This page has only limited features, please log in for full access.

Unclaimed
Panagiotis Apostolakos
Section of Botany, Department of Biology, National and Kapodistrian University of Athens, 15781 Athens, Greece

Basic Info

Basic Info is private.

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 03 August 2021 in Journal of Biological Research-Thessaloniki
Reads 0
Downloads 0

Background Although the cellulose microfibril organization in guard cell (GC) walls play a crucial role in the mechanism of the stomatal function, recent work showed that matrix cell wall materials are also involved. Especially in the kidney-shaped stomata of the fern Asplenium nidus, callose actively participates in the mechanism of opening and closure of the stomatal pore. Scope The present review briefly presents and discusses recent findings concerning the distribution and role of callose in the kidney-shaped stomata of the dicotyledon Vigna sinensis as well as in the dumbbell-shaped stomata of the monocotyledon Zea mays. Conclusion The discussed data support that, in both categories of angiosperm stomata, callose is implicated in the mechanism of stomatal pore formation and stomata function by locally affecting the mechanical properties of the GC cell walls.

ACS Style

Panagiotis Apostolakos; Eleni Giannoutsou; Basil Galatis. Callose: a multifunctional (1, 3)-β–d-glucan involved in morphogenesis and function of angiosperm stomata. Journal of Biological Research-Thessaloniki 2021, 28, 1 .

AMA Style

Panagiotis Apostolakos, Eleni Giannoutsou, Basil Galatis. Callose: a multifunctional (1, 3)-β–d-glucan involved in morphogenesis and function of angiosperm stomata. Journal of Biological Research-Thessaloniki. 2021; 28 (1):1.

Chicago/Turabian Style

Panagiotis Apostolakos; Eleni Giannoutsou; Basil Galatis. 2021. "Callose: a multifunctional (1, 3)-β–d-glucan involved in morphogenesis and function of angiosperm stomata." Journal of Biological Research-Thessaloniki 28, no. 1: 1.

Journal article
Published: 20 December 2019 in International Journal of Molecular Sciences
Reads 0
Downloads 0

The distribution of highly de-esterified homogalacturonans (HGs) in dividing protodermal cells of the monocotyledon Zea mays, the dicotyledon Vigna sinensis, and the fern Asplenium nidus was investigated in order to examine whether the cell wall region adjoining the preprophase band (PPB) is locally diversified. Application of immunofluorescence revealed that de-esterified HGs were accumulated selectively in the cell wall adjacent to the PPB in: (a) symmetrically dividing cells of stomatal rows of Z. mays, (b) the asymmetrically dividing protodermal cells of Z. mays, (c) the symmetrically dividing guard cell mother cells (GMCs) of Z. mays and V. sinensis, and (d) the symmetrically dividing protodermal cells of A. nidus. A common feature of the above cell types is that the cell division plane is defined by extrinsic cues. The presented data suggest that the PPB cortical zone-plasmalemma and the adjacent cell wall region function in a coordinated fashion in the determination/accomplishment of the cell division plane, behaving as a continuum. The de-esterified HGs, among other possible functions, might be involved in the perception and the transduction of the extrinsic cues determining cell division plane in the examined cells.

ACS Style

Eleni Giannoutsou; Basil Galatis; Panagiotis Apostolakos. De-Esterified Homogalacturonan Enrichment of the Cell Wall Region Adjoining the Preprophase Cortical Cytoplasmic Zone in Some Protodermal Cell Types of Three Land Plants. International Journal of Molecular Sciences 2019, 21, 81 .

AMA Style

Eleni Giannoutsou, Basil Galatis, Panagiotis Apostolakos. De-Esterified Homogalacturonan Enrichment of the Cell Wall Region Adjoining the Preprophase Cortical Cytoplasmic Zone in Some Protodermal Cell Types of Three Land Plants. International Journal of Molecular Sciences. 2019; 21 (1):81.

Chicago/Turabian Style

Eleni Giannoutsou; Basil Galatis; Panagiotis Apostolakos. 2019. "De-Esterified Homogalacturonan Enrichment of the Cell Wall Region Adjoining the Preprophase Cortical Cytoplasmic Zone in Some Protodermal Cell Types of Three Land Plants." International Journal of Molecular Sciences 21, no. 1: 81.

