Mutations in a novel gene, ida, cause prepupal lethality and defects in chromosome condensation and mitosis.ida. A.M. Bentley ¹, B.C. Williams ², M.L. Goldberg ², A.J. Andres ¹. 1) Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, IL; 2) Section of Genetics and Development, Cornell University, Ithaca, New York.

   At metamorphosis, Drosophila will undergo a dramatic reorganization of their body plan. This reorganization is in part made possible by the specification of cells into either a larval or adult fate at early embryogenesis. We have cloned and characterized a gene we call ida (imaginal discs arrested) that is required for viability during metamorphosis and proliferation of the adult fated imaginal disc cells. ida mutant animals are lacking all differentiated imaginal disc structures and have smaller than normal optic lobes, suggesting a mitotic defect. Orcein squashes show that mutations in ida do not block entry into mitosis, but rather prevent chromosomes from properly condensing and reaching the metaphase plate. We have also shown that a maternal component is required for events during egg production. ida encodes a novel protein that includes a bipartite nuclear localization sequence (NLS) and putative PKA and PKC phosphorylation sites which are lost in a one null allele. We propose a model in which a post-transitionally modified Ida protein is an essential factor in cell cycle progression.idaDrosophila.