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Cryopreservation is an important tool routinely employed in Assisted Reproduction Technologies (ARTs) and germplasm banking. For several years, the assessment of global DNA fragmentation seemed to be enough to ensure the integrity of genetic material. However, cryopreservation can produce molecular alterations in key genes and transcripts undetectable by traditional assays, such modifications could interfere with normal embryo development. We used zebrafish as a model to study the effect of cryopreservation on key transcripts and genes. We employed an optimized cryopreservation protocol for genital ridges (GRs) containing primordial germ cells (PGCs) considered one of the best cell sources for gene banking. Our results indicated that cryopreservation produced a decrease in most of the zebrafish studied transcripts (cxcr4b, pou5f1, vasa and sox2) and upregulation of heat shock proteins (hsp70, hsp90). The observed downregulation could not always be explained by promoter hypermethylation (only the vasa promoter underwent clear hypermethylation). To corroborate this, we used human spermatozoa (transcriptionally inactive cells) obtaining a reduction in some transcripts (eIF2S1, and LHCGR). Our results also demonstrated that this effect was caused by freezing/thawing rather than exposure to cryoprotectants (CPAs). Finally, we employed real-time PCR (qPCR) technology to quantify the number of lesions produced by cryopreservation in the studied zebrafish genes, observing very different vulnerability to damage among them. All these data suggest that molecular alterations caused by cryopreservation should be studied in detail in order to ensure the total safety of the technique.

The cryopreservation of gametes and embryos is a technique widely used in reproductive biology. This technology helps in the reproductive management of domesticated animals, and it is an important tool for gene banking and for human-assisted reproductive technologies. Antifreeze proteins are naturally present in several organisms exposed to subzero temperatures. The ability for these proteins to inhibit ice recrystallization together with their ability to interact with biological membranes makes them interesting molecules to be used in cryopreservation protocols. This mini-review provides a general overview about the use of antifreeze proteins to improve the short and long term storage of gametes and embryos.

SUMMARYSperm cryopreservation is widely used in clinic for insemination, in vitro fertilization and other procedures such as intracytoplasmic sperm injection. The assessment after freezing/thawing of spermatozoa viability, motility and sometimes DNA integrity (mainly using fragmentation assays) has been considered enough to guarantee the safety and effectiveness of the technique. However, it is known that, even when fragmentation is absent, a significant DNA damage could be detected in some genome regions. This is particularly important considering that, during the last years, several studies have pointed out the importance of key paternal genes in early embryo development. In this study, using normozoospermic donors, we present a candidate gene approach in which we quantify the number of lesions produced by freezing/thawing over key genes (PRM1, BIK, FSHB, PEG1/MEST, ADD1, ARNT, UBE3A, SNORD116/PWSAS) using quantitative PCR. Our results demonstrated that the cryopreservation protocol used, which is routinely employed in clinic, produced DNA lesions. The genes studied are differentially affected by the process, and genome regions related to Prader-Willi and Angelman syndromes were among the most damaged: SNORD116/PWSAS (4.56 AE 1.84 lesions/10 kb) and UBE3A (2.22 AE 1.3 lesions/10 kb). To check if vitrification protocols could reduce these lesions, another experiment was carried out studying some of those genes with higher differences in the first study (FSHB, ADD1, ARNT and SNORD116/PWSAS). The number of lesions was not significantly reduced compared to cryopreservation. These results could be relevant for the selection of the most adequate available cryopreservation protocol in terms of the number of lesions that produced over key genes, when no differences with other traditional techniques for DNA assessment could be detected.

The objective of this study is to analyse the effect of the ingestion of two selected antioxidant probiotics strains (Lactobacillus rhamnosus CECT8361 and Bifidobacterium longum CECT7347) on sperm quality parameters in asthenozoospermic males after three and six weeks of administration. Nine asthenozoospermic men without any medical treatment under similar diet conditions participated in the study. The quality of individual sperm samples was evaluated before (previous to ingestion), during (after 3 and 6 weeks of ingestion) and after probiotic administration (3 and 6 weeks after finishing the treatment). Sperm motility was evaluated by computer-assisted sperm analysis system, DNA fragmentation by sperm chromatin structure assay, cell viability by flow cytometry and measurement of intracellular HO (reactive oxygen species; ROS) by flow cytometry using dichloro-dihydrofluorescein diacetate. Sperm motility was drastically improved after the treatment (approximately 6 fold change), DNA fragmentation was statistically reduced after probiotic administration from (approximately 1.2 fold change) and intracellular HO level was decreased (approximately 3.5 fold change). Cell viability was not affected by the treatment. The significant improvement in sperm motility and the decrease in DNA fragmentation reported in this study provide preliminary evidence that probiotics could be administrated to improve motility and decrease DNA fragmentation and ROS levels in asthenozoospermic human males.

Background: Vitamin K (VK) is a fat-soluble vitamin better known for its essential role in blood coagulation, but its involvement in a range of other biological processes is not yet fully understood. Methods: Here we explore the potential role of VK in reproduction in a fish teleost model species, the Senegalese sole (Solea senegalensis), showing male reproductive dysfunction by means of biochemistry, transcriptomic and bioinformatics analysis. Results: Fish fed with dietary VK supplementation had increased testosterone plasma levels and lower sperm DNA fragmentation in males. Using a transcriptomic approach, small non-coding RNAs (sncRNAs) from blood plasma were sequenced and several differentially expressed sncRNAs (2 piRNAs and 7 miRNAs transcripts) were associated with nutritional status and/or better sperm quality. Bioinformatic analyses of predicted mRNAs targeted by sncRNAs revealed that they may be involved in blood coagulation and gonadotropin-releasing hormone pathways, among other processes. Conclusions: Present results suggest an unexpected and complex regulation of the nutritional status and reproductive performance at the level of the whole organism through circulating sncRNAs.

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