Towards the genetic dissection of mitosis in <i>Drosophila</i>

Ripóll, Pedro; Casal, José; González, Cayetano

doi:10.1002/bies.950070504

Cited by 16 publications

(6 citation statements)

References 35 publications

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“…Examination of cell division in mutant larval brains would therefore reveal potential mitotic defects. This strategy has been used with considerable success to identify a variety of mitotic mutations in Drosophila (reviewed by Ripoll et al, 1987;Glover, 1989;Gatti and Goldberg, 1991).…”

Section: Identification Of the Twinstar Locusmentioning

confidence: 99%

Mutations in twinstar, a Drosophila gene encoding a cofilin/ADF homologue, result in defects in centrosome migration and cytokinesis.

Gunsalus

Bonaccorsi

Williams

et al. 1995

The Journal of Cell Biology

284

282

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Abstract. We describe the phenotypic and molecular characterization of twinstar (tsr), an essential gene in Drosophila melanogaster. Two P-element induced alleles of tsr (tsr l and tsr 2) result in late larval or pupal lethality. Cytological examination of actively dividing tissues in these mutants reveals defects in cytokinesis in both mitotic (larval neuroblast) and meiotic (larval testis) cells. In addition, mutant spermatocytes show defects in aster migration and separation during prophase/prometaphase of both meiotic divisions. We have cloned the gene affected by these mutations and shown that it codes for a 17-kD protein in the cofilin/ ADF family of small actin severing proteins. A cDNA for this gene has previously been described by Edwards et al. (1994). Northern analysis shows that the tsr gene is expressed throughout development, and that the tsr a and tsr 2 alleles are hypomorphs that accumulate decreased levels of tsr mRNA. These findings prompted us to examine actin behavior during male meiosis to visualize the effects of decreased twinstar protein activity on actin dynamics in vivo. Strikingly, both mutants exhibit abnormal accumulations of F-actin. Large actin aggregates are seen in association with centrosomes in mature primary spermatocytes. Later, during ana/telophase of both meiotic divisions, aberrantly large and misshaped structures appear at the site of contractile ring formation and fail to disassemble at the end of telophase, in contrast with wild-type. We discuss these resuits in terms of possible roles of the actin-based cytoskeleton in centrosome movement and in cytokinesis.ECULATED interactions between actin and actin binding proteins provide an important structural basis for many cellular processes in eukaryotes, such as cell-cell adhesion, cell outgrowth and motility, muscle contraction, and cytokinesis. Changes in the intracellular localization and organization of actin are mediated by a repertoire of actin-associated proteins. These fall into several classes based on their effects on actin assembly and dynamics in vitro: proteins with cross-linking, bundling, capping, severing, polymerizing/depolymerizing, monomer sequestering, and motor activities have been described (reviewed by Vandekerckove and Vancompernalle, 1992). However, defining the role that each actin-associated protein plays in vivo and how multiple activities are coordinated remains a challenging task.Proteins in the cofilin/actin depolymerizing factor (ADF) 1 family have been identified in a wide range of eukaryotic organisms, from yeast to plants to humans. These small molecular mass (15-20 kD) actin binding proteins consti-

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Section: Identification Of the Twinstar Locusmentioning

confidence: 99%

Mutations in twinstar, a Drosophila gene encoding a cofilin/ADF homologue, result in defects in centrosome migration and cytokinesis.

Gunsalus

Bonaccorsi

Williams

et al. 1995

The Journal of Cell Biology

284

282

View full text Add to dashboard Cite

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“…This reasoning has prompted the search for genes affecting cell-cycle events among collec tions of larval and pupal lethal mutations (Ripoll et al 1987;Gatti & Baker 1989; Glover 1989) and may be applicable to genes controlling early cytoskeletal functions. For example, the locus spaghetti-squash was initially discovered since mutations result in late zygotic lethality because of faulty cytokinesis.…”

Section: Genetic Approachesmentioning

confidence: 99%

Functional Elements of the Cytoskeleton in the Early Drosophila Embryo

Schejter

Wieschaus²

1993

Annu. Rev. Cell. Biol.

146

123

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“…A final group of mutations affecting mitosis have been recognised that result in lethality in either late larval or early pupal development (Gatti et al 1983;Ripoll et al 1987;Gatti and Baker, 1989). The mitotic phenotype is not generally manifest until these stages, since the homozygous mutant zygote is supplied with sufficient wild-type gene product from its heterozygous mother for embryogenesis.…”

Section: Introductionmentioning

confidence: 99%

Mutations at the ASP locus of Drosophila lead to multiple free centrosomes in syncytial embryos, but restrict centrosome duplication in larval neuroblasts

González

Saunders

Casal

et al. 1990

Journal of Cell Science

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Mutations at abnormal spindle result in abnormally long and wavy microtubules in the meiotic spindles of males. Some of these spindles have a single pole and take the form of unopposed hemi-spindles. Unfertilised eggs produced by homozygous asp females may have either no nuclei, or a small number of large nuclei, consistent with there also being an effect upon female meiosis. Such eggs also display free centrosomes and independent arrays of microtubules. Embryos that have this phenotype are also present among the progeny of fertilised homozygous asp females, together with embryos that undergo varying degrees of aberrant morphogenesis, developing a variety of abnormal cuticle patterns. This latter category shows asynchronous mitoses prior to cellularisation, and has abnormal arrays of spindle microtubules. Such embryos can develop large areas that are either devoid of or have a reduced number of nuclei, in which there are centrosomes that have dissociated from the mitotic spindles. Neuroblasts in the brains of homozygous asp larvae display a high mitotic index, and have condensed chromosomes aligned as if blocked at metaphase. Immunostaining reveals that many cells contain a single centrosome connected to the metaphase chromosomes by microtubules in a hemi-spindle-like structure.

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Towards the genetic dissection of mitosis in Drosophila

Cited by 16 publications

References 35 publications

Mutations in twinstar, a Drosophila gene encoding a cofilin/ADF homologue, result in defects in centrosome migration and cytokinesis.

Mutations in twinstar, a Drosophila gene encoding a cofilin/ADF homologue, result in defects in centrosome migration and cytokinesis.

Functional Elements of the Cytoskeleton in the Early Drosophila Embryo

Mutations at the ASP locus of Drosophila lead to multiple free centrosomes in syncytial embryos, but restrict centrosome duplication in larval neuroblasts

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