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1.
Biosystems ; 233: 105020, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37716403

RESUMO

The problem of the origin of canonical and aberrant DNA mutations and the contribution of protons to genetic stability is an essential topic in molecular biology. Based on the empirical results, we reconsidered canonical and tautomeric mutations under the two-fluid model of quantum physics. We assumed that the pressure exerted by protons (H+) in the DNA environment, through changes in pH, could alter the concentration ratio of canonical and tautomeric base pairs, which were found to be different at and beyond the criticality level, respectively. We anticipate that the deviation of the cellular system from a specific (critical) temperature at which dynamic entropy reaches a minimum and a critical pH occurs could result in tautomerization and point mutations.

2.
Protoplasma ; 256(4): 1037-1049, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30834467

RESUMO

The topology of a cellular pattern, which means the spatial arrangement of cells, directly corresponds with cell packing, which is crucial for tissue and organ functioning. The topological features of cells that are typically analyzed are the number of their neighbors and the cell area. To date, the objects of most topological studies have been the growing cells of the surface tissues of plant and animal organs. Some of these researches also provide verification of Lewis's Law concerning the linear correlation between the number of neighboring cells and the cell area. Our aim was to analyze the cellular topology and applicability of Lewis's Law to an anisotropically growing plant organ. The object of our study was the root apex of radish. Based on the tensor description of plant organ growth, we specified the level of anisotropy in specific zones (the root proper, the columella of the cap and the lateral parts of the cap) and in specific types of both external (epidermis) and internal tissues (stele and ground tissue) of the apex. The strongest anisotropy occurred in the root proper, while both zones of the cap showed an intermediate level of anisotropy of growth. Some differences in the topology of the cellular pattern in the zones were also detected; in the root proper, six-sided cells predominated, while in the root cap columella and in the lateral parts of the cap, most cells had five neighbors. The correlation coefficient rL between the number of neighboring cells and the cell area was high in the apex as a whole as well as in all of the zones except the root proper and in all of the tissue types except the ground tissue. In general, Lewis's Law was fulfilled in the anisotropically growing radish root apex. However, the level of the applicability (rL value) of Lewis's Law was negatively correlated with the level of the anisotropy of growth, which may suggest that in plant organs in the regions of anisotropic growth, the number of neighboring cells is less dependent on the cell size.


Assuntos
Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento , Raphanus/citologia , Raphanus/crescimento & desenvolvimento , Anisotropia , Células Vegetais
4.
J Exp Bot ; 69(18): 4349-4362, 2018 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-29945239

RESUMO

The relatively thick primary walls of epidermal and collenchyma cells often form waviness on the surface that faces the protoplast when they are released from the tensile in-plane stress that operates in situ. This waviness is a manifestation of buckling that results from the heterogeneity of the elastic strain across the wall. In this study, this heterogeneity was confirmed by the spontaneous bending of isolated wall fragments that were initially flat. We combined the empirical data on the formation of waviness in growing cell walls with computations of the buckled wall shapes. We chose cylindrical-shaped organs with a high degree of longitudinal tissue stress because in such organs the surface deformation that accompanies the removal of the stress is strongly anisotropic and leads to the formation of waviness in which wrinkles on the inner wall surface are always transverse to the organ axis. The computations showed that the strain heterogeneity results from individual or overlaid gradients of pre-stress and stiffness across the wall. The computed wall shapes depend on the assumed wall thickness and mechanical gradients. Thus, a quantitative analysis of the wall waviness that forms after stress removal can be used to assess the mechanical heterogeneity of the cell wall.


Assuntos
Parede Celular/metabolismo , Helianthus/fisiologia , Hordeum/fisiologia , Taraxacum/fisiologia , Fenômenos Biomecânicos , Cotilédone/fisiologia , Módulo de Elasticidade , Hipocótilo/fisiologia
5.
Am J Bot ; 105(2): 257-265, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29578288

