The Experts below are selected from a list of 6573 Experts worldwide ranked by ideXlab platform
Ottmar Distl - One of the best experts on this subject based on the ideXlab platform.
-
Effects of inbreeding and other systematic effects on fertility of Black Forest Draught horses in Germany
Acta Veterinaria Scandinavica, 2017Co-Authors: Maarit Müller-unterberg, Sandra Wallmann, Ottmar DistlAbstract:Background The Black Forest Draught horse (BFDH) is an endangered German coldblood breed with its origin in the area of the Black Forest in South Germany. In this retrospective study, the influence of the inbreeding coefficient on foaling rates was investigated using records from ten breeding seasons. Due to the small population size of BFDH, the level of inbreeding is increasing and may have an effect on foaling rates.The data of the present study included all coverings reported for 1024 BFDH mares in the years 2001–2009. These mares were covered by 32 BFDH Stallions from the State Stud Marbach. Data from 4534 estrus cycles was used to calculate per cycle foaling rate (CFR). Pedigree data contained all studbook data up to the foundation of the breed as early as 1836. The level of inbreeding of the mare, stallion and expected foal along with other systematic effects on CFR were analysed using a generalized linear mixed model approach. Stallion was employed as a random effect. Systematic fixed effects were month of mating, mating type, age of the mare and stallion, reproductive status of the mare and stallion line of the mare. Inbreeding coefficients of the stallion, mare and expected foal were modelled as linear covariates. Results The average CFR was 40.9%. The mean inbreeding coefficients of the mares, Stallions and expected foals were 7.46, 7.70 and 9.66%. Mating type, age of the mare, reproductive status of the mare and stallion line of the mare had a significant effect. Conclusions The results showed that the mating type, stallion line of the mare, sire, age and reproductive status of the mare exerted the largest influences on CFR in BFDH. Inbreeding coefficients of the stallion, mare and expected foal were not significantly related with CFR.
-
relationships among stallion fertility and semen traits using estimated breeding values of german warmblood Stallions
Theriogenology, 2017Co-Authors: Maren Gottschalk, H Sieme, G Martinsson, Ottmar DistlAbstract:Abstract A high quality of stallion semen is of particular importance for maximum reproductive efficiency. In the present study, we estimated the relationships among estimated breeding values (EBVs) of semen traits and EBVs for the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) for 100 German Warmblood Stallions using correlation and general linear model analyses. The most highly correlated sperm quality trait was total number of progressively motile sperm ( r = 0.36). EBV-PAT was considered in three classes with Stallions 1 SD below ( 120) the population mean of 100. The general linear model analysis showed significant effects for EBVs of all semen traits. EBVs of sperm quality traits greater than 100 to 110 were indicative for EBV-PAT greater than 120. Recommendations for breeding soundness examinations on the basis of the assessments of sperm quality traits and estimation of breeding values seem to be an option to support breeders to improve stallion fertility in the present and future stallion generation.
-
screening of whole genome sequences identified high impact variants for stallion fertility
BMC Genomics, 2016Co-Authors: Rahel Schrimpf, Maren Gottschalk, Julia Metzger, H Sieme, G Martinsson, Ottmar DistlAbstract:Background Stallion fertility is an economically important trait due to the increase of artificial insemination in horses. The availability of whole genome sequence data facilitates identification of rare high-impact variants contributing to stallion fertility. The aim of our study was to genotype rare high-impact variants retrieved from next-generation sequencing (NGS)-data of 11 horses in order to unravel harmful genetic variants in large samples of Stallions.
-
Analysis of breed effects on semen traits in light horse, warmblood, and draught horse breeds
Theriogenology, 2015Co-Authors: Maren Gottschalk, H Sieme, G Martinsson, Ottmar DistlAbstract:In the present study, systematic effects on semen quality traits were investigated in 381 Stallions representing 22 breeds. All Stallions were used for AI either at the Lower Saxon National Stud Celle or the North Rhine-Westphalian National Stud Warendorf. A total of 71,078 fresh semen reports of the years 2001 to 2014 were edited for analysis of gel-free volume, sperm concentration, total number of sperm, progressive motility, and total number of progressively motile sperm. Breed differences were studied for warmblood and light horse breeds of both national studs (model I) and for warmblood breeds and the draught horse breed Rhenish German Coldblood from the North Rhine-Westphalian National stud (model II) using mixed model procedures. The fixed effects of age class, year, and month of semen collection had significant influences on all semen traits in both analyses. A significant influence of the horse breed was found for all semen traits but gel-free volume in both statistical models. Comparing warmblood and light horse Stallions of both national studs, we observed highest sperm concentrations, total numbers of sperm, and total numbers of progressively motile sperm in Anglo-Arabian Stallions. The draught horse breed Rhenish German Coldblood had the highest least squares means for gel-free volume, whereas all other investigated semen traits were significantly lower in this breed compared to the warmblood Stallions under study. The variance components among Stallions within breeds were significant for all semen traits and accounted for 40% to 59% of the total variance. The between-breed-variance among Stallions was not significant underlining the similar size of the random stallion effect in each of the horse breeds analyzed here. In conclusion, breed and stallion are accounting for a significant proportion of the variation in semen quality.
