Transcriptional activation of puff site I-18C of Chironomus tentans: Hormonal responsiveness changes in parallel with diurnal decondensation cycle
| Autor: | Friederike Gatzka, Alexey D. Gruzdev, Hannes Ineichen, Markus Lezzi |
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| Rok vydání: | 1991 |
| Předmět: |
Regulation of gene expression
medicine.medical_specialty education.field_of_study Ecdysterone Population Biology Cell biology Endocrinology Hormone receptor Diurnal cycle Premature chromosome condensation Internal medicine Genetics medicine Circadian rhythm education Developmental biology Genetics (clinical) |
| Zdroj: | Chromosoma. 100:235-241 |
| ISSN: | 1432-0886 0009-5915 |
| Popis: | The morphology of region I-18C of the salivary gland chromosomes of oligopausing larvae (stage 5) of Chironomus tentans changes with a diurnal cycle. In the dark period it is usually decondensed while in the light period it is mostly condensed. However, 3 h after the beginning of the light period, region I-18C temporarily decondenses whereas 3 h after the onset of the dark period it condenses transiently. This complex diurnal decondensation pattern is specific for region I-18C as Balbiani ring 2 expansion and total chromosome I lengthening exhibit different diurnal patterns. The diurnal course of I-18C decondensation is partially paralleled by changes in its responsiveness towards ecdysterone. During the condensation periods, a fraction of the chromosome I population becomes refractory and the hormone can no longer induce transcriptional activity in region I-18C. Measurements with intracellular K+-specific microelectrodes indicate that nuclear K+ activity follows the same diurnal pattern as I-18C decondensation and hormonal responsiveness. The results are interpreted in terms of the two-step model of gene activation according to which ion-induced local chromatin decondensation represents a prerequisite for hormone receptor interaction with DNA and subsequent transcription initiation. |
| Databáze: | OpenAIRE |
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