Endocrine disruption of the fungicide propiconazole in the frog Xenopus tropicalis: Effects on the aromatase activity and egg development
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Amphibian populations around the world are decreasing, and endocrine disrupting chemicals have been suggested as a part of the problem. The fungicide propiconazole is used in agriculture in many countries. It works as a fungicide by inhibiting CYP51, affecting the fungi cell membrane, but it has also been proven to inhibit aromatase, CYP19. Aromatase converts androgens to estrogen and is important for sexual differentiation in the early development and in reproduction in vertebrates. The aim of this study was to investigate the effect of propiconazole on the aromatase activity in brains from the West African clawed frog (Xenopus tropicalis), after larval and adult exposure and on aromatase activity in ovaries after adult exposure. Furthermore, effects on egg development was determined after adult exposure.
Tadpoles were exposed to propiconazole (0, 25, and 250 µg/L) from three days after hatching until metamorphosis. In a former study, female adult X. tropicalis were exposed to 0 and 250 µg/L propiconazole during 4 weeks. The result of the aromatase activity measurements showed that 250 µg/L propiconazole increased brain aromatase activity after larval exposure. Brain and ovarian aromatase activity was also increased compared to the controls after adult exposure to 250µg/L propiconazole. The increased aromatase activity could reflect a compensatory response to decreased estrogen levels. Propiconazole had a significant impact on egg development, with an increased proportion of atretic oocytes and a decreased proportion of vitellogenic oocytes compared to the controls. The effect on egg development seems to be the result of a low estrogen level. The results suggest that exposure to propiconazole 250 µg/L could have a negative impact on X. tropicalis fertility. Further studies to determine impacts of environmental exposure concentrations are needed to evaluate the risk of azoles to amphibian reproduction.
Place, publisher, year, edition, pages
2015. , 22 p.
propiconazole, Xenopus tropicalis, egg development, aromatase activity, endocrine disruption
Natural Sciences Other Biological Topics
IdentifiersURN: urn:nbn:se:uu:diva-256695OAI: oai:DiVA.org:uu-256695DiVA: diva2:826479
Master Programme in Biology
2015-06-03, Lärosal 2, Norbyvägen 14, Uppsala, 11:15 (English)
Berg, Cecilia, Ph.D., universitetslektorSäfholm, Moa, Ph.D., forskare
Viberg, Henrik, Ph.D., universitetslektor