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Teruo Shimmen - One of the best experts on this subject based on the ideXlab platform.
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involvement of actin filaments in Rhizoid morphogenesis of spirogyra
Physiologia Plantarum, 2009Co-Authors: Katsuhisa Yoshida, Teruo ShimmenAbstract:: The role of actin filaments in Rhizoid morphogenesis was studied in Spirogyra. When the algal filaments were severed, new terminal cells started tip growth and finally formed Rhizoids. Actin inhibitors, latrunculin B and cytochalasin D, reversibly inhibited the process. A mesh-like structure of actin filaments (AFs) was formed at the tip region. Gd(3+) inhibited tip growth and decreased AFs in the tip region. Either a decrease in turgor pressure or lowering of the external Ca(2+) concentration also induced similar results. It was suggested that the mesh-like AF structure is indispensable for the elongation of Rhizoids. A possible organization mechanism of the mesh-like AF structure was discussed.
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Rhizoid differentiation of spirogyra is regulated by substratum
Journal of Plant Research, 2008Co-Authors: Hisato Ikegaya, Seiji Sonobe, Kohei Murakami, Teruo ShimmenAbstract:Some species of Spirogyra can anchor to substratum with rod- or rosette-shaped Rhizoid (hapteron). The Rhizoid differentiation can be induced by cutting algal filaments in a laboratory. Requirement of contact stimulation for Rhizoid differentiation has been reported (Nagata in Plant Cell Physiol 14:531–541, 1973a). However, the control mechanism of Rhizoid morphology has not been elucidated. When cut filaments were incubated on the glass surface, start of tip growth, secretion of lectin-binding material and callose synthesis were observed. In the absence of contact to the glass surface, none of above phenomena was induced. Systematic analysis showed that rosette-shaped Rhizoid was formed only on the hydrophobic substratum. On the hydrophobic substratum, both Bandeiraea (Griffonia) simplicifolia lectin and jacalin strongly stained the Rhizoids. On the hydrophilic substratum, however, only Bandeiraea (Griffonia) simplicifolia lectin strongly stained the Rhizoids.
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saponin induced release of single cells from filaments and Rhizoid differentiation in spirogyra
Journal of Plant Research, 2004Co-Authors: Hisato Ikegaya, Seiji Sonobe, Shinya Yamada, Teruo ShimmenAbstract:Some species of Spirogyra living in streams can anchor to the substratum by differentiating a Rhizoid from a terminal cell of a filament. Rhizoid differentiation occurs in the light but not in the dark. When a filament of Spirogyra sp. competent for Rhizoid differentiation was incubated in a medium containing 0.1% saponin, terminal cells were released one by one, forming single cells. Single cells effectively differentiated to be Rhizoids when saponin in the incubation medium was removed. The single-cell system developed in the present study seems suitable for analysis of gene expression during Rhizoid differentiation of Spirogyra.
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synthesis of a callosic substance during Rhizoid differentiation in spirogyra
Plant and Cell Physiology, 2003Co-Authors: Shinya Yamada, Seiji Sonobe, Teruo ShimmenAbstract:;Spirogyra living in running water is anchored to the substratum by Rhizoids that form at the ends of the filaments. A new terminal cell differentiates into a Rhizoid cell if the filament is injured. The mode of growth changes from diffuse to tip growth when Rhizoid differentiation begins. In this study, we found that a callosic substance was synthesized during Rhizoid differentiation. Decreasing the cell turgor, lowering extracellular Ca 2+ or adding Gd 3+ , all inhibited the commencement of Rhizoid differentiation as well as synthesis of the callose-like substance at the tip of the terminal cell. A callosic substance was also synthesized during formation of the conjugation tube.
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involvement of microtubules in Rhizoid differentiation of spirogyra species
Protoplasma, 2003Co-Authors: K Yoshida, Naoko Inoue, Seiji Sonobe, Teruo ShimmenAbstract:Some species of Spirogyra form rosette-shaped or rod-shaped Rhizoids in the terminal cell of the filaments. In the present study, we analyzed an involvement of microtubules (MTs) in Rhizoid differentiation. Before Rhizoid differentiation, cortical MTs were arranged transversely to the long axis of cylindrical cells, reflecting the diffuse growth. At the beginning of Rhizoid differentiation, MTs were absent from the extreme tip of the terminal cell. In the other area of the cell, however, MTs were arranged transversely to the long axis of the cell. In the fully differentiated rosette-shaped Rhizoid, MTs were randomly organized. However, at a younger stage of rosette-shaped Rhizoids, MTs were sometimes arranged almost transversely in the lobes of the rosette. In the rod-shaped Rhizoid, MTs were arranged almost transversely. MT-destabilizing drugs (oryzalin and propyzamide) induced swelling of Rhizoids, and neither rosette-shaped nor rod-shaped Rhizoids were formed. The role of MTs in Rhizoid differentiation was discussed.
