scholarly journals Drosophila Centrosomin Protein is Required for Male Meiosis and Assembly of the Flagellar Axoneme

1998 ◽  
Vol 141 (2) ◽  
pp. 455-467 ◽  
Author(s):  
Kaijun Li ◽  
Eugene Yujun Xu ◽  
Jeffrey K. Cecil ◽  
F. Rudolf Turner ◽  
Timothy L. Megraw ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Basal Body ◽  
Mutational Analysis ◽  
Male Meiosis ◽  
Mitosis And Meiosis ◽  
Flagellar Axoneme

Centrosomes and microtubules play crucial roles during cell division and differentiation. Spermatogenesis is a useful system for studying centrosomal function since it involves both mitosis and meiosis, and also transformation of the centriole into the sperm basal body. Centrosomin is a protein localized to the mitotic centrosomes in Drosophila melanogaster. We have found a novel isoform of centrosomin expressed during spermatogenesis. Additionally, an anticentrosomin antibody labels both the mitotic and meiotic centrosomes as well as the basal body. Mutational analysis shows that centrosomin is required for spindle organization during meiosis and for organization of the sperm axoneme. These results suggest that centrosomin is a necessary component of the meiotic centrosomes and the spermatid basal body.

scholarly journals The Drosophila Kinesin-like Protein KLP67A Is Essential for Mitotic and Male Meiotic Spindle Assembly

2004 ◽  
Vol 15 (1) ◽  
pp. 121-131 ◽  
Author(s):  
Rita Gandhi ◽  
Silvia Bonaccorsi ◽  
Diana Wentworth ◽  
Stephen Doxsey ◽  
Maurizio Gatti ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Spindle Assembly ◽  
Male Meiosis ◽  
Meiotic Spindle ◽  
Drosophila Cell ◽  
Centrosome Separation ◽  
Mutant Cells

We have performed a mutational analysis together with RNA interference to determine the role of the kinesin-like protein KLP67A in Drosophila cell division. During both mitosis and male meiosis, Klp67A mutations cause an increase in MT length and disrupt discrete aspects of spindle assembly, as well as cytokinesis. Mutant cells exhibit greatly enlarged metaphase spindle as a result of excessive MT polymerization. The analysis of both living and fixed cells also shows perturbations in centrosome separation, chromosome segregation, and central spindle assembly. These data demonstrate that the MT plus end-directed motor KLP67A is essential for spindle assembly during mitosis and male meiosis and suggest that the regulation of MT plus-end polymerization is a key determinant of spindle architecture throughout cell division.

scholarly journals Mutational Analysis of a Histone Deacetylase in Drosophila melanogaster: Missense Mutations Suppress Gene Silencing Associated With Position Effect Variegation

Genetics ◽  
2000 ◽  
Vol 154 (2) ◽  
pp. 657-668 ◽  
Author(s):  
Randy Mottus ◽  
Richard E Sobel ◽  
Thomas A Grigliatti
Keyword(s):  
Drosophila Melanogaster ◽  
Histone Deacetylase ◽  
Transcriptional Activity ◽  
Mutational Analysis ◽  
Position Effect ◽  
Transcriptional Regulator ◽  
Position Effect Variegation ◽  
Missense Mutations ◽  
Effect Variegation ◽  
New Mutations

Abstract For many years it has been noted that there is a correlation between acetylation of histones and an increase in transcriptional activity. One prediction, based on this correlation, is that hypomorphic or null mutations in histone deacetylase genes should lead to increased levels of histone acetylation and result in increased levels of transcription. It was therefore surprising when it was reported, in both yeast and fruit flies, that mutations that reduced or eliminated a histone deacetylase resulted in transcriptional silencing of genes subject to telomeric and heterochromatic position effect variegation (PEV). Here we report the first mutational analysis of a histone deacetylase in a multicellular eukaryote by examining six new mutations in HDAC1 of Drosophila melanogaster. We observed a suite of phenotypes accompanying the mutations consistent with the notion that HDAC1 acts as a global transcriptional regulator. However, in contrast to recent findings, here we report that specific missense mutations in the structural gene of HDAC1 suppress the silencing of genes subject to PEV. We propose that the missense mutations reported here are acting as antimorphic mutations that “poison” the deacetylase complex and propose a model that accounts for the various phenotypes associated with lesions in the deacetylase locus.

scholarly journals MUTATIONAL ANALYSIS OF THE REGION SURROUNDING THE 93D HEAT SHOCK LOCUS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1984 ◽  
Vol 106 (2) ◽  
pp. 249-265
Author(s):  
Jym Mohler ◽  
Mary Lou Pardue
Keyword(s):  
Drosophila Melanogaster ◽  
Heat Shock ◽  
Mutational Analysis ◽  
Point Mutations ◽  
Γ Irradiation ◽  
Lethal Mutations ◽  
Complementation Groups ◽  
In Trans ◽  
Shock Locus ◽  
Shock Proteins

ABSTRACT The region containing subdivisions 93C, 93D and 93E on chromosome 3 of Drosophila melanogaster has been screened for visible and lethal mutations. Treatment with three mutagens, γ irradiation, ethyl methanesulfonate and diepoxybutane, has produced mutations that fall into 20 complementation groups, including the previously identified ebony locus. No point mutations affecting the heat shock locus in 93D were detected; however, a pair of deficiencies that overlap in the region of this locus was isolated. Flies heterozygous in trans for this pair of deficiencies are capable of producing all of the major heat shock puffs (except 93D) and the major heat shock proteins. In addition, these flies show recovery of normal protein synthesis following a heat shock.

