Reproductive expression dynamics and comparative toxicological perspective of beta estrogen receptor gene in the male wall lizard, Podarcis sicula Rafinesque, 1810 (Chordata: Reptilia)

Abstract

Over the last few decades, due to its relevant function in male reproduction assessment, important molecular achievements have been made in the molecular characterization of estrogen receptor genes in various species. Our work focuses on a male seasonal breeder, the bioindicator Podarcis sicula, because of its peculiar gonadal anatomy, similar to that of humans. Based on the cloned lizard’s gene sequence fragment of estrogen receptor beta, esr2 (GenBank JN705543.1), we found DNA binding domain identity of 99% as well as a homologous sequence with humans. Furthermore, in order to better illustrate how this gene is regulated in the lizard’s reproductive system organs, we investigated the transcriptional activity of esr2 in brain and testis tissues during mating and winter stasis phases of the reproductive cycle. Quantitative real time-polymerase chain reaction (qRT-PCR) analyses performed on male gonadal tissues demonstrate a significant increase in esr2 expression during mating compared to the winter stasis period, while in the brain, esr2 shows the opposite trend. Next, we provide morphological evidence of the detrimental effect on spermatogenesis of a pure anti-estrogen treatment (ICI 182,780) and the corresponding effect on esr2 expression in lizard specimens during the mating period which, upon treatment, was found to be no different from the expression levels in winter stasis both in the brain and in the testis. In this study, we explore the potential use of Podarcis sicula as a model for human testis development and maturation, as well as esr2 expression for toxicological screening in one-testis gonadectomy.

Keywords

• esr2 phylogenetic similarity
• Podarcis sicula
• qRT-PCR
• ICI 182
• 780
• toxicological assessment