Ovalbumin mRNA in the magnum of laying hens changes during egg formation cycle.

1. The aim of the present study was to determine if ovalbumin messenger RNA (mRNA) in the magnum of laying hens changes during the egg formation cycle. 2. The concentration of ovalbumin mRNA in the magnum was measured by RNA:RNA hybridisation in solution. The concentration of ovalbumin mRNA was higher when an ovum was in the magnum than when it was in the infundibulum. These changes in ovalbumin mRNA were essentially parallel to those in ovalbumin synthesis during the egg formation cycle as reported by Muramatsu et al. (1991). 3. The extent to which the ovalbumin mRNA was increased when an ovum moved down from the infundibulum to the magnum appeared to be too small to account for the expected increase in ovalbumin synthesis. This implies that in laying hens, translational rather than transcriptional regulation of ovalbumin synthesis is likely to be of primary importance.