Transport Sector and Regional Price Differentials: A SCGE Model for Chinese Provinces

With regression formulas replaced by equilibrium conditions, a spatial CGE model can substantially reduce data requirements. Detailed regional analyses are thus possible in countries where only limited regional statistics are available. While regional price differentials play important roles in multi-regional settings, transport does not receive much attention in existing models. This paper formulates a spatial CGE model that explicitly considers the transport sector and FOB/CIF prices. After describing the model, performance of our model is evaluated by comparing the benchmark equilibrium for China with survey-based regional I-O and interregional I-O tables for 1987. The structure of Chinese economies is summarized using information obtained from the benchmark equilibrium computation. This includes regional and sectoral production distributions and price differentials. The equilibrium for 1997 facilitates discussion of changes in regional economic structures that China has experienced in the decade.

Spatial price equilibrium and the transport sector : a trade-consistent SCGE model

This paper presents a framework for an SCGE model that is compatible with the Armington assumption and explicitly considers transport activities. In the model, the trade coefficient takes the form of a potential function,and the equilibrium market price becomes similar to the price index of varietal goods in the context of new economic geography (NEG). The features of the model are investigated by using the minimal setting, which comprises two non-transport sectors and three regions. Because transport costs are given exogenously to facilitate study of their impacts, commodity prices are also determined relative to them. The model can be described as a system of homogeneous equations, where an output in one region can arbitrarily be determined similarly as a price in the Walrasian equilibrium. The model closure is sensitive to formulation consistency so that homogeneity of the system would be lost by use of an alternative form of trade coefficients.

Well-trained, healthy triathletes experience no adverse health risks regarding oxidative stress and DNA damage by participating in an ultra-endurance event

Also physical exercise in general is accepted to be protective, acute and strenuous exercise has been shown to induce oxidative stress. Enhanced formation of free radicals leads to oxidation of macromolecules and to DNA damage. On the other hand ultra-endurance events which require strenuous exercise are very popular and the number of participants is continuously increasing worldwide. Since only few data exists on Ironman triathletes, who are prototypes of ultra-endurance athletes, this study was aimed at assessing the risk of oxidative stress and DNA damage after finishing a triathlon and to predict a possible health risk. Blood samples of 42 male athletes were taken 2 days before, within 20 min after the race, 1, 5 and 19 days post-race. Oxidative stress marker increased only moderately after the race and returned to baseline after 5 days. Marker of DNA damage measured by the SCGE assay with and without restriction enzymes as well as by the sister chromatid exchange assay did either show no change or deceased within the first day after the race. Due to intake during the race and the release by the cells plasma concentrations of vitamin C and α-tocopherol increased after the event and returned to baseline 1 day after. This study indicates that despite a temporary increase in some oxidative stress markers, there is no persistent oxidative stress and no DNA damage in response to an Ironman triathlon in trained athletes, mainly due to an appropriate antioxidant intake and general protective alterations in the antioxidant defence system.

Anwendung von Fischzellkulturen in der Meeresforschung

A large number of chemical pollutants can be found in the marine environment. So it is necessary to obtain informations about the toxic effects of this contaminant mixtures in general and especially on single cell level. We used an organic extract of a marine sediment from the North Sea to investigate its cyto- and genotoxicity with an in vitro system, the comet assay or single cell gel electrophoresis (SCGE). The comet assay can be applied for estimating genotoxic effects of chemicals on single cell level. First results confirm the sensitivity of this assay and its applicability in assessing genotoxic load in environmental samples. A permant cell line, the EPC (Ephithelioma papulosum cyprini) was used for the experiments. It was possible to demonstrate the suitability of this in vitro test system for assessing genotoxic and cytotoxic effects of marine sediment extracts on EPC cells.

