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Bezzi, Michele; Ciliberto, Andrea; Mengoni, Alessio

doi:10.1023/a:1005192817264

Cited by 6 publications

(4 citation statements)

References 14 publications

(21 reference statements)

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“…Filamentous fungi grow by the polarised extension of thread-like hyphae, which make up the body, or mycelium, of a fungus. Except for branching (which initiates new hyphae) the site of growth is localised to a single region at the tip of each elongating hypha.There are many theoretical models for the growth of fungal colonies and of single hyphae (reviewed in [2,3]). Most models of single hypha growth concentrate on biomechanics [4,5].…”

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Model of hyphal tip growth involving microtubule-based transport

et al. 2007

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We propose a simple model for mass transport within a fungal hypha and its subsequent growth. Inspired by the role of microtubule-transported vesicles, we embody the internal dynamics of mass inside a hypha with mutually excluding particles progressing stochastically along a growing onedimensional lattice. The connection between long range transport of materials for growth, and the resulting extension of the hyphal tip has not previously been addressed in the modelling literature. We derive and analyse mean-field equations for the model and present a phase diagram of its steady state behaviour, which we compare to simulations. We discuss our results in the context of the filamentous fungus, Neurospora crassa. PACS numbers: 87.10.+e, 87.16.Ac, 87.16.Ka , Biologically, fungi are distinct from both plants and animals. In addition to their intrinsic interest, they impact immensely on human affairs and on the ecosystem [1].Key to the evolutionary success of fungi, is their unique mode of growth. Filamentous fungi grow by the polarised extension of thread-like hyphae, which make up the body, or mycelium, of a fungus. Except for branching (which initiates new hyphae) the site of growth is localised to a single region at the tip of each elongating hypha.There are many theoretical models for the growth of fungal colonies and of single hyphae (reviewed in [2,3]). Most models of single hypha growth concentrate on biomechanics [4,5]. Of more interest for us here is the "vesicle supply centre" (VSC) model [6,7], in which raw materials for growth are packaged in secretory vesicles and distributed to the hyphal surface from a single "supply centre" (often identified with an organelle complex known as the Spitzenkörper, or apical body [8,9]) situated within the growing tip. This model is capable of predicting the shape of hyphal tips; but the speed of growth (equivalent to the speed of the VSC) is an input parameter. Moreover, all transport processes are subsumed into a single rate of vesicle supply at the VSC. We are aware of just one model that takes explicit account of transport along the growing hypha [10]. A major interest of this early work, however, was the initiation of branching; these authors did not relate vesicle transport to growth velocity. This latter issue remains poorly understood.In this work, we propose a simple one-dimensional model which makes an explicit connection between the long-distance transport of building materials along a hypha and the resulting extension as they are delivered to its apical site of growth.It is a highly idealised model, encompassing many complicated biological processes (many of which are still poorly understood) with two key parameters: the rate at which vesicles enter the system and the efficiency with which they extend the length of the hypha. We demonstrate that by altering these rates, steady states can be attained whereby the hypha is extending at a constant speed while being supplied with materials far behind the tip. Our model has features in common with [10]. Like [10], we...

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“…There are many theoretical models for the growth of fungal colonies and of single hyphae (reviewed in [2,3]). Most models of single hypha growth concentrate on biomechanics [4,5].…”

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Model of hyphal tip growth involving microtubule-based transport

et al. 2007

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“…It should be pointed out that the formation of such banded texture is well documented in polymer liquid crystals [26,27] and biological systems. [29] We shall now examine the system corresponding to the initial volume fractions at point B (f 1 ¼ 0:20, f 2 ¼ 0:50, f 3 ¼ 0:30) as depicted in Figure 1 having different solvent (a 2;0 L 23 ¼ À0:01) and non-solvent (a 3;0 L 23 ¼ 0:001) diffusivities. Figure 3 shows the spatio-temporal evolution of the fiber structure, exhibiting the smooth fiber surface with the microfibrillar structure in the core.…”

