On the nature of the earliest known lifeforms

AbstractOldest known microfossils were known to have the most complex of morphologies among prokaryotes. Given the morphology of an organism is governed by information encoded in its genome, it was proposed that these primitive organisms most likely possessed complex molecular biological processes. Here we worked with bacterial protoplasts under environmental conditions of Archaean earth and reproduced morphologies of every known microfossil and associated structures. Contrary to the current presumption, our work suggest that complex morphologies of these microfossils could be explained not by presence but by complete absence of molecular biological mechanisms. Environmental conditions and architecture of the cell membrane are the only factors that determined the morphology of these organisms. Based on our observations we present a case for reinterpretation of Archaean microfossils as protocells that were devoid of complex molecular biological processes rather than annotating them to a particular phylogenetic group of extant bacteria.One Sentence SummaryMicrofossils reported from Archaean BIF’s most likely were liposome like protocells, which had evolved mechanisms for energy conservation, but not for regulating cell morphology and replication.

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Biophysics and Modeling of Mechanotransduction in Neurons: A Review

Mathematics ◽

10.3390/math9040323 ◽

2021 ◽

Vol 9 (4) ◽

pp. 323

Author(s):

Martina Nicoletti ◽

Letizia Chiodo ◽

Alessandro Loppini

Keyword(s):

Ion Channels ◽

Cell Membrane ◽

Sensory Neurons ◽

Neuronal Cell ◽

Molecular Processes ◽

Biological Mechanisms ◽

Mechanosensitive Ion Channels ◽

Complex Interactions ◽

Different Types ◽

Intracellular Organelles

Mechanosensing is a key feature through which organisms can receive inputs from the environment and convert them into specific functional and behavioral outputs. Mechanosensation occurs in many cells and tissues, regulating a plethora of molecular processes based on the distribution of forces and stresses both at the cell membrane and at the intracellular organelles levels, through complex interactions between cells’ microstructures, cytoskeleton, and extracellular matrix. Although several primary and secondary mechanisms have been shown to contribute to mechanosensation, a fundamental pathway in simple organisms and mammals involves the presence of specialized sensory neurons and the presence of different types of mechanosensitive ion channels on the neuronal cell membrane. In this contribution, we present a review of the main ion channels which have been proven to be significantly involved in mechanotransduction in neurons. Further, we discuss recent studies focused on the biological mechanisms and modeling of mechanosensitive ion channels’ gating, and on mechanotransduction modeling at different scales and levels of details.

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Dynamical Analysis of bantam-Regulated Drosophila Circadian Rhythm Model

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127414501612 ◽

2014 ◽

Vol 24 (12) ◽

pp. 1450161 ◽

Cited By ~ 1

Author(s):

Ying Li ◽

Zengrong Liu

Keyword(s):

Circadian Rhythm ◽

Crucial Role ◽

Target Genes ◽

Classical Model ◽

Dynamical Analysis ◽

Biological Processes ◽

Biological Mechanisms ◽

Environmental Perturbations ◽

Dynamical Behaviors ◽

Important Regulator

MicroRNAs (miRNAs) interact with 3′untranslated region (UTR) elements of target genes to regulate mRNA stability or translation, and play a crucial role in regulating many different biological processes. bantam, a conserved miRNA, is involved in several functions, such as regulating Drosophila growth and circadian rhythm. Recently, it has been discovered that bantam plays a crucial role in the core circadian pacemaker. In this paper, based on experimental observations, a detailed dynamical model of bantam-regulated circadian clock system is developed to show the post-transcriptional behaviors in the modulation of Drosophila circadian rhythm, in which the regulation of bantam is incorporated into a classical model. The dynamical behaviors of the model are consistent with the experimental observations, which shows that bantam is an important regulator of Drosophila circadian rhythm. The sensitivity analysis of parameters demonstrates that with the regulation of bantam the system is more sensitive to perturbations, indicating that bantam regulation makes it easier for the organism to modulate its period against the environmental perturbations. The effectiveness in rescuing locomotor activity rhythms of mutated flies shows that bantam is necessary for strong and sustained rhythms. In addition, the biological mechanisms of bantam regulation are analyzed, which may help us more clearly understand Drosophila circadian rhythm regulated by other miRNAs.

