Protein profiling of testicular tissue from boars with different levels of hyperactive sperm motility

Hyperactive sperm motility is important for successful fertilization. In the present study, a proteome profiling approach was performed to identify the differences between Landrace boars with different levels of hyperactive sperm motility in liquid extended semen. Two contrasts were studied: (i) high versus low levels of sperm hyperactivity at semen collection day and (ii) high versus low change in levels of sperm hyperactivity after 96 h semen storage. Testicular samples were analyzed on a Q Exactive mass spectrometer and more than 6000 proteins were identified in the 13 samples. The most significant differentially expressed proteins were mediator complex subunit 28 (MED28), cell division cycle 37 like 1 (CDC37L1), ubiquitin specific peptidase 10 (USP10), zinc finger FYVE-type containing 26 (ZFYVE26), protein kinase C delta (PRKCD), actinin alpha 4 (ACTN4), N(alpha)-acetyltransferase 30 (NAA30), C1q domain-containing (LOC110258309) and uncharacterized LOC100512926. Of the differentially expressed proteins, 11 have previously been identified as differentially expressed at the corresponding mRNA transcript level using the same samples and contrasts. These include sphingosine kinase 1 isoform 2 (SPHK1), serine and arginine rich splicing factor 1 (SRSF1), and tubulin gamma-1 (TUBG1) which are involved in the acrosome reaction and sperm motility. A mass spectrometry approach was applied to investigate the protein profiles of boars with different levels of hyperactive sperm motility. This study identified several proteins previously shown to be involved in sperm motility and quality, but also proteins with no known function for sperm motility. Candidates that are differentially expressed on both mRNA and protein levels are especially relevant as biological markers of semen quality.

Transcriptome profiling of porcine testis tissue reveals genes related to sperm hyperactive motility

BACKGROUND

Sperm hyperactive motility has previously been shown to influence litter size in pigs, but little is known about the underlying biological mechanisms. The aim of this study was to use RNA sequencing to investigate gene expression differences in testis tissue from Landrace and Duroc boars with high and low levels of sperm hyperactive motility. Boars with divergent phenotypes were selected based on their sperm hyperactivity values at the day of ejaculation (day 0) (contrasts (i) and (ii) for Landrace and Duroc, respectively) and on their change in hyperactivity between day 0 and after 96 h liquid storage at 18 °C (contrast (iii)).

RESULTS

RNA sequencing was used to measure gene expression in testis. In Landrace boars, 3219 genes were differentially expressed for contrast (i), whereas 102 genes were differentially expressed for contrast (iii). Forty-one differentially expressed genes were identified in both contrasts, suggesting a functional role of these genes in hyperactivity regardless of storage. Zinc finger DNLZ was the most up-regulated gene in contrasts (i) and (iii), whereas the most significant differentially expressed gene for the two contrasts were ADP ribosylation factor ARFGAP1 and solute carrier SLC40A1, respectively. For Duroc (contrast (ii)), the clustering of boars based on their gene expression data did not reflect their difference in sperm hyperactivity phenotypes. No results were therefore obtained for this breed. A case-control analysis of variants identified in the Landrace RNA sequencing data showed that SNPs in NEU3, CHRDL2 and HMCN1 might be important for sperm hyperactivity.

CONCLUSIONS

Differentially expressed genes were identified in Landrace boars with high and low levels of sperm hyperactivity at the day of ejaculate collection and high and low change in hyperactivity after 96 h of sperm storage. The results point towards important candidate genes, biochemical pathways and sequence variants underlying sperm hyperactivity in pigs.

Association between single-nucleotide polymorphisms within candidate genes and fertility in Landrace and Duroc pigs

Finding effective predictors of traits related to boar fertility is essential for increasing the efficiency of artificial insemination systems in pig breeding. The objective of this study was to find associations between single-nucleotide polymorphisms (SNPs) within candidate genes and fertility in the breeds Landrace and Duroc. Animals with breeding values for total number of piglets born, were re-sequenced for exonic regions of 14 candidate genes related to male and female fertility using samples from 16 Landrace boars and 16 Duroc boars (four with high and four with low breeding value of total number of piglets born for each breed for male fertility, and the same for female fertility) to detect genetic variants. Genotyping for the detected SNPs was done in 619 Landrace boars and 513 Duroc boars. Two SNPs in BMPR1 and one SNP in COX-2 were found significantly associated with the total number of piglets born in Landrace. In Duroc, two SNPs in PLC_z, one SNP in VWF and one SNP in ZP3 were found significantly associated with total number of piglets born. These SNPs explained between 0.27% and 1.18% of the genetic variance. These effects are too low for being used directly for selection purposes but can be of interest in SNP-panels used for genomic selection.

