scholarly journals Growth Phase Dependent Cell Shape of Haloarcula

2021 ◽  
Vol 9 (2) ◽  
pp. 231
Author(s):  
Sabine Schwarzer ◽  
Marta Rodriguez-Franco ◽  
Hanna M. Oksanen ◽  
Tessa E. F. Quax
Keyword(s):  
Growth Phase ◽  
Cell Shape ◽  
Molecular Mechanisms ◽  
Light And Electron Microscopy ◽  
Morphological Development ◽  
Motile Cells ◽  
Solid Agar ◽  
Dependent Cell ◽  
Semi Solid ◽  
Haloarcula Hispanica

Several haloarchaea are reported to be pleomorphic, while others exhibit remarkable shapes, such as squares. Recently, Haloferax volcanii was found to alter its morphology during growth. Cells are motile rods in early exponential phase, and immotile plates in stationary phase. It is unknown if this growth phase dependent cell shape alteration is a specific feature of Hfx. volcanii, or conserved amongst haloarchaea. Here, we studied the cell shape and motility of two haloarchaea species Haloarcula hispanica and Haloarcula californiae. With a combination of light and electron microscopy, we observed that both strains undergo a growth phase dependent morphological development, albeit in a slightly different fashion as Hfx. volcanii. For both Haloarcula strains, the cell size is changing throughout growth. Cell shape seems to be related with motility, as highly motile cells on semi-solid agar plates are predominantly rod-shaped. We conclude that the growth phase dependent cell morphology alteration might be a common feature amongst haloarchaea, and that cell shape is generally linked with a motile life style. The conservation of this phenomenon underscores the importance of studies of the molecular mechanisms regulating cell shape in archaea.

Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells

1995 ◽  
Vol 53 ◽  
pp. 902-903
Author(s):  
J. R. Kuhn ◽  
M. Poenie
Keyword(s):  
Mitotic Spindle ◽  
Actin Filaments ◽  
Cell Shape ◽  
Dynamic Structure ◽  
Living Cells ◽  
Cytoskeletal Proteins ◽  
Polarization Microscopy ◽  
Video Enhancement ◽  
Ultrastructural Studies ◽  
Motile Cells

Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.

scholarly journals Routes for salmonella contamination of poultry meat: epidemiological study from hatchery to slaughterhouse

2002 ◽  
Vol 129 (2) ◽  
pp. 253-265 ◽  
Author(s):  
M. HEYNDRICKX ◽  
D. VANDEKERCHOVE ◽  
L. HERMAN ◽  
I. ROLLIER ◽  
K. GRIJSPEERDT ◽  
...  
Keyword(s):  
Horizontal Transmission ◽  
Poultry Meat ◽  
Contamination Level ◽  
Solid Agar ◽  
Determining Factors ◽  
Production Stages ◽  
Animal Material ◽  
Semi Solid ◽  
Therapeutic Doses ◽  
Broiler House

Data were collected on the prevalence of salmonella at different stages during the life cycle of 18 broiler flocks on different farms as well as during slaughter in different poultry slaughterhouses. For the isolation of salmonella, the highest sensitivity (93.9%) was obtained by enrichment in the semi-solid agar Diasalm. The ‘overshoe method’ utilizing several pairs of overshoes provided the highest sensitivity for determining the salmonella status of the broilers during rearing. A clear decrease of the relative importance of the first production stages was demonstrated for the salmonella contamination of the end product, whereas horizontal transmission of salmonella to broilers during rearing and to broiler carcasses in the slaughterhouse was shown to be the main determinative factor. Ten of the 18 flocks received a salmonella positive status with the highest shedding occurring during the first 2 weeks of rearing. The shedding of the animals was significantly negatively influenced by the use of subtherapeutic or therapeutic doses of antibiotics. The intake of portable material in the broiler house was identified as the most important risk factor for horizontal transmission. Significant associations were found between the contamination level of a flock and hygiene of the broiler house, feed and water in the broiler house and both animal and non-animal material sampled in the environment. No correlation was found between contamination during the rearing period and contamination found after slaughtering. The presence of faecal material in the transport crates and predominantly the identity of the slaughterhouse seemed to be the determining factors for carcass quality. Improved hygiene management during transport of broilers and in some slaughterhouses could significantly reduce the risk of salmonella contamination of poultry meat.

scholarly journals A cryo–electron tomography workflow reveals protrusion-mediated shedding on injured plasma membrane

