Effects of Cytochalasins on the Initial Aggregation in Vitro of Embryonic Chick Cells

1974 ◽  
Vol 14 (1) ◽  
pp. 187-196
Author(s):  
J. C. APPLETON ◽  
R. B. KEMP
Keyword(s):  
Cytochalasin B ◽  
Cell Aggregation ◽  
Cellular Injury ◽  
Cellular Motility ◽  
Carbon Dioxide Evolution ◽  
Site Of Action ◽  
Dissociated Cells ◽  
Cytochalasin A ◽  
Final Confirmation

The initial aggregation of trypsin-dissociated cells from the skeletal muscle tissue of 9-day-old chick embryos in the presence of cytochalasins A and B was studied in order to discover the effects of these agents on contact and adhesion. Cytochalasin B (3 µg/ml) had a negligible effect on the rate of aggregation of cells over an 8-h period, but cytochalasin A at concentrations between 3 and 20 µg/ml markedly inhibited aggregation. Both agents altered the shape and size of aggregates and caused cells at their periphery to appear more spherical. The oxygen uptake of the treated cells was not noticeably different from that of the controls, despite the severe inhibition of isotopic carbon dioxide evolution. The effect of cytochalasin B on cell aggregation was reversible and although the cytochalasin A effect could not be abolished on return to medium free of A, the unaltered oxygen consumption was taken as an indication that permanent cellular injury did not occur. The effect of the cytochalasins on aggregate structure was interpreted on the basis of arrested cellular motility, but the singular inhibition by cytochalasin A of the rate of aggregation must await final confirmation of its site of action.

Evidence for the Importance of Puromycyl Peptides in the Inhibition by Puromycin of Cell Aggregation In Vitro

1973 ◽  
Vol 12 (2) ◽  
pp. 641-653
Author(s):  
M. J. DUNN ◽  
E. OWEN ◽  
R. B. KEMP
Keyword(s):  
Carbon Dioxide ◽  
Protein Synthesis ◽  
Cell Aggregation ◽  
Experimental Period ◽  
Respiratory Metabolism ◽  
Inhibitory Effects ◽  
Carbon Dioxide Evolution ◽  
Dissociated Cells ◽  
Cellular Oxygen

Trypsin-dissociated cells from the muscle tissue of 9-day-old chick embryos were employed to investigate the effects of cycloheximide and a puromycin-cycloheximide mixture on cell aggregation, protein synthesis and respiratory metabolism. Cycloheximide when introduced at a concentration of 10 µg/ml into a suspension of cells in Eagle's MEM inhibited aggregation by 25% at 24 h. At this time an inhibition of 40% was apparent in the presence of a mixture of cycloheximide and puromycin both at a concentration of 10 µg/ml. Both cycloheximide and the cycloheximide-puromycin mixture arrested protein synthesis of rotated cells by 90% within 15 min of introducing the antibiotics into cell suspensions. The antibiotics retained their inhibitory effects on protein synthesis for the 24-h period of rotation. Cycloheximide inhibited cellular oxygen uptake and carbon dioxide evolution of rotated cells by 25% at the end of the 24-h experimental period. At this time an inhibition of 30% was observed in the presence of the cycloheximide-puromycin mixture. The release of radioactive carbon dioxide by cycloheximide-treated cells was inhibited by 46% at 24 h. In the presence of the antibiotic mixture, 14CO2 release was inhibited by 30% at 4 h, but after 8 h very little further 14CO2 was evolved. As a control, puromycin (10 µg/ml) inhibited cell aggregation and respiration to an extent similar to that previously reported. The results are discussed in terms of puromycyl peptides producing a metabolic effect on cell aggregation. It is considered that this is additional to the effect of puromycin inhibiting aggregation through the arrest of protein synthesis.

Abolition by Myosin and Heavy Meromyosin of the Inhibitory Effect of Smooth-Muscle Actomyosin Antibodies on Cell Aggregation In Vitro

1973 ◽  
Vol 12 (2) ◽  
pp. 631-639
Author(s):  
R. B. KEMP ◽  
B. M. JONES ◽  
U. GRÖSCHEL-STEWART
Keyword(s):  
Smooth Muscle ◽  
Striated Muscle ◽  
Cell Aggregation ◽  
Inhibitory Effect ◽  
Regulatory Function ◽  
Rabbit Serum ◽  
Heavy Meromyosin ◽  
Γ Globulins ◽  
Dissociated Cells

The ability of anti-chicken smooth-muscle actomyosin γ-globulins (anti-GAM) to inhibit the aggregation of dissociated cells from the skeletal muscle and liver of chick embryos was abolished by pretreatment of the anti-GAM with either myosin or heavy meromyosin (HMM). When the same cells were treated with HMM at a concentration of 1 mg per 2 x 106 cells/ml Eagle's MEM they aggregated as readily as untreated cells. The negative electrophoretic mobility of the embryonic chick fibroblastic cells was significantly reduced by the globulin fraction of anti-GAM but not of HMM-treated anti-GAM or non-immunized rabbit serum. Anti-chicken striated muscle actomyosin γ-globulins slightly reduced negative mobility but HMM had no effect. The experiments show that the inhibitory effect on cell aggregation of anti-GAM preparations is produced by the anti-myosin antibodies. They also provide support for the theory that a surface-localized myosin-like protein has a regulatory function in cell adhesion.

