Programmed Death-Ligand (PD-L1), Epidermal Growth Factor (EGF), Relaxin, and Matrix Metalloproteinase-3 (MMP3): Potential Biomarkers of Malignancy in Canine Mammary Neoplasia.

Gene expression has been suggested as a putative tool for prognosis and diagnosis in canine mammary neoplasia (CMNs). In the present study, 58 formalin-fixed paraffin-embedded (FFPE) paraffined canine mammary neoplasias from 27 different bitches were included. Thirty-seven tumours were classified as benign, whereas thirty-one were classified as different types of canine carcinoma. In addition, mammary samples from three healthy bitches were also included. The gene expression for vascular endothelial growth factor-α (VEGFα), CD20, progesterone receptor (PGR), hyaluronidase-1 (HYAL-1), programmed death-ligand 1 (PD-L1), epidermal growth factor (EGF), relaxin (RLN2), and matrix metalloproteinase-3 (MMP3) was assessed through RT-qPCR. All the assessed genes yielded a higher expression in neoplastic mammary tissue than in healthy tissue. All the evaluated genes were overexpressed in neoplastic mammary tissue, suggesting a role in the process of tumorigenesis. Moreover, PD-L1, EGF, relaxin, and MMP3 were significantly overexpressed in malignant CMNs compared to benign CMNs, suggesting they may be useful as malignancy biomarkers.

Canine Mammary Neoplasia Induces Variations in the Peripheral Blood Levels of CD20, CD45RA, and CD99.

The idea of using tumour biomarkers as diagnostic tools is progressively increasing. Of these, serum biomarkers are of particular interest, as they can provide rapid results. In the present study, serum samples from 26 bitches diagnosed with mammary tumours, plus 4 healthy bitches, were obtained. The samples were analysed using CD antibody microarrays targeting 90 CD surface markers and 56 cytokines/chemokines. A total of five CD proteins, namely CD20, CD45RA, CD53, CD59, and CD99, were selected and further analysed, utilizing immunoblotting techniques to validate the microarray results. CD45RA showed a significantly lower abundance in the serum samples from the bitches carrying mammary neoplasia in comparison to the healthy animals. Regarding CD99, the serum samples from the neoplastic bitches showed it in a significantly higher abundance than those from the healthy patients. Finally, CD20 showed a significantly higher abundance in bitches carrying a malignant mammary tumour in comparison to healthy patients, but no differential expression between malignant and benign tumours was observed. According to these results, both CD99 and CD45RA are indicators of mammary tumour presence, but without distinguishing between malignant and benign.

A systems biology framework integrating GWAS and RNA-seq to shed light on the molecular basis of sperm quality in swine.

BACKGROUND: Genetic pressure in animal breeding is sparking the interest of breeders for selecting elite boars with higher sperm quality to optimize ejaculate doses and fertility rates. However, the molecular basis of sperm quality is not yet fully understood. Our aim was to identify candidate genes, pathways and DNA variants associated to sperm quality in swine by analysing 25 sperm-related phenotypes and integrating genome-wide association studies (GWAS) and RNA-seq under a systems biology framework. RESULTS: By GWAS, we identified 12 quantitative trait loci (QTL) associated to the percentage of head and neck abnormalities, abnormal acrosomes and motile spermatozoa. Candidate genes included CHD2, KATNAL2, SLC14A2 and ABCA1. By RNA-seq, we identified a wide repertoire of mRNAs (e.g. PRM1, OAZ3, DNAJB8, TPPP2 and TNP1) and miRNAs (e.g. ssc-miR-30d, ssc-miR-34c, ssc-miR-30c-5p, ssc-miR-191, members of the let-7 family and ssc-miR-425-5p) with functions related to sperm biology. We detected 6128 significant correlations (P-value ≤ 0.05) between sperm traits and mRNA abundances. By expression (e)GWAS, we identified three trans-expression QTL involving the genes IQCJ, ACTR2 and HARS. Using the GWAS and RNA-seq data, we built a gene interaction network. We considered that the genes and interactions that were present in both the GWAS and RNA-seq networks had a higher probability of being actually involved in sperm quality and used them to build a robust gene interaction network. In addition, in the final network we included genes with RNA abundances correlated with more than four semen traits and miRNAs interacting with the genes on the network. The final network was enriched for genes involved in gamete generation and development, meiotic cell cycle, DNA repair or embryo implantation. Finally, we designed a panel of 73 SNPs based on the GWAS, eGWAS and final network data, that explains between 5% (for sperm cell concentration) and 36% (for percentage of neck abnormalities) of the phenotypic variance of the sperm traits. CONCLUSIONS: By applying a systems biology approach, we identified genes that potentially affect sperm quality and constructed a SNP panel that explains a substantial part of the phenotypic variance for semen quality in our study and that should be tested in other swine populations to evaluate its relevance for the pig breeding sector.

