Development of 3T3‐like lines from Balb/c mouse embryo cultures: Transformation susceptibility to SV40

TLDR

Balb/c mouse embryo cultures kept on a rigid transfer schedule produce permanent lines that closely resemble 3T3, while extensive cell–cell contact yields Balb/3T12 lines with up to 25‑fold higher saturation densities, and all lines are hypotetraploid. Balb/3T3 lines exhibit morphology, high‑dilution growth, low saturation density, and high SV40 transformation susceptibility similar to 3T3, whereas Balb/3T12 lines show little cloning efficiency improvement, yet SV40 infection generates transformants selected by low‑density colony formation, indicating comparable SV40‑induced transformation in both line types.

Abstract

Abstract Balb/c mouse embryo cultures that are carried under a rigid transfer schedule that minimizes cell‐cell contact evolve into permanent lines that possess properties very similar to 3T3. From the same embryo cultures, a transfer schedule where cell‐cell contact is extensive leads to lines (Balb/3T12) that form multiple cell layers and have saturation densities up to 25‐fold higher than the Balb/3T3 lines. All the lines are hypotetraploid. Comparison of the Balb/3T3 lines with 3T3 reveals similar morphology, ability to grow at high dilution, low saturation density, and high susceptibility to transformation by SV40 virus. The Balb/3T12 lines, which are continually maintained at high cell density, show little improvement in cloning efficiency. Infection with SV40 produces transformants that can be selected by their ability to form colonies at low cell densities. Using the appropriate selective system for each line, it appears that SV40 T antigen induction and transformation in Balb/3T3 and Balb/3T12 are comparable.