Channarong Rodkhum - One of the best experts on this subject based on the ideXlab platform.
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virulence assay of Rhizoid and non Rhizoid morphotypes of flavobacterium columnare in red tilapia oreochromis sp fry
Journal of Fish Diseases, 2016Co-Authors: Ha Thanh Dong, Saengchan Senapin, Benjamin R Lafrentz, Channarong RodkhumAbstract:: Numerous isolates of Flavobacterium columnare were previously recovered from red tilapia, Oreochromis sp., exhibiting columnaris-like disease in Thai farms, and the phenotypic and genetic characteristics were described. The objective of this study was to determine the virulence of two morphotypes (Rhizoid and non-Rhizoid colonies) of F. columnare and to determine their ability to adhere to and persist in red tilapia fry. The results showed that the typical Rhizoid isolate (CUVET1214) was a highly virulent isolate and caused 100% mortality within 24 h following bath challenge of red tilapia with three different doses. The non-Rhizoid isolate (CUVET1201) was avirulent to red tilapia fry. Both morphotypes adhered to and persisted in tilapia similarly at 0.5 and 6 h post-challenge as determined by whole fish bacterial loads. At 24 and 48 h post-challenge, fry challenged with the Rhizoid morphotype exhibited significantly higher bacterial loads than the non-Rhizoid morphotype. The results suggested that an inability of the non-Rhizoid morphotype to persist in tilapia fry may explain lack of virulence.
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Virulence assay of Rhizoid and non‐Rhizoid morphotypes of Flavobacterium columnare in red tilapia, Oreochromis sp., fry
Journal of Fish Diseases, 2015Co-Authors: Ha Thanh Dong, Saengchan Senapin, Benjamin R Lafrentz, Channarong RodkhumAbstract:Numerous isolates of Flavobacterium columnare were previously recovered from red tilapia, Oreochromis sp., exhibiting columnaris-like disease in Thai farms, and the phenotypic and genetic characteristics were described. The objective of this study was to determine the virulence of two morphotypes (Rhizoid and non-Rhizoid colonies) of F. columnare and to determine their ability to adhere to and persist in red tilapia fry. The results showed that the typical Rhizoid isolate (CUVET1214) was a highly virulent isolate and caused 100% mortality within 24 h following bath challenge of red tilapia with three different doses. The non-Rhizoid isolate (CUVET1201) was avirulent to red tilapia fry. Both morphotypes adhered to and persisted in tilapia similarly at 0.5 and 6 h post-challenge as determined by whole fish bacterial loads. At 24 and 48 h post-challenge, fry challenged with the Rhizoid morphotype exhibited significantly higher bacterial loads than the non-Rhizoid morphotype. The results suggested that an inability of the non-Rhizoid morphotype to persist in tilapia fry may explain lack of virulence.
Ha Thanh Dong - One of the best experts on this subject based on the ideXlab platform.
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virulence assay of Rhizoid and non Rhizoid morphotypes of flavobacterium columnare in red tilapia oreochromis sp fry
Journal of Fish Diseases, 2016Co-Authors: Ha Thanh Dong, Saengchan Senapin, Benjamin R Lafrentz, Channarong RodkhumAbstract:: Numerous isolates of Flavobacterium columnare were previously recovered from red tilapia, Oreochromis sp., exhibiting columnaris-like disease in Thai farms, and the phenotypic and genetic characteristics were described. The objective of this study was to determine the virulence of two morphotypes (Rhizoid and non-Rhizoid colonies) of F. columnare and to determine their ability to adhere to and persist in red tilapia fry. The results showed that the typical Rhizoid isolate (CUVET1214) was a highly virulent isolate and caused 100% mortality within 24 h following bath challenge of red tilapia with three different doses. The non-Rhizoid isolate (CUVET1201) was avirulent to red tilapia fry. Both morphotypes adhered to and persisted in tilapia similarly at 0.5 and 6 h post-challenge as determined by whole fish bacterial loads. At 24 and 48 h post-challenge, fry challenged with the Rhizoid morphotype exhibited significantly higher bacterial loads than the non-Rhizoid morphotype. The results suggested that an inability of the non-Rhizoid morphotype to persist in tilapia fry may explain lack of virulence.