爪哇伪枝藻胞外多糖诱导皮肤癌细胞(A431)凋亡的研究

为探讨爪哇伪枝藻胞外多糖(Extracellular polymeric substances ofScytonema javanicum,EPS)诱导人表皮癌A431细胞凋亡及其对凋亡相关基因caspase-3、bcl-2和bax表达的影响,本实验利用MTT法检测细胞生长抑制情况;HE染色法及透射电镜进行形态学观察;单细胞凝胶电泳法(SCGE/彗星电泳)分析DNA受损情况;免疫组织化学法检测细胞内caspase-3、bcl-2和bax表达水平。结果显示EPS能显著抑制A431细胞增殖,并呈时间和剂量依赖

重金属Cd~(2+)、Pb~(2+)和Zn~(2+)对泥鳅DNA损伤的研究

采用单细胞凝胶电泳技术(SCGE),研究重金属Cd2+、Pb2+、Zn2+在不同暴露时间(1—35d)、单一重金属离子不同暴露浓度(0.05mg/L、0.5mg/L、5.0mg/L)或混合重金属离子(Cd2++Pb2+、Cd2++Zn2+、Pb2++Zn2+、Cd2++Pb2++Zn2+)相同浓度(0.5mg/L)条件下对泥鳅肝胰脏细胞核DNA的损伤作用。以带彗尾核DNA百分率和彗尾长度(TL)与核直径(D)比值为指标,探讨DNA损伤级别与处理浓度间的相关性。结果显示,随着处理时间的延长,带彗尾核DNA百

重离子辐射致肝癌细胞DNA损伤的时间效应初探

以SMMC-7721肝癌细胞为材料,采用单细胞凝胶电泳(Single cell gel electrophoresis,SCGE)实验方法,利用兰州近代物理研究所重离子研究装置(HIRFL)产生的氖离子(80MeV/u20Ne10+),研究重离子对肿瘤细胞DNA的损伤程度随时间的变化情况。结果表明,重离子辐照所致原初损伤与剂量呈线性正相关;继续培养24h内有明显的DNA两次损伤现象。

单细胞电泳观察重离子辐照人肝癌细胞所致DNA损伤

目的　研究重离子对肿瘤细胞DNA的损伤程度 ,为重离子治癌的临床应用积累必要的基础数据。方法　用 80MeV u氖离子射线诱发SMMC 772 1细胞DNA辐射损伤 ,利用单细胞凝胶电泳 (singlecellgelelectrophoresis ,SCGE)实验方法处理细胞 ,并对结果进行统计分析。结果　氖离子辐照以剂量依赖的方式引起SMMC 772 1细胞DNA迁移长度的增加 ,且拖尾长度与剂量呈线性正相关 ;同时 ,拖尾的细胞数 (即损伤的细胞数 )在剂量大于 2Gy时 1 0 0 %细胞损伤。结论　重离子射线对DNA有强致损效应。

重离子引起DNA损伤及其对细胞周期进程的影响

目的：木论文重点研究重离子不同剂量离子辐照后DNA损伤程度的变化，以及进而引起的细胞周期改变等现象。为重离子治癌的临床应用积累必要的基础数据。材料与方法：采用兰州重离子研究装置（HIRFL）加速的碳、氖等重离子辐照体外培养的贴璧肿瘤细胞，以单细胞电泳法（SCGE）检测DNA的损伤程度；以流式细胞技术（FCM）检测细胞的周期改变现象。结果：1．SMMC-7721月干癌细胞经重离子（氖、碳）辐照后，DNA损伤现象明显，表现为单细胞电泳中出现的普遍的拖尾现象（t-test，P<0.001，compared with control。2．80MeV／u 2ONe10＋辐照后立即检测发现：2Gy造成100％的细胞损伤：8Gy照射造成80％的细胞严重损伤：且彗尾拖尾长度随剂量增加早．指数关系增长，仔值为0.99058。3．辐照后12小时，若干不同剂量辐照的样品其彗尾长度趋于相同：如05协、Ic）和ZGy辐照样品的彗尾长度分别为132.3±12.8、132.9±9.5和133.1±11.7μm，24h，时为35.0±3.9、35.5±4.1和48.2±6.Oμm，这说明在一定剂量范围内（0.5-2Gy）的辐照下，随着修复时间的延长，细胞DNA的损伤程度将趋于相同。同时，细胞继续孵育12小时，对于0.55-2Gy辐照组来说DNA的损伤情况是24小时内操作最严重的。4．辐照后24小时，0.5-2Gy辐照组埙份明显修复，略高于对照，但是对于4Gy和SGy辐照组仍带有明显的损伤现魏。簇说眼熏离子辐照（>4Gy）所致DNA报伤的不足修复性。5，DNA的损伤将导致细胞通过一系列调节机制抑制细胞周期的进行，为DNA修复系统提供充足的时间进行DNA修复，从而造成明显的细胞周期阳．滞现琢，这在重离子辐照实验中同样得到证实，尤其是S期、G2／M期阻净带现象非常明显。