RESUMO

PREMISE OF THE STUDY: In numerous vascular plants, pavement cells of the leaf epidermis are shaped like a jigsaw-puzzle piece. Knowledge about the subcellular pattern of growth that accompanies morphogenesis of such a complex shape is crucial for studies of the role of the cytoskeleton, cell wall and phytohormones in plant cell development. Because the detailed growth pattern of the anticlinal and periclinal cell walls remains unknown, our aim was to measure pavement cell growth at a subcellular resolution. METHODS: Using fluorescent microbeads applied to the surface of the adaxial leaf epidermis of Arabidopsis thaliana as landmarks for growth computation, we directly assessed the growth rates for the outer periclinal and anticlinal cell walls at a subcellular scale. KEY RESULTS: We observed complementary tendencies in the growth pattern of the outer periclinal and anticlinal cell walls. Central portions of periclinal walls were characterized by relatively slow growth, while growth of the other wall portions was heterogeneous. Local growth of the periclinal walls accompanying lobe development after initiation was relatively fast and anisotropic, with maximal extension usually in the direction along the lobe axis. This growth pattern of the periclinal walls was complemented by the extension of the anticlinal walls, which was faster on the lobe sides than at the tips. CONCLUSIONS: Growth of the anticlinal and outer periclinal walls of leaf pavement cells is heterogeneous. The growth of the lobes resembles cell elongation via diffuse growth rather than tip growth.


Assuntos
Arabidopsis/citologia , Epiderme Vegetal/citologia , Folhas de Planta/citologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/ultraestrutura , Parede Celular/ultraestrutura , Microscopia de Fluorescência , Microesferas , Epiderme Vegetal/crescimento & desenvolvimento , Epiderme Vegetal/ultraestrutura , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/ultraestrutura
6.
Plant Methods ; 13: 110, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29238397

RESUMO

BACKGROUND: The development of cell pattern in the surface cell layer of the shoot apex can be investigated in vivo by use of a time-lapse confocal images, showing naked meristem in 3D in successive times. However, how this layer is originated from apical initials and develops as a result of growth and divisions of their descendants, remains unknown. This is an open area for computer modelling. A method to generate the surface cell layer is presented on the example of the 3D paraboloidal shoot apical dome. In the used model the layer originates from three apical initials that meet at the dome summit and develops through growth and cell divisions under the isotropic surface growth, defined by the growth tensor. The cells, which are described by polyhedrons, divide anticlinally with the smallest division plane that passes depending on the used mode through the cell center, or the point found randomly near this center. The formation of the surface cell pattern is described with the attention being paid to activity of the apical initials and fates of their descendants. RESULTS: The computer generated surface layer that included about 350 cells required about 1200 divisions of the apical initials and their derivatives. The derivatives were arranged into three more or less equal clonal sectors composed of cellular clones at different age. Each apical initial renewed itself 7-8 times to produce the sector. In the shape and location and the cellular clones the following divisions of the initial were manifested. The application of the random factor resulted in more realistic cell pattern in comparison to the pure mode. The cell divisions were analyzed statistically on the top view. When all of the division walls were considered, their angular distribution was uniform, whereas in the distribution that was limited to apical initials only, some preferences related to their arrangement at the dome summit were observed. CONCLUSIONS: The realistic surface cell pattern was obtained. The present method is a useful tool to generate surface cell layer, study activity of initial cells and their derivatives, and how cell expansion and division are coordinated during growth. We expect its further application to clarify the question of a number and permanence or impermanence of initial cells, and possible relationship between their shape and oriented divisions, both on the ground of the growth tensor approach.

7.
J Biol Phys ; 43(4): 461-470, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28900825

RESUMO

This paper presents a Fourier analysis of the Ortega equation that examines the growth dynamics of plants, specifically the pollen tubes or non-meristematic zones of elongating coleoptiles. A frequency-induced transition from highly nonlinear (periodical) growth-like the one observed in pollen tubes-to monotonically ascending and asymptotically saturated (sigmoid-like) growth, which is anticipated within the framework of a 'two-fluid model', is shown. A dynamic phase diagram is calculated and presented in the form of a live video clip.


