• ALGAE
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• v.21 no.3
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• pp.323-332
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• 2006

Mitochondrial distribution and abundance were assessed during the growth of apical and subapical cells in the red algae Colaconema caespitosum (J. Agardh) Jackelman, Stegenga and Bolton and Antithamnion cruciatum (C. Agardh) Nägeli after staining with 3,3’-dihexyloxacarbocyanine iodide [DiOC6(3)] and 2,4’-dimethylaminostyryl-Nethylpyridinium iodide (DASPEI). In fully elongate apical cells of C. caespitosum there were 100-120 mitochondria. During apical cell enlargement and division there is a doubling and then halving of the mitochondrial numbers. Apical cells prior to cytokinesis in young filaments are smaller than in mature filaments (ca. 50 and 100 μm long, respectively) and have fewer mitochondria (ca. 100 and 120 mitochondria per cell, respectively). In older vegetative cells mitochondria tend to aggregate at opposite ends of the cells with some mitochondria associated with the central nucleus or at points of apparent branch initiation. There is a greater density of mitochondria in apical cells of smaller versus larger plants (one mitochondrion per 6.3 μm3 and 9.8 μm3, respectively), suggesting that apical cells of younger plants may be more metabolically active. Male and female gametophytic thalli of Antithamnion cruciatum had similar numbers of mitochondria in apical cells of indeterminate axes, as did gametophytic and sporophytic thalli. There were about 40-50 mitochondria in fully elongated apical cells with about half this number in newly divided apical and subapical cells. Apical cells of determinate branches had more mitochondria (60-77) than indeterminate branches (60-70 vs. 40-50). In both species and in all cell types mitochondrial numbers were highly correlated with cell size.

• International Journal of Oral Biology
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• v.37 no.1
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• pp.37-41
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• 2012

Pancreatic acinar cells exhibit a polarity that is characterized by the localization of secretory granules at the apical membrane. However, the factors that regulate cellular polarity in these cells are not well understood. In this study, we investigated the effect of Mist1, a basic helix-loop-helix transcription factor, on the cellular architecture of pancreatic acinar cells. Mist1-null mice displayed secretory granules that were diffuse throughout the pancreatic acinar cells, from the apical to basolateral membranes, whereas Mist1 heterozygote mice showed apical localization of secretory granules. Deletion of the Mist1 gene decreased the expression of type 3 inositol 1,4,5-triphosphate receptors ($IP_3R$) but did not affect apical localization and expression of $IP_3R2$. Mist1-null mice also displayed an increase in luminal areas and an increase in the expression of zymogen granules in pancreatic acinar cells. These results suggest that Mist1 plays a critical role in polar localization of cellular organelles and in maintaining cellular architecture in mouse pancreatic acinar cells.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.4
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• pp.311-318
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• 2000

We cultured the rabbit inner medullary collecting duct (IMCD) cells as monolayers on collagen-coated membrane filters, and investigated distribution of the P2Y receptors by analyzing nucleotide-induced short circuit current $(I_{sc})$ responses. Exposure to different nucleotides of either the apical or basolateral surface of cell monolayers stimulated $I_{sc}.$ Dose-response relationship and cross-desensitization studies suggested that at least 3 distinct P2Y receptors are expressed asymmetrically on the apical and basolateral membranes. A $P2Y_2-like$ receptor, which responds to UTP and ATP, is expressed on both the apical and basolateral membranes. In addition, a uracil nucleotide receptor, which responds to UDP and UTP, but not ATP, is expressed predominantly on the apical membrane. In contrast, a $P2Y_1-like$ receptor, which responds to ADP and 2-methylthio-ATP, is expressed predominantly on the basolateral membrane. These nucleotides stimulated intracellular cAMP production with an asymmetrical profile, which was comparable to that in the stimulation of $I_{sc}.$ Our results suggest that the adenine and uracil nucleotides can interact with different P2Y nucleotide receptors that are expressed asymmetrically on the apical and basolateral membranes of the rabbit IMCD cells, and that both cAMP- and $Ca^{2+}-dependent$ signaling mechanisms underlie the stimulation of $I_{sc}$.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.25-31
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• 1999

