The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Gregorio Hueros - One of the best experts on this subject based on the ideXlab platform.
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Establishment of Cereal Endosperm Expression Domains Identification and Properties of a Maize Transfer Cell–Specific Transcription Factor, ZmMRP-1
The Plant cell, 2002Co-Authors: Elisa Gómez, Joaquín Royo, Yan Guo, Richard D. Thompson, Gregorio HuerosAbstract:In maize, cells at the base of the endosperm are transformed into transfer cells that facilitate nutrient uptake by the developing seed. ZmMRP-1 is the first transfer cell-specific transcriptional activator to be identified. The protein it encodes contains nuclear localization signals and a MYB-related DNA binding domain. A single gene copy is present in maize, mapping to a locus on chromosome 8. ZmMRP-1 is first expressed soon after fertilization, when the endosperm is still a multinuclear Coenocyte. The transcript accumulates in the basal nucleocytoplasmic domain that gives rise to transfer cells after cellularization. The transcript can be detected throughout transfer cell development, but it is not found in mature cells. ZmMRP-1 strongly transactivates the promoters of two unrelated transfer cell-specific genes. The properties of ZmMRP-1 are consistent with it being a determinant of transfer cell-specific expression. Possible roles for ZmMRP-1 in the regulation of endosperm and transfer cell differentiation are discussed.
Iñaki Ruiz-trillo - One of the best experts on this subject based on the ideXlab platform.
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A unicellular relative of animals generates a layer of polarized cells by actomyosin-dependent cellularization.
eLife, 2019Co-Authors: Omaya Dudin, Arthur Ab Haraldsen, Andrej Ondracka, Xavier Grau-bové, Atsushi Toyoda, Hiroshi Suga, Jon Bråte, Iñaki Ruiz-trilloAbstract:In animals, cellularization of a Coenocyte is a specialized form of cytokinesis that results in the formation of a polarized epithelium during early embryonic development. It is characterized by coordinated assembly of an actomyosin network, which drives inward membrane invaginations. However, whether coordinated cellularization driven by membrane invagination exists outside animals is not known. To that end, we investigate cellularization in the ichthyosporean Sphaeroforma arctica, a close unicellular relative of animals. We show that the process of cellularization involves coordinated inward plasma membrane invaginations dependent on an actomyosin network and reveal the temporal order of its assembly. This leads to the formation of a polarized layer of cells resembling an epithelium. We show that this stage is associated with tightly regulated transcriptional activation of genes involved in cell adhesion. Hereby we demonstrate the presence of a self-organized, clonally-generated, polarized layer of cells in a unicellular relative of animals.
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A unicellular relative of animals generates an epithelium-like cell layer by actomyosin-dependent cellularization
2019Co-Authors: Omaya Dudin, Arthur Ab Haraldsen, Andrej Ondracka, Xavier Grau-bové, Atsushi Toyoda, Hiroshi Suga, Jon Bråte, Iñaki Ruiz-trilloAbstract:SummaryIn animals, cellularization of a Coenocyte is a specialized form of cytokinesis that results in the formation of a polarized epithelium during early embryonic development. It is characterized by coordinated assembly of an actomyosin network, which drives inward membrane invaginations. However, whether coordinated cellularization driven by membrane invagination exists outside animals is not known. To that end, we investigate cellularization in the ichthyosporean Sphaeroforma arctica, a close unicellular relative of animals. We show that the process of cellularization involves coordinated inward plasma membrane invaginations dependent on an actomyosin network, and reveal the temporal order of its assembly. This leads to the formation of a polarized layer of cells resembling an epithelium. We show that this epithelium-like stage is associated with tightly regulated transcriptional activation of genes involved in cell adhesion. Hereby we demonstrate the presence of a selforganized, clonally-generated, polarized layer of cells in a unicellular relative of animals.
