[The role for nucleus-associated polyribosomes in the coordination of histone synthesis with replication of chromosomal DNA in loach embryonic cells]

Abstract

During intensive chromosome replication in loach (Misgurnus fossilis) embryonic cells a particular class of nucleus-associated polyribosomes has been discovered alongside the free and membranebound polyribosomes. The comparison of the translational patterns of these three polyribosome classes in in vivo and in vitro conditions has proved their metabolic and functional difference. It has been shown that the nucleus-associated polyribosomes comprising over 50 per cent of all the cell polyribosomes in the above-mentioned period produce the bulk of lysine-rich histones on the newly formed mRNAs. Using metabolic inhibitors of DNA, or RNA, or protein synthesis it has been established that the nucleus-associated polyribosome functional activity as differs from that of free and membrane-bound polyribosomes and depends to great degree on the chromosomal DNA replication and the shortliving mRNAs transcription. The data obtained suggest that the chromatin biogenesis control can be achieved by spacial coupling between DNA replication and histone synthesis at the nuclear envelope level.