2021 ◽  
Vol 7 (13) ◽  
pp. eabc6345
Author(s):  
Shrawan Kumar Mageswaran ◽  
Wei Yuan Yang ◽  
Yogaditya Chakrabarty ◽  
Catherine M. Oikonomou ◽  
Grant J. Jensen
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Electron Tomography ◽  
Membrane Damage ◽  
Light And Electron Microscopy ◽  
Actin Dynamics ◽  
Endosomal Sorting ◽  
Plasma Membrane Damage ◽  
Cryo Electron Tomography ◽  
Vacuolar Protein

Cryo–electron tomography (cryo-ET) provides structural context to molecular mechanisms underlying biological processes. Although straightforward to implement for studying stable macromolecular complexes, using it to locate short-lived structures and events can be impractical. A combination of live-cell microscopy, correlative light and electron microscopy, and cryo-ET will alleviate this issue. We developed a workflow combining the three to study the ubiquitous and dynamic process of shedding in response to plasma membrane damage in HeLa cells. We found filopodia-like protrusions enriched at damage sites and acting as scaffolds for shedding, which involves F-actin dynamics, myosin-1a, and vacuolar protein sorting 4B (a component of the ‘endosomal sorting complex required for transport’ machinery). Overall, shedding is more complex than current models of vesiculation from flat membranes. Its similarities to constitutive shedding in enterocytes argue for a conserved mechanism. Our workflow can also be adapted to study other damage response pathways and dynamic cellular events.

scholarly journals Filopodyan: An open-source pipeline for the analysis of filopodia

2017 ◽  
Vol 216 (10) ◽  
pp. 3405-3422 ◽  
Author(s):  
Vasja Urbančič ◽  
Richard Butler ◽  
Benjamin Richier ◽  
Manuel Peter ◽  
Julia Mason ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Dynamic Properties ◽  
Cell Types ◽  
Molecular Heterogeneity ◽  
Interactive Editing ◽  
Motile Cells ◽  
Different Cell Types ◽  
Neuronal Growth Cones

Filopodia have important sensory and mechanical roles in motile cells. The recruitment of actin regulators, such as ENA/VASP proteins, to sites of protrusion underlies diverse molecular mechanisms of filopodia formation and extension. We developed Filopodyan (filopodia dynamics analysis) in Fiji and R to measure fluorescence in filopodia and at their tips and bases concurrently with their morphological and dynamic properties. Filopodyan supports high-throughput phenotype characterization as well as detailed interactive editing of filopodia reconstructions through an intuitive graphical user interface. Our highly customizable pipeline is widely applicable, capable of detecting filopodia in four different cell types in vitro and in vivo. We use Filopodyan to quantify the recruitment of ENA and VASP preceding filopodia formation in neuronal growth cones, and uncover a molecular heterogeneity whereby different filopodia display markedly different responses to changes in the accumulation of ENA and VASP fluorescence in their tips over time.

Mutations in the HYDRA1 gene of Arabidopsis perturb cell shape and disrupt embryonic and seedling morphogenesis

Development ◽  
1997 ◽  
Vol 124 (21) ◽  
pp. 4415-4424 ◽  
Author(s):  
J.F. Topping ◽  
V.J. May ◽  
P.R. Muskett ◽  
K. Lindsey
Keyword(s):  
Cell Expansion ◽  
Cell Shape ◽  
Bilateral Symmetry ◽  
Variable Number ◽  
Morphological Development ◽  
Size And Shape ◽  
Radial Patterning ◽  
Protein Functions ◽  
Expansion System ◽  
Embryonic Root

Mutations in the HYDRA1 (HYD1) gene of Arabidopsis thaliana can prevent normal morphological development of embryos and seedlings. Three allelic mutants (hydra 1–1, hydra1-2 and hydra1-3) have been identified, and in each the seedling is characterized by having a variable number of cotyledons, a short and wide hypocotyl and a much reduced root system. hydra1 embryos appear to develop normally to the octant stage, but fail to establish a distinct protoderm and lack bilateral symmetry, developing multiple cotyledonary primordia of irregular size and shape. Cells of the embryo proper, but not the suspensor, exhibit abnormalities in size and shape. The hydra1 embryo fails to develop an embryonic root, but embryos and seedlings express molecular markers of apical-basal polarity. Mutant seedlings produce leaves to form a small cabbage-like habit and may occasionally produce sterile flowers, though the mutation is commonly seedling-lethal. hydra1 seedlings exhibit abnormal radial patterning, but nevertheless express at least one molecular marker of vascular cell differentiation. A model is proposed in which the HYDRA1 protein functions as an essential component of the cell expansion system.

scholarly journals Cardiolipin Alters Rhodobacter sphaeroides Cell Shape by Affecting Peptidoglycan Precursor Biosynthesis

