In their search for the lost grave of King Richard III, archaeologists unearthed a skeleton from underneath a parking lot last August. Today researchers announced that the skeleton is indeed that of England’s 500-year-deceased
king, and they have the DNA and radiocarbon dating to prove it.
Richard III is most famous for the Shakespeare play of the same name, which was written a century after his death. This English king reigned for just over two years, but his body was buried without record of its exact location. Researchers began digging up the vicinity of Greyfriars church in Leicester in 2011, and today’s announcement is the scientific evidence they needed to make their case for a definitive identification.
DNA is the building block of life, but in the future it may also be the standard repository for encyclopedias, music and other digital data. Scientists announced yesterday that they successfully converted 739 kilobytes of hard drive data in genetic code and then retrieved the content with 100 percent accuracy.
The researchers began with the computer files from some notable cultural highlights: an audio recording of MLK Jr.’s 1963 “I Have a Dream” speech, all 154 of Shakespeare’s sonnets, and, appropriately, a copy of Watson and Crick’s original research paper describing DNA’s double helix structure. On a hard drive, these files are stored as a series of zeros and ones. The researchers worked out a system to translate the binary code into one with four characters instead: A, C, G and T. They used this genetic code to synthesize actual strands of DNA with the content embedded in its very structure.
What does DNA look like? According to the biology textbooks of the last half century, it consists of a twisting ladder of base pairs: A with T and C with G. But a new study in Nature presents evidence that some human DNA may actually have four strands instead of two, and researchers say the quadruple helix may be linked to cancer.
The now-ubiquitous double-helix structure was first published in the journal Nature in 1953 by scientists James Watson and Francis Crick from the University of Cambridge. Nearly 60 years later, scientists from the same institution have published a paper in the same journal, but their results suggest that there may be more to the structure of DNA than their predecessors thought.
A burrow is just a hole in the ground, right? Wrong. Different species of mice have very different burrow designs, and
a new study suggests that a mouse’s architectural know-how is written in its DNA: Mice constructed these species-specific burrows even when they had never seen one before.
Researchers examined the burrowing behaviors of two related mouse species. The deer mouse makes a simple burrow, just a short tunnel that leads to a nest. The closely related oldfield mouse puts a little more feng shui in its design, extending the entry tunnel and adding a back door for quick escapes from the nest. To see if the blueprints for these burrow designs were based on instinct, researchers brought the mice into the lab.
Some women always have men on the brain. And some women literally have men in their brains. A new study in PloS ONE found that quite a few female brains contain male DNA. This genetic material presumably passes into a mother while she is pregnant with a male fetus. Although we already knew that fetal cells can enter a mother’s body, until now, it was unknown whether the cells could pass into the brain as well, because the blood brain barrier normally blocks large molecules and foreign substances from entering the brain.
To explore the possibility of brain microchimerism—the presence of genetically distinct cells in a host’s body—researchers examined autopsy specimens from 59 deceased female subjects, who either had no neurological disease or had suffered from Alzheimer’s. The scientists found that 63 percent of the brains contained male cells distributed throughout the organ, and that this microchimerism did not fade away over time: the brain of one 94-year-old woman still contained male cells. And interestingly, the brains of subjects with Alzheimer’s disease were less likely to contain male DNA, and when they did, they generally had less of it than the healthy brains did.
The universe is more massive than it looks. Although it’s invisible to the eye, this extra mass, called dark matter, seems to interact with visible matter through gravity and the weak nuclear force. Some researchers hypothesize that dark matter consists of WIMPs, or weakly interacting massive particles, which form an invisible “sea” through which the Earth passes as our planet travels through space. While these WIMPs would ordinarily fly right through ordinary matter, we might be able to observe the rare occasions when one directly strikes a nucleus.
One big challenge to WIMP detection is proving that a collision was due to a WIMP, and not to another type of fly-by particle. Some projects are dealing with this problem by burying their detectors deep underground where no interfering radiation can reach; some are using the fact that the number of WIMP collisions is expected to change throughout each day and each year, as Earth’s position in the sea of WIMPS changes. (This approach is similar to the Michaelson-Morley experiment, which disproved the existence of luminiferous aether, another invisible “sea” we supposedly orbited through.) Now an interdisciplinary group of physicists and biologists has an idea to take the comparison of daily and annual measurements to the next level.
DNA is a great way to store information—just ask your cells. Its molecules are stable, and billions of base pairs coil neatly into a few microns in a cell nucleus. While it’s easy for a cell to read information from DNA, a cell can’t rewrite new data into its DNA sequence.
But now synthetic biologists at Stanford have managed to pull off that very trick. To do so, they had to abandon the genetic code of ATCG and get a DNA sequence to act like bits—pieces of binary information—in a computer. The memory system uses two enzymes that can cut out and reintegrate a sequence of DNA in a live cell. Crucially, the attachment sites are designed so that the DNA sequence can be flipped every time it is put back in. The sequence oriented one way would represent 1, and its inversion is 0.
As growing numbers of DIY “biohackers” can attest, extracting DNA from cells is an easy process. And you don’t need anything special to do it: various household products, like soap and isopropyl alcohol, have the chemical properties required. For NOVA’s upcoming program “Cracking Your Genetic Code,” PBS has made a short promotional video demonstrating how you can draw your DNA out from a sample of cheek cells, and, with the help of a little food coloring, actually see it yourself.
The three steps are pretty much exactly what scientists do when extracting DNA in the lab. First, you collect cells in salt water, which is similar to buffer solutions used in labs. Then, break them open with soap (in the lab, a detergent like Triton-X), which disturbs the molecules of the cell and nuclear membranes so the DNA can leak out. Lastly, use alcohol to separate the DNA from the salt water: Once in the alcohol, which is less polar than water, the DNA will form clumps and precipitate out, becoming visible as clusters of white strings.
The video is a neat reminder that what happens in labs isn’t magic: it’s just basic chemistry.
In the dreams of crime scene investigators, no doubt, they can feed a piece of hair into a machine and see a reconstruction of what the owner looks like. There’s a hint of that fantasy in the news that Dutch scientists have developed a test intended help police tell from a crime scene DNA sample the color of a suspect’s eyes. This information is gleaned from examining six single nucleotide polymorphisms, small genetic markers that are used in DNA fingerprinting, and could potentially help steer investigations when there are few other leads on a suspect and there is no match in police DNA databases. But the test, which can tell whether someone has blue, brown, or indeterminate (which encompasses green, hazel, grey, etc.) eyes with an average of 94% accuracy, doesn’t seem to have been tested outside of Europe, which raises questions about how well it would work in populations with greater diversity. It’s also a little hard to feature how you could bring this information to bear in a vacuum of other details—you’d want to avoid hauling someone in just because they looked suspicious and have the same eye color as the readout for the perp. At the moment, the test is not accurate enough to be introduced as evidence in court, which could be a bad thing or a good thing…depending on how many Philip K. Dick novels you’ve read.
Image courtesy of wetwebwork / flickr
What’s the News: We’ve long had signs that when it comes to inheritance, DNA isn’t the be-all, end-all. Trees that have the exact same genes but were raised in different greenhouses behave differently. Worms with genes that impart long life can pass on that longevity to their progeny—even if they don’t pass on the genes. Both of these phenomena, we’ve discovered, come from epigenetic changes in tags attached to DNA that control whether genes get expressed.
But every now and then we get a whiff of other possible routes for inheritance, even stranger than that. A new paper in Cell reports that worms whose grandparents had the ability to fight viruses using a fleet of tiny RNA molecules retain these molecules even when they don’t have the genes for them. They can pass these molecules down for more than a hundred generations.