Septa ultrastructure and hyphal branching in the pleomorphic imperfect fungus Trichosporonoides oedocephalis

1975 ◽  
Vol 53 (11) ◽  
pp. 1139-1148 ◽  
Author(s):  
R. H. Haskins
Keyword(s):  
Cell Division ◽  
Osmic Acid ◽  
Basidiomycetous Yeasts ◽  
Hyphal Branching ◽  
Septum Formation ◽  
Imperfect Fungus ◽  
Trichosporonoides Oedocephalis

Incomplete septa, complete simple septa, septa with simple pores, but mostly dolipore septa without pore caps or parenthosomes are present in this organism. Walls are distinctly laminar in aspect, especially with glutaraldehyde – osmic acid fixation. Cell division is by septum formation between previously formed septa. Conidia result from either blastospore or endospore (arthrospore) formation. Branching occurs irrespective of the type of adjacent septa, with each cell capable of bipolar germination. The organism shows features of both ascomycetous and basidiomycetous yeasts.

scholarly journals MinC, MinD, and MinE Drive Counter-oscillation of Early-Cell-Division Proteins Prior to Escherichia coli Septum Formation

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Paola Bisicchia ◽  
Senthil Arumugam ◽  
Petra Schwille ◽  
David Sherratt
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Lipid Bilayers ◽  
Epifluorescence Microscopy ◽  
Bacterial Cell Division ◽  
Content Type ◽  
Septum Formation ◽  
Early Stages ◽  
Z Ring ◽  
High Concentrations

ABSTRACTBacterial cell division initiates with the formation of a ring-like structure at the cell center composed of the tubulin homolog FtsZ (the Z-ring), which acts as a scaffold for the assembly of the cell division complex, the divisome. Previous studies have suggested that the divisome is initially composed of FtsZ polymers stabilized by membrane anchors FtsA and ZipA, which then recruit the remaining division proteins. The MinCDE proteins prevent the formation of the Z-ring at poles by oscillating from pole to pole, thereby ensuring that the concentration of the Z-ring inhibitor, MinC, is lowest at the cell center. We show that prior to septum formation, the early-division proteins ZipA, ZapA, and ZapB, along with FtsZ, assemble into complexes that counter-oscillate with respect to MinC, and with the same period. We propose that FtsZ molecules distal from high concentrations of MinC form relatively slowly diffusing filaments that are bound by ZapAB and targeted to the inner membrane by ZipA or FtsA. These complexes may facilitate the early stages of divisome assembly at midcell. As MinC oscillates toward these complexes, FtsZ oligomerization and bundling are inhibited, leading to shorter or monomeric FtsZ complexes, which become less visible by epifluorescence microscopy because of their rapid diffusion. Reconstitution of FtsZ-Min waves on lipid bilayers shows that FtsZ bundles partition away from high concentrations of MinC and that ZapA appears to protect FtsZ from MinC by inhibiting FtsZ turnover.IMPORTANCEA big issue in biology for the past 100 years has been that of how a cell finds its middle. InEscherichia coli, over 20 proteins assemble at the cell center at the time of division. We show that the MinCDE proteins, which prevent the formation of septa at the cell pole by inhibiting FtsZ, drive the counter-oscillation of early-cell-division proteins ZapA, ZapB, and ZipA, along with FtsZ. We propose that FtsZ forms filaments at the pole where the MinC concentration is the lowest and acts as a scaffold for binding of ZapA, ZapB, and ZipA: such complexes are disassembled by MinC and reform within the MinC oscillation period before accumulating at the cell center at the time of division. The ability of FtsZ to be targeted to the cell center in the form of oligomers bound by ZipA and ZapAB may facilitate the early stages of divisome assembly.

scholarly journals DivIVA is essential in Deinococcus radiodurans and its C terminal domain regulates new septum orientation during cell division

2020 ◽  
Author(s):  
Reema Chaudhary ◽  
Swathi Kota ◽  
Hari S Misra
Keyword(s):  
Cell Division ◽  
Deinococcus Radiodurans ◽  
Wild Type ◽  
Orthogonal Axis ◽  
Septum Formation ◽  
Terminal Domain ◽  
Cell Position ◽  
Type Pattern ◽  
In Trans ◽  
Ftsz Assembly

