Expression of sea urchin histone genes in the oocyte of Xenopus laevis (original) (raw)

1979, Journal of Molecular Biology

h22, the cloned repeat unit of Psammechinus miliaris histone genes, is transcribed and translated when inject.ed into Xenopus oocyte nuclei. Transcription is mediated by polymerase B. RNAs indist.inguishable from sea urchin histone mcsscngtr RNAs H2A and H2B are synthesized, but' a large portion of transcripts is polydisperse. From hybridization experiments it can be dcduccd that the H2A and H2B messenger RNAs hybridize rxclusively to the coding strand of the stfructural genes, whereas polydisperse RNA is homologous t,o both strands of the repeat unit. h22 transcripts are stable in t,he oocyt,e and direct the synthesis of sea urchin histone proteins H2A and H2B. h22 transcript,s were isolated separately from oocytr nuclei and cytoplasm. The cytoplasmic RNA contained virtually all of the sea urchin HZA and H2B ml%NAs, and some minor RNAs of discret,e size. On t.hf> other hand, polytlispcrse RNA and RNA complementary to the antisense strand of h22 DNA remained in the nucleus. Covalent circrdarit,y of the h22 DNA seemed to be an importa,nt, factor for the mode of transcriptSion, since only circular h22 and circular pCRI-h22, but not linearized h22, produced H2B mRKA. These findings camphasize special, new aspects for both DNA t,ranscription and RNA processing and transport wit,hin tho living cell.