DNA分子标记技术在环境污染物检测中的应用

DNA分子标记是DNA分子碱基序列变异的直接反映,利用分子标记物对污染物造成的生物体DNA损伤的检测和定量分析研究是可行的方法。文章主要综述了DNA加合物技术、随机扩增DNA多态性技术(RAPD)、扩增片段长度多态性技术(AFLP)、单细胞凝胶电泳技术(SCGE)及反转录聚合酶链式反应(RT-PCR)的原理及其在环境污染物检测中的应用。该方法具有快速、简便、特异性强的特点,在环境污染物早期诊断和评价方面具有重要意义,已广泛应用于遗传毒理学研究。

Effects of infection of EGH-expressing Escherichia coli on haemocytes in Ciona intestinalis

The effects of infection of EGFP-expressing Escherichia coli on the haemocytes of the ascidian Ciona intestinalis were investigated. The results showed that THC of the infected individuals changed significantly. Hyaline amoebocytes phagocytosed E. coli in 5 min and excreted lysosome particles that attached to the surface of the bacteria. Granular amoebocytes released lots of particles for Immoral immunity while stem-cell-like haemocytes remained intact. With the increase in THC, the stem-cell-like haemocytes showed division and proliferation. A small portion of hyaline amoebocytes was at early apoptosis stage I h after infection and typical apoptosis bodies emerged in granular amoebocytes. A few of the infected haemocytes showed DNA damage using SCGE assay. Flow cytometry analysis revealed an obvious apoptosis peak in infected haemocytes. In conclusion, apoptosis was found to be an important immune response of ascidian haemocytes response to bacterial infection. To our best knowledge, this is the first report of the occurrence of apoptosis of haemocytes in ascidians. (c) 2005 Elsevier B.V. All rights reserved.

