scholarly journals Cell division in Aspergillus

1992 ◽  
Vol 103 (3) ◽  
pp. 599-611 ◽  
Author(s):  
J.H. Doonan
Keyword(s):  
Cell Division ◽  
Aspergillus Nidulans ◽  
Molecular Analysis ◽  
Filamentous Fungus ◽  
Nuclear Division ◽  
Mutational Analysis ◽  
Cytoskeletal Proteins ◽  
Nuclear Movement ◽  
Cellular Analysis

Amenable to sophisticated genetic and molecular analysis, the simple filamentous fungus Aspergillus nidulans has provided some novel insights into the mechanisms and regulation of cell division. Mutational analysis has identified over fifty genes necessary for nuclear division, nuclear movement and cytokinesis. Molecular and cellular analysis of these mutants has led to the discovery of novel components of the cytoskeleton as well as to clarifying the role of established cytoskeletal proteins. Mutations leading to defects in the kinases (i.e. p34cdc2) and phosphatases (i.e. cdc25 and PP1), which are known to regulate mitosis in other eukaryotes, have been identified in Aspergillus. Additional, as yet novel, mitotic regulatory molecules, encoded by the nimA and bimE genes, have also been discovered in Aspergillus.

scholarly journals Mitochondria and nuclei move by different mechanisms in Aspergillus nidulans.

1985 ◽  
Vol 101 (6) ◽  
pp. 2392-2397 ◽  
Author(s):  
B R Oakley ◽  
J E Rinehart
Keyword(s):  
Aspergillus Nidulans ◽  
Filamentous Fungus ◽  
Colony Formation ◽  
Nuclear Division ◽  
Restrictive Temperature ◽  
Nuclear Movement ◽  
Beta Tubulin ◽  
Mitochondrial Movement ◽  
Tubulin Mutations ◽  
Microtubule Function

We have examined the effects of the antimicrotubule agent benomyl and several mutations on nuclear and mitochondrial movement in germlings of the filamentous fungus Aspergillus nidulans. While, as previously reported, benomyl inhibited nuclear division and movement, it did not inhibit mitochondrial movement. To test the effects of benomyl more rigorously, we germinated two benomyl super-sensitive, beta-tubulin mutants at a benomyl concentration 50-100 times greater than that required to inhibit colony formation completely. Again nuclear division and movement were inhibited, but mitochondrial movement was not. We also examined conditionally lethal beta-tubulin mutations that disrupt microtubule function under restrictive conditions. Nuclear division and movement were inhibited but, again, mitochondrial movement was not. Finally we examined the effects of five heat-sensitive mutations that inhibit nuclear movement but not nuclear division at restrictive temperatures. These mutations strongly inhibited nuclear movement at a restrictive temperature but did not inhibit mitochondrial movement. These data demonstrate that the mechanisms of nuclear and mitochondrial movement in Aspergillus nidulans are not identical and suggest that mitochondrial movement does not require functional microtubules.

scholarly journals Regulation of Pathogenic Spore Germination by CgRac1 in the Fungal Plant Pathogen Colletotrichum gloeosporioides

2011 ◽  
Vol 10 (8) ◽  
pp. 1122-1130 ◽  
Author(s):  
Iris Nesher ◽  
Anna Minz ◽  
Leonie Kokkelink ◽  
Paul Tudzynski ◽  
Amir Sharon
Keyword(s):  
Cell Division ◽  
Plant Pathogen ◽  
Germ Tube ◽  
Colletotrichum Gloeosporioides ◽  
Fluorescent Protein ◽  
Nuclear Division ◽  
Simultaneous Formation ◽  
Content Type ◽  
Germ Tubes

