Analysis of the toxicogenomic effects of exposure to persistent organic pollutants (POPs) in Slovakian girls: correlations between gene expression and disease risk

The chemical composition of persistent organic pollutants (POPs) in the environment is not uniform throughout the world, and these contaminants contain many structurally different lipophilic compounds. In a well-defined study cohort in the Slovak Republic, the POP chemicals present in the peripheral blood of exposed children were chemically analyzed. The chemical analysis data revealed that the relative concentration and profile of structurally different organic pollutants, including polychlorinated biphenyls (PCBs), 2,2′-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p′-DDE), 2,2′-bis(4-chlorophenyl)-1,1,1-trichloro-ethane (p,p′-DDT), hexachlorobenzene (HCB) and β-hexachlorocyclohexane (β-HCH), may vary from individual to individual, even within the same exposure area. These chemicals can be broadly classified into two groups. The first group, the PCB congeners, primarily originated from industrial compounds and their byproducts. The second group of compounds originated from or was commonly used in the agricultural sector (e.g., DDT, HCB). The objective of this study was to examine the effects of the two POP exposure profiles on gene expression. For the study population, we selected pre-pubertal girls (mean age of 46.2 ± 1.4 months) with high POP concentrations in their blood (> 75% tile of total POP) and classified them in the high ‘PCB’ group when the total PCB concentration was significantly higher than the total concentration of other POP components and in the ‘Other Than PCB’ (OTP) group, when the total PCB concentration was significantly lower than the concentration of the other major POP constituents. A matched control group of girls (< 25% tile of total POP) was selected for comparison purpose (n = 5 per group). Our aims were to determine whether there were any common effects of high POP exposure at a toxicogenomic level and to investigate how exposure may affect physiological functions of the children in two different exposure scenarios. Global gene expression analysis using a microarray (Affymetrix Gene Chip Human genome U133 Plus 2.0 Array) platform was conducted on the total RNA of peripheral blood mononuclear cells from the girls. The results were analyzed by Partek GS, Louis, MI, which identified twelve genes (ATAD2B, BIVM, CD96, CXorf39, CYTH1 ETNK1, FAM13A, HIRA, INO80B, ODG1, RAD23B, and TSGA14) and two unidentified probe sets, as regulated differentially in both the PCB and OTP groups against the control group. The qRT-PCR method was used to validate the microarray results. The Ingenuity Pathway Analysis (IPA) software package identified the possible molecular impairments and disease risks associated with each gene set. Connective tissue disorders, genetic disorders, skeletal muscular disorders and neurological diseases were associated with the 12 common genes. The data therefore identified the potential molecular effects of POP exposure on a genomic level. This report underscores the importance of further study to validate the results in a random population and to evaluate the use of the identified genes as biomarkers for POP exposure.     

Measurement and modelling of radioxenon plumes in the Ottawa Valley

Since 2001 a real-time radiation monitoring network of Canadian nuclear facilities and major population centres has been implemented for response to nuclear incidents including a possible terrorist attack. Unshielded NaI(Tl) spectroscopic detectors are employed to measure gamma radiation from airborne radioactivity and radioactivity deposited on the ground. These detectors are composed of a standard 3'x3' cylindrical NaI(Tl) spectrometers with data storage and integrated telemetry. Some of the detectors have been deployed in the Ottawa Valley near Chalk River Laboratories and Ottawa, which has a complex radioxenon environment due to the proximity of nuclear power reactors, and medical isotope facilities. Although not a health threat, these releases have provided an opportunity for the Canadian Meteorological Centre and the Commissariat à l'Energie Atomique to validate their meteorological models. The meteorological models of the two organizations are in good agreement on the origin and the source terms of these releases.     

Effects of lead-contaminated sediment and nutrition on mallard duckling brain growth and biochemistry

Day-old mallard (Anas platyryhnchos) ducklings received either a clean sediment (24%) supplemented control diet, Coeur d'Alene River Basin, Idaho (CDARB) sediment (3449 microg/g lead) supplemented diets at 12% or 24%, or a positive control diet (24% clean sediment with equivalent lead acetate to the 24% CDARB diet) for 6 weeks. The 12% CDARB diet resulted in a geometric mean concentration of 396 ppb (WW) brain lead with decreased brain protein and ATP concentrations but increased oxidized glutathione (GSSG) relative to the control diet. The 24% CDARB diet resulted in a concentration of 485 ppb brain lead with lower brain weight and ATP concentration than controls but higher concentrations of reduced glutathione (GSH) and calcium. Lead acetate accumulated twice as well as CDARB derived lead and resulted in histopathological lesions of the brain. With a combination of a suboptimal diet and 24% CDARB, brain lead concentration was higher (594 ppb) than with 24% CDARB in the standard diet, histopathological lesions became apparent and GSH was higher than suboptimal diet controls.     