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Non-axisymmetric shapes of biological membranes from locally induced curvature

10.1101/688127 ◽

2019 ◽

Cited By ~ 1

Author(s):

Yannick A. D. Omar ◽

Amaresh Sahu ◽

Roger A. Sauer ◽

Kranthi K. Mandadapu

Keyword(s):

Phase Separation ◽

Cell Membrane ◽

Viscous Flow ◽

Lipid Bilayers ◽

Biological Membranes ◽

Rate Of Change ◽

Computational Studies ◽

Biological Processes ◽

Resting Tension ◽

Physical Phenomena

In various biological processes such as endocytosis and caveolae formation, the cell membrane is locally deformed into curved configurations. Previous theoretical and computational studies to understand membrane morphologies resulting from locally induced curvature are often limited to axisymmetric shapes, which severely restricts the physically admissible morphologies. Under the restriction of axisymmetry, past efforts predict that the cell membrane buds at low resting tensions and stalls at a flat pit at high resting tensions. In this work, we lift the restriction of axisymmetry by employing recent theoretical and numerical advances to understand arbitrarily curved and deforming lipid bilayers. Our non-axisymmetric morphologies reveal membrane morphologies which agree well with axisymmetric studies—however only if the resting tension of the membrane is low. When the resting tension is moderate to high, we show that (i) axisymmetric invaginations are unstable; and (ii) non-axisymmetric ridge-shaped structures are energetically favorable. We further study the dynamical effects resulting from the interplay between intramembrane viscous flow and induced curvature, and find the rate at which the locally induced curvature increases is a key determinant in the formation of ridges. In particular, we show that axisymmetric buds are favored when the induced curvature is rapidly increased, while non-axisymmetric ridges are favored when the curvature is slowly increased: The rate of change of induced curvature affects the intramembrane viscous flow of lipids, which can impede the membrane’s ability to transition into ridges. We conclude that the appearance of non-axisymmetric ridges indicates that axisymmetry cannot be generally assumed when understanding processes involving locally induced curvature. Our results hold potentially relevant implications for biological processes such as endocytosis, and physical phenomena like phase separation in lipid bilayers.

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Intrinsic concentration cycles and high ion fluxes in self-assembled precipitate membranes

Interface Focus ◽

10.1098/rsfs.2019.0064 ◽

2019 ◽

Vol 9 (6) ◽

pp. 20190064 ◽

Cited By ~ 1

Author(s):

Yang Ding ◽

Julyan H. E. Cartwright ◽

Silvana S. S. Cardoso

Keyword(s):

Cell Membrane ◽

Fluid Mechanics ◽

Ion Channel ◽

Hydrothermal Vents ◽

Biological Processes ◽

Biological Cell ◽

Osmotic Flow ◽

Building Components ◽

Self Assembled ◽

Emergence Of Life

Concentration cycles are important for bonding of basic molecular building components at the emergence of life. We demonstrate that oscillations occur intrinsically in precipitation reactions when coupled with fluid mechanics in self-assembled precipitate membranes, such as at submarine hydrothermal vents. We show that, moreover, the flow of ions across one pore in such a prebiotic membrane is larger than that across one ion channel in a modern biological cell membrane, suggesting that proto-biological processes could be sustained by osmotic flow in a less efficient prebiotic environment. Oscillations in nanoreactors at hydrothermal vents may be just right for these warm little pores to be the cradle of life.

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Exploiting the biological response of two Serratia fonticola strains to the critical metals, gallium and indium

Scientific Reports ◽

10.1038/s41598-020-77447-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Joana B. Caldeira ◽

Paula V. Morais ◽

Rita Branco

Keyword(s):

