Low-fecundity dhc-1; mel-28 C. elegans mutants do not have gonad mitosis defects

In C. elegans , dhc-1 ( or283 ); mel-28 ( t1684 ) double mutants have a severely reduced brood size compared with each single mutant and compared to the wild type. To determine if this synthetic low-fecundity phenotype is due to reduced potential to produce gametes, we studied gonad length and distal gonad mitotic activity in dhc-1 ( or283 ) mutants, mel-28 ( t1684 ) mutants, wild-type animals, and dhc-1 ( or283 ); mel-28 ( t1684 ) double mutants. Gonad length in dhc-1 ; mel-28 double mutants was the same as the wild type. Using an antibody against phosphorylated histone H3 (PH3), we tracked mitotic activity in mutant and wild-type gonads. We found no significant difference in mitotic activity between the double mutant and the wild-type. These observations suggest that the reduced brood size in dhc-1 ; mel-28 double mutants is not caused by a mitotically-inactive gonad and instead has a different and yet-to-be-determined basis.