The effect of source area and atmospheric transport on mineral aerosol collected over the North Pacific Ocean

Aerosol samples collected on two North Pacific cruises were analyzed for rock-magnetic properties, grain size and <2 μm and 2–20 μm mineralogy. These sedimentological results were compared with isentropic air mass trajectories in order to study the effects of source region and atmospheric transport on the mineral aerosol. The results indicate that there are differences in the aerosol composition and grain size for two broad source regions. Aerosols which originate from west of the Pacific are characterized by abundant, fine-grained aerosol, which has a high coercivity magnetic composition, and is relatively enriched in kaolinite. Aerosols originating from continents to the north and east of the Pacific basin are much less abundant, contain coarse-grained material with a low coercivity magnetic component, and the mineralogy is relatively enriched in plagioclase. Comparison of the mineral aerosol from Asia with atmospheric transport time indicated that the concentration of the mineral aerosol decreases with increasing transport time. The mineral aerosol is compositionally fractionated as it moves away from the continental source region, with a relative decrease in the primary minerals quartz and plagioclase and an increase in the smectite, illite and chlorite concentration with increasing transport time.     

Increased toxicity of benzo(a)pyrene-7,8-dihydrodiol in the presence of polychlorobiphenylols

Benzo(a)pyrene (BaP) and polychlorinated biphenyls (PCBs) often co-exist in contaminated environments. Polychlorobiphenylols (OH-PCBs), formed by CYP-dependent monooxygenation of PCBs, are potent inhibitors of the glucuronidation of hydroxylated BaP metabolites. We hypothesized that OH-PCBs could drive the biotransformation of (-)BaP-7,8-dihydrodiol (BaP-7, 8-D) away from detoxication and towards formation of the reactive metabolite. A mixture of five OH-PCBs with 4-6 Cl atoms was infused into isolated, perfused, biliary intact livers (n=3 fish) removed from 3-methylcholanthrene-induced channel catfish. Controls (n=3) were infused with vehicle. Subsequently, [3H]-BaP-7, 8-D was infused into each liver and bile was collected for 1 h. The livers were taken for analysis of metabolites and DNA adducts. Induction status was confirmed by EROD assay. Bile was analyzed for metabolites. It was found that preinfusion of the mixture of OH-PCBs reduced the extent of glucuronidation of BaP-7, 8-D and increased the formation of DNA adducts 5-fold over controls. GSH conjugates, tetrols and triols were increased in the OH-PCB-infused fish, providing further support for our hypothesis that if the glucuronidation were inhibited, CYP-dependent activation would increase. These studies suggest a mechanism for synergy of toxicity of PAH and PCBs.     

Identification of transcriptional effects of ethynyl oestradiol in male plaice (Pleuronectes platessa) by suppression subtractive hybridisation and a nylon macroarray

Suppression subtractive hybridisation (SSH) was used to generate cDNA libraries representing genes differentially expressed in response to ethynyl oestradiol (EE2) exposure in liver from male plaice (Pleuronectes platessa) previously analysed for vitellogenin (VTG) induction. Characterisation of the cDNA clones identified many as VTG (2 genes) and zona radiata proteins (ZRP) (3 genes), but 40 encoded other proteins, with more than half cryptic. Further analysis identified 85 non-redundant clones suitable for array on nylon membrane. Radiolabelled cDNAs were prepared from hepatic mRNA from EE2 treated plaice (0 and 21 days) and hybridised with the arrayed clones. Analysis of the data showed that 11/17 novel, 21/22 VTG, 13/14 ZRP, 2/2 liver aspartic proteinase (LAP) and 8/10 other mRNAs were up-regulated by EE2 exposure.     

Identification of transcriptional effects of ethynyl oestradiol in male plaice (Pleuronectes platessa) by suppression subtractive hybridisation and a nylon macroarray

Suppression subtractive hybridisation (SSH) was used to generate cDNA libraries representing genes differentially expressed in response to ethynyl oestradiol (EE2) exposure in liver from male plaice (Pleuronectes platessa) previously analysed for vitellogenin (VTG) induction. Characterisation of the cDNA clones identified many as VTG (2 genes) and zona radiata proteins (ZRP) (3 genes), but 40 encoded other proteins, with more than half cryptic. Further analysis identified 85 non-redundant clones suitable for array on nylon membrane. Radiolabelled cDNAs were prepared from hepatic mRNA from EE2 treated plaice (0 and 21 days) and hybridised with the arrayed clones. Analysis of the data showed that 11/17 novel, 21/22 VTG, 13/14 ZRP, 2/2 liver aspartic proteinase (LAP) and 8/10 other mRNAs were up-regulated by EE2 exposure.     

