scholarly journals Defective temporal and spatial control of flagellar assembly in a mutant of Chlamydomonas reinhardtii with variable flagellar number.

1985 ◽  
Vol 100 (3) ◽  
pp. 955-964 ◽  
Author(s):  
G M Adams ◽  
R L Wright ◽  
J W Jarvik
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Flagellar Apparatus ◽  
The Novel ◽  
Average Increase ◽  
Wild Type ◽  
Apical Position ◽  
Spatial Control ◽  
Flagellar Assembly ◽  
Temporal And Spatial

Wild-type Chlamydomonas reinhardtii carry two flagella per cell that are used for both motility and mating. We describe a mutant, vfl-1, in which the biflagellate state is disrupted such that the number of flagella per cell ranges from 0 to as many as 10. vfl-1 cells possess the novel ability to assemble new flagella throughout the G1 portion of the cell cycle, resulting in an average increase of about 0.05 flagella per cell per hour. Such uncoupling of the flagellar assembly cycle from the cell cycle is not observed in other mutants with abnormal flagellar number. Rather than being located in an exclusively apical position characteristic of the wild type, vfl-1 flagella can be at virtually any location on the cell surface. vfl-1 cells display abnormally wide variations in cell size, probably owing to extremely unequal cell divisions. Various ultrastructural abnormalities in the flagellar apparatus are also present, including missing or defective striated fibers and reduced numbers of rootlet microtubules. The pleiotropic defects observed in vfl-1 result from a recessive Mendelian mutation mapped to Chromosome VIII.

scholarly journals Genetic interactions at the FLA10 locus: suppressors and synthetic phenotypes that affect the cell cycle and flagellar function in Chlamydomonas reinhardtii.

Genetics ◽  
1991 ◽  
Vol 128 (3) ◽  
pp. 549-561 ◽  
Author(s):  
F G Lux ◽  
S K Dutcher
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Flagellar Apparatus ◽  
Genetic Interactions ◽  
Temperature Sensitive ◽  
Flagellar Motility ◽  
Synthetic Temperature ◽  
Flagellar Assembly ◽  
Cold Sensitive ◽  
Allele Specificity

Abstract Through the isolation of suppressors of temperature-sensitive flagellar assembly mutations at the FLA10 locus of Chlamydomonas reinhardtii, we have identified six other genes involved in flagellar assembly. Mutations at these suppressor loci, termed SUF1-SUF6, display allele specificity with respect to which fla10- mutant alleles they suppress. An additional mutation, apm1-122, which confers resistance to the plant herbicides amiprophos-methyl and oryzalin, was also found to interact with mutations at the FLA10 locus. The apm1-122 mutation in combination with three fla10- mutant alleles results in synthetic cold-sensitive cell division defects, and in combination with an additional pseudo-wild-type fla10- allele yields a synthetic temperature-sensitive flagellar motility phenotype. Based upon the genetic interactions of these loci, we propose that the FLA10 gene product interacts with multiple components of the flagellar apparatus and plays a role both in flagellar assembly and in the cell cycle.

scholarly journals Temporal and Spatial Control of HGC1 Expression Results in Hgc1 Localization to the Apical Cells of Hyphae in Candida albicans

2006 ◽  
Vol 6 (2) ◽  
pp. 253-261 ◽  
Author(s):  
Allen Wang ◽  
Shelley Lane ◽  
Zhen Tian ◽  
Amir Sharon ◽  
Idit Hazan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Candida Albicans ◽  
Protein Turnover ◽  
Growth Form ◽  
Apical Cell ◽  
Hyphal Growth ◽  
Independent Manner ◽  
Spatial Control ◽  
Apical Cells ◽  
Temporal And Spatial

ABSTRACT The human fungal pathogen Candida albicans can undergo a morphological transition from a unicellular yeast growth form to a multicellular hyphal growth form. During hyphal growth, cell division is asymmetric. Only the apical cell divides, whereas subapical cells remain in G1, and cell surface growth is highly restricted to the tip of the apical cell. Hgc1, a hypha-specific, G1 cyclin-like protein, is essential for hyphal development. Here, we report, using indirect immunofluorescence, that Hgc1 is preferentially localized to the dividing apical cells of hyphae. Hgc1 protein is rapidly degraded in a cell cycle-independent manner, and the protein turnover likely occurs in both the apical and the subapical cells of hyphae. In addition to rapid protein turnover, the HGC1 transcript is also dynamically regulated during cell cycle progression in hyphal growth. It is induced upon germ tube formation in early G1; the transcript level is reduced during the G1/S transition and peaks again around the G2/M phase in the subsequent cell cycles. Transcription from the HGC1 promoter is essential for its apical cell localization, as Hgc1 no longer exhibits preferential apical localization when expressed under the MAL2 promoter. Using fluorescence in situ hybridization, the HGC1 transcript is detected only in the apical cells of hyphae, suggesting that HGC1 is transcribed in the apical cell. Therefore, the preferential localization of Hgc1 to the apical cells of hyphae results from the dynamic temporal and spatial control of HGC1 expression.

