Cytogenetic toxicity and gonadal effects of 17 α-methyltestosterone in Astyanax bimaculatus (Characidae) and Oreochromis niloticus (Cichlidae)

Abstract

ABSTRACT. The synthetic hormone, 17-α-methyltestosterone (MT), is used in fish hatcheries to induce male monosex. Androgenic effects on various fish species have been reported; however, few studies have assessed possible genotoxic effects, although there are concerns about such effects in target and non-target species. We evaluated genotoxic and gonadal effects of MT in adult tilapia (Oreochromis niloticus) and Astyanax bimaculatus (a common native non-target fish in Brazil). Fish were fed for 28 days with ration containing MT (60 mg/L), a normal dose used in fish farming. Evaluation of MT genotoxicity was carried out through micronucleus test, nuclear abnormality, and comet assay analyses on peripheral erythrocyte cells collected by cardiac puncture. There were no significant differences in micronucleus frequencies and DNA damage in both species; however, MT caused cytogenetic toxicity in the non-target species, A. bimaculatus, with significantly increased erythrocyte nuclear abnormalities. Histopathological analyses of the female gonads of O. niloticus revealed that MT significantly inhibited the development of mature oocytes, while in A. bimaculatus it provoked Methyltestosterone's genotoxic and gonadal effects significant inhibition of spermatozoa production. We concluded that discharge of fish-hatcheries water onto the surface of aquatic ecosystems should be avoided due to risks to reproduction of native species.

Genotoxic evaluation in Oreochromis niloticus (Fish: Characidae) of recombinant spore–crystal complexes Cry1Ia, Cry10Aa and Cry1Ba6 from Bacillus thuringiensis

“…Thus, moderately damaged comets are those in classes 1 (rate of damage 5-20 %) and 2 (rate of damage 20-40 %), while highly damaged comets are those in classes 3 (rate of damage 40-75 %) and 4 (rate of damage [75 %). This criterion has been used in other publications by our group (Miranda-Vilela et al 2010;Rivero-Wendt et al 2013), as well as by other groups (Cuong et al 2006;Patetsini et al 2013).…”

Lack of genotoxicity in Astyanax bimaculatus and Oreochromis niloticus of 17α-methyltestosterone used in fish hatcheries to produce male monosex populations

“…In our previous study, A. bimaculatus and O. niloticus were exposed for 28 days through food containing MT (60 mg/L), as normally occurs in fish hatcheries. There were no significant increases in MN frequency or comet induction in either species (Rivero-Wendt et al, 2013).…”

Molecular cloning, characterization, and expression profiles of androgen receptors in spotted scat (Scatophagus argus)

“…Based on previous studies on fathead minnow (Wilson et al, 2004), Atlantic croaker (Sperry and Thomas, 2000), and kelp bass (Sperry and Thomas, 1999), AR signal blockage by antiandrogen would cause a significant decrease in aromatase expression in ovaries, and, thus, disrupt the normal endocrine function. Therefore, appropriate sAR expression in the ovaries might be associated with proper ovarian development (Rivero-Wendt et al, 2013b;Liu et al, 2014). Interestingly, sARs were observed to be most abundant in the pituitary of both males and females.…”