scholarly journals Dihydrocytochalasin B. Biological effects and binding to 3T3 cells.

1978 ◽  
Vol 76 (2) ◽  
pp. 360-370 ◽  
Author(s):  
S J Atlas ◽  
S Lin
Keyword(s):  
Cell Motility ◽  
Morphological Changes ◽  
Biological Effects ◽  
Sugar Transport ◽  
Sugar Uptake ◽  
3T3 Cells ◽  
Binding Studies ◽  
High Affinity ◽  
Undetermined Function ◽  
Induced Changes

Dihydrocytochalasin B (H2CB) does not inhibit sugar uptake in BALB/c 3T3 cells. Excess H2CB does not affect inhibition of sugar uptake by cytochalasin B (CB), indicating that it does not compete with CB for binding to high-affinity sites. As in the case of CB, H2CB inhibits cytokinesis and changes the morphology of the cells. These results demonstrate that the effects of CB on sugar transport and on cell motility and morphology involve separate and independent sites. Comparison of the effects of H2CB, CB, and cytochalasin D (CD) indicates that treatment of cells with any one of the compounds results in the same series of morphological changes; the cells undergo zeiosis and elongation at 2-4 microM CB and become arborized and rounded up at 10-50 microM CB. H2CB is slightly less potent than CB, whereas CD is five to eight times more potent than CB in causing a given state of morphological change. These results indicate that the cytochalasin-induced changes in cell morphology are mediated by a specific site(s) which can distinguish the subtle differences in the structures of the three compounds. Competitive binding studies indicate that excess H2CB displaces essentially all of the high-affinity bound [3H]CB, but, at less than 5 x 10(-5) M H2CB is not so efficient as unlabeled CB in the displacement reaction. In contrast, excess CD displaces up to 40% of the bound [3H]CB. These results suggest that three different classes of high-affinity CB binding sites exist in 3T3 cells: sites related to sugar transport, sites related to cell motility and morphology, and sites with undetermined function.

scholarly journals The Hexose-Proton Cotransport System of Chlorella

1974 ◽  
Vol 64 (5) ◽  
pp. 568-581 ◽  
Author(s):  
Ewald Komor ◽  
Widmar Tanner
Keyword(s):  
Sugar Transport ◽  
Protonated Form ◽  
Weak Acid ◽  
Sugar Uptake ◽  
Sugar Accumulation ◽  
Maximal Velocity ◽  
Uptake System ◽  
High Affinity ◽  
Ph Values ◽  
Proton Concentration

The proton concentration in the medium affects the maximal velocity of sugar uptake with a Km of 0.3 mM (high affinity uptake). By decreasing the proton concentration a decrease in high affinity sugar uptake is observed, in parallel the activity of a low affinity uptake system (Km of 50 mM) rises. Both systems add up to 100%. The existence of the carrier in two conformational states (protonated and unprotonated) has been proposed therefore, the protonated form with high affinity to 6-deoxyglucose, the unprotonated form with low affinity. A plot of extrapolated Vmax values at low substrate concentration versus proton concentration results in a Km for protons of 0.14 µM, i.e. half-maximal protonation of the carrier is achieved at pH 6.85. The stoichiometry of protons cotransported per 6-deoxyglucose is close to 1 at pH 6.0–6.5. At higher pH values the stoichiometry continuously decreases; at pH 8.0 only one proton is cotransported per four molecules of sugar. Whereas the translocation of the protonated carrier is strictly dependent on sugar this coupling is less strict for the unprotonated form. Therefore at alkaline pH a considerable net efflux of accumulated sugar can occur. The dependence of sugar accumulation on pH has been measured. The decrease in accumulation with higher pH values can quantitatively be explained by the decrease in the amount of protonated carrier. The properties of the unprotonated carrier resemble strikingly the properties of carrier at the inner side of the membrane. The inside pH of Chlorella was measured with the weak acid 5,5-dimethyl-2, 4-oxazolidinedion (DMO). At an outside pH of 6.5 the internal pH was found to be 7.2. To explain the extent of sugar accumulation it has to be assumed that the membrane potential also contributes to active sugar transport in this alga.

