scholarly journals Novel chromosome organization pattern in actinomycetales–overlapping replication cycles combined with diploidy

2016 ◽  
Author(s):  
Kati Böhm ◽  
Fabian Meyer ◽  
Agata Rhomberg ◽  
Jörn Kalinowski ◽  
Catriona Donovan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Chromosome Organization ◽  
Model Species ◽  
Chromosomal Organization ◽  
Dna Segregation ◽  
Rate Dependent ◽  
Dependent Cell ◽  
Underlying Mechanisms ◽  
Cell Cycle Models

AbstractBacteria regulate chromosome replication and segregation tightly with cell division to ensure faithful segregation of DNA to daughter generations. The underlying mechanisms have been addressed in several model species. It became apparent that bacteria have evolved quite different strategies to regulate DNA segregation and chromosomal organization. We have investigated here how the actinobacteriumCorynebacterium glutamicumorganizes chromosome segregation and DNA replication. Unexpectedly, we find thatC. glutamicumcells are at least diploid under all conditions tested and that these organisms have overlapping C-periods during replication with both origins initiating replication simultaneously. Based on experimentally obtained data we propose growth rate dependent cell cycle models forC. glutamicum.

Age-dependent Cell Cycle Models

2001 ◽  
Vol 213 (1) ◽  
pp. 89-101 ◽  
Author(s):  
JOANNA TYRCHA
Keyword(s):  
Cell Cycle ◽  
Age Dependent ◽  
Dependent Cell ◽  
Cell Cycle Models

scholarly journals Bacterial chromosome segregation.

2005 ◽  
Vol 52 (1) ◽  
pp. 1-34 ◽  
Author(s):  
Aneta A Bartosik ◽  
Grazyna Jagura-Burdzy
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Copy Number ◽  
Bacterial Cells ◽  
Replication Machinery ◽  
Rapid Separation ◽  
Dna Segregation ◽  
Low Copy Number ◽  
Bacterial Chromosomes

In most bacteria two vital processes of the cell cycle: DNA replication and chromosome segregation overlap temporally. The action of replication machinery in a fixed location in the cell leads to the duplication of oriC regions, their rapid separation to the opposite halves of the cell and the duplicated chromosomes gradually moving to the same locations prior to cell division. Numerous proteins are implicated in co-replicational DNA segregation and they will be characterized in this review. The proteins SeqA, SMC/MukB, MinCDE, MreB/Mbl, RacA, FtsK/SpoIIIE playing different roles in bacterial cells are also involved in chromosome segregation. The chromosomally encoded ParAB homologs of active partitioning proteins of low-copy number plasmids are also players, not always indispensable, in the segregation of bacterial chromosomes.

scholarly journals Chromosome remodelling by SMC/Condensin in B. subtilis is regulated by Soj/ParA during growth and sporulation

2021 ◽  
Author(s):  
David M Roberts ◽  
Anna Anchimiuk ◽  
Tomas G Kloosterman ◽  
Heath Murray ◽  
Ling Juan Wu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Bacillus Subtilis ◽  
Chromosome Segregation ◽  
Chromosome Structure ◽  
Replication Initiation ◽  
Chromosome Organization ◽  
Filament Formation ◽  
Axial Filament ◽  
Dna Replication Initiation ◽  
The Web

SMC complexes, loaded at ParB-parS sites, are key mediators of chromosome organization in bacteria. ParA/Soj proteins interact with ParB/Spo0J in a pathway involving ATP-dependent dimerization and DNA binding, leading to chromosome segregation and SMC loading. In Bacillus subtilis, ParA/Soj also regulates DNA replication initiation, and along with ParB/Spo0J is involved in cell cycle changes during endospore formation. The first morphological stage in sporulation is the formation of an elongated chromosome structure called an axial filament. We now show that a major redistribution of SMC complexes drives axial filament formation, in a process regulated by ParA/Soj. Unexpectedly, this regulation is dependent on monomeric forms of ParA/Soj that cannot bind DNA or hydrolyse ATP. These results reveal a new role for ParA/Soj proteins in the regulation of SMC dynamics in bacteria, and yet further complexity in the web of interactions involving chromosome replication, segregation, and organization, controlled by ParAB and SMC.

scholarly journals Unravelling the mystery of female meiotic drive: where we are

Open Biology ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 210074
Author(s):  
Frances E. Clark ◽  
Takashi Akera
Keyword(s):  
Plant Species ◽  
Chromosome Segregation ◽  
Meiotic Drive ◽  
Genetic Element ◽  
Female Meiosis ◽  
Model Species ◽  
Selfish Genetic Element ◽  
Mendelian Expectation ◽  
Drive Systems ◽  
Underlying Mechanisms

Female meiotic drive is the phenomenon where a selfish genetic element alters chromosome segregation during female meiosis to segregate to the egg and transmit to the next generation more frequently than Mendelian expectation. While several examples of female meiotic drive have been known for many decades, a molecular understanding of the underlying mechanisms has been elusive. Recent advances in this area in several model species prompts a comparative re-examination of these drive systems. In this review, we compare female meiotic drive of several animal and plant species, highlighting pertinent similarities.

scholarly journals Rhodoccoccus erythropolis Is Different from Other Members of Actinobacteria: Monoploidy, Overlapping Replication Cycle, and Unique Segregation Pattern

2019 ◽  
Vol 201 (24) ◽  
Author(s):  
Divya Singhi ◽  
Aashima Goyal ◽  
Gunjan Gupta ◽  
Aniruddh Yadav ◽  
Preeti Srivastava
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Streptomyces Coelicolor ◽  
Rhodococcus Erythropolis ◽  
Growth Conditions ◽  
Segregation Pattern ◽  
Chromosome Organization ◽  
Content Type ◽  
Rich Media ◽  
Unique Chromosome

ABSTRACT Among actinomycetes, chromosome organization and segregation studies have been limited to Streptomyces coelicolor, Corynebacterium glutamicum, and Mycobacterium spp. There are differences with respect to ploidy and chromosome organization pattern in these bacteria. Here, we report on chromosome replication, organization, and segregation in Rhodococcus erythropolis PR4, which has a circular genome of 6.5 Mbp. The origin of replication of R. erythropolis PR4 was identified, and the DNA content in the cell under different growth conditions was determined. Our results suggest that the number of origins increases as the growth medium becomes rich, suggesting an overlapping replication cell cycle in this bacterium. Subcellular localization of the origin region revealed polar positioning in minimal and rich media. The terminus, which is the last region to be replicated and segregated, was found to be localized at the cell center in large cells. The middle markers corresponding to the 1.5-Mb and 4.7-Mb loci did not overlap, suggesting discontinuity in the segregation of the two arms of the chromosome. Chromosome segregation was not affected by inhibiting cell division. Deletion of parA or parB affected chromosome segregation. Unlike in C. glutamicum and Streptomyces spp., diploidy or polyploidy was not observed in R. erythropolis PR4. Our results suggest that R. erythropolis is different from other members of Actinobacteria; it is monoploid and has a unique chromosome segregation pattern. This is the first report on chromosome organization, replication, and segregation in R. erythropolis PR4. IMPORTANCE Rhodococci are highly versatile Gram-positive bacteria with high bioremediation potential. Some rhodococci are pathogenic and have been suggested as emerging threats. No studies on the replication, segregation, and cell cycle of these bacteria have been reported. Here, we demonstrate that the genus Rhodococcus is different from other actinomycetes, such as members of the genera Corynebacterium, Mycobacterium, and Streptomyces, with respect to ploidy and chromosome organization and segregation. Such studies will be useful not only in designing better therapeutics pathogenic strains in the future but also for studying genome maintenance in strains used for bioremediation.

scholarly journals An assay for de novo kinetochore assembly reveals a key role for the CENP-T pathway in budding yeast

2018 ◽  
Author(s):  
Jackie Lang ◽  
Adrienne Barber ◽  
Sue Biggins
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
De Novo ◽  
Budding Yeast ◽  
Centromeric Dna ◽  
Kinetochore Assembly ◽  
Ndc80 Complex ◽  
Spindle Microtubules ◽  
Underlying Mechanisms ◽  
Mitotic Phosphorylation

ABSTRACTChromosome segregation depends on the kinetochore, the machine that establishes force-bearing attachments between DNA and spindle microtubules. Kinetochores are formed every cell cycle via a highly regulated process that requires coordinated assembly of multiple subcomplexes on specialized chromatin. To elucidate the underlying mechanisms, we developed an assay to assemble kinetochores de novo using centromeric DNA and budding yeast extracts. Assembly is enhanced by mitotic phosphorylation of the Dsn1 kinetochore protein and generates kinetochores capable of binding microtubules. We used this assay to investigate why kinetochores recruit the microtubule-binding Ndc80 complex via two receptors: the Mis12 complex and CENP-T. Although the CENP-T pathway is non-essential in yeast, we demonstrate that it becomes essential for viability and Ndc80c recruitment when the Mis12 pathway is crippled by defects in Dsn1 phosphorylation. Assembling kinetochores de novo in yeast extracts provides a powerful and genetically tractable method to elucidate critical regulatory events in the future.

