DNA repair in lens cells during chick embryo development.

When chick lens epithelium is cultured in vitro, differentiation into lens fiber cells is accompanied by DNA degradation. This phenomenom of terminal differentiation was studied in the epithelium from embryos at the 6th and 11th days of development. DNA size and the ability of the cells to repair DNA damage induced by X-rays were analysed in alkaline sucrose gradients.

The repair of DNA single strand breaks in human cells with genetical disorders.

The aim of this work was to make a preliminary examination of some hereditary diseases, related to precocious aging in order to determine whether the defects involved resulted from an impairment of the DNA repair capacity. To test for an impairment in DNA single strand capacity, in cells from patients with different diseases, we have followed the rate of the DNA after X-irradiation by sedimentation on alkaline sucrose gradients. It was found that all cells observed from Lesh Nyhan, cystic fibrosis, trisomy 15 et 21, retinoblastoma, were able to repair the single strand breaks in their DNA to the same extent and at the same initial rate.

Spontaneous transformation of bovine lens epithelial cells: kinetic analysis and differentiation in monolayers and in nude mice.

Bovine lens epithelial cells, in vivo, are known to perform two determined functions. First, they synthesize the lens capsule and subsequently, in the germinal region, they differentiate in fiber cells with massive production of crystallin proteins, inactivation and pyknosis of the nucleus. Bovine lens epithelial cells from adult origin can be cultured but so far no massive crystallin production has been demonstrated in vitro.

Action of ultrasonic irradiation on the DNA of cultivated bovine epithelial lens cell.

Cultivated epithelial lens cells have been submitted to a 20 kHz continuous ultrasonic irradiation. At relativity high intensity, destruction of the cells was observed. At lower intensities, where no cell destruction appeared, the molecular weight of the single strand DNA of these cells was monitored to determine whether breakage of DNA molecules was induced by the ultrasound.

Surface labelling of senescent chick fibroblasts by lactoperoxidase-catalysed iodination.

Cell surface of chick fibroblasts were labelled by a short treatment with 125I in presence of lactoperoxidase. A glycoprotein (220,000 molec. wt) was iodinated and was present in a more exposed position or in greater amounts at the surface of old phase III cells compared to young phase II cells.

Age dependence of the biosynthesis of intercellular matrix macromolecules of rabbit aorta in organ culture and cell culture.

The age dependence of the relative rate of biosynthesis of intercellular matrix macromolecules was studied in organ culture and cell culture obtained from aortas of newborn, young and adult rabbits. In organ culture there was a strong decrease with age of the rate of incorporation of (14C)-lysine and (3H)-glucosamine in all macromolecular fractions. Neosynthesis of elastin could be demonstrated by the isolation of labelled demosine at all ages.

Phosphorylation and protein kinase activities of chromosomal non histone proteins from chick embryo fibroblasts.

Confluent chick embryo fibroblasts were cultured in vitro in (i) medium which prevented the cells from dividing, (ii) medium which stimulated the cells to divide synchronously, (iii) medium without lysine in which the cells were blocked in G1. Chromosomal non histone proteins (NHP) were extracted from cells pulse labelled with 32P phosphate, and the radioactivity analyzed by acrylamide gel electrophoresis. Several radioactive peaks were found all along the gel in the NHP from confluent and stimulated cells.

Lens glycoproteins: biosynthesis in cultured epithelial cells of bovine lens.

1. Radioactivity from [3H]glucosamine is rapidly incorporated into cellular fractions of lens epithelial cells cultured in vitro. The incorporated isotope appears largely in glycoproteins of the cell surface that are exposed to trypsin and are released into a soluble form by proteolysis of intact cells.

[Biosynthesis of macromolecules of the intercellular matrix in aorta organ culture. Influence of the age of the animal].

Rabbit aorta organ cultures were used as a model for the study of the modifications of the rate of biosynthesis of intercellular matrix macromolecules with age. Aortas of new born (100 g), young (400 g) and adult (2 kg) rabbits were maintained in culture for several weeks. 14C-lysine is incorporated in all the macromolecular fractions of the aortas, even in polymeric elastin.

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The interaction of Actinomycin C(1) (AM) with purine nucleosides was investigated by circular dichroism. While dG and dGMP show identical interactions, rG, rGMP and 8-aza-GMP show lower tendency for complex formation. ara-G shows no complex formation.