Assuntos
Movimento Celular , Modelos Biológicos , Desenvolvimento Vegetal , Análise de Fourier , Células Vegetais/metabolismo , Tubo Polínico/citologia , Tubo Polínico/crescimento & desenvolvimento
8.
Elife ; 4: 05864, 2015 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-25946108

RESUMO

Morphogenesis emerges from complex multiscale interactions between genetic and mechanical processes. To understand these processes, the evolution of cell shape, proliferation and gene expression must be quantified. This quantification is usually performed either in full 3D, which is computationally expensive and technically challenging, or on 2D planar projections, which introduces geometrical artifacts on highly curved organs. Here we present MorphoGraphX ( www.MorphoGraphX.org), a software that bridges this gap by working directly with curved surface images extracted from 3D data. In addition to traditional 3D image analysis, we have developed algorithms to operate on curved surfaces, such as cell segmentation, lineage tracking and fluorescence signal quantification. The software's modular design makes it easy to include existing libraries, or to implement new algorithms. Cell geometries extracted with MorphoGraphX can be exported and used as templates for simulation models, providing a powerful platform to investigate the interactions between shape, genes and growth.


Assuntos
Algoritmos , Arabidopsis/ultraestrutura , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Software , Animais , Anisotropia , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Cassia/genética , Cassia/crescimento & desenvolvimento , Cassia/ultraestrutura , Proliferação de Células , Forma Celular , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/ultraestrutura , Flores/genética , Flores/crescimento & desenvolvimento , Flores/ultraestrutura , Frutas/genética , Frutas/crescimento & desenvolvimento , Frutas/ultraestrutura , Expressão Gênica , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Imageamento Tridimensional/instrumentação , Imageamento Tridimensional/estatística & dados numéricos , Solanum lycopersicum/genética , Solanum lycopersicum/crescimento & desenvolvimento , Solanum lycopersicum/ultraestrutura , Microscopia Confocal , Microtúbulos/genética , Microtúbulos/ultraestrutura , Morfogênese/genética , Desenvolvimento Vegetal/genética , Imagem com Lapso de Tempo/instrumentação , Imagem com Lapso de Tempo/métodos , Imagem com Lapso de Tempo/estatística & dados numéricos
9.
Ann Bot ; 114(5): 913-21, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25108392

RESUMO

BACKGROUND AND AIMS: Microscopic observations of lateral roots (LRs) in Arabidopsis thaliana reveal that the cross-sectional shape of the organ changes from its basal to its apical region. The founder cells for LRs are elongated along the parent root axis, and thus from the site of initiation the base of LRs resemble an ellipse. The circumference of the apical part of LRs is usually a circle. The objective of this study was to analyse the characteristics of changes in the growth field of LRs possessing various shapes in their basal regions. METHODS: The LRs of the wild type (Col-0) and two transgenic arabidopsis lines were analysed. On the basis of measurements of the long and short diameters (DL and DS, respectively) of the ellipse-like figure representing the bases of particular LRs, their asymmetry ratios (DL/DS) were determined. Possible differences between accessions were analysed by applying statistical methods. KEY RESULTS: No significant differences between accessions were detected. Comparisons were therefore made of the maximal, minimal and mean value of the ratio of all the LRs analysed. Taking into consideration the lack of circular symmetry of the basal part, rates of growth were determined at selected points on the surface of LRs by the application of the growth tensor method, a mathematical tool previously applied only to describe organs with rotational symmetry. Maps showing the distribution of growth rates were developed for surfaces of LRs of various asymmetry ratios. CONCLUSIONS: The maps of growth rates on the surfaces of LRs having various shapes of the basal part show differences in both the geometry and the manner of growth, thus indicating that the manner of growth of the LR primordium is correlated to its shape. This is the first report of a description of growth of an asymmetric plant organ using the growth tensor method. The mathematical modelling adopted in the study provides new insights into plant organ formation and shape.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Arabidopsis/citologia , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Genes Reporter , Modelos Teóricos , Raízes de Plantas/citologia , Raízes de Plantas/genética , Plantas Geneticamente Modificadas
10.
PLoS One ; 8(12): e84337, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24367654

