scholarly journals Bulk-surface coupling identifies the mechanistic connection between Min-protein patterns in vivo and in vitro

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fridtjof Brauns ◽  
Grzegorz Pawlik ◽  
Jacob Halatek ◽  
Jacob Kerssemakers ◽  
Erwin Frey ◽  
...  
Keyword(s):  
Oscillation Mode ◽  
Concentration Gradients ◽  
Protein Patterns ◽  
Spatial Control ◽  
Chamber Height ◽  
Bulk Surface ◽  
Oscillation Modes ◽  
Min Proteins

AbstractSelf-organisation of Min proteins is responsible for the spatial control of cell division in Escherichia coli, and has been studied both in vivo and in vitro. Intriguingly, the protein patterns observed in these settings differ qualitatively and quantitatively. This puzzling dichotomy has not been resolved to date. Using reconstituted proteins in laterally wide microchambers with a well-controlled height, we experimentally show that the Min protein dynamics on the membrane crucially depend on the micro chamber height due to bulk concentration gradients orthogonal to the membrane. A theoretical analysis shows that in vitro patterns at low microchamber height are driven by the same lateral oscillation mode as pole-to-pole oscillations in vivo. At larger microchamber height, additional vertical oscillation modes set in, marking the transition to a qualitatively different in vitro regime. Our work reveals the qualitatively different mechanisms of mass transport that govern Min protein-patterns for different bulk heights and thus shows that Min patterns in cells are governed by a different mechanism than those in vitro.

scholarly journals Bulk-surface coupling reconciles Min-protein pattern formation in vitro and in vivo

2020 ◽  
Author(s):  
Fridtjof Brauns ◽  
Grzegorz Pawlik ◽  
Jacob Halatek ◽  
Jacob Kerssemakers ◽  
Erwin Frey ◽  
...  
Keyword(s):  
Protein Pattern ◽  
Oscillation Mode ◽  
Coupled Systems ◽  
Protein Patterns ◽  
Spatial Control ◽  
Bulk Surface ◽  
Oscillation Modes ◽  
Min Proteins

AbstractSelf-organisation of Min proteins is responsible for the spatial control of cell division in Escherichia coli, and has been studied both in vivo and in vitro. Intriguingly, the protein patterns observed in these settings differ qualitatively and quantitatively. This puzzling dichotomy has not been resolved to date. Using reconstituted proteins in laterally wide microchambers with a well-controlled height, we show that the Min protein dynamics on the membrane crucially depend on bulk gradients normal to the membrane. A theoretical analysis shows that in vitro patterns at low bulk height are driven by the same lateral oscillation mode as pole-to-pole oscillations in vivo. At larger bulk height, additional vertical oscillation modes set in, marking the transition to a qualitatively different in vitro regime. Our work qualitatively resolves the Min system’s in vivo/in vitro conundrum and provides important insights on the mechanisms underlying protein patterns in bulk-surface coupled systems.

THE WATER AND ELECTROLYTE METABOLISM OF RAT DIAPHRAGM IN VITRO

1956 ◽  
Vol 34 (1) ◽  
pp. 1069-1083 ◽  
Author(s):  
R. H. Rixon ◽  
J. A. F. Stevenson
Keyword(s):  
Intracellular Water ◽  
Diaphragm Muscle ◽  
Optimal Conditions ◽  
Rat Diaphragm ◽  
Concentration Gradients ◽  
Hypoxic Conditions ◽  
Diaphragm In Vitro ◽  
Sodium And Potassium

The distribution of water and of sodium and potassium between the cell and synthetic environments has been studied in rat diaphragm muscle. It has been found that: (1) the amount of intracellular water is markedly increased at 0 °C. in oxygen and at 37 °C. in nitrogen compared to that of tissue at 37 °C. in oxygen, in media up to 0.75 osmolar; (2) optimal conditions of temperature and oxygen are necessary to prevent or reduce the uptake of water; (3) swelling at reduced temperatures and under hypoxic conditions is related to the oxygen uptake; (4) the loss of tissue solids during incubation does not have any significant effect on the calculation of the total tissue and intracellular water; (5) the concentration of total sodium and potassium in the tissue, in vivo and in vitro at optimal conditions is slightly in excess of that in the plasma water or incubating medium—this is believed not to represent an active hypertonicity; (6) concomitant with the uptake of water there are marked redistributions of sodium and potassium, the gain of sodium being greater than the loss of potassium. It is concluded that the swelling of tissue cells under conditions that inhibit oxidative metabolism is primarily due to the redistribution of electrolytes and that the natural distribution of water in muscle is determined by active maintenance of the concentration gradients of sodium and potassium across the cell membrane.