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Decoupling of Nuclear Division Cycles and Cell Size during the Coenocytic Growth of the Ichthyosporean Sphaeroforma arctica
Current biology : CB, 2018Co-Authors: Andrej Ondracka, Omaya Dudin, Iñaki Ruiz-trilloAbstract:Summary Coordination of the cell division cycle with the growth of the cell is critical to achieve cell size homeostasis [1]. Mechanisms coupling the cell division cycle with cell growth have been described across diverse eukaryotic taxa [2–4], but little is known about how these processes are coordinated in organisms that undergo more complex life cycles, such as coenocytic growth. Coenocytes (multinucleate cells formed by sequential nuclear divisions without cytokinesis) are commonly found across the eukaryotic kingdom, including in animal and plant tissues and several lineages of unicellular eukaryotes [5]. Among the organisms that form Coenocytes are ichthyosporeans, a lineage of unicellular holozoans that are of significant interest due to their phylogenetic placement as one of the closest relatives of animals [6]. Here, we characterize the coenocytic cell division cycle in the ichthyosporean Sphaeroforma arctica . We observe that, in laboratory conditions, S. arctica cells undergo a uniform and easily synchronizable coenocytic cell cycle, reaching up to 128 nuclei per cell before cellularization and release of daughter cells. Cycles of nuclear division occur synchronously within the Coenocyte and in regular time intervals (11–12 hr). We find that the growth of cell volume is dependent on concentration of nutrients in the media; in contrast, the rate of nuclear division cycles is constant over a range of nutrient concentrations. Together, the results suggest that nuclear division cycles in the coenocytic growth of S. arctica are driven by a timer, which ensures periodic and synchronous nuclear cycles independent of the cell size and growth.
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Decoupling of the nuclear division cycle and cell size control in the coenocytic cycle of the ichthyosporean Sphaeroforma arctica
2017Co-Authors: Andrej Ondracka, Iñaki Ruiz-trilloAbstract:Coenocytes (multinucleated cells formed by sequential nuclear divisions without cytokinesis) are commonly found across the eukaryotic kingdom, including in animals, plants and several lineages of unicellular eukaryotes. Despite their commonality, little is known about how cell growth, nuclear divisions and cell divisions are coordinated in Coenocytes. Among the unicellular eukaryotes that form Coenocytes are ichthyosporeans, a lineage of unicellular holozoans that are of significant interest due to their phylogenetic placement as one of the closest relatives to animals. Here, we characterize the coenocytic cell division cycle in the ichthyosporean Sphaeroforma arctica. In laboratory conditions, we observed that S. arctica cells undergo a highly regular periodic coenocytic cell cycle. Nuclear division cycles occur synchronously within the Coenocyte and in regular time intervals (~11 hours per nuclear cycle) until reaching 64-128 nuclei and releasing daughter cells. The duration of the nuclear division cycles is constant across a wide range of nutrient concentration. In contrast, the volume of the Coenocytes increase more slowly in lower nutrient concentration, which also results in smaller newborn daughter cells. This suggests that S. arctica cells are capable to adapt the cell growth rate to nutrient concentration while maintaining the timing of nuclear division cycles, suggesting that in ichthyosporeans the mechanisms regulating highly periodic nuclear division cycles operate independently from mechanisms sensing the cell size.
Daniel H. Chitwood - One of the best experts on this subject based on the ideXlab platform.
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Plant architecture without multicellularity: quandaries over patterning and the soma-germline divide in siphonous algae
Frontiers in plant science, 2015Co-Authors: Viktoriya Coneva, Daniel H. ChitwoodAbstract:Multicellularity has independently evolved numerous times throughout the major lineages of life. Often, multicellularity can enable complex, macroscopic organismal architectures but it is not required for the elaboration of morphology. Several alternative cellular strategies have arisen as solutions permitting exquisite forms. The green algae class Ulvophyceae, for example, contains truly multicellular organisms, as well as macroscopic siphonous cells harboring one or multiple nuclei, and siphonocladous species, which are multinucleate and multicellular. These diverse cellular organizations raise a number of questions about the evolutionary and molecular mechanisms underlying complex organismal morphology in the green plants. Importantly, how does morphological patterning arise in giant Coenocytes, and do nuclei, analogous to cells in multicellular organisms, take on distinct somatic and germline identities? Here, we comparatively explore examples of patterning and differentiation in diverse coenocytic and single-cell organisms and discuss possible mechanisms of development and nuclear differentiation in the siphonous algae.