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Virulence assay of Rhizoid and non‐Rhizoid morphotypes of Flavobacterium columnare in red tilapia, Oreochromis sp., fry
Journal of Fish Diseases, 2015Co-Authors: Ha Thanh Dong, Saengchan Senapin, Benjamin R Lafrentz, Channarong RodkhumAbstract:Numerous isolates of Flavobacterium columnare were previously recovered from red tilapia, Oreochromis sp., exhibiting columnaris-like disease in Thai farms, and the phenotypic and genetic characteristics were described. The objective of this study was to determine the virulence of two morphotypes (Rhizoid and non-Rhizoid colonies) of F. columnare and to determine their ability to adhere to and persist in red tilapia fry. The results showed that the typical Rhizoid isolate (CUVET1214) was a highly virulent isolate and caused 100% mortality within 24 h following bath challenge of red tilapia with three different doses. The non-Rhizoid isolate (CUVET1201) was avirulent to red tilapia fry. Both morphotypes adhered to and persisted in tilapia similarly at 0.5 and 6 h post-challenge as determined by whole fish bacterial loads. At 24 and 48 h post-challenge, fry challenged with the Rhizoid morphotype exhibited significantly higher bacterial loads than the non-Rhizoid morphotype. The results suggested that an inability of the non-Rhizoid morphotype to persist in tilapia fry may explain lack of virulence.
Robert Scheuerlein - One of the best experts on this subject based on the ideXlab platform.
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germination in spores of dryopteris filix mas regulation of Rhizoid elongation as a second phytochrome mediated response
Physiologia Plantarum, 2008Co-Authors: Hiroko Yatsuhashi, Stefan Turnwald, Robert ScheuerleinAbstract:Spore germination in Dryopteris filix-mas occurs via a cascade of cellular responses, and chlorophyll formation, mitosis or Rhizoid elongation are commonly used as parameters to determine spore germination. Detailed investigations of these parameters led to the hypothesis that they are regulated by different, independent phytochrome-mediated responses. This concept could be confirmed, as is described in this paper which demonstrates that perception of light via phytochrome occurs within two different phases separated in time. Presence of the far-red absorbing phytochrome form, Pfr, for 36 h, induces chlorophyll formation and the first unequal cell division, by which a Rhizoid initial and a protonemal initial are formed (first phytochrome-mediated response). However, Rhizoid elongation requires a second period of Pfr, presence (second phytochrome-mediated response). There is a clear temporal distinction between the first and the second phytochrome-mediated response with respect to the coupling of Pfr to the transduction chain; Pfr is unable to induce Rhizoid growth until 60 h after the start of the first red irradiation. The effectivity of Pfr for inducing the second response shows an optimum at ca 96 h after the beginning of the presence of Pfr; thereafter, it declines slowly. The fluence-response relationship and the presence of red/far-red reversibility demonstrate that Rhizoid elongation is a low-fluence response mediated by phytochrome and is independent of the first phytochrome response.
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phytochrome dependent modulation and re induction of growth of the first Rhizoid in dryopteris paleacea sw
Planta, 1999Co-Authors: Stefan Turnwald, Robert Scheuerlein, Masaki FuruyaAbstract:Phytochrome-dependent growth in Dryopteris paleacea Sw. was investigated in young, developing gametophytes with respect to formation and differentiation of Rhizoids. Under continuous red light (Rc), the first Rhizoids grew synchronously by tip elongation at a constant rate of 240 μm · d−1 until formation and outgrowth of the second Rhizoid. Cessation of growth of the first Rhizoids and outgrowth of the second Rhizoids showed a correlation in time assumed to be mediated by intercellular signaling. The first Rhizoids showed two modes of response to actinic irradiations: (i) modulation of Rhizoid growth, and (ii) re-induction of growth in non-growing Rhizoids. In the former, the promotory effect of actinic irradiations on Rhizoids pre-cultured under Rc determined both the time for which Rhizoids continued to grow after transfer into darkness and the final Rhizoid length. In the latter, re-induced growth was studied using non-growing Rhizoids which were obtained after irradiation with a far-red light (FR) pulse at the end of the pre-culture in Rc and transfer into darkness for 3 d to stop growth. Re-induction of growth occurred with a lag phase of 36 to 48 h after formation of the FR-absorbing form of phytochrome (Pfr) by a red light (R) pulse. From the incomplete R/FR reversibility it is evident that, here, coupling of Pfr to signal transduction is possible within minutes. Re-induction of growth possesses the advantage that the effect of actinic irradiations can be studied as an all-or-none response at the level of single gametophytes in future experiments. The present results clearly indicate that the developmental stage of the whole gametophyte, i.e. temporal and spatial patterns undergone during development, affects the regulation of Rhizoid growth by the external factor light.