fumble Encodes a Pantothenate Kinase Homolog Required for Proper Mitosis and Meiosis in Drosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1267-1276
Author(s):  
Katayoun Afshar ◽  
Pierre Gönczy ◽  
Stephen DiNardo ◽  
Steven A Wasserman
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Cell Division Cycle ◽  
Protein Isoforms ◽  
Pantothenate Kinase ◽  
Male Germline ◽  
Dividing Cells ◽  
Mutant Cells ◽  
Mitosis And Meiosis

Abstract A number of fundamental processes comprise the cell division cycle, including spindle formation, chromosome segregation, and cytokinesis. Our current understanding of these processes has benefited from the isolation and analysis of mutants, with the meiotic divisions in the male germline of Drosophila being particularly well suited to the identification of the required genes. We show here that the fumble (fbl) gene is required for cell division in Drosophila. We find that dividing cells in fbl-deficient testes exhibit abnormalities in bipolar spindle organization, chromosome segregation, and contractile ring formation. Cytological analysis of larval neuroblasts from null mutants reveals a reduced mitotic index and the presence of polyploid cells. Molecular analysis demonstrates that fbl encodes three protein isoforms, all of which contain a domain with high similarity to the pantothenate kinases of A. nidulans and mouse. The largest Fumble isoform is dispersed in the cytoplasm during interphase, concentrates around the spindle at metaphase, and localizes to the spindle midbody at telophase. During early embryonic development, the protein localizes to areas of membrane deposition and/or rearrangement, such as the metaphase and cellularization furrows. Given the role of pantothenate kinase in production of Coenzyme A and in phospholipid biosynthesis, this pattern of localization is suggestive of a role for fbl in membrane synthesis. We propose that abnormalities in synthesis and redistribution of membranous structures during the cell division cycle underlie the cell division defects in fbl mutant cells.

scholarly journals Functional monopolar spindles caused by mutation in mgr, a cell division gene of Drosophila melanogaster

1988 ◽  
Vol 89 (1) ◽  
pp. 39-47 ◽  
Author(s):  
C. Gonzalez ◽  
J. Casal ◽  
P. Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Genetic Analysis ◽  
Normal Chromosome ◽  
Phenotypic Traits ◽  
Polyploid Cells ◽  
A Cell

Mutation in the gene merry-go-round (mgr) of Drosophila causes a variety of phenotypic traits in somatic and germinal tissues, such as polyploid cells, metaphasic arrest, postmeiotic cysts with 16 nuclei, and spermatids with four times the normal chromosome content. The most characteristic phenotype is the appearance of mitotic and meiotic figures where all chromosomes are arranged in a circle. Treatment with anti-mitotic drugs and the phenotype of double mutants mgr asp (asp being a mutation altering the spindle) show that these circular figures need a functional spindle for their formation. These abnormal figures are caused by monopolar spindles similar to those observed after different treatments in several organisms. All mutant traits indicate that mgr performs a function necessary for the correct behaviour of centrosomes, thus opening this organelle to genetic analysis.

scholarly journals The ultrastructure of cell division in Euglena gracilis

1978 ◽  
Vol 31 (1) ◽  
pp. 25-35
Author(s):  
M.A. Gillott ◽  
R.E. Triemer
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Basal Body ◽  
Euglena Gracilis ◽  
Equatorial Region ◽  
Basal Bodies ◽  
Cleavage Furrow ◽  
Free Zone ◽  
Prophase Nucleus

The ultrastructure of mitosis in Euglena gracilis was investigated. At preprophase the nucleus migrates anteriorly and associates with the basal bodies. Flagella and basal bodies replicate at preprophase. Cells retain motility throughout division. The reservoir and the prophase nucleus elongate perpendicular to the incipient cleavage furrow. One basal body pair surrounded by a ribosome-free zone is found at each of the nuclear poles. The spindle forms within the intact nuclear envelope- Polar fenestrae are absent. At metaphase, the endosome is elongated from pole to pole, and chromosomes are loosely arranged in the equatorial region. Distinct, trilayered kinetochores are present. Spindle elongates as chromosomes migrate to the poles forming a dumb-bell shaped nucleus by telophase. Daughter nuclei are formed by constriction of the nuclear envelope. Cytokinesis is accomplished by furrowing. Cell division in Euglena is compared with that of certain other algae.

Dosage dependence of maternal contribution to somatic cell division in Drosophila melanogaster

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
M. Carmena ◽  
C. Gonzalez ◽  
J. Casal ◽  
P. Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Somatic Cell ◽  
Early Development ◽  
Normal Cell ◽  
Chromosome Behaviour ◽  
Wild Type ◽  
Maternal Contribution ◽  
Different Doses ◽  
Chromosome Nondisjunction

Most mitotic mutants in Drosophila do not lead to lethality in early development despite the highly abnormal chromosome behaviour that they elicit. This has been explained as being the effect of maternally provided wild-type products. We have tested this hypothesis by studying cuticular clones derived from cells in which there has been loss of a marked Y chromosome due to chromosome nondisjunction in individuals homozygous for the mutation abnormal spindle who are progeny of heterozygous mothers. We have found that the size and frequency of these clones are higher than in control flies. Furthermore, by analysing flies whose female parents have different doses of the asp+ gene, we have found that there is a correlation between the amount of maternally contributed asp+ product and the frequency and size of cuticular clones. We have also estimated the time in development when the first mitotic mistakes take place, i.e. the time when maternal products are no longer sufficient to carry out normal cell division.

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