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G Calothy

Publications and source records attributed to G Calothy.

86 records · Page 5Linked to original sources
PubMed1977

Differentiation of chick embryo neuroretina cells in monolayer cultures. An ultrastructural study. I. Seven-day retina.

Neuroretinas from 6--7 day-old chick embryos were cultivated after trypsin dissociation as monolayer cultures in Petri dishes, and examined after various intervals of time with the electron microscope. Soon after plating, cells begin to reaggregate in small clumps, and typical rosettes are formed. During the first week in vitro, cells appear to differentiate as neuroblasts and presumed Müller cells; the latter form a continous sheet on the substrate, upon which neuroblasts migrate and grow their neurites. Differentiated ribbon synapses are found after 8 days in vitro, the time at which they normally appear in situ. After 15 and 21 days in vitro, synapses are still found in large numbers, mimicking their "in vivo" counterparts. Photoreceptor cells were identified on the basis of the presence of typical ribbons in their cytoplasm, but no outer segment was found. It appears then that synaptogenesis in the retina is programmed independently of the tissue environment, which is markedly disturbed in the monolayer culture.

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PubMed1973

Effect of environmental pH on rescue of Simian virus 40.

Rescue of SV40 virus after Sendai virus-mediated fusion of transformed mouse or hamster cell lines with permissive monkey cells was strikingly dependent on pH in the range 6.4-8.8, with a maximum at pH 8.4. The titer of virus recovered at pH 8.4 was 2 logs higher than that at pH 7.6, and 4 logs higher than that at pH 6.4. The pH-sensitive step was neither the number of heterokaryocytes formed, which was essentially the same at pH 7.6 and 8.4, nor the degree of SV40 replication in the monkey cells, which was also unaffected by pH variation in the range 7.2-8.4.

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PubMedDate not supplied

Induction of proliferation or transformation of neuroretina cells by the mil and myc viral oncogenes.

The genome of the avian retrovirus MH2 contains, in addition to the v-myc oncogene shared with three other avian retroviruses (MC29, CMII and OK-10), a second cell-derived oncogene, v-mil (refs 1-3). Like the three other viruses, which contain only v-myc, MH2 induces mainly liver and kidney carcinomas in fowl and transforms fibroblasts and macrophages in vitro. However, MH2 and MC29 differ in their biological properties when assayed on cultures of chicken embryo neuroretina (NR) cells. Indeed, NR cells, which normally do not multiply in vitro, are induced to proliferate and become transformed upon infection with MH2, whereas infection with MC29 has no apparent effect on these cells. To analyse the functions of the two oncogenes of MH2, we isolated spontaneous and in vitro-constructed mutants of this virus and investigated their effects on NR cell multiplication and transformation. We report here that expression of v-mil is sufficient to induce NR cell proliferation, although it does not result in cell transformation. In addition, viruses expressing only the v-myc oncogene fail to induce any detectable change in NR cells. However, cooperation of the two oncogenes is required to achieve transformation of NR cells by MH2.

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