3H-thymidine incorporation at the end of the S phase in cultured human lymphocytes

Summary Cultured human lymphocytes of female origin were exposed to 3 Ci/ml ³H-thymidine for 2, 21/4, 21/2, 23/4, and 3 hrs, respectively; a proportion of 0, 1.95, 6.4 and 16.7% of labeled metaphases were found among a total of over 3000 metaphases examined. 25 metaphases with little overall radioactivity were analyzed in detail by grain count and grain distribution. Earlier studies were confirmed that the grain distribution at the extreme end of the S phase is non-random in several regions of the chromosomal complement, but that a distinct interval (Z interval) probably does not exist.

---

Zusammenfassung In der vorliegenden Arbeit wird das Ende der DNA-Synthese mittels autoradiographischer Methoden an normalen menschlichen Lymphocyten untersucht. Das Reduplikationsverhalten der Chromosomen am Ende der DNA-Synthese wird näher beschrieben und diskutiert.Das Reduplikationsmuster der letzten 30 min der S-Phase als auch das Verhalten des späten X-Chromosoms sowie der Vergleich zum Markierungsverhalten der Autosomen sprechen gegen die Existenz eines sogenannten Z-Intervalls am Ende der Synthese-Phase.

---

---

This investigation was supported in part by grants from the Deutsche Forschungsgemeinschaft and is part of a thesis by D. B. in fulfillment of requirements for the M. D., at the University of Hamburg.