Semen quality and freezability analysis during breeding and non-breeding seasons in heavy draft stallions in southern Chile.

The aim of this study was to evaluate seasonal changes in basic parameters of sperm quality and freezability behaviour of ejaculates from 10 fertile heavy draft stallions. A total of 140 ejaculates were collected, processed and evaluated during both the breeding (September-November) and non-breeding seasons (April-June). Fresh semen was evaluated for volume, concentration, total spermatozoa per ejaculate, plasma membrane integrity and total sperm motility. Cryopreserved samples were evaluated for plasma membrane integrity and sperm motility by the CASA system, and for the freezability index (FI), which was defined as the decreased ratio of viability after freezing-thawing. In fresh ejaculates, only viability showed significantly higher values in the breeding than in the non-breeding season (64.0% ± 15.0% vs. 58.6% ± 12.0%, respectively; p < .05). The sperm post-thawing analysis of viability and total motility parameters showed no significant changes linked to the season. However, the FI analysis showed that the ejaculates collected in the non-breeding season had higher cryoresistance characteristics than those collected in the breeding season. Results suggest that the presence of some cryoprotective factor/s in heavy draft horse ejaculates could be modulated by seasonality, with higher protective effects in the non-breeding season.

Tyrosine phosphorylation is not a relevant mechanism to modulate aquaporin 2 activity in gestational queen endometrium and placenta.

Aquaporins have been shown to be regulated by phosphorylation of serine residues, but the possible role of tyrosine residues phosphorylation has not been evaluated. Changes in the localization of aquaporin 2 (AQP2) in the queen endometrium have been related to serum progesterone levels. The aim of this study was to determine whether these AQP2-localization changes are mediated by variations in its tyrosine phosphorylation levels. Twelve queens were included in the study and divided into (a) non-macroscopically pregnant with low levels of progesterone; (b) non-macroscopically pregnant with high levels of progesterone; (c) 30 days of pregnancy; and (d) 60 days of pregnancy. Samples from endometrium and placental transference zone were obtained, immunoprecipitated and analysed by immunoblotting to determine the abundance of AQP2 and its relative levels of tyrosine phosphorylation. No significant differences in the tyrosine phosphorylation levels of immunoprecipated-AQP2 were observed between groups. We can thus conclude that changes in the localization of AQP2 in the queen endometrium are not modulated by tyrosine phosphorylation.

"In vitro" capacitation and further progesterone-induced acrosome exocytosis are linked to specific changes in the expression and location of threonine phosphorylation of boar spermatozoa.

The aim of this study was to determine if the achievement of the "in vitro" capacitation (IVC) status and subsequent progesterone-induced "in vitro" acrosome exocytosis (IVAE) was accompanied with overall changes in threonine phosphorylation (pThre) of boar spermatozoa. For this purpose, mono- and bi-dimensional Western blot analyses as well as immunocytochemistry studies against pThre were performed in boar sperm subjected to IVC and subsequent IVAE. Mono-dimensional Western blot in non-capacitated samples showed that launching of IVC did induce an overall increase in signal intensity in all observed bands that was followed by a subsequent decrease afterwards. Bi-dimensional Western blot analysis showed the presence of four main signal protein clusters. The attainment of IVC induced an overall decrease in the number and intensity of spots of Clusters A, B and C and a concomitant increase in the intensity of spots of Cluster D. The IVAE launching caused a rapid increase in the intensity of spots of Clusters B, C and D, which was followed by a subsequent decrease of the intensity together with a concomitant pI displacement of Cluster C. Finally, immunocytochemistry showed that the pThre signal of non-capacitated cells was located at the whole sperm. The IVC did not induce prominent changes in this location. In contrast, the induction of IVAE caused the appearance of an additional an intense acrosome and tail pThre signal that subsequently decreased. In conclusion, our results indicate that IVC and further IVAE induced specific changes in the intensity and appearance of pThre protein phosphorylation which were linked to changes of specific protein characteristics as pI. These results support, thus, the existence of a specific role of pThre in IVC/IVAE of boar sperm.

