Origins of eukaryotic excitability

All living cells interact dynamically with a constantly changing world. Eukaryotes, in particular, evolved radically new ways to sense and react to their environment. These advances enabled new and more complex forms of cellular behaviour in eukaryotes, including directional movement, active feeding, mating, and responses to predation. But what are the key events and innovations during eukaryogenesis that made all of this possible? Here we describe the ancestral repertoire of eukaryotic excitability and discuss five major cellular innovations that enabled its evolutionary origin. The innovations include a vastly expanded repertoire of ion channels, the emergence of cilia and pseudopodia, endomembranes as intracellular capacitors, a flexible plasma membrane and the relocation of chemiosmotic ATP synthesis to mitochondria, which liberated the plasma membrane for more complex electrical signalling involved in sensing and reacting. We conjecture that together with an increase in cell size, these new forms of excitability greatly amplified the degrees of freedom associated with cellular responses, allowing eukaryotes to vastly outperform prokaryotes in terms of both speed and accuracy. This comprehensive new perspective on the evolution of excitability enriches our view of eukaryogenesis and emphasizes behaviour and sensing as major contributors to the success of eukaryotes. This article is part of the theme issue ‘Basal cognition: conceptual tools and the view from the single cell’.

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Organization of the Pellicle and the Muciferous Glands in Euglena Gracilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067510 ◽

1970 ◽

Vol 28 ◽

pp. 104-105

Author(s):

Hilton H. Mollenhauer ◽

W. Evans

Keyword(s):

Plasma Membrane ◽

Euglena Gracilis ◽

Complex Forms ◽

Secondary Periodicity

The pellicular structure of Euglena gracilis consists of a series of relatively rigid strips (Fig. 1) composed of ridges and grooves which are helically oriented along the cell and which fuse together into a common junction at either end of the cell. The strips are predominantly protein and consist in part of a series of fibers about 50 Å in diameter spaced about 85 Å apart and with a secondary periodicity of about 450 Å. Microtubules are also present below each strip (Fig. 1) and are often considered as part of the pellicular complex. In addition, there may be another fibrous component near the base of the pellicle which has not yet been very well defined.The pellicular complex lies underneath the plasma membrane and entirely within the cell (Fig. 1). Each strip of the complex forms an overlapping junction with the adjacent strip along one side of each groove (Fig. 1), in such a way that a certain amount of sideways movement is possible between one strip and the next.

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Plasma membrane glycosphingolipid signaling: a turning point

Glycoconjugate Journal ◽

10.1007/s10719-021-10008-w ◽

2021 ◽

Author(s):

Elena Chiricozzi

Keyword(s):

Plasma Membrane ◽

Chemical Synthesis ◽

Bioinformatic Analysis ◽

Membrane Receptors ◽

Outer Side ◽

Neuronal Homeostasis ◽

Extracellular Stimuli ◽

Conceptual Shift ◽

Plasma Membrane Receptors ◽

Key Events

AbstractPlasma membrane interaction is highly recognized as an essential step to start the intracellular events in response to extracellular stimuli. The ways in which these interactions take place are less clear and detailed. Over the last decade my research has focused on developing the understanding of the glycosphingolipids-protein interaction that occurs at cell surface. By using chemical synthesis and biochemical approaches we have characterized some fundamental interactions that are key events both in the immune response and in the maintenance of neuronal homeostasis. In particular, for the first time it has been demonstrated that a glycolipid, present on the outer side of the membrane, the long-chain lactosylceramide, is able to directly modulate a cytosolic protein. But the real conceptual change was the demonstration that the GM1 oligosaccharide chain is able, alone, to replicate numerous functions of GM1 ganglioside and to directly interact with plasma membrane receptors by activating specific cellular signaling. In this conceptual shift, the development and application of multidisciplinary techniques in the field of biochemistry, from chemical synthesis to bioinformatic analysis, as well as discussions with several national and international colleagues have played a key role.

