A Step Towards Less Harmful Insecticides

A new generation of mosquito repellents would soon be in the market, if a recent paper in Nature is any indication. Anandshankar Ray and others report that they have identified the specific receptor in the antenna of the fruit fly that responds to a common insect repellent. Then, using computational methods, they screened more than 400,000 molecules that could potentially activate the receptor. And identified more than 100 that could.

Then they selected the ones that have minimum unwanted effects on human beings and tested for their ability to repel mosquitoes. Four of them were found most successful while not affecting humans at all. In fact, they had a mild aroma of grapes. Moreover, they did not dissolve plastics and are therefore more amenable to packaging compared to the existing mosquito repellents  and less costly to produce. Scientists speculate that the repellents may have applications in controlling vector borne diseases and agricultural pests.

Nature(2013) doi:10.1038/nature12594, Published online 02 October 2013

Why is Swine Flu virus called H1N1?

The swine flu virus swept through Pune this July and here is a feature that looks at the phenomenon retrospectively and reflects on the prospects of such epidemics in future.

It is called H1N1 - H stands for haemagglutinin and N stands for neuraminidase - two proteins found on the virus. Haem-agglutinin helps the virus to attach itself and gain entry into to our cells. The virus replicates itself in large numbers there. Neuraminidase helps these newly formed viruses to come out of our cells.

There are many variations of these proteins in influenza viruses. In fact scientists have identified 16 types of hemagglutinins and 9 types of neuraminidases. 144 different combinations are possible...

Naming the virus by number of the subtype of the two proteins became a convention that allows unique name to all these types of influenza viruses. Bird flu that swept the world a few years earlier is another, called H5N1.

Influenza viruses infect many birds and mammals. Quite often, humans in contact with such birds or animals also get infected. But it is rare that the virus then moves from human to human. In such occasional cases, we see a sudden epidemic of Influenza in human societies. The swine flu which swept through Pune in July was just such a case. 

Quick identification of the type of influenza virus is useful to create a vaccine in response to an epidemic. But the vaccine would not be useful later because these viruses undergo rapid changes through both genetic drift as well as genetic shifts -

abrupt changes in their genome.

In most cases, the flu is self limiting Our immune system comes to the rescue and we would be alright in a few days. Symptomatic treatment of the fever and malaise is also often used, to reduce the suffering. In some rare cases, anti retroviral drugs and neuraminidase inhibitors are also used. 

Origin of Jaws

Can you imagine if we did not have jaws? We would never be able to talk - yak yak yak..

And now scientists have discovered the beginnings of the evolution of our jaws. In China, they have discovered the fossils of a fish, the first vertebrate with jaws, that lived more than 400 million years ago.

Nature (2013) doi:10.1038/nature12690. Published online 25 September 2013

RNA Switches for Bacterial Virulence

A bacteria known as meningococcus, causes septicaemia and meningitis in children. This bacteria is quite prevalent in the nose and pharynx of humans. Yet we are normally protected by our immune system. But then, how does it suddenly infect humans? What does it do to fool our immune system?

Scientists have started unfolding the mystery with the finding that there are three RNAs in meningococcus that respond to the increasing temperature.

The hairpin bends in these three RNAs melt and separate out and that starts the transcription of three proteins. These proteins help the meningococcus to make a new kind of cell wall and to escape detection by our immune system.

Interestingly, for meningococcus, these RNA switches are a response to the threat of increasing temperature. The increase due to fever in the human body.

Such transitions from innocuous to virulent pathogens are known to happen in many other micro-organisms. The results published in Nature online in September may be a clue for many other researchers to start looking at RNA switches in other pathogens too.

Nature (2013) doi:10.1038/nature12563, Published online 25 September 2013

Carbon Computers

All life forms on the earth are Carbon based. And speculations have been abundant about the possibility of silicon based life.

Meanwhile, all computers are based on silicon. And attempts have been made to create carbon based computers. And now scientists have made a breakthrough.

Computers based on carbon nanotubes are indeed possible, says researchers from Stanford university. Read the paper in the September issue of Nature.

Nature 501, 526–530 (26 September 2013) doi:10.1038/nature12502

Jab the sperm met the egg

Ok, all of us know that we were formed by the combination of an egg and a sperm. But did you know that when the egg and sperm joined to become a zygote, initially all the work was done by the genes from the egg?

It is only after the first few divisions that both the gene sets from father and mother kick into synergised action.

And then on, it is a zygotic genome.

Till then, the cells are pleuripotent meaning each cell can become any organ. But from this time the cells start differentiating. to a large extent become unique and start responding to the neighboring cells and the surrounding environment...

There is a very interesting paper on this phenomenon in the recent Science journal, if you are interested... 

Combined with the fact that your energy production mechanism, the mitochondria, come from the mother, the continous early divisions of the fertilised egg reminds one of the efforts of the mother in creating you.

Science 341, 1005 (2013); DOI: 10.1126/science.1242527

Whistling Radio

You guys should be glad that you are listening to FM radio. Tune in to short wave, if you don't believe.

There is a huge amount of whistles and screeches and unbearable noise.

And no wonder. Our sun is very active now, sending out particles, mostly charged...

They come and hit against the magnetic field causing magnetic storms on  the earth's field and change directions themselves. Some of them come in through the poles and get trapped in the magnetic field. And soon the ionosphere swells up in response. Moving a few miles closer to the earth's surface.

Since short wave radio depends on reflection of the radio waves from the ionosphere, and the ionosphere is changing, reception becomes problematic.

Besides, the trapped electrons are sometimes accelerated by the changing magnetic field lines of earth, leading to emission of radio waves. And that is what we hear as screeching and whistling noises in short wave bandwidths.

By the way, the sun is at its peak activity and is expected to change its north south magnetic orientation. Flipping of the field takes place every 22 years or so. Wait for more in the coming posts.

And for an interesting report on the acceleration of particles in the van Allen belts, high up in the earth's atmosphere, take a look at the recent paper in Science Magazine.

Science 341, 991- 994 (2013); DOI: 10.1126/science.1237743

Conductors: Soft, Stretchable and Transparent

Electronic devises are usually hard materials. Suppose you want a devise which is stretchable, you could use metallic springs.

If you want them small as well, you could use nanomaterials - like silver or gold nanowires. Or carbon tubes, graphene, ..

These materials conduct electricity, electronically. Meaning - electrons move in the material to conduct electricity. But if you want it soft and stretchable and transparent?

Say, for instance, to implant them in human body?

You might think that the choices would narrow down. But instead, it just expands...!

Many hydrogels can conduct electricity. Are stretchable and transparent and even biocompatible.

Unlike the hard materials hydrogels are ionic conductors. Can withstand very high voltages and very high frequencies. Which expand the applicability to many technological problems.

Researchers can now have a field day generating applications with these materials.

There is a trail blazing paper in the recent issue of science.

Take a look.

Science 341, 984-987 (2013);