Pinocytosis as an essential transport mechanism of metazoan cells in culture

Inhibition of DNA Synthesis and Mitosis by DNA Affinity Proteins Released from Thymus Cells during in Vitro Incubation

“…from cerebrospinal fluid (14), serum (28), and supernatants of mitogen-activated tonsil cells culture (15), bind DNA , and their functions have been postulated to be similar to those of the nuclear-regulatory nonhistone proteins. Michl and Spurna have shown that culture cells take up a serum alpha-globulin into their nuclei that has been shown to have a strong binding capacity for thymidine and mitogenic activity in metazoan cells (18). The fact that the ss-DNA-binding proteins studied here, were obtained from the culture medium of normal thymus cells, indicates that our proteins differ from those reported in the above studies.…”

“…Animal cells cultured in vitro (nonlymphocytes) also are believed release various macromolecules into the medium which influence cell proliferation and differentiation (9,21,27). These molecules and exogenously added proteins are taken up by other cells ; thus they are means of cell communication (12,13,18,23).…”

Uptake and fate of water-soluble, nondegradable polymers with antiviral activity in cells and animals

“…29 However, the rate of uptake of these polymers is about the same as that of polysaccharides and is much slower than that of polynucleotides.30 The rate of uptake suggests the possibility of pinocytotic entry, which is believed to be of universal occurrence in cells in culture. 31,32 However, considerable amounts of polymer are not encapsulated in vesicles but are found in the soluble fraction of the cytoplasm. In animals, foreign macromolecules are known to enter cells, predominantly of the reticuloendothelial system, by two mechanisms-pinocytosis and phagocytosis.…”

Complete replacement of serum in primary cultures of chick embryo brain cells by growth-promoting alpha-globulin

“…GPAG was prepared by fractionation with ammonium sulphate and purified by repeated precipitation at pH 5. The biochemical and physiological characteristics of GPAG were described in our previous communications5, 8,13. Cerebral hemispheres from 7-day-old chick embryos were mechanically dissociated in phosphatebuffered saline (PBS) and the cell suspension was centrifuged at t70• g for 3 min.…”