A comparative evaluation of oysters, mussels and sediments as indicators of trace metals in Hong Kong waters

Oysters (Saccostrea glornerata = Crassostrea glornerata Gould) taken from 20 locations revealed considerable contamination of the heavily urbanised Victoria Harbour area by copper and zinc. Data for copper and zinc in sediments, based on samples from 210 sites, confirmed this finding. In addition, mussels (Septifer bilocularis [L.]) were collected twice from 23 locations. Copper concentrations in the mussels were in qualitative agreement with the profiles derived from oyster and sediment investigations. However, the relative enrichment of samples from Victoria Harbour and those from elsewhere was less in mussels than in oysters and sediments, suggesting partial regulation of copper by mussels. Zinc was regulated by the nlussels to a much greater extent, differences in zinc concentration between groups of samples or individual samples belng minimal. No parallelisnl existed between oyster, sediment and mussel results with respect to iron levels in the coastal environment of Hong Kong; presumably, the kinetics of iron differ considerably in the 2 bivalve species. We propose that S. bilocularis is unsuitable as an indicator organism of trace metals due to partial or complete metabolic regulation. Future studies in the tropics should be cognizant of this possibility when employing other previously unstudied bivalve species as bio-indicators.published_or_final_versio

The Sphaleron Rate in SU(N) Gauge Theory

The sphaleron rate is defined as the diffusion constant for topological number NCS = int g^2 F Fdual/32 pi^2. It establishes the rate of equilibration of axial light quark number in QCD and is of interest both in electroweak baryogenesis and possibly in heavy ion collisions. We calculate the weak-coupling behavior of the SU(3) sphaleron rate, as well as making the most sensible extrapolation towards intermediate coupling which we can. We also study the behavior of the sphaleron rate at weak coupling at large Nc.Comment: 18 pages with 3 figure

Spatial variation of trace metals within intertidal beds of native mussels (Mytilus edulis) and non-native Pacific oysters (Crassostrea gigas): implications for the food web?

Abstract Pollution is of increasing concern within coastal regions and the prevalence of invasive species is also rising. Yet the impact of invasive species on the distribution and potential trophic transfer of metals has rarely been examined. Within European intertidal areas, the non-native Pacific oyster (Crassostrea gigas) is becoming established, forming reefs and displacing beds of the native blue mussel (Mytilus edulis). The main hypothesis tested is that the spatial pattern of metal accumulation within intertidal habitats will change should the abundance and distribution of C. gigas continue to increase. A comparative analysis of trace metal content (cadmium, lead, copper and zinc) in both species was carried out at four shores in south-east England. Metal concentrations in bivalve and sediment samples were determined after acid digestion by inductively coupled plasma-optical emission spectrometry. Although results showed variation in the quantities of zinc, copper and lead (mg m-2) in the two bivalve species, differences in shell thickness are also likely to influence the feeding behaviour of predators and intake of metals. The availability and potential for trophic transfer of metals within the coastal food web, should Pacific oysters transform intertidal habitats, is discussed

Do people with risky behaviours participate in biomedical cohort studies?

BACKGROUND: Analysis was undertaken on data from randomly selected participants of a bio-medical cohort study to assess representativeness. The research hypotheses was that there was no difference in participation and non-participations in terms of health-related indicators (smoking, alcohol use, body mass index, physical activity, blood pressure and cholesterol readings and overall health status) and selected socio-demographics (age, sex, area of residence, education level, marital status and work status). METHODS: Randomly selected adults were recruited into a bio-medical representative cohort study based in the north western suburbs of the capital of South Australia – Adealide. Comparison data was obtained from cross-sectional surveys of randomly selected adults in the same age range and in the same region. The cohort participants were 4060 randomly selected adults (18+ years). RESULTS: There were no major differences between study participants and the comparison population in terms of current smoking status, body mass index, physical activity, overall health status and proportions with current high blood pressure and cholesterol readings. Significantly more people who reported a medium to very high alcohol risk participated in the study. There were some demographic differences with study participants more likely to be in the middle level of household income and education level. CONCLUSION: People with risky behaviours participated in this health study in the same proportions as people without these risk factors

Behavioural and Physiological Responses of Gammarus pulex Exposed to Cadmium and Arsenate at Three Temperatures: Individual and Combined Effects

This study aimed at investigating both the individual and combined effects of cadmium (Cd) and arsenate (AsV) on the physiology and behaviour of the Crustacean Gammarus pulex at three temperatures (5, 10 and15°C). G. pulex was exposed during 96 h to (i) two [Cd] alone, (ii) two [AsV] alone, and (iii) four combinations of [Cd] and [AsV] to obtain a complete factorial plane. After exposure, survival, [AsV] or [Cd] in body tissues, behavioural (ventilatory and locomotor activities) and physiological responses (iono-regulation of [Na+] and [Cl−] in haemolymph) were examined. The interactive effects (antagonistic, additive or synergistic) of binary mixtures were evaluated for each tested temperature using a predictive model for the theoretically expected interactive effect of chemicals. In single metal exposure, both the internal metal concentration in body tissues and the mortality rate increased along metallic gradient concentration. Cd alone significantly impaired both [Na+] and [Cl−] while AsV alone had a weak impact only on [Cl−]. The behavioural responses of G. pulex declined with increasing metal concentration suggesting a reallocation of energy from behavioural responses to maintenance functions. The interaction between AsV and Cd was considered as ‘additive’ for all the tested binary mixtures and temperatures (except for the lowest combination at 10°C considered as “antagonistic”). In binary mixtures, the decrease in both ventilatory and locomotor activities and the decline in haemolymphatic [Cl−] were amplified when respectively compared to those observed with the same concentrations of AsV or Cd alone. However, the presence of AsV decreased the haemolymphatic [Na+] loss when G. pulex was exposed to the lowest Cd concentration. Finally, the observed physiological and behavioural effects (except ventilation) in G. pulex exposed to AsV and/or Cd were exacerbated under the highest temperature. The discussion encompasses both the toxicity mechanisms of these metals and their interaction with rising temperature

Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Staying in touch with the endocytic network: the importance of contacts for cholesterol transport

Cholesterol homeostasis is critical for cell function and human health. Cholesterol is heterogeneously distributed among cellular membranes, with the redistribution of endocytosed dietary cholesterol playing a pivotal role in the regulation of cholesterol homeostasis. While gaps remain in our understanding of intracellular dietary cholesterol transport, a highly complex network of pathways is starting to emerge, often involving inter‐dependent vesicular and non‐vesicular transport mechanisms. The last decade has seen a surge in interest in non‐vesicular transport and inter‐organellar communication at membrane contact sites. By providing platforms for protein interactions, signalling events, lipid exchange and calcium flux, membrane contact sites (MCS) are now appreciated as controlling the fate of large amounts of lipid and play central roles in the regulation and co‐ordination of endocytic trafficking. Here, we review the role of MCS in multiple pathways for cholesterol export from the endocytic pathway and highlight the intriguing interplay between vesicular and non‐vesicular transport mechanisms and relationship with neurodegenerative disease