Domestic Fowl Breed Variation in Egg White Protein Expression: Application of Proteomics and Transcriptomics

Avian
egg white is essential for protecting and nourishing bird embryos
during their development. Being produced in the female magnum, variability
in hen oviduct gene expression may affect egg white composition in
domestic chickens. Since traditional poultry breeds may represent
a source of variation, in the present study we describe the egg white
proteome (mass spectrometry) and corresponding magnum transcriptome
(high-throughput sequencing) for 20 hens from five domestic fowl breeds
(large breeds: Araucana, Czech golden pencilled, Minorca; and small
breeds: Booted bantam, Rosecomb bantam). In total, we identified 189
egg white proteins and 16391 magnum-expressed genes. The majority
of egg white protein content comprised proteins with an antimicrobial
function. Despite general similarity, Between-class Principal Component
Analysis revealed significant breed-specific variability in protein
abundances, differentiating especially small and large breeds. Though
we found strong association between magnum mRNA expression and egg
white protein abundance across genes, coinertia analysis revealed
no transcriptome/proteome costructure at the individual level. Our
study is the first to show variation in protein abundances in egg
white across chicken breeds with potential effects on egg quality,
biosafety, and chick development. The observed interindividual variation
probably results from post-transcriptional regulation creating a discrepancy
between proteomic and transcriptomic data.