DNase I sensitivity in facultative and constitutive heterochromatin.
In situ nick translation allows the detection of DNase I sensitive and insensitive regions in fixed mammalian mitotic chromosomes. We have determined the difference in DNase I sensitivity between the active and inactive X chromosomes in Microtus agrestis (rodent) cells, along both their euchromatic and constitutive heterochromatic regions. In addition, we analysed the DNase I sensitivity of the constitutive heterochromatic regions in mouse chromosomes. In Microtus agrestis female cells the active X chromosome is sensitive to DNase I along its euchromatic region while the inactive X chromosome is insensitive except for an early replicating region at its distal end. The late replicating constitutive heterochromatic regions, however, in both the active and inactive X chromosome are sensitive to DNase I. In mouse cells on the other hand, the constitutive heterochromatin is insensitive to DNase I both in mitotic chromosomes and interphase nuclei.
D000818:Animals; D003411:Arvicolinae; D002478:Cells, Cultured; D002872:Chromosome Deletion; D004261:DNA Replication; D003850:Deoxyribonuclease I / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D006570:Heterochromatin / Q000378:metabolism* / Q000648:ultrastructure; D007399:Interphase; D008938:Mitosis; D014176:Protein Biosynthesis; D014960:X Chromosome
D006570:Heterochromatin; D003850:Deoxyribonuclease I