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An intracellular transcriptomic atlas of the giant Coenocyte Caulerpa taxifolia.
PLoS genetics, 2015Co-Authors: Aashish Ranjan, Brad Townsley, Yasunori Ichihashi, Neelima Sinha, Daniel H. ChitwoodAbstract:Convergent morphologies have arisen in plants multiple times. In non-vascular and vascular land plants, convergent morphology in the form of roots, stems, and leaves arose. The morphology of some green algae includes an anchoring holdfast, stipe, and leaf-like fronds. Such morphology occurs in the absence of multicellularity in the siphonous algae, which are single cells. Morphogenesis is separate from cellular division in the land plants, which although are multicellular, have been argued to exhibit properties similar to single celled organisms. Within the single, macroscopic cell of a siphonous alga, how are transcripts partitioned, and what can this tell us about the development of similar convergent structures in land plants? Here, we present a de novo assembled, intracellular transcriptomic atlas for the giant Coenocyte Caulerpa taxifolia. Transcripts show a global, basal-apical pattern of distribution from the holdfast to the frond apex in which transcript identities roughly follow the flow of genetic information in the cell, transcription-to-translation. The analysis of the intersection of transcriptomic atlases of a land plant and Caulerpa suggests the recurrent recruitment of transcript accumulation patterns to organs over large evolutionary distances. Our results not only provide an intracellular atlas of transcript localization, but also demonstrate the contribution of transcript partitioning to morphology, independent from multicellularity, in plants.
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An Intracellular Transcriptomic Atlas of the Giant
2015Co-Authors: Coenocyte Caulerpa Taxifolia, Aashish Ranjan, Brad Townsley, Yasunori Ichihashi, Neelima R. Sinha, Daniel H. ChitwoodAbstract:Convergent morphologies have arisen in plants multiple times. In non-vascular and vascular land plants, convergent morphology in the form of roots, stems, and leaves arose. The morphology of some green algae includes an anchoring holdfast, stipe, and leaf-like fronds. Such morphology occurs in the absence of multicellularity in the siphonous algae, which are single cells. Morphogenesis is separate from cellular division in the land plants, which although are multicellular, have been argued to exhibit properties similar to single celled organisms. Within the single, macroscopic cell of a siphonous alga, how are transcripts partitioned, and what can this tell us about the development of similar convergent structures in land plants? Here, we present a de novo assembled, intracellular transcriptomic atlas for the giant Coenocyte Caulerpa taxifolia. Transcripts show a global, basal-apical pattern of distribution from the holdfast to the frond apex in which transcript identities roughly follow the flow of genetic information in the cell, transcription-to-translation. The analysis of the intersection of transcriptomic atlases of a land plant and Caulerpa suggests the recurrent recruitment of transcript accumulation patterns to organs over large evolutionary distances. Our results not only provide an intracellular atlas of transcript localization, but also demonstrate the contribution of transcript partitioning to morphology, independent from multicellularity, in plants
Elisa Gómez - One of the best experts on this subject based on the ideXlab platform.
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Establishment of Cereal Endosperm Expression Domains Identification and Properties of a Maize Transfer Cell–Specific Transcription Factor, ZmMRP-1
The Plant cell, 2002Co-Authors: Elisa Gómez, Joaquín Royo, Yan Guo, Richard D. Thompson, Gregorio HuerosAbstract:In maize, cells at the base of the endosperm are transformed into transfer cells that facilitate nutrient uptake by the developing seed. ZmMRP-1 is the first transfer cell-specific transcriptional activator to be identified. The protein it encodes contains nuclear localization signals and a MYB-related DNA binding domain. A single gene copy is present in maize, mapping to a locus on chromosome 8. ZmMRP-1 is first expressed soon after fertilization, when the endosperm is still a multinuclear Coenocyte. The transcript accumulates in the basal nucleocytoplasmic domain that gives rise to transfer cells after cellularization. The transcript can be detected throughout transfer cell development, but it is not found in mature cells. ZmMRP-1 strongly transactivates the promoters of two unrelated transfer cell-specific genes. The properties of ZmMRP-1 are consistent with it being a determinant of transfer cell-specific expression. Possible roles for ZmMRP-1 in the regulation of endosperm and transfer cell differentiation are discussed.