-
genome wide association study identifies phospholipase c zeta 1 plcz1 as a stallion fertility locus in hanoverian warmblood horses
PLOS ONE, 2014Co-Authors: Rahel Schrimpf, H Sieme, G Martinsson, Claudia Dierks, Ottmar DistlAbstract:A consistently high level of stallion fertility plays an economically important role in modern horse breeding. We performed a genome-wide association study for estimated breeding values of the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) in Hanoverian Stallions. A total of 228 Hanoverian Stallions were genotyped using the Equine SNP50 Beadchip. The most significant association was found on horse chromosome 6 for a single nucleotide polymorphism (SNP) within phospholipase C zeta 1 (PLCz1). In the close neighbourhood to PLCz1 is located CAPZA3 (capping protein (actin filament) muscle Z-line, alpha 3). The gene PLCz1 encodes a protein essential for spermatogenesis and oocyte activation through sperm induced Ca2+-oscillation during fertilization. We derived equine gene models for PLCz1 and CAPZA3 based on cDNA and genomic DNA sequences. The equine PLCz1 had four different transcripts of which two contained a premature termination codon. Sequencing all exons and their flanking sequences using genomic DNA samples from 19 Hanoverian Stallions revealed 47 polymorphisms within PLCz1 and one SNP within CAPZA3. Validation of these 48 polymorphisms in 237 Hanoverian Stallions identified three intronic SNPs within PLCz1 as significantly associated with EBV-PAT. Bioinformatic analysis suggested regulatory effects for these SNPs via transcription factor binding sites or microRNAs. In conclusion, non-coding polymorphisms within PLCz1 were identified as conferring stallion fertility and PLCz1 as candidate locus for male fertility in Hanoverian warmblood. CAPZA3 could be eliminated as candidate gene for fertility in Hanoverian Stallions.
Rahel Schrimpf - One of the best experts on this subject based on the ideXlab platform.
-
screening of whole genome sequences identified high impact variants for stallion fertility
BMC Genomics, 2016Co-Authors: Rahel Schrimpf, Maren Gottschalk, Julia Metzger, H Sieme, G Martinsson, Ottmar DistlAbstract:Background Stallion fertility is an economically important trait due to the increase of artificial insemination in horses. The availability of whole genome sequence data facilitates identification of rare high-impact variants contributing to stallion fertility. The aim of our study was to genotype rare high-impact variants retrieved from next-generation sequencing (NGS)-data of 11 horses in order to unravel harmful genetic variants in large samples of Stallions.
-
genome wide association study identifies phospholipase c zeta 1 plcz1 as a stallion fertility locus in hanoverian warmblood horses
PLOS ONE, 2014Co-Authors: Rahel Schrimpf, H Sieme, G Martinsson, Claudia Dierks, Ottmar DistlAbstract:A consistently high level of stallion fertility plays an economically important role in modern horse breeding. We performed a genome-wide association study for estimated breeding values of the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) in Hanoverian Stallions. A total of 228 Hanoverian Stallions were genotyped using the Equine SNP50 Beadchip. The most significant association was found on horse chromosome 6 for a single nucleotide polymorphism (SNP) within phospholipase C zeta 1 (PLCz1). In the close neighbourhood to PLCz1 is located CAPZA3 (capping protein (actin filament) muscle Z-line, alpha 3). The gene PLCz1 encodes a protein essential for spermatogenesis and oocyte activation through sperm induced Ca2+-oscillation during fertilization. We derived equine gene models for PLCz1 and CAPZA3 based on cDNA and genomic DNA sequences. The equine PLCz1 had four different transcripts of which two contained a premature termination codon. Sequencing all exons and their flanking sequences using genomic DNA samples from 19 Hanoverian Stallions revealed 47 polymorphisms within PLCz1 and one SNP within CAPZA3. Validation of these 48 polymorphisms in 237 Hanoverian Stallions identified three intronic SNPs within PLCz1 as significantly associated with EBV-PAT. Bioinformatic analysis suggested regulatory effects for these SNPs via transcription factor binding sites or microRNAs. In conclusion, non-coding polymorphisms within PLCz1 were identified as conferring stallion fertility and PLCz1 as candidate locus for male fertility in Hanoverian warmblood. CAPZA3 could be eliminated as candidate gene for fertility in Hanoverian Stallions.