Use of hypometabolic TRIS extenders and high cooling rate refrigeration for cryopreservation of stallion sperm: presence and sensitivity of 5' AMP-activated protein kinase (AMPK).

This study evaluated the effect of the use of hypometabolic TRIS extenders in the presence or the absence of AMPK activators as well as the utilization of high cooling rates in the refrigeration step on the freezability of stallion sperm. Twelve ejaculates were cryopreserved using Botucrio® as a control extender and a basic TRIS extender (HM-0) separately supplemented with 10 mM metformin, 2mM 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside (AICAR), 2 mM Adenosine monophosphate (AMP), 40 µM compound C AMPK inhibitor or 2 mM AMP+40 µM compound C. Our results showed that the utilization of a hypometabolic TRIS extender supplemented or not with AMP or metformin significantly improves stallion sperm freezability when compared with a commercial extender. Additionally, high cooling rates do not affect stallion sperm quality after cooling and post-thawing. Finally, stallion spermatozoa present several putative AMPK sperm isoforms that do not seem to respond to classical activators, but do respond to the Compound C inhibitor.

Micrococcal nuclease sequencing of porcine sperm suggests enriched co-location between retained histones and genomic regions related to semen quality and early embryo development.

The mammalian spermatozoon has a unique chromatin structure in which the majority of histones are replaced by protamines during spermatogenesis and a small fraction of nucleosomes are retained at specific locations of the genome. The sperm's chromatin structure remains unresolved in most animal species, including the pig. However, mapping the genomic locations of retained nucleosomes in sperm could help understanding the molecular basis of both sperm development and function as well as embryo development. This information could then be useful to identify molecular markers for sperm quality and fertility traits. Here, micrococcal nuclease digestion coupled with high throughput sequencing was performed on pig sperm to map the genomic location of mono- and sub-nucleosomal chromatin fractions in relation to a set of diverse functional elements of the genome, some of which were related to semen quality and early embryogenesis. In particular, the investigated elements were promoters, the different sections of the gene body, coding and non-coding RNAs present in the pig sperm, potential transcription factor binding sites, genomic regions associated to semen quality traits and repeat elements. The analysis yielded 25,293 and 4,239 peaks in the mono- and sub-nucleosomal fractions, covering 0.3% and 0.02% of the porcine genome, respectively. A cross-species comparison revealed positional conservation of the nucleosome retention in sperm between the pig data and a human dataset that found nucleosome enrichment in genomic regions of importance in development. Both gene ontology analysis of the genes mapping nearby the mono-nucleosomal peaks and the identification of putative transcription factor binding motifs within the mono- and the sub- nucleosomal peaks showed enrichment for processes related to sperm function and embryo development. There was significant motif enrichment for Znf263, which in humans was suggested to be a key regulator of genes with paternal preferential expression during early embryogenesis. Moreover, enriched positional intersection was found in the genome between the mono-nucleosomal peaks and both the RNAs present in pig sperm and the RNAs related to sperm quality. There was no co-location between GWAS hits for semen quality in swine and the nucleosomal sites. Finally, the data evidenced depletion of mono-nucleosomes in long interspersed nuclear elements and enrichment of sub-nucleosomes in short interspersed repeat elements.These results suggest that retained nucleosomes in sperm could both mark regulatory elements or genes expressed during spermatogenesis linked to semen quality and fertility and act as transcriptional guides during early embryogenesis. The results of this study support the undertaking of ambitious research using a larger number of samples to robustly assess the positional relationship between histone retention in sperm and the reproductive ability of boars.

Characterization of the Impact of Density Gradient Centrifugation on the Profile of the Pig Sperm Transcriptome by RNA-Seq.

