Article révisé par les pairs
Résumé : Both the oxidized and the reduced forms of lipoic acid inhibit neural tube closure in pleurodeles and in chicken embryos. Oxidized lipoic acid inhibits the incorporation of H3-uridine and H3-cytidine into DNA; it inhibits the stage which involves the reduction of the ribonucleosides to the deoxyribonucleosides: in fact, the incorporation of H3-deoxyuridine is little or not at all affected by this substance. The action of reduced lipoic acid and reduced triphosphopyridine nucleotide on the reduction of ribose to deoxyribose is just the opposite of that exerted by oxidized lipoic acid. The addition of TPNH to oxidized lipoic acid prevents the inhibition of the incorporation of the ribonucleosides normally observed with oxidized lipoic acid. The degree of incorporation of H3-thymidine in the presence of these components appears to be "complementary" to the incorporation of H3-uridine and H3-cytidine into DNA. RNA metabolism is also deeply disturbed in embryos treated with oxidized or reduced lipoic acid. The effect of lipoic acid, whether oxidized or reduced, seems to be specific, since neither dithiodiglycol nor mercaptoethanol have the same effects on the incorporation of ribonucleosides into DNA. The significance of these autoradiographic findings is discussed; it is finally suggested that the arrest of morphogenesis might result from a disturbance of nucleic acid metabolism. © 1964.