Sex Determination Genes Intersex and Transformer-2’s Role in the Development of Onthophagus taurus Horns

Sydney Friend,*and Teyia Kijimoto, Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV 26506

Field (Broad Category): Biology (Agricultural & Environmental Sciences) 

Student’s Major: Animal and Nutritional Sciences 

The mechanisms in which dimorphism occurs has not been fully understood despite its significance in ecological diversification. This study utilized the development of sexually dimorphic traits in the dung beetle species Onthophagus taurus. In O. taurus, the gene doublesex (dsx) regulates sexual dimorphisms by promoting trait development in males and inhibiting it in females. Particularly, just like other beetles, their horns play an important ecological role in males(i.e competition for females) therefore this species is used as a model to study the genetic underpinnings of horn development. The focus of this study is on genes intersex(ix) and transformer-2 (tra2) and their significance in the development of O. taurus horns in relation to dsx. Tra-2 is assumed to be a regulator of the sex-specific splicing of dsx pre-mRNA in female Drosphilia(fruit flies) while remaining inactive in males. Ix in Drosphilia is proposed to be a transcriptional cofactor of doublesex but like tra-2 it is inactive in male flies. The interactions of ix and tra-2 in regard to the developmental pathway of beetles and their horns are not presently known. To address this question, systematic knockdowns of ix and tra-2 will be implemented to observe developmental changes in male and female beetles.If similar to the interactions found in flies it is expected that by repressing ix and tra-2, horn development will not be affected in males. Females;however,may have their pathway altered in a way that they will develop male traits such as horns. We will present current data and discuss their significance. 

Funding: WVU 

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course