Original article
Published: 30 August 2019 in Protoplasma
Reads 0
Downloads 0

This article deals with the distribution of callose and of the homogalacturonan (HG) epitopes recognized by LM20, JIM5, and 2F4 antibodies in cell walls of differentiating and functioning stomatal complexes of the monocotyledon Zea mays and the dicotyledon Vigna sinensis. The findings revealed that, during stomatal development, in these plant species, callose appears in an accurately spatially and timely controlled manner in cell walls of the guard cells (GCs). In functioning stomata of both plants, callose constitutes a dominant cell wall matrix material of the polar ventral cell wall ends and of the local GC cell wall thickenings. In Zea mays, the LM20, JIM5, or 2F4 antibody-recognized HG epitopes were mainly located in the expanding cell wall regions of the stomatal complexes, while in Vigna sinensis, they were deposited in the local cell wall thickenings of the GCs as well as at the ledges of the stomatal pore. Consideration of the presented data favors the view that in the stomatal complexes of the monocotyledon Z. mays and the dicotyledon V. sinensis, the esterified HGs contribute to the cell wall expansion taking place during GC morphogenesis and the opening of the stomatal pore. Besides, callose and the highly de-esterified HGs allow to GC cell wall regions to withstand the mechanical stresses exerted during stomatal function.

ACS Style

Eleni Giannoutsou; P. Sotiriou; T. L. Nikolakopoulou; B. Galatis; P. Apostolakos. Callose and homogalacturonan epitope distribution in stomatal complexes of Zea mays and Vigna sinensis. Protoplasma 2019, 257, 141 -156.

AMA Style

Eleni Giannoutsou, P. Sotiriou, T. L. Nikolakopoulou, B. Galatis, P. Apostolakos. Callose and homogalacturonan epitope distribution in stomatal complexes of Zea mays and Vigna sinensis. Protoplasma. 2019; 257 (1):141-156.

Chicago/Turabian Style

Eleni Giannoutsou; P. Sotiriou; T. L. Nikolakopoulou; B. Galatis; P. Apostolakos. 2019. "Callose and homogalacturonan epitope distribution in stomatal complexes of Zea mays and Vigna sinensis." Protoplasma 257, no. 1: 141-156.

Research paper
Published: 16 December 2017 in Plant Biology
Reads 0
Downloads 0

The distribution of homogalacturonans (HGAs) displaying different degrees of esterification as well as of callose was examined in cell walls of mature pavement cells in two angiosperm and two fern species. We investigated whether local cell wall matrix differentiation may enable pavement cells to respond to mechanical tension forces by transiently altering their shape. HGA epitopes, identified with 2F4, JIM5 and JIM7 antibodies, and callose were immunolocalised in hand‐made or semithin leaf sections. Callose was also stained with aniline blue. The structure of pavement cells was studied with light and transmission electron microscopy (TEM). In all species examined, pavement cells displayed wavy anticlinal cell walls, but the waviness pattern differed between angiosperms and ferns. The angiosperm pavement cells were tightly interconnected throughout their whole depth, while in ferns they were interconnected only close to the external periclinal cell wall and intercellular spaces were developed between them close to the mesophyll. Although the HGA epitopes examined were located along the whole cell wall surface, the 2F4‐ and JIM5‐ epitopes were especially localised at cell lobe tips. In fern pavement cells, the contact sites were impregnated with callose and JIM5‐HGA epitopes. When tension forces were applied on leaf regions, the pavement cells elongated along the stretching axis, due to a decrease in waviness of anticlinal cell walls. After removal of tension forces, the original cell shape was resumed. The presented data support that HGA epitopes make the anticlinal pavement cell walls flexible, in order to reversibly alter their shape. Furthermore, callose seems to offer stability to cell contacts between pavement cells, as already suggested in photosynthetic mesophyll cells.

ACS Style

P. Sotiriou; Eleni Giannoutsou; E. Panteris; B. Galatis; P. Apostolakos. Local differentiation of cell wall matrix polysaccharides in sinuous pavement cells: its possible involvement in the flexibility of cell shape. Plant Biology 2017, 20, 223 -237.

AMA Style

P. Sotiriou, Eleni Giannoutsou, E. Panteris, B. Galatis, P. Apostolakos. Local differentiation of cell wall matrix polysaccharides in sinuous pavement cells: its possible involvement in the flexibility of cell shape. Plant Biology. 2017; 20 (2):223-237.

Chicago/Turabian Style

P. Sotiriou; Eleni Giannoutsou; E. Panteris; B. Galatis; P. Apostolakos. 2017. "Local differentiation of cell wall matrix polysaccharides in sinuous pavement cells: its possible involvement in the flexibility of cell shape." Plant Biology 20, no. 2: 223-237.

