A fish hepatocyte model for the investigation of the effects of environmental contaminants

An isolated fish hepatocyte culture system was developed as a models ystem to investigate the mechanisms of action of environmental contaminants. Hepatocytes were isolated from striped bass (Morone saxatilis) by an adaptation of the two stage perfusion technique of Seglen.¹ The system was used to evaluate metal binding protein (MBP) induction in response to cadmium, a primary inducer of metallothionein (MT) in rat hepatocytes. Striped bass hepatocytes appeared to be refractory to the induction of MBP by cadmium, since there was no significant increase in the synthesis of MBP for any of the doses at any of the time points investigated. However, when a similar experiment was performed using rat hepatocytes there was induction of MBP that was related to both dose and time. These comparative experiments indicate that although there are similarities between the hepatocytes of the two species in regard to ³⁵S incorporation into low molecular weight metal-binding proteins, there appear to be significant quantitative differences as well in regard to MBP kinetics. This in vitro model system could potentially be utilized to investigate the toxicological properties of other environmental contaminants.     

Oxidative stress in two populations of killifish (Fundulus heteroclitus) with differing contaminant exposure histories

A population of killifish (Fundulus heteroclitus) inhabiting a creosote-polluted inlet of the Elizabeth River demonstrates tolerance to the acute toxic effects exerted by contaminated sediments on reference site killifish. Previous data have suggested that upregulated antioxidant defenses contribute to short-term tolerance in killifish exposed to Elizabeth River sediments. This study investigated population differences in antioxidant defenses from wild caught Elizabeth River and reference population killifish in different seasons, and after being held in the laboratory. Parameters measured in the killifish were total glutathione concentrations (GSH(T)), activities of glutathione reductase (GR), glutathione peroxidase (GPx), and lipid peroxidation (LPO), all in adult hepatic tissues. The Elizabeth River population exhibited greater GSH(T), higher GPx activities, and increased LPO as compared to the reference population. Sex specific population differences were also observed in GSH(T) and GPx. Both populations displayed decreased GSH(T) and increased GR from early to late summer, as well as after being held in the laboratory. This study indicates that there are many factors that may contribute to differences in levels of antioxidant defenses in addition to exposure to contaminants, including reproductive status and environmental conditions.     

Composition and distribution of meiobenthos in amursky bay (peter the great bay, the east sea)

Qualitative and quantitative composition of meiobenthos was studied in Amursky Bay (Peter the Great Bay, the East Sea). Ten taxonomic groups were found, where nematodes were dominant. Density of meiobenthos in ground sediments of the Bay were not uniform, and the average density was measured at 126.4±62.3 ind. m^-2. 56 species of nematodes were detected, and dominant species wereSabatieria palmaris, Paracanthonchus macrodon, Sphaerolaimus limosus, S. gracilis andOncholaimium ramosum. Five taxocenes of nematodes were allocated based on the results of cluster analysis and species domination according to density. Low diversity in species composition of nematodes was noted in the northwestern part of the Bay, which is a zone of desalination, and in the eastern part, which is exposed to household drains.     

Estrogenic responses of larval sunshine bass (Morone saxatilis x M. Chrysops) exposed to New York City sewage effluent

To determine the estrogenicity of effluents from sewage treatment plants (STPs) to larval fish, 2-day-old sunshine bass were exposed to effluents from three STPs serving New York City (NYC), varying in size and treatment level. Estrogenic response was evaluated by measuring vitellogenin (VTG) and estrogen receptor (ER) expression in cytosolic fractions of whole body homogenates. Concentrations of the presumptive endocrine disruptors in the effluents were also measured. VTG and ER levels in sewage-exposed fish were 3-5 times that observed in controls. Combined concentrations of estradiol and estrone ranged from 5 to 13 ng/l and nonylphenol-ethoxylate metabolites (NPEOs: 4-nonylphenol, and 1-, 2-, and 3-nonylphenol-ethoxylates) ranged from 180 to 470 microg/l in chlorinated effluent. Results indicate that both ER and VTG can be used as biomarkers for endocrine disruption in larval fish, and that 4-day exposure to sewage effluent is sufficient to elicit significant expression of these markers in sunshine bass larvae. The extremely higher concentrations of NPEOs found in effluent relative to hormones (approximately 40,000-fold) indicates that surfactant metabolites may be contributing significantly to the estrogenic effects observed.     

MAROS: a decision support system for optimizing monitoring plans

The Monitoring and Remediation Optimization System (MAROS), a decision-support software, was developed to assist in formulating cost-effective ground water long-term monitoring plans. MAROS optimizes an existing ground water monitoring program using both temporal and spatial data analyses to determine the general monitoring system category and the locations and frequency of sampling for future compliance monitoring at the site. The objective of the MAROS optimization is to minimize monitoring locations in the sampling network and reduce sampling frequency without significant loss of information, ensuring adequate future characterization of the contaminant plume. The interpretive trend analysis approach recommends the general monitoring system category for a site based on plume stability and site-specific hydrogeologic information. Plume stability is characterized using primary lines of evidence (i.e., Mann-Kendall analysis and linear regression analysis) based on concentration trends, and secondary lines of evidence based on modeling results and empirical data. The sampling optimization approach, consisting of a two-dimensional spatial sampling reduction method (Delaunay method) and a temporal sampling analysis method (Modified CES method), provides detailed sampling location and frequency results. The Delaunay method is designed to identify and eliminate redundant sampling locations without causing significant information loss in characterizing the plume. The Modified CES method determines the optimal sampling frequency for a sampling location based on the direction, magnitude, and uncertainty in its concentration trend. MAROS addresses a variety of ground water contaminants (fuels, solvents, and metals), allows import of various data formats, and is designed for continual modification of long-term monitoring plans as the plume or site conditions change over time.     