scholarly journals The Uni2 Phosphoprotein is a Cell Cycle–regulated Component of the Basal Body Maturation Pathway in Chlamydomonas reinhardtii

2008 ◽  
Vol 19 (1) ◽  
pp. 262-273 ◽  
Author(s):  
Brian P. Piasecki ◽  
Matthew LaVoie ◽  
Lai-Wa Tam ◽  
Paul A. Lefebvre ◽  
Carolyn D. Silflow
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Basal Bodies ◽  
Mitotic Progression ◽  
Transition Zones ◽  
Phosphatase Treatment ◽  
Flagellar Assembly ◽  
A Cell ◽  
Sequential Assembly

Mutations in the UNI2 locus in Chlamydomonas reinhardtii result in a “uniflagellar” phenotype in which flagellar assembly occurs preferentially from the older basal body and ultrastructural defects reside in the transition zones. The UNI2 gene encodes a protein of 134 kDa that shares 20.5% homology with a human protein. Immunofluorescence microscopy localized the protein on both basal bodies and probasal bodies. The protein is present as at least two molecular-weight variants that can be converted to a single form with phosphatase treatment. Synthesis of Uni2 protein is induced during cell division cycles; accumulation of the phosphorylated form coincides with assembly of transition zones and flagella at the end of the division cycle. Using the Uni2 protein as a cell cycle marker of basal bodies, we observed migration of basal bodies before flagellar resorption in some cells, indicating that flagellar resorption is not required for mitotic progression. We observed the sequential assembly of new probasal bodies beginning at prophase. The uni2 mutants may be defective in the pathways leading to flagellar assembly and to basal body maturation.

Extragenic Bypass Suppressors of Mutations in the Essential Gene BLD2 Promote Assembly of Basal Bodies With Abnormal Microtubules in Chlamydomonas reinhardtii

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 163-181
Author(s):  
Andrea M Preble ◽  
Thomas H Giddings ◽  
Susan K Dutcher
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Insertional Mutagenesis ◽  
Essential Gene ◽  
Basal Bodies ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Lethal Phenotype ◽  
Flagellar Assembly ◽  
And Function

Abstract bld2-1 mutant Chlamydomonas reinhardtii strains assemble basal bodies with singlet microtubules; bld2-1 cells display flagellar assembly defects as well as positioning defects of the mitotic spindle and cleavage furrow. To further understand the role of the BLD2 gene, we have isolated three new bld2 alleles and three partially dominant extragenic suppressors, rgn1-1, rgn1-2, and rgn1-3. bld2 rgn1-1 strains have phenotypes intermediate between those of bld2 and wild-type strains with respect to flagellar number, microtubule rootlet organization, cleavage furrow positioning, and basal body structural phenotypes. Instead of the triplet microtubules of wild-type cells, bld2 rgn1-1 basal bodies have mixtures of no, singlet, doublet, and triplet microtubules. The bld2-4 allele was made by insertional mutagenesis and identified in a noncomplementation screen in a diploid strain. The bld2-4 allele has a lethal phenotype based on mitotic segregation in diploid strains and in haploid strains generated by meiotic recombination. The lethal phenotype in haploid strains is suppressed by rgn1-1; these suppressed strains have similar phenotypes to other bld2 rgn1-1 double mutants. It is likely that BLD2 is an essential gene that is needed for basal body assembly and function.

scholarly journals Temperature-sensitive mutations affecting flagellar assembly and function in Chlamydomonas reinhardtii.

1977 ◽  
Vol 72 (1) ◽  
pp. 67-85 ◽  
Author(s):  
B Huang ◽  
M R Rifkin ◽  
D J Luck
Keyword(s):  
Cell Growth ◽  
Chlamydomonas Reinhardtii ◽  
Temperature Sensitive ◽  
Genetic Dissection ◽  
Recombination Analysis ◽  
Wild Type ◽  
Tetrad Analysis ◽  
Flagellar Assembly ◽  
And Function ◽  
Combined Defects

A series of conditional mutants of the algal, biflagellate Chlamydomonas reinhardtii with temperature-sensitive defects in flagellar assembly and function were isolated. The genetics and phenotypes of 21 mutants displaying a rapid alteration in flagellar function upon shift from the permissive (20 degrees C) to the restrictive (32 degrees C) temperatures are described. These mutants designated as "drop-down" or dd-mutants have been placed in four categories on the basis of their defective phenotypes: (a) dd-assembly mutants - the preformed flagella are resorbed at 32 degrees C and reassembly of flagella is inhibited; (b) dd-fragile flagella mutants - the flagella are lost by detachment at 32 degrees C, but can be reassembled; (c) dd-motility mutants - the flagella are retained at 32 degrees C, but are functionally defective; (d) dd-lethal mutants - display combined defects in flagellar function and cell growth. Tetrad analysis of the mutants back-crossed to wild-type, recombination analysis of intermutant crosses, and complementation tests in the construction of heterozygous diploid strains indicate that at least 14 nuclear genetic loci are represented among 21 mutants. The availability of temperature-sensitive mutations affecting the assembly and function of the flagellum suggests that the morphogenesis of this complex eukaryotic organelle is amenable to genetic dissection.

