TISSUE-SPECIFIC AND COMPLEX COMPLEMENTATION PATTERNS IN THE PUNCH LOCUS OF DROSOPHILA MELANOGASTER

William J. Mackay ¹, Elaine R. Reynolds ¹, and Janis M. O'Donnell ¹

¹ Department of Biological Sciences, Carnegie-Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213

Mutations in the Punch locus result in loss of GTP cyclohydrolase activity, but all mutations do not affect the enzyme in the same way. There are at least three classes of Punch mutations. One class results in a dominant eye color, recessive lethal phenotype. A second class of mutations also causes a recessive lethal phenotype, but heterozygous mutants have normal eye color. They show loss of GTP cyclohydrolase function in all tissues where activity can be measured. Alleles comprising a third class are recessive eye color mutations that are homozygous viable. Individuals with this third type of mutation show loss of enzyme activity in the eye, but show normal or near-normal activity elsewhere. In order to examine the organization and function of this locus further, we have performed interallelic complementation tests on 25 Punch mutations, monitoring viability and enzyme activity in prepupae and adults. Most allele combinations are lethal. Those that complement do so in ways that are tissue-or stage-specific and unpredictable. Tests of mutants with tissue-specific phenotypes and of individuals mutant for complementing Punch lethal alleles lead us to conclude that Punch is a complex locus, both with respect to its organization and to its products.

This article has been cited by other articles:

				C. D. Funderburk, K. M. Bowling, D. Xu, Z. Huang, and J. M. O'Donnell A typical N-terminal Extensions Confer Novel Regulatory Properties on GTP Cyclohydrolase Isoforms in Drosophila melanogaster J. Biol. Chem., November 3, 2006; 281(44): 33302 - 33312. [Abstract] [Full Text] [PDF]

				E Eldon, S Kooyer, D D'Evelyn, M Duman, P Lawinger, J Botas, and H Bellen The Drosophila 18 wheeler is required for morphogenesis and has striking similarities to Toll Development, January 4, 1994; 120(4): 885 - 899. [Abstract] [PDF]

				P F Lasko and M Ashburner Posterior localization of vasa protein correlates with, but is not sufficient for, pole cell development. Genes & Dev., June 1, 1990; 4(6): 905 - 921. [Abstract] [PDF]