The aim of this study was to assess sensitivity of early life stage zebrafish to
cadmium (Cd). Embryos and larva were exposed to Cd before the formation of
skeletal elements. Exposure times were selected to determine whether Cd
perturbed developmental processes that lead to skeletal deformities, and to
characterize the types of skeletal deformities that occurred. Embryo/larva were
exposed to 3μM, 10μM, 30μM, 100μM, 300μM, and 1000μM Cd at 12-36 hours
post fertilization (hpf), 36-60hpf, 60-84hpf, and 144-168hpf in one series of
experiments. This experiment was conducted at circumneutral pH. A second series
of experiments with these same Cd concentrations were also conducted at pH 6
with embryo/larva exposed at 12-36hpf, 36-60hpf, and 60-84hpf. The fish that
survived the exposures were raised for 40-60 days whereupon the surviving fish
were overdosed with MS222, and X-rayed. The later early life stage fish were
more sensitive to Cd toxicity; the chorion appeared to protect the earlier exposed
embryos (zebrafish hatch 48-72hpf). Embryo/larva were more resistant to toxicity
from dissolved Cd (pH 6) than particulate Cd (circumneutral pH); absence of
functional gills during early life stages perhaps explained resistance to dissolved
Cd. Notochord lesions (typically lethal within two weeks) occurred when embryos
were exposed 12-36hpf. There was no evidence for sensitivity of early life stage
zebrafish to Cd induced skeletal deformities that occurred within 40-60 days of Cd
exposures. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30221 |
| Date | 23 September 2003 |
| Creators | Harden, Jon M. |
| Contributors | Curtis, Lawrence R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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