Yeast dom34 Mutants Are Defective in Multiple Developmental Pathways and Exhibit Decreased Levels of Polyribosomes

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 45-56
Author(s):  
Luther Davis ◽  
JoAnne Engebrecht
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Heterologous Expression ◽  
Protein Translation ◽  
Developmental Pathways ◽  
G1 Phase ◽  
Growth Defect ◽  
Wild Type ◽  
Drosophila Homolog ◽  
Mutant Cells

Abstract The DOM34 gene of Saccharomyces cerevisiae is similar togenes found in diverse eukaryotes and archaebacteria. Analysis of dom34 strains shows that progression through the G1 phase of the cell cycle is delayed, mutant cells enter meiosis aberrantly, and their ability to form pseudohyphae is significantly diminished. RPS30A, which encodes ribosomal protein S30, was identified in a screen for high-copy suppressors of the dom34Δ growth defect. dom34Δ mutants display an altered polyribosome profile that is rescued by expression of RPS30A. Taken together, these data indicate that Dom34p functions in protein translation to promote G1 progression and differentiation. A Drosophila homolog of Dom34p, pelota, is required for the proper coordination of meiosis and spermatogenesis. Heterologous expression of pelota in dom34Δ mutants restores wild-type growth and differentiation, suggesting conservation of function between the eukaryotic members of the gene family.

scholarly journals The Anti-Tumor Activity of the NEDD8 Inhibitor Pevonedistat in Neuroblastoma

2021 ◽  
Vol 22 (12) ◽  
pp. 6565
Author(s):  
Jennifer H. Foster ◽  
Eveline Barbieri ◽  
Linna Zhang ◽  
Kathleen A. Scorsone ◽  
Myrthala Moreno-Smith ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Lines ◽  
Neuroblastoma Cell ◽  
Wild Type ◽  
Tumor Weight ◽  
Cycle Arrest ◽  
P53 Status ◽  
Neuroblastoma Cell Lines ◽  
Anti Tumor Activity

Pevonedistat is a neddylation inhibitor that blocks proteasomal degradation of cullin–RING ligase (CRL) proteins involved in the degradation of short-lived regulatory proteins, including those involved with cell-cycle regulation. We determined the sensitivity and mechanism of action of pevonedistat cytotoxicity in neuroblastoma. Pevonedistat cytotoxicity was assessed using cell viability assays and apoptosis. We examined mechanisms of action using flow cytometry, bromodeoxyuridine (BrDU) and immunoblots. Orthotopic mouse xenografts of human neuroblastoma were generated to assess in vivo anti-tumor activity. Neuroblastoma cell lines were very sensitive to pevonedistat (IC50 136–400 nM). The mechanism of pevonedistat cytotoxicity depended on p53 status. Neuroblastoma cells with mutant (p53MUT) or reduced levels of wild-type p53 (p53si-p53) underwent G2-M cell-cycle arrest with rereplication, whereas p53 wild-type (p53WT) cell lines underwent G0-G1 cell-cycle arrest and apoptosis. In orthotopic neuroblastoma models, pevonedistat decreased tumor weight independent of p53 status. Control mice had an average tumor weight of 1.6 mg + 0.8 mg versus 0.5 mg + 0.4 mg (p < 0.05) in mice treated with pevonedistat. The mechanism of action of pevonedistat in neuroblastoma cell lines in vitro appears p53 dependent. However, in vivo studies using mouse neuroblastoma orthotopic models showed a significant decrease in tumor weight following pevonedistat treatment independent of the p53 status. Novel chemotherapy agents, such as the NEDD8-activating enzyme (NAE) inhibitor pevonedistat, deserve further study in the treatment of neuroblastoma.

scholarly journals To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 861
Author(s):  
Veronika Kselíková ◽  
Vilém Zachleder ◽  
Kateřina Bišová
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Cell Cycle Progression ◽  
Model Organism ◽  
Cycle Progression ◽  
Synchronous Cultures ◽  
Multiple Fission ◽  
First Choice ◽  
High Doses

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

Sign in / Sign up

Export Citation Format

Share Document