engleski

Analysis of nucleosome arrangement on Tenebrio molitor satellite DNA

The nucleosomal arrangement on satellite DNA of Tenebrio molitor beetle (Tenebrionidae, Coleoptera) has been studied. A single satellite DNA constitutes about half of the T. molitor genome. Very regular nucleosomal ladder consisting of about 170 bp long multimers was obtained after digestion of crude chromatin extract with micrococcal nuclease. All ladder rungs hybridized intensively with the satellite DNA probe, indicating uniform distribution of satellite-DNA bearing nucleosomes in the digested material. From the total population of fragments, satellite-containing fragments were selected after cloning and hybridization, and nucleotide sequences of these clones were determined. Sequence analysis indicates that microccocal nuclease suspectible sites defined by nucleotide sequence were cleaved in preference, and assumably disregarding the nucleosomal positions. This effect might be a consequence of an extremely dense packing of nucleosomes in T. molitor heterochromatin because of putative tightly bound additional protein components, that remain under the isolation procedure. To circumvent this problem we are currently isolating core DNA fragments prepared from T. molitor nuclei using micrococcal nuclease, exonuclease III and nuclease S1.

satellite DNA; nucleosome; heterochromatin

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