Biomedical subjects

Rebecca Klaper

Publications and source records attributed to Rebecca Klaper.

3 recordsLinked to original sources

PubMed2006

Gene expression changes related to endocrine function and decline in reproduction in fathead minnow (Pimephales promelas) after dietary methylmercury exposure.

BACKGROUND: Methylmercury (MeHg) is a known neurotoxic agent, but the mechanisms by which MeHg may act on reproductive pathways are relatively unknown. Several studies have indicated potential changes in hormone levels as well as declines in vertebrates with increasing dietary MeHg exposure. OBJECTIVES: The purpose of this study was to identify alterations in gene expression associated with MeHg exposure, specifically those associated with previously observed changes in reproduction and reproductive biomarkers. Fathead minnows, Pimephales promelas, were fed one of three diets that were similar to documented concentrations of MeHg in the diets of wild invertivorous and piscivorous fish. We used a commercial macroarray in conjunction with quantitative polymerase chain reaction to examine gene expression in fish in relation to exposure to these environmentally relevant doses of MeHg. RESULTS: Expression of genes commonly associated with endocrine disruption was altered with Hg exposure. Specifically, we observed a marked up-regulation in vitellogenin mRNA in individual Hg-exposed males and a significant decline in vitellogenin gene expression in female fish with increasing Hg concentrations. Other genes identified by the macroarray experiment included those associated with egg fertilization and development, sugar metabolism, apoptosis, and electron transport. We also observed differences in expression patterns between male and female fish not related to genes specifically associated with reproduction, indicating a potential physiological difference in the reaction of males and females to MeHg. CONCLUSION: Gene expression data may provide insight into the mechanisms by which MeHg affects reproduction in fish and indicate how MeHg differs in its effect from other heavy metals and endocrine-disrupting compounds.

Animal Feed↗

PubMed2006

Daphnia magna mortality when exposed to titanium dioxide and fullerene (C60) nanoparticles.

Nanoparticles (1-100 nm) comprise the latest technological advances designed to do everything from absorb environmental toxins to deliver drugs to a target organ. Recently, however, they have come under scrutiny for the potential to cause environmental damage. Because compounds in this miniature size range have chemical properties that differ from those of their larger counterparts, nanoparticles deserve special attention. Our main objective was to assess the potential impact that nanoparticles may have on release into aquatic environments. We prepared titanium dioxide (TiO2) and fullerene (C60) nanoparticles by filtration in tetrahydrofuran or by sonication. Daphnia magna were exposed to the four solutions using U.S. Environmental Protection Agency 48-h acute toxicity tests. Images of the particle solutions were recorded using transmission-electron microscopy, and the median lethal concentration, lowest-observable-effect concentration, and no-observable-effect concentration were determined. Exposure to filtered C60 and filtered TiO2 caused an increase in mortality with an increase in concentration, whereas fullerenes show higher levels of toxicity at lower concentrations. Exposure to the sonicated solutions caused varied mortality. Understanding the potential impacts of nanoparticles will help to identify the most appropriate nanotechnology to preserve the aquatic environment while advancing medical and environmental technology.

Animals↗

PubMed2004

Genomics for the ecological toolbox.

Genomics technologies have expanded the types of question that can be addressed in human genetics and health and in fields such as ecology. Genome-scale approaches provide ways to examine physiological changes that occur when a pathogen invades a host, the response of an organism to a change in its environment, and the way in which changes in the microbial community affect ecosystem function. Here, we examine successful applications of genomics to ecological science to date and describe ways that classic ecological research disciplines might benefit from genomic approaches. We also address some of the challenges of using this methodology, and discuss how ecological researchers embracing these approaches enhance its effectiveness in applications such as gene hunting and gene expression analysis.

Journal Article↗