RNA-Seq data from human semen suggests that the study of the sperm transcriptome requires the previous elimination from the ejaculates of somatic cells carrying a larger load of RNA. Semen purification is also carried to study the sperm transcriptome in other species including swine and it is often done by density gradient centrifugation to obtain viable spermatozoa from fresh ejaculates or artificial insemination doses, thereby limiting the throughput and remoteness of the samples that can be processed in one study. The aim of this work was to evaluate the impact of purification with density gradient centrifugation by BoviPureTM on porcine sperm. Four boar ejaculates were purified with BoviPureTM and their transcriptome sequenced by RNA-Seq was compared with the RNA-Seq profiles of their paired non-purified sample. Seven thousand five hundred and nineteen protein coding genes were identified. Correlation, cluster, and principal component analysis indicated high-although not complete-similarity between the purified and the paired non-purified ejaculates. 372 genes displayed differentially abundant RNA levels between treatments. Most of these genes had lower abundances after purification and were mostly related to translation, transcription and metabolic processes. We detected a significant change in the proportion of genes of epididymal origin within the differentially abundant genes (1.3%) when compared with the catalog of unaltered genes (0.2%). In contrast, the proportion of testis-specific genes was higher in the group of unaltered genes (4%) when compared to the list of differentially abundant genes (0%). No proportion differences were identified for prostate, white blood, lymph node, tonsil, duodenum, skeletal muscle, liver, and mammary gland. Altogether, these results suggest that the purification impacts on the RNA levels of a small number of genes which are most likely caused by the removal of epididymal epithelial cells but also premature germinal cells, immature or abnormal spermatozoa or seminal exosomes with a distinct load of RNAs.

Uterine and placental specific localization of AQP2 and AQP8 is related with changes of serum progesterone levels in pregnant queens.

Aquaporins play vital roles in reproductive physiology. This study evaluates the expression and localization dynamics of AQP1, AQP2, AQP3 and AQP8 in the endometrium and placental transference zone during pregnancy in queens by means of immunohistochemistry and Western blot. Animals were distributed into six groups: non-pregnant queens with low levels of serum progesterone (P4), non-pregnant animals with high P4 levels, and queens at 30, 40, 50 and 60 days of pregnancy. All AQPs were present in glandular and luminal epithelia and myometrium. AQP1 was also present in the endometrial endothelia. AQP2, AQP3 and AQP8 were found in trophoblast. In endometrial samples with P4 above 2 ng/mL, AQP2 and AQP8 were distributed across plasma membrane and cytoplasm, whereas progesterone levels under 1 ng/mL kept both AQPs confined to the plasma membrane. Western blot showed no significant changes in AQPs expression among the stages. In conclusion, our results indicate that the distribution of AQP2 and AQP8 in the queen reproductive tract is related to P4 levels.

Identification of circular RNAs in porcine sperm and evaluation of their relation to sperm motility.

Circular RNAs (circRNAs) are emerging as a novel class of noncoding RNAs which potential role as gene regulators is quickly gaining interest. circRNAs have been studied in different tissues and cell types across several animal species. However, a thorough characterization of the circRNAome in ejaculated sperm remains unexplored. In this study, we profiled the sperm circRNA catalogue using 40 porcine ejaculates. A complex population of 1,598 circRNAs was shared in at least 30 of the 40 samples. Generally speaking, the predicted circRNAs presented low abundances and were tissue-specific. Around 80% of the circRNAs identified in the boar sperm were reported as novel. Results from abundance correlation between circRNAs and miRNAs together with the prediction of microRNA (miRNA) target sites in circRNAs suggested that circRNAs may act as miRNA sponges. Moreover, we found significant correlations between the abundance of 148 exonic circRNAs and sperm motility parameters. Two of these correlations, involving ssc_circ_1458 and ssc_circ_1321, were confirmed by RT-qPCR using 36 additional samples with extreme and opposite sperm motility values. Our study provides a thorough characterization of circRNAs in sperm and suggests that circRNAs hold potential as noninvasive biomarkers for sperm quality and male fertility.

In vitro assessment of egg yolk-, soya bean lecithin- and liposome-based extenders for cryopreservation of dairy bull semen.

