The second focus of our lab deals with both natural and anthropogenic stressors. We have been investigating the mechanisms by which phylogenetic differences in contaminant tolerance occur in embryos exposed to hydrophobic chemicals; these include polycyclic aromatic hydrocarbons, pharmaceuticals, and agrochemicals. This research includes the study of the multidrug resistance transporter family (ABC transporters) of proteins and their expression in embryos/larvae as well as adult tissues (Nature McGinn, Ph.D. candidate).
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Image, right: Gonads of Longjaw mudsucker collected from SF Bay salt marsh. This fish shows evidence of endocrine disruption with the condition known as “ovotestes”. The upper gonad is an enlarged testes with sperm, while the smaller lower gonad consists of some testicular tissue and ovary, orange color. (Carol Vines and Susanne Brander) |
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Control zebrafish embryos labeled with antibody to Beta-catenin (green). The cell membrane boundaries are visible with some cytoplasmic labeling. Few nuclei label. Blue labeling on right are labeled with a nuclear stain. |
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Zebrafish embryos exposed to polycyclic aromatic hydrocarbons show Beta-catenin (green) accumulating in nuclei. Blue labeling on right shows nuclei locations of same embryo. |
This research also focuses on the effects of environmental chemicals on embryonic axis determination in echinoderms and teleost fish embryos (Ellie Fairbairn, Ph.D. candidate; Dr. Carol Vines). The Beta-catenin signaling pathway is the focus of this work. In another project, we are investigating reproductive impairment in California marsh fish, including endocrine disruption and the expression of egg chorion proteins in males exposed to estrogenic compounds. This is part of a larger program that was recently completed to develop new indicators of condition of salt marsh organisms as part of a US EPA-supported program, PEEIR.
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Sea urchin embryos MXR or ABC transporter work by Nature McGinn
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Movie of sperm loaded with the calcium probe Fluo-4 show cytoplasmic fluorescence as they swim. Imaging accomplished with the laboratory’s scanning laser confocal microscope. The left side is fluorescence and the right is the overlay of fluorescence over interference contrast. VIEW
Movie of Fluo-4 loaded sperm entering the egg’s micropylar canal. As sperm enter, flashes of calcium increases can be seen. The left side is fluorescence and the right is the overlay of fluorescence over interference contrast. VIEW |
Note that YOU MUST have QUICKTIME to view these movies.
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Gary Cherr, Ph.D.