One of the commonly heard refrains about non-human primates is that since they are close to humans genetically, they should be granted rights. If that’s the case, then what about the poor pufferfish?
The pufferfish is largely known for its potential to kill those who eat it. The pufferfish contains a neurotoxin and, if not prepared properly, can quickly kill a human being who eats it (which, of course, makes it all that much more interesting for thrill seekers).
The pufferfish is also of great interest to medical researchers, however, who are busy trying to sequence its genome. What might surprise a lot of people is that the odd-looking pufferfish is genetically very similar to human beings, which is what makes it of such potential use in research.
“In terms of gene complement, we are least 90% similar — probably higher,” said Greg Elgar, who heads up the effort to sequence the pufferfish genome. “There are big differences in gene expression levels and alternate transcripts, but if you’re talking about diversity, number and types of proteins, then it’s pretty difficult to tell us apart.”
Last October, Elgar announced that one species of pufferfish, Fugu rubripes had been sequenced, and sequencing of another species, Tetraodon nigroviridis, is under way.
Aside from the similarity with the human genome, the other advantage of sequencing the pufferfish genome is that it is relatively small — only about one-tenth the size of the human genome. This is because it lacks the so-called “junk DNA” present in many species, including human beings. This makes it easier for researchers to determine the function of the DNA. According to Elgar,
We’re pretty good at spotting coding sequences, mostly through cDNAs and EST [expressed sequence tags] work, but we’re very poor at finding regulatory sequences, basically because no one knows what we’re looking for. These control sequences are often shared between Fugu and mammals, and because the rest of the ‘junk’ is not well conserved, as it often is when you compare mouse and man, they stand out and slap you if you know how to look.
Already, the pufferfish effort has led to important findings about the human genome. For example, one of the things of interest to researchers are evolutionarily conserved regions (ecores) — these are parts of the genetic makeup of animals that exist across species and are the result of a shared evolutionary past.
Because the pufferfish genome lacks much of the junk DNA that makes it difficult to spot ecores, researchers were able to use the pufferfish to identify 207 new ecores between humans and other species.
Source:
Pufferfish genomes probe human genes. Ricki Lewis, The Scientist, 16[6]:22, March 18, 2002.