Screen for Enhancers of Mutant Dorsal Vessel Phenotypes and Transcription Factors Expressed in the Dorsal Vessel of Drosophila

Proper heart development in vertebrates is of vital importance to the life of the organism. The analogous structure in Drosophila, the dorsal vessel, is frequently used as a model for the early development of the vertebrate heart as it maintains a similar structure and both are specified through conserved pathways.

I have performed a sensitized screen of the second chromosome in Drosophila using a mutant allele of the tinman gene, tin305, a homeobox-containing transcription factor required for early dorsal vessel development, and second chromosome deficiency regions obtained from Bloomington Stock Center. The purpose of this screen is to isolate regions of the second chromosome that contain genes that enhance the effect of tin305 in dorsal vessel development and therefore interact with tin in dorsal vessel development. Additionally, regions showing an increase in mutant dorsal vessel phenotypes have been further screened in an effort to isolate genes within the region that play a novel role in dorsal vessel development.

A second screen for transcription factors expressed in the dorsal vessel has also been conducted. In this screen, enhancer-GAL4 fly lines are crossed with a UAS-dsRed reporter, using the methodology of Brand and Perrimon (1993), which reveals the expression pattern of each enhancer. Five genes showing interesting expression patterns have been isolated using this methodology. One gene in particular, cap-n-collar (cnc), was found to be expressed in the cardioblasts during late embryonic and first instar developmental time points. Phenotypic analysis of cnc indicates that it may play a role in organization of the cardioblasts during development.