Oxidative Stress ◽

Reduced Glutathione ◽

Biological Response ◽

High Tech ◽

Biological Processes ◽

Biological Mechanisms ◽

Critical Metals ◽

Sod Activity ◽

Stress Control ◽

Resistant Strains

AbstractThe use of microorganisms that allows the recovery of critical high-tech elements such as gallium (Ga) and indium (In) has been considered an excellent eco-strategy. In this perspective, it is relevant to understand the strategies of Ga and In resistant strains to cope with these critical metals. This study aimed to explore the effect of these metals on two Ga/In resistant strains and to scrutinize the biological processes behind the oxidative stress in response to exposure to these critical metals. Two strains of Serratia fonticola, A3242 and B2A1Ga1, with high resistance to Ga and In, were submitted to metal stress and their protein profiles showed an overexpressed Superoxide Dismutase (SOD) in presence of In. Results of inhibitor-protein native gel incubations identified the overexpressed enzyme as a Fe-SOD. Both strains exhibited a huge increase of oxidative stress when exposed to indium, visible by an extreme high amount of reactive oxygen species (ROS) production. The toxicity induced by indium triggered biological mechanisms of stress control namely, the decrease in reduced glutathione/total glutathione levels and an increase in the SOD activity. The effect of gallium in cells was not so boisterous, visible only by the decrease of reduced glutathione levels. Analysis of the cellular metabolic viability revealed that each strain was affected differently by the critical metals, which could be related to the distinct metal uptakes. Strain A3242 accumulated more Ga and In in comparison to strain B2A1Ga1, and showed lower metabolic activity. Understanding the biological response of the two metal resistant strains of S. fonticola to stress induced by Ga and In will tackle the current gap of information related with bacteria-critical metals interactions.

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Characterization of the Fracture Energy of a PFCB/PVDF Polymer Electrolyte Fuel Cell Membrane Using a Knife Slit Test

ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2012-91352 ◽

2012 ◽

Author(s):

Ashley R. Gordon ◽

Michael W. Ellis ◽

David A. Dillard ◽

Scott W. Case ◽

Robert B. Moore ◽

...

Keyword(s):

Fuel Cell ◽

Relative Humidity ◽

Cell Membrane ◽

Fracture Energy ◽

Polymer Electrolyte ◽

Polymer Blend ◽

Environmental Conditions ◽

Polyvinylidene Fluoride ◽

Polymer Electrolyte Fuel Cell ◽

Fracture Tests

Polymer electrolyte membranes (PEM) undergo hygrothermal stress cycling in an operating fuel cell which may lead to pinhole or crack formation and propagation resulting in membrane failure. The fracture energy of a material, measured by fracture tests, is the energy needed for a crack to propagate throughout the material. In this study, the fracture energy of a promising novel fuel cell membrane comprised of a blend of a sulfonated perfluorocyclobutane (PFCB) block copolymer and polyvinylidene fluoride (PVDF) is investigated in various environmental conditions using a knife slit test. Fracture energies determined using the knife slit test have been shown to be several orders of magnitude lower, and therefore closer to the intrinsic fracture energy of a material, than those found by other fracture tests of related membranes. It is believed that the intrinsic fracture energy can give insight into the fracture resistance and durability of the polymer blend membrane. A polymer blend of 70% PFCB and 30% PVDF was tested at dry and nominally 10% relative humidity conditions at 40, 70, and 90°C, as well as at 70°C and nominally 50% relative humidity, to assess the effect of environmental conditions on fracture energy. Results show that the PFCB/PVDF blend had comparable fracture energy to a baseline fuel cell material, Nafion® NRE 211. In addition, the fracture energy of the blend was found to lie between that of the PFCB and PVDF components.

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Darwinian Uncertainty

KronoScope ◽

10.1163/156852403322849251 ◽

2003 ◽

Vol 3 (2) ◽

pp. 217-225 ◽

Cited By ~ 1

Author(s):

Ralph Greenspan

Keyword(s):

Biological Processes ◽

Biological Mechanisms ◽

Contrasting View

AbstractReductionistic explanations in biology generally assume that biological mechanisms are highly deterministic. A contrasting view has emerged recently that takes into account the degeneracy of biological processes- the ability to arrive at a given endpoint by a variety of available paths- and pays particular attention to the role of history and contingency in biology.

