Hmr^EY12237 suppresses hybrid male lethality of hybrid males derived from a cross between D. melanogaster females and D. simulans males.

At 27[o]C, homozygous females produce significantly fewer progeny at all time points tested compared to heterozygous controls.

At 28[o]C, homozygous females aged 3-4 days lay significantly fewer eggs than heterozygous controls. Hatchability and eclosion of adults occurs at a lower frequency in eggs from homozygous females.

Ovaries from 5 day old virgin homozygous females grown at 28[o]C are somewhat smaller than those of control siblings In ovaries from homozygous females raised at 29[o]C, no major morphological defects are seen in 5 day old flies, but in 15-17 day old flies, ovariole development is defective in approximately half of those examined, while the other half appear normal. The abnormal class of ovaries contain ovarioles in which the anterior end is stub-like rather than tapered in shape (as in wild type). The stub-like ovarioles do contain egg chambers, but the egg chambers are squished into the anterior end of the ovarioles. Some of the egg chambers are intact, but many appear disrupted, for example having scattered nurse cell nuclei. The somatic follicle cells appear to be smaller than normal and reduced in number in the defective ovarioles.