重金属Cu、Pb对泥鳅(Misgurnus anguillicaudatus)卵细胞凋亡及DNA损伤的SCGE试验

采用室内暴露试验方法,以单细胞凝胶电泳技术(SCGE)检测,研究了Cu、Pb不同浓度梯度与不同暴露时间联合染毒对泥鳅卵细胞DNA的损伤.结果表明,各Cu、Pb浓度组DNA平均迁移长度增加,与阴性对照组比较差异有显著性(P＜0.05).此外,随着Cu、Pb染毒剂量的增加,各试验组DNA的平均迁移长度逐渐增加,在试验浓度梯度范围内(Cu 0.01mg/L+Pb 0.05mg/L、Cu 0.10mg/L+Pb 0.50mg/L、Cu 0.25mg/L+Pb 0.75mg/L),存在较为显著的剂量-效应关系(P＜0.05),但未见明显的时间-效应关系(P＞0.05).Cu、Pb可引起泥鳅卵细胞凋亡和DNA损伤,卵细胞的不同损伤水平可望作为较为理想的水环境基因毒性指标.     

单细胞凝胶电泳用于检测低温保存的真鲷(Pagrosomus major)精子DNA损伤

应用单细胞凝胶电泳(SCGE)方法,对超低温冷冻保存的真鲷精子DNA的损伤状况进行了检测研究。针对研究对象,在实验过程中对传统的碱性单细胞凝胶电泳在铺胶方法、电泳条件等进行了改进。对精子细胞进行预处理,在碱性电泳液中使核DNA双链解链变性后电泳,EB染色10min后,在荧光显微镜下观察,每次随机观察50个左右的核DNA。结果表明,对荧光显微镜下观察到的精子核按彗尾长度及荧光强度划分等级,出现损伤的精子核DNA的损伤程度主要为轻度损伤和中度损伤,很少见有完全损伤的真鲷精子核。对比真鲷冷冻精液与新鲜精液的精子DNA的损伤状况,表明仅用30%DMSO冷冻精子DNA损伤状况与鲜精差异显著(P>95%),其他冷冻方法保存的精子与鲜精差异不显著(P>95%)。     

Roles of polysaccharide from <Emphasis Type="Italic">Branchiostoma belcheri</Emphasis> in anti-DNA oxidation and anti-tumor activity in S180 mice

In this study, we isolated a polysaccharide from Branchiostoma belcheri (PBB) by enzymatic protein hydrolysis and alcohol precipitation. We investigated the effects of PBB supplementation on DNA oxidation and growth of the transplanted tumor cells Sarcoma (S₁₈₀) in mice. Sixty healthy Kunming mice weighing between 18 and 25 g were randomly assigned to 6 groups, each consisting of 10 animals. All the mice, except for the blank control group, were inoculated with S180 sarcoma cells into the axilla of the left foreleg. PBB was given to mice by gavage at doses of 0 (model control), 25, 50, or 100 mg/kg b.w. in 0.2 ml saline for 30 days. The fifth group of S₁₈₀-mice was given cytoxan (50 mg/kg) by peritoneal injection as a positive control group. The animals had free access to food and water. The mice were sacrificed after the final treatment and blood was quickly collected. Spontaneous and oxidized DNA damage of peripheral lymphocytes induced by H₂O₂ were analyzed by SCGE. O⁶-methyl-guanine (O⁶-MeG) was measured by high-performance capillary zone electrophoresis. The average tumor weights (0.856–1.118 g) of the three PBB groups were significantly lower than that of the model control group (1.836 g) (p<0.05). The tumor inhibition ratios of the PBB groups were 39.1%–53.4% and similar to the cytoxan positive group (57.5%). There were no significant differences in spontaneous DNA damage in peripheral lymphocytes among the groups. The oxidative DNA damage induced by 10 μmol/L H₂O₂ in the 50 and 100 mg/kg b.w. groups were 246.1 AU and 221.7 AU, respectively, both of which were significantly lower than that in the model group (289.0 AU; p<0.05). The plasma concentrations of O⁶-MeG in the 25, 50, and 100 mg/kg supplemented groups were 2.09 μmol/L, 1.86 μmol/L, and 1.63 μmol/L, respectively, all of which were significantly lower than that of the model group (2.67 μmol/L; p<0.05). These results indicated that PBB may have antioxidative activity and thus reduce oxidation-induced DNA damage.     

A framework for economic loss estimation due to seismic transportation network disruption: a spatial computable general equilibrium approach

This paper presents a framework for assessing the economic impact of disruption in transportation that can relate the physical damage to transportation networks to economic losses. A spatial computable general equilibrium (SCGE) model is formulated and then integrated with a transportation model that can estimate the traffic volumes of freight and passengers. Economic equilibrium under a disruption in the transportation network is computed subject to the condition that the adjustment of labor and capital inputs is restricted; the model reflects slow adjustment of these linked to the state of recovery. As a case study, the model reviews the large Niigata-Chuetsu earthquake of 2004. Considering the damage to the transportation infrastructure, the model indicates the extent of the economic losses arising from the earthquake distributed over regions as a consequence of the intra- and interregional trade in a regional economy. The results show that 20% of the indirect losses occur in the Niigata region directly affected by the earthquake, whereas 40% of the total losses are experienced in the Kanto region and non-negligible losses reach rather remote zones of the country such as Okinawa.