Studies on the Mechanism Underlying the Inhibition by Puromycin of Cell Aggregation In Vitro

1970 ◽  
Vol 7 (2) ◽  
pp. 557-573
Author(s):  
M. J. DUNN ◽  
E. OWEN ◽  
R. B. KEMP
Keyword(s):  
Carbon Dioxide ◽  
Protein Synthesis ◽  
Cellular Metabolism ◽  
Cell Aggregation ◽  
Experimental Period ◽  
Inhibitory Effect ◽  
Dissociated Cells ◽  
Gyratory Shaker ◽  
Reduced Rate

Cells dissociated with 0.25% crude trypsin from the muscle tissue of 9-day-old chick embryos were employed to investigate the effect of puromycin on cellular metabolism. Parallel studies were also made, using the gyratory shaker, to confirm the effectiveness of puromycin in inhibiting cell aggregation and protein synthesis. Puromycin when introduced at a concentration of 10µg/ml into a suspension of cells in Eagle's MEM did not completely inhibit cell aggregation. Small aggregates were formed in the first 4 h of the experiment. Protein synthesis of the rotated cells, as measured by the incorporation of L-[α-14C]leucine into proteins, was arrested by 91.7% within 15 min of introducing puromycin into a cell suspension. The antibiotic retained its inhibitory effect on protein synthesis for the 24-h period of rotation. Puromycin inhibited the cellular oxygen uptake and carbon dioxide evolution of the rotated cells by 40% within 4 h of its introduction. However, treated cells were still respiring, though at a much reduced rate, at the end of the 24-h experimental period. The release of radioactive carbon dioxide by puromycin-treated cells was also inhibited by 40% at the 4-h stage but after 8 h no further 14CO2 was evolved. The presence of the antibiotic markedly inhibited the uptake of glucose by trypsin-dissociated cells. The level of glycogen and lactate in cells suspended in Eagle's MEM was reduced very considerably over a 24-h period. The presence of puromycin accelerated glycogen utilization over the first 6 h of rotation but at 24 h there was a difference of only 0.6% between the glycogen content of treated cells and controls. At 24 h 11.3% less lactate remained in the puromycin-treated cells than in the controls. The ATP/ADP ratio of trypsin-dissociated cells decreased from an initial value of 2.59 to 1.45 after rotation for 24 h. In the presence of puromycin the ATP/ADP ratio was 0.62 at 4 h and had further declined to 0.48 by 24 h. The effects of puromycin on the aggregation, protein synthesis and cellular metabolism of trypsin-dissociated cells are discussed in relation to cellular adhesive mechanisms.

Reconstruction of Mammalian Heart Tissue from Isolated Embryonic Heart Cells

1977 ◽  
Vol 35 ◽  
pp. 580-581
Author(s):  
Asish C. Nag ◽  
Debra S. Buszke
Keyword(s):  
Basal Medium ◽  
Cell Aggregation ◽  
Heart Tissue ◽  
Cell Suspensions ◽  
Heart Cells ◽  
Mammalian Heart ◽  
Dissociated Cells ◽  
Gyratory Shaker ◽  
And Function

Although monolayer cultures are useful in various cell studies, they are not always adequate for examining the nature of cellular interrelationships and interactions in the formation, differentiation, and function of tissues. The procedures of aggregation in vitro of dissociated cells (Moscona & Moscona, 1966) enable one to study in detail the formation of cell contacts, the assembly of cells into multicellular systems, and cell cooperation in forming organized and differentiating tissues. We adapted the techniques of cell aggregation by rotation to studies on embryonic mammalian heart cells. Cell suspensions from the 18-day-old embryonic rat were prepared by dissociation with 0. 5% trypsin. The cells were dispersed in a culture medium which consisted of Eagle's basal medium with 10% fetal bovine serum, 1% glutamine solution, and 1% penicillin-streptomycin mixture. Cultured in 25ml Erlenmeyer flasks on a gyratory shaker at 70 rpm at 37°C were 3ml aliquots of the cell suspensions.

