The effect of CuSO4 on the growth of mammalian cell cultures

Alkalinization stimulates Ca2+-dependent spreading during the activation of resting lens epithelial cells in primary culture

Lens epithelium, when attached to its natural substratum, the lens capsule, can be maintained in culture for more than 2 weeks in a simple HEPES- and EDTA-buffered salt solution (HBS). In HBS, the epithelium shows the same characteristic phenomena of locomotion, initial retraction and respreading which in MEM plus serum precedes the inception of DNA synthesis. These phenomena have been shown to be dependent on extracellular Ca2+. 0.05 mM Ca2+ is necessary for maintaining cell-to-cell contacts of the in vivo epithelium. Higher concentrations of Ca2+ cause the epithelium to retract initially. In contrast, Mg2+ greatly favours cell-substratum interactions leading to the formation of lamellopodia and an initial spreading of the epithelium. After some hours in culture the epithelium changes markedly in response to extracellular Ca2+ and Mg2+; it respreads and flattens in the presence of Ca2+, while Mg2+ becomes less effective in maintaining cell-to-substratum contacts. Mg2+-dependent initial spreading is promoted at pH values near 7.0 but the Ca2+-dependent respreading requires an alkalinization of the salt solution.

Trace metal levels in commercially prepared tissue culture media

Four trace elements, lead, copper, tin and zinc, in addition to certain electrolytes, were measured in 11 commercially prepared tissue culture media. Glass media bottles and plastic tissue culture dishes and flasks were treated with a HCl acid solution to determine the amounts of trace metals leached from their surfaces. Zinc, lead and copper were detected in all media. Tin was detected only in RPMI Medium 1640, fetal bovine serum, minimum essential medium and penicillin-streptomycin. It is possible that a major cause of variability in tissue culture experimental results may be due to effects on growth caused by fluctuation in trace element contamination from batch to batch. Variability in establishing primary cultures of corneal endothelial cells was traced to high lead levels in commercially prepared tissue culture media. A strong case is made for continued diligent efforts to expand analytical horizons and our definition of substances in culture media.

The enhancing effect of copper, nickel, and cobalt ions on plaque formation by Semliki Forest virus (SFV) in chicken embryo fibroblasts

In cultured chicken embryo fibroblasts treated with copper-(copper cation 10-minus 3.5-10-minus 5 M), nickel and cobalt salts an enhancement of the plating efficiency of Semliki Forest virus could be observed. This augmented plaque formation was most probably due to a higher adsorption rate of virions to the cell surface under the influence of the transition metal ions. The plating efficiency of West Nile virus in chicken-embryo fibroblasts and, to a lesser degree, of poliovius type 1 and 2 in KB-cells was also enhanced by copper sulfate.

Enhancement of Sendai virus-mediated cell fusion by cupric ions

The effect of divalent cations on cell fusion by concentrated Sendai virus, inactivated by beta-propiolactone, was investigated using Vero and mouse L-929 cells in monolayers. With both cell lines, which are normally resistant to exogenous viral fusion, Cu(2+) in sublethal concentrations was found to promote polykaryon formation to a marked degree. The simultaneous presence of Cu(2+) and virus was required for this effect, which was thought to be related to the cytotoxic action of Cu(2+) on the cell membrane. Accordingly, under standard conditions and in the absence of virus, leakage of isotopically labeled intracellular protein was shown to bear a quantitative relationship to Cu(2+) concentration. Concomitant changes in the membrane were seen electron microscopically to consist of loss of microvilli and the appearance of numerous vesicles on, or adjacent to, the membrane. The relationship of enhanced fusibility to these toxic changes was not further elucidated. The fusion-promoting effect of Cu(2+) far exceeded that of Ca(2+); and other cations tested had no effect.