Proteins slither around DNA helices.

There are a variety of proteins and enzymes that act at specific spots on DNA.  For example, there are a whole assortment of proteins that recognize the promoter regions in front of genes.  There are also enzymes involved in replication and repair.  How do these proteins get to the right site on the DNA?

It has been known for some time that these proteins must slide along the DNA strand in some manner.  The proteins find their intended targets much too quickly for them to simply be diffusing around the cell and randomly encountering sites along the DNA.  In 2006, a team of Harvard scientists led by Sunney Xie showed that the proteins are in direct contact with the DNA.  The question is, were the proteins sliding down parallel to the DNA strands, or were they actually coiling along the helix?

This problem was solved by Sunney Xie, in collaboration with scientists from Harvard University, the Indian Institute of Science and Brookhaven National Laboratory.  His team used a fluorescent dye to tag individual protein molecules and then used a fluorescence microscope to observe those proteins as they found and bound to their DNA targets.  The scientists could not actually watch the path of the proteins, but they could measure the speed of the interactions.

If the molecules had been sliding straight down parallel to the DNA strands, they would have moved faster than if they curved around the helix.  As it turns out, the proteins slide around the DNA like on a spiral staircase.

Suddenly, it seems like a lot more fun to be a DNA-binding protein molecule!

Flesh eating Petunias?

There are some plants that are known to be carnivorous.  They make their living by trapping and digesting small insects.  The most notable of these are the Venus Flytrap, sundews and pitcher plants.  However, scientists from the Royal Botanic Gardens, Kew and the Natural History Museum think that there isn’t a sharp dividing line between carnivorous and non-carnivorous plants.

Many plants absorb nutrients from the breakdown products of animals through their roots.  Petunias and some other plants have sticky hairs in which insects get trapped.  These plants don’t actively digest the insects but merely allow the trapped insects to die and decompose.  If the remains of the insects fall nearby, the nutrients are available to be absorbed through the plants’ roots.  Are these plants facilitating the accumulation of nutrients beneath them by catching insects?  Mark Chase, Keeper of the Jodrell Laboratory at the Royal Botanic Gardens, believes so:

“many commonly grown plants may turn out to be cryptic carnivores, at least by absorbing through their roots the breakdown products of the animals that they ensnare.”

Suddenly those petunias don’t look so innocent, do they?

Photo of a petunia, by Elena Chochkova, August, 2009

Extrasolar planet directly observed

An extrasolar (from outside our solar system) planet-like object, either a true planet or a brown dwarf, has been directly observed. The object, named GJ 758 B due to its orbit around the star GJ 758, is about ten to forty times the size of Jupiter and about as far from its star as Neptune is from ours.

The first extrasolar planet was found in 1992. Since then, more than 400 such planets have been found. Most have been inferred by measuring the stars’ radial velocity rather than by direct imaging. This technique uses Doppler spectroscopy.

Radial velocity is simply the velocity either directly toward or away from an observer. It can be measured by using the Doppler effect, the red or blue shift of the stars’ light as it departs or approaches the earth respectively. If a star is orbiting in our plane of sight (directly toward and away from us), the star’s emission spectrum will regularly be shifted blue or red as it goes around. The presence of a planet affects the orbit of its star and thus affects that Doppler shift.

In contrast, GJ 758 B was directly observed. Cosmologists did this by using the High Contrast Coronagraphic Imager with Adaptive Optics (HiCIAO) to subtract out the brighter light of its star. This imager is part of the new Subaru Telescope, a planet-hunting telescope based in Hawaii.

This new technique for finding extrasolar planets might usher in a new era of finding planets. Perhaps one of them will even support life!

Vaccine effectiveness compromised by OTC drugs

Vaccine effectiveness appears to be diminished by some common over-the-counter (OTC) drugs.

Cyclooxygenase or COX enzymes (notably COX-1 and COX-2) are part of a chain reaction resulting in inflammation. Inflammation is a normal bodily reaction to injury or invasion by parasites.

Certain OTC drugs, collectively called Non-steroidal anti-inflammatory drugs (NSAIDs), have the affect of decreasing inflammation by blocking COX-1. These drugs include aspirin, ibuprofen and naproxen. Acetominophen, a different type of OTC analgesic, also inhibits the COX pathway.

Now it appears that using these drugs regularly can decrease the effectiveness of a variety of vaccines. Is this because inflammation is a necessary part of developing immunity?