The study was conducted to compare the effect of four commercially available extenders (Triladyl®- egg yolk-based; Andromed® and Bioxcell®-plant based and Optixcell®-liposome-based) on post-thaw sperm quality and functionality variables evaluated using computer-assisted sperm analysis and flow cytometry. A total of 30 ejaculates from five bulls were analysed. With use of Triladyl®, sperm had a greater post-thaw total motility than with use of Bioxell® and Optixcell® but there was no difference as compared with use of Andromed® with the greatest (P < 0.05) percentage of progressively motile cells. With use of Optixcell®, there was a greater (P < 0.05) percentage of sperm with an intact membrane than with use of Triladyl® and Bioxcell®, but values were similar with use of Andromed®. Acrosome damage in semen preserved with use of Optixcell® was less than with use of Bioxcell® and Andromed®. With use of Optixcell®, there was a greater percentage of viable spermatozoa with a lesser lipid disruption (P < 0.05) when compared with the other extenders. Production of peroxides was greater for sperm cryopreserved with use of Triladyl® and Optixcell® while less superoxide was produced in the samples cryopreserved with the egg yolk-based extender. Optixcell® appears to be a promising alternative to replace traditional egg yolk extenders. With use of Optixcell®, however, there were greater peroxide concentrations after thawing. With use of Andromed®, there were similar results as with use of Optixcell®, therefore, it could be an effective substitute for egg-yolk based media due to the greater proportion of highly and progressively motile spermatozoa at thawing.

Addition of insulin-like growth factor I (IGF-I) and reduced glutathione (GSH) to cryopreserved boar semen.

The objective of this study was to evaluate the effect of adding reduced glutathione (GSH) to a boar semen freezing extender supplemented with insulin-like growth factor I (IGF-I) or anti-IGF-I. Eight ejaculates from eight boars were extended to obtain insemination doses, which were supplemented with either recombinant human IGF-I (30 ng/mL) or anti-IGF-I (60 ng/mL) shortly after extension. After 24 h of liquid storage at 17 °C, the semen was frozen with or without GSH (5 mM) in the freezing extender for a total of six treatments. Osmotic resistance and acrosome integrity was greater in fresh semen (P <  0.05) soon after adding IGF-I or the anti-IGF-I antibody. After 24 h of cooling, the supplementation with these compounds resulted in an increased (P <  0.05) percentage of sperm with relatively greater mitochondrial activity and reduced the percentage of cells with relatively greater concentrations of superoxide. After thawing, there was a reduction (P <  0.05) in the percentage and fluorescence intensity of sperm with greater quantities of superoxide and peroxide only in samples treated with GSH + IGF-I and GSH + anti-IGF-I. The addition of GSH (alone or in combination with IGF-I or anti-IGF-I), however, reduced the percentage of sperm with an intact acrosome (P < 0.05). The same effect was not observed with IGF-I or anti-IGF-I alone. In conclusion, the addition of IGF-I or anti-IGF-I improved the quality of fresh or liquid-stored semen. Using GSH in the freezing extender improved the antioxidant potential of frozen semen only in combination with IGF-I or an anti-IGF-I antibody.

Placental and uterine expression of GLUT3, but not GLUT1, is related with serum progesterone levels during the first stages of pregnancy in queens.

The present study investigated the expression of GLUT1 and GLUT3 in the uterus and placental transference zone of non-pregnant and pregnant queens throughout different pregnancy ages, using immunohistochemistry and immunoblotting techniques. Both GLUT1 and GLUT3 were expressed in both uterine glandular and luminal epithelia and myometrium in pregnant and non-pregnant queens. While endometrial endothelia showed expression of GLUT1 in both pregnant and non-pregnant queens, GLUT3 was only expressed in the pregnant counterparts. Regarding placental structures, GLUT3 was present in cytotrophoblasts, syncytiotrophoblasts and chorionic endothelia and GLUT1 showed a similar location but was absent in cytotrophoblasts. The presence of GLUT1 (55 kDa) and GLUT3 (60 kDa) was confirmed in both uterine and placental tissues through immunoblotting. When the expression of both GLUT1 and GLUT3 were analysed as a whole in the total of the pregnancy period, no significant differences in the relative content of both GLUTs were observed between pregnant and non-pregnant queens. However, when GLUTs expression was analysed in a time-period basis and related with progesterone levels, results were different. Thus, whereas the relative content of GLUT1 showed no correlation with serum progesterone levels, a significant (P < 0.05) and negative correlation was found between the relative GLUT3-content in the uterus on days 30 and 40 of pregnancy as well as in the placental transference zone on day 30 and serum progesterone levels. In summary, our results indicate that whereas GLUT1 could be considered as a basal, constant sugar intake system for the whole of pregnancy in queens, GLUT3 is specially required for optimizing glucose uptake during the first half of pregnancy in this species through a progesterone-related mechanism.