scholarly journals C-terminal eYFP fusion impairs Escherichia coli MinE function

Open Biology ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 200010
Author(s):  
Navaneethan Palanisamy ◽  
Mehmet Ali Öztürk ◽  
Emir Bora Akmeriç ◽  
Barbara Di Ventura
Keyword(s):  
Escherichia Coli ◽  
In Silico ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Yellow Fluorescent Protein ◽  
Time Lapse ◽  
Enhanced Yellow Fluorescent Protein ◽  
Min Proteins

The Escherichia coli Min system plays an important role in the proper placement of the septum ring at mid-cell during cell division. MinE forms a pole-to-pole spatial oscillator with the membrane-bound ATPase MinD, resulting in MinD concentration being the lowest at mid-cell. MinC, the direct inhibitor of the septum initiator protein FtsZ, forms a complex with MinD at the membrane, mirroring its polar gradients. Therefore, MinC-mediated FtsZ inhibition occurs away from mid-cell. Min oscillations are often studied in living cells by time-lapse microscopy using fluorescently labelled Min proteins. Here, we show that, despite permitting oscillations to occur in a range of protein concentrations, the enhanced yellow fluorescent protein (eYFP) C-terminally fused to MinE impairs its function. Combining in vivo , in vitro and in silico approaches, we demonstrate that eYFP compromises the ability of MinE to displace MinC from MinD, to stimulate MinD ATPase activity and to directly bind to the membrane. Moreover, we reveal that MinE-eYFP is prone to aggregation. In silico analyses predict that other fluorescent proteins are also likely to compromise several functionalities of MinE, suggesting that the results presented here are not specific to eYFP.

scholarly journals Cross-Epithelial Hydrogen Transfer from the Midgut Compartment Drives Methanogenesis in the Hindgut of Cockroaches

2001 ◽  
Vol 67 (10) ◽  
pp. 4657-4661 ◽  
Author(s):  
Thorsten Lemke ◽  
Theo van Alen ◽  
Johannes H. P. Hackstein ◽  
Andreas Brune
Keyword(s):  
Intestinal Tract ◽  
Spatial Organization ◽  
Hydrogen Transfer ◽  
Microbial Populations ◽  
Concentration Gradients ◽  
Sources And Sinks ◽  
Partial Pressures ◽  
Fermenting Bacteria

ABSTRACT In the intestinal tracts of animals, methanogenesis from CO2 and other C1 compounds strictly depends on the supply of electron donors by fermenting bacteria, but sources and sinks of reducing equivalents may be spatially separated. Microsensor measurements in the intestinal tract of the omnivorous cockroachBlaberus sp. showed that molecular hydrogen strongly accumulated in the midgut (H2 partial pressures of 3 to 26 kPa), whereas it was not detectable (<0.1 kPa) in the posterior hindgut. Moreover, living cockroaches emitted large quantities of CH4 [105 ± 49 nmol (g of cockroach)−1h−1] but only traces of H2. In vitro incubation of isolated gut compartments, however, revealed that the midguts produced considerable amounts of H2, whereas hindguts emitted only CH4 [106 ± 58 and 71 ± 50 nmol (g of cockroach)−1 h−1, respectively]. When ligated midgut and hindgut segments were incubated in the same vials, methane emission increased by 28% over that of isolated hindguts, whereas only traces of H2 accumulated in the headspace. Radial hydrogen profiles obtained under air enriched with H2 (20 kPa) identified the hindgut as an efficient sink for externally supplied H2. A cross-epithelial transfer of hydrogen from the midgut to the hindgut compartment was clearly evidenced by the steep H2 concentration gradients which developed when ligated fragments of midgut and hindgut were placed on top of each other—a configuration that simulates the situation in vivo. These findings emphasize that it is essential to analyze the compartmentalization of the gut and the spatial organization of its microbiota in order to understand the functional interactions among different microbial populations during digestion.

scholarly journals Reading of concentration gradients by axonal growth cones

2000 ◽  
Vol 355 (1399) ◽  
pp. 971-982 ◽  
Author(s):  
Jürgen Lö schinger ◽  
Franco Weth ◽  
Friedrich Bonhoeffer
Keyword(s):  
Theoretical Models ◽  
Growth Cones ◽  
Concentration Gradients ◽  
Directional Growth ◽  
Animal Development ◽  
Retinal Axons ◽  
Adaptation Model ◽  
Matching Concept