Odd-arne Olsen - One of the best experts on this subject based on the ideXlab platform.
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and Cell Fate Specification
2001Co-Authors: Odd-arne OlsenAbstract:■ Abstract The endosperm develops from the central cell of the megagametophyte after introduction of the second male gamete into the diploid central cell. Of the three forms of endosperm in angiosperms, the nuclear type is prevalent in economically important species, including the cereals. Landmarks in nuclear endosperm development are the coenocytic, cellularization, differentiation, and maturation stages. The differentiated endosperm contains four major cell types: starchy endosperm, aleurone, transfer cells, and the cells of the embryo surrounding region. Recent research has demonstrated that the first two phases of endosperm occur via mechanisms that are conserved among all groups of angiosperms, involving directed nuclear migration during the coenocytic stage and anticlinal cell wall deposition by cytoplasmic phragmoplasts formed in interzones between radial microtubular systems emanating from nuclear membranes. Complete cellularization of the endosperm Coenocyte is achieved through centripetal growth of cell files, extending to the center of the endosperm cavity. Key points in cell cycle control and control of the MT (microtubular) cytoskeletal apparatus central to endosperm development are discussed. Specification of cell fates in the cereal endosperm appears to occur via positional signaling; cells in peripheral positions, except over the main vascular tissues, assume aleurone cell fate. Cells over the main vascular tissue become transfer cells and all interior cells become starchy endosperm cells. Studies in maize have implicated Crinkly4, a protein receptor kinase-like molecule, in aleurone cell fate specification.
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ENDOSPERM DEVELOPMENT: Cellularization and Cell Fate Specification
Annual review of plant physiology and plant molecular biology, 2001Co-Authors: Odd-arne OlsenAbstract:▪ Abstract The endosperm develops from the central cell of the megagametophyte after introduction of the second male gamete into the diploid central cell. Of the three forms of endosperm in angiosperms, the nuclear type is prevalent in economically important species, including the cereals. Landmarks in nuclear endosperm development are the coenocytic, cellularization, differentiation, and maturation stages. The differentiated endosperm contains four major cell types: starchy endosperm, aleurone, transfer cells, and the cells of the embryo surrounding region. Recent research has demonstrated that the first two phases of endosperm occur via mechanisms that are conserved among all groups of angiosperms, involving directed nuclear migration during the coenocytic stage and anticlinal cell wall deposition by cytoplasmic phragmoplasts formed in interzones between radial microtubular systems emanating from nuclear membranes. Complete cellularization of the endosperm Coenocyte is achieved through centripetal growt...
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Isolation of molecular markers from the barley endosperm Coenocyte and the surrounding nucellus cell layers
Plant Molecular Biology, 1996Co-Authors: Danny N. P. Doan, Casper Linnestad, Odd-arne OlsenAbstract:The cereal endosperm develops from a Coenocyte to a cellular storage organ through formation of nucleo-cytoplasmic domains and cell wall deposition in the interzones between these domains. During its early stages, the endosperm develops in close contact with nucellus, the sporophytic tissue which gives rise to the megagametophyte. Owing to the positioning of the two tissues deeply within the ovary, neither cell types have been easily accessible for molecular studies. In this paper we report for the first time the cloning of molecular markers for the barley endosperm Coenocyte and the nucellus. The novel END1 and NUC1 cDNAs were isolated by differential screening of a cDNA library from 5 DAP (days after pollination) ovaries using a positive probe from hand-dissected embryo sacs with adhering nucellus and testa cell layers, and a negative probe from pericarp. In situ and northern blot hybridization data show that END1 transcripts are asymmetrically distributed in teh endosperm Coenocyte limited to an area over the nucellar projection. In the cellular endosperm, END1 transcripts are present in modified aleurone cells and a few layers of ventral starchy endosperm cells. The second clone, NUC1, hybridizes to transcripts in the nucellus before fertilization and in autolyzing nucellus cells after fertilization. At later stages, after the disappearance of nucellus, NUC1 transcripts are present in the nucellar epidermis and in the lateral cells of the nucellar projection. This work provide tools for future elucidation of the genes specifying endosperm histogenesis.