A technical assessment of the porcine ejaculated spermatozoa for a sperm-specific RNA-seq analysis.

The study of the boar sperm transcriptome by RNA-seq can provide relevant information on sperm quality and fertility and might contribute to animal breeding strategies. However, the analysis of the spermatozoa RNA is challenging as these cells harbor very low amounts of highly fragmented RNA, and the ejaculates also contain other cell types with larger amounts of non-fragmented RNA. Here, we describe a strategy for a successful boar sperm purification, RNA extraction and RNA-seq library preparation. Using these approaches our objectives were: (i) to evaluate the sperm recovery rate (SRR) after boar spermatozoa purification by density centrifugation using the non-porcine-specific commercial reagent BoviPureTM; (ii) to assess the correlation between SRR and sperm quality characteristics; (iii) to evaluate the relationship between sperm cell RNA load and sperm quality traits and (iv) to compare different library preparation kits for both total RNA-seq (SMARTer Universal Low Input RNA and TruSeq RNA Library Prep kit) and small RNA-seq (NEBNext Small RNA and TailorMix miRNA Sample Prep v2) for high-throughput sequencing. Our results show that pig SRR (~22%) is lower than in other mammalian species and that it is not significantly dependent of the sperm quality parameters analyzed in our study. Moreover, no relationship between the RNA yield per sperm cell and sperm phenotypes was found. We compared a RNA-seq library preparation kit optimized for low amounts of fragmented RNA with a standard kit designed for high amount and quality of input RNA and found that for sperm, a protocol designed to work on low-quality RNA is essential. We also compared two small RNA-seq kits and did not find substantial differences in their performance. We propose the methodological workflow described for the RNA-seq screening of the boar spermatozoa transcriptome. ABBREVIATIONS: FPKM: fragments per kilobase of transcript per million mapped reads; KRT1: keratin 1; miRNA: micro-RNA; miscRNA: miscellaneous RNA; Mt rRNA: mitochondrial ribosomal RNA; Mt tRNA: mitochondrial transference RNA; OAZ3: ornithine decarboxylase antizyme 3; ORT: osmotic resistance test; piRNA: Piwi-interacting RNA; PRM1: protamine 1; PTPRC: protein tyrosine phosphatase receptor type C; rRNA: ribosomal RNA; snoRNA: small nucleolar RNA; snRNA: small nuclear RNA; SRR: sperm recovery rate; tRNA: transfer RNA.

Supplementing Maturation Medium With Insulin Growth Factor I and Vitrification-Warming Solutions With Reduced Glutathione Enhances Survival Rates and Development Ability of in vitro Matured Vitrified-Warmed Pig Oocytes.

The present study sought to determine whether in vitro maturation (IVM) of pig oocytes in a medium supplemented with insulin growth factor-I (IGF-I) and subsequent vitrification with or without reduced glutathione (GSH) affect their quality and developmental competence, and the expression of genes involved in antioxidant, apoptotic and stress responses. In Experiment 1, cumulus-oocyte complexes were matured in the absence or presence of IGF-I (100 ng·mL-1) and then vitrified-warmed with or without 2 mM of GSH. Maturation rate was evaluated before vitrification, and oocyte viability, DNA fragmentation and relative transcript abundances of BCL-2-associated X protein (BAX), BCL2-like1 (BCL2L1), heat shock protein 70 (HSPA1A), glutathione peroxidase 1 (GPX1) and superoxide dismutase 1 (SOD1) genes were assessed in fresh and vitrified-warmed oocytes. In Experiment 2, fresh and vitrified-warmed oocytes were in vitro fertilized and their developmental competence determined. Whereas the addition of IGF-I to maturation medium had no effect on oocyte maturation, it caused an increase in the survival rate of vitrified-warmed oocytes. This effect was accompanied by a concomitant augment in the relative transcript abundance of HSPA1A and a decrease of BAX. Furthermore, the addition of GSH to vitrification-warming media increased survival rates at post-warming. Likewise, the action of GSH was concomitant with an increase in the relative abundance of GPX1 and a decrease of BAX transcript. Blastocyst rates of vitrified-warmed oocytes did not differ from their fresh counterparts when IGF-I and GSH were combined. In conclusion, supplementing maturation medium with 100 ng·mL-1 IGF-I and vitrification-warming solutions with 2 mM GSH improves the quality and cryotolerance of IVM pig oocytes, through a mechanism that involves BAX, GPX1 and HSPA1A expression.