RESUMO

Growth and cellular organization of the Arabidopsis root apex are investigated in various aspects, but still little is known about spatial and directional variation of growth rates in very apical part of the apex, especially in 3D. The present paper aims to fill this gap with the aid of a computer modelling based on the growth tensor method. The root apex with a typical shape and cellular pattern is considered. Previously, on the basis of two types of empirical data: the published velocity profile along the root axis and dimensions of cell packets formed in the lateral part of the root cap, the displacement velocity field for the root apex was determined. Here this field is adopted to calculate the linear growth rate in different points and directions. The results are interpreted taking principal growth directions into account. The root apex manifests a significant anisotropy of the linear growth rate. The directional preferences depend on a position within the root apex. In the root proper the rate in the periclinal direction predominates everywhere, while in the root cap the predominating direction varies with distance from the quiescent centre. The rhizodermis is distinguished from the neighbouring tissues (cortex, root cap) by relatively high contribution of the growth rate in the anticlinal direction. The degree of growth anisotropy calculated for planes defined by principal growth directions and exemplary cell walls may be as high as 25. The changes in the growth rate variation are modelled.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Modelos Biológicos , Raízes de Plantas/crescimento & desenvolvimento , Anisotropia , Arabidopsis/citologia , Parede Celular/metabolismo , Cinética , Raízes de Plantas/citologia , Análise Espacial
11.
C R Biol ; 336(9): 425-32, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24161239

RESUMO

Plant organs grow in coordinated and continuous way. Such growth is of a tensor nature, hence there is an infinite number of different directions of growth rate in each point of the growing organ. Three mutually orthogonal directions of growth can be recognized in which growth achieves extreme values (principal directions of growth [PDGs]). Models based on the growth tensor have already been successfully applied to the root and shoot apex. This paper presents the 2D model of growth applied to the arabidopsis leaf. The model employs the growth tensor method with a non-stationary velocity field. The postulated velocity functions are confirmed by growth measurements with the aid of the replica method.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Simulação por Computador , Modelos Biológicos , Folhas de Planta/crescimento & desenvolvimento , Fenômenos Biomecânicos
12.
PLoS One ; 7(11): e48087, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23144847

RESUMO

Pollen tubes are extremely rapidly growing plant cells whose morphogenesis is determined by spatial gradients in the biochemical composition of the cell wall. We investigate the hypothesis (MP) that the distribution of the local mechanical properties of the wall, corresponding to the change of the radial symmetry along the axial direction, may lead to growth oscillations in pollen tubes. We claim that the experimentally observed oscillations originate from the symmetry change at the transition zone, where both intervening symmetries (cylindrical and spherical) meet. The characteristic oscillations between resonating symmetries at a given (constant) turgor pressure and a gradient of wall material constants may be identified with the observed growth-cycles in pollen tubes.


Assuntos
Tubo Polínico/citologia , Algoritmos , Fenômenos Biomecânicos , Parede Celular/fisiologia , Modelos Biológicos , Tubo Polínico/anatomia & histologia , Tubo Polínico/crescimento & desenvolvimento , Tubo Polínico/fisiologia , Estresse Fisiológico
13.
Planta ; 236(5): 1547-57, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22828709

RESUMO

In angiosperms, growth of the root apex is determined by the quiescent centre. All tissues of the root proper and the root cap are derived from initial cells that surround this zone. The diversity of cell lineages originated from these initials suggests an interesting variation of the displacement velocity within the root apex. However, little is known about this variation, especially in the most apical region including the root cap. This paper shows a method of determination of velocity field for this region taking the Arabidopsis root apex as example. Assuming the symplastic growth without a rotation around the root axis, the method combines mathematical modelling and two types of empirical data: the published velocity profile along the root axis above the quiescent centre, and dimensions of cell packet originated from the initials of epidermis and lateral root cap. The velocities, calculated for points of the axial section, vary in length and direction. Their length increases with distance from the quiescent centre, in the root cap at least twice slower than in the root proper, if points at similar distance from the quiescent centre are compared. The vector orientation depends on the position of a calculation point, the widest range of angular changes, reaching almost 90°, in the lateral root cap. It is demonstrated how the velocity field is related to both distribution of growth rates and growth-resulted deformation of the cell wall system. Also changes in the field due to cell pattern asymmetry and differences in slope of the velocity profile are modelled.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Modelos Biológicos , Raízes de Plantas/crescimento & desenvolvimento , Linhagem da Célula , Parede Celular , Modelos Teóricos , Coifa/crescimento & desenvolvimento , Raízes de Plantas/citologia
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