title: A discrete LINE-1 transcript in mouse blastocysts.
abstract: The LINE-1 (L1) repetitive elements of mammalian genomes are retrotransposons lacking LTRs; L1-encoded reverse transcriptase probably mediates an important step in the generation of new copies. Most L1 transcripts are nonspecific, but discrete full length transcripts are present in embryonal carcinoma cells. We report here an abundant L1 transcript in mouse blastocysts but not in oocytes. The transcript is about 8 kb, sense strand, polyadenylated, and includes the 5' end of the two open reading frames. We propose that retrotransposition which generates pseudogenes and mammalian SINES as well as the L1 family occurs around the blastocyst stage of the germ cell cycle.
authors.affiliation: Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021.
authors.forename: A I
authors.initials: AI
authors.lastname: Packer
authors.forename: K
authors.initials: K
authors.lastname: Manova
authors.forename: R F
authors.initials: RF
authors.lastname: Bachvarova
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D015152:Blotting, Northern; D004251:DNA Transposable Elements; D005333:Fetus / Q000502:physiology; D015870:Gene Expression; D016678:Genome; D008099:Liver / Q000502:physiology; D051379:Mice; D009865:Oocytes / Q000502:physiology; D012313:RNA / Q000235:genetics* / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D004251:DNA Transposable Elements; D012313:RNA