Modulation of hepatic and intestinal glutathione S-transferases and other antioxidant enzymes by dietary lipids in streptozotocin diabetic rats

Antioxidant enzymes in liver and small intestine were investigated using control and streptozotocin diabetic rats fed diets with 5% olive, sunflower or fish oil for five weeks. In liver, Glutathione Peroxidase and Superoxide Dismutase decreased and in intestine Glutathione-S-transferase (GST) increased by diabetes. In isolated jejunum and ileum, this increase in GST activity was due to an increase in GST-alpha and -mu isoenzymes in jejunum and GST-alpha, mu and -pi in ileum. Since GST plays an important role in protecting tissues from oxidative damage, our results highlight the role of the intestine against free radicals in physiological or pathological situations.     

Fish population dynamics in a seasonally varying wetland

Small fishes in seasonally flooded environments such as the Everglades are capable of spreading into newly flooded areas and building up substantial biomass. Passive drift cannot account for the rapidity of observed population expansions. To test the ‘reaction-diffusion’ mechanism for spread of the fish, we estimated their diffusion coefficient and applied a reaction-diffusion model. This mechanism was also too weak to account for the spatial dynamics. Two other hypotheses were tested through modeling. The first—the ‘refuge mechanism’—hypothesizes that small remnant populations of small fishes survive the dry season in small permanent bodies of water (refugia), sites where the water level is otherwise below the surface. The second mechanism, which we call the ‘dynamic ideal free distribution mechanism’ is that consumption by the fish creates a prey density gradient and that fish taxis along this gradient can lead to rapid population expansion in space. We examined the two alternatives and concluded that although refugia may play an important role in recolonization by the fish population during reflooding, only the second, taxis in the direction of the flooding front, seems capable of matching empirical observations. This study has important implications for management of wetlands, as fish biomass is an essential support of higher trophic levels.     

Full‐scale in‐situ biobarrier demonstration for containment and treatment of MTBE

The Naval Facilities Engineering Service Center (NFESC), Arizona State University, and Equilon Enterprises LLC are partners in an innovative Environmental Security Technology Certification Program cleanup technology demonstration designed to contain dissolved MTBE groundwater plumes. This full‐scale demonstration is being performed to test the use of an oxygenated biobarrier at Naval Base Ventura County, in Port Hueneme, California. Surprisingly, few cost‐effective in‐situ remedies are known for the cleanup of MTBE‐impacted aquifers, and remediation by engineered in‐situ biodegradation was thought to be an unlikely candidate just a few years ago. This project demonstrates that MTBE‐impacted groundwater can be remediated in‐situ through engineered aerobic biodegradation under natural‐flow conditions. With respect to economics, the installation and operation costs associated with this innovative biobarrier system are at least 50 percent lower than those of a conventional pump and treat system. Furthermore, although it has been suggested that aerobic MTBE biodegradation will not occur in mixed MTBE‐BTEX dissolved plumes, this project demonstrates otherwise. The biobarrier system discussed in this article is the largest of its kind ever implemented, spanning a dissolved MTBE plume that is over 500 feet wide. This biobarrier system has achieved an in‐situ treatment efficiency of greater than 99.9 percent for dissolved MTBE and BTEX concentrations. Perhaps of greater importance is the fact that extensive performance data has been collected, which is being used to generate best‐practice design and cost information for this biobarrier technology. © 2001 John Wiley & Sons, Inc.     

Attitudes and behaviour towards waste management in the Dublin,Ireland region

The hypothesis of this research was that attitudes about the management of biodegradable municipal waste (BMW) are spatially variable, even within a city of modest (1.2 million) population. For a select number of representative electoral districts in the Dublin, Ireland region, residents were surveyed regarding attitudes towards waste management in general, and BMW management in particular. A total of 850 survey responses were collected. Door-to-door interviews produced 688 responses in the residential sector; these were supplemented by 162 responses to a web-based survey.The surveys revealed that the majority of households use local authority, rather than private, waste collection services (both are available). The majority of residents, regardless of the local authority in which they live, were satisfied with their waste management service. “Reducing the quantity of waste generated” was regarded the most important future issue for 28% of residential respondents. Statistical analyses of the survey responses showed that the local authority in which respondents resided significantly influenced most responses (including waste collection service used, waste service satisfaction and backyard composting activity). Many responses (including waste service satisfaction, waste management influences) were also significantly related to the respondents’ personal characteristics (e.g., education level, type of accommodation, age, etc.). These statistical results proved the hypothesis of the research and demonstrated that waste management initiatives designed for one area of the city (or, indeed, for uniform application to the city as a whole) could ignore the needs of other areas. The survey responses suggest that targeted intervention strategies would lead to improved diversion rates of BMW from landfill, a requirement of the Landfill Directive 1999/31/EC.     

Solid wastes integrated management in Rio de Janeiro: input-output analysis

This paper analyzes the socioeconomic aspects of solid waste management in Rio de Janeiro. An "input-output" methodology was used to examine how the secondary product resulting from recycling is re-introduced into the productive process. A comparative profile was developed from the state of recycling and the various other aspects of solid waste management, both from the perspective of its economic feasibility and from the social aspects involved. This was done analyzing the greenhouse gas emissions and the decreased energy consumption. The effects of re-introducing recycled raw materials into the matrix and the ensuing reduction of the demand for virgin raw materials was based on the input-output matrix for the State of Rio de Janeiro. This paper also analyzes the energy savings obtained from recycling and measures the avoided emissions of greenhouse gases.     

Stream buffer effectiveness in an agriculturally influenced area, southwestern Georgia: responses of water quality, macroinvertebrates, and amphibians

To determine useful metrics for assessing stream water quality in the Southeastern Coastal Plain, we examined differences among two buffered and three unbuffered streams in an agricultural landscape in southwestern Georgia. Potential indicators included amphibian diversity and abundance, aquatic macroinvertebrate populations, riparian vegetative structure, water quality, and stream physical parameters. Variability among sites and treatments (buffered vs. unbuffered) existed, with sites in the same treatment as most similar, and disturbances from a nearby eroding gully strongly affecting one unbuffered site. Of the invertebrate metrics examined, percentages of clingers, Ephemeroptera-Plecoptera-Trichoptera (EPT), Elmidae (Coleoptera), Crustacea (Decapoda and Amphipoda), and dipterans were found to be possible indicators of stream health for perennial streams within this region. Overall, buffered sites showed higher percentages of sensitive invertebrate groups and showed lower and more stable concentrations of nitrate N, suspended solids, and fecal coliforms (FCs). Percent canopy cover was similar among sites; however, riparian vegetative coverage and percent leaf litter were greatest at buffered sites. No differences in amphibian abundance, presence, and absence within the riparian area were apparent between sites; however, instream larval salamanders were more abundant at buffered streams. In this study, stream buffers appeared to decrease nutrient and sediment loads to adjacent streams, enhancing overall water quality. Selected benthic macroinvertebrate metrics and amphibian abundance also appeared sensitive to agricultural influences. Amphibians show potential as indicator candidates, however further information is needed on their responses and tolerances to disturbances from the microhabitat to landscape levels.     

Heterotrophic bacterial dynamics in the lower Fraser River,its estuary and Georgia Strait,British Columbia,Canada

Annual cycles in the glucose heterotrophic potentials of the bacterioplankton of the lower Fraser River, its estuary and Georgia Strait surface waters were observed. Maximal microbial heterotrophic potentials were noted during the winter and early spring months, whereas maximal heterotrophic productivities were observed to occur during the summer and fall months. Temperature and soluble organic carbon levels appear to be the most important of the assayed physico-chemical parameters in regulating activities and productivities of the heterotrophic microbes of these waters.     

Acute and chronic effects of clofibrate and clofibric acid on the enzymes acetylcholinesterase, lactate dehydrogenase and catalase of the mosquitofish, Gambusia holbrooki

The objective of this study was to investigate both acute and chronic effects of clofibrate and clofibric acid on the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH) and catalase (CAT) of the mosquitofish (Gambusia holbrooki). AChE, commonly used as a biomarker of neurotoxicity, was determined in the total head. LDH, an important enzyme of anaerobic metabolism, was quantified in dorsal muscle, and CAT, enzyme which has been used as indicative parameter of peroxisome proliferation, was determined in the liver. Furthermore, alterations of body and liver weight were also determined, through the calculation of the ratios final body weight/initial body weight, liver weight/final body weight, liver weight/gills weight and liver weight/head weight. Acute exposure of G. holbrooki to both clofibrate and clofibric acid induced a decrease in liver CAT activity, an increase in muscle LDH activity, while no effects were observed on AChE activity. However, chronic exposure did not alter significantly the enzymatic activities, suggesting reduced or null effects over these pathways, relative to effects reported in other species. No effects were observed for the calculated ratios, except a significant weight reduction for males chronically exposed to clofibrate.     

Trophic ecology of Rimicaris exoculata : a combined lipid abundance/stable isotope approach

The alvinocaridid shrimp Rimicaris exoculata is an abundant component of the biota of Mid-Atlantic Ridge hydrothermal vents. To determine the nutritional strategy of this organism, we analysed the molecular abundance and carbon isotopic composition of its phospholipid fatty acids. High abundances of n-7 fatty acids (>40% total fatty acids) were observed in R. exoculata muscle tissues, in bacterial epibionts scraped from its gill bailers, and from the bacterially infested metal sulphides that the shrimp ingest. The phospholipid fatty acid abundance data indicates that the bacteria in the sulphides are closely related to the bacterial epibiota inhabiting the shrimp gill bailers, carapace and other body parts. Compound specific δ¹³C analyses of the phospholipid fatty acids gave average values of −12‰ for the epibiont bacteria and −21‰ for the sulphide bacteria. This difference may be largely due to the expression of different forms of RuBisCO (Forms I and II) which fractionate against ¹³C to different extents. Carbon limitation within the shrimp epibiont population may be an additional factor. The δ¹³C values (mean = −13‰) of the saturated and monounsaturated fatty acids isolated from the muscle tissues of R. exoculata were very close to those of the epibionts, indicating that the predominant source of dietary carbon for the shrimp is their epibionts, with a lesser contribution from free-living bacteria. The δ¹³C values (−26‰) of shrimp cholesterol were much more negative than those of the fatty acids, and this cholesterol is likely to have derived from the oceanic photic zone. Received: 26 June 1997 / Accepted: 6 November 1998