Unable to propagate indefinitely: lines become sterile from F10-F28, with short telomeres and fused chromosomes. Hypersensitive to X-irradiation; weak Him phenotype; strong Him phenotype in later generations resulting from X-A fusions. Cross once or twice, freeze down many F2 mrt-2 plates, and go back to these plates every two months for fresh a mrt-2 line. A BstN1 RFLP makes the mrt-2 mutation easy to track.

Heterozygotes are WT and segregate WT, DpySteriles, and Uncs which give only dead eggs.