Genome Research is publishing several papers related to analyses of the amphioxus (Branchiostoma floridae) genome sequence. The amphioxus, or lancelet, is a cephalochordate residing in shallow regions of tropical and temperate seas, bearing resemblance to a small fish, however lacking pairs of eyes, limbs, and ears. A member of the chordata phylum along with tunicates (sea squirts) and vertebrates, amphioxus lacks the backbone or spinal column characteristic of vertebrate animals, yet shares the same basic body plan. Amphioxus is therefore an excellent model for investigating how vertebrates evolved from an invertebrate ancestor. Now, researchers are finding that the amphioxus genome sequence is revealing new insights into vertebrate origins and the evolution of complex biological systems, such as immunity and nervous system development. Primary research reports describing these novel findings will be published online June 19, concurrent with publication of the amphioxus genome sequence report in the journal Nature.

“From a basic science perspective, the advances being made in genomics are important discoveries, but it’s unrealistic for individuals to believe those advances can yield meaningful information that will improve their health,” said James P. Evans, M.D., Ph.D., professor of genetics and medicine in the UNC School of Medicine. “And even saying ‘It’s not there yet’ is too optimistic. It’s going to be a long time before the potential is realized.”

Evans, who is also the director of the cancer and adult genetics clinics and the Bryson Program in Human Genetics in UNC’s medical genetics department, will talk about how personal genomics will affect human lives at a panel discussion titled “Your Biological Biography” at the World Science Festival being held in New York City, May 28 to June 1. Evans will speak between 1 p.m. and 2:30 p.m. on Saturday, May 31, at the Kimmel Center for University Life at New York University.

“The sequencing of the human genome revealed that in relative terms, humans are 99.9 percent the same,” Evans said. “But in absolute terms, we are very different. For example, a one-thousandth of a difference in their respective DNA profiles translates into more than 3 million differences between any two unrelated individuals.”

Some of these differences are medically relevant, in that they influence disease predisposition and response to drugs, areas Evans studies in his research. And the differences are of interest in non-medical ways, specifically when they address ancestry, behavior traits and the innate curiosity humans have about their genes.

Sequencing of the human genome, which was completed in 2003, also gave rise to commercial entities offering direct-to-consumer genetic testing for a fee, usually between $1,000 and $3,000. Evans worries that individuals may seek such testing with the false hope that they will get meaningful results regarding their risks for disease and actionable medical advice about how to decrease their risks.

“Much of the current excitement about genetics and medical genomics is predicated on the idea that knowing our genomes better will improve our health,” Evans said. “In fact, for the vast majority of such risk assessments, the increased risk of an individual developing the disease in question is modest – one- to two-fold over baseline. And in few such conditions are there specific effective interventions to diminish the risk. Further, there is little evidence that having the specific genetic information would actually induce a change in lifestyle.”

Society has tended to place an almost mystical association on genetic information, Evans said, adding that what to do with this new knowledge and how to interpret the information presents many unanswered challenges.

“Most physicians, by their own admission, are not geneticists and won’t know what to do with the information,” said Evans, who uses family history and genetic testing to evaluate and counsel patients about their risk for cancer. “Many who do understand the technology and how it is generated don’t know what to do with it. So there’s huge potential for patient harm – either for patients to be lulled into a false sense of security by this new genomic information or, in the opposite extreme, to have unnecessarily increased anxiety.”

And Evans said he can see even more extreme measures “where interventions are implemented – for example, a total body scan – that put patients on a road to invasive tests that they are better off not getting.”

Evans believes these challenges say something about how humans value information, but then fail to scrutinize what it really means. “It’s hard for me to over-estimate the beauty and utter significance of sequencing the human genome and other animal genomes,” Evans said. “The technology is very promising for all of us, but there is a big gap between having that knowledge and applying it for the betterment of human health.”

Long viewed as straitlaced spinsters, sexless freshwater invertebrate animals known as bdelloid rotifers may actually be far more promiscuous than anyone had imagined: Scientists at Harvard University have found that the genomes of these common creatures are chock-full of DNA from plants, fungi, bacteria, and animals.The finding, described this week in the journal Science, could take the sex out of sexual reproduction, showing that bdelloid rotifers, all of which are female, can exchange genetic material via other means.

“Our result shows that genes can enter the genomes of bdelloid rotifers in a manner fundamentally different from that which, in other animals, results from the mating of males and females,” says Matthew S. Meselson, Thomas Dudley Cabot Professor of the Natural Sciences in Harvard’s Faculty of Arts and Sciences.

In essence, Meselson and colleagues say, bdelloids may acquire DNA by habitually disintegrating their genomes — something these unusual animals do regularly during periods of desiccation, which fractures their genetic material and ruptures cellular membranes. Miraculously, bdelloids can then spring back to life upon rehydration of their habitats, readily reconstituting their genomes and their membranes.

In the process of rebuilding their shattered DNA, though, they may adopt shreds of genetic material from other bdelloids in the same puddle, as well as from unrelated species.

Meselson and co-authors Eugene A. Gladyshev and Irina R. Arkhipova believe the findings may solve the longstanding mystery of bdelloids’ sexless ways, and may shed light on their ability to adapt to new environments.

“These fascinating animals not only have relaxed the barriers to incorporation of foreign genetic material, but, more surprisingly, they even managed to keep some of these alien genes functional,” says Arkhipova, a staff scientist in Harvard’s Department of Molecular and Cellular Biology.

“In principle, this gives them an opportunity to take advantage of the entire environmental metagenome,” adds Gladyshev, a graduate student in molecular and cellular biology at Harvard.

While the scientists have yet to pinpoint the exact sources of the invasive DNA, they have ascertained that the foreign genes are concentrated in bdelloid telomeres, the regions at the ends of DNA thought to prevent its strands from unraveling — much like the plastic cap on the end of a shoelace.

A next step, Meselson says, is to determine whether bdelloid genomes also contain homologous genes imported from other bdelloids. He and his colleagues also hope to examine whether the animals actually use any of the hundreds of snippets of foreign DNA they appear to vacuum up.

Nearly all other multicellular animals have strong safeguards against foreign DNA, but bdelloids’ seeming embrace of genetic detritus is in keeping with their general quirkiness: Shunning sex and entirely lacking males, the ubiquitous creatures are also extraordinarily resistant to radiation, as Meselson and Gladyshev demonstrated earlier this year in a paper published in the Proceedings of the National Academy of Sciences.

With nearly 500 recognized species worldwide, bdelloid rotifers were discovered in 1702, when the renowned Dutch scientist and microscopy pioneer Antony van Leeuwenhoek added water to dust retrieved from a rain gutter on his house and observed the organisms in the resulting fluid. He subsequently described the creatures in a letter to Britain’s Royal Society, which still counts an envelope of van Leeuwenhoek’s rain-gutter dust among its holdings.