Volume 3, Issue 4 pp. 389-397
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Effect of actinomycin D on early axial development in chick embryos

Rochelle M. Wolkowski

Rochelle M. Wolkowski

Department of Animal Genetics, University of Connecticut, Storrs, Connecticut 06268

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First published: November 1970
Citations: 2

Scientific contribution no. 413 of the Agricultural Experiment Station, University of Connecticut. Contribution no. 185 of the Institute of Cellular Biology. Supported in part by Fellowship GM-33,242 from the National Institute of General Medical Sciences, Public Health Service and by grant GB 4714 from the National Science Foundation (administered by L. J. Pierro).

Abstract

A study was made of the uptake of actinomycin D, 3H-thymidine, and 3H-uridine in the axial regions of 11- to 13-somite chick embryos cultured in vitro. Actinomycin D was taken up into all regions of embryos, with significantly more actinomycin D per cell in the axial region, including the node and unsegmented axial mesoderm (the lower axis). Demonstrable effects on RNA synthesis were restricted to tissue in the lower axial region. However, inhibition of DNA synthesis was seen in tissues of the upper axis already segmented, as well as in the lower axis. The differential response of the embryonic axis to actinomycin D is considered to be based on a greater demand for cells in the unsegmented and nodal region. Actinomycin D inhibited RNA synthesis, thereby inhibited DNA synthesis and cell division, and reduced availability of cells for growth and development. The paucity of cells in the node and unsegmented axial mesoderm restricted the formation of new somites and the laying down of new nerve cord and notochordal tissue. The upper axial region was not permanently affected.

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