Cell behaviour of Drosophila fat cadherin mutations in wing development

We have studied several cell behaviour parameters of mutant alleles of fat (fr) in Drosophila imaginal wing disc development. Mutant imaginal discs co ntinue growing in larvae delayed in pupariation and can reach sizes of seve ral times those of wild-type. Their growth is, however, basically allometri c. Homozygous ft cells grow faster than their twin cells in clones and gene rate larger territories, albeit delimited by normal clonal restrictions. Mo reover,ft cells in clones tend to grow towards wing proximal regions. These behaviours can be related with failures in cell adhesiveness and cell reco gnition. Double mutant combinations with alleles of other genes, e.g. of th e Epidermal growth factor receptor (DER) pathway, modify ft clonal phenotyp es, indicating that adhesiveness is modulated by intercellular signalling. Mutant ft cells show, in addition, smaller cell sizes during proliferation and abnormal cuticular differentiation, which reflect cell membrane and cyt oskeleton anomalies, which are not modulated by the DER pathway. (C) 2000 E lsevier Science Ireland Ltd. All rights reserved.