入侵植物假苍耳对土壤中铜、铅重金属污染的富集特征

通过室内盆栽试验研究入侵植物假苍耳(Iva xanthifolia)在营养生长阶段对铜、铅的耐性及富集特征。实验结果表明,在1~16 mg·L^-1的添加铜处理及0.5~14 mg·L^-1的添加铅处理条件下,假苍耳对铜、铅两种单一金属均有很强的耐性及富集作用,重金属在植物体地上部和地下部的富集量分别为607.59、137.20,404.38、34.53 mg·kg^-1,对应的富集系数为11.39、4.18,转运系数4.43、11.71,且重金属在植物体内的分布规律均表现为：茎部＞叶片＞根部,地上部分的积累量远大于地下部分。对叶色、株高及生物量等特征的观察表明假苍耳的生长未受到抑制,符合超富集植物的基本特征。与一般超富集植物相比,假苍耳作为一种外来入侵植物,具有生长迅速、植物材料易得,生物量大且分布范围广的优点。     

铜胁迫对水花生生长及活性氧代谢的影响

采用水培实验,研究了不同浓度铜胁迫下水花生(Alternanthera philoxeroides)生长特性和体内生理特性的变化规律。结果表明：铜胁迫抑制植株正常生长;当铜浓度＜5mg·L^-1时,植物细胞内的SOD、POD和CAT酶活性均有所升高;当铜浓度＞5 mg·L^-1时,随着铜浓度增加,植株生长缓慢,生物量下降,叶片叶绿素含量下降,植物体内活性氧清除系统中的SOD、POD和CAT 3种酶的活性又逐渐下降,细胞膜透性增大和MDA含量高度积累,影响植物的正常生长代谢,且铜浓度为10 mg·L^-1时植株外观表现重度伤害。     

重金属Pb(Ⅱ)对3种藜科植物种子萌发的影响

以珍珠猪毛菜（Salsola passerina Bunge）、地肤（Kochia scoparia(L.)Schrad.）和白藜（Chenopodium album L.）3种藜科植物为研究对象,研究不同浓度（0、50、150、300、600、800、1 000 mg·L^-1）的Pb(Ⅱ)处理对植物种子萌发和幼苗生长的影响。结果表明：当Pb(Ⅱ)浓度为50和150 mg·L^-1时,珍珠猪毛菜和地肤种子的发芽率、发芽势和发芽指数与对照相比差异不显著,Pb(Ⅱ)浓度为150 mg·L^-1时,对白藜种子发芽率、发芽势和发芽指数有明显影响,Pb(Ⅱ)浓度大于300 mg·L^-1对3种植物种子萌发均有抑制作用,对白藜和地肤的抑制大于珍珠猪毛菜。3种植物的种子活力指数除珍珠猪毛菜在50 mg·L^-1时与对照无显著差异,其余各处理均与对照有极显著差异。Pb(Ⅱ)浓度为50 mg·L^-1时,对3种植物的胚根长和胚芽长都影响不大,随着Pb(Ⅱ)浓度的升高,对3种植物的胚根长和胚芽长都有明显的抑制作用,对地肤和白藜的抑制强度更大。地肤和白藜幼苗分别在Pb(Ⅱ)浓度为300和600 mg·L^-1时死亡,当Pb(Ⅱ)浓度达到1 000 mg·L^-1时,珍珠猪毛菜仍可生长,但生长比较缓慢。3种植物幼苗对Pb(Ⅱ)的耐受性为：珍珠猪毛菜＞白藜＞地肤。     

杜仲叶片愈伤组织诱导的激素优化研究

以杜仲优树L33的幼叶为材料,在B5培养基上添加不同浓度的生长素与细胞分裂素进行愈伤组织诱导研究,结果表明：无激素的培养基上不能诱导出愈伤组织,单独加入2,4-D、NAA和IBA均可诱导出愈伤组织,以0.5 mg·L^-1 2,4-D、0.5～1.0 mg·L^-1 NAA、1.0 mg·L^-1 IBA出愈率最高,达100%,且愈伤组织生长较好;在适宜浓度的生长素的培养基上加入细胞分裂素时,KT的加入对愈伤组织的诱导及生长起抑制作用;1.0 mg·L^-1 NAA+0.3～0.5 mg·L^-1 BA与1.0 mg·L^-1 IBA+0.3～0.5 mg·L^-1 BA 的组合可明显促进愈伤组织的诱导和生长,适合进一步继代培养。     

