Relatedness and the evolution of mechanisms to divide labour in microorganisms

Mapping Intimacies ◽

10.22541/au.163250995.57930538/v1 ◽

2021 ◽

Author(s):

Ming Liu ◽

Stuart West ◽

Guy Cooper

Keyword(s):

Cell Signalling ◽

Simulation Models ◽

Division Of Labour ◽

Biochemical Reactions ◽

Previous Theory ◽

Random Fluctuations

Division of labour occurs when cooperating individuals specialise to perform different tasks. In bacteria and other microorganisms, some species divide labour by random specialisation, where an individual’s role is determined by random fluctuations in biochemical reactions within the cell. Other species divide labour by coordinating across individuals to determine which cells will perform which task, using mechanisms such as between-cell signalling. However, previous theory, examining the evolution of mechanisms to divide labour between reproductives and sterile helpers, has only considered clonal populations, where there is no potential for conflict between individuals. We used a mixture of analytical and simulation models to examine non-clonal populations and found that: (1) intermediate levels of coordination can be favoured, between the extreme of no coordination (random) and full coordination; (2) as relatedness decreases, coordinated division of labour is less likely to be favoured. Our results can help explain why coordinated division of labour is relatively rare in bacteria, where groups may frequently be non-clonal.

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Modelling cellular signalling systems

Essays in Biochemistry ◽

10.1042/bse0450083 ◽

2008 ◽

Vol 45 ◽

pp. 83-94 ◽

Cited By ~ 19

Author(s):

Padmini Rangamani ◽

Ravi Iyengar

Keyword(s):

Partial Differential Equations ◽

Differential Equations ◽

Mathematical Models ◽

Cell Signalling ◽

Computational Modelling ◽

Signalling Pathways ◽

Biochemical Reactions ◽

Building Models ◽

Stochastic Representations ◽

Signalling Systems

Cell signalling pathways and networks are complex and often non-linear. Signalling pathways can be represented as systems of biochemical reactions that can be modelled using differential equations. Computational modelling of cell signalling pathways is emerging as a tool that facilitates mechanistic understanding of complex biological systems. Mathematical models are also used to generate predictions that may be tested experimentally. In the present chapter, the various steps involved in building models of cell signalling pathways are discussed. Depending on the nature of the process being modelled and the scale of the model, different mathematical formulations, ranging from stochastic representations to ordinary and partial differential equations are discussed. This is followed by a brief summary of some recent modelling successes and the state of future models.

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Correlation of Pore Structure and Permeability by SEM-Image Analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180896 ◽

1990 ◽

Vol 48 (1) ◽

pp. 428-429

Author(s):

C. A. Callender ◽

Wm. C. Dawson ◽

J. J. Funk

Keyword(s):

Image Analysis ◽

Pore Structure ◽

Imaging System ◽

Pore Space ◽

Simulation Models ◽

Image Analyzer ◽

Imaging Data ◽

Sem Images ◽

Thin Sections ◽

Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

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Caveolin-1, galectin-3 and lipid raft domains in cancer cell signalling

Essays in Biochemistry ◽

10.1042/bse0570189 ◽

2015 ◽

Vol 57 ◽

pp. 189-201 ◽

Cited By ~ 13

Author(s):

Jay Shankar ◽

Cecile Boscher ◽

Ivan R. Nabi

Keyword(s):

Plasma Membrane ◽

Lipid Rafts ◽

Cancer Cell ◽

Cellular Response ◽

Spatial Organization ◽

Essential Feature ◽

Cell Signalling ◽

Coated Pits ◽

Signalling Molecules ◽

Raft Domains

Spatial organization of the plasma membrane is an essential feature of the cellular response to external stimuli. Receptor organization at the cell surface mediates transmission of extracellular stimuli to intracellular signalling molecules and effectors that impact various cellular processes including cell differentiation, metabolism, growth, migration and apoptosis. Membrane domains include morphologically distinct plasma membrane invaginations such as clathrin-coated pits and caveolae, but also less well-defined domains such as lipid rafts and the galectin lattice. In the present chapter, we will discuss interaction between caveolae, lipid rafts and the galectin lattice in the control of cancer cell signalling.

