MOLECULAR CHARACTERIZATION OF THE 71E LATE PUFF IN DROSOPHILA-MELANOGASTER REVEALS A FAMILY OF NOVEL GENES

Early metamorphic development in Drosophila melanogaster is initiated by pulses of the steroid hormone ecdysone, which are transduced into t issue-specific transcriptional cascades. This process begins with the hormone-dependent activation of a set of transcription factors (early genes) that, in turn, activate set of tissue-specific effector genes ( late genes). The 71E cytogenetic region of the salivary gland polytene genome contains several ecdysone-regulated transcription units. Molec ular techniques were used to analyze these genes, their transcriptiona l program and their evolutionary relatedness. We find that this region contains a cluster of ten coordinately regulated late genes (L71 gene s) that are organized as five divergently transcribed gene pairs. Maxi mum parsimony analysis suggests that an ancestral L71 gene duplicated to form the first gene pair which was, in turn, duplicated to form the set of gene pairs. The L71 gene products form a family of small, chem ically basic proteins with a conserved backbone of cysteine residues. In addition, the 71E region contains another gene (I71-1) with the reg ulatory and biochemical characteristics of the salivary gland intermol t glue proteins. (C) 1996 Academic Press Limited