DNA Evidence Can Be Fabricated

Scientists in Israel have demonstrated that it is possible to fabricate DNA evidence, undermining the credibility of what has been considered the gold standard of proof in criminal cases.

The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. They also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person.

"You can just engineer a crime scene," said Dan Frumkin, lead author of the paper, which has been published by the journal Forensic Science International: Genetics. "Any biology undergraduate could perform this."

Frumkin is a founder of Nucleix, a company based in Tel Aviv that has developed a test to distinguish real DNA samples from fake ones that it hopes to sell to forensics laboratories.

The planting of fabricated DNA evidence at a crime scene is only one implication of the findings. A potential invasion of personal privacy is another.

Using some of the same techniques, it may be possible to scavenge anyone’s DNA from a discarded drinking cup or cigarette butt and turn it into a saliva sample that could be submitted to a genetic testing company that measures ancestry or the risk of getting various diseases.

Tania Simoncelli, science adviser to the American Civil Liberties Union, said the findings were worrisome.

"DNA is a lot easier to plant at a crime scene than fingerprints," she said. "We’re creating a criminal justice system that is increasingly relying on this technology."

John M. Butler, leader of the human identity testing project at the National Institute of Standards and Technology, said he was "impressed at how well they were able to fabricate the fake DNA profiles." However, he added, "I think your average criminal wouldn’t be able to do something like that."

The scientists fabricated DNA samples two ways. One required a real, if tiny, DNA sample, perhaps from a strand of hair or drinking cup. They amplified the tiny sample into a large quantity of DNA using a standard technique called whole genome amplification.

Of course, a drinking cup or piece of hair might itself be left at a crime scene to frame someone, but blood may be more believable.

The authors of the paper took blood from a woman and centrifuged it to remove the white cells, which contain DNA. To the remaining red cells they added DNA that had been amplified from a man’s hair.

Since red cells do not contain DNA, all of the genetic material in the blood sample was from the man. The authors sent it to a leading American forensics laboratory, which analyzed it as if it were a normal sample of a man’s blood.

The other technique relied on DNA profiles, stored in law enforcement databases as a series of numbers and letters corresponding to variations at 13 spots in a person’s genome.

From a pooled sample of many people’s DNA, the scientists cloned tiny DNA snippets representing the common variants at each spot, creating a library of such snippets. To prepare a DNA sample matching any profile, they just mixed the proper snippets together. They said that a library of 425 different DNA snippets would be enough to cover every conceivable profile.

Nucleix’s test to tell if a sample has been fabricated relies on the fact that amplified DNA — which would be used in either deception — is not methylated, meaning it lacks certain molecules that are attached to the DNA at specific points, usually to inactivate genes.

Posted in: NY Times, Science, 17 Aug 2009,

Chipping In

BRAIN CHIP FOR MEMORY REPAIR CLOSES IN ON LIVE TESTS

Supplementing the human brain with computer power has been a staple of science fiction. But in fact, researchers have taken several steps in melding minds with machines, and this spring a team from the University of Southern California may replace damaged brain tissue in rats with a neural prosthesis.
For the past few years, researchers have demonstrated the ability to translate another creature’s thoughts into action. In 2000 neurologist Miguel Nicolelis of Duke University wired a monkey with electrodes so that its thoughts could control a robotic arm. Brain-machine interfaces developed by Niels Birbaumer, a neuroscientist at the University of Tübingen in Germany, already help some paralyzed patients move a computer cursor with their brain waves to select letters for writing a message.
Theodore W. Berger and his U.S.C. colleagues have developed the first brain-machine interface to communicate back to the brain. Last January they used a silicon chip to mimic biological neurons in tissue slices of rat hippocampus, the hub for memory sorting and storage. The chip replaced a surgically removed section of the hippocampus and restored function by processing incoming neural signals into appropriate output with 90 percent accuracy.
The biomedical engineers had been on the verge of testing a chip in hippocampus slices for several years, but roadblocks slowed work. Existing electrode array technology would not function well in tissue slices, forcing the researchers to construct their own. Cutting the hippocampus slices just right to keep the neural pathway intact was also difficult.
Because building the one-millimeter square chip costs tens of thousands of dollars and takes several months, the planned spring test will actually rely on a model of that chip—specifically a larger, reprogramable device linked to a computer called a field programmable gate array (FPGA). The FPGA will allow investigators to easily test and modify their new mathematical model of neural communication for living rats before committing it to a chip. Sam Deadwyler, a professor of physiology and pharmacology at Wake Forest University and a collaborator in the study, has demonstrated that stimulating the hippocampus of living rats with a certain pattern of activity can increase performance on a memory task, such as recalling which lever will dispense water. In a few months he will use the FPGA mathematical model to predict hippocampal activity. If the model is correct, the artificial implant should restore memory for such tasks in rats with drug-induced amnesia.
For more complicated animal models, U.S.C. physicist Armand Tanguay suggests a multichip module to facilitate the transition. Light beams would transmit signals between neuron units on multiple chip layers. Unlike wires, light beams pass directly through one another without interference, allowing for many more interconnections. The result: a web of light between silicon chips mimicking a dense neural network.
“Many challenges will be encountered as the researchers move from in vitro to in vivo studies in the rat,” says GracePeng, a program director at the National Institutes of Health’s Division of Discovery Science and Technology. In fact, the team is not quite sure what to expect once it goes to live animals. Avoiding rejection by the immune system might mean anchoring cell adhesion molecules to the chip so that the surface of the implant looks like tissue, says U.S.C. chemist Mark Thompson. Neural plasticity, or the brain’s ability to reorganize its connections, could also pose a problem by preventing the formation of stable connections between the neurons and chip. “In other application areas such as motor control or perception, plasticity, and adaptability of the brain usually facilitate the effects of artificial interfaces,” Peng notes optimistically.
One other possible concern, if such implants make it to human testing: Might bypassing damaged neurons in the hippocampus also bypass connections with other areas of the brain that filter what we remember? In other words, would the brain become unable to purge memories? If so, that would make the implant a truly unforgettable device.