-
genome wide association study identifies phospholipase c zeta 1 plcz1 as a stallion fertility locus in hanoverian warmblood horses
PLOS ONE, 2014Co-Authors: Rahel Schrimpf, H Sieme, G Martinsson, Claudia Dierks, Ottmar DistlAbstract:A consistently high level of stallion fertility plays an economically important role in modern horse breeding. We performed a genome-wide association study for estimated breeding values of the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) in Hanoverian Stallions. A total of 228 Hanoverian Stallions were genotyped using the Equine SNP50 Beadchip. The most significant association was found on horse chromosome 6 for a single nucleotide polymorphism (SNP) within phospholipase C zeta 1 (PLCz1). In the close neighbourhood to PLCz1 is located CAPZA3 (capping protein (actin filament) muscle Z-line, alpha 3). The gene PLCz1 encodes a protein essential for spermatogenesis and oocyte activation through sperm induced Ca2+-oscillation during fertilization. We derived equine gene models for PLCz1 and CAPZA3 based on cDNA and genomic DNA sequences. The equine PLCz1 had four different transcripts of which two contained a premature termination codon. Sequencing all exons and their flanking sequences using genomic DNA samples from 19 Hanoverian Stallions revealed 47 polymorphisms within PLCz1 and one SNP within CAPZA3. Validation of these 48 polymorphisms in 237 Hanoverian Stallions identified three intronic SNPs within PLCz1 as significantly associated with EBV-PAT. Bioinformatic analysis suggested regulatory effects for these SNPs via transcription factor binding sites or microRNAs. In conclusion, non-coding polymorphisms within PLCz1 were identified as conferring stallion fertility and PLCz1 as candidate locus for male fertility in Hanoverian warmblood. CAPZA3 could be eliminated as candidate gene for fertility in Hanoverian Stallions.
H Sieme - One of the best experts on this subject based on the ideXlab platform.
-
Cycle-specific female preferences for visual and non-visual cues in the horse (Equus caballus)
2018Co-Authors: Dominik Burger, H Sieme, Claus Wedekind, Charles Meuwly, Selina Thomas, Michael Oberthür, Sabine Meinecke-tillmannAbstract:Although female preferences are well studied in many mammals, the possible effects of the oestrous cycle are not yet sufficiently understood. Here we investigate female preferences for visual and non-visual male traits relative to the periodically cycling of sexual proceptivity (oestrus) and inactivity (dioestrus), respectively, in the polygynous horse (Equus caballus). We individually exposed mares to Stallions in four experimental situations: (i) mares in oestrus and visual contact to Stallions allowed, (ii) mares in oestrus, with blinds (wooden partitions preventing visual contact but allowing for acoustic and olfactory communication), (iii) mares in dioestrus, no blinds, and (iv) mares in dioestrus, with blinds. Contact times of the mares with each stallion, defined as the cumulative amount of time a mare was in the vicinity of an individual stallion and actively searching contact, were used to rank Stallions according to each mare’s preferences. We found that preferences based on visual traits differed significantly from preferences based on non-visual traits in dioestrous mares. The mares then showed a preference for older and larger males, but only if visual cues were available. In contrast, oestrous mares showed consistent preferences with or without blinds, i.e. their preferences were mainly based on non-visual traits and could not be predicted by male age or size. Stallions who were generally preferred displayed a high libido that may have positively influenced female interest or may have been a consequence of it. We conclude that the oestrous cycle has a significant influence on female preferences for visual and non-visual male traits in the horse.
