Article Abstract:
A novel regulation mechanism of Ah, or dioxin, receptor function has been found. Ah receptor (AhR), a ligand-activated transcription factor, mediates pleiotropic effects on host animals of environmental pollutants, among them 2,3,7,8-tetrachlorodibenzo-p-dioxin. Besides induction of drug-metabolizing enzymes, the liganded AhR complex activates gene expression of a factor called AhR repressor (AhRR). AhRR inhibits AhR function, competing with AhR for binding to the XRE sequence and dimerizing with AhR nuclear translocator (Arnt). AhRR and AhR make up a regulation circuit in the xenobiotic signal transduction path and give a novel regulation mecahnism for AhR function. Possibly it determines tissue-specific pollutant sensitivity.
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Article Abstract:
The bHLH gene Hes1 (ital) is required for early T cell precursor expansion. Mice mutant for the bHLH gene Hes1 (ital), known to keep cells in a state of proliferation, in the main do not have a thymus. Transferring Hes1 (ital)-null fetal liver cells to RAG2-null host mice usually reconstitutes B cells. However, mature T cells are not generated. In the reconstituted thymus, T cell differentiation is stopped at the Cd4 (super.minus)CD8(super.minus) double negative DN stage. The initial T cell receptor (TCR)-independent and the subsequent TCR-dependent selective expansion in the DN stage are much affected. Hes1 (ital), then, is needed for the first thymocyte expansion in a cell-autonomous type.
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Article Abstract:
Analysis showed that a chimeric gene had integrated into the L-chain gene on the genome of the silkworm by homologous recombination and was stably transmitted. The gene was expressed in the posterior silk gland and the gene product was spun into the cocoon layer. A recombinant virus was used to target the L-chain-GFP gene to the L-chain region of the silkworm genome, then female moths were infected with the virus and they mated. The Bombyx mori fibroin light (L)-chain gene was cloned and the green fluorescent protein (GFP) gene was inserted into exon 7. The chimeric L-chain-GFP gene was used to replace the polyhedrin gene of Autographa californica nucleopolyhedrovirus (AcNPV).
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