Characterization of () and , Essential Paralogous Genes Which Encode the Enzymes That Catalyze the Rate-Limiting Step in the Hexosamine Biosynthetic Pathway in .

The () locus is known for its essential role in the development of the embryonic cuticle of . We show here that encodes (; ), the enzyme that catalyzes the rate-limiting step in the hexosamine biosynthesis pathway (HBP). This conserved pathway diverts 2%-5% of cellular glucose from glycolysis and is a nexus of sugar (fructose-6-phosphate), amino acid (glutamine), fatty acid [acetyl-coenzymeA (CoA)], and nucleotide/energy (UDP) metabolism.

Genetic and Molecular Analysis of Essential Genes in Centromeric Heterochromatin of the Left Arm of Chromosome 3 in .

A large portion of the genome is contained within heterochromatic regions of chromosomes, predominantly at centromeres and telomeres. The remaining euchromatic portions of the genome have been extensively characterized with respect to gene organization, function and regulation. However, it has been difficult to derive similar data for sequences within centromeric (centric) heterochromatin because these regions have not been as amenable to analysis by standard genetic and molecular tools.

dSet1 is the main H3K4 di- and tri-methyltransferase throughout Drosophila development.

In eukaryotes, the post-translational addition of methyl groups to histone H3 lysine 4 (H3K4) plays key roles in maintenance and establishment of appropriate gene expression patterns and chromatin states. We report here that an essential locus within chromosome 3L centric heterochromatin encodes the previously uncharacterized Drosophila melanogaster ortholog (dSet1, CG40351) of the Set1 H3K4 histone methyltransferase (HMT). Our results suggest that dSet1 acts as a "global" or general H3K4 di- and trimethyl HMT in Drosophila.