Bcl-2 and Caspase 3 mRNA levels in the testes of gudgeon, Gobio gobio, exposed to ethinylestradiol (EE2).
Apoptosis inhibition has been reported in the male reproductive tract of teleost fish exposed to 17beta-estrogen or estrogen-like compounds. In order to understand the molecular mechanisms of cell death inhibition, this study examined 2 genes involved in the apoptotic pathway, Bcl-2 and Caspase 3, an anti-apoptotic and a pro-apoptotic genes, respectively. Partial cDNA sequences of Bcl-2 and Caspase 3 were cloned from gudgeon (Gobio gobio), a common European cyprinid fish. To follow mRNA levels of Bcl-2 and Caspase 3 under xenoestrogen exposure, we first performed an in vitro experiment on fish testis exposed to the most potent xenoestrogen found in the environment, ethinylestradiol (EE2). We further studied mRNA expression of both genes in the testis of fish exposed to xenoestrogens in situ. In the in vitro experiment, fragments of gudgeon testis were exposed for 21 days to 10(-3), 10(-2), 10(-1), 1 and 10 microg/L of EE2, as well as to positive (10(-1) microg/L of E2) and ethanol control medium. Results showed a significant induction of Bcl-2 mRNA at 10(-1) microg/L (p<0.05). Surprisingly, Caspase 3, a cell death effector, displayed the same profile as observed for the anti-apoptotic gene Bcl-2. In the experiment on wild gudgeon exposed from birth to an estrogenic sewage treatment plant effluent, the mRNA expression of Bcl-2 and Caspase 3 in feminized fish (ovotestis) was not significantly different due to high variability of expression between individuals. At the current state of knowledge on spermatogenesis disruption in teleost fish, in vitro studies seem better adapted than in situ investigations to enlighten the molecular pathway of apoptosis inhibition in testis exposed to xenoestrogens.
Nadzialek
Stéphanie
S
The University of Namur (FUNDP), Unité de Recherche en Biologie des Organismes (URBO), 61 rue de Bruxelles, B-5000 Namur, Belgium.
Pigneur
Lise-Marie
LM
The University of Namur (FUNDP), Unité de Recherche en Biologie des Organismes (URBO), 61 rue de Bruxelles, B-5000 Namur, Belgium.
Wéron
Benjamin
B
The University of Namur (FUNDP), Unité de Recherche en Biologie des Organismes (URBO), 61 rue de Bruxelles, B-5000 Namur, Belgium.
Kestemont
Patrick
P
The University of Namur (FUNDP), Unité de Recherche en Biologie des Organismes (URBO), 61 rue de Bruxelles, B-5000 Namur, Belgium. Electronic address: patrick.kestemont@fundp.ac.be.
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D053148:Caspase 3 / Q000235:genetics*; D003530:Cyprinidae / Q000235:genetics* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000009:adverse effects; D004967:Estrogens / Q000633:toxicity; D004997:Ethinyl Estradiol / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects*; D019254:Genes, bcl-2 / Q000235:genetics*; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013091:Spermatogenesis / Q000187:drug effects; D013737:Testis / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D004967:Estrogens; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D053148:Caspase 3