间的延长,其含量略有下降。500μmol·L-1Zn处理水平下,叶片和茎Zn含量随着处理时间的增加而增加,处理16d后基本上达到稳定,根系Zn含量在0～16d增加缓慢,但处理16d后急剧上升。当溶液Zn浓度为1～500μmol·L-1,叶片和茎Zn含量随营养液中Zn浓度的增加而增加,而根系Zn含量增加缓慢;当溶液Zn≥1000μmol·L-1时,叶片和茎Zn含量急剧下降,而根系Zn含量迅速增加。盆栽条件下,当土壤Zn含量较低时时,土壤Zn促进东南景天的生长。5月13日和7月21日收获的植株地上部的干物质量分别在400mg·kg-1(0.71g盆-1)和800mg·kg-1(1.45g盆-1)处理达到最大值。但当土壤Zn添加量≥1600mg·kg-1时,植物的生长受到抑制。随着土壤中Zn添加量的增加,东南景天地上部Zn浓度变化趋势基本上与其生物量的变化一致。5月13日收获时,当土壤Zn添加量≤1600mg·kg-1,地上部Zn含量随着土壤Zn浓度的增加而增加,在1600mg·kg-1处理达到最大值,约为17000mg·kg-1(DW)。7月21日收获的结果显示,当土壤Zn添加量≤800mg·kg-1,地上部Zn含量随着土壤Zn浓度的增加而增加,最大值为29000mg·kg-1(DW);但当土壤Zn添加量≥1200mg·kg-1时,地上部Zn含量反而随着土壤Zn含量的增加而显著降低。     

东北山地灌木沼泽植物铜、锌分布特征及季节动态

研究了东北山地灌木沼泽主要植物--细叶沼柳、五蕊柳、丛苔草和修氏苔草中Cu、Zn分布、积累及其季节动态.结果表明:Cu含量变动范围为6～12 mg·kg-1,细叶沼柳和五蕊柳各器官Cu含量为根》枝》叶;丛苔草和修氏苔草为茎》叶》根,Cu主要积累在灌木的根系和苔草的茎叶中,灌木和苔草中Cu含量相差较小.Zn含量变动在30～250 mg·kg-1之间,细叶沼柳和五蕊柳各器官Zn含量为叶》枝》根,尤其是叶和枝中都在150 mg·kg-1以上;丛苔草和修氏苔草各器官Zn含量为根》茎》叶.Zn多积累在灌木的叶和苔草的根中,且灌木各器官Zn含量明显高于苔草.细叶沼柳和五蕊柳各器官对Zn的富集系数均大于1.45,显示出较强的Zn富集能力.4种供试植物在生长初期地上部分Cu、Zn含量较高,且随着季节变化呈波动式降低趋势,而根中则表现出生长初期和末期Cu、Zn含量较高的特点.     

镉在不同类型蕹菜(Ipomoea aquatica Forsk.)中的积累及其化学形态和分子分布

采用水培幼苗试验研究不同蕹菜品种("台湾308"和"强坤青骨")Cd的积累及其化学形态和分子分布。结果表明,1.0 mg·L-1Cd浓度处理下,"台湾308"和"强坤青骨"叶、茎、根Cd含量分别为3.17、3.55、39.1和2.06、2.35、33.5 mg·kg-1;5.0 mg·L-1Cd浓度处理下,"台湾308"和"强坤青骨"叶、茎、根Cd含量分别为3.75、4.15、55.8和2.68、3.43、83.7 mg·kg-1。2个蕹菜品种Cd化学结合形态研究表明,叶中以乙醇提取态为主,茎、根中以乙醇和氯化钠提取态为主。"台湾308"叶、茎、根中活性较强的水提取态Cd所占比例均明显高于"强坤青骨",而醋酸和盐酸提取态Cd所占比例均明显低于"强坤青骨"。Cd处理水平和蕹菜品种类型对体内Cd化学结合形态均有一定影响,在根中表现尤为明显。分子分布结果表明,蕹菜叶片可溶部分中的Cd大部分与高分子量化合物和小分子量物质相配合,而根中可溶部分的Cd主要与植物螯合肽(PCs)和分子量为10~20 kDa的蛋白质结合。"强坤青骨"根系中Cd与PCs配合的组分(Cd-PCs)含量小于"台湾308",降低了Cd向地上部转运的可能性,进而成为其地上部分Cd含量较低的原因之一。     

微生物氧化As(Ⅲ)和Sb(Ⅲ)的研究进展

砷(Arsenic,As)和锑(Antimony,Sb)属于同族元素,具有相似的化学性质,是公认的有毒类金属(Metalloid),广泛存在于自然界中。随着人类的发展,环境中砷和锑的污染日益严重,类金属污染环境的修复已经刻不容缓。现已表明,自然界中的微生物在砷和锑的生物地球化学循环中发挥着重要的作用,尤其是微生物的氧化作用,可以将毒性较强的亚砷酸盐[Arsenite,As(Ⅲ)]和亚锑酸盐[Antimonite,Sb(Ⅲ)]氧化为毒性较低的砷酸盐[Arsenate,As(V)]和锑酸盐[Antimonate,Sb(V)],被认为是一种潜在的类金属污染环境修复方法。本文就国内外对As(Ⅲ)氧化菌和Sb(Ⅲ)氧化菌的多样性、As(Ⅲ)和Sb(Ⅲ)微生物氧化调控机制和应用的研究进展进行总结,旨在为深入了解和探索微生物介导的砷和锑生物地球化学循环及污染环境的微生物修复提供参考。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.