Developmental morphology of the red alga, Osmundea crispa (Hollenberg) Nam from California was studied on the basis of liquid-preserved and herbarium specimens. Vegetative axial segment of the species produces two pericentral cells and one trichoblast. Spermatangial filaments (branches) are derived from apical and epidermal cells in pocket-shaped apical pit with an ostiole-like upper opening. Procarp-bearing segment of female trichoblast produces five pericentral cells, of which the fifth functions as supporting cell of carpogonial branch. Tetrasporangial production occurs in random epidermal cells in apical pit of branchlets, and two presporangial cover cells show parallel arrangement to stichidial axis. As this vegetative and reproductive development is included in the generic delineation of Osmundea Stackhouse, O. crispa among the known Osmundea species is characterized by habit forming compact cushion-like clump with angular to terete thallus. It is also distinguished from O. hybrida (AP. de Candolle) Nam without the compressed thallus by the number of pericentral cells in procarp-bearing segment and shape of spermatangial pit. Taxonomic implication of the shape of spermatangial pit is also included.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.3
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• pp.231-241
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• 2001

The mammalian cortical collecting duct (CCD) plays a major role in regulating renal NaCl reabsorption, which is important in $Na^+$ and $Cl^-$ homeostasis. The M-1 cell line, derived from the mouse cortical collecting duct, has been used as a mammalian model of the study on the electrolytes transport in CCD. M-1 cells were grown on collagen-coated permeable support and short circuit current $(I_{sc})$ was measured. M-1 cells developed amiloride-sensitive current $5{\sim}7$ days after seeding. Apical and basolateral addition of ATP induced increase in $I_{sc}$ in M-1 cells, which was partly retained in $Na^+-free$ or $Cl^--free$ solution, indicating that ATP increased $Na^+$ absorption and $Cl^-$ secretion in M-1 cells. $Cl^-$ secretion was mediated by the activation of apical cystic fibrosis transmembrane regulator (CFTR) chloride channels and $Ca^{2+}-activated$ chloride channels, but $Na^+$ absorption was not mediated by activation of epithelal sodium channel (ENaC). ATP increased cAMP content in M-1 cells. The RT-PCR analysis demonstrated that M-1 cells express $P2Y_2,\;P2X_3\;and\;P2Y_4$ receptors. These results showed that ATP regulates $Na^+$ and $Cl^-$ transports via multiple P2 purinoceptors on the apical and basolateral membranes in M-1 cells.

• ALGAE
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• v.20 no.4
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• pp.315-324
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• 2005

Anatomical organization of Stoechospermum marginatum reveals small cortical cells with moderately dense cytoplasm, overlying a multilayered medulla comparatively poor in cytoplasmic contents. The anticlinal walls of cortical cells show local thickenings rich in alginic acids. Sori form on both thallus surfaces and show tetrasporangia, paraphyses and sterile-cells. The unicellular paraphyses are rich in sulphated polysaccharides whereas multicellular ones have abundance of not only polysaccharides, but also of vacuoles and phenols. The sterile-cells are modified cortical cells present on either side of the tetrasporangium and bear cytoplasmic strands towards soral cavity. Various stages of tetrasporogenesis are seen in a single sorus. The developing tetrasporangium shows a two layered wall, where the outer one is rich in alginic acid and inner has sulphated polysaccharides. An apical pad aids tetraspore release. Also involved in the release process are sterile-cells, paraphyses and polysaccharides.