Metabolic strategy of boar spermatozoa revealed by a metabolomic characterization.

Metabolomic characteristics in boar spermatozoa were studied using [1,2-(13)C(2)]glucose and mass isotopomer analysis. In boar spermatozoa, glycolysis was the main pathway of glucose utilization producing lactate/pyruvate, whereas no gluconeogenesis was seen. Slight glycogen synthesis through the direct pathway and some incorporation of pyruvate into the Krebs cycle also took place. Neither RNA ribose-5-phosphate nor fatty acid synthesis from glucose occurred despite the detection of pyruvate dehydrogenase activity. In contrast to the known metabolic activities in dog sperm, boar spermatozoa have low levels of energy production and biosynthetic activities suggesting two different metabolic profiles for the two different phenotypes.

Presence and function of dopamine transporter (DAT) in stallion sperm: dopamine modulates sperm motility and acrosomal integrity.

Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP(+)), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility.

The increase in phosphorylation levels of serine residues of protein HSP70 during holding time at 17°C is concomitant with a higher cryotolerance of boar spermatozoa.

Boar-sperm cryopreservation is not usually performed immediately after semen collection, but rather a holding time (HT) of 4 h-30 h at 17°C is spent before starting this procedure. Taking this into account, the aim of this study was to go further in-depth into the mechanisms underlying the improving effects of HT at 17°C on boar-sperm cryotolerance by evaluating the effects of two different HTs (3 h and 24 h) on overall boar-sperm function and survival before and after cryopreservation. Given that phospho/dephosphorylation mechanisms are of utmost importance in the overall regulation of sperm function, the phosphorylation levels of serine residues (pSer) in 30 different sperm proteins after a 3 h- or 24 h-HT period were also assessed. We found that a HT of 24 h contributed to a higher sperm resistance to freeze-thawing procedures, whereas mini-array protein analyses showed that a HT of 24 h induced a significant (P<0.05) increase in pSer (from 100.0±1.8 arbitrary units in HT 3 h to 150.2±5.1 arbitrary units in HT 24 h) of HSP70 and, to a lesser extent, in protein kinases GSK3 and total TRK and in the cell-cycle regulatory protein CDC2/CDK1. In the case of HSP70, this increase was confirmed through immunoprecipation analyses. Principal component and multiple regression analyses indicated that a component explaining a percentage of variance higher than 50% in sperm cryotolerance was significantly correlated with pSer levels in HSP70. In addition, from all the parameters evaluated before freeze-thawing, only pSer levels in HSP70 resulted to be able to predict sperm cryotolerance. In conclusion, our results suggest that boar spermatozoa modulate its function during HT, at least partially, by changes in pSer levels of proteins like HSP70, and this is related to a higher cryotolerance.

Good and bad freezability boar ejaculates differ in the integrity of nucleoprotein structure after freeze-thawing but not in ROS levels.

The main aim of the present study was to determine whether differences in the amounts of free cysteine residues in sperm nucleoproteins, which are a direct marker of the integrity of the disulfide bonds between nucleoproteins, existed between good (GFE) and poor boar freezability ejaculates (PFE) during the different steps of the freeze-thawing process. The analyzed steps were: (1) immediately before starting cryopreservation (17 °C), (2) at the end of the cooling step (5 °C), and (3) 30, and (4) 240 minutes after thawing. In addition, the present study also sought to determine whether GFE and PFE differed in the amounts of peroxides and superoxides generated during freeze-thawing as an overall measure of the boar sperm reactive oxygen species (ROS) accumulation rate. According to our results, PFE present lower resistance than GFE to cryopreservation-induced alterations of disulfide bonds between nucleoproteins, because levels of cysteine free residues were higher in PFE than in GFE at 30 and 240 minutes after thawing. On the other hand, no significant differences were observed between GFE and PFE in ROS levels during freeze-thawing. In conclusion, PFE are less resistant than GFE to cryopreservation not only in terms of sperm motility and membrane integrity, but also in the integrity of nucleoprotein structure. However, this difference between PFE and GFE in the resistance of the nucleoprotein structure to freeze-thawing is not linked with concomitant changes in ROS levels.