The Ketel^D Dominant-Negative Mutations Identify Maternal Function of the Drosophila Importin-ß Gene Required for Cleavage Nuclei Formation

Corresponding author: János Szabad, Faculty of General Medicine, Department of Biology, University of Szeged, H-6720 Szeged, Somogyi B. u. 4, Hungary., szabad{at}comser.szote.u-szeged.hu (E-mail)

Communicating editor: T. C. KAUFMAN

The Ketel^D dominant female-sterile mutations and their ketel^r revertant alleles identify the Ketel gene, which encodes the importin-ß (karyopherin-ß) homologue of Drosophila melanogaster. Embryogenesis does not commence in the Ketel^D eggs deposited by the Ketel^D/+ females due to failure of cleavage nuclei formation. When injected into wild-type cleavage embryos, cytoplasm of the Ketel^D eggs does not inhibit nuclear protein import but prevents cleavage nuclei formation following mitosis. The Ketel⁺ transgenes slightly reduce effects of the Ketel^D mutations. The paternally derived Ketel^D alleles act as recessive zygotic lethal mutations: the Ketel^D/- hemizygotes, like the ketel^r/ketel^r and the ketel^r/- zygotes, perish during second larval instar. The Ketel maternal dowry supports their short life. The Ketel^D-related defects originate most likely following association of the Ketel^D-encoded mutant molecules with a maternally provided partner. As in the Ketel^D eggs, embryogenesis does not commence in eggs of germline chimeras with ketel^r/- germline cells and normal soma, underlining the dominant-negative nature of the Ketel^D mutations. The ketel^r homozygous clones are fully viable in the follicle epithelium in wings and tergites. The Ketel gene is not expressed in most larval tissues, as revealed by the expression pattern of a Ketel promoter-lacZ reporter gene.

This article has been cited by other articles:

				Z. Venkei, I. Gaspar, G. Toth, and J. Szabad {alpha}4-Tubulin is involved in rapid formation of long microtubules to push apart the daughter centrosomes during earlyx Drosophila embryogenesis J. Cell Sci., August 1, 2006; 119(15): 3238 - 3248. [Abstract] [Full Text] [PDF]

				C. A. Hunter, M. J. Aukerman, H. Sun, M. Fokina, and R. S. Poethig PAUSED Encodes the Arabidopsis Exportin-t Ortholog Plant Physiology, August 1, 2003; 132(4): 2135 - 2143. [Abstract] [Full Text] [PDF]

				K. M. Bollman, M. J. Aukerman, M.-Y. Park, C. Hunter, T. Z. Berardini, and R. S. Poethig HASTY, the Arabidopsis ortholog of exportin 5/MSN5, regulates phase change and morphogenesis Development, April 15, 2003; 130(8): 1493 - 1504. [Abstract] [Full Text] [PDF]

				G. Timinszky, L. Tirian, F. T. Nagy, G. Toth, A. Perczel, Z. Kiss-Laszlo, I. Boros, P. R. Clarke, and J. Szabad The importin-{beta} P446L dominant-negative mutant protein loses RanGTP binding ability and blocks the formation of intact nuclear envelope J. Cell Sci., April 15, 2002; 115(8): 1675 - 1687. [Abstract] [Full Text] [PDF]

				M. Lippai, L. Tirián, I. Boros, J. Mihály, M. Erdélyi, I. Belecz, E. Máthé, J. Pósfai, A. Nagy, A. Udvardy, et al. The Ketel Gene Encodes a Drosophila Homologue of Importin-{beta} Genetics, December 1, 2000; 156(4): 1889 - 1900. [Abstract] [Full Text]