ORIGINAL ARTICLE

Development Genes and Evolution

, Volume 206, Issue 8, pp 481-493

First online:

Developing compound eye in lozenge mutants of Drosophila: lozenge expression in the R7 equivalence group

  • J. R. CrewAffiliated withDepartment of Biological Sciences & National Science Foundation Center for Light Microscope Imaging and Biotechnology, Carnegie Mellon University, Pittsburgh, PA 15213, USA
  • , Philip BatterhamAffiliated withUniversity of Melbourne, Parkville, Victoria 3052, Australia
  • , J. A. PollockAffiliated withDepartment of Biological Sciences & National Science Foundation Center for Light Microscope Imaging and Biotechnology, Carnegie Mellon University, Pittsburgh, PA 15213, USA

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

 The lozenge locus is genetically complex, containing two functionally distinct units, cistrons A and B, that influence the structure of the compound eye. Extreme mutations of either cistron produce adult phenotypes that share similarities and that have striking differences. We have analyzed the expression of several developmentally important eye genes including boss, scabrous, rhomboid, seven-up, and Bar in lozenge mutant backgrounds representing both cistrons. This analysis follows the progressive recruitment of photoreceptor neurons during eye development and has confirmed that the initial development of photoreceptors is normal up to the five cell precluster stage (R8, R2/5 and R3/4). However, when lozenge is mutant, further eye development is perturbed. As cells R1, R6 and R7 are recruited, patterns of gene expression for seven-up and Bar become abnormal. We have also characterized the expression of two different enhancer trap alleles of lozenge. The lozenge product(s) appear to be first expressed in the eye disc in undifferentiated cells shortly after the five cell precluster forms. Then, as distinct cells are recruited to a fate, lozenge expression persists and is refined in those cells. Our data suggests that lozenge functions in cone cells and pigment cells as well as in specific glia. With respect to photoreceptor neurons, lozenge biases the developmental potential of cells R1, R6 and R7, by directly influencing the expression of genes important for establishing cell fate.

Key words Seven up Bar Photoreceptor cells Cone cells Pigment cells