AbstractFtsZ assembly at mid cell position in rod shaped bacteria is regulated by gradient of MinCDE complex across the poles. In round shaped bacteria, which lack predefined poles and the next plane of cell division is perpendicular to previous plane, the determination of site for FtsZ assembly is intriguing. Deinococcus radiodurans a coccus shaped bacterium, is characterized for its extraordinary resistance to DNA damage. Here we report that DivIVA a putative component of Min system in this bacterium (drDivIVA) interacts with cognate cell division and genome segregation proteins. The deletion of full length drDivIVA was found to be indispensable while its C-terminal deletion (ΔdivIVAC) was dispensable but produced distinguishable phenotypes like slow growth, altered plane for new septum formation and angular septum. Both wild type and mutant showed FtsZ foci formation and their gamma radiation responses were nearly identical. But unlike in wild type, the FtsZ localization in mutant cells was found to be away from orthogonal axis with respect to plane of previous septum. Notably, DivIVA-RFP localizes to membrane during cell division and then perpendicular to previous plane of cell division. In trans expression of drDivIVA in ΔdivIVAC background could restore the wild type pattern of septum formation perpendicular to previous septum. These results suggested that DivIVA is an essential protein in D. radiodurans and the C-terminal domain that contributes to its interaction with MinC determines the plane of new septum formation, possibly by controlling MinC oscillation through orthogonal axis in the cells.

A pathway of plasma membrane biogenesis bypassing the Golgi apparatus during cell division in the green alga Cylindrocapsa geminella

1984 ◽  
Vol 72 (1) ◽  
pp. 89-100
Author(s):  
H.J. Sluiman
Keyword(s):  
Plasma Membrane ◽  
Cell Division ◽  
Golgi Apparatus ◽  
Cell Plate ◽  
Membrane Biogenesis ◽  
Membrane Flow ◽  
Septum Formation ◽  
Primary Septum ◽  
Rough Er ◽  
And Function

Cell division in Cylindrocapsa geminella, in particular the mode of septum membrane biogenesis, has been studied with the transmission electron microscope. Septum formation takes place in a narrow layer of cytoplasm separating post-mitotic nuclei. First, each daughter nucleus develops a wide cytoplasmic pocket (invagination) containing numerous strands of rough endoplasmic reticulum (ER). Next, a proliferation of rough ER is observed in the equatorial zone of cytoplasm, which invariably contains a small number of widely scattered microtubules. The equatorially aligned cisternae of rough ER produce smooth-membraned vesicles, interpreted as smooth ER, which subsequently coalesce to form the membranous transverse septum. Thus, primary septum formation does not follow any of the two previously known basic cytokinetic patterns in green plants (i.e. plasma membrane furrowing and cell-plate formation), but instead represents a novel type of membrane flow, which effectively bypasses the Golgi apparatus. This pathway of membrane flow has remained largely ignored in current concepts of endomembrane structure and function in eukaryotes. However, it appears to be more widespread than has previously been recognized, especially in autospore-producing green algae and in red algae during the formation of tetraspores. It may represent an evolutionary intermediate type of cell division between the supposedly primitive method of plasma membrane furrowing and the more advanced cell-plate system.

scholarly journals Isolation and Characterization of New Fission Yeast Cytokinesis Mutants

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1265-1275 ◽  
Author(s):  
Mohan K Balasubramanian ◽  
Dannel McCollum ◽  
Louise Chang ◽  
Kelvin C Y Wong ◽  
Naweed I Naqvi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Genetic Screen ◽  
Contractile Ring ◽  
Medial Region ◽  
Septum Formation ◽  
Isolation And Characterization ◽  
Gtp Binding ◽  
Division Process

Abstract Schizosaccharomyces pombe is an excellent organism in which to study cytokinesis as it divides by medial fission using an F-actin contractile ring. To enhance our understanding of the cell division process, a large genetic screen was carried out in which 17 genetic loci essential for cytokinesis were identified, 5 of which are novel. Mutants identifying three genes, rng3+, rng4+, and rng5+, were defective in organizing an actin contractile ring. Four mutants defective in septum deposition, septum initiation defective (sid)1, sid2, sid3, and sid4, were also identified and characterized. Genetic analyses revealed that the sid mutants display strong negative interactions with the previously described septation mutants cdc7-24, cdc11-123, and cdc14-118. The rng5+, sid2+, and sid3+ genes were cloned and shown to encode Myo2p (a myosin heavy chain), a protein kinase related to budding yeast Dbf2p, and Spg1p, a GTP binding protein that is a member of the ras superfamily of GTPases, respectively. The ability of Spg1p to promote septum formation from any point in the cell cycle depends on the activity of Sid4p. In addition, we have characterized a phenotype that has not been described previously in cytokinesis mutants, namely the failure to reorganize actin patches to the medial region of the cell in preparation for septum formation.

