Arcyptera fusca and Arcyptera tornosi repetitive DNA families: whole‐comparative genomic hybridization (W‐CGH) as a novel approach to the study of satellite DNA libraries

Abstract

Whole‐comparative genomic hybridization (W‐CGH) has been used to exemplify a simple methodology which allows identifying and mapping whole genome differences for highly repetitive DNA sequences between two related species of unknown genomic background. The use of this technique to the species binomy Arcyptera fusca/Arcyptera tornosi has allowed the identification of different DNA families mainly concentrated within the para‐/peri‐centromeric and distal heterochromatic regions of different chromosomes, which are differentially expanded in both genomes. Additionally, W‐CGH allowed chromosome mapping of particular euchromatic regions immersed in the chromosome arms which have been affected by processes of DNA amplification and losses. A molecular approach was also conducted to analyse satellite DNA families in these species. We have found three different families showing an unequal representation in both species. Two of these families showed a centromeric location (EcoRV‐390CEN and Sau3A‐419CEN), whereas the last one was located at distal heterochromatic regions (Sau3A‐197TEL). As A. fusca is a widely distributed species represented in most European high mountains, whereas A. tornosi is an endemic species represented in the Iberian Peninsula, the differences and resemblances reported here offer a good basis to support a close evolutionary relationship between both of the actually isolated species. Finally, W‐CGH allowed identification of an asynchronic pattern of heterochromatin condensation through early prophase (characteristic in both species) which is uncommon or probably has been poorly analysed within classical early condensing chromosome domains through meiosis. The congruence of the obtained cytological and molecular results is analysed in light of the ancestral genome relationship between both species.

Constitutive heterochromatin polymorphisms in human chromosomes identified by whole comparative genomic hybridization

“…This technique has provided evidence for the presence of polymorphisms in insects where knowledge about the presence of these polymorphisms was low and mainly constrained to variations in C-banded regions. 13 In mammalian species, unexplored polymorphisms were identified in swine, sheep, stallion, and donkey, 14–16 and the technique also provided evidence for the presence of highly conserved repetitive DNA sequences on chromosome 9 when human and gorilla chromosomes were compared. 17 Accordingly, W-CGH is a reliable tool for the comparison of the levels of polymorphism of repetitive DNA sequences in the human genome, giving a one-shot experimental hybridization for comparing two different genomes.…”

Whole-comparative genomic hybridization in domestic sheep <i>(Ovis aries)</i> breeds

“…Distant breeds, as in this case the synthetic hybrid Assaf, chosen for this particular experiment for being such a random breed, tend to show differences. The conclusions reached in this experiment using W-CGH in sheep as well as other recent experiments studying different breeds of pig (Pita et al, 2008a) along with those investigating different species within the same genus as in the grasshopper Arcyptera (Pita et al, 2008b) reinforce the potential use of W-CGH as a simple strategic, informative technique for comparing genomes. W-CGH is of particular interest for performing early studies between breeds and species of which deep molecular studies have yet to be done and only a poor genomic background is available.…”

Shared Y chromosome repetitive DNA sequences in stallion and donkey as visualized using whole-genomic comparative hybridization

“…20 For instance, W-CGH performed using two closely related grasshoppers, produces results on some autosomes similar to those reported here for the Y chromosome. 8 The results obtained in grasshoppers were identical irrespective of the species employed as the chromosomal strip for probe landing. This fact suggested that, in addition to heterochromatic compartmentalization on constitutive heterochromatin, variation in sat-DNA family copy number, rather than sequence divergence, may account for the differential presence of DNA families in the species compared.…”