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S Lovtrup

Publications and source records attributed to S Lovtrup.

At least 19 recordsLinked to original sources
PubMed1976

On the determination of the dorso-ventral polarity in the amphibian embryo: suppression by lactate of the formation of Ruffini's flask-cells.

Cells isolated from the vegetal hemisphere of the blastula of Ambystoma mexicanum differentiate spontaneously into fibroblast-like cells. Similar cells may be formed from animal cells, provided they are induced either by vegetal cells or by Li+. We have found that lactate and various inhibitors of RNA synthesis suppress the spontaneous cell differentiation. The effect of lactate differs from that of the other agents in so far as lactate must be present before the second day of culture to suppress the outgrowth of fibroblasts on the third day; the other inhibitors are active also when added on the second day. An explanation of this difference may possibly be found in the fact that lactate suppresses incorporation of RNA but only by 40%. The effect on the differentiation of various substances supposed to interfere with the metabolism of lactate was established. The results obtained were suggestive, but not conclusive. It is concluded that the effect of anaerobiosis may be explained as a lactate inhibition. The amounts of lactate under aerobic conditions are so slight that it is unlikely, but not impossible, that lactate is directly involved in the control of differentiation.

Ambystoma↗
PubMed1975

On the determination of the dorso-ventral polarity in Xenopus laevis embryos.

When embryos, or dorsal or ventral half-embryos, of Xenopus laevis are subjected to unilateral restriction of oxygen supply, the posterior end will always appear at the aerobic side, while the development of the anterior end, oriented towards the anaerobic side, will be partly suppressed. The shorter the time treatment lasts, the more normal the development will be. When the restriction of oxygen effects an inversion of the dorso-ventral polarity, development is retarded, otherwise not. Measurements of oxygen consumption show a substantial reduction in the experimental embryos, as compared with normal ones. The change in oxygen consumption in inverted embryos is delayed relative to non-inverted ones, but there is no significant difference in the total consumption of oxygen. Our results support the idea that the dorso-ventral polarity is associated with a gradient in oxygen consumption, and various kinds of evidence suggest that oxygen consumption is, in part, required for the formation of Ruffini's flask-cells, responsible for the initiation of invagination. It is suggested that the basic mechanisms involved in the determination of the normal, and the inverted, dorso-ventral polarity are fundamentally different, the latter being in fact an induction of a new polarity.

Animals↗