Amazing Science

Scientists have deciphered molecular-level details of the complex choreography by which intricate cellular proteins recognize and bind to DNA to start the DNA replication process. The research may point to ways to block unwanted cell division.

Chloroplasts, the plant cell’s green solar power generators, were once living beings in their own right. This changed about one billion years ago, when they were swallowed up but not digested by larger cells. Since then, they have lost much of their autonomy. As time went on, most of their genetic information found its way into the cell nucleus; today, chloroplasts would no longer be able to live outside their host cell.

Since the transfer of genes into the cell nucleus is an extremely slow evolutionary process, which has taken nature millions of years, it has not been possible to investigate the underlying mechanism to date. However, researchers have now managed to fast-forward this gene transfer in the laboratory. Because the cells were subjected to high selection pressure, the transference of genes from the chloroplasts into the nucleus became essential for survival, so that it could be made readily visible. It was found that the transfer takes place without the involvement of RNA and that the DNA apparently jumps directly from the cell’s chloroplasts into its nucleus.

Twenty billion pieces of DNA in 100 small fish have opened the eyes of biologists studying evolution. After combining new technologies, researchers now know many of the genomic regions that allowed an ocean-dwelling fish to adapt to fresh water in several independently evolved populations.

All cattle are descended from as few as 80 animals that were domesticated from wild ox in the Near East some 10,500 years ago, according to a new genetic study. An international team of scientists from the CNRS and National Museum of Natural History in France, the University of Mainz in Germany, and UCL in the UK were able to conduct the study by first extracting DNA from the bones of domestic cattle excavated in Iranian archaeological sites. These sites date to not long after the invention of farming and are in the region where cattle were first domesticated.

The team examined how small differences in the DNA sequences of those ancient cattle, as well as cattle living today, could have arisen given different population histories.

Sangamo is using zinc finger nuclease-mediated editing technology (ZNF) to replicate the naturally occurring human mutation in CCR5, a chemokine receptor that renders individuals largely resistant to infection with the most common strain of HIV. Sangamo’s approach comprises removal of CD4+ T-cells from the blood of immunologic non-responders HIV-infected subjects who are currently on highly active antiretroviral therapy (HAART), having undetectable levels of the virus but a suboptimal CD4+ T-cell counts. These CD4+ T-cells are then treated with Sangamo’s ZFNs that modify the DNA sequence encoding the CCR5 gene. The process indeed generates CCR5-modified, autologous T-cells (SB-728-T), which are then infused back into HIV/AIDS patients. The data obtained are actually stunning. The approach so far has proven to be safe, as infusions of SB-728-T are well tolerated. The CCR5-modified cells successfully engrafted in all subjects studied and resulted in a durable improvement in total CD4+ T-cell counts in five of six of the subjects analyzed. Five of the six subjects exhibited sustained improvements in their CD4:CD8 T-cell ratio, which is an indicator of immunologic health. The ZFN-CCR5-modified cells exhibited normal T-cell growth kinetics and trafficking and underwent selective expansion in the gut mucosa, a major reservoir of virus in the body, suggesting that the cells were resistant to HIV infection.

http://tinyurl.com/8y99ors

Nature also selected ZNF to be the method of the year for 2011:

http://www.youtube.com/watch?v=zDkUFzZoQAs

One of the hallmarks of cancer cells is that certain regions of their DNA tend to get duplicated many times, while others are deleted. Often those genetic alterations help the cells become more malignant — making them better able to grow and spread throughout the body.

Now, a team of MIT and Harvard University researchers has found that the three-dimensional structure of the cell’s genetic material, or genome, plays a large role in determining which sections of DNA are most likely to be altered in cancerous cells.

http://tinyurl.com/8yheu6u

LifeNaut is a free online service (and experiment) for personal data storage and avatar interactivity. It allows people to build a rich personal profile that preserves their essential, unique qualities as ‘mindfiles.’ You can also store your DNA.

Mindfiles are database files with uploaded digital information (videos, pictures, documents, and audio recordings) about a person’s unique characteristics (such as mannerisms, attitudes, values, and beliefs). Future AI programs will use a mindfile and a person’s DNA to create a digital clone of that person that can interact with future family members and others.

http://www.kurzweilai.net/welcome-to-your-future-clone

Fifty years ago, scientists uncovered a microbe capable of withstanding radiation in canned meat that had been bombarded with gamma rays. Named Deinococcus radiodurans--or "strange berry that withstands radiation" --the microorganism can survive doses of radiation up to 500 times that which would kill a human. These doses shatter D. radiodurans' DNA--just as they would in a human--but the microbe can repair its broken DNA and spring back to life within hours, depending on the dose. Researchers in France have now finally determined how the most durable of extremophiles manages this trick. "We have discovered the mechanism by which a clinically dead cell resurrects back to life," explains Miroslav Radman of INSERM, France's public biomedical research institution. "This extreme radiation resistance is but a by-product of its selection for resistance to desiccation."

Researchers from the University of North Carolina at Chapel Hill have helped identify a new DNA entity in mammalian cells and provided evidence that their generation leaves behind deletions in different locations of the cells’ genetic program, or genome. The researchers discovered these new entities in mouse tissues and brain cells and in human cell lines. Unlike previously identified large DNA circles, these circles of unique non-repetitive microDNA sequences are in the coding and control regions of genetic information.

The Breast Cancer Genome Guided Therapy Study (BEAUTY Project) will help physicians tailor chemotherapy to breast cancer patients based on their individual genomes and the genomes of their tumors. Mayo Clinic researchers will obtain three whole genome sequences: one from the patients' healthy cells before treatment, and two tumor genomes – one before chemotherapy and one after. Patients will be paired with mouse "avatars" that will help physicians identify the best treatment for each person.

Additional read: DNA of 50 breast cancer patients decoded (http://tinyurl.com/7upzl3z)

All the Proteus patients studied shared the same single-base mutation in a gene called AKT1. The same glitch appeared in 26 of 29 patients diagnosed with Proteus disease and in 1% to about 50% of the DNA in positive cell samples investigated. To bolster the case that the mutation was causing disease, the scientists also showed that the AKT protein is overactive in the abnormal cells. The AKT1 gene, which is part of a cell-growth pathway, has also been found to be mutated in some cancers.

Identifying Cancer Mutations - Determining the underlying cause of disease is a daunting task. In a 1994 Time magazine interview, Francis Collins, now director of the National Institutes of Health, said that locating a gene from scratch was like "trying to find a burned-out light bulb in a house located somewhere between the East and West coasts without knowing the state, much less the town or street the house is on." With its 3 billion base pairs distributed over 23 paired chromosomes, the human genome is an epic map to navigate. Nevertheless, an international effort to map the human genome at the individual DNA base pair level—the Human Genome Project—was initiated in 1990. The effort cost more than $2.7 billion, involved 20 research institutes and culminated in 2003 with the publication of the completed DNA sequence of the human genome.

http://tinyurl.com/6pp4l6j

Long before Watson and Crick famously uncovered the structure of DNA in 1953, people envisioned with both horror and hope a day when babies could be custom designed — free of inherited disease, yet equipped with superior genes for good looks, intelligence, athleticism, and more. Now the beginnings of the day of designer babies have finally come.

http://tinyurl.com/baeqm9

Scientists have discovered the molecular pathway by which maternally inherited deafness appears to occur: Mitochondrial DNA mutations trigger a signaling cascade, resulting in programmed cell death.

http://tinyurl.com/86v4blp