NOTE ON THE NATURE OF THE CURRENT OF INJURY IN TISSUES
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Leading off from two places on the same cell (of Nitella) with 0.001 M KCl we observe that a cut produces only a temporary negative current of injury. If we lead off with 0.001 M KCl from any cell to a neighboring cell we find that when sap comes out from the cut cell and reaches the neighboring intact cell a lasting negative "current of injury" is produced. This depends on the fact that the intact cell is in contact with sap at one point and with 0.001 M KCl at the other (this applies also to tissues composed of small cells). If we employ 0.1 M KCl in place of 0.001 M the current of injury with a single cell is positive (and is more lasting when a neighboring cell is present). Divergent results obtained with tissues and single cells may be due in part to these factors.Keywords:
Nitella
Cell injury
Leading off from two places on the same cell (of Nitella) with 0.001 M KCl we observe that a cut produces only a temporary negative current of injury. If we lead off with 0.001 M KCl from any cell to a neighboring cell we find that when sap comes out from the cut cell and reaches the neighboring intact cell a lasting negative "current of injury" is produced. This depends on the fact that the intact cell is in contact with sap at one point and with 0.001 M KCl at the other (this applies also to tissues composed of small cells). If we employ 0.1 M KCl in place of 0.001 M the current of injury with a single cell is positive (and is more lasting when a neighboring cell is present). Divergent results obtained with tissues and single cells may be due in part to these factors.
Nitella
Cell injury
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Cell injury
Cell mediated immunity
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The results of a cytotaxonomical research for Nitella flexilis (n=12, from four habitats), Nitella inokasiraensis (n=6) and Nitella opaca (n=6) are reported. Special relations between the centromere positions of the chromosomes of N. flexilis complex were found, and the basic number (x=3) for the section Nitella is suggested. The patterns of the karyotypes of the 3 species and 1 form were analysed.
Nitella
Section (typography)
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The normal cell maintains a steady state, termed homeostasis, in which the internal milieu of the cell is kept within physiological parameters. The response of a cell to any change in its environment constitutes the pathophysiological basis of clinical symptoms. When cells are faced with physiological or pathological stress they respond in several ways, collectively known as cellular adaptation. When the capacity of the cell to adapt is exceeded, then the cell undergoes a series of changes referred to as cell injury. The degree of injury dictates whether the cell will recover (i.e. reversible cell injury) or progress to cell death (i.e. irreversible cell injury). The effect on the tissue will depend on the duration of the injury, the nature of the injurious agent, the proportion and types of cells affected and the ability of the tissue to regenerate.
Cell injury
Cell type
Cell damage
Homeostasis
Pathophysiology
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In Nitella flexilis, a species belonging to the section Anarthrodactylae of the genus Nitella (Characeae), some mature cells, with the exception of those of the nodal complex and the rhizoid, show numerous spherical vacuoles occupying the entire central region of the cell. These vacuoles are fairly uniform in size measuring 30–40 μm in diameter. Evidence is presented from investigations with the light and electron microscopes suggesting that some mature cells of a certain group of Nitella species may not have a huge central vacuole. Vacuolation in young cells of the apex apparently begins by progressive dilation of the endoplasmic reticulum. The Golgi complex may also be involved in vacuolation. The necessity for re-examination of certain biological activities in the giant internode cell is explored.
Nitella
Rhizoid
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When an internodal cell of Nitella axilliformis that had been treated with 10 mM KCl and 1 mM EGTA was examined for transcellular osmosis, an increase in the cytosolic concentration of Ca2+ on the endoosmotic side was observed, as was the case in Nitella flexilis even though the increase was much smaller in Nitella axilliformis. The hydration-induced calcium release (HICR) was also observed in other species of Characeae, namely, Chara corallina and Nitellopsis obtusa. HICR was also demonstrated in cytoplasm isolated from Nitella axilliformis and Chara corallina as from Nitella flexilis. Thus, it appears that HICR is not specific to Nitella flexilis but may be a general phenomenon in Characeae.
