Y-Chromosomal Insights into Breeding History and Sire Line Genealogies of Arabian Horses.

The Y chromosome is a valuable genetic marker for studying the origin and influence of paternal lineages in populations. In this study, we conducted Y-chromosomal lineage-tracing in Arabian horses. First, we resolved a Y haplotype phylogeny based on the next generation sequencing data of 157 males from several breeds. Y-chromosomal haplotypes specific for Arabian horses were inferred by genotyping a collection of 145 males representing most Arabian sire lines that are active around the globe. These lines formed three discrete haplogroups, and the same haplogroups were detected in Arabian populations native to the Middle East. The Arabian haplotypes were clearly distinct from the ones detected in Akhal Tekes, Turkoman horses, and the progeny of two Thoroughbred foundation sires. However, a haplotype introduced into the English Thoroughbred by the stallion Byerley Turk (1680), was shared among Arabians, Turkomans, and Akhal Tekes, which opens a discussion about the historic connections between Oriental horse types. Furthermore, we genetically traced Arabian sire line breeding in the Western World over the past 200 years. This confirmed a strong selection for relatively few male lineages and uncovered incongruences to written pedigree records. Overall, we demonstrate how fine-scaled Y-analysis contributes to a better understanding of the historical development of horse breeds.

Restoration of functional sperm production in irradiated pubertal rhesus monkeys by spermatogonial stem cell transplantation.

BACKGROUND: In male pre-pubertal cancer patients, radiation and chemotherapy impact future fertility by eradication of spermatogonial stem cells (SSCs). In macaques, spermatogenesis could be regenerated by intratesticular transplantation of SSCs, but only a small percentage of spermatozoa produced were of donor origin. Transient hormone suppression with a GnRH antagonist (GnRH-ant) enhanced spermatogenic recovery from transplanted SSCs. OBJECTIVES: To evaluate donor-derived and endogenous spermatogenic recovery after SSC transplantation into irradiated monkeys and to test whether hormone suppression around the time of transplantation facilitates spermatogenic recovery. MATERIALS AND METHODS: Testes of 15 adult rhesus monkeys were irradiated with 7 Gy and 4 months later transplanted, to one of the testes, with cryopreserved testicular cells containing SSCs from unrelated monkeys. Monkeys were either treated with GnRH-ant for 8 weeks before transplantation, GnRH-ant from 4 weeks before to 4 weeks after transplantation, or with no GnRH-ant. Tissues were harvested 10 months after transplantation. RESULTS: Two of the 15 monkeys, a control and a pre-transplantation GnRH-ant-treated, showed substantially higher levels of testicular spermatogenesis and epididymal sperm output in the transplanted side as compared to the untransplanted. Over 84% of epididymal spermatozoa on the transplanted side had the donor genotype and were capable of fertilizing eggs after intracytoplasmic sperm injection forming morulae of the donor paternal origin. Low levels of donor spermatozoa (~1%) were also identified in the epididymis of three additional monkeys. Transplantation also appeared to enhance endogenous spermatogenesis. DISCUSSION AND CONCLUSION: We confirmed that SSC transplantation can be used for restoration of fertility in male cancer survivors exposed to irradiation as a therapeutic agent. The success rate of this procedure, however, is low. The success of filling the tubules with the cell suspension, but not the GnRH-ant treatment, was related to the level of colonization by transplanted cells.

Molecular epidemiology of coagulase-negative Staphylococcus species isolated at different lactation stages from dairy cattle in the United States.

BACKGROUND: Coagulase negative Staphylococcus (CNS) species are currently the most prevalent intra-mammary pathogens causing subclinical mastitis and occasional clinical mastitis or persistent infection in lactating dairy cattle. More than 10 CNS species have been identified, but they are generally managed as one group on most dairies in the United States. However, improved management decisions and treatment outcomes may be achieved with better understanding of the prevalent species, pathogenicity and strain diversity within and across dairies. METHODOLOGY: A total of 604 CNS isolates were cultured from milk samples collected during a dry-cow treatment clinical trial conducted on 6 dairy herds in 4 states in the US. All the study cows were randomized to receive 1 of the 3 different intra-mammary antimicrobial infusions (Quatermaster, Spectramast DC or ToMorrow Dry Cow) at dry-off. Milk samples were collected at dry-off, calving (0-6 days in milk, DIM), post-calving (7-13 DIM) and at mastitis events within the first 100 DIM. The CNS isolates were identified to species level by partial sequencing of the rpoß gene, and genetic relatedness within species was investigated by phylogenetic analysis of the pulse-field gel electrophoresis profiles of the isolates. RESULTS: The major CNS species identified were S. chromogenes (48.3%), S. haemolyticus (17.9%), S. simulans and S. epidermidis (each at 6.5%). Other CNS species identified at lower frequencies included S. hominis, S. auricularis, S. sciuri, S. spp KS-SP, S. capitis, S. cohnii, S. warneri, S. pasteuri, S. xylosus, S. hyicus, S. equorum, S. microti, S. rostri, S. gallinarum, S. saprophyticus and S. succinus. Phylogenetic analyses of the major species types demonstrated an association between genetic relatedness and epidemiological distributions of S. chromogenes, S. simulans, S. haemolyticus and S. auricularis. Additionally, identical strains of S. chromogenes and S. simulans were isolated from the same udder quarter of several cows at consecutive sample stages. The rest of the minor species had no deducible genetic-epidemiological link. DISCUSSION: The observed association between genetic and epidemiological distributions indicated animal-adapted nature of four CNS species, suggesting possible host-adapted and environmental transmission of these species. Multi-stage isolation of the same udder quarter strain was evidence for chronic intra-mammary infection. CONCLUSION: The different CNS species and strains circulating on US dairy herds were genetically diverse. Four species identified were likely udder-adapted pathogens, 2 of which caused persistent infection. Our findings are important in guiding the design of effective mastitis control strategies.