The location of four human satellite DNAs on human chromosomes

185

136

Highly conserved repetitive DNA sequence clones, largely consisting of (GGAAT HeLa-ceil nuclear proteins recognize this sequence with a relative affinity >105. The extreme evolutionary conservation ofthis DNA sequence, its centromeric location, its unusual hydrogen bonding properties, its high affinity for specific nuclear proteins, and its similarity to functional centromeres isolated from yeast suggest that this sequence may be a component of the functional human centromere.

Section: Resultsmentioning

confidence: 99%

Highly conserved repetitive DNA sequences are present at human centromeres.

Grady

Ratliff

Robinson

et al. 1992

185

136

“…The major site ofhybridization in both cell lines was the centromere region of the X chromosome. In addition, analysis of several chromosomal spreads on (20).…”

Section: Methodsmentioning

confidence: 99%

Characterization of a cloned repetitive DNA sequence concentrated on the human X chromosome.

Yang¹,

Hansen²,

Oishi³

et al. 1982

123

A tandemly repeated DNA sequence organized predominantly, if not entirely, in a specific manner on the human X chromosome has been cloned in pBR322 and characterized. The sequence was detected as a 2-kilobase band in ethidium bromidestained agarose gels ofBamHI-digested total human nuclear DNA. Although in situ hybridization of the cloned sequence to human metaphase chromosomes showed a single major site of hybridization at the centromere region ofthe X chromosome and minor sites of hybridization at several autosomal centromeres, Southern blot analysis of restricted total human DNA indicated that the cloned probe is related to other repeated DNAs, particularly the human alphoid DNAs. Restriction enzyme analysis ofthe cloned fragment revealed an internal repeat structure based upon multiples of 170 base pairs, confirming this relatedness. All available data, however, suggest that the 2-kilobase spacing ofBamHI sites within the repeat may be specific to the X chromosome.The human X chromosome is a particularly interesting system for the molecular investigation of mammalian gene structure expression. A large number ofmedically significant genetic loci have been mapped to it; and one X chromosome in female eutherian mammals exhibits the phenomenon of inactivation, apparently to accomplish dosage compensation of X-linked gene functions (1). Thus, with appropriate DNA probes, this system provides the opportunity to analyze molecular properties ofthe same gene in the active as well as the inactive state in the same cell.Recent advances in DNA technology in conjunction with modem genetic methods have permitted the identification or isolation of X-chromosome specific human DNA sequences. Beauchamp et al. (2) used Southern blot analysis to identify a 2-kilobase-pair (kb) fragment generated by BamHI digestion of rodent-human somatic cell hybrid DNA present in hybrids containing the human X chromosome and which bears homology to human satellite III DNA. Recently, several single-copy sequences from mammalian X chromosomes have been cloned. These include cDNA of the human glucose-6-phosphate dehydrogenase gene (3), a partial cDNA clone of the mouse hypoxanthine phosphoribosyltransferase gene (4), an unidentified human single-copy DNA sequence (5), and two A libraries constructed from flow-sorted chromosomes enriched in human X (6, 7). To date, however, no cloned repetitive sequences that are located predominantly or entirely on the human X chromosome have been reported.We report the cloning and characterization of a 2-kb fragment of human DNA which exists in tandem arrays and is concentrated at or near the centromere region ofthe human X chromosome. The spacing of BamHI sites argues that it is homologous to the sequence noted by Beauchamp et al. (2). Restriction enzyme analysis of the DNA provides data to support the hypothesis that the organization of this sequence is predominantly, if not entirely, specific to the X chromosome. In addition, the DNA displays homology to the human EcoRI dimer and similarities to othe...

“…Somatic cell hybrid mapping and in situ hybridization have identified pB4 /3 satellite domains on each of the acrocentric chromosomes. Several reports have previously identified a variety of repetitive sequences that are localized to the acrocentric short arms (9)(10)(11)(12)18) or centromeres (13)(14)(15). In one such study (published while this work was in progress), a cloned -67-bp Sau3A fragment was shown to hybridize in situ to the acrocentric short arms (11).…”

mentioning

confidence: 96%

“…A second class of sequences, a satellite, consists of =171-base-pair (bp) tandem repeat units localized to the centromeric region of each human chromosome (8). Although both of these major classes of human satellite DNA are organized in a largely chromosome-specific manner, a notable exception involves sequences at the centromere and on the short arms of the five pairs of acrocentric chromosomes (9)(10)(11)(12). Repetitive DNA sequences and the ribosomal RNA (rRNA) genes localized to these chromosomes do not exhibit chromosome specificity but rather demonstrate complex patterns of interchromosomal homology, reflecting partial or complete sequence homogenization and concerted evolution (13)(14)(15)(16)(17)(18).…”

mentioning

confidence: 99%

Human beta satellite DNA: genomic organization and sequence definition of a class of highly repetitive tandem DNA.

Waye

Willard

1989

130

We describe a class of human repetitive DNA, called (3 satellite, that, at a most fundamental level, exists as tandem arrays of diverged -68-base-pair monomer repeat units. The monomer units are organized as distinct subsets, each characterized by a multimeric higher-order repeat unit that is tandemly reiterated and represents a recent unit of amplification. We have cloned, characterized, and determined the sequence of two (3 satellite higher-order repeat units: one located on chromosome 9, the other on the acrocentric chromosomes (13, 14, 15, 21, and 22) and perhaps other sites in the genome. Analysis by pulsed-field gel electrophoresis reveals that these tandem arrays are localized in large domains (50-300 kilobase pairs) that are marked by restriction fragment length polymorphisms. In total, .8 satellite sequences comprise several million base pairs of DNA in the human genome. Analysis of this DNA family should permit insights into the nature of chromosome-specific and nonspecific modes of satellite DNA evolution and provide useful tools for probing the molecular organization and concerted evolution of the acrocentric chromosomes.It has been recognized for nearly 20 years that a considerable proportion of the human genome consists of constitutive heterochromatin, regions known to be rich in highly repetitive "satellite" DNA (1, 2). Recently, considerable progress has been made toward the systematic classification of satellite DNAs based on the size and composition, as well as the genomic distribution and subchromosomal localization, of the tandem repeat unit. Studies employing cloned satellite probes have revealed the existence of two broad classes of human satellite DNA. One class of sequences, comprising the major components of several classical satellite DNAs originally isolated by altered buoyant density (base composition), consists of relatively short oligonucleotide tandem repeat units organized in long chromosome-specific arrays. These sequences are located primarily in the heterochromatic long arm regions of human chromosomes 1, 9, 16, and Y (3-7). A second class of sequences, a satellite, consists of =171-base-pair (bp) tandem repeat units localized to the centromeric region of each human chromosome (8). Although both of these major classes of human satellite DNA are organized in a largely chromosome-specific manner, a notable exception involves sequences at the centromere and on the short arms of the five pairs of acrocentric chromosomes (9-12). Repetitive DNA sequences and the ribosomal RNA (rRNA) genes localized to these chromosomes do not exhibit chromosome specificity but rather demonstrate complex patterns of interchromosomal homology, reflecting partial or complete sequence homogenization and concerted evolution (13-18).In this report, we describe the isolation and characterization of a human satellite DNA family, f satellitet which is unrelated in structure or sequence to any previously described human satellite DNAs. These sequences comprise a minimum of several million base pairs o...