Wiring up the nervous system occurs as a self–organizing process during animal development. It has long been proposed that directional growth of axons towards their targets is achieved by gradients of guiding molecules and the conceptual framework of gradient guidance was introduced more than a decade ago. Novel experimental results now allow the formulation of models incorporating more mechanistic detail. We first summarize some crucial in vitro and in vivo results concerning the development of the chick retinotectal projection. We then review two recent theoretical models based on these findings (the models of Nakamoto and colleagues, and of Honda). Neither model considers the latest observation that putative guidance ligands, in addition to their tectal expression, are expressed in a similar pattern on the retina and that a disturbance of this expression affects topography. These findings suggest that retinal axons might grow into the tectum until they have reached a ligand concentration matching that of their site of origin. We call this the imprint–matching concept of retinotectal guidance. As a framework for pinpointing logical difficulties of the mechanistic description of the guidance process and to stimulate further experiments we finally suggest two extended versions of Honda's model implementing imprint matching, which we call ‘the variable set–point’ and ‘the gradient–sensitive adaptation’ model. Strengths and weaknesses of both mechanisms are discussed.

scholarly journals The Min-protein oscillations in Escherichia coli : an example of self-organized cellular protein waves

2018 ◽  
Vol 373 (1747) ◽  
pp. 20170111 ◽  
Author(s):  
Lukas Wettmann ◽  
Karsten Kruse
Keyword(s):  
Escherichia Coli ◽  
Cell Biology ◽  
Experimental Studies ◽  
Cellular Protein ◽  
Self Organization ◽  
Division Site ◽  
Min Proteins ◽  
Spatio Temporal

In the rod-shaped bacterium Escherichia coli , selection of the cell centre as the division site involves pole-to-pole oscillations of the proteins MinC, MinD and MinE. This spatio-temporal pattern emerges from interactions among the Min proteins and with the cytoplasmic membrane. Combining experimental studies in vivo and in vitro together with theoretical analysis has led to a fairly good understanding of Min-protein self-organization. In different geometries, the system can, in addition to standing waves, also produce travelling planar and spiral waves as well as coexisting stable stationary distributions. Today it stands as one of the best-studied examples of cellular self-organization of proteins. This article is part of the theme issue ‘Self-organization in cell biology’.

scholarly journals Prospects and Challenges of Translational Corneal Bioprinting

2020 ◽  
Vol 7 (3) ◽  
pp. 71 ◽  
Author(s):  
Matthias Fuest ◽  
Gary Hin-Fai Yam ◽  
Jodhbir S. Mehta ◽  
Daniela F. Duarte Campos
Keyword(s):  
Tissue Engineering ◽  
Ex Vivo ◽  
Corneal Transplantation ◽  
Human Cornea ◽  
Corneal Tissue ◽  
Full Thickness ◽  
Future Directions ◽  
Spatial Control

Corneal transplantation remains the ultimate treatment option for advanced stromal and endothelial disorders. Corneal tissue engineering has gained increasing interest in recent years, as it can bypass many complications of conventional corneal transplantation. The human cornea is an ideal organ for tissue engineering, as it is avascular and immune-privileged. Mimicking the complex mechanical properties, the surface curvature, and stromal cytoarchitecure of the in vivo corneal tissue remains a great challenge for tissue engineering approaches. For this reason, automated biofabrication strategies, such as bioprinting, may offer additional spatial control during the manufacturing process to generate full-thickness cell-laden 3D corneal constructs. In this review, we discuss recent advances in bioprinting and biomaterials used for in vitro and ex vivo corneal tissue engineering, corneal cell-biomaterial interactions after bioprinting, and future directions of corneal bioprinting aiming at engineering a full-thickness human cornea in the lab.

scholarly journals Proteus mirabilis isolates of different origins do not show correlation with virulence attributes and can colonize the urinary tract of mice

Microbiology ◽  
2006 ◽  
Vol 152 (7) ◽  
pp. 2149-2157 ◽  
Author(s):  
Vanessa Sosa ◽  
Geraldine Schlapp ◽  
Pablo Zunino
Keyword(s):  
Urinary Tract ◽  
Virulence Factors ◽  
Proteus Mirabilis ◽  
Protein Patterns ◽  
Wide Range ◽  
Urease Production ◽  
Tract Infections ◽  
Different Origins

Proteus mirabilis has been described as an aetiological agent in a wide range of infections, playing an important role in urinary tract infections (UTIs). In this study, a collection of P. mirabilis isolates obtained from clinical and non-clinical sources was analysed in order to determine a possible correlation between origin, virulence factors and in vivo infectivity. Isolates were characterized in vitro, assessing several virulence properties that had been previously associated with P. mirabilis uropathogenicity. Swarming motility, urease production, growth in urine, outer-membrane protein patterns, ability to grow in the presence of different iron sources, haemolysin and haemagglutinin production, and the presence and expression of diverse fimbrial genes, were analysed. In order to evaluate the infectivity of the different isolates, the experimental ascending UTI model in mice was used. Additionally, the Dienes test and the enterobacterial repetitive intergenic consensus (ERIC)-PCR assay were performed to assess the genetic diversity of the isolates. The results of the present study did not show any correlation between distribution of the diverse potential urovirulence factors and isolate source. No significant correlation was observed between infectivity and the origin of the isolates, since they all similarly colonized the urinary tract of the challenged mice. Finally, all isolates showed unique ERIC-PCR patterns, indicating that the isolates were genetically diverse. The results obtained in this study suggest that the source of P. mirabilis strains cannot be correlated with pathogenic attributes, and that the distribution of virulence factors between isolates of different origins may correspond to the opportunistic nature of the organism.