-
relationships among stallion fertility and semen traits using estimated breeding values of german warmblood Stallions
Theriogenology, 2017Co-Authors: Maren Gottschalk, H Sieme, G Martinsson, Ottmar DistlAbstract:Abstract A high quality of stallion semen is of particular importance for maximum reproductive efficiency. In the present study, we estimated the relationships among estimated breeding values (EBVs) of semen traits and EBVs for the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) for 100 German Warmblood Stallions using correlation and general linear model analyses. The most highly correlated sperm quality trait was total number of progressively motile sperm ( r = 0.36). EBV-PAT was considered in three classes with Stallions 1 SD below ( 120) the population mean of 100. The general linear model analysis showed significant effects for EBVs of all semen traits. EBVs of sperm quality traits greater than 100 to 110 were indicative for EBV-PAT greater than 120. Recommendations for breeding soundness examinations on the basis of the assessments of sperm quality traits and estimation of breeding values seem to be an option to support breeders to improve stallion fertility in the present and future stallion generation.
-
screening of whole genome sequences identified high impact variants for stallion fertility
BMC Genomics, 2016Co-Authors: Rahel Schrimpf, Maren Gottschalk, Julia Metzger, H Sieme, G Martinsson, Ottmar DistlAbstract:Background Stallion fertility is an economically important trait due to the increase of artificial insemination in horses. The availability of whole genome sequence data facilitates identification of rare high-impact variants contributing to stallion fertility. The aim of our study was to genotype rare high-impact variants retrieved from next-generation sequencing (NGS)-data of 11 horses in order to unravel harmful genetic variants in large samples of Stallions.
-
Analysis of breed effects on semen traits in light horse, warmblood, and draught horse breeds
Theriogenology, 2015Co-Authors: Maren Gottschalk, H Sieme, G Martinsson, Ottmar DistlAbstract:In the present study, systematic effects on semen quality traits were investigated in 381 Stallions representing 22 breeds. All Stallions were used for AI either at the Lower Saxon National Stud Celle or the North Rhine-Westphalian National Stud Warendorf. A total of 71,078 fresh semen reports of the years 2001 to 2014 were edited for analysis of gel-free volume, sperm concentration, total number of sperm, progressive motility, and total number of progressively motile sperm. Breed differences were studied for warmblood and light horse breeds of both national studs (model I) and for warmblood breeds and the draught horse breed Rhenish German Coldblood from the North Rhine-Westphalian National stud (model II) using mixed model procedures. The fixed effects of age class, year, and month of semen collection had significant influences on all semen traits in both analyses. A significant influence of the horse breed was found for all semen traits but gel-free volume in both statistical models. Comparing warmblood and light horse Stallions of both national studs, we observed highest sperm concentrations, total numbers of sperm, and total numbers of progressively motile sperm in Anglo-Arabian Stallions. The draught horse breed Rhenish German Coldblood had the highest least squares means for gel-free volume, whereas all other investigated semen traits were significantly lower in this breed compared to the warmblood Stallions under study. The variance components among Stallions within breeds were significant for all semen traits and accounted for 40% to 59% of the total variance. The between-breed-variance among Stallions was not significant underlining the similar size of the random stallion effect in each of the horse breeds analyzed here. In conclusion, breed and stallion are accounting for a significant proportion of the variation in semen quality.
-
genome wide association study identifies phospholipase c zeta 1 plcz1 as a stallion fertility locus in hanoverian warmblood horses
PLOS ONE, 2014Co-Authors: Rahel Schrimpf, H Sieme, G Martinsson, Claudia Dierks, Ottmar DistlAbstract:A consistently high level of stallion fertility plays an economically important role in modern horse breeding. We performed a genome-wide association study for estimated breeding values of the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) in Hanoverian Stallions. A total of 228 Hanoverian Stallions were genotyped using the Equine SNP50 Beadchip. The most significant association was found on horse chromosome 6 for a single nucleotide polymorphism (SNP) within phospholipase C zeta 1 (PLCz1). In the close neighbourhood to PLCz1 is located CAPZA3 (capping protein (actin filament) muscle Z-line, alpha 3). The gene PLCz1 encodes a protein essential for spermatogenesis and oocyte activation through sperm induced Ca2+-oscillation during fertilization. We derived equine gene models for PLCz1 and CAPZA3 based on cDNA and genomic DNA sequences. The equine PLCz1 had four different transcripts of which two contained a premature termination codon. Sequencing all exons and their flanking sequences using genomic DNA samples from 19 Hanoverian Stallions revealed 47 polymorphisms within PLCz1 and one SNP within CAPZA3. Validation of these 48 polymorphisms in 237 Hanoverian Stallions identified three intronic SNPs within PLCz1 as significantly associated with EBV-PAT. Bioinformatic analysis suggested regulatory effects for these SNPs via transcription factor binding sites or microRNAs. In conclusion, non-coding polymorphisms within PLCz1 were identified as conferring stallion fertility and PLCz1 as candidate locus for male fertility in Hanoverian warmblood. CAPZA3 could be eliminated as candidate gene for fertility in Hanoverian Stallions.