马蔺组织培养快繁技术体系研究

以成熟且具活力的马蔺种子为外植体,以MS为基本培养基,与不同浓度比例的2,4-D、BA、NAA、KT等植物生长调节剂构成愈伤组织诱导、分化、生根等培养基的组合方案,对马蔺组织培养快繁技术开展系统研究。结果表明,不同植物生长调节剂组合的培养基对愈伤组织的诱导率有显著影响,MS+2,4-D 4 mg·L^-1+BA2 mg·L^-1、MS+2,4-D 4 mg·L^-1+BA5 mg·L^-1和MS+2,4-D 2 mg·L^-1+KT1.5 mg·L^-1为最佳诱导培养基,诱导出愈率均在58%以上,显著高于其它培养基组合方案（p<0.05）;最佳分化培养基为MS+BA4 mg·L^-1和MS+BA1 mg·L^-1+NAA0.15 mg·L^-1,绿苗分化率高达100%,生长势好,状态叶和分化芽丛质量好;适宜继代增殖培养基为MS+BA2 mg·L^-1+NAA0.1 mg·L^-1、MS+BA1 mg·L^-1+NAA0.2 mg·L^-1;1/2MS为最适宜的生根培养基,1/2MS+IBA0.5 mg·L^-1、1/2MS+IBA0.5 mg·L^-1+NAA0.5 mg·L^-1两种组合也相对较好;试管苗不需炼苗可直接出瓶移栽于V_田土∶V_河沙=2∶1的土壤基质,成活率在95%以上。从而为马蔺提供了一套从“成熟种胚—诱导愈伤组织—绿苗分化—继代增殖—生根—试管苗移栽”等整个过程中各环节的最佳培养基和操作规程的组培快繁体系。     

镉胁迫对矮牵牛种子萌发、幼苗生长及抗氧化酶活性的影响

采用营养液培养的方法研究了不同浓度镉Cd（0、1、2和4 mmol·L^-1）处理对矮牵牛（Petunia hybrida）种子萌发、幼苗生长及生理特性的影响。结果发现：与对照相比,较低浓度（1 mmol·L^-1）Cd处理下矮牵牛种子萌发和幼苗生长均显著被抑制,当Cd浓度增至4 mmol·L^-1时完全抑制了矮牵牛种子的萌发。Cd胁迫在低浓度时激活矮牵牛幼苗叶片过氧化物酶（POD）、过氧化氢酶（CAT）活性,而高浓度产生抑制效应;抗坏血酸过氧化物酶（APX）和超氧化物歧化酶（SOD）活性与对照相比均显著升高,丙二醛（MDA）含量无显著变化。不同浓度的乙二胺四乙酸(EDTA)的加入使4 mmol·L^-1 Cd胁迫下矮牵牛幼苗叶片POD和APX活性增加,但不影响SOD和CAT活性;此外,6 mmol·L^-1 EDTA使Cd胁迫下矮牵牛幼苗叶片中MDA含量增加。结果表明,Cd胁迫抑制矮牵牛种子萌发和幼苗生长,却使幼苗叶片POD、CAT和APX活性增加,EDTA的加入能够进一步提高Cd胁迫幼苗POD和APX活性。因此,矮牵牛幼苗在Cd胁迫下具有较强的抗氧化损伤的能力。     

镧对镉胁迫下大蒜幼苗生长及镉积累的影响

采用土培实验研究了镧(La²⁺)对镉(Cd)胁迫下大蒜幼苗生长及Cd积累的影响。结果表明：低浓度Cd（＜5 mg·kg^-1）对大蒜生长有微弱的促进作用而高浓度Cd对其有明显抑制作用。外施系列浓度La²⁺对高浓度Cd胁迫下大蒜幼苗生长具有明显的缓解效应,单株鲜重、干重、根长及地上部分高度均具有明显或不同程度的增加。测定结果表明,Cd主要积累在大蒜根部而向地上部分转运的较少,外施系列浓度La²⁺对高浓度Cd胁迫下大蒜幼苗根系对Cd积累具有显著的抑制效应,同时也抑制Cd向地上部分转运。从外施La²⁺对高浓度Cd胁迫下大蒜幼苗生长及大蒜对Cd积累情况来看,La²⁺的适宜缓解效应浓度是在Cd浓度为20 mg·kg^-1时,La²⁺浓度为10～15 mg·kg^-1;在Cd浓度为40 mg·kg^-1,La²⁺浓度为5 mg·kg^-1。     