• Applied Microscopy
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• v.23 no.1
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• pp.1-14
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• 1993

The present study was carried out to analyze the evidence of membrane recycling, and the regulation of cellular transport by dynamic changes in apical membrane area that functionally interacts with the number of cytoplasmic vesicles. Under scanning electron micrographs, turtle bladder mucosa contain three main type of cells; granular cells and carbonic anhydrase (CA)-rich cells, deviding into a and b type of epithelial cell. The granular cell is the majority cell type of the mucosa comprising 80% of the total cell number. The remaining 20% of the cells are characteristically rich in carbonic anhydrase. Uptake of HRP was detected in the most vacuoles or tubulovesicles in both type of CA-rich cells in the turtle bladder, indicating that the part of plasma membrane was internalized in the apical cytoplasmic vacuoles. It seems quite likely that CA-rich cells possess intracellular vesicles carrying proton pumps which are recycling back to the apical plasma membrane. In turtle bladder, the granular cells actively secrete large quantities of mucin and other proteins by an exocytotic mechanism in an apparently constitutive fashion. The possibility that bladder epithelial cells secrete mucin via a regulated secretory pathway has not been rigorously examined and much is still to be determined about these issues from this cell type.

• Journal of Species Research
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• v.11 no.4
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• pp.321-329
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• 2022

Four species of cyanobacteria that are unrecorded in Korea were isolated from freshwater and brackish water. These four species are Laspinema thermale of Laspinemaceae, Planktothricoides raciborskii and Planktothrix spiroides of Microcoleaceae, and Cephalothrix lacustris of Phormidiaceae, all belonging to the order Oscillatoriales. Laspinema thermale is morphologically characterized as apical cells that are longer than other cells. In this strain, the similarity of the 16S rRNA gene sequence with the previously reported L. thermale strains were 99.30-99.50%. Planktothricoides raciborskii, which is characterized by bluntly conical morphology of apical cells, showed 98.80-99.50% of similarity of the 16S rRNA gene sequence to the previously reported P. raciborskii strains. Planktothrix spiroides are characterized by floating due to gas vacuoles. In this strain, the similarity of the 16S rRNA gene sequence with the previously reported P. spiroides strains were 99.80-99.90%. Cephalothrix lacustris, characterized by having calyptra in apical cells, showed 99.80-99.90% similarity of the 16S rRNA gene sequence to previously reported C. lacustris strains. Also, these species were clustered in the same clade in phylogenetic analysis using 16S rRNA gene sequences with each corresponding species.

• Restorative Dentistry and Endodontics
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• v.26 no.2
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• pp.124-126
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• 2001

A case of an unicystic ameloblastoma of the mandible presenting as an apical periodontal cyst was reported. The lesion showed an unilocular radiolucency with well delineated border. Histologic examination revealed that a fibrous cyst wall with a lining that consists of partially of ameloblastic epithelium. The overlying epithelial cells are loosely cohesive and resemble stellate reticulum. The fibrous cyst wall of the cyst is infiltrated by typical follicular ameloblastoma. but devoid of inflammatory reaction in the cystic wall. Some considerations regarding differential diagnosis. pathogenesis and biologic behaviour of the lesion were discussed.

• Molecules and Cells
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• v.19 no.3
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• pp.342-349
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• 2005

Cytokinins are adenine derivatives that regulate numerous plant growth and developmental processes, including apical and floral meristem development, stem growth, leaf senescence, apical dominance, and stress tolerance. However, not much is known about how cytokinin biosynthesis and metabolism is regulated. We identified a novel Arabidopsis gene, ALL, encoding an aldolase-like enzyme that regulates cytokinin signaling. An Arabidopsis mutant, all-1D, in which ALL is activated by the nearby insertion of the 35S enhancer, exhibited extreme dwarfism with rolled, dark-green leaves and reduced apical dominance, symptomatic of cytokinin-overproducing mutants. Consistent with this, ARR4 and ARR5, two representative primary cytokinin-responsive genes, were significantly induced in all-1D. Whereas SHOOT MERISTEMLESS (STM) and KNAT1, which regulate meristem development, were also greatly induced, expression of REV and PHV that regulate lateral organ polarity was inhibited. ALL encodes an aldolase-like enzyme that belongs to the HpcH/HpaI aldolase family in prokaryotes and is down-regulated by exogenous cytokinin, possibly through a negative feedback pathway. We propose that ALL is involved in cytokinin biosynthesis or metabolism and acts as a positive regulator of cytokinin signaling during shoot apical meristem development and determination of lateral organ polarity.