G Martinsson - One of the best experts on this subject based on the ideXlab platform.
-
relationships among stallion fertility and semen traits using estimated breeding values of german warmblood Stallions
Theriogenology, 2017Co-Authors: Maren Gottschalk, H Sieme, G Martinsson, Ottmar DistlAbstract:Abstract A high quality of stallion semen is of particular importance for maximum reproductive efficiency. In the present study, we estimated the relationships among estimated breeding values (EBVs) of semen traits and EBVs for the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) for 100 German Warmblood Stallions using correlation and general linear model analyses. The most highly correlated sperm quality trait was total number of progressively motile sperm ( r = 0.36). EBV-PAT was considered in three classes with Stallions 1 SD below ( 120) the population mean of 100. The general linear model analysis showed significant effects for EBVs of all semen traits. EBVs of sperm quality traits greater than 100 to 110 were indicative for EBV-PAT greater than 120. Recommendations for breeding soundness examinations on the basis of the assessments of sperm quality traits and estimation of breeding values seem to be an option to support breeders to improve stallion fertility in the present and future stallion generation.
-
screening of whole genome sequences identified high impact variants for stallion fertility
BMC Genomics, 2016Co-Authors: Rahel Schrimpf, Maren Gottschalk, Julia Metzger, H Sieme, G Martinsson, Ottmar DistlAbstract:Background Stallion fertility is an economically important trait due to the increase of artificial insemination in horses. The availability of whole genome sequence data facilitates identification of rare high-impact variants contributing to stallion fertility. The aim of our study was to genotype rare high-impact variants retrieved from next-generation sequencing (NGS)-data of 11 horses in order to unravel harmful genetic variants in large samples of Stallions.
-
Analysis of breed effects on semen traits in light horse, warmblood, and draught horse breeds
Theriogenology, 2015Co-Authors: Maren Gottschalk, H Sieme, G Martinsson, Ottmar DistlAbstract:In the present study, systematic effects on semen quality traits were investigated in 381 Stallions representing 22 breeds. All Stallions were used for AI either at the Lower Saxon National Stud Celle or the North Rhine-Westphalian National Stud Warendorf. A total of 71,078 fresh semen reports of the years 2001 to 2014 were edited for analysis of gel-free volume, sperm concentration, total number of sperm, progressive motility, and total number of progressively motile sperm. Breed differences were studied for warmblood and light horse breeds of both national studs (model I) and for warmblood breeds and the draught horse breed Rhenish German Coldblood from the North Rhine-Westphalian National stud (model II) using mixed model procedures. The fixed effects of age class, year, and month of semen collection had significant influences on all semen traits in both analyses. A significant influence of the horse breed was found for all semen traits but gel-free volume in both statistical models. Comparing warmblood and light horse Stallions of both national studs, we observed highest sperm concentrations, total numbers of sperm, and total numbers of progressively motile sperm in Anglo-Arabian Stallions. The draught horse breed Rhenish German Coldblood had the highest least squares means for gel-free volume, whereas all other investigated semen traits were significantly lower in this breed compared to the warmblood Stallions under study. The variance components among Stallions within breeds were significant for all semen traits and accounted for 40% to 59% of the total variance. The between-breed-variance among Stallions was not significant underlining the similar size of the random stallion effect in each of the horse breeds analyzed here. In conclusion, breed and stallion are accounting for a significant proportion of the variation in semen quality.