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Exogenous energy supply to the plasma membrane of dark anaerobic cyanobacterium Anacystis nidulans: Thermodynamic and kinetic characterization of the ATP synthesis effected by an artificial proton motive force

Archives of Biochemistry and Biophysics ◽

10.1016/0003-9861(86)90530-8 ◽

1986 ◽

Vol 247 (1) ◽

pp. 40-48 ◽

Cited By ~ 13

Author(s):

G.A. Peschek ◽

B. Hinterstoisser ◽

M. Riedler ◽

R. Muchl ◽

W.H. Nitschmann

Keyword(s):

Plasma Membrane ◽

Energy Supply ◽

Atp Synthesis ◽

Anacystis Nidulans ◽

Proton Motive Force ◽

Motive Force ◽

Kinetic Characterization

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The secretory pathway of bovine platelets

Blood ◽

10.1182/blood.v69.3.878.878 ◽

1987 ◽

Vol 69 (3) ◽

pp. 878-885 ◽

Cited By ~ 5

Author(s):

JG White

Keyword(s):

Plasma Membrane ◽

Secretory Pathway ◽

Human Platelet ◽

Surface Membrane ◽

Surrounding Medium ◽

Human Platelets ◽

Resting Cells ◽

Granule Secretion ◽

New Perspective ◽

Platelet Secretion

Abstract Human platelets contain tortuous channels in their cytoplasm, the surface-connected or open canalicular system (OCS), that communicate directly with the surrounding medium through openings on the surface membrane. Some workers have suggested that the OCS serves as the egress route for products secreted during the release reaction. Others have proposed alternate secretory pathways. Since bovine platelets lack the OCS found in human cells, the present study has examined the secretory mechanism of these cells to see whether it can shed light on the mystery of human platelet secretion. Bovine platelet granules, in contrast to human granules, are located more peripherally in resting cells (often in contact with the plasma membrane), most do not move centrally following thrombin stimulation as do human platelet granules, and many fuse directly with the external plasma membrane without any intermediate channel. The lack of peripheral location of human granules, their central rather than peripheral movement during secretion, and the presence of extensive channels are all consistent with the larger importance of the secretory channel to human platelets. Thus, though studies of bovine secretion do show that platelets can secrete their granules by direct fusion of granule and surface membranes, other differences from human platelets emphasize that this pathway, although important to bovine platelet secretion, is less important in human platelets. Studies of bovine platelets also show that the OCS is more dynamic than might have been considered from human studies and can form rapidly in response to stimulation. Such newly formed channels are used as a conduit for secretion of granule contents. The finding emphasizes the importance of channels for granule secretion in platelets generally and puts a new perspective on the ability of these cells to form channels rapidly in response to stimulation.

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TECHNICAL PROPERTIES AND RESEARCH CAPABILITIES OF THE TRUCK SIMULATOR OWNED BY THE MILITARY INSTITUTE OF AVIATION MEDICINE – A NEW PERSPECTIVE IN RESEARCH ON TRUCK DRIVERS

The Polish Journal of Aviation Medicine Bioengineering and Psychology ◽

10.13174/pjambp.19.05.2021.04 ◽

2021 ◽

Vol 25 (3) ◽

pp. 26-31

Author(s):

PAULINA BARAN ◽

◽

MARIUSZ KREJ ◽

MARCIN PIOTROWSKI ◽

ŁUKASZ DZIUDA ◽

...

Keyword(s):

Degrees Of Freedom ◽

Driving Simulator ◽

Truck Drivers ◽

Aviation Medicine ◽

Motion System ◽

Technical Properties ◽

Conducting Research ◽

New Perspective ◽

Military Institute ◽

The Military

Abstract: This paper is aimed at presenting basic technical properties and possibilities of using the truck simulator owned by the Military Institute of Aviation Medicine (MIAM). The truck driving simulator is a stationary device, equipped with a six degrees of freedom (6 DoF|) motion system and reproducing the functionality of a truck on the basis of the Mercedes Benz Actros cabin. It is intended for conducting research as well as training truck drivers in simulated traffic conditions.

