INVITRO INDUCTION OF EARLY MOUSE EMBRYO INTRACISTERNAL PARTICLES (EPSILON-PARTICLES) IN CULTURED-CELL LINES

The experimental induction of epsilon-particles, retrovirus-like structures corresponding to the small IA particles of the mouse, was studied by electron microscopy in rodent-cultured cell lines. Among the chemicals tested, only IdUr was shown to be an effective inducer, but not cycloheximide, puromycine, deoxy-fluorouracile or 5-azacytine. However, only two mouse-derived cell lines: Ki-BALB and FG 10, among 27 cell lines of mouse, rat and mink origins tested, expressed-epsilon-particles upon IdUr treatment. Epsilon particles thus respond to chemical inducers very differently in comparison with large IAP. Moreover, the addition of interferon previously shown to attenuate IAP production, had no effect on that of epsilon-particles.