Charles Brown of the University of Missouri’s studies indicate that this may be so. So far, the tests have only been conducted in animals. If the same result is found in humans, Brown suggests that people avoid COX-1 inhibitors for a few weeks before and after receiving a vaccine.

Cheetah legs can make people go faster

Update August 2012: 
Oscar Pistorius was indeed allowed to participate in the 2012 London Olympics. He made it to the semi-finals in the men's 400 meter and ran the anchor leg in the men's 4 x 400 meter relay.
  
You let a double amputee beat you in a foot race?

If the amputee in question is Oscar Pistorius using his 'Cheetah legs', you most likely did!

Oscar Pistorius was born in South Africa in 1986 with a congenital absence of both fibulas. As a result, he had both his legs amputated when he was 11 months old. Nevertheless, he excelled at a variety of sports, switching to running after shattering his knee in rugby. He won gold and bronze at the 2004 Paralympic games, and set his sights on the Beijing Olympic games.

Unfortunately for him, in 2007, the International Association of Athletics Federations (IAAF) passed a regulation banning the use of prosthetics, stating that they gave their users an unfair advantage. They based this decision in part on a study by Gert-Peter Brüggemann. Pistorius appealed this decision, and it was later reversed by the Court of Arbitration for Sport. The South African Olympic Committee allowed him to try out for the 2008 team. He did not qualify. Instead, he returned to the Paralmpics that year, winning two golds.

The question is: was the IAAF right or wrong in assuming that prosthetics can give athletes an advantage?

Peter Weyand of Southern Methodist University and Matthew Bundle of the University of Wyoming published a study stating that Pistorius would indeed have an advantage over runners with intact legs. The difference comes partly from the decreased weight of his legs, the cheetah legs he uses allows him to reposition his legs much more quickly than the heavier flesh and blood limbs his competitor’s use. By one estimate, he can reposition his legs at least 15% more rapidly. This can be a huge advantage in a sport that is measured in centiseconds. In addition, the lightweight springs on the cheetahs reduce the amount of muscle force required to half that of intact limbs. This confirmed the results found earlier by Gert-Peter Brüggemann.

It is unclear how this will affect Pistorius's chances to compete in 2112. If he is allowed to compete, will there be a rash of athletes converting their lower limbs to artificial ones? And we thought drug use was problematic!

Photo of Oscar Pistorius, taken by Elvar Pálsson in Kópavogur, Iceland, 7/8/2007.

Why get a fever?

The immune system is incredibly complicated. Any discussion of how it works can be derailed into myriad asides and explanations. Nonetheless, I shall attempt to be brief and to the point.

For some infections, such as those caused by some viruses, fever is a normal part of the infection fighting process. But what induces the fever? One possibility is a protein called RIG-1 (retinoic acid inducible gene protein one). This protein is a helicase which recognizes double stranded RNA (dsRNA). dsRNA is often found in viruses but not in uninfected animal cells. This ensures that RIG-1 is only active in infected cells.

RIG-1 causes the release of pro-interleukin, and also activates the transformation of pro-interleukin into interleukin-1. Interleukin-1 was one of the earliest cytokines (proteins which serve important roles in the immune system as well as in cell signaling) discovered. Among other effects, interluekin-1 causes fever.

Prior to the study by Dr. Michael Bscheider and Dr. Olaf Gross, RIG-1 was known to ensure the release of interferon, a type of cytokine responsible for gearing up the cell’s killer cells. These in turn, are responsible for killing infected cells. Now it appears that RIG-1 also affects other cytokines which cause the fever.

As I alluded to in the beginning, there are a host of factors involved in the immune system, many of which play multiple roles. Inducing fever, albeit indirectly, can now be added to RIG-1's repertoire.

Candidates chosen for Mars500

Sorry, you missed your chance.

The European Space Agency and Russia’s Institute of Biomedical Problems (pessimistic name choice?) conducted a search for volunteers to simulate a mission to Mars. The simulation is part of the Mars500 programme conducted by the two organizations.

The search ended last month. Six volunteers were chosen for the simulation from a pool of qualified candidates from member nations. Because the actual trip to Mars is expected to take about 520 days, including 30 days to explore the planet, this group of volunteers will spend that amount of time sealed up together in a facility in Moscow.

Obviously, they won’t be able to test the affects of space flight itself, such as weightlessness, but they will undergo extensive medical and psychological testing.

This 520 day experiment follows a successful 105 day study which was completed in June.