High-resolution organization of mouse centromeric and pericentromeric DNA

Abstract

We studied the organization of mouse satellite 3 and 4 (MS3 and MS4) in comparison with major (MaSat) and minor (MiSat) DNA sequences, located in the centromeric and pericentromeric regions of mouse telocentric chromosomes by fiber-FISH. The centromeric region consists of a small block of MiSat and MS3 followed by a pericentromeric block of MaSat with MS4. Inside the block of the long-range cluster, MaSat repeats intermingle mostly with MS4, while MiSat intermingle with MS3. The distribution of GC-rich satellite DNA fragments is less strict than that of AT-rich fragments; it is possible to find MS3 fragments in the MaSat array and MS4 fragments in the MiSat array. The methylation pattern does not fully correspond to one of the four families of satellite DNA (satDNA). In each satDNA fragment only part of the DNA is methylated. MS3 and MS4 are heavily methylated being GC-rich. Pericentomeric satellite DNA fragments are more methylated than centromeric ones. Among the four families of satDNA MS4 is the most methylated while MiSat is methylated only to a minimal extent. Estimation of the average fragment length and average distance between fragments shows that the range of the probes used does not cover the whole centromeric region. The existence of unknown sequences in the mouse centromere is likely.

A GC-rich satellite DNA and karyology of the bivalve mollusk <i>Donax trunculus:</i> a dominance of GC-rich heterochromatin

“…Although satellite repeats are regularly AT-rich, GC-rich satellites have been detected in some species (Meneveri et al, 1995;Cafasso et al, 2003), but the significance of satellite nucleotide content, if any, is not clear. It is well known that satellite families in a genome can be of different origin, and the coexistence of GC-rich and AT-rich families is not unusual and has been described in zebrafish (Sola and Gornung, 2001), mouse (Kuznetsova et al, 2006 and references therein), and proposed to exist in the scallop Adamussium colbecki (Odierna et al, 2006). Another difference of the DTF2 satellite to other D. trunculus satellite families is partial methylation of DTF2 sequences.…”

“…Another difference of the DTF2 satellite to other D. trunculus satellite families is partial methylation of DTF2 sequences. Partial satellite DNA methylation has been observed in some organisms (Kuznetsova et al, 2006 and references therein), but again, the true significance of the methylation pattern in satellite DNAs has not been determined. In the case of the DTF2 satellite, methylation could be a simple consequence of a higher number of potential susceptible sites in a GC-rich DNA sequence.…”

Human chromosome 1 satellite 3 DNA is decondensed, demethylated and transcribed in senescent cells and in A431 epithelial carcinoma cells

“…The DNA of heterochromatic pericentromeric chromosome regions is a good candidate to be the structural foundation for assembling chromocenters (Garagna et al, 2002). In mouse, DNA of well distinguishable chromocenters belongs mainly to pericentromeric regions: major satellite DNA and mouse satellite 4 (Garagna et al, 2002;Kuznetsova et al, 2005Kuznetsova et al, , 2006. However, it is not an easy task to prove the association of mouse satellite DNAs (satDNA) of different chromosomes within chromocenters as mouse satellite DNA families are species-but not chromosomespecific (Vissel and Choo, 1989).…”

Characterisation of a GC-Rich Telomeric Satellite DNA in <i>Eumeces schneideri</i> Daudin (Reptilia, Scincidae)

“…Ava II satDNA exhibited partial CpG methylation as reported for satDNAs of various organisms [e.g. Malykh et al, 2001;Barragán et al, 2002;Kuznetsova et al, 2006]. The significance of methylation is not clear [Varriale and Bernardi, 2006] and, in this case, it could be simply the consequence of the high number of CG sites in a GC-rich sequence [see Petrović et al, 2009 for a similar consideration].…”