Silver stained interphasic Nucleolus Organizer Regions (AgNOR) of embryonic tissues at two early stages from different selected lines of Japanese Quail has been examined with the help of a computer assisted image processing system. The following interphasic AgNOR parameters indicating a high or low transcriptional activity of the rDNA were measured, number and area of AgNOR (mean and total area of all AgNOR per nucleus). The results showed a significant (P< .001) decrease of the number and size of the interphasic AgNOR per nucleus at the later stage of early embryonic development. Embryonic tissues of individuals from lines with a high egg weight and relative high yolk weight showed within both stages of development a significant higher number and total area of AgNOR per nucleus than those from lines selected for high body weight and relative low yolk weight. Concerning the reason for these differences between the lines, further molecular biological studies are necessary, e.g. the analysis of the rRNA gene copy number. The chromosomes containing active metaphasic AgNORs belong to the so-called "microchromosomes". The average number was 5.07 (±0.26) and no significant differences between the stages of early embryonic development were determined (P>.05).

K. U Wagner, L. Schueler, M. Apitz, W. Saar

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 21. Gene mapping; polymorphisms; disease genetic markers; marker assisted selection; gene expression; transgenes; non-convention, , 320–323, 1994
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