Assisted suicide of a selfish gene.
Medea (M) factors and the hybrid incompatibility factor (H) are involved in two incompatibility systems in flour beetles that were previously thought to be independent. M factors are a novel class of selfish genes that act by maternal lethality to nonself. The H factor causes the death of hybrids with a paternally derived H gene and previously uncharacterized maternal cofactors. We now find that M factors exhibit their selfish behavior only in the absence of the H factor. Furthermore, we show that the previously uncharacterized maternal cofactors required for H-associated hybrid inviability are identical to M factors. We propose that incompatibility between H strains and M strains is due to suppression by the H factor of the self-rescuing activity of the lethal M genes. This interaction has the effect of converting M elements from selfish into self-destructive or "suicidal" genes. M factors are globally widespread, but are conspicuously absent from India, the only country where the H factor is known to occur. Such a mechanism could prevent the spread of selfish M elements by establishing an absolute barrier to hybridization in the boundary between M and non-M zones.
Thomson
M S
MS
Department of Biological Sciences, University of Wisconsin-Parkside, Kenosha, USA.
Beeman
R W
RW
D000818:Animals; D002678:Chimera / Q000235:genetics; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins; D005785:Gene Conversion; D005804:Genes, Lethal / Q000235:genetics*; D006824:Hybridization, Genetic / Q000235:genetics*; D051901:Smad4 Protein; D013696:Temperature; D015534:Trans-Activators / Q000235:genetics*; D014231:Tribolium / Q000235:genetics*