Journal article
Published: 29 April 2016 in Protoplasma
Reads 0
Downloads 0

Reactive oxygen species (ROS) are emerging players in several biological processes. The present work investigates their potential involvement in plant cytokinesis by the application of reagents disturbing ROS homeostasis in root-tip cells of Triticum turgidum. In particular, the NADPH-oxidase inhibitor diphenylene iodonium, the ROS scavenger N-acetyl-cysteine, and menadione that leads to ROS overproduction were used. The effects on cytokinetic cells were examined using light, fluorescence, and transmission electron microscopy. ROS imbalance had a great impact on the cytokinetic process including the following: (a) formation of atypical “phragmoplasts” incapable of guiding vesicles to the equatorial plane, (b) inhibition of the dictyosomal and/or endosomal vesicle production that provides the developing cell plates with membranous and matrix polysaccharidic material, (c) disturbance of the fusion processes between vesicles arriving on the cell plate plane, (d) disruption of endocytic vesicle production that mediates the removal of the excess membrane material from the developing cell plate, and (e) the persistence of large callose depositions in treated cell plates. Consequently, either elevated or low ROS levels in cytokinetic root-tip cells resulted in a total inhibition of cell plate assembly or the formation of aberrant cell plates, depending on the stage of the affected cytokinetic cells. The latter failed to expand towards cell cortex and hence to give rise to complete daughter cell wall. These data revealed for the first time the necessity of ROS homeostasis for accomplishment of plant cytokinesis, since it seems to be a prerequisite for almost every aspect of this process.

ACS Style

Pantelis Livanos; Basil Galatis; Hartmut Quader; Panagiotis Apostolakos. ROS homeostasis as a prerequisite for the accomplishment of plant cytokinesis. Protoplasma 2016, 254, 569 -586.

AMA Style

Pantelis Livanos, Basil Galatis, Hartmut Quader, Panagiotis Apostolakos. ROS homeostasis as a prerequisite for the accomplishment of plant cytokinesis. Protoplasma. 2016; 254 (1):569-586.

Chicago/Turabian Style

Pantelis Livanos; Basil Galatis; Hartmut Quader; Panagiotis Apostolakos. 2016. "ROS homeostasis as a prerequisite for the accomplishment of plant cytokinesis." Protoplasma 254, no. 1: 569-586.

Journal article
Published: 05 October 2005 in Protoplasma
Reads 0
Downloads 0

The effects of aluminium on the actin filament (AF) cytoskeleton of Triticum turgidum meristematic root tip cells were examined. In short treatments (up to 2 h) with 50–1000 μM AlCl3·6H2O, interphase cells displayed numerous AFs arrayed in thick bundles that lined the plasmalemma and traversed the endoplasm in different directions. Measurements using digital image analysis and assessment of the overall AF fluorescence revealed that, in short treatments, the affected cells possessed 25–30% more AFs than the untreated ones. The thick AF bundles were not formed in the Al-treated cells in the presence of the myosin inhibitors 2,3-butanedione monoxime (BDM) and 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-7), a fact suggesting that myosins are involved in AF bundling. In longer Al treatments, the AF bundles were disorganised, forming granular actin accumulations, a process that was completed after 4 h of treatment. In the Al-treated cells, increased amounts of callose were uniformly deposited along the whole surface of the cell walls. In contrast, callose formed local deposits in the Al-treated cells in the presence of cytochalasin B, BDM, or ML-7. These results favour the hypothesis that the actomyosin system in the Al-treated cells, among other roles, participates in the mechanism controlling callose deposition.

ACS Style

G. Frantzios; B. Galatis; P. Apostolakos. Aluminium causes variable responses in actin filament cytoskeleton of the root tip cells of Triticum turgidum. Protoplasma 2005, 225, 129 -140.

AMA Style

G. Frantzios, B. Galatis, P. Apostolakos. Aluminium causes variable responses in actin filament cytoskeleton of the root tip cells of Triticum turgidum. Protoplasma. 2005; 225 (3-4):129-140.

Chicago/Turabian Style

G. Frantzios; B. Galatis; P. Apostolakos. 2005. "Aluminium causes variable responses in actin filament cytoskeleton of the root tip cells of Triticum turgidum." Protoplasma 225, no. 3-4: 129-140.