ABSTRACT Colletotrichum gloeosporioides is a facultative plant pathogen: it can live as a saprophyte on dead organic matter or as a pathogen on a host plant. Different patterns of conidial germination have been recognized under saprophytic and pathogenic conditions, which also determine later development. Here we describe the role of CgRac1 in regulating pathogenic germination. The hallmark of pathogenic germination is unilateral formation of a single germ tube following the first cell division. However, transgenic strains expressing a constitutively active CgRac1 (CA-CgRac1) displayed simultaneous formation of two germ tubes, with nuclei continuing to divide in both cells after the first cell division. CA-CgRac1 also caused various other abnormalities, including difficulties in establishing and maintaining cell polarity, reduced conidial and hyphal adhesion, and formation of immature appressoria. Consequently, CA-CgRac1 isolates were completely nonpathogenic. Localization studies with cyan fluorescent protein (CFP)-CgRac1 fusion protein showed that the CgRac1 protein is abundant in conidia and in hyphal tips. Although the CFP signal was equally distributed in both cells of a germinating conidium, reactive oxygen species accumulated only in the cell that produced a germ tube, indicating that CgRac1 was active only in the germinating cell. Collectively, our results show that CgRac1 is a major regulator of asymmetric development and that it is involved in the regulation of both morphogenesis and nuclear division. Modification of CgRac1 activity disrupts the morphogenetic program and prevents fungal infection.

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 The Role of Microtubules in Pancreatic Cancer: Therapeutic Progress

2021 ◽  
Vol 11 ◽  
Author(s):  
Mugahed Abdullah Hasan Albahde ◽  
Bulat Abdrakhimov ◽  
Guo-Qi Li ◽  
Xiaohu Zhou ◽  
Dongkai Zhou ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cell Division ◽  
Pancreatic Carcinoma ◽  
Cancer Cells ◽  
Tumor Cells ◽  
Cytoskeletal Proteins ◽  
Late Diagnosis ◽  
Apoptosis Induction ◽  
Microtubule Targeting Agents

Pancreatic cancer has an extremely low prognosis, which is attributable to its high aggressiveness, invasiveness, late diagnosis, and lack of effective therapies. Among all the drugs joining the fight against this type of cancer, microtubule-targeting agents are considered to be the most promising. They inhibit cancer cells although through different mechanisms such as blocking cell division, apoptosis induction, etc. Hereby, we review the functions of microtubule cytoskeletal proteins in tumor cells and comprehensively examine the effects of microtubule-targeting agents on pancreatic carcinoma.

scholarly journals Pachytene arrest and other meiotic effects of the start mutations in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 123 (1) ◽  
pp. 29-43 ◽  
Author(s):  
E O Shuster ◽  
B Byers
Keyword(s):  
Cell Division ◽  
Nuclear Division ◽  
Spindle Pole Body ◽  
Mitotic Cell ◽  
Spindle Pole ◽  
Mitotic Cell Cycle ◽  
Chromosomal Dna ◽  
Pole Body ◽  
Vegetative Cycle

Abstract Mutations in the Start class of cell division cycle genes (CDC28, CDC36 and CDC39) define the point in the G1 phase of the vegetative cycle at which the cell becomes committed to completing another round of cell division. Genetic, cytological and biochemical data demonstrate that these mutations cause meiotic cells to become arrested at pachytene following completion of both chromosomal DNA replication and spindle pole body (SPB) duplication. In contrast these mutations have previously been found to cause arrest of the mitotic cell cycle prior to either of these landmark events, so the role of the Start genes in these events during vegetative growth must be indirect. Our observations are consistent with the hypothesis that CDC28, CDC36 and CDC39 are required for irreversible commitment to nuclear division in both the mitotic and meiotic pathways. CDC28 was additionally found to be required for the SPB separation that precedes spindle formation in preparation for the second meiotic division. Cytological and genetic analyses of this requirement revealed both that such separation may fail independently at either SPB and that ascospore formation can proceed independently of SPB separation.

Septum formation in Aspergillus nidulans

1995 ◽  
Vol 73 (S1) ◽  
pp. 396-399 ◽  
Author(s):  
Michelle Momany ◽  
Jennifer L. Morrell ◽  
Steven D. Harris ◽  
John E. Hamer
Keyword(s):  
Aspergillus Nidulans ◽  
Antibody Production ◽  
Nuclear Division ◽  
Temperature Sensitive ◽  
Cellular Processes ◽  
The Third ◽  
Septum Formation ◽  
Chromosome Transmission ◽  
Insight Into

