Scientists find first active ‘jumping genes’ in rice

Researchers studying rice genomes have identified the species’ first active DNA transposons, or “jumping genes.” The scientists also discovered the first active “miniature inverted-repeat transposable element,” or “MITE,” of any organism. Rice (Oryza sativa), an important food crop worldwide, has the smallest genome size of all cereals at 430 million base pairs of DNA. About 40 percent of the rice genome comprises repetitive DNA that does not code for proteins and thus has no obvious function for the plant. Much of this repetitive sequence appears to be transposons similar to MITEs. But like most genomes studied to date, including the human genome, the function of this highly repeated so-called “junk DNA” has been a mystery. The discovery of active transposons in rice provides startling new insights into how genomes change and what role transposons may play in the process.

Slice that DNA carefully

The genome of the pufferfish, a Japanese delicacy, is teaching researchers about the more complex genetic makeup of humans. The pufferfish, or Fugu, has about the same number of genes as humans, but without most of the repetitive “junk” DNA found in naked apes, researchers at the Joint Genome Institute in Walnut Creek, California, report. Fugu can pack a lethal tetrodotoxin whallop, but manages to do so with the smallest genome of any vertebrate. The findings were detailed in the journal Science and reported on by the Associated Press.