-
genome wide association study identifies phospholipase c zeta 1 plcz1 as a stallion fertility locus in hanoverian warmblood horses
PLOS ONE, 2014Co-Authors: Rahel Schrimpf, H Sieme, G Martinsson, Claudia Dierks, Ottmar DistlAbstract:A consistently high level of stallion fertility plays an economically important role in modern horse breeding. We performed a genome-wide association study for estimated breeding values of the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) in Hanoverian Stallions. A total of 228 Hanoverian Stallions were genotyped using the Equine SNP50 Beadchip. The most significant association was found on horse chromosome 6 for a single nucleotide polymorphism (SNP) within phospholipase C zeta 1 (PLCz1). In the close neighbourhood to PLCz1 is located CAPZA3 (capping protein (actin filament) muscle Z-line, alpha 3). The gene PLCz1 encodes a protein essential for spermatogenesis and oocyte activation through sperm induced Ca2+-oscillation during fertilization. We derived equine gene models for PLCz1 and CAPZA3 based on cDNA and genomic DNA sequences. The equine PLCz1 had four different transcripts of which two contained a premature termination codon. Sequencing all exons and their flanking sequences using genomic DNA samples from 19 Hanoverian Stallions revealed 47 polymorphisms within PLCz1 and one SNP within CAPZA3. Validation of these 48 polymorphisms in 237 Hanoverian Stallions identified three intronic SNPs within PLCz1 as significantly associated with EBV-PAT. Bioinformatic analysis suggested regulatory effects for these SNPs via transcription factor binding sites or microRNAs. In conclusion, non-coding polymorphisms within PLCz1 were identified as conferring stallion fertility and PLCz1 as candidate locus for male fertility in Hanoverian warmblood. CAPZA3 could be eliminated as candidate gene for fertility in Hanoverian Stallions.
-
genome wide association study identifies phospholipase c zeta 1 plcz1 as a stallion fertility locus in hanoverian warmblood horses
PLOS ONE, 2014Co-Authors: Rahel Schrimpf, H Sieme, G Martinsson, Claudia Dierks, Ottmar DistlAbstract:A consistently high level of stallion fertility plays an economically important role in modern horse breeding. We performed a genome-wide association study for estimated breeding values of the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) in Hanoverian Stallions. A total of 228 Hanoverian Stallions were genotyped using the Equine SNP50 Beadchip. The most significant association was found on horse chromosome 6 for a single nucleotide polymorphism (SNP) within phospholipase C zeta 1 (PLCz1). In the close neighbourhood to PLCz1 is located CAPZA3 (capping protein (actin filament) muscle Z-line, alpha 3). The gene PLCz1 encodes a protein essential for spermatogenesis and oocyte activation through sperm induced Ca2+-oscillation during fertilization. We derived equine gene models for PLCz1 and CAPZA3 based on cDNA and genomic DNA sequences. The equine PLCz1 had four different transcripts of which two contained a premature termination codon. Sequencing all exons and their flanking sequences using genomic DNA samples from 19 Hanoverian Stallions revealed 47 polymorphisms within PLCz1 and one SNP within CAPZA3. Validation of these 48 polymorphisms in 237 Hanoverian Stallions identified three intronic SNPs within PLCz1 as significantly associated with EBV-PAT. Bioinformatic analysis suggested regulatory effects for these SNPs via transcription factor binding sites or microRNAs. In conclusion, non-coding polymorphisms within PLCz1 were identified as conferring stallion fertility and PLCz1 as candidate locus for male fertility in Hanoverian warmblood. CAPZA3 could be eliminated as candidate gene for fertility in Hanoverian Stallions.
E L Squires - One of the best experts on this subject based on the ideXlab platform.
-
intrahost selection pressure drives equine arteritis virus evolution during persistent infection in the stallion reproductive tract
Journal of Virology, 2019Co-Authors: Bora Nam, E L Squires, Zelalem Mekuria, Mariano Carossino, Ying Zheng, Jianqiang Zhang, Frank R Cook, Kathleen M Shuck, J R Campos, Mats H.t. TroedssonAbstract:Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a reproductive and respiratory disease of horses. Following natural infection, 10 to 70% of infected Stallions can become carriers of EAV and continue to shed virus in the semen. In this study, sequential viruses isolated from nasal secretions, buffy coat cells, and semen of seven experimentally infected and two naturally infected EAV carrier Stallions were deep sequenced to elucidate the intrahost microevolutionary process after a single transmission event. Analysis of variants from nasal secretions and buffy coat cells lacked extensive positive selection; however, characteristics of the mutant spectra were different in the two sample types. In contrast, the initial semen virus populations during acute infection have undergone a selective bottleneck, as reflected by the reduction in population size and diversifying selection at multiple sites in the viral genome. Furthermore, during persistent infection, extensive genome-wide purifying selection shaped variant diversity in the stallion reproductive tract. Overall, the nonstochastic nature of EAV evolution during persistent infection was driven by active intrahost selection pressure. Among the open reading frames within the viral genome, ORF3, ORF5, and the nsp2-coding region of ORF1a accumulated the majority of nucleotide substitutions during persistence, with ORF3 and ORF5 having the highest intrahost evolutionary rates. The findings presented here provide a novel insight into the evolutionary mechanisms of EAV and identified critical regions of the viral genome likely associated with the establishment and maintenance of persistent infection in the stallion reproductive tract.IMPORTANCE EAV can persist in the reproductive tract of infected Stallions, and consequently, long-term carrier Stallions constitute its sole natural reservoir. Previous studies demonstrated that the ampullae of the vas deferens are the primary site of viral persistence in the stallion reproductive tract and the persistence is associated with a significant inflammatory response that is unable to clear the infection. This is the first study that describes EAV full-length genomic evolution during acute and long-term persistent infection in the stallion reproductive tract using next-generation sequencing and contemporary sequence analysis techniques. The data provide novel insight into the intrahost evolution of EAV during acute and persistent infection and demonstrate that persistent infection is characterized by extensive genome-wide purifying selection and a nonstochastic evolutionary pattern mediated by intrahost selective pressure, with important nucleotide substitutions occurring in ORF1a (region encoding nsp2), ORF3, and ORF5.
