| In the newly fertilized embryo, meiotic and mitotic spindles form consecutively within the same egg cytoplasm. The order of events during this transition is controlled, in part, via the regulation of the microtubule cytoskeleton. Herein, I show that mel-43 is part of a small paralogous gene family that is required to specify the meiosis II program of cell division in the fertilized egg. RNAi of mel-43 and paralogues resulted in failed meiosis I polar body extrusion, followed by direct entry into mitotic prophase. Furthermore, the dominant maternal-effect mutation mel- 43(sb41) showed a meiosis-to-mitosis transition delay and a failure to segregate chromatids that exhibited persistent REC-8/kleisin immunostaining. Anti-MEL-43 antibodies showed that the MEL-43 proteins exhibited high cytoplasmic levels in meiosis as well as a fibrous staining pattern in the midzone of the anaphase spindle. The protein levels were reduced after meiosis, and this was dependent on the CUL-2/ZYG-11 E3 ligase complex. |
