Monthly Archives: November 2012

Public release date: 18-Nov-2012 [ | E-mail | Share ]

Contact: Karen N. Peart karen.peart@yale.edu 203-432-1326 Yale University

The prevailing wisdom has been that every cell in the body contains identical DNA. However, a new study of stem cells derived from the skin has found that genetic variations are widespread in the body's tissues, a finding with profound implications for genetic screening, according to Yale School of Medicine researchers.

Published in the Nov. 18 issue of Nature, the study paves the way for assessing the extent of gene variation, and for better understanding human development and disease.

"We found that humans are made up of a mosaic of cells with different genomes," said lead author Flora Vaccarino, M.D., the Harris Professor of Child Psychiatry at the Yale Child Study Center. "We saw that 30 percent of skin cells harbor copy number variations (CNV), which are segments of DNA that are deleted or duplicated. Previously it was assumed that these variations only occurred in cases of disease, such as cancer. The mosaic that we've seen in the skin could also be found in the blood, in the brain, and in other parts of the human body."

The longstanding belief has been that our cells have the same DNA sequence and this blueprint governs the body's functions. The Yale team's research challenges this dogma. Some scientists have hypothesized that during development, when DNA is copied from mother to daughter cells, there could be deletions, duplications and changes in the sequence of the DNA, and an entire group of genes could be affected. This premise has been incredibly difficult to test, but Vaccarino and colleagues have done so in this new study.

The team used whole genome sequencing to study induced pluripotent stem cells lines (iPS), which are stem cells developed from a mature-differentiated cell. The team grew cells taken from the inner upper arms of two families. The team spent two years characterizing these iPS cell lines and comparing them to the original skin cells.

While observing that the genome of iPS cells closely resembles the genome of skin cells from which they originated, the team could identify several deletions or duplications involving thousands of base pairs of DNA. The team then performed additional experiments to understand the origin of those differences, and showed that at least half of them pre-existed in small fractions of skin cells. These differences were revealed in iPS cells because each iPS line is derived from one, or very few, skin cells. Vaccarino said these iPS lines could act as a magnifying glass to see the mosaic of genomic differences in the body's cells.

"In the skin, this mosaicism is extensive and at least 30 percent of skin cells harbor different deletion or duplication of DNA, each found in a small percentage of cells," said Vaccarino. "The observation of somatic mosaicism has far-reaching consequences for genetic analyses, which currently use only blood samples. When we look at the blood DNA, it's not exactly reflecting the DNA of other tissues such as the brain. There could be mutations that we're missing."

"These findings are shaping our future studies, and we're doing more studies of the developing brains of animals and humans to see if this variation exists there as well," Vaccarino added.

The rest is here:
Skin cells reveal DNA's genetic mosaic

The tiny, all-female bdelloid rotifers have endured the past 80 million years without sex. New research shows that gobbling up foreign DNA from other simple life-forms might be the asexual animal's secret to survival.

In the study, scientists discovered that up to 10 percent of the active genes in microscopic bdelloids comes from bacteria and other organisms like fungi and algae. The finding adds to "the weirdness of an already odd little creature," said Alan Tunnacliffe, a University of Cambridge professor and lead author of the study.

"We don't know how the gene transfer occurs, but it almost certainly involves ingesting DNA in organic debris, which their environments are full of," Tunnacliffe explained in a statement. "Bdelloids will eat anything smaller than their heads!"

Many asexual creatures are thought to be doomed to extinction due to the lack of genetic diversity and build-up of mutations that often come with reproducing from just one parent's DNA. But bdelloids have managed to avoid such pitfalls of asexual life, diversifying into at least 400 species.

One of the critters' more remarkable qualities is their ability to withstand extreme dehydration, which could be, in part, thanks to the alien DNA. The new study found that some of the foreign genes are activated when the bdelloids begin to dry out in their ephemeral aquatic homes. These genes also might be behind powerful antioxidants thought to protect bdelloids from the by-products of drying out.

"These antioxidants have not yet been identified, but we think that some of them result from foreign genes," Tunnacliffe added.

Bdelloids' success could also be attributed to their potent DNA repair mechanisms, which seem to have evolved thanks to a duplicate set of genes, according to research detailed in 2008 in the journal Proceedings of the National Academy of Sciences.

