title: Modelling the correlation between the activities of adjacent genes in Drosophila.
abstract: BACKGROUND
  Correlation between the expression levels of genes which are located close to each other on the genome has been found in various organisms, including yeast, drosophila and humans. Since such a correlation could be explained by several biochemical, evolutionary, genetic and technological factors, there is a need for statistical models that correspond to specific biological models for the correlation structure.
  
  
  RESULTS
  We modelled the pairwise correlation between the expressions of the genes in a Drosophila microarray experiment as a normal mixture under Fisher's z-transform, and fitted the model to the correlations of expressions of adjacent as well as non-adjacent genes. We also analyzed simulated data for comparison. The model provided a good fit to the data. Further, correlation between the activities of two genes could, in most cases, be attributed to either of two factors: the two genes both being active in the same age group (adult or embryo), or the two genes being in proximity of each other on the chromosome. The interaction between these two factors was weak.
  
  
  CONCLUSIONS
  Correlation between the activities of adjacent genes is higher than between non-adjacent genes. In the data we analyzed, this appeared, for the most part, to be a constant effect that applied to all pairs of adjacent genes.
authors.affiliation: Clinical Epidemiology and Biostatistics, Academisch Medisch Centrum, University of Amsterdam, Meibergdreef 9, 1100 DD Amsterdam, Netherlands. h.h.thygesen@amc.uva.nl
authors.forename: Helene H
authors.initials: HH
authors.lastname: Thygesen
authors.forename: Aeilko H
authors.initials: AH
authors.lastname: Zwinderman
mesh_terms: D000465:Algorithms; D000818:Animals; D017173:Caenorhabditis elegans; D002843:Chromatin / Q000737:chemistry; D002874:Chromosome Mapping; D002875:Chromosomes; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods*; D003198:Computer Simulation; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D014644:Genetic Variation; D016678:Genome; D023281:Genomics; D008954:Models, Biological; D008957:Models, Genetic; D015233:Models, Statistical; D020411:Oligonucleotide Array Sequence Analysis; D012984:Software
chemical_list: D002843:Chromatin