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ti-Yu Lin ◽  
William S. Gross ◽  
George K. Auer ◽  
Douglas B. Weibel
Keyword(s):  
Cell Wall ◽  
Rhodobacter Sphaeroides ◽  
Cell Morphology ◽  
Cell Shape ◽  
Molecular Mechanisms ◽  
Wild Type ◽  
Anionic Phospholipid ◽  
Content Type ◽  
Lipid Ii ◽  
Topological Features

ABSTRACT Cardiolipin (CL) is an anionic phospholipid that plays an important role in regulating protein biochemistry in bacteria and mitochondria. Deleting the CL synthase gene (Δcls) in Rhodobacter sphaeroides depletes CL and decreases cell length by 20%. Using a chemical biology approach, we found that a CL deficiency does not impair the function of the cell wall elongasome in R. sphaeroides; instead, biosynthesis of the peptidoglycan (PG) precursor lipid II is decreased. Treating R. sphaeroides cells with fosfomycin and d-cycloserine inhibits lipid II biosynthesis and creates phenotypes in cell shape, PG composition, and spatial PG assembly that are strikingly similar to those seen with R. sphaeroides Δcls cells, suggesting that CL deficiency alters the elongation of R. sphaeroides cells by reducing lipid II biosynthesis. We found that MurG—a glycosyltransferase that performs the last step of lipid II biosynthesis—interacts with anionic phospholipids in native (i.e., R. sphaeroides) and artificial membranes. Lipid II production decreases 25% in R. sphaeroides Δcls cells compared to wild-type cells, and overexpression of MurG in R. sphaeroides Δcls cells restores their rod shape, indicating that CL deficiency decreases MurG activity and alters cell shape. The R. sphaeroides Δcls mutant is more sensitive than the wild-type strain to antibiotics targeting PG synthesis, including fosfomycin, d-cycloserine, S-(3,4-dichlorobenzyl)isothiourea (A22), mecillinam, and ampicillin, suggesting that CL biosynthesis may be a potential target for combination chemotherapies that block the bacterial cell wall. IMPORTANCE The phospholipid composition of the cell membrane influences the spatial and temporal biochemistry of cells. We studied molecular mechanisms connecting membrane composition to cell morphology in the model bacterium Rhodobacter sphaeroides. The peptidoglycan (PG) layer of the cell wall is a dominant component of cell mechanical properties; consequently, it has been an important antibiotic target. We found that the anionic phospholipid cardiolipin (CL) plays a role in determination of the shape of R. sphaeroides cells by affecting PG precursor biosynthesis. Removing CL in R. sphaeroides alters cell morphology and increases its sensitivity to antibiotics targeting proteins synthesizing PG. These studies provide a connection to spatial biochemical control in mitochondria, which contain an inner membrane with topological features in common with R. sphaeroides.

scholarly journals A Polyphenol Rich Muscadine Grape Extract Reduces Triple Negative Breast Cancer Cell Migration in Association with Changes in Cell Morphology and Motility-Related Proteins

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 325-325
Author(s):  
Patricia Gallagher ◽  
Marianne Collard ◽  
Heather Brown-Harding ◽  
Elisabeth Tallant
Keyword(s):  
Breast Cancer ◽  
Cell Migration ◽  
Confocal Microscopy ◽  
Triple Negative Breast Cancer ◽  
Cell Shape ◽  
Molecular Mechanisms ◽  
Triple Negative ◽  
Dependent Manner ◽  
Grape Extract ◽  
Muscadine Grape

Abstract Objectives Triple negative breast cancer (TNBC) is a subtype of breast cancer characterized by the lack of estrogen receptors, progesterone receptors and over-expression of the human epidermal growth factor receptor 2, limiting targeted treatment.  TNBC disproportionally affects ethnic minorities and younger women and has a high propensity to metastasize, often within 5 years of diagnosis, making it one of the most aggressive breast cancer subtypes.  We showed that treatment with a proprietary muscadine grape extract (MGE) reduced the growth and metastasis of TNBC in mice.  Muscadine grapes (V. Rotundifolia) are rich in polyphenols and extracts produced from muscadine grape seed and skin are marketed as nutraceuticals for their anti-oxidant, anti-inflammatory, and anti-cancer properties.  The goal of these studies was to determine the molecular mechanisms for the reduction in metastatic growth by MGE. Methods A proprietary extract was prepared from muscadine grape seeds and skins.  Migration of MDA-MB-231 and BT-549 cells was measured by a scratch wound assay, cell shape was visualized by confocal microscopy and mRNA/proteins that participate in cell migration/motility were measured by RT-PCR and western blot hybridization. Results The extract reduced the migration of MDA-MB-231 and BT-549 TNBC cells in a dose-dependent manner.  The reduction in cell migration was associated with MGE-induced alterations in cell shape and actin filament organization, visualized by confocal microscopy.  The extract caused an apparent loss of cell polarization in MDA-MB-231 cells and a reduction in the presence of filopodia in BT-549 cells.  The MGE-induced reduction in migration and alterations in cell shape and polarization were associated with a decrease in Rho kinase ROCK1/2 mRNA and protein as well as both the mRNA and protein expression of RHAMM, a protein that is implicated in both cell motility and breast cancer progression. Conclusions These results demonstrate that a proprietary MGE reduces TNBC cell migration, in association with changes in cell shape and cytoskeleton as well as proteins that regulate migration and motility, suggesting that treatment of TNBC patients with MGE may slow or prevent metastatic progression. Funding Sources Chronic Disease Research Fund.