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New perspective? Comparing Frame Occurrence in Online and Traditional News Media Reporting on Europe’s “Migration Crisis”

10.31235/osf.io/h3tpy ◽

2019 ◽

Author(s):

Christian S. Czymara ◽

Marijn van Klingeren

Keyword(s):

Machine Learning ◽

News Media ◽

Print Media ◽

Online News ◽

Online Media ◽

Media Reporting ◽

Machine Learning Methods ◽

Migration Crisis ◽

New Perspective ◽

Key Events

News media have shape-shifted over the last decades, with rising online news suppliers and an increase in online news consumption. We examine how reporting on immigration differs between popular German online and print media over three crucial years of the so-called immigration crisis, from 2015 to 2017. We extend knowledge on framing of the crisis by examining a period covering start, peak and the time after the intake of refugees. Moreover, we establish whether online and print reporting differs in terms of both frame occurrence and variability. Crises generally create an opening for the formation of new perspectives and frames. These conditions provide an ideal test to see whether the focus of media reporting differs between online and print sources. We extract the dominant frames in almost 18,500 articles using machine-learning methods. While results indicate that many frames are, on average, more visible in either online or print media, these differences do not appear to follow a systematic logic. Regarding diversity of frame usage, we find that online media are, on average, more dominated by particular frames compared to print and that frame diversity is largely independent of important key events happening during our period of investigation.

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Na+-dependent phosphate transporters in the murine osteoclast: cellular distribution and protein interactions

AJP Cell Physiology ◽

10.1152/ajpcell.00580.2002 ◽

2003 ◽

Vol 284 (6) ◽

pp. C1633-C1644 ◽

Cited By ~ 37

Author(s):

Mohammed A. Khadeer ◽

Zhihui Tang ◽

Harriet S. Tenenhouse ◽

Maribeth V. Eiden ◽

Heini Murer ◽

...

Keyword(s):

Plasma Membrane ◽

Bone Resorption ◽

Protein Interactions ◽

Cellular Localization ◽

Fluorescent Protein ◽

Basolateral Membrane ◽

Atp Synthesis ◽

Cellular Distribution ◽

Green Fluorescent ◽

Carboxy Terminal

We previously demonstrated that inhibition of Na-dependent phosphate (Pi) transport in osteoclasts led to reduced ATP levels and diminished bone resorption. These findings suggested that Na/Picotransporters in the osteoclast plasma membrane provide Pifor ATP synthesis and that the osteoclast may utilize part of the Pireleased from bone resorption for this purpose. The present study was undertaken to define the cellular localization of Na/Picotransporters in the mouse osteoclast and to identify the proteins with which they interact. Using glutathione S-transferase (GST) fusion constructs, we demonstrate that the type IIa Na/Picotransporter (Npt2a) in osteoclast lysates interacts with the Na/H exchanger regulatory factor, NHERF-1, a PDZ protein that is essential for the regulation of various membrane transporters. In addition, NHERF-1 in osteoclast lysates interacts with Npt2a in spite of deletion of a putative PDZ-binding domain within the carboxy terminus of Npt2a. In contrast, deletion of the carboxy-terminal TRL amino acid motif of Npt2a significantly reduced its interaction with NHERF-1 in kidney lysates. Studies in osteoclasts transfected with green fluorescent protein-Npt2a constructs indicated that Npt2a colocalizes with NHERF-1 and actin at or near the plasma membrane of the osteoclast and associates with ezrin, a linker protein associated with the actin cytoskeleton, likely via NHERF-1. Furthermore, we demonstrate by RT/PCR of osteoclast RNA and in situ hybridization that the type III Na/Picotransporter, PiT-1, is also expressed in mouse osteoclasts. To examine the cellular distribution of PiT-1, we infected mouse osteoclasts with a retroviral vector encoding PiT-1 fused to an epitope tag. PiT-1 colocalizes with actin and is present on the basolateral membrane of the polarized osteoclast, similar to that previously reported for Npt2a. Taken together, our data suggest that association of Npt2a with NHERF-1, ezrin, and actin, and of PiT-1 with actin, may be responsible for membrane sorting and regulation of these Na/Picotransporters in the osteoclast.