Ultrastructure and cell division of an oral bacterium resembling Alysiella filiformis

1973 ◽  
Vol 19 (3) ◽  
pp. 325-327 ◽  
Author(s):  
Gary E. Kaiser ◽  
Marvin J. Starzyk
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Epithelial Cells ◽  
Oral Cavity ◽  
Structural Study ◽  
Cell Separation ◽  
Septum Formation ◽  
Innermost Layer ◽  
Oral Bacterium

Alysiella filiformis is commonly found on the epithelial cells of the oral cavity in rabbits. An ultra-structural study of these cells has shown A. filiformis attached by numerous slime appendages (setae) to the host epithelial cells. The organism possesses a multilayered cell wall 18–22 nm thick. Cell division occurs by constriction of the cytoplasm with concurrent septum formation initiating from the dense innermost layer of the cell wall. This is followed by thickening and delamination of the septum with subsequent invagination of the outer layers of the cell wall causing a partial cell separation. However, the cells of the typical trichomes are still held together by septal bridges. Mesosome-like structures were occasionally found and were often in the area of septum formation. All attempts to culture this organism in vitro were unsuccessful.

scholarly journals Long-Chain Polyphosphate Causes Cell Lysis and Inhibits Bacillus cereus Septum Formation, Which Is Dependent on Divalent Cations

1999 ◽  
Vol 65 (9) ◽  
pp. 3942-3949 ◽  
Author(s):  
Simon K. Maier ◽  
Siegfried Scherer ◽  
Martin J. Loessner
Keyword(s):  
Cell Division ◽  
Metal Ions ◽  
Bacillus Cereus ◽  
Metal Ion ◽  
Divalent Cations ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Septum Formation ◽  
Cell Counts ◽  
Long Chain

ABSTRACT We investigated the cellular mechanisms that led to growth inhibition, morphological changes, and lysis of Bacillus cereus WSBC 10030 when it was challenged with a long-chain polyphosphate (polyP). At a concentration of 0.1% or higher, polyP had a bacteriocidal effect on log-phase cells, in which it induced rapid lysis and reductions in viable cell counts of up to 3 log units. The cellular debris consisted of empty cell wall cylinders and polar caps, suggesting that polyP-induced lysis was spatially specific. This activity was strictly dependent on active growth and cell division, since polyP failed to induce lysis in cells treated with chloramphenicol and in stationary-phase cells, which were, however, bacteriostatically inhibited by polyP. Similar observations were made with B. cereus spores; 0.1% polyP inhibited spore germination and outgrowth, and a higher concentration (1.0%) was even sporocidal. Supplemental divalent metal ions (Mg2+ and Ca2+) could almost completely block and reverse the antimicrobial activity of polyP; i.e., they could immediately stop lysis and reinitiate rapid cell division and multiplication. Interestingly, a sublethal polyP concentration (0.05%) led to the formation of elongated cells (average length, 70 μm) after 4 h of incubation. While DNA replication and chromosome segregation were undisturbed, electron microscopy revealed a complete lack of septum formation within the filaments. Exposure to divalent cations resulted in instantaneous formation and growth of ring-shaped edges of invaginating septal walls. After approximately 30 min, septation was complete, and cell division resumed. We frequently observed a minicell-like phenotype and other septation defects, which were probably due to hyperdivision activity after cation supplementation. We propose that polyP may have an effect on the ubiquitous bacterial cell division protein FtsZ, whose GTPase activity is known to be strictly dependent on divalent metal ions. It is tempting to speculate that polyP, because of its metal ion-chelating nature, indirectly blocks the dynamic formation (polymerization) of the Z ring, which would explain the aseptate phenotype.

scholarly journals Cell Division Inhibition in Salmonella typhimuriumHistidine-Constitutive Strains: an ftsI-Like Defect in the Presence of Wild-Type Penicillin-Binding Protein 3 Levels

1998 ◽  
Vol 180 (19) ◽  
pp. 5231-5234 ◽  
Author(s):  
David A. Cano ◽  
Chakib Mouslim ◽  
Juan A. Ayala ◽  
Francisco García-del Portillo ◽  
Josep Casadesús
Keyword(s):  
Cell Division ◽  
Carbon Source ◽  
Salmonella Typhimurium ◽  
Binding Protein ◽  
Penicillin Binding Protein ◽  
Wild Type ◽  
Septum Formation ◽  
Phenotypic Suppression ◽  
High Concentrations ◽  
Cell Division Inhibition

ABSTRACT Histidine-constitutive (Hisc) strains ofSalmonella typhimurium undergo cell division inhibition in the presence of high concentrations of a metabolizable carbon source. Filaments formed by Hisc strains show constrictions and contain evenly spaced nucleoids, suggesting a defect in septum formation. Inhibitors of penicillin-binding protein 3 (PBP3) induce a filamentation pattern identical to that of Hisc strains. However, the Hisc septation defect is caused neither by reduced PBP3 synthesis nor by reduced PBP3 activity. Gross modifications of peptidoglycan composition are also ruled out.d-Cycloserine, an inhibitor of the soluble pathway producing peptidoglycan precursors, causes phenotypic suppression of filamentation, suggesting that the septation defect of Hiscstrains may be caused by scarcity of PBP3 substrate.

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