The Evolution of satellite III DNA subfamilies among primates

Abstract

We demonstrate that satellite III (SatIII) DNA subfamilies cloned from human acrocentric chromosomes arose in the Hominoidea superfamily. Two groups, distinguished by sequence composition, evolved nonconcurrently, with group 2 evolving 16-23 million years ago (MYA) and the more recent group 1 sequences emerging approximately 4.5 MYA. We also show the relative order of emergence of each group 2 subfamily in the various primate species. Our results show that each SatIII subfamily is an independent evolutionary unit, that the rate of evolution is not uniform between species, and that the evolution within a species is not uniform between chromosomes.

Figure 1.

Representative FISH with pW-1 SatIII DNA (red) and rDNA (pA and pU6.2) (green) probes for squirrel monkey (A), baboon (B), orangutan (C), gorilla (D), chimpanzee (E), and human (F). Note the lack of hybridization signal in squirrel monkey (A) and baboon (B). Subfamily pW-1 was shown by PCR to be nonspecific in all remaining species studied except humans (see table 4).

Figure 2.

Sequence alignment, prepared using Jalview multiple-alignment editor, for the plasmid containing human pR-4 (A), human monochromosomal hybrids (B), human cell lines (C), chimpanzee (D), and gorilla (E). Dark blue indicates perfect sequence alignment across all comparisons. Light blue indicates perfect sequence alignment for some comparisons. White indicates a base change from consensus. Regions with the most-significant homology are shown.