Onset of RNA synthesis and poly (A) content of early rabbit embryos. Comparison with sheep.
RNA synthesis in 2-32 cell embryos, as assessed by alpha-amanitin-sensitive 3H-uridine incorporation, was first detectable in 4-cell stage rabbit and 8-cell stage sheep embryos. In the rabbit, uridine incorporation was detectable at the 2-cell stage but was unaltered by alpha-amanitin, indicating synthesis of non-polymerase II-dependent RNA species. Initiation of mRNA synthesis as determined by in situ hybridization with 3H-poly (U) probe was first detectable in late 2-cell stage rabbit and 4-cell stage sheep embryos. In the rabbit embryos, nuclear labelling increased from the late 2-cell stage to the 16-cell stage, following a pattern similar to that of 3H-uridine incorporation. In contrast, the intensity of cytoplasmic labelling decreased from the 1- to the 8-cell stage and then increased up to the 32-cell stage. In sheep embryos, nuclear labelling by the poly (U) probe increased from the 4- to the 16-cell stage. It is concluded that initiation of transcription of the embryonic genome (mRNA) can be detected via the current methods used at the 4-cell stage in the rabbit and the 8-cell stage in the sheep.
Kanka
J
J
Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Libĕchov.
Fléchon
J E
JE
Sutovský
P
P
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D001345:Autoradiography; D001755:Blastocyst / Q000378:metabolism*; D017403:In Situ Hybridization; D011061:Poly A / Q000378:metabolism*; D012313:RNA / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits / Q000196:embryology* / Q000378:metabolism; D012756:Sheep / Q000196:embryology* / Q000378:metabolism; D013045:Species Specificity; D014158:Transcription, Genetic / Q000187:drug effects
D000546:Amanitins; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA