scholarly journals ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation

Open Biology ◽  
2016 ◽  
Vol 6 (4) ◽  
pp. 150263 ◽  
Author(s):  
Magdalena Donczew ◽  
Paweł Mackiewicz ◽  
Agnieszka Wróbel ◽  
Klas Flärdh ◽  
Jolanta Zakrzewska-Czerwińska ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Cell Elongation ◽  
Time Lapse ◽  
Ftsz Ring ◽  
Time Lapse Microscopy ◽  
Ring Assembly ◽  
Z Ring ◽  
Nucleoprotein Complexes ◽  
A Chain ◽  
Hyphal Compartment

In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces , ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces . To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins.

scholarly journals Effects of Perturbing Nucleoid Structure on Nucleoid Occlusion-Mediated Toporegulation of FtsZ Ring Assembly

2004 ◽  
Vol 186 (12) ◽  
pp. 3951-3959 ◽  
Author(s):  
Qin Sun ◽  
William Margolin
Keyword(s):  
Chromosome Segregation ◽  
Potential Role ◽  
Membrane Insertion ◽  
Translation Inhibition ◽  
Ftsz Ring ◽  
Division Site ◽  
Ring Assembly ◽  
Z Ring ◽  
Nucleoid Structure

ABSTRACT In Escherichia coli, assembly of the FtsZ ring (Z ring) at the cell division site is negatively regulated by the nucleoid in a phenomenon called nucleoid occlusion (NO). Previous studies have indicated that chromosome packing plays a role in NO, as mukB mutants grown in rich medium often exhibit FtsZ rings on top of diffuse, unsegregated nucleoids. To address the potential role of overall nucleoid structure on NO, we investigated the effects of disrupting chromosome structure on Z-ring positioning. We found that NO was mostly normal in cells with inactivated DNA gyrase or in mukB-null mutants lacking topA, although some suppression of NO was evident in the latter case. Previous reports suggesting that transcription, translation, and membrane insertion of proteins (“transertion”) influence nucleoid structure prompted us to investigate whether disruption of these activities had effects on NO. Blocking transcription caused nucleoids to become diffuse, and FtsZ relocalized to multiple bands on top of these nucleoids, biased towards midcell. This suggested that these diffuse nucleoids were defective in NO. Blocking translation with chloramphenicol caused characteristic nucleoid compaction, but FtsZ rarely assembled on top of these centrally positioned nucleoids. This suggested that NO remained active upon translation inhibition. Blocking protein secretion by thermoinduction of a secA(Ts) strain caused a chromosome segregation defect similar to that in parC mutants, and NO was active. Although indirect effects are certainly possible with these experiments, the above data suggest that optimum NO activity may require specific organization and structure of the nucleoid.

scholarly journals The budding yeast Ipl1/Aurora protein kinase regulates mitotic spindle disassembly

2003 ◽  
Vol 160 (3) ◽  
pp. 329-339 ◽  
Author(s):  
Stéphanie Buvelot ◽  
Sean Y. Tatsutani ◽  
Danielle Vermaak ◽  
Sue Biggins
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Kinase Activity ◽  
Budding Yeast ◽  
Genomic Stability ◽  
Time Lapse ◽  
Time Lapse Microscopy ◽  
Spindle Disassembly ◽  
Spindle Midzone ◽  
Spindle Microtubules

Ipl1p is the budding yeast member of the Aurora family of protein kinases, critical regulators of genomic stability that are required for chromosome segregation, the spindle checkpoint, and cytokinesis. Using time-lapse microscopy, we found that Ipl1p also has a function in mitotic spindle disassembly that is separable from its previously identified roles. Ipl1–GFP localizes to kinetochores from G1 to metaphase, transfers to the spindle after metaphase, and accumulates at the spindle midzone late in anaphase. Ipl1p kinase activity increases at anaphase, and ipl1 mutants can stabilize fragile spindles. As the spindle disassembles, Ipl1p follows the plus ends of the depolymerizing spindle microtubules. Many Ipl1p substrates colocalize with Ipl1p to the spindle midzone, identifying additional proteins that may regulate spindle disassembly. We propose that Ipl1p regulates both the kinetochore and interpolar microtubule plus ends to regulate its various mitotic functions.

scholarly journals Microfluidic Cultivation and Laser Tweezers Raman Spectroscopy of E. coli under Antibiotic Stress

2018 ◽  
Author(s):  
Zdeněk Pilát ◽  
Silvie Bernatová ◽  
Jan Ježek ◽  
Johanna Kirchhoff ◽  
Astrid Tannert ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Cell Elongation ◽  
Time Lapse ◽  
Laser Tweezers ◽  
E Coli ◽  
Cellular Physiology ◽  
Time Lapse Microscopy ◽  
Metabolic States

Analyzing the cells in various body fluids can greatly deepen the understanding of the mechanisms governing the cellular physiology. Because of the variability of physiological and metabolic states, it is important to be able to perform such studies on individual cells. Therefore, we developed an optofluidic system in which we precisely manipulated and monitored individual cells of Escherichia coli. We used laser tweezers Raman spectroscopy (LTRS) in a microchamber chip to manipulate and analyze individual E. coli cells. We subjected the cells to antibiotic cefotaxime, and we observed the changes by the time-lapse microscopy and Raman spectroscopy. We found observable changes in the cellular morphology (cell elongation) and in Raman spectra, which were consistent with other recently published observations. We tested the capabilities of the optofluidic system and found it to be a reliable and versatile solution for this class of microbiological experiments.

scholarly journals Deletion of the min Operon Results in Increased Thermosensitivity of an ftsZ84 Mutant and Abnormal FtsZ Ring Assembly, Placement, and Disassembly

2000 ◽  
Vol 182 (21) ◽  
pp. 6203-6213 ◽  
Author(s):  
Xuan-Chuan Yu ◽  
William Margolin
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
High Frequency ◽  
Double Mutant ◽  
Nonpermissive Temperature ◽  
Ftsz Ring ◽  
Single Mutant ◽  
Ring Assembly ◽  
Z Ring ◽  
Thermosensitive Mutation

ABSTRACT To investigate the interaction between FtsZ and the Min system during cell division of Escherichia coli, we examined the effects of combining a well-known thermosensitive mutation offtsZ, ftsZ84, with ΔminCDE, a deletion of the entire min locus. Because the Min system is thought to down-regulate Z-ring assembly, the prediction was that removing minCDE might at least partially suppress the thermosensitivity of ftsZ84, which can form colonies below 42°C but not at or above 42°C. Contrary to expectations, the double mutant was significantly more thermosensitive than theftsZ84 single mutant. When shifted to the new lower nonpermissive temperature, the double mutant formed long filaments mostly devoid of Z rings, suggesting a likely cause of the increased thermosensitivity. Interestingly, even at 22°C, many Z rings were missing in the double mutant, and the rings that were present were predominantly at the cell poles. Of these, a large number were present only at one pole. These cells exhibited a higher than expected incidence of polar divisions, with a bias toward the newest pole. Moreover, some cells exhibited dramatically elongated septa that stained for FtsZ, suggesting that the double mutant is defective in Z-ring disassembly, and providing a possible mechanism for the polar bias. Thermoresistant suppressors of the double mutant arose that had modestly increased levels of FtsZ84. These cells also exhibited elongated septa and, in addition, produced a high frequency of branched cells. A thermoresistant suppressor of the ftsZ84 single mutant also synthesized more FtsZ84 and produced branched cells. The evidence from this study indicates that removing the Min system exposes and exacerbates the inherent defects of the FtsZ84 protein, resulting in clear septation phenotypes even at low growth temperatures. Increasing levels of FtsZ84 can suppress some, but not all, of these phenotypes.

scholarly journals Two-Step Assembly Dynamics of the Bacillussubtilis Divisome

2009 ◽  
Vol 191 (13) ◽  
pp. 4186-4194 ◽  
Author(s):  
Pamela Gamba ◽  
Jan-Willem Veening ◽  
Nigel J. Saunders ◽  
Leendert W. Hamoen ◽  
Richard A. Daniel
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Fluorescent Protein ◽  
Time Lapse ◽  
Localization Pattern ◽  
Ftsz Ring ◽  
Time Lapse Microscopy ◽  
Green Fluorescent ◽  
Posttranscriptional Level