The new findings were detailed in the journal PLoS Genetics Thursday (Nov. 15).

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'Odd Little Creature' Skips Sex and Eats DNA

Posted on November 18, 2012, Sunday

Guanine, adenine, thymine, cytosine Android? The Droid DNA the latest addition to Verizons Droid series may not contain any actual nucleotides (that we know of), but that doesnt make this HTC-made superphone any less of a powerhouse. On the contrary, weve been eyeballing this handset with eager anticipation ever since it first launched in Japan as theJ Butterfly; much like its counterpart from the Land of the Rising Sun, the DNA boasts a jaw-dropping 5-inch,1080p display. But while that may be the headliner-worthy feature, you certainly cant go wrong with a quad-core Snapdragon S4 Pro processor and 2GB of RAM taking charge behind the scenes, along with anImageSensecamera and other top-notch specs.

In certain respects, the Droid DNA is a sneak preview of whats to come in 2013: a wave of high-performance superphones that take advantage of this improved resolution, and offer a long list of other top-notch features. Indeed, thats a future we could all definitely live with, but lets not get too ahead of ourselves; weve got a phone to review, after all. Is the display as tantalizing as it sounds? Will its size be a selling point or a major distraction? Should you waltz into a Verizon store on Black Friday and demand they take your hard-earned $200? Follow us after the break as we focus on the here and now.

HTC may not be the king of the hill in device sales or financials, but 2012 has convinced us that its firmly planted as the champion in smartphone design. The companys had a knack for thinking outside the rectangular box and coming up with cleverly built handsets theSensationseries andTouch Diamondcome to mind but it seems to have cranked the focus up another notch this year. The One series was beautifully crafted and each model therein acted as a brilliant indication of HTCs renewed dedication; without skipping a beat, it was later followed up with the colorful and visually stunningWindows Phone 8X, which has been readily endorsed by Microsoft.

This brief bit of background was added to emphasize one important thing: HTC isnt slacking off with the Droid DNA. Everything about the phone straight down to the Ferrari-inspired edges screams luxury and ensures a comfortable experience. Were just as drawn to its beauty as we were when we first beheld theOne Xwith our own eyes. Its an incredibly sleek and solidly built device that wont leave us worried about durability, since it consists of aluminum on the sides and a soft-touch polycarbonate on the back that is quite similar to the material used on the 8X. (Unfortunately, its also a fingerprint magnet.)Gorilla Glass 2graces the display with the promise of preventing that beautiful screen from getting scuffed.

Currently, the DNA only comes in one color option: black with red accents. These two colors have been HTCs bread and butter for many years, so it comes as no huge shocker that this would be the default choice for, well, Big Red. It also correlates with theBeats Audiocolor scheme, so its a perfect combination for every party involved. The red isnt overbearing and complements the black quite well, accentuating the power button, earpiece, camera and edges (as we mentioned earlier, the grille-like edge design was apparently inspired by Ferrari, and we fully support that decision).

The same folks who were concerned about theGalaxy Note IIsbehemoth size will also have identical reservations for the 5-inch DNA at first, but this particular device isnt looking to compete in the same genre. HTC went out of its way to emphasize that the DNA is a smartphone, not a phablet, and we can definitely attest to that statement. Holding it up to your ear when making a call likely wont inspire the same feelings of awkwardness as the Note II might do, and its much easier to use for one-handed tasks without needing special keyboards or dialpads. In fact, the DNAs form factor reminds us of what youll find on the One X andSamsung Galaxy S III: at 70.5mm (2.78 inches) wide, its only 0.6mm wider than the One X and is actually 0.1mmnarrowerthan the GS3. Boasting a height of 141mm (5.55 inches), its also taller than either phone. At its thickest point, the DNA measures at 9.73mm (0.38 inch), which is a bit thicker than the 8.9mm One X and 8.6mm GS3, but the back gently slopes to meet the 4mm-thick tapered edges. We were expecting the phone to require some sort of adjustment period at first, but we found the DNA to be a completely natural fit in the palm of our hand and it feels great.

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HTC Droid DNA review