野葛叶片和茎段高频再生体系的建立

探讨几种因子对野葛叶片和茎段高频再生体系建立的影响。采用植物组织培养、正交实验和单因子实验的方法。野葛叶片和茎段的最佳消毒方式为70%酒精处理30 s后再用0.1%HgCl₂处理15 min;野葛叶片愈伤组织诱导的最佳培养基为MS+NAA 1.0 mg·L^-1+2,4-D 2 mg·L^-1,野葛茎段愈伤组织诱导的最佳培养基为MS+NAA 0.5 mg·L^-1+6-BA 1.0 mg·L^-1+2,4-D 2 mg·L^-1;暗培养更有利于野葛愈伤组织的诱导;野葛叶片和茎段愈伤组织诱导的最佳蔗糖浓度均为30 g·L^-1;野葛叶片愈伤组织的最佳出芽培养基为MS+NAA 1.0 mg·L^-1+6-BA 3.0 mg·L^-1,而野葛茎段愈伤组织的最佳出芽培养基为MS+ NAA 0.5 mg·L^-1+KT 2 mg·L^-1;光照培养更有利于野葛叶片和茎段愈伤组织芽的再分化;野葛叶片愈伤组织再生芽生根的最佳培养基为MS+NAA 0.5 mg·L^-1+PP₃₃₃ 0.5 mg·L^-1,而野葛茎段愈伤组织再生芽生根的最佳培养基为MS+NAA 0.5 mg·L^-1+PP₃₃₃ 3.0 mg·L^-1;野葛叶片和茎段愈伤组织再生芽生根的最佳蔗糖浓度均为30 g·L^-1;叶片再生苗移栽的最佳PP₃₃₃浓度为1.0 mg·L^-1,茎段再生苗移栽的最佳PP₃₃₃浓度为3.0 mg·L^-1;叶片和茎段再生苗的最佳移栽基质均为蛭石:珍珠岩（2:1）。     

一种新发现的铜积累植物——密毛蕨

对铜尾矿上生长的密毛蕨(Petridium revolutum)进行了野外调查分析和温室营养液砂培实验.结果表明,密毛蕨所生长的废铜矿土壤中Cu含量平均为2 432 mg·kg^-1 DW,最高达7 554 mg·kg^-1 DW;地上部生物量平均为18.33 g·plant^-1 DW,最高达40.05 g·plant^-1 DW;地上部Cu含量平均为201 mg·kg^-1 DW,最高达567 mg·kg^-1 DW;地下部Cu含量平均为346 mg·kg^-1 DW,最高达1 723 mg kg^-1 DW;密毛蕨对Cu的转移系数平均为0.81,最高达3.88.在营养液砂培的条件下,Cu 7 mg·L^-1处理没有抑制密毛蕨地上部的生长;密毛蕨体内的Cu含量随着介质中Cu浓度的增加而显著增加,但是大部分的Cu积累在地下部.密毛蕨对Cu具有较强的忍耐和较高的积累能力,可作为修复Cu污染土壤的新材料.     

镉对灵芝菌丝抗氧化系统的影响

研究了不同浓度镉(Cd) (0、10、50、100、200和400 μmol·L^-1)对灵芝菌丝抗氧化系统的影响.结果表明,随着Cd浓度增加,菌丝鲜质量、脯氨酸、总糖和还原糖含量逐渐下降,非蛋白巯基化合物（NPT）水平逐渐上升,当Cd浓度达到400 μmol·L^-1时,NPT含量急剧上升至对照组的6.7倍.在试验浓度范围内,灵芝菌丝体过氧化物酶（POD）、谷胱甘肽还原酶（GR）和过氧化氢酶（CAT）活性呈显先上升后下降的变化趋势,并均在Cd浓度为100 μmol·L^-1时达峰值;超氧化物歧化酶（SOD）和脂氧合酶（LOX）活性则随着Cd浓度的增加而逐渐上升,在Cd浓度为400 μmol·L^-1时达峰值.采用聚丙烯酰胺凝胶电泳分析Cd胁迫下灵芝菌丝抗氧化酶的同工酶谱发现,100～400 μmol·L^-1 Cd处理诱导出2条Mn-SOD型同工酶带;10～200 μmol·L^-1 浓度Cd上调组成型CAT、SOD、POD和LOX同工酶的表达强度;而400 μmol·L^-1 Cd的则显著抑制了POD同工酶的表达.     

