Determining the zone of impact of norovirus contamination in shellfish production areas through microbiological monitoring and hydrographic analysis.

Norovirus (NoV) contamination of filter feeding bivalve shellfish is a well-recognised human health threat when shellfish are grown in sewage polluted waters. To date, the identification of high risk zones around sewage discharges in shellfish production areas (SPAs) has not been based on NoV data. This study utilised molecular methods for NoV analysis, combined with hydrographic studies, to determine the relationship between NoV concentrations in shellfish and sewage effluent dilution. Cages with mussels and oysters were placed at different distances downstream of sewage discharges in two coastal sites in England. The shellfish were tested for concentrations of NoV (genogroups I and II) and E. coli. Drogue tracking and dye tracing studies were conducted to quantify the dispersion and dilution of sewage effluent in the SPAs. Significant negative associations were found between both total concentrations of NoV (GI + GII) and E. coli and sewage effluent dilution in the SPAs. The total NoV concentrations predicted by the model at 300:1, 1000:1 and 5000:1 ratios of estuarine water to sewage effluent were 1200; 600; and 200 copies/g, respectively. The estimated area of NoV contamination varied according with local pollution source impacts and hydrographic characteristics. The results help to inform the derivation of sewage discharge buffer zones as a control measure for mitigating risk from human NoV contamination in SPAs.

Rainfall and river flows are predictors for beta-glucuronidase positive Escherichia coil accumulation in mussels and Pacific oysters from the Dart Estuary (England).

Rainfall and river flows are environmental variables influencing the microbial status of bivalve mollusc harvesting areas. This study investigated spatial and temporal relationships between rainfall, river flows and concentrations of Escherichia coli in mussels (Mytilus spp.) and Pacific oysters (C. gigas) from three harvesting areas in the Dart Estuary over the period 1996-2009. Mussels growing on the riverbed were found to be more contaminated than oysters growing in the water column. A step change in the levels of the microbial indicator was identified in both species from all harvesting areas. The highest levels of E. coli were detected when total rainfall exceeded 2 mm and water levels in the main tributaries exceeded the mean flow. The magnitude of response in levels of E. coli to these hydrological events varied between species and monitoring points, but was consistently higher between the 3rd and 4th days after the rainfall event. This lag time is assumed to result from catchment topography and geology determining peak levels of runoff at the headwaters 12-24 h after rainfall events. It is considered that future risk management measures may include sampling targeting hydrograph events.

Results of field investigations into the impact of intermittent sewage discharges on the microbiological quality of wild mussels (Mytilus edulis) in a tidal estuary.

Field surveys were designed to examine the effects of sewage contamination from storm overflow effluent on faecal coliform and Escherichia coli concentrations in the flesh of wild mussels (Mytilus edulis). Bags containing 30 mussels each were fixed at known inter-tidal locations and retrieved at intervals following discharge from a nearby combined sewer overflow (CSO). Concentrations of faecal coliform bacteria and E. coli were measured in the shellfish flesh and in samples of overlying water prior to collection of the mussel samples. Faecal coliform and E. coli concentrations in shellfish increased rapidly after CSO discharge. E. coli concentrations exceeded the European shellfish hygiene class C limit of 46,000 100g(-1), and decayed during subsequent CSO discharge-free periods. The concentration and depuration response was independent of the magnitude of CSO spill volume. First-order exponential decay functions were fitted to the data. Decay rates were lower than those found in corresponding microcosm experiments. This relates to the repeated pattern of inundation and exposure associated with the tidal cycles in the estuary. Relationships between E. coli and faecal coliform concentrations in the shellfish and overlying water samples were relatively weak (r<0.60), a pattern often seen with data from uncontrolled environmental experiments.

The nuclear BAG-1 isoform, BAG-1L, enhances oestrogen-dependent transcription.

BAG-1 is a multifunctional protein that interacts with a wide range of cellular targets including heat-shock proteins and some nuclear hormone receptors. BAG-1 exists as three major isoforms, BAG-1L, BAG-1M and BAG-1S. BAG-1L contains a nuclear localization signal, which is not present in the other isoforms, and is predominantly localized in the cell nucleus. Here we have investigated the effects of BAG-1 on function of the oestrogen receptor (ER), a key growth control molecule and target for hormonal therapy in breast cancer. We demonstrate that BAG-1L, but not BAG-1S or BAG-1M, increased oestrogen-dependent transcription in breast cancer cells. BAG-1L interacted with and stimulated the activity of both ER alpha and beta. Although BAG-1L and ERs colocalize to the nucleus, fusing BAG-1S to an heterologous nuclear localization sequence was not sufficient to stimulate transcription. Consistent with an important effect on receptor function, nuclear BAG-1 expression in breast cancers was associated with expression of the progesterone receptor, a transcriptional target of ERalpha, and was associated with improved survival in patients treated with hormonal therapy. These data suggest that BAG-1L is an important determinant of ER function in vitro and in human breast cancer.