scholarly journals An assay for de novo kinetochore assembly reveals a key role for the CENP-T pathway in budding yeast

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Jackie Lang ◽  
Adrienne Barber ◽  
Sue Biggins
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
De Novo ◽  
Budding Yeast ◽  
Centromeric Dna ◽  
Kinetochore Assembly ◽  
Ndc80 Complex ◽  
Spindle Microtubules ◽  
Underlying Mechanisms ◽  
Mitotic Phosphorylation

Chromosome segregation depends on the kinetochore, the machine that establishes force-bearing attachments between DNA and spindle microtubules. Kinetochores are formed every cell cycle via a highly regulated process that requires coordinated assembly of multiple subcomplexes on specialized chromatin. To elucidate the underlying mechanisms, we developed an assay to assemble kinetochores de novo using centromeric DNA and budding yeast extracts. Assembly is enhanced by mitotic phosphorylation of the Dsn1 kinetochore protein and generates kinetochores capable of binding microtubules. We used this assay to investigate why kinetochores recruit the microtubule-binding Ndc80 complex via two receptors: the Mis12 complex and CENP-T. Although the CENP-T pathway is non-essential in yeast, we demonstrate that it becomes essential for viability and Ndc80c recruitment when the Mis12 pathway is crippled by defects in Dsn1 phosphorylation. Assembling kinetochores de novo in yeast extracts provides a powerful and genetically tractable method to elucidate critical regulatory events in the future.

scholarly journals Characterization of the Survival Influential Genes in Carcinogenesis

2021 ◽  
Vol 22 (9) ◽  
pp. 4384
Author(s):  
Divya Sahu ◽  
Yu-Lin Chang ◽  
Yin-Chen Lin ◽  
Chen-Ching Lin
Keyword(s):  
Cell Cycle ◽  
Cox Regression ◽  
Monte Carlo Algorithm ◽  
Functional Modules ◽  
Protective Genes ◽  
Cancer Types ◽  
Underlying Mechanisms ◽  
Patient Prognosis ◽  
Pan Cancer

The genes influencing cancer patient mortality have been studied by survival analysis for many years. However, most studies utilized them only to support their findings associated with patient prognosis: their roles in carcinogenesis have not yet been revealed. Herein, we applied an in silico approach, integrating the Cox regression model with effect size estimated by the Monte Carlo algorithm, to screen survival-influential genes in more than 6000 tumor samples across 16 cancer types. We observed that the survival-influential genes had cancer-dependent properties. Moreover, the functional modules formed by the harmful genes were consistently associated with cell cycle in 12 out of the 16 cancer types and pan-cancer, showing that dysregulation of the cell cycle could harm patient prognosis in cancer. The functional modules formed by the protective genes are more diverse in cancers; the most prevalent functions are relevant for immune response, implying that patients with different cancer types might develop different mechanisms against carcinogenesis. We also identified a harmful set of 10 genes, with potential as prognostic biomarkers in pan-cancer. Briefly, our results demonstrated that the survival-influential genes could reveal underlying mechanisms in carcinogenesis and might provide clues for developing therapeutic targets for cancers.

scholarly journals Toxicity and chemical transformation of silver nanoparticles in A549 lung cells: dose-rate-dependent genotoxic impact

2021 ◽  
Author(s):  
Laure Bobyk ◽  
Adeline Tarantini ◽  
David Beal ◽  
Giulia Veronesi ◽  
Isabelle Kieffer ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Silver Nanoparticles ◽  
Dose Rate ◽  
Cell Metabolism ◽  
A549 Cells ◽  
Dna Integrity ◽  
Lung Cells ◽  
Ag Nps ◽  
Rate Dependent ◽  
A549 Lung

Acute exposure of A549 cells to Ag-NPs induces stronger effects on DNA integrity, ROS level, cell metabolism and cell cycle than repeated exposure. Ag-NPs dissolves in both exposure conditions and Ag ions recombine with thiolated proteins.

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