EXPRESSION OF PL10 PROTEIN IN MALE GERM CELLS OF PODARCIS SICULA (REPTILIA, LACERTIDAE) DURING THE REPRODUCTIVE-CYCLE PHASES

PL10 is a DEAD-box protein that functions as ATP-dependent RNA helicase. DEAD-box proteins are involved in many processes related to RNA metabolism. In particular, some of them regulate the translation of multiple mRNAs allowing specific molecules to direct the process of differentiation in male and female germ cells. VASA, PL10, and P68 DEAD-box proteins are members of three closely related subfamilies: Vasa, in several animals, is exclusively expressed to the germ cell lineage, while PL10 and P68 expression are documented also in somatic tissues. In mouse, three PL10 related genes are identified: DDX3 and DDX3Y located on chromosomes X and Y and expressed in germ and somatic cells and the autosomal retrogene PL10 specifically expressed in testicular tissues at the pachytene stage of male meiosis. In non-mammal animals, PL10 is the sole member of the subfamily and in Xenopus and in Danio rerio PL10 expression is well documented in male and female germ cells but also in most embryonic and adult tissues. At the moment, there is no available data regarding PL10 in reptiles. We isolated Podarcis sicula PL10 homologue gene (Ps-PL10), developed a specific antibody (anti-Ps-PL10) and analyzed, at confocal microscopy, the expression pattern of PL10 during spermatogenesis in all phases of adult reproductive cycle of P. sicula (1- full gonadal activity in the spring, 2- complete regression in the summer, and 3- slow autumnal recrudescence without spermiation) with the aim to identify when PL10 is expressed during the differentiation process of male germ cells. Moreover, to verify if this protein is also expressed in the somatic tissue of the testis, this analysis was extend to young testes when the walls of the seminiferous tubules were forming. The obtained results show that PL10 expression is present from spermatocytes I to spermatids. During full gonadal activity (spring), PL10 expression increases in spermatids in the final steps of spermiogenesis, the strong immunostaining accumulates in the cytoplasm of residual bodies. No stained is observed in spermatogonia and in spermatozoa as well as in the somatic cells of seminiferous epithelium in all phases of the reproductive cycle analyzed. The specific expression of PL10 in meiotic cells suggests that this protein is involved in the differentiation of germ cells, in particular, during the differentation process from spermatid to spermatozoa, given the massive expression observed in the cytoplasm of residual bodies.