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Friday, 27 March 2009

Genetic successes, 03, 2009

Today:

  1. Scientists explore new window on the origins of life
  2. Human evolution kicks into high gear
  3. Gene therapy shows promise as weapon against HIV
  4. Gene caps may turn viruses cancerous
A great one! I urge you to read articles 2 and 4, both are extremely interesting. The second suggest that mankind is not only still evolving, but evolving faster and faster. With some more interesting implications. And the last article is about an exciting new way to monitor cancer development. The other articles are also quite intriguing.

Scientists explore new window on the origins of life

February 12th, 2009

All living cells on the planet go through the process of division in order to survive and thrive. Cell division, or binary fission, allows one cell to split down the middle to become two cells.

In the work published in Nature, Newcastle University scientists have found that under some conditions, including treatment with antibiotics, common bacteria switch to a whole new way of increasing in number that may have been used by the first cells to evolve on the planet.

Bacteria have been around for more than two billion years and now occupy every corner of the environment. The secret of their success seems to be their tough outer skin or cell wall. This protective barrier can also be a weakness and is the target for many of our best antibiotics, including penicillin.

The Newcastle University scientists have found out how to induce a bacterium to live without a wall. These fragile cells called L-forms, have a wobbly shape with only a thin surface membrane holding them together. What has surprised scientists is that the bacteria seem to be pre-prepared to make this switch to life without a wall.

Now that L-forms can be studied more closely the Newcastle University team led by Professor Jeff Errington has found the drug-resistant bacteria are multiplying in a way which has never been seen before. Instead of dividing in two, the L-form bacterium pulsates and then ‘squirts out babies’, sometimes as many as five new bacteria each time. This was completely unexpected.

“What we have uncovered seems to be a primitive mode of growth probably used by the very earliest cells on the planet,” says Professor Errington, Director of the Institute for Cell and Molecular Biosciences at Newcastle University. source

My comment: Why this is cool? Well because this is as said a completely new way of multiplying and which shows something important-that even if we manage to target the cell "walls" and destroy them, then the bacteria actually multiply even faster. That could be a very unpleasant side-effect from a good antibiotic and should be carefully considered. In any case, this is good research.

Human evolution kicks into high gear

By Kathleen McAuliffe, Feb. 10, 2009

For decades the consensus view — among the public as well as the world’s preeminent biologists—has been that human evolution is over since Homo sapiens emerged 50,000 years ago.

So to suggest that humans have undergone an evolutionary makeover from Stone Age times to the present is nothing short of blasphemous. Yet a team of researchers has done just that.

They find an abundance of recent adaptive mutations etched in the human genome; even more shocking, these mutations seem to be piling up faster and ever faster, like an avalanche. Over the past 10,000 years, their data show, human evolution has occurred a hundred times more quickly than in any other period in our species’ history.

The new genetic adaptations, some 2,000 in total, are not limited to the well-recognized differences among ethnic groups in superficial traits such as skin and eye color. The mutations relate to the brain, the digestive system, life span, immunity to pathogens, sperm production and bones — in short, virtually every aspect of our functioning.

Many of these DNA variants are unique to their continent of origin, with provocative implications. “It is likely that human races are evolving away from each other,” says University of Utah anthropologist Henry Harpending.

Harpending theorizes that the attitudes and customs that distinguish today’s humans from those of the past may be more than just cultural, as historians have widely assumed. “We aren’t the same as people even a thousand or two thousand years ago,” he says. “Almost every trait you look at is under strong genetic influence.”

Not surprisingly, the new findings have raised hackles. Some scientists are alarmed by claims of ethnic differences in temperament and intelligence, fearing that they will inflame racial sensitivities. Other researchers point to limitations in the data. Yet even skeptics now admit that some human traits, at least, are evolving rapidly, challenging yesterday’s hallowed beliefs.

Hawks points out: In Europeans, the cheekbones slant backward, the eye sockets are shaped like aviator glasses, and the nose bridge is high. Asians have cheekbones facing more forward, very round orbits, and a very low nose bridge. Australians have thicker skulls and the biggest teeth, on average, of any population today.

“It beats me how leading biologists could look at the fossil record and conclude that human evolution came to a standstill 50,000 years ago,” Hawks says.

Thanks to stunning advances in sequencing and deciphering DNA in recent years, scientists had begun uncovering, one by one, genes that boost evolutionary fitness. These variants, which emerged after the Stone Age, seemed to help populations better combat infectious organisms, survive frigid temperatures, or otherwise adapt to local conditions. And they were popping up with surprising frequency.

