[Inhibitory effects of homospecific non-histone chromatin proteins on morphogenesis of urodele amphibian embryos].

Non-histone chromosomal proteins (NHCP) were injected into the blastocoel of advanced blastulae fromPleurodeles waltlii which were previously punctured. NHCP extracted from the liver of the same amphibian species bring very strongly inhibitory effects on morphogenesis: gastrulation is prevented in 75% of cases, but the embryos can survive for 8 to 10 days without showing any necrotic cells, and cell divisions still occur sporadically. Intercellular adhesivity is strongly impaired in such embryos, in connection with inhibition of morphogenetic movements. Gastrulation is delayed and abnormal in other embryos, and neurulation is severely disturbed, the neural tube being unclosed or much reduced in size and the notochord and somites poorly differentiated. In contrast, NHCP extracted from other animal species (rat and chicken liver, rat ascites) have practically no effects onPleurodeles embryos. Species-specific inhibitory effects are thus demonstrated and compared with those which were previously studied on cultures of differentiating embryonic cells fromPleurodeles waltlii andAmbystoma mexicanum. The possible levels at which NHCP act are discussed, the changes in intercellular adhesivity being noted as more conspicuous in the present experiments.