Fig. 7. CSN5 mutations activate a mei-41-dependent meiotic checkpoint. (A) In wild type, Grk protein is detectable in region 2a of the germarium and is restricted to the oocyte from region 3 onwards. (B) In CSN5^ex21/CSN5^L4032 germaria, Grk is undetectable. (C) Loss of mei-41 restores Grk expression in CSN5^ex21/CSN5^L4032 heterozygotes. (D,E) CSN5 mutations affect the mobility of Vasa protein. (D) An anti-Vasa western blot of ovarian extracts shows retarded Vasa migration in CSN5^L4032 germline clones. (E) An anti-Vasa western blot of ovarian extracts from several CSN5 allelic combinations. In wild type, Vasa migrates as a single 72 kDa band. Vasa migrates as two bands in CSN5^ex13/CSN5^L4032 and CSN5^ex21/CSN5^L4032. Notice, that in the stronger combination (CSN5^ex21/CSN5^L4032) more Vasa protein migrates slowly than in the weaker combination (CSN5^ex13/CSN5^L4032). Furthermore, in CSN5^ex13/CSN5^L4032, Vasa is fully restored to normal mobility by removal of one dose of mei-41, while CSN5^ex21/CSN5^L4032 requires homozygous mei-41 for normal Vasa mobility. Removing one dose of mei-W68 is sufficient to restore Vasa mobility in both hypomorphic, CSN5-mutant combinations. A second mei-W68 allele (mei-W68¹) had a weaker effect. As a heterozygote with the CSN5-mutant combinations, it gave only a partial rescue of Vasa mobility, although the mei-W68¹/mei-W68^k05603 combination resulted in full rescue of Vasa mobility (data not shown).