Environmental genotoxicity and cytotoxicity in the offshore zones of the Baltic and the North Seas

Micronuclei (MN), nuclear buds (NB) and fragmented-apoptotic cells (FA) were analyzed in mature peripheral blood and immature cephalic kidney erythrocytes of flounder (Platichthys flesus), dab (Limanda limanda) and cod (Gadus morhua) from 12 offshore sites in the Baltic Sea (479 specimens) and 11 sites in the North Sea (291 specimens), which were collected during three research vessel cruises in December 2002, 2003 and in September 2004. The highest levels of environmental genotoxicity (frequencies of MN up to 0.5‰, NB – up to 0.75‰) and cytotoxicity (FA – up to 0.53‰) were observed in flatfishes from areas close to oil and gas platforms in the North Sea and in zones related to the extensive shipping and potentially influenced by contamination from large European Rivers (Elbe, Vistula, Oder). In dab from the offshore zones of the North Sea, the levels of nuclear abnormalities were higher as compared to those in dab from the Baltic Sea. Responses in immature kidney erythrocytes were higher than in mature erythrocytes from peripheral blood. MN frequency lower than 0.05‰ (the Baltic Sea) and lower than 0.1‰ (the North Sea) could be suspected as a reference level in the peripheral blood erythrocytes of flatfish.     

化学诱变剂在实验海洋食物链中的流动以及遗传毒性的检测——镉在褐指藻→中国对虾→欧氏六线鱼实验食物链中的传递

于1989年3月—1989年9月,利用极谱测定法研究了无机诱变剂Cd在3级实验食物(链从褐指藻经中国对虾至欧氏六线鱼)中的传递,并对积累Cd的中国对虾和欧氏六线鱼肌肉和内脏灰样进行了紫露草微核测定。结果表明,Cd浓度在传递中依次减少;经过6d喂食,Cd从褐指藻到中国对虾的传递比例为66.6％;经过7d喂食,Cd从中国对虾到欧氏六线鱼的传递比例为29.9％。t测验发现,处理组对虾内脏灰样与肌肉灰样之间诱变性差异显著(P<0.01);处理组与对照组对虾内脏灰样之间的诱变性差异亦显著(P<0.01)。     

镉在褐指藻～海湾扇贝食物链中的传递以及遗传毒性的检测

为了探究化学诱变剂镉在海洋食物链中的传递规律及其与人类健康的关系,作者设计了从海洋浮游藻类——褐指藻(Phaeodactylum tricornutum Bohlin)～海湾扇贝(Argopecten irradians Lamarck)的实验室食物链,采用极谱分析方法研究了镉的传递,并对贝肉(软体组织)灰样进行了紫露草微核(Trad-MCN)测定,结果:(1)经过6d的传递实验,处理组与对照组贝肉中镉的浓度均未超过对应组褐指藻中镉的浓度;经过这条食物链的传递,镉的浓度减少。(2)通过t测验发现,两个高浓度处理组与对照组贝肉灰样之间的诱变性差异显著(P<0.001与P<0.005)。t值的大小与镉的浓度具有一致性关系,说明镉的浓度越大,诱变性越强。     

Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments

Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments.     

Ras gene in marine mussels: a molecular level response to petrochemical exposure

Mussels are susceptible to numerous toxicants and are often employed as bioindicators. This study investigated the status of the ras proto-oncogene in Mytilus galloprovincialis following petrochemical exposure. A M. galloprovincialis homologue of the vertebrate ras gene was isolated, showing conserved sequence in regions of functional importance and a high incidence of polymorphic variation. Mutational damage was investigated in mussels chronically exposed to the water-accommodated fraction of #4 fuel-oil (WAF), and in mussels collected along the NW coast of Portugal in sites with different levels of petrochemical contamination. A ras gene point mutation was identified in the codon 35 of one individual exposed to 12.5% WAF. No mutations were detected in mussels from the WAF control or environmental samples. This represents the first report of a ras gene mutation, experimentally-induced by petrochemical exposure, in an invertebrate species.     

Nuclear Morphology and Lysosomal Stability of Molluskan Hemocytes as Possible Biomarkers of Arsenic Toxicity

The frequency of nuclear aberrations and neutral red retention time of hemocytes in the mollusk Lamellidens marginalis were recorded under exposure to sublethal concentrations of sodium arsenite in order to examine the sensitivity and effectiveness of these inexpensive assays for screening the toxicity of As³⁺ in a freshwater ecosystem. A dose and time dependent increase in the density of micronucleated and binucleated hemocytes and gill cells was indicative of the pronounced genotoxic effect of arsenic on this animal. The disruption of intrahemocyte homeostasis imposed by this natural toxicant was evident from a dose and time dependent reduction in the lysosomal stability of the hemocytes of the animal. The tested parameters are indicative of arsenic toxicity in L. marginalis in the freshwater systems of the arsenic affected geographical areas of West Bengal, India.