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Aromatase activity in the ovary and brain of the eastern mosquitofish (Gambusia holbrooki) exposed to paper mill effluent.

By Edward F Orlando, William P Davis and Louis J Guillette


Studies have shown that female mosquitofish living downstream of a paper mill located on the Fenholloway River, Florida, have masculinized secondary sex characteristics, including altered anal fin development and reproductive behavior. Masculinization can be caused by exposure to androgens in the water or from an alteration in aromatase activity in the fish. We hypothesized that aromatase activity would be inhibited by a component(s) of the paper mill effluent. Aromatase inhibition could masculinize the hormonal profile and, subsequently, secondary sex characteristics of the exposed females. Therefore, we predicted that ovarian and brain aromatase activity would be lower in the female mosquitofish from the Fenholloway River compared with the reference site, the Econfina River. Adult females were collected and standard length, body mass, anal fin length, and segment number were measured. Ovarian and brain aromatase activity were determined using a tritiated water assay. Fenholloway females had masculinized anal fin development as indicated by an increase in the number of segments in the longest anal fin ray (p < 0.0001), yet the length of the ray did not differ between sites (p = 0.95). Fenholloway females exhibited higher ovarian (p = 0.0039) and brain (p = 0.0003) aromatase activity compared with reference site fish. These data do not support aromatase inhibition as the mechanism for masculinization, suggesting that the masculinization of the Fenholloway female mosquitofish is due to androgenic contaminants. Future studies should examine the relationship between aromatase enzyme activity and exposure to environmental androgens

