A reversible block at the G1/S border during cell cycle progression of mouse embryos.
Late 2-cell stage mouse embryos were cultured in M-199 plus 100 micrograms/ml Na pyruvate 25 micrograms/ml gentamycin and 0.3% BSA with or without mimosine (200 microM, 150 microM, 100 microM and 50 microM) for a short (4-5 h) or long (18-20 h) culture period; after drug removal subsequent embryo development was evaluated. Late 2-cell stage mouse embryos treated with mimosine were blocked at the 4-cell stage. Autoradiographic studies show that mimosine inhibits cell cycle progression in mouse embryos at the G1/S boundary. The onset of DNA replication occurs within 15 min of releasing the embryos from mimosine block. Embryos pretreated with mimosine at 200 microM and 150 microM for 4-5 h progress after 3-4 days in culture to hatched blastocyst (71% and 79%, respectively) compared with control (90%). However a longer pretreatment (18-20 h) with mimosine at 200 microM was significantly detrimental to the subsequent developmental progression to hatched blastocyst (2% vs 81%, p < or = 0.05); the proportion of degenerated embryos was significantly increased with mimosine at 200 microM and 150 microM compared with control (57% and 28% vs 4%, p < or = 0.05) after 3-4 days in culture. Preliminary studies with mimosine treatment at 100 microM and 50 microM for 18-20 h show that 70% and 37% of the embryos were blocked at 4-cell stage, respectively. These results indicate that mimosine inhibits cell cycle progress in mouse embryos at the G1/S border and thus induces a reversible arrest in a dose- and time-dependent manner.
Ouhibi
N
N
Babraham Institute, Development and Differentiation Laboratory, Cambridge, United Kingdom.
Fulka
J
J
Kanka
J
J
Moor
R M
RM
D000818:Animals; D001345:Autoradiography; D001755:Blastocyst / Q000166:cytology; D001973:Bromodeoxyuridine / Q000032:analysis; D046508:Culture Techniques; D005455:Fluorescent Antibody Technique; D016193:G1 Phase / Q000187:drug effects*; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008898:Mimosine / Q000008:administration & dosage / Q000494:pharmacology*; D016196:S Phase / Q000187:drug effects*; D015053:Zygote / Q000166:cytology*
D008898:Mimosine; D001973:Bromodeoxyuridine