MicroRNA-regulated molecular mechanism underlying bovine subclinical endometritis.

An impaired uterine environment triggered by the incidence of subclinical endometritis often compromises fertility in the bovine. The uterus is a dynamic organ with tight regulation of specific genes at the transcriptional and translational levels. Herein, we hypothesised that subclinical endometritis alters the expression of uterine microRNAs (miRNAs), which may result in the dysregulation of corresponding target genes and biological pathways. To test this hypothesis, we used a genome-wide RT(2) (Exiqon, Vedbaek, Denmark) miRNA PCR array consisting of 354 miRNA primers and analysed miRNA expression in uterine cytobrush samples taken from cows with and without subclinical endometritis. The results revealed aberrant expression of 23 miRNAs in cows with subclinical endometritis compared with healthy cows. Furthermore, we designed an in vitro endometrial cell culture model challenged by lipopolysaccharide (LPS) to validate the differential regulation of miRNAs in cytobrush samples. Interestingly, we observed similar expression miRNA patterns in cytobrush samples taken from cows with or without subclinical endometritis and in vitro cultured endometrial cells challenged by LPS. To trace signalling pathways and biological functions potentially controlled by the aberrantly expressed miRNAs, we filtered high-ranking target genes from miRBase and analysed them using ingenuity pathway analysis. The gene networks, canonical pathways and biological functions strikingly converged to signalling pathways that mediate inflammatory responses, cellular proliferation, cell movement, the cell cycle and apoptosis in the bovine endometrium. In addition, expression analysis of key genes from the gene networks confirmed their presence and the potential regulation of these genes by uterine miRNAs. Furthermore, luciferase assay data substantiated the primary information from bioinformatic prediction that generated potential target genes for the dysregulated miRNAs in subclinical endometritis. Together, these data suggest the potential regulatory role of uterine miRNAs in the development and progression of bovine subclinical endometritis.

Efficiency of different selection strategies against boar taint in pigs.

The breeding scheme of a Swiss sire line was modeled to compare different target traits and information sources for selection against boar taint. The impact of selection against boar taint on production traits was assessed for different economic weights of boar taint compounds. Genetic gain and breeding costs were evaluated using ZPlan+, a software based on selection index theory, gene flow method and economic modeling. Scenario I reflected the currently practiced breeding strategy as a reference scenario without selection against boar taint. Scenario II incorporated selection against the chemical compounds of boar taint, androstenone (AND), skatole (SKA) and indole (IND) with economic weights of -2.74, -1.69 and -0.99 Euro per unit of the log transformed trait, respectively. As information sources, biopsy-based performance testing of live boars (BPT) was compared with genomic selection (GS) and a combination of both. Scenario III included selection against the subjectively assessed human nose score (HNS) of boar taint. Information sources were either station testing of full and half sibs of the selection candidate or GS against HNS of boar taint compounds. In scenario I, annual genetic gain of log-transformed AND (SKA; IND) was 0.06 (0.09; 0.02) Euro, which was because of favorable genetic correlations with lean meat percentage and meat surface. In scenario II, genetic gain increased to 0.28 (0.20; 0.09) Euro per year when conducting BPT. Compared with BPT, genetic gain was smaller with GS. A combination of BPT and GS only marginally increased annual genetic gain, whereas variable costs per selection candidate augmented from 230 Euro (BPT) to 330 Euro (GS) or 380 Euro (both). The potential of GS was found to be higher when selecting against HNS, which has a low heritability. Annual genetic gain from GS was higher than from station testing of 4 full sibs and 76 half sibs with one or two measurements. The most effective strategy to reduce HNS was selecting against chemical compounds by conducting BPT. Because of heritabilities higher than 0.45 for AND, SKA and IND and high genetic correlations to HNS, the (correlated) response in units of the trait could be increased by 62% compared with scenario III with GS and even by 79% compared with scenario III, with station testing of siblings with two measurements. Increasing the economic weights of boar taint compounds amplified negative effects on average daily gain, drip loss and intramuscular fat percentage.

Investigation on association and expression of ESR2 as a candidate gene for boar sperm quality and fertility.

