SNP associations and genetic-parameter estimation for nose and hoof pigmentation in Corriedale sheep

Published Online 7/6/23 OnlinePublContext. Quantity and quality of both meat and wool are important for selection programs of the dual-purpose Corriedale sheep. In Corriedales, black pigmentation of nose skin and hooves is preferred as part of the breed standard. However, within the breed, pigmentation can vary from none to complete pigmentation. Aims. The aim was to discover single-nucleotide polymorphisms (SNPs) and genes associated with nose and hoof pigmentation and to estimate genetic parameters of nose and hoof pigmentation, wool traits and meat traits. Methods. The phenotype and genotype data on Corriedale lambs (n = 764) produced from 44 sires (12 studs) and 300 ewes in 2017–2019 were used in this study. Lambs were slaughtered at 6–7 months of age. Nose pigmentation and hoof pigmentation were scored on a five-point scale, where no pigmentation was scored 0 and complete pigmentation was scored 5. Wool-and meat-quality traits were measured, including greasy fleece weight, fibre diameter, weaning weight, hot standard carcass weight and intramuscular fat percentage. The lambs were genotyped with the GGPOvine50K SNP chip. A genome-wide association study (GWAS) was conducted. Genetic parameters and bivariate analyses were estimated using ASReml-R. Results. The lambs had a mean nose-pigmentation score of 3.69 and hoof-pigmentation score of 4.12. The nose pigmentation (h2 = 0.58) and hoof pigmentation (h2 = 0.51) were highly heritable and highly correlated (rG = 0.73). The GWAS identified a genome-wide significant SNP (OAR19_33278780.1) associated with nose pigmentation (q-value = 0.04). This SNP is positioned in a known pigmentation gene, melanocyte-inducing transcription factor (MITF ). The same SNP was the sixth-most associated SNP for hoof pigmentation but did not reach significance level. OAR19_33278780.1 also had a significant effect on back conformation and weaning weight. Conclusions. The results of these analyses have provided information and an understanding of the genetics for pigmentation of nose and hooves in Corriedale sheep. Implications. Nose and hoof pigmentation are highly genetically correlated with each other, but with no negative effects on production traits.J. E. Aldersey, M. S. Khatkar, P. J. Blackwood, C. E. Blackwood, J. M. Pitchford, H. Gordon, S. C. Welsh and W. S. Pitchfor

van der Waals coefficients for positronium-atom interactions

The van der Waals coefficients for positronium interactions with a number of rare gases (He, Ne, Ar, Kr, and Xe) and alkali-metal atoms (Li, Na, K, and Rb) are estimated using a variety of ab initio and semiempirical methods. Dispersion coefficients are also presented for atomic hydrogen and a number of rare-gas and alkali-metal atoms for validation purposes

Positronium scattering by the noble gases

The properties of positronium and the outcome of positronium collisions with other atoms and molecules are of interest in many areas of physics. For example, annihilation of orthopositronium has been detected originating from the centre of the Milky Way and observation of a fountain of positrons emitted orthogonally to the galactic plane has been recorded. Another application of positronium scattering data is to precision measurements of the lifetime of positronium carried out in gaseous mediaAvailable from British Library Document Supply Centre-DSC:DXN042875 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo