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Abdelhak El Amrani - One of the best experts on this subject based on the ideXlab platform.

  • Do Specialized Cells Play a Major Role in Organic Xenobiotic Detoxification in Higher Plants?
    Frontiers in Plant Science, 2020
    Co-Authors: Armand Cave-radet, Mokded Rabhi, Francis Gouttefangeas, Abdelhak El Amrani
    Abstract:

    In the present work, we used a double cell screening approach based on phenanthrene (phe) epifluorescence histochemical localization and oxygen radical detection to generate new data about how some specialized cells are involved in tolerance to organic xenobiotics. Thereby, we bring new insights about phe [a common Polycyclic Aromatic Hydrocarbon (PAH)] cell specific detoxification, in two contrasting plant lineages thriving in different ecosystems. Our data suggest that in higher plants, detoxification may occur in specialized cells such as trichomes and pavement cells inArabidopsis, and in the basal cells of salt glands inSpartinaspecies. Such features were supported by a survey from the literature, and complementary data correlating the size of basal salt gland cells and tolerance abilities to PAHs previously reported betweenSpartinaspecies. Furthermore, we conducted functional validation in two independentArabidopsistrichomeless glabrous T-DNA mutant lines (GLABRA1 mutants). These mutants showed a sensitive phenotype under phe-induced stress in comparison with their background ecotypes without the mutation, indicating that trichomes are key structures involved in the detoxification of organic xenobiotics. Interestingly, trichomes and pavement cells are known to endoreduplicate, and we discussed the putative advantages given by Endopolyploidy in xenobiotic detoxification abilities. The same feature concerning basal salt gland cells inSpartinahas been raised. This similarity with detoxification in the endopolyploid liver cells of the animal system is included.

Pavol Mártonfi - One of the best experts on this subject based on the ideXlab platform.

  • Endopolyploidy pattern in Corydalis early spring geophytes
    Flora, 2020
    Co-Authors: Vladislav Kolarčik, Viera Fráková, Valéria Kocová, Lukáš Koprivý, Pavol Mártonfi
    Abstract:

    Abstract Endopolyploidy, a condition where the nuclear ploidy level of various cells and tissues of an organism increases, is present in diverse plant species. Endopolyploidy contributes to cell enlargement, increases gene expression, and accelerates growth, hence it is associated with cell differentiation, development, and physiology of plants. However, the occurrence of this phenomenon in plants and the diversity of functional roles of Endopolyploidy remains poorly understood. In this study, we have used flow cytometry to perform a detailed survey of the extent and patterns of Endopolyploidy in various organs of two early spring geophytes, Corydalis cava and C. solida. We identified between 2C and 32C ploidy classes. Most of the stem samples contained only endopolyploid cells (4C – 32C) in both species. The endoreduplication index varied between 0.34 (leaf lamina) and 2.45 (basal part of the stem). Both species showed a similar level of Endopolyploidy, and the Endopolyploidy index exceeded 1.5 in the root, tuber, stem, peduncle, petiole, and scale leaf of at least one species. The Endopolyploidy index differed in leaf lamina, ovary, style, and stamen between two species. Compared to other angiosperm groups, Corydalis may be included into highly endopolyploid plants. Geophytism is generally associated with high genome size, but this is not the case in Corydalis. We hypothesised that high Endopolyploidy level found in Corydalis may compensate for the low genome size and thus help to promote plant growth during the early spring.

  • Salinity Has no Effect on Polysomatic Pattern in Seedlings of Trifolium pratense and T. repens
    Acta Biologica Cracoviensia s. Botanica, 2017
    Co-Authors: Valéria Kocová, Vladislav Kolarčik, Dominika Bubanová, Albert Rákai, Pavol Mártonfi
    Abstract:

    AbstractEndopolyploidy is a condition of a cell containing reduplicated genetic material in its nucleus. Cells with the nuclei of different ploidy levels are often present within a single polysomatic organism. Endoreduplication is thus a modified cell cycle that omits cytokinesis and leads to chromatin replication in the endopolyploid cells. This study aimed to research the effect of salinity on Endopolyploidy ofTrifolium pratenseandT. repens. Both species are important pasture legumes and belong to the genusFabaceaewith the well documented Endopolyploidy occurence. Endopolyploidy levels in the seedlings treated with 0, 30, 60, 90 and 120 mM NaCl were investigated by flow cytometry. The seedling organs were evaluated during three ontogeny stages. The cytometric data plotted on a histogram showed the presence of 2C-16C nuclei inT. pratenseand 2C-8C inT. repens. The hypothesis that salinity induces additional endocycles was not confirmed. Our results show that the distribution of nuclei among ploidy levels does not differ markedly between the treatment groups and the control ones. Additionally, only minor changes were observed among the endoreduplication indexes (EI) of plant organs after exposure to various salt concentrations. Endopolyploidy patterns within the salt-treated seedlings during ontogeny are similar to the controls. We suggest that Endopolyploidy inTrifoliumspecies is a conserved genetic trait, rather than an adaptation to salinity stress. The analyses of the roots ofT. pratenseat stage III show that with the increased concentrations of NaCl the length of roots decreased, but no evident changes in Endopolyploidy occured.

  • Endoreduplication as a part of flower ontogeny in Trifolium pratense cultivars
    Botanical studies, 2016
    Co-Authors: Valéria Kocová, Vladislav Kolarčik, Albert Rákai, Nikola Straková, Pavol Mártonfi
    Abstract:

    Endoreduplication appears in numerous plant species and plays a vital role during ontogeny. The presence of polyploid cells in an otherwise diploid organism is tied specifically to the taxonomy, ecology and physiology of the studied specimen. Little is known about the changes in Endopolyploidy levels of floral organs during their development. In order to uncover the workings of endoreduplication in polysomatic species, our study examines flowers of T. pratense in three ontogenetic stages by means of flow cytometry. Cultivar ‘Manuela’ is characterized by the presence of 2C–8C and ‘Dajana’ 2C–16C nuclei. In general, the frequencies of nuclei only slightly changed during development. Endopolyploidy levels represented by endoreduplication index (EI) in the ‘Manuela’ sepals and stamens showed statistical differences between young and old stages, other organs of both cultivars between stages are not statistically different. Significant differences between ‘Manuela’ and ‘Dajana’ cultivars were found only in sepals of I. stage, and in petals and carpels of III. stage. Cultivars showed a similar pattern of Endopolyploidy. However, a considerable decrease in EI ‘Manuela’ petals and carpels at III. stage was detected as opposed to ‘Dajana’. Overall, a higher endoreduplication index is distinctive for organs of the ‘Dajana’ cultivar. In this study we prove the permanent presence of endopolyploid cells in the floral organs of T. pratense throughout their development.

  • Endopolyploidy PATTERNS IN ORGANS OF TRIFOLIUM SPECIES (FABACEAE)
    Acta Biologica Cracoviensia s. Botanica, 2014
    Co-Authors: Valéria Kocová, Vladislav Kolarčik, Nikola Straková, Pavol Mártonfi
    Abstract:

    The pattern of Endopolyploidy in the genus Trifolium was studied in mature organs of T. montanum and T. repens at reproductive stage, with comparative data for T. pratense, all from natural populations. Endopolyploidy in root, stem, petiole, leaf, inflorescence stalk, sepal, petal, stamen and carpel was detected by flow cytometry. 2C, 4C and 8C nuclei were found in organs of T. montanum and T. repens, and additionally 16C nuclei in organs of T. repens. The organs of T. montanum and T. repens differed in degree of Endopolyploidy based on cycle values calculated from flow cytometry data; it was lowest in leaf and sepal in T. montanum and T. repens, and highest in T. montanum in petal and carpel and in T. repens in petiole and inflorescence stalk. These results are also seen in the two or more peaks of interphase nuclei in the flow cytometry histograms. There were significant correlations between the organs of T. pratense and T. repens as well as substantial differences between Trifolium species in the degree of Endopolyploidy. T. pratense showed higher absolute Endopolyploidy than T. montanum and T. repens. Principal component analysis showed that individuals of T. repens and T. montanum are more similar to each other than to individuals of T. pratense in degree of Endopolyploidy. The observed variation between species might be explained by phylogenetic relationships and genome size differences.

  • Endopolyploidy in organs of Trifolium pratense L.in different ontogenetic stages
    Caryologia, 2014
    Co-Authors: Nikola Straková, Vladislav Kolarčik, Valéria Kocová, Pavol Mártonfi
    Abstract:

    Endopolyploidy is a common feature in seed plants. This phenomenon occurs during early development. Flow cytometry of 54 individuals of the species Trifolium pratense variety Manuela, in the vegetative organs during four ontogenetic stages is described. Fresh plant material grown from seeds was used for the analysis. The calculation made on the basis of the mean cycle value revealed that the level of Endopolyploidy is different in various organs during the ontogeny. The highest Endopolyploidy was recorded in the cotyledons of the first stage (1.0) and the lowest in the third leaf of the fourth ontogenetic stage (0.18). It was noticed that the degree of Endopolyploidy decreased during the ontogeny in most of the plants and thus the ontogenetically oldest organs had higher Endopolyploidy than the younger ones.

Jean-pierre Renaudin - One of the best experts on this subject based on the ideXlab platform.

  • Endoreduplication and fruit growth in tomato:evidences in favour of the karyoplasmic ratio theory
    2013
    Co-Authors: Christian Chevalier, Julien Pirrello, Catherine Cheniclet, Mickael Bourge, Jean-pierre Renaudin, Spencer C Brown, Mathieu Bourdon, Nathalie Frangne
    Abstract:

    Endopolyploidy occurs in many plant species and supports the process of differentiation of cells and organs. The functional role of Endopolyploidy in plant cells remains poorly understood, mainly because the analysis is hampered by the fact that complex polyploid tissues usually include cells with different ploidy levels. During the development of tomato fruit, cells from the (fleshy) pericarp tissue become highly polyploid reaching DNA content barely encountered in other plant species (between 2C and 512C). To investigate the spatial and temporal distribution of Endopolyploidy, it is necessary to address the DNA content of individual nuclei in situ. Populations of nuclei with different ploidy levels were isolated to characterize at the cytological level the consequences of Endopolyploidy on the ultrastructure of nuclear and nucleolar chromatin, the nuclear shape and the relationship with other cellular organelles such as mitochondria. We were able to develop a new method based on BAC-FISH to determine in situ the ploidy level of different nuclei and consequently establish a ploidy map of tomato fruit pericarp. Based on this map, we demonstrated a link between the ploidy level, the complexity of nuclear shape and the number of mitochondria in the vicinity of polyploid nuclei. We were able to provide the first direct evidence that endoreduplication plays a role in the increased transcription of rRNA and mRNA in plant cells. We thus provided quantitative data in favour of the ‘karyoplasmic ratio’ theory and showed that endoreduplication is associated with a complex cellular re-organization during development of tomato fruit.

  • Evidence for karyoplasmic homeostasis during endoreduplication and a ploidy-dependent increase in gene transcription during tomato fruit growth
    Development (Cambridge England), 2012
    Co-Authors: Matthieu Bourdon, Julien Pirrello, Catherine Cheniclet, Olivier Coriton, Mickael Bourge, Spencer Brown, Adeline Moïse, Martine Peypelut, Valérie Rouyère, Jean-pierre Renaudin
    Abstract:

    Endopolyploidy is a widespread process that corresponds to the amplification of the genome in the absence of mitosis. In tomato, very high ploidy levels (up to 256C) are reached during fruit development, concomitant with very large cell sizes. Using cellular approaches (fluorescence and electron microscopy) we provide a structural analysis of endoreduplicated nuclei at the level of chromatin and nucleolar organisation, nuclear shape and relationship with other cellular organelles such as mitochondria. We demonstrate that Endopolyploidy in pericarp leads to the formation of polytene chromosomes and markedly affects nuclear structure. Nuclei manifest a complex shape, with numerous deep grooves that are filled with mitochondria, affording a fairly constant ratio between nuclear surface and nuclear volume. We provide the first direct evidence that Endopolyploidy plays a role in increased transcription of rRNA and mRNA on a per-nucleus basis. Overall, our results provide quantitative evidence in favour of the karyoplasmic theory and show that endoreduplication is associated with complex cellular organisation during tomato fruit development.

  • In planta quantification of endoreduplication using fluorescent in situ hybridization (FISH).
    Plant Journal, 2011
    Co-Authors: Matthieu Bourdon, Julien Pirrello, Catherine Cheniclet, Olivier Coriton, Jean-pierre Renaudin, Spencer C Brown, Christel Poujol, Christian Chevalier, Nathalie Frangne
    Abstract:

    Endopolyploidy, i.e. amplification of the genome in the absence of mitosis, occurs in many plant species and happens along with organ and cell differentiation. Deciphering the functional roles of Endopolyploidy is hampered by the fact that polyploid tissues generally comprise cells with various ploidy levels. In some fleshy fruits (amongst them tomato fruit) the ploidy levels present at the end of development range from 2C to 256C in the same tissue. To investigate the temporal and spatial distribution of Endopolyploidy it is necessary to address the DNA content of individual nuclei in situ. Conventional methods such as fluorometry or densitometry can be used for some tissues displaying favorable characteristics, e.g. small cells, small nuclei, organization in a monolayer, but high levels of varying polyploidy are usually associated with large sizes of nuclei and cells, in a complex three dimensional (3-D) organization of the tissues. The conventional methods are inadequate for such tissue, becoming semi-quantitative and imprecise. We report here the development of a new method based on fluorescent in situ bacterial artificial chromosome hybridizations that allows the in situ determination of the DNA ploidy level of individual nuclei. This method relies on the counting of hybridization signals and not on intensity measurements and is expected to provide an alternative method for mapping Endopolyploidy patterns in mature, 3-D organized plant tissues as illustrated by the analysis of ploidy level and cell size in pericarp from mature green tomato fruit.

John H. Doonan - One of the best experts on this subject based on the ideXlab platform.

  • Endopolyploidy as a potential alternative adaptive strategy for Arabidopsis leaf size variation in response to UV-B
    Journal of experimental botany, 2014
    Co-Authors: Vasilis C. Gegas, Jason J. Wargent, Edouard Pesquet, Emma Granqvist, Nigel D. Paul, John H. Doonan
    Abstract:

    The extent of endoreduplication in leaf growth is group- or even species-specific, and its adaptive role is still unclear. A survey of Arabidopsis accessions for variation at the level of Endopolyploidy, cell number, and cell size in leaves revealed extensive genetic variation in Endopolyploidy level. High Endopolyploidy is associated with increased leaf size, both in natural and in genetically unstructured (mapping) populations. The underlying genes were identified as quantitative trait loci that control Endopolyploidy in nature by modulating the progression of successive endocycles during organ development. This complex genetic architecture indicates an adaptive mechanism that allows differential organ growth over a broad geographic range and under stressful environmental conditions. UV-B radiation was identified as a significant positive climatic predictor for high Endopolyploidy. Arabidopsis accessions carrying the increasing alleles for Endopolyploidy also have enhanced tolerance to UV-B radiation. UV-absorbing secondary metabolites provide an additional protective strategy in accessions that display low Endopolyploidy. Taken together, these results demonstrate that high constitutive Endopolyploidy is a significant predictor for organ size in natural populations and is likely to contribute to sustaining plant growth under high incident UV radiation. Endopolyploidy may therefore form part of the range of UV-B tolerance mechanisms that exist in natural populations.

Jekaterina Erenpreisa - One of the best experts on this subject based on the ideXlab platform.

  • Endopolyploidy in irradiated p53 deficient tumour cell lines persistence of cell division activity in giant cells expressing aurora b kinase
    Cell Biology International, 2008
    Co-Authors: Jekaterina Erenpreisa, Alim P. Anisimov, Andrei Ivanov, Sally P Wheatley, Elizabeth A Kosmacek, Fiorenza Ianzini, Michael A Mackey, Paul J Davis, Grigorijs Plakhins, Timothy M Illidge
    Abstract:

    Recent findings including computerised live imaging suggest that polyploidy cells transiently emerging after severe genotoxic stress (and named 'endopolyploid cells') may have a role in tumour regrowth after anti-cancer treatment. Until now, mostly the factors enabling metaphase were studied in them. Here we investigate the mitotic activities and the role of Aurora-B, in view of potential depolyploidisation of these cells, because Aurora-B kinase is responsible for coordination and completion of mitosis. We observed that endopolyploid giant cells are formed via different means in irradiated p53 tumours, by: (1) division/fusion of daughter cells creating early multi-nucleated cells; (2) asynchronous division/fusion of sub-nuclei of these multi-nucleated cells; (3) a series of polyploidising mitoses reverting replicative interphase from aborted metaphase and forming giant cells with a single nucleus; (4) micronucleation of arrested metaphases enclosing genome fragments; or (5) incomplete division in the multi-polar mitoses forming late multi-nucleated giant cells. We also observed that these activities can release para-diploid cells, although infrequently. While apoptosis typically occurs after a substantial delay in these cells, we also found that approximately 2% of the endopolyploid cells evade apoptosis and senescence arrest and continue some form of mitotic activity. We describe here that catalytically active Aurora-B kinase is expressed in the nuclei of many endopolyploid cells in interphase, as well as being present at the centromeres, mitotic spindle and cleavage furrow during their attempted mitotes. The totally micronucleated giant cells (containing sub-genomic fragments in multiple micronuclei) represented only the minor fraction which failed to undergo mitosis, and Aurora-B was absent from it. These observations suggest that most endopolyploid tumour cells are not reproductively inert and that Aurora-B may contribute to the establishment of resistant tumours post-irradiation.

  • mitotic catastrophe and endomitosis in tumour cells an evolutionary key to a molecular solution
    Cell Biology International, 2005
    Co-Authors: Jekaterina Erenpreisa, Martins Kalejs, Mark S Cragg
    Abstract:

    Following genotoxic insult, p53 mutated tumour cells undergo mitotic catastrophe. This is characterised by a switch from mitosis to the endocycle. The essential difference between mitosis and the endocycle is that in the latter, DNA synthesis is uncoupled from cell division, which leads to the formation of endopolyploid cells. Recent data suggests that a return from the endocycle into mitosis is also possible. Furthermore, our observations indicate that a particular type of endocycle known as endomitosis may be involved in this return. Here we review the role of endomitosis in the somatic reduction of polyploidy during development and its postulated role in the evolution of meiosis. Finally, we incorporate these evolutionary data to help interpret our most recent observations in the tumour cell system, which indicate a role for endomitosis and meiotic regulators, in particular p39mos in the segregation of genomes (somatic reduction) of these endopolyploid cells.