Accumulation of cadmium in rat liver cadmium binding protein following single and repeated cadmium administration.

The accumulation of cadmium in rat liver cadmium binding protein induced by single and repeated intraperitoneal injections of CdCl2 and the de novo biosynthesis of CdBP were studied by using 109Cd to measure cadmium binding in the CdBP and 35S incorporation as indicator of protein synthesis. The biosynthesis of CdBP is controlled by the cadmium concentrations. For single doses up to 1 mg Cd2+/Kg b.w. about 50% of the cadmium is present in the soluble fraction of liver bound to CdBP and the incorporation of 35S-cysteine is linear with the cadmium concentration. When single doses ranging from 1 to 3 mg Cd2+/Kg b.w. are administered the fractions of both 35S-cysteine and cadmium incorporated into de novo synthesized CdBP gradually decrease. For single doses higher than 3 mg Cd2+/Kg b.w. the biosynthesis capability is maximum and 20 mug Cd/g liver can be incorporated into the de novo biosynthesized CdBP. When rats are treated every day with amounts of cadmium of about 0.8 mg Cd2+/Kg b.w. for up to 8 days a dose-proportional increase in both Cd incorporation and CdBP biosynthesis are observed. This shows a cumulative incorporation of cadmium in the de novo biosynthesized CdBP. Experiments carried out by injecting 65ZnCl2 and 203HgCl2 every day showed that they are not accumulated like cadmium and do not induce the biosynthesis of rat liver CdBP after repeated administration over 7 days.     

Incorporation of cadmium into proteins in a cadmium tolerant fungi

Aspergillus carbonarius and a strain of Penicillium, a cadmium tolerant fungi, are able to metabolize cadmium chloride up to 2% (w/v). Their amino acids analysis on cadmium free and cadmium chloride containing media indicated certain disorders in their metabolic activities. Cystathionine was only detected in both fungi in the presence of cadmium chloride. However, cadmium was incorporated into several types of low and high molecular weight proteins. The amino acids hydrolyzates of a cadmium containing protein are characterized by the presence of high levels of sulfur amino acids; cysteine and methionine. Ethylasparagine was detected in the hydrolyzate of that cadmium containing protein as well.     

水稻镉安全材料的镉吸收动力学特征

采用水培试验,以前期筛选出的水稻Cd安全材料D62B为试验材料,普通材料泸恢17为对照材料,在不同Cd浓度和时间处理下,研究水稻Cd安全材料的Cd吸收动力学特性.结果表明: 在不同Cd处理时间下,D62B根系对Cd的吸收总量均低于泸恢17,且随吸收时间的延长,差异逐渐增大.当吸收时间达到72 h,泸恢17体内积累的Cd总量为D62B的1.3倍.两种水稻材料Cd吸收动力学符合米氏方程,米氏方程常数(K_m)值差异不大,但泸恢17的最大吸收速率(V_max)是D62B的2倍.当Cd处理时间大于48 h,D62B根系对Cd的转移系数低于泸恢17,且其根部Cd分配比例明显大于泸恢17,即D62B根系对Cd的固持能力大于泸恢17.D62B的Cd吸收能力较弱,且其向地上部转移Cd的能力显著低于泸恢17.     

Biochemical response to cadmium

The effect of daily oral administration of ethanol (2.5, 5, or 10% in drinking water for 8 wk), lead (10 mg/kg, po, once daily for 8 wk), or their combination on tissue trace-metal concentration and hematopoietic and hepatic biochemical indices was investigated in male rats. Ethanol (10%) ingestion enhanced the hepatic lipid peroxidation and decreased the calcium and magnesium content of blood and liver. Coexposure to lead and ethanol (5 and 10%) produced a more pronounced elevation of blood zinc protoporphyrin (ZPP) and hepatic lipid peroxidation. Combined lead-ethanol exposure also lowered the concentration of blood and hepatic magnesium and calcium and increased the amount of lead in the blood, liver, and brain compared to a group treated with lead alone. The results suggest that chronic alcohol ingestion results in calcium and magnesium loss. However, coexposure to lead and ethanol could result in more serious depletion of calcium and magnesium, and this could be the cause of suspected synergism between alcohol consumption and lead poisoning.     