-
presence of bacteria on the external genitalia of healthy Stallions and its transmission to the mare at the time of breeding by live cover
Journal of Equine Veterinary Science, 2014Co-Authors: Katheryn L Cerny, Mats H.t. Troedsson, Tom V Little, C F Scoggin, R J Coleman, E L SquiresAbstract:Abstract The current field study used thoroughbred Stallions and mares from central Kentucky to investigate the occurrence of potentially pathogenic bacteria on the stallion's external genitalia, based on cultures, and investigated the occurrence of bacteria and type of isolate in the mare's uterus after breeding by live cover to Stallions with or without positive bacterial cultures. Fifteen thoroughbred Stallions and 206 mares from two central Kentucky thoroughbred farms were used during the 2010 and 2011 breeding seasons. Samples for bacteriological evaluation were taken from the prepuce and postejaculate urethra (n = 201) of Stallions. Uterine swabs (n = 264) were collected 12-18 hours postbreeding. For statistical analyses, a chi-squared test was used to test the relationship between stallion culture results and postbreeding uterine culture results, as well as the effect of bacterial types found on the stallion cultures with bacterial types found on the postbreeding uterine cultures. Of stallion cultures, 22.4% were positive for potentially pathogenic bacteria, with Streptococcus equi subspecies zooepidemicus (51.1%) being the most common isolate. Uterine cultures resulted in a 29.2% positive rate for potentially pathogenic bacteria, with S. equi subsp. zooepidemicus (90.9%) being the most common. There was no difference ( P > .05) in the occurrence of bacteria or type of isolate found on uterine cultures after breeding Stallions with or without positive cultures. In conclusion, potentially pathogenic bacteria found on the stallion's external genitalia did not affect the occurrence and type of bacterial isolate found in the mare's uterus after breeding by live cover.
-
evaluation of alternative cryoprotectants for preserving stallion spermatozoa
Theriogenology, 2004Co-Authors: E L Squires, S L Keith, J K GrahamAbstract:Abstract Although use of cryopreserved stallion spermatozoa is currently accepted by many breed registries, utilization of this technique remains limited due to poor fertility for some Stallions. One reason for these results is osmotic stress that spermatozoa experiences when the cryoprotectant (glycerol) is added to the cells prior to freezing and removal from the cells after thawing. In an effort to minimize osmotic damage, alternative cryoprotectants, having lower molecular weights and greater membrane permeability than glycerol, were evaluated to determine their effectiveness for cryopreserving stallion spermatozoa. In the first experiment, equal molar concentrations of several amides were compared to determine if they could preserve the motility of sperm as well as glycerol. At 0.55 M concentration, addition of glycerol to a skim milk–egg yolk (SMEY) diluent resulted in higher percentages of motile sperm (61%) than methyl formamide (40%) or dimethyl formamide (38%, P P P >0.05). In conclusion, both methyl formamide and dimethyl formamide protected stallion spermatozoa from cryodamage as effectively as glycerol. Since these compounds permeate the plasma membrane more effectively than glycerol, they should cause less osmotic damage to stallion spermatozoa than glycerol. Therefore, these compounds may prove very effective in the cryopreservation of stallion spermatozoa, and may be particularly useful for spermatozoa from Stallions that produce spermatozoa that have poor post-thaw characteristics when glycerol is used as the cryoprotectant.
