1. Editor's announcement

   EditorialNotes Pages: 401 - 401

2. Note from the publishers

   Legacy Pages: 402 - 402

3. In vitro cleavage of 45S pre-ribosomal RNA and of giant heterogeneous RNA extracted from human leukemic cells

   • U. L. Torelli
   • St. Ferrari
   • F. Narni

   OriginalPaper Pages: 403 - 411

4. Cleavage of pm⁷G from mRNA 5′terminal cap structures by pyrophosphatase activity in embryonic chick lens cells

   • Gene C. Lavers

   OriginalPaper Pages: 413 - 420

5. Stabilization of mRNA following serum-induction of quiescent 3T3 cells

   • Everet Bandman

   OriginalPaper Pages: 421 - 428

6. Low molecular weight peptides controlling transcription are present in the calf thymus chromatin structure

   • G. L. Gianfranceschi
   • L. Guglielmi
   • R. Petruzzelli

   OriginalPaper Pages: 429 - 436

7. Repair of DNA double-strand breaks requires two homologous DNA duplexes

   • A. N. Luchnik
   • V. M. Glaser
   • V. Shestakov

   OriginalPaper Pages: 437 - 442

8. The action of structural analogues of ethidium bromide on the mitochondrial genome of yeast

   • Ruth M. Hall
   • John S. Mattick
   • Anthony W. Linnane

   OriginalPaper Pages: 443 - 449

9. Restriction endonuclease analysis of the transducing bacteriophage lambda rif d18

   • Imre Boros
   • Béla Sain

   OriginalPaper Pages: 451 - 457

10. Effect of ethionine on the rough endoplasmic reticulum from male and female rat liver

    • H. H. Czosnek
    • A. Ascarelli
    • A. A. Hochberg

    OriginalPaper Pages: 459 - 466

11. Erratum

    Erratum Pages: i - i