ABSTRACT Cell division in bacteria is carried out by about a dozen proteins which assemble at midcell and form a complex known as the divisome. To study the dynamics and temporal hierarchy of divisome assembly in Bacillus subtilis, we have examined the in vivo localization pattern of a set of division proteins fused to green fluorescent protein in germinating spores and vegetative cells. Using time series and time-lapse microscopy, we show that the FtsZ ring assembles early and concomitantly with FtsA, ZapA, and EzrA. After a time delay of at least 20% of the cell cycle, a second set of division proteins, including GpsB, FtsL, DivIB, FtsW, Pbp2B, and DivIVA, are recruited to midcell. Together, our data provide in vivo evidence for two-step assembly of the divisome. Interestingly, overproduction of FtsZ advances the temporal assembly of EzrA but not of DivIVA, suggesting that a signal different from that of FtsZ polymerization drives the assembly of late divisome proteins. Microarray analysis shows that FtsZ depletion or overexpression does not significantly alter the transcription of division genes, supporting the hypothesis that cell division in B. subtilis is mainly regulated at the posttranscriptional level.

scholarly journals Bacillus subtilis SMC Is Required for Proper Arrangement of the Chromosome and for Efficient Segregation of Replication Termini but Not for Bipolar Movement of Newly Duplicated Origin Regions

2000 ◽  
Vol 182 (22) ◽  
pp. 6463-6471 ◽  
Author(s):  
Peter L. Graumann
Keyword(s):  
Cell Cycle ◽  
Bacillus Subtilis ◽  
Chromosome Segregation ◽  
Late Stage ◽  
Time Lapse ◽  
Chromosome Condensation ◽  
Time Lapse Microscopy ◽  
Rapid Movement ◽  
Segregation Process ◽  
Mutant Cells

ABSTRACT SMC protein is required for chromosome condensation and for the faithful segregation of daughter chromosomes in Bacillus subtilis. The visualization of specific sites on the chromosome showed that newly duplicated origin regions in growing cells of ansmc mutant were able to segregate from each other but that the location of origin regions was frequently aberrant. In contrast, the segregation of replication termini was impaired in smcmutant cells. This analysis was extended to germinating spores of ansmc mutant. The results showed that during germination, newly duplicated origins, but not termini, were able to separate from each other in the absence of SMC. Also, DAPI (4′,6′-diamidino-2-phenylindole) staining revealed that chromosomes in germinating spores were able to undergo partial or complete replication but that the daughter chromosomes were blocked at a late stage in the segregation process. These findings were confirmed by time-lapse microscopy, which showed that after duplication in growing cells the origin regions underwent rapid movement toward opposite poles of the cell in the absence of SMC. This indicates that SMC is not a required component of the mitotic motor that initially drives origins apart after their duplication. It is also concluded that SMC is needed to maintain the proper layout of the chromosome in the cell and that it functions in the cell cycle after origin separation but prior to complete segregation or replication of daughter chromosomes. It is proposed here that chromosome segregation takes place in at least two steps: an SMC-independent step in which origins move apart and a subsequent SMC-dependent step in which newly duplicated chromosomes condense and are thereby drawn apart.

Experience of using time-lapse microscopy in IVF and ICSI programs

2020 ◽  
pp. 47-50
Author(s):  
N. V. Saraeva ◽  
N. V. Spiridonova ◽  
M. T. Tugushev ◽  
O. V. Shurygina ◽  
A. I. Sinitsyna
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Selection Procedure ◽  
Time Lapse ◽  
Single Embryo Transfer ◽  
Main Group ◽  
Clinical Pregnancy ◽  
Control Group ◽  
Time Lapse Microscopy

In order to increase the pregnancy rate in the assisted reproductive technology, the selection of one embryo with the highest implantation potential it is very important. Time-lapse microscopy (TLM) is a tool for selecting quality embryos for transfer. This study aimed to assess the benefits of single-embryo transfer of autologous oocytes performed on day 5 of embryo incubation in a TLM-equipped system in IVF and ICSI programs. Single-embryo transfer following incubation in a TLM-equipped incubator was performed in 282 patients, who formed the main group; the control group consisted of 461 patients undergoing single-embryo transfer following a traditional culture and embryo selection procedure. We assessed the quality of transferred embryos, the rates of clinical pregnancy and delivery. The groups did not differ in the ratio of IVF and ICSI cycles, average age, and infertility factor. The proportion of excellent quality embryos for transfer was 77.0% in the main group and 65.1% in the control group (p = 0.001). In the subgroup with receiving eight and less oocytes we noted the tendency of receiving more quality embryos in the main group (р = 0.052). In the subgroup of nine and more oocytes the quality of the transferred embryos did not differ between two groups. The clinical pregnancy rate was 60.2% in the main group and 52.9% in the control group (p = 0.057). The delivery rate was 45.0% in the main group and 39.9% in the control group (p > 0.050).

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