Biogeochemical characteristics of the Hetai goldfield, Guangdong Province, China     

Li Miao  Ruisong Xu  Yueliang Ma  Jinhong Xu  Jie Wang  Rui Cai  Yu Chen   《Journal of Geochemical Exploration》2008,96(1):43-52

In the Hetai goldfield, Guangdong Province, China, samples including rocks, soils and leaves of four plants (Pinus massoniana, Rhodomyrms tomenlosa, D. linearis var. dichotoma and Embelia laeta) collected from the gold mineralization zone and the background area were analyzed for Au, Ag, Cu, Pb, Zn, Hg, As and physiological parameters. The objective of this investigation is to study the geochemical and biogeochemical characteristics of studied plants, aiming at biogeochemical methods in Au exploration. The goldfield region shows geochemical and biogeochemical anomalies. Abundances of Au in rocks, soils, plants and the leaf pigments in the mineralized area are much higher than those in the surrounding region. The plants display unhealthy physiological and ecological characteristics in the Hetai goldfield area. The cell structures of the goldfield plants were anomalous and aberrant, and there were many nano-metal particles diffused in mitochondria and chloroplasts. Macro- and microscopic evidences of the vegetation in the goldfield areas are distinctly different from the background regions. The strongly anomalies in responses to Au are profound in further geochemical and botanic exploration studies.  相似文献   

中国对虾染色体制备及染色体形态的研究   总被引：6，自引：2，他引：6  

刘萍  麦明  孔杰  王清印  杨丛海 《海洋科学》1994,18(1):33-37

以中国对虾原肠期胚胎为材料，采用整体低渗法和管渗法均制备了染色体。通过比较发现，管渗法制备的染色体比整体低渗法的形态好。本文对制备中国对虾染色体技术方面的问题进行了探讨。通过作者的观察，了解到中国对虾染色体徐正常特征外，还存在较特别的形态特征，如主缢痕增强，次缢痕变化，同源配对等。并对产生这些形态特征的原因进行了解释。  相似文献   

Susceptibility to genetic damage and cell types in Mediterranean mussels   总被引：2，自引：0，他引：2  

Dolcetti L  Venier P 《Marine environmental research》2002,54(3-5):487-491

Micronucleus (MN) frequency is generally accepted as a marker of chromosomal damage and has been studied in a variety of cells and species. In previous work, we detected significant dose-related MN increases in the epithelial-like gill cells and agranular haemocytes of Mytilus galloprovincialis treated with benzo[a]pyrene, a well-known mutagenic pollutant. In addition, we have studied micronuclei and other nuclear abnormalities in mussels collected from the Venice lagoon (Italy). Frequency changes, possibly related to genotoxic/toxic stress, in both granular and micronucleated cells from gills and haemolymph, were detected. Environmental data suggest the effect of genotoxic pollutants and the importance of cell replication in the interpretation of micronucleus frequencies.  相似文献   

Diet restriction induced autophagy: a lysosomal protective system against oxidative- and pollutant-stress and cell injury   总被引：1，自引：0，他引：1  

Moore MN 《Marine environmental research》2004,58(2-5):603-607

Nutrient deprivation or dietary restriction (DR) confers protection against ageing and stress in many animals and induced lysosomal autophagy is part of this mechanism. The effects of dietary restriction on the toxicity of copper and the polycyclic aromatic hydrocarbon phenanthrene have been investigated in the common marine mussel Mytilus edulis. The findings show that DR-induced autophagy facilitates the recovery of the digestive gland (i.e., molluscan liver analogue) from cell injury caused by both copper and phenanthrene. It is inferred that DR-induced autophagy and lysosomal proteolysis results in improved cellular "housekeeping" through the more efficient removal of oxidatively and pollutant damaged proteins (e.g., protein carbonyls, protein adducts, etc.) and that this contributes to stress resistance.  相似文献   

Effects of organochlorine compounds on cytochrome P450 aromatase activity in an immortal sea turtle cell line     

