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1

Anchorage-dependent chick embryo fibroblasts synthesise DNA and proliferate when cultured in multilayered sheets suspended among glass fibres

100%
Czyz J., Dobrucki J., Korohoda W.
Folia Biologica
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2001
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vol. 49
|
issue 1-2
1-12
EN
Chick embryo fibroblasts (CEFs) spontaneously form multicellular and multilayered sheets suspended on the network of glass fibres which are stabilized by fibronectin containing protein deposits located at cell-to-cell contacts. The cells situated within the sheets are surrounded by the neighbouring cells and their mechanical equilibrium is stabilised by intercellular ?parabaric? effects. It was found that CEFs in the sheets retain relatively high mitotic activity corresponding to that observed in sparse monolayer cultures. These cells grew up to much higher local density than in confluent and contact-inhibited monolayer cultures and developed an abundance of microfilament bundles that terminated at vinculin-containing protein complexes. The results presented demonstrate that direct contact with solid substratum, cell-to-cell contacts, local cell density, and intercellular exchange of humoral factors are not directly involved in the density-dependent inhibition of growth observed in monolayer cultures. They also support the concepts concerning the role of mechanical equilibrium of cell membrane and sub-membranous cytoskeleton in the regulation of proliferation of non-transformed cells.
2

Spreading-independent growth of normal fibroblasts in three-dimensional cultures

100%
Czyz J., Rajwa B., Bzowska M., Dobrucki J., Korohoda W.
Folia Biologica
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2004
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vol. 52
|
issue 1-2
19-24
EN
Changes of cell shape resulting from cellular flattening on culture substratum have previously been demonstrated to correlate with mitotic activity of normal animal cells in monolayer cultures. Here, we compared the shapes and proliferation of chick embryo fibroblasts cultured either in multicellular, multilayered sheets extended between glass fibres, or in standard monolayers. Fibroblasts in sheets retained the mitotic activity characteristic of that observed in sparse monolayer cultures, i.e. considerably higher that in confluent monolayers. Morphometric analyses revealed, however, that the cells in sheets were considerably less flattened than in monolayer cultures. These observations indicate that the modulation of culture conditions resulting in multidirectional cell stretching leads to the dissociation of flattening and mitotic activity of normal animal cells, so long as an intracellular stress field, generated by contractile cytoskeleton and stabilised by intercellular contacts, is maintained.
3
Content available remote

Structure of cytomatrix and nuclear matrix revealed by embedment-free electron microscopy

100%
Gajkowska B., Cholewinski M., Gniadecki R.
Acta Neurobiologiae Experimentalis
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2000
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vol. 60
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issue 2
147-158
EN
Embedment-free electron microscopy (EFEM) is a new method which allows the visualisation of cytoskeleton in whole-mounted cells. In this study we employed EFEM to investigate the structure of cellular scaffolds in glioma C6 cell line. The cells were extracted with Triton X-100 that dissolves phospholipids in the membranes and removes most of cytoplasmic soluble proteins. The DNA and nuclear histones were removed with DNase I and high-salt buffer, respectively. The remaining cellular frameworks were temporary embedded in diethylene glycol distearate (DGD), sectioned and observed in transmission and scanning electron microscope after the removal of DGD. The predominant structure was the extensive meshwork of 10-20 nm filaments in the cytoplasm (cytomatrix) and 15-30 nm filaments in the nucleus (nuclear matrix). The 5 nm filaments, presumably corresponding to the actin filaments, were present in the cytomatrix, but not in the nuclear matrix. Moreover, the ultrathin (3 nm) filaments, connecting other cytoskeletal components were detected. Those are possibly identical with the previously described plectin filaments. For the first time we report the occurrence of ultrathin filaments in the nuclear matrix. Thus, in a addition to the well known cytoskeletal components (microtubules, intermediate filaments, actin microfilaments) EFEM showed a new type of filaments (the ultrathin filaments) in the cytomatrix and nuclear matrix. Further immunocytochemical studies are needed to determine the biochemical identity of the filaments observed in EFEM.
4

Involvement of cytoskeleton in orientation of cell division in contact guided cells

100%
Krzysiek-Maczka G., Michalik M., Madeja Z., Korohoda W.
Folia Biologica
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2010
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vol. 58
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issue 1-2
21-27
EN
Single human skin fibroblasts and the skin keratinocyte cell line HaCaT show contact guidance and elongate along narrow (1-2 Fm) scratches in glass substratum. During cell division these cells orientate their mitotic spindles along the long axis of the cell. Immunofluorescence staining of actin, tubulin, chromatin, and the nuclear NuMA protein complex demonstrated that cell elongation along scratches is accompanied by a corresponding rearrangement in the cytoskeleton. The results and literature suggest the following steps in the interplay between outside-in and inside-out signalling in the regulation of cell division orientation by extracellular factors. The interaction of cell surface with an anisotropy in the local environment causes changes in F-actin organization, cell elongation and alignment of stress fibres along the cell axis. This is accompanied by a corresponding reorientation of microtubules. Microtubules mediate between cell shape changes dependent upon cell interaction with substratum or other cells, the cortical actin and the position of centrosomes. Centrosomes determine the position and orientation of the mitotic spindle. The astral and central microtubules of the mitotic spindle control the localization of contraction-relaxation in the cell cortex and the position of the constriction ring and cell division plane.
5

