Mol Gen Genet (1994) 243:369-373 © Springer-Verlag 1994 Ram S. Verma • Sunny Luke Evolutionary divergence of human chromosome 9 as revealed by the position of the ABL protooncogene in higher primates Received: 3 September 1993 / Accepted: 2 November 1993 Abstract Attempts to solve the fundamental questions regarding the descent of man are dogged by super- stitions and unexamined orthodoxies. The origin of humans, established a decade ago based upon cytologi- cal analysis of ape chromosomes, continues to be called into question. Although molecular methods have pro- vided a framework for tracing the paths of human evolution, conclusive evidence remains elusive. We have used a single ABL gene probe derived from human chromosome 9 to assess the direction of change in the equivalent ape chromosomes. This approach has resulted in a few surprises which again challenge the prevailing view of early primate evolution based solely on chromosome banding patterns. The ABL proto- oncogene is present on human chromosome 9 at band q34. Similar DNA sequences presumed to represent an ABL gene, are present on chromosome 11 in chimpan- zee (Pan troglodytes) but at a different relative location, indicating that the mechanism of the origin of human chromosome 9 is far more complex than has previously been suggested. Nevertheless, in gorilla (Gorilla 9orilla) and orangutan (Pongo pygmaeus), the equivalent to human chromosome band 9 q34 is apparently located on chromosome 13 at a putative telomeric position and no discernible differences could be established. Despite the presence of the ABL protooncogene on human equivalent ape chromosomes, molecular systematics will continue to generate enigmas in the evolutionary context until the entire genome is sequenced. Key words Primate evolution- Chromosome rearrange- ment" Fluorescence in situ hybridization (FISH)" Chro- mosome in situ suppression hybridization (CISS) • ABL oncogene Communicated by K. Illmensee R. S. Verma (~) • S. Luke Division of Genetics, The Long Island College Hospital-SUNY Health Science Center, Hicks St at Atlantic Ave., Brooklyn NY 11201, U.S.A. Introductioln Molecular methods have become a major technique for constructing phylogenetic trees for the study of human evolution (Hasegawa and Kishino 1991; Martin 1993). Chromosomal banding methods have been used to revolutionize molecular systematics (Yunis and Prakash 1982; deGrouchy 1987), yet the similarities observed by banding techniques (Minghetti and Dugaiezyk 1993; Caccone and Powell 1989) have not always been confirmed by the DNA sequence homologies observed with the chromosome in situ sup- pression hybridization (CISS) technique. When ape chromosomes were hybridized with human whole chro- mosome painting probes, the results obtained were not in agreement with existing views concerning human descent (Jauch et al. 1992; Luke and Verma 1993; Jor- gensen et al. 1992). Hypothetical scenarios will remain scientific fantasies until the boundaries between evolu- tionary divergence and similarity for humans and apes are clearly drawn. Evolutionary divergence associated with point muta- tions is part of the speciation process and views regard- ing primate evolution accepted a few years ago are constantly questioned (Caccone and Powell 1989; Ely et al. 1992). The availability of single gene probes from humans provides valuable markers for deciphering the anatomy of ape genomes. In this context, we have chosen the ABL protooncogene, which is highly conser- ved in other eukaryotes (Reddy et al. 1983). The homo- logues of the various human chromosomes in the karyotypes of apes have previously been identified by a process of elimination. Consequently, in situ hybrid- ization with the human ABL probe offered a novel approach for describing the mechanism of origin of ape chromosomes. We further utilized the ABL proto- oncogene a phylogenetic marker to trace the pathway of divergence and/or convergence of human chromo- some 9 during evolution.