-
comparison of the fertility of cryopreserved stallion spermatozoa with sperm motion analyses flow cytometric evaluation and zona free hamster oocyte penetration
Theriogenology, 1996Co-Authors: K M Wilhelm, J K Graham, E L SquiresAbstract:Stallion spermatozoa were cryopreserved in different extenders, and the correlations between laboratory assay results and sperm fertility were determined. Spermatozoa were cryopreserved in 1) a skim milk-egg yolk medium (CO); 2) a skim milk-egg yolk-sugar medium (SMEY); 3) CO after pretreatment with phosphatidylserine+cholesterol liposomes (CO + L); or 4) cooled to 5°C without cryopreservation. The per cycle embryo recovery rates for mares inseminated with spermatozoa frozen in CO, SMEY, CO + L and spermatozoa cooled to 5°C were 47, 42, 45 and 37%, respectively (P>0.05). The fertility rates of the 5 Stallions used were 72, 71, 29, 25 and 16%, respectively (P 0.05). The percentages of motile spermatozoa after cryopreservation were not different across Stallions (52 to 58%) initially but were different when spermatozoa were treated with 35 μM dilauroylphosphatidylcholine (PC12) to induce the acrosome reaction (17 to 42%; P<0.05). The percentages of viable spermatozoa and viable acrosome-intact spermatozoa ranged from 30 to 57% and 27 to 48%, respectively, across Stallions. The percentages of penetrated hamster oocytes ranged from 19% to 55% and from 24% to 72% when spermatozoa were treated with 35 μM and 50 μM PC12, respectively. The number of spermatozoa penetrating each oocyte ranged from 0.21 to 1.16 sperm/oocyte and from 0.37 to 1.59 sperm/oocyte when spermatozoa were treated with 35 μM and 50 μM PC12, respectively. Analyses of single sperm parameters were not highly correlated with stallion fertility. However, a model utilizing data from flow cytometric analyses (percentage of viable spermatozoa), the percentage of motile spermatozoa, and hamster oocyte penetration (percentage of penetrated hamster oocytes) was highly correlated with stallion fertility (r = 0.85; P = 0.002).
-
comparison of the fertility of cryopreserved stallion spermatozoa with sperm motion analyses flow cytometric evaluation and zona free hamster oocyte penetration
Theriogenology, 1996Co-Authors: K M Wilhelm, J K Graham, E L SquiresAbstract:Stallion spermatozoa were cryopreserved in different extenders, and the correlations between laboratory assay results and sperm fertility were determined. Spermatozoa were cryopreserved in 1) a skim milk-egg yolk medium (CO); 2) a skim milk-egg yolk-sugar medium (SMEY); 3) CO after pretreatment with phosphatidylserine+cholesterol liposomes (CO + L); or 4) cooled to 5°C without cryopreservation. The per cycle embryo recovery rates for mares inseminated with spermatozoa frozen in CO, SMEY, CO + L and spermatozoa cooled to 5°C were 47, 42, 45 and 37%, respectively (P>0.05). The fertility rates of the 5 Stallions used were 72, 71, 29, 25 and 16%, respectively (P 0.05). The percentages of motile spermatozoa after cryopreservation were not different across Stallions (52 to 58%) initially but were different when spermatozoa were treated with 35 μM dilauroylphosphatidylcholine (PC12) to induce the acrosome reaction (17 to 42%; P<0.05). The percentages of viable spermatozoa and viable acrosome-intact spermatozoa ranged from 30 to 57% and 27 to 48%, respectively, across Stallions. The percentages of penetrated hamster oocytes ranged from 19% to 55% and from 24% to 72% when spermatozoa were treated with 35 μM and 50 μM PC12, respectively. The number of spermatozoa penetrating each oocyte ranged from 0.21 to 1.16 sperm/oocyte and from 0.37 to 1.59 sperm/oocyte when spermatozoa were treated with 35 μM and 50 μM PC12, respectively. Analyses of single sperm parameters were not highly correlated with stallion fertility. However, a model utilizing data from flow cytometric analyses (percentage of viable spermatozoa), the percentage of motile spermatozoa, and hamster oocyte penetration (percentage of penetrated hamster oocytes) was highly correlated with stallion fertility (r = 0.85; P = 0.002).
