The action of tubulosine on the mitotic cycle was studied using continuous labelling with tritiated thymidine. This alkaloid provokes a lengthening of the G1 and S phases and a blocking of G2 is totally reversible when the treatment is followed by recovery in normal medium.
At a dose of tubulosine which induces a reversible mitostasis in the shortest possible time the lengthening of the phases of the cell cycle was estimated by three different techniques: labelled mitoses for the determination of G2; labelling intensity for the determination of S; binucleate cells for the determination of T, and an original technique using labelling index of binucleate cells for the determination of G1.
The limits of the technique of labelled mitosis together with the interest of the technique aiming at the direct determination of G1 in the case of a perturbed cycle are then discussed.
The kinetics of binucleate cells, formed by the action of deoxyguanosine, are studied using three methods: in a population synchronized with hydroxyurea, by autoradiography after pulse‐labelling, and in a sample of a cell population morphologically located at the M‐G1, limit. Deoxyguanosine induces a slowing down in S and G2, independent of the inhibition of cytokinesis. It is only when it takes effect during the G2, stage that deoxyguanosine brings about the formation of binucleate cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.