Cadmium detoxification processes in the digestive gland of cephalopods in relation to accumulated cadmium concentrations

The high concentrations of cadmium recorded in the digestive gland of cephalopods from various temperate and subpolar waters suggest that these molluscs have developed efficient cadmium detoxification mechanisms. The subcellular distribution of cadmium in the digestive gland cells was investigated in seven cephalopod species from the Bay of Biscay (France) and the Faroe Islands. In most species, cadmium was mainly found in the cytosolic fraction of the digestive gland cells, reaching up to 86% of the total cadmium for the squid Loligo vulgaris from the Bay of Biscay. But species with the highest total level of cadmium showed a higher percentage of cadmium associated to insoluble compounds. The quantification of metallothioneins (MTs) by the polarographic method was performed in order to evaluate the involvement of these proteins in the detoxification of the high amounts of bioaccumulated cadmium. Metallothionein levels in cephalopods ranged form 742 +/- 270 to 3478 +/- 1572 microg/g wet weight. No relationship could be established between total cadmium, cytosolic cadmium and MT levels suggesting the occurrence of other Cd-binding ligands. Although these proteins have not been characterised, as cadmium in the digestive gland of cephalopods is mainly associated with soluble ligands, a high potential transfer to predators can be predicted.     

Oxygen radicals production and actin filament disruption in bivalve haemocytes treated with benzo(a)pyrene

Haemocytes play an essential role in the internal defence of molluscs. It has been reported that organic xenobiotics commonly found as pollutants in the marine environment impair defence capabilities of haemocytes. The purpose of the present study was to investigate the effects of benzo(a)pyrene [B(a)P] on the integrity of the actin cytoskeleton and on endocytosis in haemocytes and to see if these effects are related to generation of reactive oxygen species. Haemocytes were exposed in vitro to B(a)P (0.5-40 microg/ml) for 1 h. Cell viability (using 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide or XTT assay) indicated that selected doses were sublethal. Uptake of neutral red was significantly decreased in a dose-dependent manner in B(a)P-treated haemocytes. Distribution of actin filaments, labeled with rhodamine-conjugated phalloidin, was altered in haemocytes treated with 20 or 40 microg/ml B(a)P. These effects could be related to an increased production of superoxide anion during B(a)P metabolism, as detected by the nitroblue tetrazolium (NBT) reduction assay in haemocytes treated with > or = 10 microg/ml B(a)P.     

俄罗斯内生金矿床勘查的若干问题 ——兼论俄罗斯库顿金矿类型与勘探程度

俄罗斯为世界上六大产金国之一, 金矿床勘查规范独具特点。通过俄联邦自然资源部颁布的《矿床储量与固体矿产预测资源量分类》、《金矿床储量分类方法指南》与中国国土资源部颁布的《岩金矿地质勘查规范》的对比, 剖析中俄两国规范内容的异同。     

Discovery of the Jiawengmen Stromatolite Assemblage in the Southern Belt of Eastern Kunlun, NW China and Its Significance

1 Introduction The stromatolites of the Jiawengmen area in the southern belt of the Eastern Kunlun orogen were initially interpreted as vortex structures by the Regional Geological Survey Team, Qinghai Bureau of Geology and Mineral Resources in 1973; these samples were then identified as algal fossils of Sinian age by the Nanjing Institute of Geology and Paleontology (Qinghai Bureau of Geology and Mineral Resources, 1973). In 1994, Chen and Luo (1998) discovered some stromatolites, i…     

Changes in Soil Salinity in the Ekhiin-Gol Oasis (Mongolia) According to Monitoring Data of 1977 and 2001

IntroductionNatural oases in the Gobi Desert arespecific ecosystems forming in the zones offresh(or slightly saline)groundwater dischargeconfined to tectonic faults[1].Until recently,theirenvironmental peculiarities remained poorlystudied.Before the 1980s,the only data on thenatural oases in the Transaltai Gobi and theirvegetation conditions were published by LavrenkoandYunatov[2].More ample and versatile data on the oasesecosystems were obtained by the Soviet-MongolianBiological Expeditio…     

