Showing papers on "Transdifferentiation published in 1980"
TL;DR: There are a number of reasons, although they are not absolutely convincing, as to why transdifferentiation can be a regulatory change not mainly due to a selective outgrowth of mutated cells or a small subpopulation of cells programmed toward only lens or pigment cells.
Abstract: Publisher Summary This chapter discusses the possible mechanisms of transdifferentiation or cellular metaplasia as a model for studying the programming of differentiation in neural and other cells at the cellular and molecular levels. Vertebrate eye tissues are characterized by a unique ability to perform extensive tissue metaplasia and to convert their specificities during regeneration in situ, after the removal of particular tissues. Studies on such instability in differentiation have now been extended to the cellular level by means of cell culture experiments. Besides the pigmented epithelial cells of the retina, cells from the neural retina (NR) of a number of vertebrate species can also extensively transdifferentiate into lens and pigment cells under conditions of cell culture. All the literature since 1975, when the phenomenon was first announced, has been reviewed in the chapter. Transdifferentiation in vitro is a sequential process starting from NR cells and terminating with lens cells, either through the differentiation of pigment cells or not. Several intrinsic and external factors affecting transdifferentiation have been described along with the molecular events observed in the process. There are a number of reasons, although they are not absolutely convincing, as to why transdifferentiation can be a regulatory change not mainly due to a selective outgrowth of mutated cells or a small subpopulation of cells programmed toward only lens or pigment cells.
188 citations
TL;DR: Findings suggest a "transdifferentiation" of C6 glial cells with passage in culture, as well as an enzyme marker for oligodendrocytes that is low in the early passages and high in the late passages.
Abstract: The activities of cyclic nucleotide phosphohydrolase, an enzyme marker for oligodendrocytes, and glutamine synthetase, an enzyme marker for astrocytes, were studied at early (21 to 26) and late (82 to 88) cell passages. The activity of cyclic nucleotide phosphohydrolase was markedly high and that of glutamine synthetase was low in the early passages, but this relation was reversed in the late passages. These findings suggest a "transdifferentiation" of C6 glial cells with passage in culture.
176 citations
TL;DR: The results indicate that conditions most favourable to the maintenance of the neuronal specificity in cell cultures of neural retina, can also support the most extensive transdifferentiation.
Abstract: The effects of three different culture media (Eagle's MEM, F-12 and L-15) on the transdifferentiation of 8-day chick embryonic neural retina into lens cells, were examined with respect to the expression of two phenotypes. One type referred to neuronal specificity (as represented by the level of cholineacetyl-transferase, CAT, activity) and the other to lens specificity (as represented by content of α-and δ-crystallin). In 7-day cell cultures before the visible differentiation of lentoid bodies, CAT activity was detected in all media. But, its level was about 9 times higher in cultures with L-15 than in those with MEM and 3 times higher than in F-12. In 26-day cultures, CAT activity was practically undetectable. The production of α-and δ-crystallin was detected in cultures at 26 days. There were quantitative differences in the crystallin content with different media, and it was highest in cultures with L-15. The results indicate that conditions most favourable to the maintenance of the neuronal specificity in cell cultures of neural retina, can also support the most extensive transdifferentiation. The possibility of direct transdifferentiation of once neuronally specified cells into lens cells in cultures with L-15 has been suggested to explain the present results.
9 citations
TL;DR: Mutant chickens, Hy‐1 and Hy‐2, show abnormalities in growth and differentiation of the lens epithelium and neural retinal cells from 3.5‐day‐old embryos of these mutants were cultured, and the differentiation in vitro was compared with the cells of the normal strain.
Abstract: Mutant chickens, Hy-1 and Hy-2, show abnormalities in growth and differentiation of the lens epithelium. In this study, neural retinal cells (NR cells) from 3.5-day-old embryos of these mutants were cultured, and the differentiation in vitro was compared with the cells of the normal strain. Hy-1 cells in vitro were characterized by a delay in the first appearance of neuronal cells (N-cells) and by excessive production of this cell type at later stages. By contrast, the Hy-2 cells were indistinguishable from the normal cells in the early phase of culturing.
In spite of the marked difference of Hy-1 NR cells in neuronal differentiation up to about 7 days in culture, the transdifferentiation of lens and pigmented cells occurred to a similar extent and with the same time schedule as cultures of normal cells. A number of lentoid bodies were formed by about 10 days. The relative composition of the three major classes of crystallins in transdifferentiated lens cells was almost identical between normal and Hy-1 strains. The results were discussed in comparison with the previous results of cell culture of NR of 8-day embryonic mutant chickens, and it was concluded that the process of transdifferentiation in cell culture is different between NR from 3.5-day-old and 8-day-old embryos.
2 citations