真鲷(Pagrosomus major)胚胎冷冻保存损伤机理及冷冻精子遗传物质稳定性研究

本文对真鲷心跳期胚胎对5种常用渗透性抗冻剂（DMSO、甘油、甲醇、丙二醇、乙二醇）和3种非渗透性抗冻剂（PVP、PEG-8000、蔗糖）的耐受性进行了研究。渗透性抗冻剂分6个浓度梯度（5%；10%；15%；20%；25%；30%）和3个时间组（10min；30min；1h）。非渗透性抗冻剂中，PVP、PEG-8000分3个浓度梯度（5%、10%、15%）和2个时间组（10min、30min），蔗糖为4个浓度梯度（5%、10%、15%、20%）和2个时间组（10min、30min）。实验结果表明，在渗透性抗冻剂组中，浓度为5%的处理组的孵化率（>90%）与对照组差异均不显著，随着抗冻剂浓度增大及处理时间的延长，真鲷心跳期胚胎的孵化率显著下降（P<0.05），在最高浓度的最长处理时间中胚胎孵化率均降到了0。总体上，真鲷心跳期胚胎对五种渗透性抗冻剂的耐受性从小到大依次为：甲醇 < 甘油 < 乙二醇 < DMSO < 丙二醇。对影响胚胎孵化率的三个因素（抗冻剂、浓度、时间）进行的因素效应分析结果表明，三种因素对孵化率的影响显著（P<0.05），并且浓度效应 > 时间效应 > 抗冻剂效应。在非渗透性抗冻剂组中，蔗糖组胚胎孵化率未呈显著变化；PVP组随着浓度及时间的增大，孵化率显著下降（P<0.05）；PEG-8000组随着浓度增大孵化率显著下降（P<0.05），但在两个时间组间差异不显著。相同处理情况下PEG-8000对真鲷心跳期胚胎的毒性要小于PVP。因素效应分析比较结果表明仅时间效应不显著，且抗冻剂效应 > 浓度效应 > 时间效应。 对所用各种抗冻剂进行了渗透压测量，实验中使用的渗透性抗冻剂（5%-30%）的渗透压值在959-7980mOsm/kg之间，均高于使用海水的渗透压值（919mOsm/kg）；使用的非渗透性抗冻剂的渗透压值在316-1040mOsm/kg之间，除20%蔗糖渗透压值（1040mOsm/kg）高于海水外，其他非渗透性抗冻剂的渗透压值均要低于海水。对孵化率与相应的溶液渗透压值进行相关回归分析结果表明，渗透性抗冻剂的渗透压与孵化率呈显著的负相关（P<0.05），而非渗透性抗冻剂的渗透压与孵化率相关不显著。渗透性抗冻剂组的回归分析结果表明，二次方程的曲线拟合度最高，得到的回归方程分别为：Y10min = -2×10-8X2 10min - 6×10-5 X 10min + 1.5635 （R2 = 0.713），Y30min= 5×10-8X2 30min－0.0007 X 30min + 2.097（R2 = 0.681），Y1h = 7×10-8X2 1h－0.0008 X 1h+ 2.0397（R2= 0.725）。 在真鲷胚胎对抗冻剂耐受性实验的基础上，挑选五种抗冻剂--10%DMSO、5%甘油、10%甲醇、20%丙二醇、10%乙二醇，浸泡真鲷心跳期胚胎30min后，分别以超速（130℃/min）、快速（20℃/min）、慢速（3℃/min）的速度降温并使用低温显微镜进行观察，依次记录Toif（油球结冰）、Teif（胚胎外部结冰）、Tiif（胚胎内部结冰）等结冰点，Toif值在-9~-23℃之间；Teif值在-21~-35℃之间；Tiif值在-21~-52℃之间。结冰顺序为先油球结冰，然后胚胎外部结冰随之内部马上瞬间变黑形成内部冰晶。随着降温速度的提高，各结冰温度值显著下降。各抗冻剂之间的Teif及Tiif值不同，Toif值之间没有显著差异。对两种玻璃化冷冻方法进行模拟观察，发现胚胎冰晶形成的顺序与非玻璃化过程不同--先内部结冰然后逐渐蔓延至外部形成外部冰晶，而且模拟玻璃化的内部结冰温度Tiif值（-52.56℃）显著（P<0.05）低于使用低浓度的同种抗冻剂超速降温组的Tiif值（-40.11℃）。在快速及慢速降温组中，20%丙二醇组的Tiif要显著的低于其他组（P<0.05）；在超速降温中，甲醇组的Tiif值要显著的低于其他组（P<0.05）。在Tiif小于30℃的实验组中获得形态完整胚胎的比例平均仅有30.77%；在Tiif大于30℃的实验组中获得形态完整胚胎的平均比例高达70.37%，模拟玻璃化组达到100%。各抗冻剂之间，复温后胚胎形态完整率10%甲醇组最高（77.78%）；其次依次为10%乙二醇（66.67%）、20%丙二醇（55.56%）和10%DMSO（55.56%）；5%甘油组最低（11.11%）；推测甲醇的对胚胎的渗透效果要好于其他组。综上推测：使用丙二醇、甲醇作为抗冻剂以及玻璃化冷冻保存方法对真鲷心跳期胚胎超低温保存也许较为合适。 我们对低温保存的真鲷精子核DNA损伤进行了研究以期为下一步胚胎遗传物质稳定性研究提供参考依据。研究方法为单细胞凝胶电泳（SCGE），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lOmin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。经5%、10%、18%、20%、25%、30%DMSO冷冻保存后的精子彗星率分别为33.47％ ± 8.95％; 35.91％ ± 19.44％; 48.95％ ± 8.90％; 43.33％ ± 11.19％; 55.80％ ± 38.94％。鲜精彗星率为31.43 ％ ± 2.68％。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<0.05)。 综上所述，渗透性抗冻剂对胚胎的毒性与其渗透压值呈显著的负相关关系。丙二醇对真鲷心跳期胚胎毒性最小，甲醇较其他抗冻剂能更好的渗透入胚胎；玻璃化方法能显著降低Tiif值并能更好的保持超低温保存后胚胎的形态完整性，因此，使用丙二醇、甲醇作为抗冻剂以及玻璃化冷冻保存方法对真鲷心跳期胚胎超低温保存也许较为合适。常规使用的用于超低温保存真鲷精子的DMSO（浓度<15%）不会对精子核物质稳定性造成明显影响。由于胚胎较精子结构要复杂许多，对于真鲷胚胎损伤机理的研究还有大量工作可以开展。