Effects of brooding and broadcasting reproductive modes on the population genetic structure of two Antarctic gastropod molluscs

Life-history characteristics exert a profound influence upon the population structure of many marine organisms. However, relatively few genetic studies have compared direct with indirect-developing species in the same ecosystem or geographical region, and none to our knowledge within an Antarctic setting. To address this issue, we have collected novel amplified fragment length polymorphism (AFLP) data from the direct-developing top shell Margarella antarctica to form a comparison with previously published data for the broadcast-spawning Antarctic limpet Nacella concinna. We scored 270 loci in 240 M. antarctica individuals sampled from five populations spanning the full length of the Antarctic Peninsula. Profound differences were identified in the strength and pattern of population structure between the two species, consistent with gene flow being highly restricted in M. antarctica relative to N. concinna.     

Quantitative tools for implementing the new definition of significant portion of the range in the U.S. Endangered Species Act

In 2014, the Fish and Wildlife Service (FWS) and National Marine Fisheries Service announced a new policy interpretation for the U.S. Endangered Species Act (ESA). According to the act, a species must be listed as threatened or endangered if it is determined to be threatened or endangered in a significant portion of its range (SPR). The 2014 policy seeks to provide consistency by establishing that a portion of the range should be considered significant if the associated individuals’ “removal would cause the entire species to become endangered or threatened.” We reviewed 20 quantitative techniques used to assess whether a portion of a species’ range is significant according to the new guidance. Our assessments are based on the 3R criteria—redundancy (i.e., buffering from catastrophe), resiliency (i.e., ability to withstand stochasticity), and representation (i.e., ability to evolve)—that the FWS uses to determine if a species merits listing. We identified data needs for each quantitative technique and considered which methods could be implemented given the data limitations typical of rare species. We also identified proxies for the 3Rs that may be used with limited data. To assess potential data availability, we evaluated 7 example species by accessing data in their species status assessments, which document all the information used during a listing decision. In all species, an SPR could be evaluated with at least one metric for each of the 3Rs robustly or with substantial assumptions. Resiliency assessments appeared most constrained by limited data, and many species lacked information on connectivity between subpopulations, genetic variation, and spatial variability in vital rates. These data gaps will likely make SPR assessments for species with complex life histories or that cross national boundaries difficult. Although we reviewed techniques for the ESA, other countries require identification of significant areas and could benefit from this research.     

Arsenic uptake and loss in the American oyster,Crassostrea virginica

In addition to a control Crassostrea virginica was treated with 3 and 5 g As kg^p-1 for 16 wks at ambient seawater salinity and temperature to determine the potential of C. virginica as an indicator of arsenic pollution. Prior to spawning, as much as 10.3±1.5, 12.7±2.7, and 14.1±3.7 g As g^p-1 dry weight were accumulated in the total soft parts of oysters after treatment with ambient (control), 3 and 5 g As kg^-1, respectively. Immediately after spawning, an increase in tissue arsenic concentration was observed in all treatments up to week 12, after which a decrease in tissue arsenic concentrations occurred despite continuous addition of arsenic to the seawater. During the uptake period, a significant inverse relationship existed between dry weight and tissue arsenic concentration, whereas a significant direct relationship was apparent between dry weight and tissue content. Arsenic concentration in the total soft parts is not significantly related to seawater arsenic concentration over the range of concentrations used in this study. In all three treatments, arsenic uptake as concentration (g g^p-1) is not a significant linear function of time. Weight loss was significant but gradual during the first 16 wks of treatment and did not change significantly during the depuration period (wks 17–25). Tissue arsenic concentrations increased significantly in oysters from all three treatments during the depuration period. Generally, arsenic body burdens increased with increases in phytoplankton concentration and it appears that food contributes more to arsenic uptake than seawater arsenic concentrations. Since a relationship between tissue arsenic concentration and seawater arsenic concentration does not appear to exist, C. virginica would not be a good biological indicator of arsenic concentration in its environment.