Abstract #M93

# M93
Evolution of mutational variance associated with age and sex of the parent for weaning weight in C57BL/6J mice.
Mayela Castillo1, Juan F. Medrano2, Joaquim Casellas*1, 1Universitat Autònoma de Barcelona, Bellaterra, Spain, 2University of California, Davis, CA.

New mutations are a very relevant component of polygenic variability and they must be viewed as the raw material for the maintenance of genetic diversity. Nevertheless, the biological phenomena that originate new mutational variants are poorly understood, particularly in regard to the effects that factors such as a parent’s age may have. This research focuses on the analysis of weaning weight (10.48 ± 0.02 g) in 12,644 C57BL/6J mice from 46 non-overlapping generations. Data (y) were analyzed under the following model: y = Xb + Z1p + Z2a + Z2mp + Z2mm + e, where systematic (b), permanent environmental (p), and additive genetic effects (a, mp and mm) were linked by appropriate incidence matrices (X, Z1 ande Z2). Note that mutational effects where modeled depending on their origin (i.e., paternal, mp; maternal, mm), and an independent set of parent-specific mutational effects were estimated on the basis of new mutations arising to each individual in the pedigree file (i.e., mp = mp,1 + mp,2 + … + mp,12644). Within this context, mp,i was assumed multivariate normal (MVN) distributed, p(mp,i|Mimp2p) = MVN(0,0.5Miσmp2 [1+εp,iλp])Mi being the matrix of mutational relationships specific to new mutations arising in the ith individual, σmp2mm2) being the paternal (maternal) mutational variance, εp,i being sire's age when conceiving ith individual, and λp being a linear regression coefficient linking mutational variance and sire's age. This model was solved under a standard Bayesian approach. Mode (and credibility interval) for σmp2 and σmm2 were 0.113 (0.069 to 0.163) and 0.052 (0.020 to 0.097), respectively. Whereas linear regression coefficient for dam's age collapsed to 0 and discarded additional changes in σmm2, λp reached a modal estimate of 0.001 (10−5 to 0.051); e.g., this linearly increased σmp2 from ~0.11 g2 (puberal sires) to 0.154 g2 (one-yr-old sires). This parameterization allowed us to clearly characterize different mutational patterns associated with the sex of the parent, as well as the effect of the accumulation of new mutations along breeding stock’s lifetime.

Key Words: age-related mutation, C57WL/6J, weaning weight