Interspersed repeated sequences in the African green monkey genome that are homologous to the human Alu family

Abstract

The dominant family of interspersed repetitive DNA sequences in the human genome has been termed the Alu family. We have found that more than 75% of the X phage in a recombinant library representing an African green monkey genome hybridize with a human Alu sequence under stringent conditions. A group of clones selected from the monkey library with probes other than the Alu sequence were analyzed for the presence and distribution of Alu family sequences. The analyses confirm the abundance of Alu sequences and demonstrate that more than one repeat unit is present in some phages. In the clones studied, the Alu units are separated by an average of 8 kilobase pairs of unrelated sequences. The nucleotide sequence of one monkey Alu sequence is reported and shown to resemble the human Alu sequences closely. Hence, the sequence, dispersion pattern, and copy number of the Alu family members are very similar in the African green monkey and human genomes.Among the clones investigated were two that contain segments of the satellite DNA termed o-component joined to non o-component DNA. The experiments indicate that in the monkey genome Alu sequences can occur close to regions of a-component DNA.

Interruption of an alpha-satellite array by a short member of the KpnI family of interspersed, highly repeated monkey DNA sequences.

“…KpnI-RET contains no long significant homologies to the sequence of human 7S RNA (30), monkey Alu sequences (8,9), ax-satellite (21), or the 1.9-kbp-long HindlIl fragment (15) that is part of the human and monkey KpnI family of long interspersed repeats (10,15,17,24,26).…”

“…(B) XCaa6 and XCaa7 (1 ,ug) (8,10,19). (C) Schematic diagrams of the KpnI family segments in XCaa6 and XCaa7 (8,10,19). Only a few restriction endonuclease sites are shown.…”

“…portion of the KpnI family members (Fig. 3C) and a portion of the right arm of the X Charon 4A vector; in XCaa6 it also includes a short stretch of a-satellite sequence (8,10).…”

Unusual class of Alu sequences containing a potential Z-DNA segment.

“…This Alu, bounded by imperfect direct repeats, also contains an unusual 3' end and may be a member of a large subfamily of such 2,4,5,15,18,20), suggesting a possible target site duplication resulting from insertion of a moveable Alu element (9). This model is supported by the fact that an Alu sequence that interrupts monkey a-satellite is flanked by direct repeats of a 13-bp-long segment that occurs only once at the target site in the uninterrupted asatellite consensus sequence (6).…”

“…The presence of Alu sequences in XCaOri7 was originally determined by hybridization of the human Alu subclone BLUR8 (17) or a monkey Alu to a Southern blot of phage restriction digests (5). The fragment containing the variant Alu hybridized much less with both of these probes than did the other Alu containing fragments of XCaOri7.…”