Fc? receptors - properties, binding of IgG and the role in induction of various biological functions in cells

100%
Sokal I.
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vol. 49
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issue 1
47-51
6

Cell walls as a source of signals regulating the fate and development of plant cells

88%
Rodakowska E., Kasprowicz A., Lapa A., Luczak A., Derba M., Wojtaszek P.
Biotechnologia
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2006
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issue 4
18-35
EN
Cell walls are the outermost functional zone of plant cells. Although they surround individual cells, at the same time they form a part of supracellular structure ? the apoplast. On the other hand, they are also an indispensable component of the structural and functional continuum formed between cell wall, plasma membrane, and cytoskeleton (WMC continuum), and spanning the whole cell. Thus, cell walls are crucial for the communication of cells with their surrounding. This paper constitutes a short review of the importance of plant cell walls as a source of signalling molecules. Particular attention is paid to: 1) cell walls as a kind of mechanical system characteristic to plants; 2) generation and transport of extracellular signalling molecules, such as signalling peptides and oligosaccharins; 3) apoplastic source of reactive oxygen species and nitric oxide. The review is supplemented with the description of selected results coming from our research group.
7
Content available remote

Molecular basis of dendritic arborization

88%
Urbanska M., Blazejczyk M., Jaworski J.
Acta Neurobiologiae Experimentalis
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2008
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vol. 68
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issue 2
264-288
EN
The pattern of dendritic branching along with the receptor and channel composition and density of synapses regulate the electrical properties of neurons. Abnormalities in dendritic tree development lead to serious dysfunction of neuronal circuits and, consequently, the whole nervous system. Not surprisingly, the complicated and multi-step process of dendritic arbor development is highly regulated and controlled at every stage by both extrinsic signals and intrinsic molecular mechanisms. In this review, we analyze the molecular mechanisms that contribute to cellular processes that are crucial for the proper formation and stability of dendritic arbors, in such distant organisms as insects (e.g. Drosophila melanogaster), amphibians (Xenopus laevis), and mammals.
8

Cellular aspects of regeneration in protoplast culture of yellow lupin (Lupinus luteus L.)

88%
Wiszniewska A., Pindel A.
Biotechnologia
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2010
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issue 2
18-22
EN
Yellow lupin (Lupinus luteus), like many other Fabaceae species, exhibits strong recalcitrance to in vitro conditions of protoplast culture, where regeneration capacity is extremely limited, and only incipient mitoses are observed. In case of the restricted morphogenetic potential of yellow lupin protoplasts, special attention should be paid to the cellular mechanisms that control gaining of totipotency in culture. These are especially: the structure and functioning of new cell wall, elements of cytoskeleton, as well as some cell components of signaling properties. Detailed investigation on these structures and their behaviour in culture conditions may contribute to the understanding and bypassing of the recalcitrance problem in yellow lupin.
9

Intercellular cytoplasm transport during oogenesis of the moth midge, Tinearia alternata Say (Diptera: Psychodidae)

75%
Mazurkiewicz M., Kubrakiewicz J.
Folia Biologica
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2001
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vol. 49
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issue 3-4
205-213
EN
Polytrophic ovaries of the nematocerous dipteran, Tinearia alternata Say consists of several developmentally synchronized ovarioles each housing only one functional egg chamber with 15 nurse cells and an oocyte. At the early stages of previtellogenesis the nurse cells become polyploid and synthetically active. Their nuclei contain polytene chromosomes and prominent nucleoli. With the advance of previtellogenic growth the nurse cell cytoplasm is loaded with the growing number of ribosomes and contain perinuclear nuage material, mitochondria, electron dense bodies and aggregations of endoplasmic reticulum. All these organelles are transported into the oocyte thanks to the massive and rapid flow of the nurse cell cytoplasmic contents. Nurse cell?oocyte transport is mediated by actin cytoskeleton. Prior to the rapid cytoplasm transfer, F-actin network is associated with the nurse cell membranes while tiny bundles of microfilaments form actin baskets connected with ring canals. Nurse cells in Tinearia lack an extensive scaffold of radially oriented, F-actin bundles (cables) that would tether their nuclei in place, thus preventing ring canals from plugging. The way the nuclei are anchored to their central positions within the cells remains unclear. Towards the final stages of oogenesis nurse cells are almost devoid of cytoplasm and degenerate. Although their nuclei undergo dramatic morphological transformations, typical hallmarks of apoptotic pathway could not be clearly observed. Rapid ooplasmic streaming does not occur.
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