Effect of in vivo cadmium exposure on the respiratory burst of Marine Fish (Limanda limanda L.) phagocytes

Following the in vivo exposure of dab (Limanda limanda L.) to cadmium chloride, kidney phagocytes were collected and their respiratory burst measured in vitro using chemiluminescence. Fish were exposed to mean measured concentrations of 1.3, 2.7 and 5.5 mg Cd litre⁻¹ (as total cadmium ion) for a total of nine weeks, followed by a three week depuration period in clean sea water. Compared with control fish, the respiratory burst of kidney phagocytes from dab sampled after six weeks was significantly reduced in the 2.7 and 5.5 mg Cd litre⁻¹ treatments (Steel's test, p < 0.05). Significant reductions were observed in the respiratory burst of phagocytes from all cadmium exposed fish compared with control fish after nine weeks (Steel's test, p < 0.05). After a further three week depuration period in clean sea water, the respiratory burst of phagocytes from fish previously exposed to 1.3 and 2.7 mg Cd litre⁻¹ were still significantly less than in the control group (Steel's test, p < 0.05). Muscle tissue cadmium concentrations were also analysed, although there was no clear relationship between the muscle total cadmium levels and kidney phagocyte chemiluminescence. The results are discussed with respect to the possible mechanism(s) of cadmium immunotoxicity in dab and recommendations made for future work.     

Kinetics of vitellogenin protein and mRNA induction and depuration in fish following laboratory and environmental exposure to oestrogens

Plaice, flounder and sand goby were exposed to ethynylestradiol (EE2) for 21 days and then followed for up to 31 days after removal of the oestrogen. Plasma vitellogenin (VTG) and hepatic VTG mRNA were determined in groups of fish sampled during the induction and post-exposure phases. VTG mRNA increased slightly earlier than plasma protein, but both reached maxima by 21 days. In contrast, VTG mRNA decayed much more rapidly than protein after EE2 exposure was terminated (typical values t(1/2) mRNA 3 days, protein 15-30 days). Vitellogenin and VTG mRNA thus measure different temporal events and this is illustrated by field data of male flounder in which both parameters have been determined. Few fish show co-ordinate increased VTG mRNA and vitellogenin but rather more fish have increased vitellogenin. Low level increases of VTG mRNA (5 X) is observed in some fish without increased vitellogenin and this may represent polymorphic differences between individual fish.     

Evolutionary connections of biological kingdoms based on protein and nucleic acid sequence evidence

Evolutionary trees are derived based on nucleic acid and protein sequences and the methods of numerical taxonomy. From 5S ribosomal RNA sequences, molecules that participate in protein synthesis, the order of branching of many prokaryote species and the nuclear and organellar components of eukaryote species are inferred. All oxygen-evolving forms, including the chloroplasts and blue-green algae, are to be found on a single branch; the mitochondria are found with the Rhodospirillaceae, nonsulfur photosynthetic bacteria; and the eukaryote cytoplasmic components are found with the archae-bacteria, including Thermoplasma and Sulfolobus. This tree clearly supports the symbiotic origin of the eukaryote organelles. There is much redundant information available from c-type cytochromes, cytochromes c′, 4Fe-4S ferredoxins and 5.8S rRNA molecules. A gene duplication of ferredoxin, probably predating all of the species divergences, permitted us to infer an ancestral molecule that can be placed on the tree to give the base. The heterotrophic anaerobes have a sequence most resembling the ancestral sequence, suggesting that the ancestor may have been a heterotroph. Ten prokaryote species occur on both the c-type and the c′-type cytochrome trees. There is only one inconsistency in the topologies of the two trees, which may reflect a gene transfer among prokaryotes confirming that, for these genes of fundamental importance, gene transfer followed by acceptance is rare. The eukaryote trees derived from 5S and 5.8S rRNA suggest that the earliest eukaryotes were unicellular and that the multicellular forms of plants, animals, fungi and slime molds arose independently.     

Water flow and the vertical distribution of meiofauna: A flume experiment

Laboratory experiments were conducted in a recirculating saltwater flume to determine if flow influences the vertical distribution of meiofauna within fine cohesive sediments. Replicate flume boxcores collected from a nonvegetated mudflat were exposed to either a no flow or a flow experimental treatment. After 3 h in the flume, the boxcores were sampled by taking smaller sediment cores and sectioning these cores vertically in 2-mm intervals. There was no statistical difference in the number of copepods (adults, copepodites, and nauplii) in the top 2mm of sediment in flow vs. no flow treatments. The number of nematodes and foraminiferans within the top 2 mm of sediment was significantly lower in the flow treatments than in the no flow treatments. Downward migrations may decrease the susceptibility of these fauna to passive erosion by tidal currents.     

Sensitivity of cool-temperate forests and their fossil pollen record to rapid temperature change

Simulations of cool-temperate forest growth in response to climatic change using the JABOWA computer model show that a decrease of 600 growing degree-days (equivalent to a 2°C decrease in mean annual temperature) causes red spruce (Picea rubens) to replace sugar maple (Acer saccharum) as the dominant tree. These changes are delayed 100–200 yr after the climatic cooling, producing gradual forest changes in response to abrupt temperature changes, and reducing the amplitude of response to brief climatic events. Soils and disturbances affect the speed and magnitude of forest response. The delayed responses are caused by the difference in sensitivity of adult trees and younger stages. The length of the delay depends on the life history characteristics of the dominant species. Delayed responses imply that fossil pollen deposits, even if they faithfully record the abundances of trees in forests, may not be able to resolve climatic changes within 100–200 yr, or to record very brief climatic events. This explains why pollen deposits do not as yet show responses to climatic changes during the past 100 yr. Only the Little Ice Age, which lasted several centuries, caused sufficient forest change to be recorded in fossil pollen, and only at certain sites.