Keller JM  McClellan-Green P 《Marine environmental research》2004,58(2-5):347-351

Many classes of environmental contaminants affect the reproductive function of animals through interactions with the endocrine system. The primary components affected by endocrine active compounds (EACs) are the steroid receptors and the enzymes responsible for steroidogenesis. This study sought to develop an in vitro model for assessing EAC effects in sea turtles by examining their ability to alter cytochrome P450 aromatase (CYP19) activity. Aromatase is the enzyme responsible for the conversion of testosterone to estradiol. This enzyme is critical in the sexual differentiation of reptiles which demonstrate temperature-dependent sex determination. An immortal testis cell line GST-TS from a green sea turtle was grown in culture at 30 degrees C in RPMI 1640 media. The cells were exposed to three known aromatase inducers; dexamethasone (Dex), 8Br-cyclic AMP, or human chronic gonadotropin (HCG) and one aromatase inhibitor 4-androstenol-dione (4-OHA). In addition, the GST-TS cells were exposed to 0.1-30 microM atrazine and 3-100 microM 4,4'-DDE. The inducing compounds that have been shown to increase aromatase activity in other systems failed to induce aromatase activity in the GST-TS cells, yet exposure to the inhibiting compound, 4-OHA, did result in a significant reduction. Atrazine (0.1, 1.0 and 10 microM) significantly induced aromatase activity following a 24 h exposure, and 4,4'-DDE inhibited the activity but only at cytotoxic concentrations (100 microM). Based on these results, this in vitro model can be useful in examining the endocrine effects of EACs in sea turtles.  相似文献   

Powder factors in asymmetric blast patterns     

A. T. Spathis 《Fragblast: International Journal for Blasting and Fragmentation》2006,10(3):97-109

A cell powder factor defines the local powder factor in a simple geometric procedure that accounts for the charge in each blast hole and the triangulation formed by blast hole collars in a blast pattern. In the case of asymmetric blast patterns, the cell powder factor deviates from the global powder factor. Poor drilling of blast hole collars produces significant variation in the cell powder factor, more so, than does poor blast hole charging. The cell powder factor does not account for timing within a blast and does not easily handle non-parallel blast hole configurations. The cell powder factor is best used as a design or audit tool before blast holes are loaded. It gives the opportunity to correct for poor drilling and/or poor charging practices prior to firing a blast.  相似文献   

空间信息网格中动态复制策略的研究     

谢储晖  郭达志 《华东地质学院学报》2005,28(2):179-183

空间信息网格项目数据量大，用户遍及各地，对数据文件的请求延时大、占大量带宽。复制可以节省带宽、减少时延、均衡负载、改善系统可靠性。采用动态复制技术可以使用户有效地获得所需的数据。详细地论述了动态复制策略以及空间信息网格中的复制管理机制、复制服务流程和具体实施。  相似文献   

绿柱石与硅铍石原位结晶实验研究     

王娴  李建康  丁欣  张德会 《地质论评》2016,62(S1):407-408

绿柱石与硅铍石均为铍矿物家族中的主要成员,是重要的工业铍矿物,利用背散射和电子探针研究矿物特性时,常可见两者共生或发生交代的现象（饶灿,2009;Reyf, 2008; Evensen, 1999）,其结晶条件对于成矿环境与成矿机制均具有重要的指示意义。前人已进行了关于绿柱石,硅铍石等铍矿物稳定性的实验研究,但研究多采用高温淬火的高温高压实验装置,误差大,且无法原位观测矿物结晶习性（王振杰, 1992;Sirbescu et al., 2009）,本文利用热液金刚石压腔,原位观测了绿柱石与硅铍石的结晶过程,得到了它们结晶的温压条件及结晶习性。  相似文献   

Temporal replication of the national land cover database using active machine learning     

Galen J. Maclaurin 《地理信息系统科学与遥感》2016,53(6):759-777

Regional and national level land cover datasets, such as the National Land Cover Database (NLCD) in the United States, have become an important resource in physical and social science research. Updates to the NLCD have been conducted every 5 years since 2001; however, the procedure for producing a new release is labor-intensive and time-consuming, taking 3 or 4 years to complete. Furthermore, in most countries very few, if any, such releases exist, and thus there is high demand for efficient production of land cover data at different points in time. In this paper, an active machine learning framework for temporal updating (or backcasting) of land cover data is proposed and tested for three study sites covered by the NLCD. The approach employs a maximum entropy classifier to extract information from one Landsat image using the NLCD, and then replicate the classification on a Landsat image for the same geographic extent from a different point in time to create land cover data of similar quality. Results show that this framework can effectively replicate the land cover database in the temporal domain with similar levels of overall and within class agreement when compared against high resolution reference land cover datasets. These results demonstrate that the land cover information encapsulated in the NLCD can effectively be extracted using solely Landsat imagery for replication purposes. The algorithm is fully automated and scalable for applications at landscape and regional scales for multiple points in time.  相似文献   

无线GIS空间数据动态副本管理研究   总被引：2，自引：0，他引：2  

林承达  孟令奎  彭溢 《武汉大学学报(信息科学版)》2007,32(3):263-266

针对GIS海量空间数据更新要求，研究了无线网络环境下空间数据传输和存储的副本动态复制与管理技术。通过分析空间数据移动复制服务策略，设计了基于无线网络的动态副本管理系统（DRMS）来实现空间数据的移动动态复制，并研究副本管理模型和副本更新算法，保证了无线网络传输的稳定性。  相似文献