Sexual characteristics are altered by 4-tert-octylphenol and 17 beta-estradiol in the adult male guppy (Poecilia reticulata)

Endocrine-disrupting chemicals (EDCs) are believed to interfere with animal reproduction, but only few biomarkers above the cellular level have been d eveloped to assess the. adverse effects of these chemicals. Using the guppy (Poecilia reticulata) as a model organism, studies have been undertaken wi th the object of comparing biomarker responses to EDCs at increasing levels of biological complexity. Short-term exposure to the xenoestrogen 4-tert-o ctylphenol and the natural estrogen 17 beta -estradiol (E2) changed importa nt sexual characteristics in the adult male guppy. Both compounds increased the number of sperm cells in the ejaculates, reduced the area and color in tensity of the sexually attractive orange spots, and inhibited testis growt h. In the case of E2, the effects on sperm count and coloration were still evident after 3 months of recovery in clean water. Preliminary results on m ale reproductive capability demonstrated that treated males produced fewer offspring than untreated fish, indicating an impairment of reproduction its elf. (C) 2001 Academic Press.