甘蓝型油菜种质萌发期耐砷性综合评价与筛选

为了探究重金属砷对不同基因型甘蓝型油菜种子萌发期的影响,选育出萌发期耐砷毒的甘蓝型油菜种质资源。本研究利用不同遗传来源的甘蓝型油菜品种(系)为材料,通过对萌发期油菜耐砷性单项指标系数(AC)、平均隶属函数值(ASF值)及砷毒耐性综合评价值(A值)等指标进行相关性分析、主成分分析、逐步回归方程和聚类分析,以获得萌发期耐砷性油菜品种(系),并建立综合耐砷评价体系对材料耐砷性进行鉴定。本试验测定5份供试材料在不同浓度As3+处理下的根长,以不同品种(系)间根长变化差异性为基础,基于方差分析确定最佳处理浓度为15 mg/L;在15 mg/L浓度处理下,发现134份甘蓝型油菜的根长、下胚轴长、鲜重、干重、株高和含水量6个指标均达到差异显著性,并存在不同程度的相关性。研究发现,通过主成分和逐步回归方程分析,根长、下胚轴长和株高可作为有效快速评价甘蓝型油菜萌发期耐砷性的重要指示性状。基于A值聚类分析可将供试种质划分为4类耐性等级,筛选到B472、B358和B4503份材料为强耐砷性品种。本试验将为萌发期甘蓝型油菜高耐砷性分子机理研究和育种材料筛选提供重要的研究基础。

不同芥菜型油菜基因型砷毒耐性研究

采用溶液培养法筛选196个芥菜型油菜基因型的砷(Na3AsO4)毒耐性。结果表明,2mg/L As(以砷酸钠水溶液中的砷离子浓度计)处理条件下,不同基因型油菜的生长和砷累积表现出明显的差异性。调查地上部干重的As/CK(砷处理与对照的比值)和根部的As/CK,发现各基因型变化范围分别为0.48～1.51和0.5～2.06,其变异系数分别为18.5%和30.2%。地上部或根部砷含量的变化范围分别是5.2～168.0mg/kg和117.1～1 544.3mg/kg,其变异系数分别为73.2%和37.5%。依据砷胁迫下油菜的相对干重(As/CK)及砷的含量,筛选出砷排异基因型(生长不受影响,且砷主要累积在根部,茎叶中砷含量较低)15个,砷低吸收基因型(生长不受影响,且茎和叶中砷含量较少)2个,以及砷敏感基因型(生长受严重抑制)5个。

耐砷真菌分离鉴定及对土壤生物有效砷的影响

从砷污染土壤中分离出3 株对砷具有耐受性的真菌菌株,考察了菌株对砷的耐受能力及菌体处理污染土壤时间、菌体投加量对土壤生物砷有效性的影响.经鉴定,3 种菌株分别为球毛壳霉（Chaetomium globosum）、细极链格孢（Alternaria tenuissima）和木糖发酵酵母（Scheffersomyces stipitis）.结果表明：3 种菌株对ρ 为5～100 mg·L^-1的砷具有良好的耐受性,且耐受性从大到小依次为木糖发酵酵母、细极链格孢和球毛壳霉;ρ 为5～10 mg·L^-1的砷对木糖发酵酵母的生长有-定的促进作用,30 d 内土壤生物有效态砷含量与对照相比分别提高137. 2、77. 9 和36. 5 倍;不同浓度菌体对于土壤砷具有不同的作用效果,土壤有效态砷含量随球毛壳霉、细极链格孢和木糖发酵酵母投加量的增加而增加,且两者呈正相关.