scholarly journals Mapping out Min protein patterns in fully confined fluidic chambers

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Yaron Caspi ◽  
Cees Dekker
Keyword(s):  
Diffusion Processes ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Reaction Diffusion ◽  
Bacterial Cell Division ◽  
Protein Patterns ◽  
Reaction Diffusion Systems ◽  
Characteristic Wavelength

The bacterial Min protein system provides a major model system for studying reaction-diffusion processes in biology. Here we present the first in vitro study of the Min system in fully confined three-dimensional chambers that are lithography-defined, lipid-bilayer coated and isolated through pressure valves. We identify three typical dynamical behaviors that occur dependent on the geometrical chamber parameters: pole-to-pole oscillations, spiral rotations, and traveling waves. We establish the geometrical selection rules and show that, surprisingly, Min-protein spiral rotations govern the larger part of the geometrical phase diagram. Confinement as well as an elevated temperature reduce the characteristic wavelength of the Min patterns, although even for confined chambers with a bacterial-level viscosity, the patterns retain a ~5 times larger wavelength than in vivo. Our results provide an essential experimental base for modeling of intracellular Min gradients in bacterial cell division as well as, more generally, for understanding pattern formation in reaction-diffusion systems.

108 CHARACTERIZATION OF BOVINE OVIDUCTAL EXOSOMES FROM IN VIVO AND IN VITRO ORIGIN

2015 ◽  
Vol 27 (1) ◽  
pp. 147 ◽  
Author(s):  
C. Almiñana ◽  
E. Corbin ◽  
G. Tsikis ◽  
C. Soleilhavoup ◽  
L. Galio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Profile Analysis ◽  
Protein Profile ◽  
Primary Cultures ◽  
Early Embryo ◽  
Conditioned Media ◽  
Protein Patterns ◽  
Sds Page

Successful pregnancy requires an appropriate communication between the mother and the embryo(s). Recent studies indicate that exosomes, small (30–200 nm) membrane vesicles of endocytotic origin, could act as intercellular vehicles in this unique communication system. Exosomes have been identified in vivo in all body fluids including follicular, uterine, and oviductal fluids and can be secreted by most cell types in vitro. Bovine oviductal epithelial cells (BOEC) have been thoroughly used to study embryo-maternal communication and to improve embryo development in vitro. Hence, our objective was to provide a morphologic and proteomic characterisation of exosomes secreted by BOEC in vivo in the oviductal fluid and in vitro in the conditioned media. Oviducts from cows were flushed to recover in vivo exosomes and then BOEC were scraped in order to derive primary cultures. In vitro exosomes were collected from conditioned media of BOEC primary cultures after reaching confluence (10 days). Isolation of exosomes from in vivo and in vitro origin was performed by ultracentrifugation. The presence of exosomes was confirmed in oviductal flushings and conditioned media by electron microscopy. Further characterisation of exosomes was carried out based on morphology (transmission electron microscopy), size (dynamic light scattering, DLS), and protein composition (protein profile analysis by SDS-PAGE and Western immunoblotting). Preliminary results by DLS revealed different size distribution profiles in exosome samples (in vivo: mean size of 93.41 nm; in vitro: 433.5 nm). Because exosomes are considered as “micromaps” of the originating cells, protein patterns expressed by in vivo exosomes and in vitro exosomes were compared with scraped and cultured BOEC, respectively. Protein profile analysis by SDS-PAGE showed quantitative and qualitative differences among the exosome samples, their cells of origin, and the milieu (conditioned media or flushing). Exosome-specific protein bands were detected and will be further characterised. In addition, exosomes from in vivo and in vitro origin exhibited distinct proteomic profiles. Western blot analysis demonstrated that (1) both exosomal protein samples were positive for HSP70, a known exosomal protein, and negative for Grp78, an endoplasmic reticulum marker detected in BOEC; (2) in vivo exosomes expressed oviductal glycoprotein (OVGP), heat shock protein A8 (HSPA8), and myosin 9 (MYH9), 3 oviductal proteins with known roles in fertilization and early pregnancy. However, only HSPA8 and MYH9 were detected in in vitro exosomes. Our results provide the first extensive characterisation of oviductal exosomes from in vivo and in vitro origin, an essential step in furthering our understanding of the early embryo-maternal cross talk.

Sign in / Sign up

Export Citation Format

Share Document