Search results for "Position-effect variegation"
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Instability of Tandem Repetitive DNA in “Natural” and Transgenic Organisms
1996
Genome research of the last 10 years has forced us to re-evaluate our view of DNA as a relatively stable molecule. Unprecedented levels of DNA instability in germline and soma cells have been observed, associated primarily with tandem repetitive (tr) DNA sequences. We will discuss here briefly the structure and possible functions of trDNA in eukaryotes, the putative mechanisms of mutational change in repeat clusters and the evolutionary dimensions of trDNA instability (for other relevant reviews, sec Pardue and Hennig 1990; Vogt 1990; Charlesworth et al. 1994). A special focus will be on the behaviour of trDNA after DNA transfer experiments in transgenic organisms, with reference to our own…
Linker histone H1 is essential for Drosophila development, the establishment of pericentric heterochromatin, and a normal polytene chromosome structu…
2009
We generated mutant alleles of Drosophila melanogaster in which expression of the linker histone H1 can be down-regulated over a wide range by RNAi. When the H1 protein level is reduced to ∼20% of the level in wild-type larvae, lethality occurs in the late larval – pupal stages of development. Here we show that H1 has an important function in gene regulation within or near heterochromatin. It is a strong dominant suppressor of position effect variegation (PEV). Similar to other suppressors of PEV, H1 is simultaneously involved in both the repression of euchromatic genes brought to the vicinity of pericentric heterochromatin and the activation of heterochromatic genes that depend on their pe…