“We realized, gee, there’s a lot more people on the planet in recent times,” Hawks recalls. “In a large population you don’t have to wait so long for the rare mutation that boosts brain function or does something else desirable.”

The logic behind the notion was undeniably simple, but at first glance it seemed counterintuitive. The genomes of any two individuals on the planet are more than 99.5 percent the same. Put another way, less than 0.5 percent of our DNA varies across the globe. That is often taken to mean that we have not evolved much recently, Cochran says, “but keep in mind that the human and chimp genomes differ by only about 1 to 2 percent—and nobody would call that a minor difference. ” source

My comment: Awesome! And I very much hope this wont cause a burst of racism, since it's not the point of the research. The point is that we're changing, and we're accumulating changes by our experiences and when we breed, we pass those changes. Obviously people in similar environment, like those in one country, one tribe, one family, will have more similar changes. I don't see that racism, but like identity. We are who we are, we shouldn't hide this in desperate anti-racism, the very idea of racism should have disappeared by now, because we know so much more about each other. No other races is more or less important than your own, but that couldn't and shouldn't mean that we're all the same. We are not. We are different and that's nothing to be ashamed from. Quite the opposite-exactly our difference is our best chance of survival and progress. I'm so happy by this research!

Gene therapy shows promise as weapon against HIV

February 17th, 2009 By Enrique Rivero

(PhysOrg.com) -- A new UCLA AIDS Institute study has found that gene therapy can be developed as a safe and active technique to combat HIV.

Though modest, the results do show some promise that gene therapy can be developed as a potentially effective treatment for HIV, said lead investigator Dr. Ronald Mitsuyasu, professor at UCLA.

This was the first randomized, double-blind, placebo-controlled gene-transfer clinical trial and involved 74 HIV-positive adults.

The patients received their own blood stem cells, either untreated or modified to carry a molecule called OZ1, which prevents viral replication by targeting a key HIV gene. OZ1 was safe, causing no adverse effects over the course of the 100-week trial.

At the primary end-point, the difference in viral load between the OZ1 and placebo group at weeks seven and eight, after they had stopped HAART treatment, was not statistically significant. But other viral parameters did demonstrate better HIV suppression and improvement in the counts of CD4+ lymphocytes — the cell population that is depleted by HIV.

The technique still needs to be developed further and perfected, because the persistence of the treated stem cells is too short, Mitsuyasu said. source
My comment: Although it surely sounds promising, I think this article is little premature. The treatment showed only little progress in the counts of the lymphocytes, that's only the beginning. Anyway, it's great to see the many applications of stem cells in absolutely non-invasive procedures.

Gene caps may turn viruses cancerous

CANCER-CAUSING viruses undergo genetic changes as their host cells become malignant. The finding could allow doctors to predict when people infected with a virus will develop cancer, and possibly points to new treatments.

It is already known that cells turning cancerous accumulate chemical "caps", called methyl groups, on crucial tumour-suppressor genes. These caps silence the genes, often speeding up the onset of cancer.

To investigate, Manel Esteller and his colleagues totted up the methylations on the entire genome of various types of cancer-causing virus. These included strains 16 and 18 of the human papilloma virus (HPV), which can cause cervical cancer, and hepatitis B virus, which can lead to liver tumours. They also looked for methylations in Epstein-Barr virus, which is associated with some types of lymphoma.

For each virus, the team obtained three sets of samples: from people who were carriers but had no cancer symptoms, from those who had precancerous lesions, and from people with full-blown cancer.

In all four viruses, the degree of methylation correlated with disease progression. One gene found in HPV-16, for example, was not methylated in any of 10 asymptomatic carriers, but was in 21 of 60 people with precancerous lesions, and 16 of 17 with cervical cancer (Genome Research, DOI: 10.1101/gr.083550.108).

When you start to get methylation on viral genes, you start to get cancer developing

He suggests that doctors could start monitoring the methylation status of these viruses in order to predict when the infection is progressing towards cancer.

Siavash Kurdistani, a cancer biologist at the University of California, Los Angeles, commends the work but points out that it doesn't show whether viral methylation triggers cancer or is merely a by-product of the methlyation that occurs in already cancerous cells.

If methylation plays a causative role, demethylating agents - already part of the chemotherapy regime for some other cancers - could be used against virally induced tumours as well, says Esteller. source

My comment: Obviously a very exciting research. It actually gives a way to measure the progress of the tumor and take action when it's needed, not before that. If you remember, there was a reasearch claiming that big part of the tumors disappear from themselves before getting malignant and spreading over. If we could monitor the methilation, maybe we could have a good way to find out when to start treatment-before it's too late, but also, before it's too early!

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