Nitella
Chara
Cytoplasmic streaming
Rhizoid
Elodea canadensis
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We report a new taxonomic entity of Nitella megacephala sp. nov. (Charales, Charophyceae) from Korea. The characean algae collected from two sites (Haenam-gun and Kangjin-gun) had distinctive morphological characteristics representing a new Nitella species. Those samples showed a light-green color in gross morphology and a plant body length up to 13 cm. Moreover, the two-celled dactyls and head formation differed clearly from closely related Nitella species (N. moriokae, N. spiciformis, and N. translucens). From a molecular phylogenetic analysis of rbcL DNA sequences, Nitella megacephala sp. nov formed a single clade with N. translucens, N. moriokae and N. spiciformis, and was distantly related to those three species as a sister taxon. In the terms of interspecific sequence variation, Nitella megacephala showed 3.2–5.5% pairwise distance values with sister groups in phylogenetic tree (N. translucens, N. moriokae and N. spiciformis) and 3.2–9.1% with other of Nitella species. In contrast, its sister group species differed 0.3–1.7% at the interspecific level. These unique morphological and molecular taxonomic characteristics clearly support the establishment of this taxonomic entity as a new species in the genus Nitella (Nitella megacephala sp. nov.)
Nitella
Sister group
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LDL can injure endothelial cells in culture. HDL can inhibit this injurious effect of DDL. This effect of LDL seems to be independent of the LDL-receptor pathway since LDL-receptor negative cells were also injured. Ehdocytotic uptake of LDL appear not to be necessary for the DDL- induced cell injury to occur because LDL can injure both endothelial cells and erythrocytes at 4°C. By using radioactive 125I-DDL an increasing amount of 125I-LDL was shown to be associated with the cell with increasing concentrations of 125I-LDL in the incubation medium. A corresponding increase in cell injury as measured by 51Cr-release was observed. Presence of HDL in the incubation medium reduced both the cell associated radioactivity and the 51Cr-release. Thus, a relationship between the amount of 125I-DDL associated with the cell and the degree of cell injury was present. In conclusion, association of DDL to the cell surface seems to be closely related to the mechanism by which DDL can induce cell injury. Any kind of endocytotic uptake of DDL is not a prerequisite for the occurrence of DDL-mediated cell injury.
Cell injury
Incubation period
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New records to the Characean flora of Sicily are presented. Five species (Chara baltica, C. conimbrigensis, C. oedophylla, Nitella gracilis, Tolypella salina) are new to Sicily, two of them being also new to Italy (Chara conimbrigensis, C. oedophylla). Two species are confirmed for Sicily (Chara aspera, Nitella opaca), three (Chara braunii, C. canescens, Nitella capillaris) are rare taxa. The Characean flora of Sicily, updated with these records, currently includes 25 species, distributed in four genera: Chara (13 species), Nitella (eight species), Tolypella (three species) and Lamprothamnium (one species).
Nitella
Chara
Flora
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We found previously that the cytoplasmic drop isolated from internodal cells of Nitella flexilis releases Ca2+ in response to hypotonic treatment and named the phenomenon hydration-induced Ca2+ release (HICR). The HICR is assumed to be a result of activation of Ca2+ permeable channels in the membrane of Ca2+ stores in a stretch-activated manner. To prove this idea, mechanical stimulus was applied to the drop by means of shooting isotonic/hypnotic medium or silicon oil into the drop, or compressing the drop. All these mechanical stimuli induced a rapid increase in the Ca2+ concentration of the drop. The chloroplast fraction isolated from the cytoplasmic drop released Ca2+ on compression, while the chloroplast-free cytoplasm did not. In Chara corallina, the cytoplasmic drop, which shows a very weak HICR, also responded weakly to the mechanical stimulus, but the chloroplast fraction was inert. When chloroplasts from Chara were added to the chloroplast-free cytoplasm of N. flexilis, the cytoplasm recovered the mechanoresponse. Starch grains were as effective as chloroplasts. The data indicate that Ca2+ permeable channels in the membrane of Ca2+ stores in N. flexilis are really mechano-sensitive.
Nitella
Chara
Cytoplasmic streaming
Chloroplast stroma
Elodea canadensis
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