Suppression of aromatase activity in populations of bream (Abramis brama) from the river Elbe, Germany

Aromatase activity was determined in brain and gonads of wild bream collected along the river Elbe, Germany, and correlated with other endocrine and reproductive endpoints such as plasma sex steroid concentrations, secondary sex characteristics (STI), plasma vitellogenin, gonad size (GSI), and maturation stages of germ cells (MS) that were reported for the same fish in a previous study. Furthermore, regional patterns of aromatase activity were correlated to a number of environmental factors such as exposure to environmental contaminants and parasitism. While aromatase activity was not detectable in the gonads of male and female fish with the assay used, fish of both genders revealed relatively great brain enzyme activities. As for most of the endocrine and reproductive parameters, with the exception of plasma testosterone (T), aromatase activities were significantly less in fish from a river stretch characterized by elevated exposures to organic contaminants and metals. Brain aromatase activity was positively and significantly correlated with plasma estradiol (E2) and MS in females, and showed a similar trend with plasma 11-ketotestosterone (11KT) and STI in males. No comparable trend occurred for T. This decrease of the reproductively relevant hormones 11KT and E2 may be indicative of a disruption of the last step in sex hormone synthesis, a hypothesis that was supported for E2 by the strong (R2=0.78, p<0.05) linear regression between aromatase activity and E2 in female bream. It is also hypothesized that the effects on brain aromatase activity were likely to be related to the disruption of other reproductive parameters including sexual maturity and expression of secondary sex characteristics. Although a number of factors such as exposure to pollutants and prevalence of the tapeworm Ligula intestinalis correlated with the suppression of aromatase activity, the exact causes for the regional decrease in brain aromatase activity remain unclear due to inconsistencies of these correlations between sampling events or gender.     

Banana Production Systems: Identification of Alternative Systems for More Sustainable Production

Large-scale, monoculture production systems dependent on synthetic fertilizers and pesticides, increase yields, but are costly and have deleterious impacts on human health and the environment. This research investigates variations in banana production practices in Costa Rica, to identify alternative systems that combine high productivity and profitability, with reduced reliance on agrochemicals. Farm workers were observed during daily production activities; 39 banana producers and 8 extension workers/researchers were interviewed; and a review of field experiments conducted by the National Banana Corporation between 1997 and 2002 was made. Correspondence analysis showed that there is no structured variation in large-scale banana producers’ practices, but two other banana production systems were identified: a small-scale organic system and a small-scale conventional coffee–banana intercropped system. Field-scale research may reveal ways that these practices can be scaled up to achieve a productive and profitable system producing high-quality export bananas with fewer or no pesticides.     

Aquatic microcosm assessment of the effects of tylosin on Lemna gibba and Myriophyllum spicatum

Tylosin is a macrolide antibiotic commonly used for therapeutic treatment and prophylaxis in livestock. As part of a larger ecotoxicological study, the potential phytotoxic effects of tylosin on the rooted macrophyte Myriophyllum spicatum and the floating macrophyte Lemna gibba were assessed under semi-field conditions using 15 12 000-L microcosms. Concentrations of 0, 10, 30, 300 microg/L (n = 3), and 600, 1000, and 3000 microg/L (n = 1) were evaluated as part of separate ANOVA and regression analyses over an exposure period of 35 days. Fate of tylosin was monitored over time in the highest three treatments, where dissipation followed pseudo-first order kinetics with associated half-lives ranging from 9 to 10 days. For both M. spicatum and L. gibba, tylosin was found to cause no biologically significant changes to any endpoint assessed compared to controls at a Type I error rate of 0.1. However, subsequent power analyses revealed that there was generally insufficient power to declare that there were no significant differences at a Type II error rate of 0.2. Conclusions concerning biologically significant impacts were therefore further assessed based on other statistical criteria including comparisons of percent differences between replicated treatments and controls, minimum significant and minimum detectable differences, and coefficients of variation. Based on these criteria, at an ecological effect size of >20% change, tylosin was concluded to elicit no biologically or ecologically significant toxicity to M. spicatum or L. gibba. A hazard quotient assessment indicated that tylosin poses little risk to either species of macrophyte, with an HQ value calculated to be nearly three orders of magnitude below 1 (0.002).     

