Effects of ammonium perchlorate on the reproductive performance and thyroid follicle histology of zebrafish.
Adult zebrafish were reared up to eight weeks in control water or in water containing ammonium perchlorate (AP) at measured perchlorate concentrations of 18 (environmentally relevant, high) and 677 ppm. Groups of eight females were paired with four males on a weekly basis to assess AP effects on spawned egg volume, an index of reproductive performance. All treatments were applied to four to five spawning replicates. At 677 ppm, spawn volume was reduced within one week and became negligible after four weeks. At 18 ppm, spawn volume was unaffected even after eight weeks. Also, perchlorate at 18 ppm did not affect percentage egg fertilization. Fish were collected at the end of the exposures (677 ppm, four weeks; control and 18 ppm, eight weeks) for whole-body perchlorate content and thyroid histopathological analysis. Fish perchlorate levels were about one-hundredth of those of treatment water levels, indicating that waterborne perchlorate does not accumulate in whole fish. At 677 ppm for four weeks, perchlorate caused thyroid follicle cell (nuclear) hypertrophy and angiogenesis, whereas at 18 ppm for eight weeks, its effects were more pronounced and included hypertrophy, angiogenesis, hyperplasia, and colloid depletion. In conclusion, an eight-week exposure of adult zebrafish to 18 ppm perchlorate (high environmentally relevant concentrations) affected the histological condition of their thyroid follicles but not their reproductive performance. The effect of 677 ppm perchlorate on reproduction may be due to extrathyroidal toxicity. Further research is needed to determine if AP at lower environmentally relevant concentrations also affects the thyroid follicles of zebrafish.
Patiño
Reynaldo
R
U.S. Geological Survey, and Texas Cooperative Fish and Wildlife Research Unit, Texas Tech University, Lubbock, Texas 79409, USA. reynaldopatino@ttu.edu
Wainscott
Melody R
MR
Cruz-Li
Emilia I
EI
Balakrishnan
Saravanan
S
McMurry
Cynthia
C
Blazer
Vicki S
VS
Anderson
Todd A
TA
D000818:Animals; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D005306:Fertilization / Q000187:drug effects; D008297:Male; D010063:Ovum / Q000187:drug effects / Q000502:physiology; D010472:Perchlorates / Q000633:toxicity*; D000644:Quaternary Ammonium Compounds / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects*; D013961:Thyroid Gland / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000502:physiology*
D010472:Perchlorates; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; C053506:ammonium perchlorate