Correction of the maternal effect linked to the ac mutation, by injury of the egg, in the salamander Pleurodeles waltlii

Abstract

At the gastrula stage, deep irregular furrows appear on the animal hemisphere in embryos arising from ac/ac females and characterize a maternal effect (Beetschen, 1970). Disturbed morphogenetic movements (epiboly and invagination) frequently elicit exogastrulation or anomalies of later embryonic development. Pricking the animal hemisphere of the uncleaved egg with a micropipette prevents the occurrence of anomalies during gastrulation and neurulation in many embryos. Injection of normal oocyte nuclear sap or of normal egg cytoplasm into mutant female eggs does not improve that result. The partial correction of the maternal effect therefore appears to be consecutive to the injury of the cortical cytoplasm and/or the plasma membrane. Assuming that activation could be deficient, an electric shock was applied to freshly laid fertilized mutant eggs. It did not correct ectodermal anomalies but nevertheless seemed to increase the corrective effect of pricking when both treatments were applied.