Simplified approach for design of raft foundations against fault rupture. Part Ⅰ： free-field

Over the past few decades, earthquake engineering research mainly focused on the effects of strong seismic shaking. After the 1999 earthquakes in Turkey and Taiwan, and thanks to numerous cases where fault rupture caused substantial damage to structures, the importance of faulting-induced deformation has re-emerged. This paper, along with its companion （Part Ⅱ）, exploits parametric results of finite element analyses and centrifuge model testing in developing a four-step semi-analytical approach for analysis of dip-slip （normal and thrust） fault rupture propagation through sand, its emergence on the ground surface, and its interaction with raft foundations. The present paper （Part Ⅰ） focuses on the effects of faulting in the absence of a structure （i.e., in the free-field）. The semi-analytical approach comprises two-steps： the first deals with the rupture path and the estimation of the location of fault outcropping, and the second with the tectonically- induced displacement profile at the ground surface. In both cases, simple mechanical analogues are used to derive simplified semi-analytical expressions. Centrifuge model test data, in combination with parametric results from nonlinear finite element analyses, are utilized for model calibration. The derived semi-analytical expressions are shown to compare reasonably well with more rigorous experimental and theoretical data, thus providing a useful tool for a first estimation of near-fault seismic hazard.     

Effects of tributyltin at concentrations below ambient levels in seawater on Caprella danilevskii (Crustacea: Amphipoda: Caprellidae)

Hatched juveniles of Caprella danilevskii (Crustacea: Amphipoda) were exposed to one of two concentrations of tributyltin (TBT) (1.1 and 10.7 ng TBTL(-1)) for 49 d at 20 degrees C. These concentrations are near or below ambient levels in seawater. In both treatments and control, the survival rate was 100% at maturation, and >85% at the end of the experiments. Females reached maturation at 20 (median) to 21.5d at instar VII, and repeated spawning 4-5 times during the experiment. The total number of juveniles per female decreased significantly from 39.5 in the control to 24.5 and 17.5 in 1.1 ng L(-1) and 10.7 ng L(-1) treatments, respectively. An earlier study reported that as the TBT concentration in seawater increased from a 0-10 ng L(-1) regime to a 10-20 ng L(-1) regime, the number of stations where Caprella spp. could be collected decreased along the coast of the Seto Inland Sea, of Japan. Thus, the present study indicates the possibility that the extremely low concentration of TBT measured in Japanese waters after 2000 lead to a reduction in reproductive success of Caprella spp.     

地幔中记录的地球历史

地幔中惰性气体的同位素组成被认为是以下两个过程的结果 :太阳系形成期间不同来源核素的并入 ;地球演化期间以固定速率衰减或累积放射成因组分。如果这个假设正确 ,那么惰性气体同位素的测量将能建立地球生成和演化的模型。实际上 ,地球大气与星际物质的同位素比率极其不同。因此 ,如果在地球历史早期或设想初始地幔组成变化的时间里 ,地球大气的惰性气体并入了地幔 ,关于地幔中非放射成因惰性气体主要反映的是类太阳组成还是类大气组成仍存很大争论。为了解决这一问题 ,Ｔｒｉｅｌｏｆｆ等人用高精度质谱仪分析了取自Ｌｏｉｈｉ、夏威夷和…     

极区电离层对IMF Bz 4次快速转向的响应——EISCAT/ESR雷达观测

利用EISCAT VHF和EISCAT Svalbard（ESR）雷达观测数据,对2003年2月12日IMF B_z分量4次快速方向转换期间,极区电离层,尤其是极尖/极隙区的响应特征进行了分析研究.随着IMF B_z方向的多次快速变化,地面雷达观测到极尖/极隙区所在位置随着开放-闭合磁力线边界在纬度方向上来回移动.在此期间,极区电离层等离子体水平对流多次反向,表现出与IMF B_z分量强的负相关性.进一步分析表明：极区磁层-电离层系统在日侧对IMF极性变化的平均响应时间约为3 min.