Variation in cadmium accumulation potential and tissue distribution of cadmium in tobacco

Variation in Cd accumulation between Nicotiana species but not varieties has been observed in seedlings grown in solution culture with moderate-to-low levels of Cd. Nicotiana tabacum has been characterized as a leaf and root accumulator while Nicotiana rustica is shown to be primarily a root accumulator, having about half the leaf Cd per gram dry weight of N. tabacum. This phenotype is retained in the mature N. rustica plant. To characterize these two species which differ in their modes of Cd accumulation, tissue Cd distribution, partitioning of metal in soluble and insoluble fractions and the contribution of soluble Cd-binding proteins (peptides) to total plant Cd was assessed using mature solution cultured plants. Metal accumulation was highest in the most mature leaves and in young roots. The preponderance of young roots in N. rustica may, in part, account for low leaf/high root Cd accumulation in this species. While Cd-binding peptides appear to be a principal form of Cd in leaves and roots of seedlings and these also occur in mature leaves, Cd is equally distributed between soluble (about 80% as Cd-binding peptide) and uncharacterized insoluble forms in mature plant roots.     

Stimulation of cadmium uptake in relation to the cadmium content of plants

The time course of cadmium uptake by the roots of intact tomato plants (Lycopersicon esculentum Mill.) was measured in a nutrient solution with a micromolar cadmium concentration until all cadmium in the medium was exhausted. Exhaustion taking a few hours, cadmium was repeatedly added to the nutrient solution. The initial rate of cadmium uptake was computed for each cadmium addition. This rate sharply increased and ultimately leveled off, the maximum value being about three times higher than the value measured after the first cadmium addition. The stimulating effect of cadmium was associated with an inhibitory effect at higher levels of cadmium concentrations. An increase in the net cadmium influx with time could not be explained by the binding of heavy metal to a fixed number of organic compounds. Conceivably, the production of binding sites could be increased and cadmium might play a part in controlling the rate of sites production.     

Antioxidant capacity and cadmium accumulation in parsley seedlings exposed to cadmium stress

Parsley (Petroselinum hortense L.) plants cultivated under controlled conditions were exposed to different doses of cadmium to investigate the antioxidant capacity and cadmium accumulation in the samples. Two-months-old parsley seedlings were treated with four different concentrations of CdCl₂ (0, 75, 150, and 300 μM) for fifteen days. Cadmium level in leaves increased significantly by increasing the Cd contamination in the soil. Total chlorophyll and carotenoid content declined considerably with Cd concentration. Cd treatment caused a significant increase lipid peroxidation in tissue of leaf. Superoxide dismutase activity (SOD, EC 1.15.1.1) increased partially at 75 and 150 μM CdCl₂ concentrations whereas the activity decreased at 300 μM CdCl₂. Catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) activities were reduced by Cd application. Total phenolic compound amount increased significantly with increasing Cd concentration, as ferric reduction power, superoxide anion radical, and DPPH˙ free radical scavenging activities elevated slightly by the concentration. These results suggest that antioxidant enzymes activities were repressed depending on accumulation of cadmium in leaves of parsley while the non-enzymatic antioxidant activities slightly increased.     

Absorption of cadmium after a long-term oral administration of cadmium to dogs

A long-term experiment using beagle dogs to investigate the absorption of cadmium was conducted. The dogs in the experimental groups were given a commercial diet and pelleted food containing 1, 3, 10, 50, and 100 mg of cadmium per day. The cadmium concentration in the blood increased continuously, gradually reaching a steady state following the administration of cadmium. The cadmium excreted daily in urine increased continuously. The cumulative excreted amount of cadmium in urine was calculated by using the trapezoidal rule based on the data of excretion of cadmium in urine. Then the absorbed fraction of administered cadmium was estimated on the basis of the relationship between the cumulative excreted amount of cadmium in urine and the cumulative administered dose of cadmium after the cadmium concentration in blood reached a steady state. The absorbed fraction of cadmium decreased with an increase in the administered dose of cadmium. A dose-dependent increase between the absorbed amount and the administered dose was observed.