We are investigating septation in Aspergillus nidulans. We have shown that septum formation is dependent on the third nuclear division and actin is involved in this process. We have also characterized nine temperature-sensitive septation (sep) mutants. On the basis of our analysis we have divided these mutants into three phenotypic classes. We are uncovering the order of events in the septation pathway by analysis of double mutants constructed with different pairs of sep mutants. The sepB gene has been cloned and sequenced. Homology with the Saccharomyces cerevisiae CTF4 gene and the phenotype of the sepB mutant support a role in monitoring the fidelity of chromosome transmission. We are also investigating the role of the asp genes (Aspergillus septins). Three asp genes were identified by homology with the S. cerevisiae septins. aspB has been cloned, sequenced, and fused to a biotinylated tag for antibody production. Antibody production and localization studies are now underway. Because septation requires the integration of several cellular processes, our studies should give insight into the cell cycle, cell wall biosnythesis and development of A. nidulans. Key words: septation, cytokinesis, Aspergillus nidulans.

scholarly journals The nucleation of microtubules in Aspergillus nidulans germlings

1999 ◽  
Vol 22 (3) ◽  
pp. 309-313 ◽  
Author(s):  
Cristina de Andrade-Monteiro ◽  
Nilce M. Martinez-Rossi
Keyword(s):  
Cell Division ◽  
Aspergillus Nidulans ◽  
Spindle Pole ◽  
Living Cells ◽  
Nucleation Process ◽  
Mitotic Spindles ◽  
Nuclear Movement ◽  
Microtubule Nucleation ◽  
Spindle Pole Bodies ◽  
Spindle Microtubules

Microtubules are filaments composed of dimers of alpha- and beta-tubulins, which have a variety of functions in living cells. In fungi, the spindle pole bodies usually have been considered to be microtubule-organizing centers. We used the antimicrotubule drug Benomyl in block/release experiments to depolymerize and repolymerize microtubules in Aspergillus nidulans germlings to learn more about the microtubule nucleation process in this filamentous fungus. Twenty seconds after release from Benomyl short microtubules were formed from several bright (immunofluorescent) dots distributed along the germlings, suggesting that microtubule nucleation is randomly distributed in A. nidulans germlings. Since nuclear movement is dependent on microtubules in A. nidulans we analyzed whether mutants defective in nuclear distribution along the growing hyphae (nud mutants) have some obvious microtubule defect. Cytoplasmic, astral and spindle microtubules were present and appeared to be normal in all nud mutants. However, significant changes in the percentage of short versus long mitotic spindles were observed in nud mutants. This suggests that some of the nuclei of nud mutants do not reach the late stage of cell division at normal temperatures.

scholarly journals Identification and Characterization of Genes Required for Hyphal Morphogenesis in the Filamentous Fungus Aspergillus nidulans

Genetics ◽  
1999 ◽  
Vol 151 (3) ◽  
pp. 1015-1025 ◽  
Author(s):  
Steven D Harris ◽  
Amy F Hofmann ◽  
Hugo W Tedford ◽  
Maurice P Lee
Keyword(s):  
Aspergillus Nidulans ◽  
Filamentous Fungus ◽  
Spore Germination ◽  
Temperature Sensitive ◽  
Normal Pattern ◽  
Hyphal Morphogenesis ◽  
Tube Emergence ◽  
Identification And Characterization

Abstract In the filamentous fungus Aspergillus nidulans, germination of an asexual conidiospore results in the formation of a hyphal cell. A key feature of spore germination is the switch from isotropic spore expansion to polarized apical growth. Here, temperature-sensitive mutations are used to characterize the roles of five genes (sepA, hypA, podB-podD) in the establishment and maintenance of hyphal polarity. Evidence that suggests that the hypA, podB, and sepA genes are required for multiple aspects of hyphal morphogenesis is presented. Notably, podB and sepA are needed for organization of the cytoskeleton at sites of polarized growth. In contrast, podC and podD encode proteins that appear to be specifically required for the establishment of hyphal polarity during spore germination. The role of sepA and the pod genes in controlling the spatial pattern of polarized morphogenesis in germinating spores is also described. Results obtained from these experiments indicate that the normal pattern of germ-tube emergence is dependent upon the integrity of the actin cytoskeleton.

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