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The unconventional biogenesis of Kv7.1-KCNE1 complexes

Science Advances ◽

10.1126/sciadv.aay4472 ◽

2020 ◽

Vol 6 (14) ◽

pp. eaay4472 ◽

Cited By ~ 1

Author(s):

Anna Oliveras ◽

Clara Serrano-Novillo ◽

Cristina Moreno ◽

Alicia de la Cruz ◽

Carmen Valenzuela ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Plasma Membrane ◽

Secretory Pathway ◽

Regulatory Subunit ◽

Long Qt ◽

Ongoing Debate ◽

Subcellular Compartment ◽

Ongoing Controversy ◽

The Subject ◽

Complex Forms

The potassium channel Kv7.1 associates with the KCNE1 regulatory subunit to trigger cardiac IKs currents. Although the Kv7.1/KCNE1 complex has received much attention, the subcellular compartment hosting the assembly is the subject of ongoing debate. Evidence suggests that the complex forms either earlier in the endoplasmic reticulum or directly at the plasma membrane. Kv7.1 and KCNE1 mutations, responsible for long QT syndromes, impair association and traffic, thereby altering IKs currents. We found that Kv7.1 and KCNE1 do not assemble in the first stages of their biogenesis. Data support an unconventional secretory pathway for Kv7.1-KCNE1 that bypasses Golgi. This route targets channels to endoplasmic reticulum–plasma membrane junctions, where Kv7.1-KCNE1 assemble. This mechanism helps to resolve the ongoing controversy about the subcellular compartment hosting the association. Our results also provide new insights into IKs channel localization at endoplasmic reticulum–plasma membrane junctions, highlighting an alternative anterograde trafficking mechanism for oligomeric ion channels.

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Silencing of Plasma Membrane Ca2+-ATPase Isoforms 2 and 3 Impairs Energy Metabolism in Differentiating PC12 Cells

BioMed Research International ◽

10.1155/2014/735106 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 5

Author(s):

Tomasz Boczek ◽

Malwina Lisek ◽

Bozena Ferenc ◽

Antoni Kowalski ◽

Magdalena Wiktorska ◽

...

Keyword(s):

Plasma Membrane ◽

Pc12 Cells ◽

Molecular Mechanisms ◽

Atp Synthesis ◽

Mitochondrial Activity ◽

Excitable Cells ◽

Close Link ◽

Atp Level ◽

Atp Generation

A close link between Ca2+, ATP level, and neurogenesis is apparent; however, the molecular mechanisms of this relationship have not been completely elucidated. Transient elevations of cytosolic Ca2+may boost ATP synthesis, but ATP is also consumed by ion pumps to maintain a low Ca2+in cytosol. In differentiation process plasma membrane Ca2+ATPase (PMCA) is considered as one of the major players for Ca2+homeostasis. From four PMCA isoforms, the fastest PMCA2 and PMCA3 are expressed predominantly in excitable cells. In the present study we assessed whether PMCA isoform composition may affect energy balance in differentiating PC12 cells. We found that PMCA2-downregulated cells showed higher basal O2consumption, lower NAD(P)H level, and increased activity of ETC. These changes associated with higher[Ca2+]cresulted in elevated ATP level. Since PMCA2-reduced cells demonstrated greatest sensitivity to ETC inhibition, we suppose that the main source of energy for PMCA isoforms 1, 3, and 4 was oxidative phosphorylation. Contrary, cells with unchanged PMCA2 expression exhibited prevalence of glycolysis in ATP generation. Our results with PMCA2- or PMCA3-downregulated lines provide an evidence of a novel role of PMCA isoforms in regulation of bioenergetic pathways, and mitochondrial activity and maintenance of ATP level during PC12 cells differentiation.

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