scholarly journals Robust kinase- and age-dependent dopaminergic and norepinephrine neurodegeneration in LRRK2 G2019S transgenic mice

2018 ◽  
Vol 115 (7) ◽  
pp. 1635-1640 ◽  
Author(s):  
Yulan Xiong ◽  
Stewart Neifert ◽  
Senthilkumar S. Karuppagounder ◽  
Qinfang Liu ◽  
Jeannette N. Stankowski ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Molecular Mechanisms ◽  
Model Development ◽  
Behavioral Deficits ◽  
Lrrk2 G2019s ◽  
Age Dependent ◽  
Dependent Cell ◽  
A Cell ◽  
Mutant Lrrk2 ◽  
Familial Parkinson’S Disease

Mutations in LRRK2 are known to be the most common genetic cause of sporadic and familial Parkinson’s disease (PD). Multiple lines of LRRK2 transgenic or knockin mice have been developed, yet none exhibit substantial dopamine (DA)-neuron degeneration. Here we develop human tyrosine hydroxylase (TH) promoter-controlled tetracycline-sensitive LRRK2 G2019S (GS) and LRRK2 G2019S kinase-dead (GS/DA) transgenic mice and show that LRRK2 GS expression leads to an age- and kinase-dependent cell-autonomous neurodegeneration of DA and norepinephrine (NE) neurons. Accompanying the loss of DA neurons are DA-dependent behavioral deficits and α-synuclein pathology that are also LRRK2 GS kinase-dependent. Transmission EM reveals that that there is an LRRK2 GS kinase-dependent significant reduction in synaptic vesicle number and a greater abundance of clathrin-coated vesicles in DA neurons. These transgenic mice indicate that LRRK2-induced DA and NE neurodegeneration is kinase-dependent and can occur in a cell-autonomous manner. Moreover, these mice provide a substantial advance in animal model development for LRRK2-associated PD and an important platform to investigate molecular mechanisms for how DA neurons degenerate as a result of expression of mutant LRRK2.

scholarly journals Disease-associated keratin mutations reduce traction forces and compromise adhesion and collective migration

2020 ◽  
Vol 133 (14) ◽  
pp. jcs243956 ◽  
Author(s):  
Sachiko Fujiwara ◽  
Shinji Deguchi ◽  
Thomas M. Magin
Keyword(s):  
Molecular Mechanisms ◽  
Adhesion Formation ◽  
Focal Adhesions ◽  
Missense Mutations ◽  
Collective Migration ◽  
Epidermolysis Bullosa Simplex ◽  
Traction Forces ◽  
Rhoa Activity ◽  
Keratin 5 ◽  
Dependent Cell

ABSTRACTKeratin intermediate filament (IF) proteins constitute the major cytoskeletal components in epithelial cells. Missense mutations in keratin 5 (K5; also known as KRT5) or keratin 14 (K14; also known as KRT14), highly expressed in the basal epidermis, cause the severe skin blistering disease epidermolysis bullosa simplex (EBS). EBS-associated mutations disrupt keratin networks and change keratinocyte mechanics; however, molecular mechanisms by which mutations shape EBS pathology remain incompletely understood. Here, we demonstrate that, in contrast to keratin-deficient keratinocytes, cells expressing K14R125C, a mutation that causes severe EBS, generate lower traction forces, accompanied by immature focal adhesions with an altered cellular distribution. Furthermore, mutant keratinocytes display reduced directionality during collective migration. Notably, RhoA activity is downregulated in human EBS keratinocytes, and Rho activation rescues stiffness-dependent cell–extracellular matrix (ECM) adhesion formation of EBS keratinocytes. Collectively, our results strongly suggest that intact keratin IF networks regulate mechanotransduction through a Rho signaling pathway upstream of cell–ECM adhesion formation and organized cell migration. Our findings provide insights into the underlying pathophysiology of EBS.This article has an associated First Person interview with the first author of the paper.

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