EFFECT OF ANTI-ANDROGENIC SUBSTANCES ON THE SEXUAL REPRODUCTION OF ROTIFERS : IMPACTS ON BRACHIONUS CALYCIFLORUS MALE FERTILITY

Abstract

Many substances released in aquatic ecosystems have been reported to disrupt endocrine systems in vertebrates and invertebrates. In the rotifer Brachionus calyciflorus, studies show that chemicals characterized by a high affinity to the vertebrate androgen receptor depress sexual reproduction at concentrations one to two orders of magnitude below those that affect asexual reproduction. We studied the effect of cyproterone acetate, an anti-androgen of steroid like structure, and of the pesticide fenitrothion, a non steroidal molecular which has a high affinity to the vertebrate androgen receptor, on the sexual reproduction of rotifers. In mating experiments we crossed control females with exposed males and vice versa to determine whether anti-androgens affected males, females or both. Fertilization rate and number of resting eggs produced were affected by both substances tested. With fenitrothion, depression of these endpoints was observed exclusively when males were treated. Cyproterone acetate enhanced production of resting eggs whereas fertilization rate was not significantly affected. Increased production of resting eggs was observed both with treated females and males. Parameters of male fertility were compared in control and in exposed males. We report impacts on spermatozoa numbers, morphology and fertilizing potential, and on male morphology, longevity and mating behaviour for the two substances tested