Comparing Vertebrate Genomes

Remember the time wacky old Aunt Agnes embarrassed you at a holiday gathering? Don’t worry, there are probably much stranger relations lurking in your evolutionary past. Recent work by a group of scientists, including ASU biologist Jeff Touchman, shows that, among other things, humans are actually more closely related to rodents than to dogs or cats.

The researchers completed the first large-scale comparison of the human genome to 12 other vertebrates. Their work is an important step in understanding how vertebrate species are genetically similar or different, and provides a glimpse into the evolutionary past of humans.

Touchman also is director of the sequencing facility at the Translational Genomics Research Institute in Phoenix. The group published its findings in the Aug. 14, 2003, issue of Nature.

The scientists took a close look at segment of the human chromosome 7, which includes the gene mutated in cystic fibrosis. The report details the comparison of that segment to the same region in the genome of the chimpanzee, baboon, cat, dog, cow, pig, rat, mouse, chicken, two species of puffer fish, and the zebra fish. The research team included 71 scientists from 10 institutions.

“This is a significant genomic achievement,” Touchman says. “We can learn a lot about the human genome by comparing it to the genomes of other species. One of the things we examined was how much of the genome sequence was ‘conserved’ across organisms.”

Sequences that were conserved, or selected for retention in the genome, are thought to be strong candidates for being biologically significant to the survival of that species.

Also, by studying the differences in the genome of humans compared to other vertebrates, the researchers could determine when organisms split off and headed in different evolutionary directions.

“The work provides a first glimpse of the type of genomic studies that will occur in the future as more and more whole genomes are sequenced,” Touchman adds.—Skip Derra