THYROID STIMULATORS AND THYROID STIMULATION

1971 ◽  
Vol 66 (3) ◽  
pp. 558-576 ◽  
Author(s):  
Gerald Burke
Keyword(s):  
Regulatory System ◽  
Control Site ◽  
Thyroid Cell ◽  
Primary Control ◽  
Physico Chemical ◽  
Site Of Action ◽  
Long Acting

ABSTRACT A long-acting thyroid stimulator (LATS), distinct from pituitary thyrotrophin (TSH), is found in the serum of some patients with Graves' disease. Despite the marked physico-chemical and immunologic differences between the two stimulators, both in vivo and in vitro studies indicate that LATS and TSH act on the same thyroidal site(s) and that such stimulation does not require penetration of the thyroid cell. Although resorption of colloid and secretion of thyroid hormone are early responses to both TSH and LATS, available evidence reveals no basic metabolic pathway which must be activated by these hormones in order for iodination reactions to occur. Cyclic 3′, 5′-AMP appears to mediate TSH and LATS effects on iodination reactions but the role of this compound in activating thyroidal intermediary metabolism is less clear. Based on the evidence reviewed herein, it is suggested that the primary site of action of thyroid stimulators is at the cell membrane and that beyond the(se) primary control site(s), there exists a multifaceted regulatory system for thyroid hormonogenesis and cell growth.

scholarly journals Testing Strategies of the In Vitro Micronucleus Assay for the Genotoxicity Assessment of Nanomaterials in BEAS-2B Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1929
Author(s):  
Tereza Cervena ◽  
Andrea Rossnerova ◽  
Tana Zavodna ◽  
Jitka Sikorova ◽  
Kristyna Vrbova ◽  
...  
Keyword(s):  
Cytochalasin B ◽  
Culture Media ◽  
Methodological Approach ◽  
Micronucleus Assay ◽  
Toxicity Testing ◽  
In Vitro Toxicity ◽  
Testing Strategies ◽  
Transmission Electron ◽  
The Impact

The evaluation of the frequency of micronuclei (MN) is a broadly utilised approach in in vitro toxicity testing. Nevertheless, the specific properties of nanomaterials (NMs) give rise to concerns regarding the optimal methodological variants of the MN assay. In bronchial epithelial cells (BEAS-2B), we tested the genotoxicity of five types of NMs (TiO2: NM101, NM103; SiO2: NM200; Ag: NM300K, NM302) using four variants of MN protocols, differing in the time of exposure and the application of cytochalasin-B combined with the simultaneous and delayed co-treatment with NMs. Using transmission electron microscopy, we evaluated the impact of cytochalasin-B on the transport of NMs into the cells. To assess the behaviour of NMs in a culture media for individual testing conditions, we used dynamic light scattering measurement. The presence of NMs in the cells, their intracellular aggregation and dispersion properties were comparable when tests with or without cytochalasin-B were performed. The genotoxic potential of various TiO2 and Ag particles differed (NM101 < NM103 and NM302 < NM300K, respectively). The application of cytochalasin-B tended to increase the percentage of aberrant cells. In conclusion, the comparison of the testing strategies revealed that the level of DNA damage induced by NMs is affected by the selected methodological approach. This fact should be considered in the interpretation of the results of genotoxicity tests.

PLATELET ACTIVATION BY HUMAN CANCER CELLS GROWN “IN VITRO” OR DISSOCIATED FROM TUMOUR TISSUES

1987 ◽  
Author(s):  
G Grignani ◽  
L Pacchiarini ◽  
M Zucchella ◽  
L Dezza ◽  
S C Rizzo
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Human Cancer ◽  
Iodoacetic Acid ◽  
Tumour Cells ◽  
Human Cancer Cells ◽  
Human Tumour Cells ◽  
Dissociated Cells ◽  
Lymphoblastic Cells

The mechanisms of platelet activation by human tumour cells grown “in vitro” or freshly dissociated from tumour tissues have been investigated.MoCCL human T-lymphoblastic cells cultured “in vitro” induced platelet aggregation through the production of ADP, as evidenced by inhibition of the effect by apyrase. The maximum of ADP production by tumour cells was reached after 1 hour and was 225 p moles/106 cells.On the contrary, platelet aggregation induced by 5637 human bladder carcinoma cells was not inhibited by apyrase, but was abolished by hirudin, indicating the important role of thrombin in this effect.Tumour cells dissociated from 3 breast carcinomas showed a very high platelet aggregating activity, which was not inhibited by hirudin or apyrase, but was abolished by iodoacetic acid, suggesting a role for a cystein-protease in platelet activation.These results confirm that platelets can be activated by tumour cells through different mechanisms; they also suggest that the methods employed to obtain the tumour cells can influence the results, probably because of the different cell populations which are present in the dissociated tumour tissues.Informations obtained with freshly dissociated cells are interesting, because this method has been used seldom so far and because it provides a more physiological approach to the study of the interactions of tumours and platelets.

Dynamics of cell aggregation during in vitro neurogenesis by immortalized neuroectodermal progenitors

2000 ◽  
Vol 60 (2) ◽  
pp. 184-194 ◽  
Author(s):  
Katalin Schlett ◽  
Andr�s Czir�k ◽  
Kriszti�n T�rnok ◽  
Tam�s Vicsek ◽  
Em�lia Madar�sz
Keyword(s):  
Cell Aggregation
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