What’s the News: Biologists have discovered an eel so bizarre that they didn’t initially know if it was an eel or some other kind of fish. The strange creature, dubbed Protoanguilla palau after a researcher found it in an undersea cavern off the coast of Palau, has very few of the anatomic features of modern eels, but displays many hallmarks of primitive eels from the Mesozoic era. It appears that the eel’s last common ancestor with any other living creature existed 200 million years ago, the researchers report in the journal Proceedings of the Royal Society B.
Swapping chromosomes among eggs could keep
embryos from inheriting genetic diseases.
What’s the News: Babies with three parents and fewer genetic diseases might soon be possible: A UK national health panel has found that techniques for swapping chromosomes between eggs so offspring don’t inherit disease-causing mutations from their mother’s mitochondria are not dangerous. The techniques, which have been tested in mice, monkeys, and human cells, still need to be studied more before making the transfer to the clinic, though, and as with all genetic engineering techniques, there’s a complex ethical maze ahead of researchers.
The good news: By combining the DNA of parents with genetic material from a third person, scientists might have developed a way for women with rare genetic disorders to have healthy children. The bad news: The ethical complications involved are so messy that it might be a long time coming.
The researchers outline their work in a study in this week’s Nature. On the surface, the idea is fairly simple. They took the nuclei out of the father’s sperm and the mother’s egg, and transplanted them into a donor’s egg cell that had its nucleus removed, but whose mitochondria remained in the cell’s cytoplasm. What you get is the genetics of both parents, plus the mitochondrial DNA of the host. This technique was pioneered in monkeys last summer, but researchers have now done a proof-of-principle study with human cells.
Mitochondria are often called cellular power plants, because they provide most of the cell’s energy. They also contain their own batch of so-called mitochondrial DNA that can, when mutated, give rise to disease. “What we’ve done is like changing the battery on a laptop,” said lead author Professor Doug Turnbull. “The energy supply now works properly, but none of the information on the hard drive has been changed. A child born using this method would have correctly functioning mitochondria, but in every other respect would get all their genetic information from their father and mother” [BBC News].
When the Vikings set sail for the British Isles they had small, furry stowaways aboard their ships, and researchers say that the descendants of those mice can offer clues about the voyages taken by Viking seafarers. A new study examined the DNA of house mice throughout the British Isles and found that mice from areas where the Vikings are thought to have settled are genetically distinct from mice in other regions.
Says study coauthor Cath Jones: “We have found that most of the mice in the north of Scotland – from Orkney, Shetland and Caithness – are all of one very similar type that we have named the Orkney lineage and they are very similar to Norwegian mice. And the only explanation for that is that when the Vikings came raping and pillaging to Scotland they took their house mice with them” [Scotsman].
For the first time, scientists have sequenced the mitochondrial DNA of a Neanderthal. Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, analyzed the genetic material from a 38,000-year-old leg bone found in Croatia and published their findings today in Cell.
The mitochondria are only passed down the female line, so can be used to trace the species back to an ancestral “Eve”, the mother of all Neanderthals. The team analysed the DNA of 13 genes from the Neanderthal mitochondria and found they were distinctly different to modern humans, suggesting Neanderthals never, or rarely, interbred with early humans. The genetic material shows that a Neanderthal “Eve” lived around 660,000 years ago, when the species last shared a common ancestor with humans [Guardian].
Cro-Magnon people and Neanderthals may have shared their European habitat from 45,000 to 30,000 years ago, but new evidence suggests that they didn’t get more intimate than that. Italian researchers sequenced mitochondrial DNA from Cro-Magnon bones dating from 28,000 years ago and found no trace of Neanderthal DNA, suggesting that the two early hominids did not interbreed to create modern humans.
The fate of the Neanderthals, who vanish from the fossil record around 30,000 years ago, has been fiercely debated. One theory, known as the Out of Africa hypothesis, holds that modern humans, whose ancestors had recently migrated from Africa, drove the Neandertals extinct, possibly through warfare, disease, or cognitive advantage. But the competing multiregional hypothesis argues that Neandertals and modern humans interbred and that Neandertals were absorbed into our gene pool [ScienceNow Daily News].
Researchers have long wondered who those rugged settlers were, and where they came from. Were they part of a massive migration that swept through all of North America, or were they a separate tribe that eventually gave rise to Greenland’s present-day Eskimos?
Until now, no ancient human remains had been found in that harsh climate to allow researchers to study the genetics of those “Paleo-Eskimos.” But the new discovery sheds some light on the people, and suggests that neither of the earlier theories is correct; in fact, they were a distinct tribe that journeyed all the way from Siberia to Greenland, but didn’t stick around to populate the frozen north.