Date of Award


Document Type

Honors Thesis (Colby Access Only)


Colby College. Biology Dept.


Joshua Kavaler

Second Advisor

Tariq Ahmad

Third Advisor

Russell Johnson


Sensory organ differentiation is a complex process known to be developmentally regulated by transcription factor networks. One such factor is D-Pax2, known to be necessary for proper bristle differentiation in Drosophila melanogaster. The expression pattern of D-Pax2 reveals that it is regulated spatially and temporally, yet how such precise regulation is done is unknown. To determine how D-Pax2 is regulated we created multiple sets of reporter constructs bearing pieces of the presumptive bristle specific enhancer of D-Pax2 coupled to GFP. We proposed that proneural genes of the achaete-scute complex, known to be necessary for sensory organ specification, were regulating D-Pax2 through four E-box sites that were found at most 1.6 kb from the transcription start site. Reporter constructs bearing the enhancer with E-box sites mutated did not show reporter gene expression suggesting the necessity of these sites in normal D-Pax2 activation. Further experiments in which ectopic expression of the proneural gene scute caused reporter gene expression to follow support our hypothesis that proneural genes act upstream of D-Pax2. By cloning D-Pax2 enhancer fragments of varying size, we were also able to determine that later D-Pax2 expression is controlled by an unknown element lying between 2 and 3kb upstream of the transcription start site. This element appears to be controlled independently of the early proneural enhancer and in an autoregulatory manner where D-Pax2 either directly or indirectly activates its own transcription. Our evidence thus indicates that D-Pax2 is controlled temporally through two separate enhancers; the proximal proneural enhancer controlling early expression and the distal autoregulatory enhancer controlling later expression


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D-Pax2, Drosophila, Bristle Differentiation, scute, E-box, Proneural Genes