Gfat1/zeppelin is an essential heterochromatic gene involved in cuticle formation in D. melanogaster

Many essential genes exist in heterochomatin despite the high composition of repeat or ‘junk’ DNA in these regions. The gene zeppelin (zep) was genetically mapped to a distal segment of 3R heterochromatin by the Bejsovec lab. As well as being essential, it is characterised by an abnormal expansion of the embryo cuticle, a ‘blimp’ phenotype. Gfat1 is part of the hexosamine pathway that uses glucose to form chitin, a major component of the exoskeleton and therefore a candidate for causing the ‘blimp’ phenotype. Using genetic and molecular approaches, I have determined that the zep gene coincides with Gfat1 and further alleles have also been identified and characterized. Inter se complementation has revealed an interesting semi-viable Splayed (Spl) phenotype, characterised by weak legs and melanotic deposits at leg joints. Reproduction of the Spl phenotype via RNAi has further confirmed the correspondence of the zeppelin locus with Gfat1