Lectin Binding Studies on RNA Tumor Virus-Infected Cells

1975 ◽  
Vol 33 ◽  
pp. 326-327
Author(s):  
D. C. Hixson
Keyword(s):  
Binding Sites ◽  
Lectin Binding ◽  
Culture Conditions ◽  
3T3 Cells ◽  
Binding Studies ◽  
Con A ◽  
Microscopic Studies ◽  
Tumor Virus ◽  
Infected Cells ◽  
Cell Culture Conditions

The abilities of plant lectins to preferentially agglutinate malignant cells and to bind to specific monosaccharide or oligosaccharide sequences of glycoproteins and glycolipids make them a new and important biochemical probe for investigating alterations in plasma membrane structure which may result from malignant transformation. Electron and light microscopic studies have demonstrated clustered binding sites on surfaces of SV40-infected or tryp- sinized 3T3 cells when labeled with concanavalin A (con A). No clustering of con A binding sites was observed in normal 3T3 cells. It has been proposed that topological rearrangement of lectin binding sites into clusters enables con A to agglutinate SV40-infected or trypsinized 3T3 cells (1). However, observations by other investigators have not been consistent with this proposal (2) perhaps due to differences in reagents used, cell culture conditions, or labeling techniques. The present work was undertaken to study the lectin binding properties of normal and RNA tumor virus-infected cells and their associated viruses using lectins and ferritin-conjugated lectins of five different specificities.

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

scholarly journals Biological effects of tourmaline treatment on Dehalococcoides spp. during the reductive dechlorination of trichloroethylene

RSC Advances ◽  
2021 ◽  
Vol 11 (20) ◽  
pp. 12086-12094
Author(s):  
Tielong Li ◽  
Jiaxin Wen ◽  
Bingjie Li ◽  
Shihu Ding ◽  
Wei Wang
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Community Structure ◽  
Reductive Dechlorination ◽  
Biological Effects ◽  
Dechlorinating Bacteria ◽  
Contaminated Aquifers ◽  
Tce Degradation ◽  
Induced Changes

To explore the application of mineral in bioremediation of contaminated aquifers, this study investigated tourmaline-induced changes in TCE degradation, community structure, cell proliferation and gene expression of dechlorinating bacteria.

Effect of training on insulin binding to rat skeletal muscle sarcolemmal vesicles

1986 ◽  
Vol 250 (5) ◽  
pp. E570-E575
Author(s):  
G. K. Grimditch ◽  
R. J. Barnard ◽  
S. A. Kaplan ◽  
E. Sternlicht
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Exercise Training ◽  
Insulin Binding ◽  
Whole Body ◽  
Rat Skeletal Muscle ◽  
Binding Studies ◽  
Muscle Enzyme ◽  
Intravenous Glucose ◽  
High Affinity

We examined the hypothesis that the exercise training-induced increase in skeletal muscle insulin sensitivity is mediated by adaptations in insulin binding to sarcolemmal (SL) insulin receptors. Insulin binding studies were performed on rat skeletal muscle SL isolated from control and trained rats. No significant differences were noted between groups in body weight or fat. An intravenous glucose tolerance test showed an increase in whole-body insulin sensitivity with training, and specific D-glucose transport studies on isolated SL vesicles indicated that this was due in part to adaptations in skeletal muscle. Enzyme marker analyses revealed no differences in yield, purity, or contamination of SL membranes between the two groups. Scatchard analyses indicated no significant differences in the number of insulin binding sites per milligram SL protein on the high-affinity (15.0 +/- 4.1 vs. 18.1 +/- 6.4 X 10(9)) or on the low-affinity portions (925 +/- 80 vs. 884 +/- 106 X 10(9)) of the curves. The association constants of the high-affinity (0.764 +/- 0.154 vs. 0.685 +/- 0.264 X 10(9) M-1) and of the low affinity sites (0.0096 +/- 0.0012 vs. 0.0102 +/- 0.0012 X 10(9) M-1) also were similar. These results do not support the hypothesis that the increased sensitivity to insulin after exercise training is due to changes in SL insulin receptor binding.

scholarly journals Mediation of interleukin-11-dependent biological responses by a soluble form of the interleukin-11 receptor

1996 ◽  
Vol 318 (2) ◽  
pp. 489-495 ◽  
Author(s):  
Julia KAROW ◽  
Keith R. HUDSON ◽  
Mark A. HALL ◽  
Ann B. VERNALLIS ◽  
Jacky A. TAYLOR ◽  
...  
Keyword(s):  
Biological Effects ◽  
Biological Response ◽  
Cytoplasmic Domain ◽  
Soluble Form ◽  
High Affinity ◽  
Biological Responses ◽  
Interleukin 11 ◽  
Biological Actions ◽  
In Cells

Interleukin-11 (IL-11) is a polyfunctional cytokine whose biological actions require a specific IL-11 receptor (IL-11R) and the transmembrane transducer gp130. Here we report the production of a soluble form of the murine IL-11R and demonstrate that it interacts with IL-11 ligand with high affinity. The affinity of IL-11 alone for gp130 is below the level of detection, but a complex of IL-11 and soluble IL-11R interacts with gp130 with high affinity. The addition of soluble IL-11R potentiates the effects of exogenous IL-11 in cells that are normally responsive to IL-11. A biological response to IL-11 can be reconstituted in BAF cells transfected with gp130 by addition of IL-11 and soluble IL-11R. These findings show that the cytoplasmic domain of the IL-11R is not required for the biological effects of IL-11 and that a complex of IL-11 and IL-11R mediates signalling by association with gp130.

