Selenium is an important dietary micronutrient and an essential component of selenoproteins and the active sites of some enzymes, although at high concentrations it is toxic. We investigated diphenyl diselenide ((C6H5)2Se2 ) for its effects on the developmental stages of Drosophila melanogaster and found that in the larval and pupae stages the toxic threshold for this compound when added to the banana-agar medium on which the larva were fed was 350 µmol. In adult flies, fed on the same media, there were no observable toxic effects below 500 µmol but there were toxic effects above 600 µmol, indicating that adult flies were more resistant to selenium intoxication. In larvae, a when diphenyl diselenide was present above the toxic threshold there was increased activation of the hsp83 heat shock protein gene. Selenium promotes oxidation of sulfhydryl groups and affects the folding of proteins and this could explain the over-expression of hsp83 because the product of this gene is involved in protein folding and defense responses, including the response to heat shock.

RESUMO Hermafroditismo e pseudo-hermafroditismo são fenômenos relativamente raros em cães. Descreve-se aqui um possível caso de pseudo-hermafroditismo masculino. O cão em estudo apresentava genitália ambígua, sendo tratado até os quatro meses de idade como fêmea. O estudo da cromatina do X em mucosa bucal foi negativo e o cariótipo de sangue periférico apresentou 78, XY cromossomos. A análise radiológica evidenciou uma uretra de trajeto feminino e a presença de uma estrutura piriforme compatível com vagina cranial, o que justificava a presença de incontinência urinária. Com relação a aspectos etológicos, o animal manifestava comportamento masculino.

SUMMARY Hermaphroditism and pseudohermaphroditism are relatively rare phenomenon in dogs. A possible case of male pseudohermaphroditism is described here. The studied dog showed ambiguos genitalia pseudohermaphroditism and was thought to be a female until four months of age. The X-chromatin in cells of buccal smears was negative, and the karyotype of peripheric blood had 78,XY, chromosomes. Radiological analysis revealed an urethra with feminine course and the presence of one piriform structure compatible with cranial vagine, that could explain the urynary incontinence. Concerning the ethological aspects, this dog showed male behavior.