engleski

Mosaic organization of satellite DNA sequences in Tenebrio molitor heterochromatin

Extensive characterisation of both structure and organization of heterochromatic DNA will enable us to discern function of particular heterochromatic regions, such as centromeres and telomeres. Previous cytogenetic characterisation shows that heterochromatin of Tenebrio monitor (Insecta, Coleoptera) is pericentromerically located and contains abundant satellite DNA. The results presented where've insight into general organization of DNA sequences within the heterochromatin of T. monitor. Southern hybridisation analysis of pulsed-field blots reveals that major satellite DNA is organised in clusters ranging in size from 70 kb to 1 Mb. more detailed information about satellite DNA organization was obtained by FISH on extended DNA fibers. Major satellite DNA comprises 66%of heterochromatic region and is organised in uninterrupted arrays ranging in size from 6 kb to 116 kb, with the average length of 28 kb. These arrays are interspersed with other sequences, represented as gaps of average size of 11 kb. Comparison of pulsed-field and FISH data indicates that those gaps do not contain complex DNA but rather other satellite DNAs. Heterochromatin of T. monitor consists of long clusters of satellite DNAs ; within those clusters, different satellite sequences are organized as highly interspersed short arrays. This organization is different from that in many animal and plant species, in which repetitive sequences are organise in long separate domains. However, such mosaic organization is comparable to the one previously described for tenebrionid species Tribolium maidens, and is possibly induced by a high rate of inter chromosomal exchange characteristic for the family Tenebrionidae.

Satellite DNA, heterochromatin, (peri)centromeric DNA, evolution, Tenebrio molitor, organizational pattern

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