Topics: Research Article
Year: 2002
OAI identifier:
Provided by: PubMed Central

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  2. (1854). A mechanism for anterior transposition of the anal fin and its appendicular support in the western mosquitofish, Gambusia affinis affinis [Baird and Girard,
  3. (1976). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.
  4. (2001). A re-examination of variation associated with environmentally stressed organisms. Hum Reprod Update
  5. (1980). Abnormal expression of secondary sex characters in a population of mosquitofish, Gambusia affinis holbrooki: evidence from environmentally-induced masculinization.
  6. (2001). Alterations in sexually dimorphic biotransformation of testosterone in American alligators (Alligator mississippiensis) from contaminated lakes.
  7. (1997). Alterations in steroidogenesis in alligators (Alligator mississippiensis) exposed naturally and experimentally to environmental contaminants.
  8. (1998). Antiandrogens as environmental endocrine disruptors. Reprod Fertil Dev
  9. (1994). Aromatase cytochrome P450, the enzyme responsible for estrogen biosynthesis. Endocr Rev
  10. (2001). Aromatase plays a key role during normal and temperature-induced sex differentiation of tilapia, Oreochromis niloticus. Mol Reprod Dev
  11. (1998). Cellular bioavailability of natural hormones and environmental contaminants as a function of serum and cytosolic binding factors.
  12. (1988). Changes in brain aromatase and 5α-reductase activities correlate significantly with seasonal reproductive cycles in goldfish (Carrasius auratus).
  13. (1992). Changes in maturity, plasma sex steroid levels, hepatic mixed-function oxygenase activity, and the presence of external lesions in lake whitefish (Coregonus clupeaformis) exposed to bleached kraft mill effluent.
  14. Contaminant interactions with steroid receptors: evidence for receptor binding. In: Environmental Endocrine Disruptors: An Evolutionary Perspective (Crain
  15. (2001). Distinct cytochrome P450 aromatase isoforms in zebrafish (Danio rerio) brain and ovary are differentially programmed and estrogen regulated during early development.
  16. (2000). Ecological and social dynamics in simple models of ecosystem management.
  17. (1998). Ecological resilience, biodiversity, scale.
  18. (2001). Effects of chloro-s-triazine herbicides and metabolites on aromatase activity in human cell lines and on vitellogenesis in male carp hepatocytes.
  19. (1999). Effects of endocrine-disrupting contaminants on amphibian oogenesis: methoxychlor inhibits progesterone-induced maturation of Xenopus laevis oocytes in vitro.
  20. (2001). Effects of environmental antiandrogens on reproductive development in experimental animals.
  21. (1992). Effects of kraft mill effluent on the sexuality of fishes: an environmental early warning? In: Chemically-Induced Alterations in Sexual and Functional Development: The Wildlife/Human Connection, vol XXI
  22. (2001). Emerging issues related to endocrine disrupting chemicals and environmental androgens and antiandrogens. In:
  23. (1998). Endocrinemodulating substances in the environment: estrogenic effects of pharmaceutical products.
  24. (2000). Environmental Endocrine Disrupters: An Evolutionary Perspective.
  25. (1997). Environmental estrogens and reproductive health: a discussion of the human and environmental data.
  26. (2001). Environmental signaling: what embryos and evolution teach us about endocrine disrupting chemicals.
  27. (1997). Environmental xenobiotics may disrupt normal endocrine function by interfering with the binding of physiological ligands to steroid receptors and binding proteins.
  28. (1999). Estrogenic potency of effluent from two sewage treatment works in the United Kingdom. Environ Toxicol Chem
  29. (1992). Exposure to bleached kraft pulp mill effluent disrupts the pituitary-gonadal axis of white sucker at multiple sites.
  30. (1995). Exposure to bleached kraft pulp mill effluent reduces the steroid biosynthetic capacity of white sucker ovarian follicles. Compar Biochem Physiol
  31. (1999). Fenholloway River Effluent Exposure Study. Results of Long-
  32. (1993). Flavanoid inhibition of aromatase enzyme activity in human preadipocytes.
  33. (1989). Gonopodial morphogenesis in female mosquitofish, Gambusia affinis, masculinized by exposure to degradation products from plant sterols.
  34. (1325). Identification of androstenedione in a river containing pulp mill effluent. Environ Toxicol Chem
  35. (1984). In vitro conversion of androgen to estrogen in amphioxus gonadal tissue.
  36. (2000). Incidence of imposex in samples of Maine's dogwhelk (Nucella lapillus) populations [Abstract]. In:
  37. (1979). Induction of vitellogenin in goldfish by massive doses of androgens.
  38. (1993). Inhibition of human aromatase by mammalian lignans and isoflavonoid phytoestrogens.
  39. (1998). Involvement of multiple biotransformation processes in the metabolic elimination of testosterone by juvenile and adult fathead minnows (Pimiphales promelas).
  40. (1999). Localization and sex steroid regulation of brain aromatase activity: identification of a positive feedback mechanism that may trigger environmental cues. In: Environmental Toxicology and Risk Assessment:
  41. (2001). Mammalian aromatases.
  42. (1985). Masculinization of female mosquitofish by exposure to plant sterols and Mycobacterium smegmatis.
  43. (2001). Masculinization of female mosquitofish in kraft mill effluent-contaminated Fenholloway River water is associated with androgen receptor agonist activity.
  44. (1941). Morphogenesis of the gonopodium in Gambusia affinis affinis.
  45. (1989). Morphological and behavioral characters in mosquitofish as potential bioindication of exposure to kraft mill effluent.
  46. (1999). Morphological masculinization in Poeciliid females from a paper mill effluent receiving tributary of the St.
  47. (1995). New York:Freeman and Company,
  48. (1998). Overview of a workshop on screening methods for detecting potential (anti-) estrogenic/androgenic chemicals in wildlife.
  49. (1978). Phylogenetic distribution of aromatase and other androgen-converting enzymes in the central nervous system.
  50. (1995). Phytoestrogens: epidemiology and a possible role in cancer protection.
  51. (2000). Possible Endocrine Disrupting Effects of Cattle Ranch Effluent on a Sentinel Species. Research Progress Report. Brussels:European Economic Commission,
  52. (1994). Reflections on the thyroidology of fishes: from molecules to humankind.
  53. (1998). Sex-steroid and thyroid hormone concentrations in juvenile alligators (Alligator mississipiensis) from contaminated and reference lakes in Florida,
  54. (1999). Suppression of P450 aromatase gene expression in sex-reversed males produced by rearing genetically female larvae at high water temperature during a period of sex differentiation in the Japanese flounder (Paralichthys olivaceus).
  55. (1991). TBT-induced imposex in the dogwhelk, Nucella lapillus: geographic uniformity of the response and effects.
  56. (1995). The E-SCREEN assay as a tool to identify estrogens: an update on estrogenic environmental pollutants. Environ Health Perspect 103(suppl 7):113–122
  57. (2001). The effects of endocrinedisrupting chemicals on the reproduction and development of wildlife. In:
  58. (2000). Thyroid hormone interactions: mechanisms and biomarkers for endocrine disrupting chemicals [Abstract]. In:
  59. (1996). Tributyltin (TBT) effects on Ocinebrina-Aciculata (Gastropoda, Muricidae)—imposex development, sterilization, sexchange and population decline.
  60. (2001). Two CYP19 (P450 aromatase) genes on duplicated zebrafish chromosomes are expressed in ovary or brain.
  61. (2000). Vitellogenin as a biomarker of exposure for estrogen or estrogen mimics.
  62. (1996). Vitellogenin induction and reduced serum testosterone concentrations in feral male carp (Cyprinus carpio) captured near a major metropolitan sewage treatment plant.
  63. (1998). Widespread sexual disruption in wild fish.

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