Transcriptional perturbations associated with the actions of maternal-effect, selfish genes in the red flour beetle, Tribolium castaneum
Susan J. Brown, KSU Division of Biology
Richard W. Beeman, Department of Entomology and
   USDA ARS Grain Marketing and Production Research Center
Marcé D. Lorenzen, Department of Entomology and USDA ARS
   Grain Marketing and Production Research Center

PROJECT SUMMARY
Maternal-Effect Dominant Embryonic Arrest (Medea) genes are a novel class of maternally-acting, selfish genes that are widespread in natural populations of Tribolium, but are completely unknown in the remainder of the invertebrate world. Medea (M) genes are unique in combining a “maternal poison” and a “zygotic antidote” to gain a postzygotic survival advantage. M factors are also lethal in combination with the hybrid-incompatibility factor H. M1, one of two known 3rd linkage group M loci, was positionally cloned, and proved to be associated with a 21-kb insertion adjacent to a 230-nt hairpin. While the M1 region has been characterized molecularly, the detailed mechanisms of maternal lethality, zygotic protection, and H-incompatibility are still a mystery. The specific goals of this project are to: 1) develop Tribolium-specific whole-transcriptome microarrays and whole-genome tiling arrays; 2) compare transcriptomes of M1M4/H, M1/+, M1 and H prior to the time of M-induced developmental arrest; 3) conduct a genome-wide survey of microRNA expression in above genotypes prior to the time of M-induced developmental arrest; and 4) use quantitative RT-PCR to verify M-associated misregulation of identified transcripts. Data from this seed grant will be used to support a full proposal to NSF or CSREES-NRI on the molecular mechanisms of M and H incompatibility. Components of the full proposal will include: (1) the use of the jumpstarter insertional-mutagenesis system to generate transposon insertions flanking the M4 and H loci; (2) the use of such markers to facilitate the positional cloning of these loci; (3) the recovery of additional radiation- or transposon-induced revertants of M or H activity; (4) embryo injection of M- or H-containing BACs, or germline transformation with cloned M or H factors, either to rescue lethal phenotypes or to confer M or H activity on wild-type recipients.