Kazuo Okuda - One of the best experts on this subject based on the ideXlab platform.
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inducible growth mode switches influence valonia Rhizoid differentiation
Protoplasma, 2013Co-Authors: Paul Rommel Elvira, Satoko Sekida, Kazuo OkudaAbstract:Cell differentiation and cell type commitment are an integral part of plant growth and development. Investigations on how environmental conditions affect the formation of shoots, roots, and Rhizoids can help illustrate how plants determine cell fate and overall morphology. In this study, we evaluated the role of substratum and light on Rhizoid differentiation in the coenocytic green alga, Valonia aegagropila. Elongating Rhizoids displayed varying growth modes and cell shape upon exposure to different substrata and light conditions. It was found that soft substrata and dark incubation promoted Rhizoid elongation via tip growth while subsequent exposure to light prevented tip growth and instead induced swelling in the apical region of Rhizoids. Swelling was accompanied by the accumulation of protoplasm in the Rhizoid tip through expansion of the cell wall and uninhibited cytoplasmic streaming. Subsequent diffuse growth led to the transformation from slender, rod-shaped Rhizoids into spherical thallus-like structures that required photosynthesis. Further manipulation of light regimes caused vacillating cell growth redirections. An elongating V. aegagropila Rhizoid cell thus appears capable of growth mode switching that is regulated by immediate environmental conditions thereby influencing ultimate cell shape and function. This is the first description of inducible, multiple growth mode shifts in a single intact plant cell that directly impact its differentiation.
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Rhizoid formation in valonia siphonocladales chlorophyceae
Phycologia, 2012Co-Authors: Paul Rommel Elvira, Satoko Sekida, Kazuo OkudaAbstract:Elvira P.R., Sekida S. and Okuda K. 2012. Rhizoid formation in Valonia (Siphonocladales, Chlorophyceae). Phycologia 51: 391–402. DOI: 10.2216/11-31.1 Rhizoids were artificially induced by the contact or approach of substrata toward Valonia macrophysa, V. fastigiata and V. aegagropila cell surfaces. A single, spherical cell produced Rhizoids locally at the portion that contacted with a glass coverslip, a sheet of cellophane or surface of another Valonia cell. Local induction of Rhizoid formation did not always require direct contact with substrata: occurring when two living cells were placed apart but closer than 0.5 mm. Induction of Rhizoid formation required continuous contactless exposure to a substratum for at least 48 h. In these cases, amorphous materials were secreted to external surfaces and accumulated in the space between two adjacent cells, but when washed out, the number of Rhizoids induced decreased remarkably. The amorphous materials were stained with periodic-acid Schiff's and Alcian Blue an...
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cellular morphogenesis in valonia sp with emphasis on the formation of lenticular and Rhizoid cells
黒潮圏科学, 2009Co-Authors: Alex Pulvinar Camaya, Kazuo OkudaAbstract:The unspecified macrophyte Valonia sp. obtained from Bicol Region, the Philippines portrays two distinct types of cell divisions. Higher light intensity induced lenticular cells, whereas lower light intensity produced Rhizoid cells, which varied in time and structure. These initiated at stage I where chloroplasts assembled roughly at the indefinite surface of a cell. Microtubules (MTs) at the protoplasmic assembly appeared to curve and overlap to each other. At stage II a disc-shaped assembly of protoplasm was transformed where radial MT arrays extended from the periphery to the central area of the protoplasmic assembly. In stage III the aggregation of protoplasm stopped, and the average diameter of lenticular cells was ca. 1 mm whereas Rhizoid cells were ca. 0.1 mm in diameter. Short but dense cortical MTs were arranged randomly all over the protoplasmic aggregations, followed by the depolymerization of MTs. In stage IV septum walls formed to divide lenticular cells or Rhizoid cells from the mother cells. Densely crammed MTs were evenly dispersed all over lenticlular and Rhizoid cells. Then in stage V juvenile cells started to puff out in lenticular cells and likewise elongated for Rhizoid cells. New parallel arrays of MTs were formed from the base towards the apex portion of these new cells. Furthermore, the maximum attainable height measured about 2 mm in lenticular cells, while it was about 1.4 mm for Rhizoid cells. Lenticular and Rhizoid cells tended to develop near the zones of both ends of mother cells. keywords: cytomorphogenesis, cytoskeleton, immunofluorescent microscopy, lenticular cell, microtubule, protoplasmic aggregation, Rhizoid cell, Valonia