Distribution, abundance and life history of Mysis relicta (Lovén) in the Feldberg Lake District, Germany

Distribution, abundance and life history characteristics of Mysis relicta were studied in the Feldberg Lake District (Lake Breiter Luzin, Lake Schmaler Luzin, Lake Zansen) located in northeastern Germany. Between July 2001 and November 2002 mysids were collected by vertical net hauls. In order to determine the impact of the current trophic conditions on the distribution of mysids in these lakes, oxygen concentration, total phosphorus, chlorophyll a and water transparency were also measured. All investigated lakes are mesotrophic at present. Lake Breiter Luzin exhibited great seasonal and spatial variations in mysid abundance. Density of adults and juveniles had a mean of 44.9 ± 57.1 and 68.7 ± 99.6 m⁻², respectively. Highest abundance of adults was 110.4 ± 76.5 m⁻² in summer, lowest abundances of 2.0 ± 4.0 m⁻² occurred in spring. For juveniles, highest density of 218.4 ± 174.6 m⁻² was detected in summer and lowest of 0.8 ± 1.8 m⁻² in winter. No mysids were caught in any of the daytime hauls, but they were widely distributed throughout the water column at night. Size frequency distribution of mysids suggested that reproduction occurred year-round, the most consistent influx of juveniles occurred in early summer and a smaller second cohort in autumn. Highest mysid abundance was 189.2 ± 318.6 adults and 127.0 ± 66.3 juveniles m⁻² in Lake Schmaler Luzin, and 59.6 ± 5.6 adults and 79.4 ± 11.2 juveniles m⁻² in Lake Zansen. There were great spatial differences in abundance in both lakes.     

Contaminants in sediments from the central Gulf of Mexico

Surface sediment samples at 89 locations and 300-cm cores from 43 sites in the Mississippi Sound were examined for evidence of pollutant impact upon this coastal environment. Chemical variables determined were total organic carbon, Kjeldahl nitrogen, phenols, and hydrocarbons. Values of these pollutant indicators were about the same or lower in Gulf of Mexico samples compared to Missippi Sound sediments and considerably lower than those from rivers and bays emptying into the sound, indicating limited impact from sites of pollutant sources into the sound. Concentrations of sedimentary pollutants peaked in the Pascagoula River where levels of total organic carbon (TOC), Kjeldahl nitrogen (TKN), phenols, and hydrocarbons exceeded sound values by one to three orders of magnitude. Analysis of cores shows pollutant intrusion to sediment strata predating industrial development. The level of pollution varies from site to site but fortunately is only serious at localized sites within the sound.     

The color of the Kuiper belt Core

Recent dynamical analyses of the Kuiper belt have introduced a rigorous classification scheme, determined the mean orbital plane, and identified “Core” and “Halo” populations as a function of inclination with respect to this plane (Elliot, J.L., Kern, S.D., Clancy, K.B., Gulbis, A.A.S., Millis, R.L., Buie, M.W., Wasserman, L.H., Chiang, E.I., Jordan, A.B., Trilling, D.E., Meech, K.J., 2005. Astron. J. 129, 1117-1162). Here, we use new observations and existing data to investigate the colors of Kuiper belt objects (KBOs) within this framework. With respect to the bulk KBO color distribution (all objects for which we have B-V and V-R colors; median B-R=1.56), we find that the population of objects classified following (Elliot, J.L., Kern, S.D., Clancy, K.B., Gulbis, A.A.S., Millis, R.L., Buie, M.W., Wasserman, L.H., Chiang, E.I., Jordan, A.B., Trilling, D.E., Meech, K.J., 2005. Astron. J. 129, 1117-1162) as Classical tends to be red (B-R>1.56) while the Scattered Near population is mostly neutral (B-R<1.56). Colors of Scattered Extended and Resonant objects are consistent with the bulk distribution. Separating objects into specific resonances demonstrates that the color of the Resonant sample is dominated by KBOs in the 3:2 resonance, which is consistent with previous findings. Unlike the objects in the 3:2 resonance, however, the majority of objects in the 5:2 resonance are neutral and all but one of the objects in the 4:3, 5:3, 7:4, 2:1, and 7:3 resonances are red. In particular, the objects in the 7:4 resonance are remarkably red. We find that the colors of KBOs in the Core (low-inclination) and Halo (high-inclination) are statistically different, with Core objects being primarily red and Halo objects having a slight tendency to be neutral. Notably, virtually all of the non-Resonant Core objects are red. This combination of low inclination, unperturbed orbits and red colors in the Core may be indicative of a relic grouping of objects.