NEURON LANGUAGE
To engineer the brain chip, Theodore W. Berger of the University of Southern California first investigated the nuts and bolts of neuron communication. For more than two decades, he probed neurons in rat hippocampal tissue with electrical stimulation patterns, recorded their responses and created a comprehensive database of neuron behavior. His U.S.C. colleagues Vasilis Marmarelis and John Granacki developed mathematical equations to model neuron behavior and transformed the equations into hardware language. If animal trials are successful, the team’s first human implant will actually use a model of monkey brain activity because researchers cannot safely record activity from humans to develop a human-specific model. Though not ideal, a monkey implant might work well enough, the researchers speculate, because the programmable chip could adapt to human thought or the brain could learn to use the chip as it does with cochlear implants in associating garbled noises with words.



Collected By:
Vikas Y.S.R VII sem

Source:
SCIENTIFIC AMERICAN, INC.

Answer for immunology crossword

BITS AND PEICES

- Katyayini. V sem

Are you in a state when everything seems to be falling apart in your life??? You do not like anybody in your class. The moment you and your brother meet you fight most disgracefully. You look in the mirror and realise that your nose is too long. And you are getting acne of alll sizes on your faces. in short unpleasent things are happening and you just cannot cope...

Well, meet someone who is literally, physically falling apart and still coping...and still coping agaist the toughest of all odds. Meet B.P.Crow, who lives in a lush Flame-of-the-Forest trees opposite my balcony. B.P is not for Blood Pressure but for Bits and Pices. Here is a crow who seems to be made up ofbits and pices that keep falling off, yet B.P.Crow survives and seems happy about it....

To begin with B.P.Crow lost all the toes and claws of one leg when he pearched on the electric transformer a year ago. Next he lost the stump of the leg on which he used to lean, in a violent fight with a raven twice his size, which is why he sits on his belly all the time. When he tries standing, he topples down, and to retain his balance, he has to push his beak on the ground and has to lever himself up His head does not have that smooth, back-combed look all crows have. The few feathers he has stick out in all directions as if someone had crudely glued them on him.

And then there was a day when he got entangled in a ball of plastic wire. By the time a couple of urchins extracted him, which he resisted with all his might, he lost most of his tail. That was also when his voice changed. So when he caws, it sounds like he is being strangled, startling other crows who stare at him in horror. And then came his escape from the vicious tomcat who stalked him one rainy night. As his lone leg couldn't lift his body fast enough, his eye took the swipe from the cat's sharp claws. Not that B.P.Crow's spirits were dampened in any way. His lone eye now gleams with all the inquisitiveness typical of his species.

Now we should come to his beak. Till last week he had a beak which should have been on an vulture. The upper half stuck out a good centimeter longer and was viciously carved at the tip. Of course such a beak is a graet asset in fights but eating is tough, for he had to cock his head sideways to get food into his mouth, and he couldn't hold onto harder food like rotis to break them up, for how could he balance himself if his only leg was used up for that????

And then last week, B.P.Crow vanished. I went down with a basket to see if he was lying down wounded somewhere. But there was no sign of him and i assumed the inevitable had happened. After all, it is amazing, that in a competitive world of crows, with all his disabilities , with no one to protect him, he had somehow survived this long. He undoubtedly had courage, which many of us humans don't have.

And suddenly this morning he reappeared. And he no longer looked like a crow. I had thought it was impossible for B.P.Crow to look more battered and moth eaten than he already was, yet he had managed to become worse!!! That tough vulture beak had somehow broken half way up and now he had a longer lower and a half upper beak. He came flapping in a lopsided way, at the milk soaked bread i hurriedly kept for him on the window ledge and fell headlong into the food. He angrily protested when i tried to help him out. But he now ate digging his lower beak into the food and tilting his head backwarda to let it all go in. All the feathers on his back were gone now. And one wing was clearly broken, it sat on him folded like a rag. But clearly the spirit was not broken. His lone eye shone like a star.

So inspired was i by B.P.Crow's surviving skills that i went back to the mirror to replace my sda , grumpy face with a determinedly smiling one. I then looked at B.P.Crow again out of the window, and this time my smile became a laugh of admiration. Do you know why????

Because in that broken beak, B.P.Crow was now holding a twig lightly. He was building a nest.....!!!!!

THOUGHTS

Poornima V sem

He was poughing on with what he taught,
Not sparing a glance at the restless lot.
Only the nerds were swallowin in,
The rest were of the idea "concentration is sin".....

I looked around and thought with a smile,
The teacher must definitely be senile,
For the whole class was mentally at a pause,
And yet he was fighting a lost cause....

A question I asked. an answer I sought,
Why this torture is what i thought,
Then came the answer, a flash of lightening,
This is one of the processes of engineering......!!!!