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The concept of translocational regulation

The Journal of Cell Biology ◽

10.1083/jcb.200804157 ◽

2008 ◽

Vol 182 (2) ◽

pp. 225-232 ◽

Cited By ~ 81

Author(s):

Ramanujan S. Hegde ◽

Sang-Wook Kang

Keyword(s):

Endoplasmic Reticulum ◽

Membrane Protein ◽

Conceptual Framework ◽

Environmental Conditions ◽

Protein Translocation ◽

Regulatory Control ◽

Biological Processes ◽

Mechanistic Understanding

Biological processes are regulated to provide cells with exquisite adaptability to changing environmental conditions and cellular demands. The mechanisms regulating secretory and membrane protein translocation into the endoplasmic reticulum (ER) are unknown. A conceptual framework for translocational regulation is proposed based on our current mechanistic understanding of ER protein translocation and general principles of regulatory control.

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Antitumor Effect of IL-2 and TRAIL Proteins Expressed by Recombinant Salmonella in Murine Bladder Cancer Cells

Cellular Physiology and Biochemistry ◽

10.33594/000000398 ◽

2021 ◽

Vol 55 (4) ◽

pp. 460-476

Keyword(s):

Oxidative Stress ◽

Bladder Cancer ◽

Cell Membrane ◽

Cell Viability ◽

Cancer Cells ◽

Cell Morphology ◽

Antitumor Effect ◽

Interleukin 2 ◽

Continuous Increase ◽

Bladder Cancer Cells

Background/Aims: Cancer is the second most deadly disease in the world. The bladder cancer is one of the most aggressive types and shows a continuous increase in the number of cases. The use of bacteria as live vectors to deliver molecules directly to the tumor is a promising tool and has been used as an adjuvant treatment against several types of cancer. The aim of this study was to investigate the antitumor effect of Interleukin 2 (IL-2), TNF-related apoptosis-inducing ligand (TRAIL) and protein MIX against murine bladder cancer cells, lineage MB49. Methods: The attenuated Salmonella strain SL3261 was transformed by inserting the IL-2 and TRAIL genes. The effects of proteins on cell viability (MTT method), cell morphology (optical microscopy), cell recovery (clonogenic assay), cell membrane (lactate dehydrogenase release - LDH), on oxidative stress pathway (levels of nitric oxide, NO) and apoptosis (flow cytometry and high resolution epifluorescence images) were evaluated at intervals of 24 and 48 hours of action. Results: The results showed that there was a decrease in cell viability via damage to the cell membrane, alteration of cell morphology, non-recovery of cells, increase in the production of NO and incubate for of cells in the state of apoptosis in the two periods analyzed. Conclusion: The data presented suggest that IL-2, TRAIL and their MIX proteins in MB49 cells have cytotoxic potential and that this is associated with oxidative stress and apoptosis pathways. These results may contribute to the development of new therapeutic strategies for bladder cancer.

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Integrated in-depth bioinformatic analysis suggests RELCH/KIAA1468, LINC02341, and AKAP11 as candidate genes for ages at menarche and menopause

RESEARCH RESULTS IN BIOMEDICINE ◽

10.18413/2658-6533-2021-7-3-0-2 ◽

2021 ◽

Vol 7 (3) ◽

pp. 220-231

Author(s):

Volodymyr Dvornyk ◽

Keyword(s):

Lipid Metabolism ◽

Cell Survival ◽

Candidate Genes ◽

Bioinformatic Analysis ◽

Age At Menarche ◽

Biological Processes ◽

Genetic Associations ◽

Biological Mechanisms ◽

Natural Menopause ◽

Online Databases

Polymorphisms of the TNFRSF11A and TNFSF11 genes were reported for their association with age at menarche (AAM) and age at natural menopause (ANM). However, the biological mechanisms underlying this association remain largely unclear. The aim of the study: This study was to determine biological processes backing the observed genetic associations. Materials and methods: Fortyfour SNPs were analyzed using in silico approach and ten publicly available online databases and tools. Results: TNFRSF11A and TNFSF11 are highly pleiotropic genes that play a role in many metabolic processes. However, among that variety, lipid metabolism and cell survival and apoptosis seem the most biologically plausible mechanisms, through which these genes contribute to AAM and ANM. The analysis identified several mechanisms underlying the previously determined association of the TNFRSF11A and TNFSF11 genes with AAM and ANM and suggested RELCH/KIAA1468, LINC02341, and AKAP11 as new candidate genes for the traits.

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