The heat shock response in Xenopus oocytes, embryos, and somatic cells: a regulatory role for chromatin

Article Abstract:

Many of the genes active in oocytes are transcriptionally repressed in somatic cells. This repression phenomenon was studied further by expressing the Xenopus hsp70 promoter and mutants in oocytes, embryos and somatic cells. At first, a large variation in promoter activity suggested developmental regulation of gene expression. However, it then became apparent that the capacity of the hsp70 promoter to be transcriptionally activated following heat shock depended on the assembly of the promoter into chromatin. The Xenopus oocyte and Xenopus hsp70 promoter were thus established as a heat shock-responsive system.

Physiological aspects

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Transcriptional activation of the matrix metalloproteinase gene stromelysin-3 coincides with thyroid hormone-induced cell death during frog metamorphosis

Article Abstract:

Sequence analysis of a cloned full-length frog cDNA of a thyroid hormone response gene in the metamorphosing frog intestine reveals it as the frog homolog of the mammalian extracellular matrix metalloproteinase stromelysin-3 (ST3). Northern hybridization reveals the differential activation of ST3 gene expression in tadpole tissues during metamorphosis. During thyroid hormone-induced metamorphic apoptosis the extracellular matrix is modified by ST3.

Analysis, Cell death, Amphibians, Metalloenzymes, Metamorphosis (Biology)

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Developmental roles for chromatin and chromosomal structure

Article Abstract:

The nuclear environment of a cell has a strong influence on the regulation of gene expression. Chromatin structure and particular transcription factors determine the states of nuclear activity during development. Genetic experiments in the growing embryos of Caenorhabditis elegans, Drosophila melanogaster and the mouse provide evidence on the developmental control of gene function. Some of these studies are discussed.

Chromosomes

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