From genes to behavior

M. FERNANDA CERIANI

Tallin, Estonia

Workshop; 2004 Meeting of the HHMI International Research Scholars.; 2004

In Drosophila a number of key processes such as emergence from the pupal case, locomotor activity, olfaction, feeding, and aspects of mating behavior are under circadian regulation.  Specifically we are interested in unraveling the molecular mechanisms underlying the circadian control of rest/activity cycles.  To that end we have explored two complementary strategies, a forward genetic screen based on the yeast GAL4/UAS system, and an oligonucleotide-based high-density array that interrogates gene expression changes on a whole genome level. The genetic screen relies on the induction of the expression of genes tagged by the insertion of a P-element which carries a GAL4-controlled promoter oriented so that it transcribes flanking genomic sequences, therefore most likely generating gain of function mutations.  These ‘target lines’ are then crossed to a ‘pattern line’, which expresses GAL4 under the control of a specific promoter.  Over 600 novel insertion lines have been generated and have been monitored for defects on rhythmic behavior using an automated locomotor activity setup.  So far we identified both, short and long period together with arrythmic mutants.  Plasmid rescue analysis allowed the identification of the target genes.  Among those we found previously known genes never associated with clock function as well as novel genes.  In parallel we analyzed the extent of clock-controlled transcription over a two-day timecourse.  Among the cycling genes we identified and characterized a cyclic potassium channel protein as a key step in linking the transcriptional feedback loop to overt behavior.