Microinjection of smg/rap1/Krev-1 p21 into Swiss 3T3 cells induces DNA synthesis and morphological changes

1992 ◽  
Vol 12 (8) ◽  
pp. 3407-3414
Author(s):  
Y Yoshida ◽  
M Kawata ◽  
Y Miura ◽  
T Musha ◽  
T Sasaki ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Laser Scanning ◽  
Morphological Changes ◽  
Stress Fibers ◽  
Confocal Laser ◽  
3T3 Cells ◽  
Membrane Ruffling ◽  
Ras P21 ◽  
Swiss 3T3 ◽  
Gamma S

Microinjection of either Ki-rasVal-12 p21 or the GDP-bound form of Ki-ras p21 plus smg GDP dissociation stimulator (GDS), a stimulatory GDP/GTP exchange protein for Ki-ras p21, smg/rap1/Krev-1 p21, and rho p21, into quiescent Swiss 3T3 cells induced DNA synthesis irrespective of the presence or absence of insulin. The guanosine 5'-(3-O-thio)triphosphate (GTP gamma S)-bound form of smg p21B or the GDP-bound form of smg p21B plus smg GDS also induced DNA synthesis but only in the presence of insulin. Either the GDP-bound form of Ki-ras p21 or the same form of smg p21B alone was inactive, but smg GDS alone was slightly active only in the presence of insulin. The morphology of the cells was analyzed by scanning electron, phase-contrast, and confocal laser scanning microscopies. Ki-rasVal-12 p21 induced membrane ruffling irrespective of the presence or absence of insulin. The GTP gamma S-bound form of smg p21B showed the same effect only in the presence of insulin. Either the GDP-bound form of Ki-ras p21, the same form of smg p21B, or smg GDS alone was inactive. Upon microinjection of Ki-rasVal-12 p21, stress fibers markedly decreased and the cells became round and piled up. In contrast, upon microinjection of the GTP gamma S-bound form of smg p21B, stress fibers did not markedly decrease and the cells neither became round nor piled up. These results indicate that both ras p21 and smg p21 are mitogenic in Swiss 3T3 cells but that their actions are slightly different.

Modulation of alpha-actinin levels affects cell motility and confers tumorigenicity on 3T3 cells

1994 ◽  
Vol 107 (7) ◽  
pp. 1773-1782 ◽  
Author(s):  
U. Gluck ◽  
A. Ben-Ze'ev
Keyword(s):  
Cell Motility ◽  
Colloidal Gold ◽  
Actin Filaments ◽  
Cell Types ◽  
Cell Behavior ◽  
Regulatory Pathway ◽  
3T3 Cells ◽  
Quiescent Cells ◽  
Beta 1 Integrin ◽  
Cdna Construct

alpha-Actinin is an abundant actin crosslinking protein, also localized at adherens type junctions. In adhesion plaques, alpha-actinin can link the actin filaments to integrin via vinculin and talin, or directly by binding to the cytoplasmic domain of beta 1-integrin. The expression of alpha-actinin is rapidly elevated in growth-activated quiescent cells, and is reduced in SV40-transformed 3T3 cells and various differentiating cell types (reviewed by Gluck, U., Kwiatkowski, D. J. and Ben-Ze'ev, A. Proc. Nat. Acad. Sci. USA 90, 383–387, 1993). To study the effect of changes in alpha-actinin levels on cell behavior, alpha-actinin expression was elevated in 3T3 cells by transfection with a full-length human nonmuscle alpha-actinin cDNA. To suppress alpha-actinin levels, 3T3 cells were transfected with an antisense alpha-actinin cDNA construct. Cells overexpressing alpha-actinin by 40–60% displayed a significant reduction in cell motility, as demonstrated by their slower locomotion into an artificial wound, and by forming shorter phagokinetic tracks on colloidal gold-coated substrata. 3T3 cells in which the expression of alpha-actinin was reduced to 25–60% of control levels, after antisense alpha-actinin transfection, had an increased cell motility. Moreover, such alpha-actinin-deficient 3T3 cells formed tumors upon injection into nude mice. The results demonstrate that modulations in alpha-actinin expression can affect, in a major way, the motile and tumorigenic properties of cells, and support the view that decreased alpha-actinin expression could be a common regulatory pathway to malignant transformation of 3T3 cells.

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