Search results for "Cell Division"
showing 10 items of 457 documents
Cyanide inhibits respiration yet stimulates aerobic growth of Zymomonas mobilis
2000
Potassium cyanide at submillimolar concentrations (20-500 microM) inhibited the high respiration rates of aerobic cultures of Zymomonas mobilis but, remarkably, stimulated culture growth. In batch culture, after an extended lag phase, exponential growth persisted longer, resulting in higher biomass densities. In aerobic chemostat cultures, elevated biomass concentration was observed in the presence of cyanide. This growth stimulation effect is attributed to decreased production of the inhibitory metabolite acetaldehyde at lowered respiration rates, when more reducing equivalents are channelled to alcohol dehydrogenase. Growth in the presence of cyanide did not alter the membrane cytochrome …
Nuclear involvement of the Cell Division Cycle 48 protein during the plant immune response
2023
The control of protein homeostasis, a balance between their synthesis and degradation, also called proteostasis, is essential for cell survival. Any imbalance of the proteome, for instance triggered by a stress, leads to an accumulation of misfolded proteins leading to proteotoxic stress that can induce cell death. The ubiquitin proteasome system (UPS) is a major actor in the selective degradation of misfolded proteins to preserve proteome balance.The chaperone-like Cdc48 is a member of the AAA+ ATPase enzyme family which isconserved in mammals (VCP), yeasts and plants (Cdc48: Cell Division Cycle 48/p97).Cdc48/VCP is a cytosolic and nuclear protein which segregates misfolded proteins fromsu…
A factor derived from chick embryo retina which inhibits DNA synthesis of retina itself.
1992
Chick embryo retinas contain a peptide factor that inhibits DNA synthesis in explants of chick embryo retina. The inhibitory factor, obtained by acid/ethanol extraction from 15-day-old chick embryo retinas, was partially purified by affinity chromatography on heparin-sepharose CL-6B and gel filtration on Sephadex G-100. The inhibitor reduced DNA synthesis with maximal effects observed in retinal explants from 7 to 8-day-old chick embryos. The inhibitory effect became apparent after 10 h of incubation and reached the maximum levels after 16 h. DNA-inhibiting activity was heat and acid-stable and was destroyed by trypsin and alkaline treatments. The inhibitory effect was observed in retinal e…
Pattern of polyamines and related monoacetyl derivatives in chick embryo retina during development.
1994
Polyamines and related monoacetyl derivatives were studied in chick embryo retina during development (6th-19th day). Putrescine, which is high in the first phase of retinogenesis, is necessary to sustain both tissue proliferation and via N-acetylputrescine, gamma-aminobutyric acid synthesis. A later increase in spermidine and particularly spermine may play a role in the last phase of development when the retina reaches maturation. The presence of N1-acetylspermidine already at the 8th day indicates that in chick embryo retina, putrescine synthesis can depend on two separate pathways. The first involves ornithine decarboxylase activity; the second, spermidine/spermine N1-acetyltransferase an…
The use of morphokinetics as a predictor of embryo implantation.
2011
Background Time-lapse observation presents an opportunity for optimizing embryo selection based on morphological grading as well as providing novel kinetic parameters, which may further improve accurate selection of viable embryos. The objective of this retrospective study was to identify the morphokinetic parameters specific to embryos that were capable of implanting. In order to compare a large number of embryos, with minimal variation in culture conditions, we have used an automatic embryo monitoring system. Methods Using a tri-gas IVF incubator with a built-in camera designed to automatically acquire images at defined time points, we have simultaneously monitored up to 72 individual emb…
Rates of uptake and metabolism of indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid by cultured leaf segments at different stages of developmen…
1987
Immature leaf tissue of Triticum timopheevi Zukh. responded to supplied auxin and showed cell division in culture. The rates of uptake and of metabolism of indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid by such tissues were measured and compared with those of mature auxin-unresponsive tissue. The purpose of these experiments was to determine whether or not the concentration of auxin in cultured mature tissue was a factor limiting the cell division response to auxin. The data indicate that neither alterations in rates of uptake nor alterations in rates of metabolism could explain the loss of responsiveness to auxin which apparently occurs during cell differentiation. The results are…
Patterns of wall synthesis inSaccharomyces cerevisiae
1979
Wall formation inSaccharomyces cerevisiae seems to be the result of two main patterns of wall material deposition: (i) around the whole periphery of the cell in nonbudding ones, and (ii) mainly at the tip of the daughter cell or at the cross wall that separates dividing cells. This interpretation has been obtained following experiments in which RNA or protein synthesis has been inhibited. Under these conditions, glucan formation takes place, and wall thickening is probably due to the accumulation of this polysaccharide. Furthermore, once a pattern of wall deposition has been established, it is not modified by inhibition of RNA or protein synthesis.
Effect of auxin on the mitotic cell cycle in cultured leaf segments at different stages of development in wheat
1987
Young leaves of Triticum timopheevi Zukh. show a defined gradient of development. One-mm-long sections from such leaves were cultured in vitro. At a low concentration of exogenous auxin, cells in the most basal, highly meristematic explants divided readily in culture, but in the absence of auxin they soon ceased dividing and were arrested in G1 and G2 of the mitotic cell cycle. In the region adjoining the meristem, where most cells were arrested in G1, very high concentrations of auxin had to be applied to reinitiate cell division, i.e. stimulate transitions from G1 to S-phase and from G2 to mitosis. Above this potentially auxin-responsive region, which represented less than 50% of the tota…
Regulation of chitin synthase activity inSaccharomyces cerevisiae: Effect of the inhibition of cell division and of synthesis of RNA and protein
1980
The effect of pronase and trypsin on the activation or deactivation (degradation?) of chitin synthase ofSaccharomyces cerevisiae occurs faster in membranous preparations than in toluene-treated cells. When the temperature is raised, the former preparation is deactivated earlier than the latter one. The activity found in growing cells is not modified after inhibition of protein synthesis by cycloheximide or amino acid starvation or by the inhibition of RNA synthesis. It was possible to activate the chitin synthase ofS. cerevisiae cdc 25 grown at 23°C by means of pronase, whereas trypsin had no effect. After the cells were grown at 37°C, chitin synthase could not be activated either with tryp…
In vivo imaging and quantification of the continuous keratin filament network turnover
2008
Keratin polypeptides are major components of the epithelial cytoskeleton forming a filamentous 3D-network. Like intermediate filament polypeptides of other cell types, keratins make up a stable, but elastic network that is responsible for mechanical stress resilience. At the same time the keratin network is able to change its shape during development, cell division, metastasis and cell migration.