title: Quantitative analysis of bristle number in Drosophila mutants identifies genes involved in neural development.
abstract: BACKGROUND
  The identification of the function of all genes that contribute to specific biological processes and complex traits is one of the major challenges in the postgenomic era. One approach is to employ forward genetic screens in genetically tractable model organisms. In Drosophila melanogaster, P element-mediated insertional mutagenesis is a versatile tool for the dissection of molecular pathways, and there is an ongoing effort to tag every gene with a P element insertion. However, the vast majority of P element insertion lines are viable and fertile as homozygotes and do not exhibit obvious phenotypic defects, perhaps because of the tendency for P elements to insert 5' of transcription units. Quantitative genetic analysis of subtle effects of P element mutations that have been induced in an isogenic background may be a highly efficient method for functional genome annotation.
  
  
  RESULTS
  Here, we have tested the efficacy of this strategy by assessing the extent to which screening for quantitative effects of P elements on sensory bristle number can identify genes affecting neural development. We find that such quantitative screens uncover an unusually large number of genes that are known to function in neural development, as well as genes with yet uncharacterized effects on neural development, and novel loci.
  
  
  CONCLUSIONS
  Our findings establish the use of quantitative trait analysis for functional genome annotation through forward genetics. Similar analyses of quantitative effects of P element insertions will facilitate our understanding of the genes affecting many other complex traits in Drosophila.
authors.affiliation: Howard Hughes Medical Institute, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room T630, Houston, TX 77030, USA.
authors.forename: Koenraad K
authors.initials: KK
authors.lastname: Norga
authors.forename: Marjorie C
authors.initials: MC
authors.lastname: Gurganus
authors.forename: Christy L
authors.initials: CL
authors.lastname: Dilda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Richard F
authors.initials: RF
authors.lastname: Lyman
authors.forename: Prajal H
authors.initials: PH
authors.lastname: Patel
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Rubin
authors.forename: Roger A
authors.initials: RA
authors.lastname: Hoskins
authors.forename: Trudy F
authors.initials: TF
authors.lastname: Mackay
authors.forename: Hugo J
authors.initials: HJ
authors.lastname: Bellen
mesh_terms: D000818:Animals; D004330:Drosophila / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D009154:Mutation; D010525:Peripheral Nerves / Q000254:growth & development