Effect of ethanol extract of alga Laurencia supplementation on DNA oxidation and alkylation damage in mice

Laurencia terpenoid extract (LET) had been extracted from the red alga Laurencia tristicha. The study is to investigate the effects of LET supplementation on DNA oxidation and alkylation damages in mice. Forty healthy kunming mice weighing between 18g and 25g were randomly assigned into 4 groups, each consisting of ten animals. The mice were orally intubated respectively for 60 days with the designed concentrations of LET (25, 50, 100 mg/kg b.w.) for three exposed groups and salad oil (0.2 ml) for the blank group. Food and water were free for the animals. Mice in the blank and exposed groups were sacrificed after the last treatment and the blood of each animal was quickly taken for further experiments. The spontaneous and oxidized DNA damages of peripheral lymphocytes induced by H2O2 were analysed by SCGE. O-6-Methy-guanine (O-6-MeG) was measured by high performance capillary zone electrophoresis. There was no significantly difference in DNA spontaneous damage on peripheral lymphocytes of all the mice. The oxidative DNA damage in the 50 mg/Kg body weight supplement group are 286AU with the oxidation of 10 mu mol/L H2O2, significantly lower than the blank group 332AU (p<0.05). The contents of O-6-MeG in plasma in the 50mg/kg b.w. and 100mg/kg b.w. supplement group were 1.50 mu mol/L andl.88 mu mol/L, significantly lower than that of the blank group, which was 2.89 mu mol/L(p<0.05). The results from the present study indicated that the LET were rich in terpenoids and safety to be taken orally and it could improve antioxidative and decrease DNA damage effectively.

First in vivo evaluation of the mutagenic effect of Brazilian green propolis by comet assay and micronucleus test

Propolis is a hive product containing chiefly beeswax and plant-derived substances such as resin and volatile compounds. Propolis has been used in various parts of the world as an antiseptic and wound healer since ancient times, and interest in the product has recently increased. Considering the lack of data concerning the in vivo mutagenicity of green propolis, the capacity of this natural product to cause damage to the DNA was evaluated, using the alkaline single-cell gel electrophoresis (SCGE) and micronucleus test, in the peripheral blood cells of mice. The doses tested by gavage were 1000, 1500 and 2000 mg/kg. Micronucleus and SCGE assays showed that green propolis caused an increase in the damage to DNA in the peripheral blood cells of mice. The polychromatic: normochromatic erythrocytes ratio was not statistically different from the negative control. Considering the doses and the results obtained in this study, the acute consumption of green propolis produced some mutagenic effects on the blood cells of mice. (C) 2008 Elsevier Ltd. All rights reserved.

Evaluation of the genotoxic potential of Austroplenckia populnea (Reiss) Lundell chloroform fraction from barkwood extract in rodent cells in vivo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)