ESR2 is involved in oestrogen-related apoptosis in cell cycle spermatogenesis but their effects have not yet confirmed in pig. Therefore, this study was aimed to investigate the association of ESR2 polymorphism with sperm quality and boar fertility traits and to analyse the ESR2 mRNA and protein expressions in boar reproductive tissues. DNA samples from 203 Pietrain (PI) and 100 Pietrain × Hampshire (PIHA) pigs with records of sperm quality [sperm concentration (SCON), motility (MOT), semen volume (VOL), plasma droplet rate (PDR) and abnormal spermatozoa rate (ASR)] and fertility [non-return rate (NRR) and number of piglet born alive (NBA)] traits were available. A SNP in coding region of ESR2 g.35547A>G in exon 5 was associated with MOT and PDR in the PI and with SCON, VOL, MOT and PDR in PIHA population. For mRNA and protein expression study, a total of six boars were divided into two groups with group I (G-I) and group II (G-II) where G-I characterized for relatively a better sperm quality according to the mean of two groups. mRNA expression was higher in brain and testis than that in all parts of epididymis. Both qRT-PCR and western blot analysis revealed that the ESR2 gene expression and protein expression were significantly higher in testis collected from G-II compared with that of G-I boars. Moreover, ESR2 protein localization in germ cell, Leydig and Sertoli cells, epithelial cells and spermatozoa was remarkable, which indicated the important role of ESR2 in spermatogenesis process. These results might shed new light on the roles of ESR2 in spermatogenesis as candidate for boar fertility, but still the lack of association across populations should be considered.

Bovine blastocysts with developmental competence to term share similar expression of developmentally important genes although derived from different culture environments.

This study was conducted to investigate the gene expression profile of in vivo-derived bovine embryo biopsies based on pregnancy outcomes after transferring to recipients. For this, biopsies of 30-40% embryos were taken from grade I blastocysts (International Embryo Transfer Society Manual) and the remaining 60-70% of the intact embryos were transferred to recipients. Frozen biopsies were pooled into three distinct groups based on the pregnancy outcome after transferring the corresponding parts, namely those resulting in no pregnancy (NP), pregnancy loss (PL), and calf delivery (CD). Array analysis revealed a total of 41 and 43 genes to be differentially expressed between biopsies derived from blastocysts resulting in NP versus CD and PL versus CD respectively. Genes regulating placental development and embryo maternal interaction (PLAC8) were found to be upregulated in embryo biopsies that ended up with CD. Embryo biopsies that failed to induce pregnancy were enriched with mitochondrial transcripts (Fl405) and stress-related genes (HSPD1). Overall, gene expression profiles of blastocysts resulting in NP and CD shared similar expression profiles with respect to genes playing significant roles in preimplantation development of embryo. Finally, comparing the transcript signatures of in vivo- and in vitro-derived embryos with developmental competence to term revealed a similarity in the relative abundance of 18 genes. Therefore, we were able to present a genetic signature associated with term developmental competence independent of the environmental origin of the transferred blastocysts.

Candidate gene markers for sperm quality and fertility of boar.

Candidate genes gonadotropin releasing hormone receptor (GNRHR), prolactin (PRL), prolactin receptor (PRLR), follicle-stimulating hormone beta (FSHB), luteinizing hormone beta (LHB), follistatin (FST), inhibin alpha (INHA), inhibin beta A (INHBA) and inhibin beta B (INHBB) were investigated for their association with sperm quality traits of sperm concentration (SCON), motility (MOT), semen volume per ejaculate (VOL), plasma droplets rate (PDR), abnormal sperm rate (ASR) and fertility traits of non return rate (NRR) and number of piglets born alive (NBA). The experimental material included 356 boars of Pietrain (PI) and Pietrain x Hampshire (PI x HA). Analysis of variance revealed significant association of GNRHR with MOT (P = 0.0161), PDR (P = 0.0048) and ASR (P = 0.0201), INHBA was found to have significant effects on PDR (P = 0.0318) and ASR (P = 0.0067), INHBB was significant (P = 0.0360) for SCON trait. FSHB, FST, INHA, PRL, PRLR and LHB had no significant effects on any trait in this experiment.