Canonical and cellular pathways timing gamete release in Acropora digitifera, Okinawa, Japan

Natural light cycles are important for synchronizing behavioural and physiological rhythms over varying time periods in both plants and animals. An endogenous clock, regulated by positive and negative elements, interacting in feedback loops controls these rhythms. Many corals exhibit diel cycles of polyp expansion and contraction entrained by solar light patterns and monthly cycles of spawning or planulation that correspond to nocturnal lunar light cycles. However, despite considerable interest in studies of coral reproduction, there is currently not enough molecular information about the cellular pathways involved with synchronizing spawning/planulation in broadcast spawners and brooders. To determine whether the endogenous clock is implicated in the regulation of reproductive behaviour in corals, we characterized the transcriptome of Acropora digitifera colonies at twelve time points over a 2-month period of full and new moons, starting with the day of spawning in June 2014. We identified 608 transcripts with differential expression only on the spawning night during the coral setting phase and gamete release. Our data revealed an upregulation of light-sensing molecules and rhodopsin-like receptors that initiate signalling cascades, including the glutamate, SMAD signalling and WNT signalling pathways, neuroactive ligand-receptor interactions and calcium signalling. These are all involved in cell cycling, cell movement, tissue polarity, focal adhesion and cytoskeleton reorganization and together lead to gamete release. These findings can improve the understanding of many time-based cycles and extend our knowledge of the interplay between exogenous signals and the endogenous clock in cnidarians.

BRDT gene sequence in human testicular pathologies and the implication of its single nucleotide polymorphism (rs3088232) on fertility

Bromodomain testis-specific (BRDT) protein is essential for the normal process of spermatogenesis. Mutant mice that expressed truncated BRDT had impaired testicular histology with severely reduced sperm concentration and abnormal sperm morphology, while a model of knockout Brdt mice with no BRDT protein had complete meiotic arrest. A BRDT single nucleotide polymorphism (SNP) (rs3088232) was reported as being associated with infertility in men. We assessed testicular specimens of 276 azoospermic men who underwent testicular sperm extraction to search for specimens that showed spermatogenic impairments similar to those of mutant BRDT mice. Ten similar specimens were selected for BRDT gene sequencing and they revealed three NCBI-reported SNPs (rs10783071, rs3088232 and rs10747493) variously distributed among them. Bioinformatics analysis predicted that they would not affect protein activity. Further assessment of rs3088232 frequency in a large group of non-obstructive azoospermia men and fertile controls demonstrated no significant difference between them (27.2 and 21.7% respectively; p = 0.122, Fisher's exact test). We conclude that the testicular impairments observed in the 10 specimens were not a consequence of BRDT gene mutation. The association between BRDT rs3088232 and infertility that had been reported in other studies was not supported.