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Biophysics (and sociology) of ceramides.

Biochemical Society Symposium ◽

10.1042/bss0720177 ◽

2005 ◽

Vol 72 ◽

pp. 177-188 ◽

Cited By ~ 28

Author(s):

Félix M. Goñi ◽

F-Xabier Contreras ◽

L-Ruth Montes ◽

Jesús Sot ◽

Alicia Alonso

Keyword(s):

Cell Biology ◽

Positive Curvature ◽

Acyl Chain ◽

Cell Signalling ◽

Hexagonal Structure ◽

Lipid Monolayer ◽

Flip Flop ◽

Long Chain ◽

Bilayer Permeability

In the past decade, the long-neglected ceramides (N-acylsphingosines) have become one of the most attractive lipid molecules in molecular cell biology, because of their involvement in essential structures (stratum corneum) and processes (cell signalling). Most natural ceramides have a long (16-24 C atoms) N-acyl chain, but short N-acyl chain ceramides (two to six C atoms) also exist in Nature, apart from being extensively used in experimentation, because they can be dispersed easily in water. Long-chain ceramides are among the most hydrophobic molecules in Nature, they are totally insoluble in water and they hardly mix with phospholipids in membranes, giving rise to ceramide-enriched domains. In situ enzymic generation, or external addition, of long-chain ceramides in membranes has at least three important effects: (i) the lipid monolayer tendency to adopt a negative curvature, e.g. through a transition to an inverted hexagonal structure, is increased, (ii) bilayer permeability to aqueous solutes is notoriously enhanced, and (iii) transbilayer (flip-flop) lipid motion is promoted. Short-chain ceramides mix much better with phospholipids, promote a positive curvature in lipid monolayers, and their capacities to increase bilayer permeability or transbilayer motion are very low or non-existent.

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Genomic analysis of C-type lectins

Biochemical Society Symposium ◽

10.1042/bss0690059 ◽

2002 ◽

Vol 69 ◽

pp. 59-72 ◽

Cited By ~ 85

Author(s):

Kurt Drickamer ◽

Andrew J. Fadden

Keyword(s):

Biological Effects ◽

Cell Signalling ◽

Genomic Analysis ◽

Binding Activity ◽

Immunoglobulin Superfamily ◽

Carbohydrate Binding ◽

Carbohydrate Recognition ◽

Calcium Dependent ◽

Binding Domains ◽

Carbohydrate Recognition Domains

Many biological effects of complex carbohydrates are mediated by lectins that contain discrete carbohydrate-recognition domains. At least seven structurally distinct families of carbohydrate-recognition domains are found in lectins that are involved in intracellular trafficking, cell adhesion, cell–cell signalling, glycoprotein turnover and innate immunity. Genome-wide analysis of potential carbohydrate-binding domains is now possible. Two classes of intracellular lectins involved in glycoprotein trafficking are present in yeast, model invertebrates and vertebrates, and two other classes are present in vertebrates only. At the cell surface, calcium-dependent (C-type) lectins and galectins are found in model invertebrates and vertebrates, but not in yeast; immunoglobulin superfamily (I-type) lectins are only found in vertebrates. The evolutionary appearance of different classes of sugar-binding protein modules parallels a development towards more complex oligosaccharides that provide increased opportunities for specific recognition phenomena. An overall picture of the lectins present in humans can now be proposed. Based on our knowledge of the structures of several of the C-type carbohydrate-recognition domains, it is possible to suggest ligand-binding activity that may be associated with novel C-type lectin-like domains identified in a systematic screen of the human genome. Further analysis of the sequences of proteins containing these domains can be used as a basis for proposing potential biological functions.

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