Rotavirus Persistence in Cell Cultures: Selection of Resistant Cells in the Presence of Foetal Calf Serum

AbstractWe report the development of a lab-on-a-chip system, that facilitates coupled dielectrophoretic detection (DEP-D) and impedimetric counting (IM-C), for investigating drug resistance in K562 and CCRF-CEM leukemia cells without (immuno) labeling. Two IM-C units were placed upstream and downstream of the DEP-D unit for enumeration, respectively, before and after the cells were treated in DEP-D unit, where the difference in cell count gave the total number of trapped cells based on their DEP characteristics. Conductivity of the running buffer was matched the conductivity of cytoplasm of wild type K562 and CCRF-CEM cells. Results showed that DEP responses of drug resistant and wild type K562 cells were statistically discriminative (at p = 0.05 level) at 200 mS/m buffer conductivity and at 8.6 MHz working frequency of DEP-D unit. For CCRF-CEM cells, conductivity and frequency values were 160 mS/m and 6.2 MHz, respectively. Our approach enabled discrimination of resistant cells in a group by setting up a threshold provided by the conductivity of running buffer. Subsequent selection of drug resistant cells can be applied to investigate variations in gene expressions and occurrence of mutations related to drug resistance.

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Fetal calf serum contains activities that induce fetal hemoglobin in adult erythroid cell cultures

Blood ◽

10.1182/blood.v75.9.1862.1862 ◽

1990 ◽

Vol 75 (9) ◽

pp. 1862-1869 ◽

Cited By ~ 13

Author(s):

P Constantoulakis ◽

B Nakamoto ◽

T Papayannopoulou ◽

G Stamatoyannopoulos

Keyword(s):

Cell Cultures ◽

Fetal Calf Serum ◽

Calf Serum ◽

Fetal Hemoglobin ◽

Erythroid Cell ◽

Erythroid Progenitors ◽

Globin Mrna ◽

Erythroid Progenitor ◽

Fetal Sheep ◽

Gamma Globin

Abstract Cultures of peripheral blood or bone marrow erythroid progenitors display stimulated production of fetal hemoglobin. We investigated whether this stimulation is due to factors contained in the sera of the culture medium. Comparisons of gamma/gamma + beta biosynthetic ratios in erythroid colonies grown in fetal calf serum (FCS) or in charcoal treated FCS (C-FCS) showed that FCS-grown cells had significantly higher gamma/gamma + beta ratios. This increase in globin chain biosynthesis was reflected by an increase in relative amounts of steady- state gamma-globin mRNA. In contrast to its effect on adult cells, FCS failed to influence gamma-chain synthesis in fetal burst forming units- erythroid (BFU-E) colonies. There was a high correlation of gamma- globin expression in paired cultures done with C-FCS or fetal sheep serum. Dose-response experiments showed that the induction of gamma- globin expression is dependent on the concentration of FCS. These results indicate that FCS contains an activity that induces gamma- globin expression in adult erythroid progenitor cell cultures.

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The role of calcium in the increase in flocculence of yeast growing in the presence of copper

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1965.0056 ◽

1965 ◽

Vol 162 (989) ◽

pp. 555-566 ◽

Cited By ~ 2

Keyword(s):

Liquid Medium ◽

Cell Cultures ◽

Chloride Solution ◽

Liquid Copper ◽

Acquired Resistance ◽

Calcium Chloride Solution ◽

Copper Resistance ◽

Liquid Cultures ◽

Selection Of

Growth in the presence of inhibitory concentrations of copper enhances the tendency of yeast to flocculate. Many yeasts will not flocculate unless calcium is included in the growth medium and Guinness strain 522 used in the present work required a relatively large amount. Single cell cultures may undergo variation during subculture, resulting in the production of a large number of variants (Chester 1963). The cells of these variants differ considerably in their ability to adhere together. Flocculation variants of strain 522 differed among themselves in the amount of calcium necessary for flocculation, the most flocculent variants requiring least calcium. Washed cells of the more flocculent yeasts removed more calcium from a calcium chloride solution than did those with lesser powers of adhesion. In a copper medium containing calcium the more flocculent variants replaced the less flocculent. Calcium protected cells from copper and the more flocculent variants enjoyed most protection. All variants acquired resistance to copper during growth in the copper medium. Despite the selection of the more flocculent yeasts during growth in liquid medium, their copper resistance was less than that of the less flocculent yeasts. When calcium was added to the liquid copper medium, cultures developed less resistance. It is concluded that the less flocculent cells, having less protection by calcium, were exposed to what was effectively a greater concentration of copper and therefore became more resistant. This greater resistance did not enable these cells to compete with the flocculent cells in liquid cultures.

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