砷胁迫下甘蓝型油菜苗期根、下胚轴和鲜重的全基因组关联分析

油菜是修复土壤重金属污染的理想作物,为筛选甘蓝型油菜耐砷性的显著关联单核苷酸多态性位点及相关候选基因,本研究以140份不同来源的甘蓝型油菜自交系为材料,测定和利用油菜60KSNP芯片对正常和砷胁迫条件下的相对根长(RRL)、相对下胚轴长(RHL)和相对鲜重(RFW)进行了全基因组关联分析。结果表明,与RRL、RHL和RFW显著关联的SNP位点分别为15、20和35个,单个SNP位点表型贡献率分别介于13.31%～24.39%、18.04%～33.82%和20.19%～25.06%之间;其中在A02、A07和C02染色体上同时存在与RRL、RHL和RFW显著关联的LD区间。基于油菜基因组信息在LD区间内共筛选到61个可能与砷胁迫相关的候选基因,其中PHT3;3、PHT1;9、GST、OTC5、NRAMP1和ZIP12等与重金属吸收和转运相关。实时荧光定量PCR分析结果表明, PHT3;3和PHT1;9是与甘蓝型油菜砷离子吸收转运相关的重要候选基因。本研究结果对于甘蓝型油菜耐砷胁迫机理的研究、性状的改良具有重要参考价值。

Valence variation of arsenic in bioleaching process of arsenic-bearing gold ore

The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic.The results show that the concentration of As 3+ is larger than that of As 5+ in the lag phase.The concentration of As 3+ decreases in the log phase,and is lower than that of As5 +.HQ-0211 typed bacteria express better resistance for As 3+and As 5+and remain growing when the concentrations of As3 +and As 5+are above 6.0 g/L and 12.0 g/L,respectively.It is found that Fe 3+cannot oxidize As3 +singly as strong oxidant in the leaching system,but can cooperate with pyrite or chalcopyrite to do that.The oxidation of As 3+ is prompted with addition of H2O2.The bacterial activity is improved in favor of bacterial leaching efficiency.NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.

An Investigation on Tolerance and Accumulation of a Facultative Marine Fungus Aspergillus flavus to Pentavalent Arsenic

Tolerance of a facultative marine fungus Aspergillus flavus towards As (V) was tested.Luxuriant growth of the test isolate was observed in culture media with As (V) concentrations of 25 mg L-1 and 50 mg L-1,indicating its tolerance to the metal.Accumulation rate of arsenic was always higher when exposed to As (V) at 50 mg L-1 than at 25 mg L-1.The study reveals Aspergillus flavus as a promising candidate for environmental bioremediation.Arsenic contents (mg g-1) in the fungus when exposed to 50 mg L-1 As (V) were measured as 11.1773,4.0983,and 8.0000 mg g-1 on day 3,6 and 9,respectively.The highest content was observed initially,i.e.on day 3,followed by a decline and a rise again.These results provide baseline information for further explorations regarding the exploitation of the fungus for arsenic removal.

Reversal mechanism of arsenic trioxide in the drug resistance of human gastric cancer cell line SGC7901/ADR

Objective： To investigate the reversal effect of arsenic trioxide （As2O3） on the multidrug resistance of human gastric tumor SGC7901/ADR cell line to adriamycin （ADM） and its reversal mechanisms, Methods： The non-cytotoxic concentration of As2O3 and the sensitivity of SGC7901/ADR cells toADM were detected by MTT assay, The drug concentration and P-gp function of SGC7901/ADR cells were measured with flow cytometry （FCM）, and the impacts of As2O3 on the GST-Π and Topo Ⅱ expressions of SGC7901/ADR cells were analyzed by immunohistochemical method. Results： As2O3 at 0,4 to 0.8 μmol/L concentrations were not significantly cytotoxic to SGC7901/ADR cells, As2O3 at 0.8 μmol/L could improve the sensitivity of SGC7901/ADR cells to ADM via inhibiting P-gp function, down-regulating GST-Π expression and increasing the intracellular accumulation of ADM in SGC7901/ADR cells. Conclusion： As2O3 can reverse partly the drug-resistance of SGC7901/ADR cells to ADM, which may be related with inhibiting the P-gp function and down-regulating GST-Π expression.