The aging male: Relationship between male age, sperm quality and sperm DNA damage in an unselected population of 3124 men attending the fertility centre for the first time.

OBJECTIVE: the aim of our study was to put forward insights to treat any possible correlation among sperm quality, sperm DNA damage and male age as they may have fertility implications for men who choose to delay fatherhood. MATERIALS AND METHODS: Our study is a non-interventional retrospective analysis of 3124 semen samples from patients that were investigated for the conventional semen parameters. Tunel test assay was set up for the evaluation of the sperm DNA fragmentation index (DFI). We applied the Kappa index to compare both the 1999 and the 2010 World Health Organization (WHO) reference criteria to evaluate the competence of such semen parameters categorization during the standard routine of our laboratory. RESULTS: With regards to our findings, it is possible to underline a significant relationship between aging and semen volume (p = 0.001), motility (p = 0.009), semen viscosity (p < 0.003) and sperm DNA damage (p < 0.009). We found a trend when focusing on the semen concentration (p = 0.05). The analysis of sperm morphology did not show any influence with advancing age (p = 0.606). When comparing both the 1999 and the 2010 WHO scales we found no accordance in the appraisal of sperm morphology but a very good one in the evaluation of the other parameters. CONCLUSIONS: Conventional semen analysis represents the opportunity to draw up a proxy insight on the male fertility status even if semen quality can only indirectly assess the probability of pregnancy. Several studies have verified a decay in the male reproductive system, sperm quality and fertility with advancing age although the reported results are not yet conclusive. Our results substantially agree with those findings outlined in the literature. Moreover we find that the discrepancy between the two WHO reference scales would eventually lead to an improper diagnosis of infertility.

Genomic organization and splicing evolution of the doublesex gene, a Drosophila regulator of sexual differentiation, in the dengue and yellow fever mosquito Aedes aegypti.

BACKGROUND: In the model system Drosophila melanogaster, doublesex (dsx) is the double-switch gene at the bottom of the somatic sex determination cascade that determines the differentiation of sexually dimorphic traits. Homologues of dsx are functionally conserved in various dipteran species, including the malaria vector Anopheles gambiae. They show a striking conservation of sex-specific regulation, based on alternative splicing, and of the encoded sex-specific proteins, which are transcriptional regulators of downstream terminal genes that influence sexual differentiation of cells, tissues and organs. RESULTS: In this work, we report on the molecular characterization of the dsx homologue in the dengue and yellow fever vector Aedes aegypti (Aeadsx). Aeadsx produces sex-specific transcripts by alternative splicing, which encode isoforms with a high degree of identity to Anopheles gambiae and Drosophila melanogaster homologues. Interestingly, Aeadsx produces an additional novel female-specific splicing variant. Genomic comparative analyses between the Aedes and Anopheles dsx genes revealed a partial conservation of the exon organization and extensive divergence in the intron lengths. An expression analysis showed that Aeadsx transcripts were present from early stages of development and that sex-specific regulation starts at least from late larval stages. The analysis of the female-specific untranslated region (UTR) led to the identification of putative regulatory cis-elements potentially involved in the sex-specific splicing regulation. The Aedes dsx sex-specific splicing regulation seems to be more complex with the respect of other dipteran species, suggesting slightly novel evolutionary trajectories for its regulation and hence for the recruitment of upstream splicing regulators. CONCLUSIONS: This study led to uncover the molecular evolution of Aedes aegypti dsx splicing regulation with the respect of the more closely related Culicidae Anopheles gambiae orthologue. In Aedes aegypti, the dsx gene is sex-specifically regulated and encodes two female-specific and one male-specific isoforms, all sharing a doublesex/mab-3 (DM) domain-containing N-terminus and different C-termini. The sex-specific regulation is based on a combination of exon skipping, 5' alternative splice site choice and, most likely, alternative polyadenylation. Interestingly, when the Aeadsx gene is compared to the Anopheles dsx ortholog, there are differences in the in silico predicted default and regulated sex-specific splicing events, which suggests that the upstream regulators either are different or act in a slightly different manner. Furthermore, this study is a premise for the future development of transgenic sexing strains in mosquitoes useful for sterile insect technique (SIT) programs.