Relationship between sperm motility characteristics and ATP concentrations, and association with fertility in two different pig breeds

Boar fertility has a major impact on overall pig reproductive efficiency. Using accurate and objective in vitro sperm variables for predicting in vivo fertility from a single ejaculate, however, is challenging. Motility is the most widely used indicator of sperm quality, and a computer assisted sperm analysis (CASA) system is now available for objective assessment of sperm motility characteristics. In this study sperm motility characteristics and semen ATP concentrations were investigated and the effect of both were evaluated on total number of piglets born (TNB) when Norwegian Landrace (NL) and Norwegian Duroc (ND) boar semen was used for AI. In addition, breed differences for semen storage capacity were investigated. The results from CASA analysis indicated there were differences between NL and ND sperm motility variables. The percentage of motile sperm cells decreased in both NL (P = 0.01) and ND (P < 0.0001) during storage. A large proportion of sperm cells with a hyperactive motility pattern were detected in ND semen on the day of collection, with no significant changes as a result of storage. Inconsistent with this finding, there was greater degree of hyper-activation in sperm motility pattern for NL because of semen storage. There was a significant decrease in semen ATP concentration during storage (P < 0.0001) in both breeds. The linearity of sperm movement at the day of collection and the wobble after storage influenced TNB in NL, while the percentage of motile cells, curvilinear velocity and lateral head amplitude on the day of semen collection and linearity after storage influenced TNB in ND.

RNA sequencing reveals candidate genes and polymorphisms related to sperm DNA integrity in testis tissue from boars

Background

Sperm DNA is protected against fragmentation by a high degree of chromatin packaging. It has been demonstrated that proper chromatin packaging is important for boar fertility outcome. However, little is known about the molecular mechanisms underlying differences in sperm DNA fragmentation. Knowledge of sequence variation influencing this sperm parameter could be beneficial in selecting the best artificial insemination (AI) boars for commercial production. The aim of this study was to identify genes differentially expressed in testis tissue of Norwegian Landrace and Duroc boars, with high and low sperm DNA fragmentation index (DFI), using transcriptome sequencing.

Results

Altogether, 308 and 374 genes were found to display significant differences in expression level between high and low DFI in Landrace and Duroc boars, respectively. Of these genes, 71 were differentially expressed in both breeds. Gene ontology analysis revealed that significant terms in common for the two breeds included extracellular matrix, extracellular region and calcium ion binding. Moreover, different metabolic processes were enriched in Landrace and Duroc, whereas immune response terms were common in Landrace only. Variant detection identified putative polymorphisms in some of the differentially expressed genes. Validation showed that predicted high impact variants in RAMP2, GIMAP6 and three uncharacterized genes are particularly interesting for sperm DNA fragmentation in boars.

Conclusions

We identified differentially expressed genes between groups of boars with high and low sperm DFI, and functional annotation of these genes point towards important biochemical pathways. Moreover, variant detection identified putative polymorphisms in the differentially expressed genes. Our results provide valuable insights into the molecular network underlying DFI in pigs.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1279-x) contains supplementary material, which is available to authorized users.

Exposure to the three structurally different PCB congeners (PCB 118, 153, and 126) results in decreased protein expression and altered steroidogenesis in the human adrenocortical carcinoma cell line H295R

Polychlorinated biphenyls (PCB), synthetic, persistent organic pollutants (POP), are detected ubiquitously, in water, soil, air, and sediments, as well as in animals and humans. PCB are associated with range of adverse health effects, such as interference with the immune system and nervous system, reproductive abnormalities, fetotoxicity, carcinogenicity, and endocrine disruption. Our objective was to determine the effects of three structurally different PCB congeners, PCB118, PCB 126, and PCB 153, each at two concentrations, on the steroidogenic capacity and proteome of human adrenocortical carcinoma cell line cultures (H295R) . After 48 h of exposure, cell viability was monitored and estradiol, testosterone, cortisol and progesterone secretion measured to quantify steroidogenic capacity of the cells. Two-dimensional (2D) gel-based proteomics was used to screen for proteome alterations in H295R cells in response to the PCB. Exposure to PCB 118 increased estradiol and cortisol secretion, while exposure to PCB 153 elevated estradiol secretion. PCB 126 was the most potent congener, increasing estradiol, cortisol, and progesterone secretion in exposed H295R cells. Seventy-three of the 711 spots analyzed showed a significant difference in normalized spot volumes between controls (vehicle only) and at least one exposure group. Fourteen of these protein spots were identified by liquid chromatography with mass spectroscopy (LC-MS/MS). Exposure to three PCB congeners with different chemical structure perturbed steroidogenesis and protein expression in the H295R in vitro model. This study represents an initial analysis of the effects on proteins and hormones in the H295R cell model, and additional studies are required in order to obtain a more complete understanding of the pathways disturbed by PCB congeners in H295R cells. Overall, alterations in protein regulation and steroid hormone synthesis suggest that exposure to PCB disturbs several cellular processes, including protein synthesis, stress response, and apoptosis.