Nutrient movement and removal in a switchgrass biomass-filter strip system treated with dairy manure

Manure use on cropland has raised concern about nutrient contamination of surface and ground waters. Warm-season perennial grasses may be useful in filter strips to trap manure nutrients and as biomass feedstock for nutrient removal. We explored the use of 'Alamo' switchgrass (Panicum virgatum L.) in a biomass production-filter strip system treated with dairy manure. We measured changes in extractable P in the soil, NO3 -N in soil water, and changes in total reactive P and chemical oxygen demand (COD) of runoff water before and after a switchgrass filter strip. Five rates of dairy manure (target rates of 0, 50, 100, 150, and 200 kg N ha(-1) from solid manure in 1995; 0, 75, 150, 300, and 600 kg N ha(-1) from lagoon effluent in 1996 and 1997) were surface-applied to field plots of switchgrass (5.2 by 16.4 m) with a 5.2- by 16.4-m switchgrass filter strip below the manured area. Yield of switchgrass from the manured area increased linearly with increasing manure rate in each year. Soil water samples collected at 46 or 91 cm below the soil surface on 30 dates indicated < 3 mg L(-1) of NO3-N in all plots. Concentrations of total reactive P in surface runoff water were reduced an average of 47% for the 150 kg N rate and 76% for the 600 kg N rate in 1996 and 1997 after passing through the strip. Manure could effectively substitute for inorganic fertilizer in switchgrass biomass production with dual use of the switchgrass as a vegetative filter strip.     

Spectral deconvolution and operational use of stripping ratios in airborne radiometrics

Spectral deconvolution using stripping ratios for a set of pre-defined energy windows is the simplest means of reducing the most important part of gamma-ray spectral information. In this way, the effective interferences between the measured peaks are removed, leading, through a calibration, to clear estimates of radionuclide inventory. While laboratory measurements of stripping ratios are relatively easy to acquire, with detectors placed above small-scale calibration pads of known radionuclide concentrations, the extrapolation to measurements at altitudes where airborne survey detectors are used bring difficulties such as air-path attenuation and greater uncertainties in knowing ground level inventories. Stripping ratios are altitude dependent, and laboratory measurements using various absorbers to simulate the air-path have been used with some success. Full-scale measurements from an aircraft require a suitable location where radionuclide concentrations vary little over the field of view of the detector (which may be hundreds of metres). Monte Carlo simulations offer the potential of full-scale reproduction of gamma-ray transport and detection mechanisms. Investigations have been made to evaluate stripping ratios using experimental and Monte Carlo methods.     

Injury risk in behind armor blunt thoracic trauma.

First responders and military personnel are particularly susceptible to behind armor blunt thoracic trauma in occupational scenarios. The objective of this study was to develop an armored thorax injury risk criterion for short duration ballistic impacts. 9 cadavers and 2 anthropomorphic test dummies (AUSMAN and NIJ 0101.04 surrogate) were tested over a range of velocities encompassing low severity impacts, medium severity impacts, and high severity impacts based upon risk of sternal fracture. Thoracic injuries ranged from minor skin abrasions (abbreviated injury scale [AIS] 1) to severe sternal fractures (AIS 3+) and were well correlated with impact velocity and bone mineral density. 8 male cadavers were used in the injury risk criterion development. A 50% risk of AIS 3+ injury corresponded to a peak impact force of 24,900 +/- 1,400 N. The AUSMAN impact force correlated strongly with impact velocity. Recommendations to improve the biofidelity of the AUSMAN include implementing more realistic viscera and decreasing the skin thickness.     

Investigation of long-term hazards of chemical weapon agents in the environment of Sardasht area,Iran

Environmental Science and Pollution Research - The present study aimed to investigate the persistence and existence of chemical warfare agents (CWAs) and related dissipation products in the...