Bacterium engineered with DNA in which thymine is replaced by synthetic building block

The genetic information of all living cells is stored in the DNA composed of the four canonical bases adenine (A), cytosine (C), guanine (G) and thymine (T). An international team of researchers has now succeeded in generating a bacterium possessing a DNA in which thymine is replaced by the synthetic building block 5-chlorouracil (c), a substance toxic for other organisms.The project, coordinated by Rupert Mutzel (Institut für Biologie, Freie Universität Berlin) and Philippe Marlière (Heurisko USA Inc.), involved researchers of the French CEA (Commissariat à l'Energie Atomique et aux Energies Alternatives) and of the Katholieke Universiteit Leuven (Belgium). As described in the latest issue of Angewandte Chemie International Edition, the experimental work was based on a unique technology developed by Marlière and Mutzel enabling the directed evolution of organisms under strictly controlled conditions. Large populations of microbial cells are cultured for prolonged periods in the presence of a toxic chemical -- in this case, 5-chlorouracil -- at sublethal levels, thereby selecting for genetic variants capable of tolerating higher concentrations of the toxic substance.
In response to the appearance of such variants in the cell population the concentration of the toxic chemical in the growth medium is increased, thus keeping the selection pressure constant. This automated procedure of long term evolution was applied to adapt genetically engineered Escherichia coli bacteria unable to synthesize the natural nucleobase thymine to grow on increasing concentrations of 5-chlorouracil. After a culture period of about 1000 generations descendants of the original strain were obtained which used 5-chlorouracil as complete substitute for thymine. Subsequent genome analysis revealed numerous mutations in the DNA of the adapted bacteria. The contribution of these mutations to the adaptation of the cells towards the halogenated base will be the subject of follow-up studies.
Besides the obvious interest of this radical change in the chemistry of living systems for basic research the scientists consider the outcome of their work also to be of importance for "xenobiology," a branch of synthetic biology. This young area of the life sciences aims at the generation of new organisms not found in nature harboring metabolic traits optimized for alternative modes of energy production or for the synthesis of high value chemicals. Like GMOs, such organisms are seen as a potential threat for natural ecosystems when released from their laboratory confinements, either through direct competition with wild type organisms or through diffusion of their "synthetic" DNA.
Scientists have recognized that physical containment cannot in every single case prevent engineered live forms from reaching natural habitats, in the same way as radioactive isotopes can leak into the surroundings of a nuclear power plant. However, synthetic organisms like those evolved by Marlière and Mutzel and their collaborators which depend on the availability of substances for their proliferation not found in nature or which incorporate non-natural building blocks in their genetic material could neither compete nor exchange genetic messages with wild type organisms, but would die in the absence of the xenobioticM I B S I T B T

A man from Alabama first to receive Stem Cell Therapy

A man from Alabama has become the first person in the United States to receive a highly-debated embryonic stem cell transplant. Researchers are hoping the technology will be a game changer for those with debilitating spinal cord injuries.

TJ Atchinson hopes he's living the dream of Superman Christopher Reeve -- to become the first human to receive embryonic stem cell therapy. Atchinson was paralyzed following a devastating car accident."I realized I couldn't feel from (the top) down," Atchinson said. "When I got to the hospital, they said I would never walk again."

Atchinson was still accepting the news when doctors told him he'd be a great candidate for the stem cell therapy. Though he was injured just a few days before getting the offer, his body was strong and his will was even stronger. Atchinson agreed to be a laboratory of hope -- the first human with a spinal cord injury to test human embryonic stem cells. 

Doctors began the procedure by opening his wound, then guiding a needle into his body. Doctors injected Atchinson with two million all-purpose stem cells that they hope will transform into new nerve cells and attach to muscles, refiring his central nervous system.
In the laboratory, they've used embryonic stem cells to repair the broken spinal cords of small animals that walked again. The stem cells have the potential to produce unlimited quantities of any type of cell. Atchinson's mother says she knows that people oppose the therapy on religious grounds, but thinks they're unreasonable."There are some people who are against it, but until they've been put in the position I don't think they should judge anybody," Atchinson's mother told ABC News. Atchinson says his role in the procedure was to prove it was safe, but he says he can already start to feel it working. "Right now, I can feel that," Atchinson said while pulling at hair on his leg.

Six months after the procedure, Atchinson says he can feel a sense of weight when he places heavy items onto his lap. As he rubs his leg, Atchinson says, "I can tell that...I can feel that there's something there." Atchinson is holding out hope that he can one day run again like he once did before his accident.

Source: ABC7News, San Francisco, CA

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India's Top 50 Engineering Colleges 2011

Heavily dominated by public institutions, the top-50 listing is a roll call of excellence India's top 50 engineering institutions 2011

Ranking the top colleges is a very difficult task. While it is relatively easy to create clusters of colleges, it is differentiating within clusters that became the most difficult exercise. So for the first time in the country we have used balanced scorecard methodology to arrive at the ranking of the top 50 colleges. Ranking methodology: We scanned the last five year rankings of about 241 colleges and normalised their ranks, by assigning differential weights to subjective and objective ranking. Such a process is used to develop clusters of institutions. The research standing of individual institutions were further used to refine the clusters and remove the odd men out. Individual clusters were ranked serially. In each of these clusters the differences in cut-off marks, wherever possible (like in case of IITs and AIEEE institutes and some States) were used to arrive at individual ranks. Heavily dominated by public institutions, the top-50 listing is a roll call of excellence India's top 50 engineering institutions 2011

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Mahantesh.I.B
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343