A homologous subfamily of satellite III DNA on human chromosomes 14 and 22

Abstract

We describe a new subfamily of human satellite III DNA that is represented on two different acrocentric chromosomes. This DNA is composed of a tandemly repeated array of diverged 5-base-pair monomer units of the sequence GGAAT or GGAGT. These monomers are organised into a 1.37-kilobase higher-order structure that is itself tandemly reiterated. Using a panel of somatic cell hybrids containing specific human chromosomes, this higher-order structure is demonstrated on chromosomes 14 and 22, but not on the remaining acrocentric chromosomes. In situ hybridisation studies have localised the sequence to the proximal p-arm region of these chromosomes. Analysis by pulsed-field gel electrophoresis (PFGE) reveals that 70-110 copies of the higher-order structure are tandemly organised on a chromosome into a major domain which appears to be flanked on both sides by non-tandemly repeated genomic DNA. In addition, some of the satellite III sequences are interspersed over a number of other PFGE fragments. This study provides fundamental knowledge on the structure and evolution of the acrocentric chromosomes, and should extend our understanding of the complex process of interchromosomal interaction which may be responsible for Robertsonian translocation and meiotic nondisjunction involving these chromosomes.

Islands of euchromatin-like sequence and expressed polymorphic sequences within the short arm of human chromosome 21

“…Cytogenetic data show that the p arms contain large heterochromatic regions (Craig-Holmes and Shaw 1971;Verma et al 1977). Molecular evidence suggests that they are composed mainly of satellite and other repeat families, including satellites I (Kalitsis et al 1993), II (Hollis and Hindley 1988), III (Choo et al 1990), ␤ (Waye and Willard 1989), and repeats ChAB4 (Cserpán et al 2002), 724 (Kurnit et al 1986), and D4Z4-like (Lyle et al 1995). These repeats have a complex pattern and are often organized in subfamilies shared between different acrocentric chromosomes and the heterochromatin of other chromosomes, for example D4Z4 (Lyle et al 1995).…”

UBF Binding In Vivo Is Not Restricted to Regulatory Sequences within the Vertebrate Ribosomal DNA Repeat

“…Interestingly, ribosomal genes appear to be the only genes found on the acrocentric p-arms. Sequences both distal and proximal to human NORs are comprised of satellite DNA packaged as heterochromatin (11,53,56,60).…”

A satellite III sequence shared by human chromosomes 13,14, and 21 that is contiguous with α satellite DNA

“…1986Frommer et al, 1982). Two subfamilies of satellite III have so far been isolated from the acrocentric chromosomes, one specific for chromosome 15 (Higgins etal.. 1985) and the other for chromosomes I4 an d 22 (Choo et al, 1990a). No satellite III subfamily has yet been reported from chromosomes 13 or 21.…”