Quantitative trait loci with parent-of-origin effects in chicken

Abstract

We investigated potential effects of parent-of-origin specific quantitative trait loci (QTL) in chicken. Two divergent egg-layer lines differing in egg quality were reciprocally crossed to produce 305 F2 hens. Searching the genome using models with uni-parental expression, we identified four genome-wide significant QTL with parent-of-origin effects and three highly suggestive QTL affecting age at first egg, egg weight, number of eggs, body weight, feed intake, and egg white quality. None of these QTL had been detected previously using Mendelian models. Two genome-wide significant and one highly suggestive QTL show exclusive paternal expression while the others show exclusive maternal expression. Each of the parent-of-origin specific QTL explained 3-5 % of the total phenotypic variance, with the effects ranging from 0.18 to 0.4 phenotypic SD in the F2. Using simulations and further detailed analyses, it was shown that departure from fixation in the founder lines, grand-maternal effects (i.e. mitochondrial or W-linked) and Z-linked QTL were unlikely to give rise to any spurious parent-of-origin effects. The present results suggest that QTL with parent-of-origin specific expression are a plausible explanation for some reciprocal effects in poultry and deserve more attention. An intriguing hypothesis is whether these effects could be the result of genomic imprinting, which is often assumed to be unique to eutherian mammals.

Phenotypic characterization of chicken inbred lines that differ extremely in growth, body composition and egg production traits

“…The same authors reported a mean of 59.2 g for egg weight, which was higher than in our inbred WL77 line. The higher age at first egg in our WL77 inbred line compared to other White Leghorn populations (SASAKI et al 2004, TUISKULA-HAAVISTO et al 2004) is due to the correlated response of selection for low egg weight before inbreeding.…”

Intralocus Sexual Conflict and the Genetic Architecture of Sexually Dimorphic Traits in Prochyliza Xanthostoma (Diptera: Piophilidae)

“…This pattern cannot be explained as a result of sex limitation or sex linkage but could readily result from genomic imprinting, with silencing of maternally inherited alleles in all offspring (Spencer 2002). Such parent-of-origin effects are known in a wide range of taxa, including Drosophila (Lloyd 2000), mammals (Monk 1987;Moore and Haig 1991;de Koning et al 2000;Rattink et al 2000;Goos and Silverman 2001;Moore 2001), birds (Tuiskula-Haavisto et al 2004), and plants (Alleman and Doctor 2000), and typically appear to play a role in the regulation of organ development and growth. Reduced autosomal recombination rate in males (Lenormand 2003) could contribute to this result.…”

Meiotic drive and sex determination: molecular and cytological mechanisms of sex ratio adjustment in birds

“…B (2008) chromosomes may facilitate their segregation. The long-standing assumption that genomic imprinting does not occur in oviparous species (Haig & Graham 1991) is challenged by the recent documentation of epigenetic marking of avian chromosomes ( Teranishi et al 2001;Tuiskula-Haavisto et al 2004;Gupta et al 2006). For example, DNA methylation changes the conformation of chromatin from compact to loose in the promoter of the vitellogenin gene in Japanese quail Coturnix japonica (Gupta et al 2006).…”

“…For example, DNA methylation changes the conformation of chromatin from compact to loose in the promoter of the vitellogenin gene in Japanese quail Coturnix japonica (Gupta et al 2006). In chickens, the presence of genomic imprinting is evident in differential expression of maternal and parental origin genes affecting egg production ( Tuiskula-Haavisto et al 2004). If offspring sex adjustment in birds is facilitated by sex chromosome recognition through genomic imprinting, then avian sex chromosomes should differ in methylation pattern.…”