Posted by Those of us who work on non-human systems often grumble about the total disregard human geneticists (that’s geneticists who study humans, not humans who are geneticists) have toward non-human research (that’s research on non-humans, not non-humans doing research). I get the feeling that plant biologists have the same attitude toward non-plant researchers, and I imagine there is some unwritten chain of superiority wherein you must pay respect to the researchers working on a system “above” you and ignore the research done on a system “beneath” yours — and, yes, I realize the higher and lower thing is bullshit.
Now for a specific example: Much work has been done in the area of genome rearrangements using non-human systems. A lot of this work has been done in Drosophila, but the human geneticists often neglect this body of work when discussing the recently discovered plethora rearrangements in the human genome (ie, this and this). A recent paper in PNAS exemplifies this behavior. Granted, the paper is from a group that “has focused on the study of chromosomal rearrangements in the bacterial genome”, and they’ve only recently begun studying the human genome. But that’s not excuse to not be familiar with the Drosophila literature that predates any other studies of chromosomal rearrangements.
The article mentioned above presents research on the types of DNA sequences that can induce inversion events. Inversion breakpoints tend to have sequences with high identity located at the pairs of breakpoints. Those high identity sequences may pair up and illegitimately recombine, inducing an inversion event. The authors refer to this as nonallelic homologous recombination (NAHR), which screams out “HEY EVERYBODY, I’M A MOLECULAR BIOLOGIST UNFAMILIAR WITH THE PROPER DEFINITION OF HOMOLOGY!” It’s really just non-allelic recombination — there is no need and no justification to refer to homology.
The publication heavily cites the recent literature on segmental duplications and inversions in the human genome, of which there is quite a lot. But there is not a single citation to any Drosophila research. It’s hard to imagine that, in a paper dealing with repeat induced rearrangements in a eukaryotic genome, the authors fail to cite anything by Bill Engels (here would be a good place to start). Do the authors not know about the Drosophila literature? Do they not care to know? Do they take the attitude that if it’s done in humans it’s more important, and, therefore, there is no need to cite the previous research which discovered similar things in non-human systems?
Additionally, this brings up the broader question of the use of model organisms in genomics. Prior to the human genome project, non-human systems were quite useful for studying phenomena that could not be examined in humans. This is still the case in many other biological subdisciplines where analyzing mutants, studying many nearly identical individuals, or sacrificing organisms is required. But genomics relies only on DNA sequences, which can be obtained from any organism. And, as it currently stands, human sequence data are among the best for doing genomics, in terms of the quality of the sequence, the freely available polymorphism data, and the sequences available from closely related taxa.
What use are model organisms if we can do the same analyses in humans? First off, this question assumes that the purpose of studying non-human models is so that we can better understand humans. That’s not necessarily the case, as many non-human studies are for the purpose of increasing our understanding of all biology. Not all of the life sciences are dedicated towards improving the well being of some arrogant biped. Furthermore, a lot science is about finding generalities that apply broadly to many different systems. Studying diverse models allow us to identify commonalities shared by many taxa, as well as differences between those taxa.
With that in mind, we must redefine what it means to be a model organism for the purpose of genomics. These are not models of human biology and disease. These are models of all life. We should sample organisms from various diverse taxa to determine what genomic features that have in common, how they differ, and how these features evolve. And that’s another thing missing from the article discussed above — implications for evolution. To compare, here is the most recent article I’ve come across on chromosomal rearrangements in Drosophila. I’m a bit biased, but I like the Drosophila article much better.
April 11, 2007
April 11, 2007
April 11, 2007
April 11, 2007
April 11, 2007
April 12, 2007
April 12, 2007