Monoclonal antibody raised against human mitotic cyclin B1, identifies cyclin B-like mitotic proteins in synchronized onion (Allium cepa L.) root meristem.

Cyclin B-like mitotic proteins have been detected in synchronized Allium cepa L. root tip cells by using mouse monoclonal anti-cyclin B1 antibody raised against human cyclin B1. Immunoblot shows two closely placed isoforms of cyclin B-like proteins having an apparent molecular weight around 54 kDa. In vivo [35S]-methionine labelling followed by immunoprecipitation and autoradiography indicates that cyclin B-like proteins are mainly synthesized in the G2 phase of the cell cycle and destroyed in late mitosis. Immunoblotting data depict that the level of cyclin B-like proteins reaches the maximum at the late G2 to early M phase; and it becomes degraded in the late hours of mitosis. Moreover, the cyclin B isoforms are stabilized in colchicine-arrested metaphase cells as already reported in animal cells.