(The Dirtiest Molecular Biologist)
The molecular basis of diversity in the shapes of organisms is one of the most fascinating themes in evolutionary developmental biology. The horned beetle (genus Onthophagus) provides excellent opportunities to study this fundamental question due to dramatic diversity in horn location (expressed on either the head or prothorax, or both), number, size, and shape. The horn expression pattern differs across species, between sexes, and even within a sex (see two male morphs of O. taurus below). These three types of differences (between species, between sexes, and within a sex) further raise an important question: how conserved (or diversified) are the molecular mechanisms across these three types of differences?
My first approach is to find genes or gene networks that are responsible for the horn development. We use both high-throughput (next-gen sequencing and microarrays) and target gene approaches in order to identify promising candidates. To elucidate the effect of specific genes on horn development, I perform functional studies using larval RNAi. I further characterize the gene function using targeted expression analyses (in situ hybridizations and quantitative PCR) to validate the location, timing, and magnitude of gene expression. These studies will reveal the molecular mechanisms underlying the differences between species, sexes, and morphs. I also hope to observe the behavior of beetles whose horn development is altered by RNAi.
From left to right: lateral view of O. taurus large male, small male, and female. Horns are expressed only on the posterior head of males, showing significant size difference.
Lateral view of O. sagittarius male (left) and female (right). Here, horns are expressed in both sexes. Note that horn number and position is different between the sexes.
TK (middle) is having fun with the colleagues during beetle food (aka cow manure) collecting. I am proudly “the dirtiest molecular biologist in the world”. Those who claim the title are welcomed to contact me (tkijimot(at sign)indiana(dot)edu). Photo by Franck Simonnet.