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confidence: 99%

Morphology Development in Polymer Fibers undergoing Solvent/Non‐solvent Exchange

Dayal

Kyu

2007

Macromolecular Symposia

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The solvent/non-solvent interchange across the fiber surface affects the morphology of the fiber in various ways. In this paper, simulations have been performed to elucidate the diverse morphologies obtained during spinning of polymer fibers under the presence of a non-solvent. The proposed model deals with a ternary system derived from Cahn-Hilliard equation, alternatively known as Time Dependent Ginzburg Landau-TDGL model B equation, involving the spatio-temporal evolution of concentration order parameter. Depending on the coexistence region of the ternary phase diagram, various fiber morphologies including concentric bands, internal microfibrillar structures, and porous structures were discerned. It may be inferred that the formation of the aforementioned diverse morphologies is a direct consequence of the initial conditions of the starting mixtures in a manner governed by the relative rates of solvent/non-solvent exchange and the dynamics of phase separation.

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“…The rate of extension, in a favorable environment, can be extremely rapid, up to 40 micrometers per minute. Many bio-physical models [2][3][4][5][6] describing the growth of fungal colonies and/or single hypha have been studied. In this context, efforts focused on the non-equilibrium properties of a modification of the totally asymmetric exclusion process (TASEP), by considering a distinct dynamics of one of the two boundary sites [7][8][9][10][11].…”

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Dynamical phase transition of a one-dimensional transport process including death

2010

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Motivated by biological aspects related to fungus growth, we consider the competition of growth and corrosion. We study a modification of the totally asymmetric exclusion process, including the probabilities of injection ␣ and death of the last particle ␦. The system presents a phase transition at ␦ c ͑␣͒, where the average position of the last particle ͗L͘ grows as ͱ t. For ␦ Ͼ ␦ c , a nonequilibrium stationary state exists while for ␦ Ͻ ␦ c the asymptotic state presents a low density and max current phases. We discuss the scaling of the density and current profiles for parallel and sequential updates. DOI: 10.1103/PhysRevE.81.042101 PACS number͑s͒: 05.40.Ϫa, 87.10.Hk, 87.10.Rt Fungi are eukaryotic organisms that include microorganisms such as yeasts and molds, as well as the familiar mushrooms. The growth of a fungus is formed by the combination of the apical growth and the branching process which leads to the development of a mycelium. Most of them grow as hyphae, which are a cylindrical thread-like structures of 5 -10 m in diameter and up to several centimeters in length ͓1͔. The apical growth is a quasi-one-dimensional process that extends the hypha by transport of material from the seed to the front tip. At this later position, enzymes are released into the environment, where the new wall material is synthesized. The rate of extension, in a favorable environment, can be extremely rapid, up to 40 m per minute. Many biophysical models ͓2-6͔ describing the growth of fungal colonies and/or single hypha have been studied. In this context, efforts focused on the nonequilibrium properties of a modification of the totally asymmetric exclusion process ͑TASEP͒, by considering a distinct dynamics of one of the two boundary sites ͓7-11͔.An important aspect not taken into account yet, is that fungi have the ability to grow in a wide range of habitats, including extreme environments ͓12-14͔ and survive intense UV/cosmic radiation during space travel ͓15͔. Since the wall of the tip is usually structurally weak ͓1͔, in such a situation the extension rate can be slowed down and as the hypha is progressively aging, it may break down or be broken by other organisms ͓1͔. Our analysis is focused on the theoretical description of the above-mentioned growing process in competition with a corrosive environment. The theoretical model used is based on a simple modification of the TASEP and captures the general behavior induced by the two competing processes.Proposed in 1968 to study the motion of ribosomes along mRNA ͓16,17͔, numerous modifications of the TASEP were introduced including multilane systems and multi species transport ͓18-22͔, Langmuir dynamics ͓23-25͔, extended particles ͓26,27͔ as well as systems with finite resources ͓28,29͔. In a general framework, such models are considered as toy models of transport phenomena in order to better understands physics far from equilibrium.In the first part of this Brief Report we define the model and the system parameters. After a careful definition of the parallel update dynami...

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Cited by 6 publications

References 14 publications

Model of hyphal tip growth involving microtubule-based transport

Model of hyphal tip growth involving microtubule-based transport

Morphology Development in Polymer Fibers undergoing Solvent/Non‐solvent Exchange

Dynamical phase transition of a one-dimensional transport process including death

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