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The composition of liver chromatin proteins from embryos, chicks and adult chickens
Insights
Chromatin composition changes during chicken development, with non-histone proteins and RNA increasing in embryos and decreasing post-hatching. Histone H1 and specific non-histone protein fractions also show age-related variations.
Area of Science:
- Biochemistry
- Developmental Biology
- Molecular Biology
Background:
- Chromatin structure and composition are critical for gene regulation during development.
- Understanding age-related changes in chromatin provides insights into cellular differentiation and function.
Purpose of the Study:
- To analyze the chemical composition of liver chromatin in chickens at various developmental stages.
- To identify age-dependent alterations in chromatin proteins, RNA, and phosphoproteins.
Main Methods:
- Chromatin was isolated from chicken livers at embryonic (12, 15, 19 days), post-hatch (1 day), and adult stages.
- Analysis included quantification of non-histone proteins, chromatin RNA, and phosphoprotein phosphorus content.
- Two-dimensional polyacrylamide gel electrophoresis was used to characterize acid-soluble chromatin proteins and non-histone protein fractions.
Main Results:
- Non-histone chromatin proteins and chromatin RNA increased during embryonic development, then decreased in post-hatch and adult livers.
- Phosphorus content in chromatin phosphoproteins followed a similar pattern to non-histone proteins and RNA.
- Histone H1 levels increased in 19-day embryos and adult chickens.
- Specific non-histone protein fractions (Mr ~40,000 in embryos; Mr ~120,000 in adults) exhibited distinct age-related presence and abundance.
Conclusions:
- Chicken liver chromatin undergoes significant compositional changes throughout embryonic development and into adulthood.
- These changes involve dynamic alterations in non-histone proteins, histone H1, and chromatin RNA content.
- The observed molecular differences highlight stage-specific chromatin organization crucial for developmental transitions.
Abstract:
The chemical composition of chromatin from the livers of 12-, 15- and 19-day-old embryos, of 1-day-old chicks and of adult chickens was analysed. The process of embryonic development is accompanied by an increase in non-histone chromatin proteins and chromatin RNA, as well as in the phosphorus content of chromatin phosphoproteins. The amount of these components decreases in the livers of 1-day-old chicks and adults. Two-dimensional polyacrylamide gel electrophoresis of acid-soluble chromatin proteins showed an increase in the amount of the H1 histone in 19-day-old embryos and adult chickens. Non-histone proteins of embryo liver chromatin showed a high content of the fraction of Mr of about 40 000; this was not the case for adult chickens. The non-histone protein fraction of Mr of about 120 000, characteristic of adult chicken liver proteins, was not found in the livers of 12- and 15-day-old embryos. Non-histone chromatin proteins isolated from the livers of animals of different age exhibited also quantitative differences.