Nature emulating humans

Most of the early manmade polymers consisted of a repeating monomers. In proteins - the biological polymers - this is rare. You could have up to different 20 amino acids in a protein. So when you find a  single monomer based protein, you will sit up and take note. Proteins having long stretches of amino acids like lycine and glutamate are well documented. But when a protein of more than 300 amino acids has only the amino acid called serine - well, it becomes serious.

Serine sequences are coded with a lot of degeneracy: there are six different three letter codes for serine So minor changes in the DNA code at single nucleotide level does not make much difference to the ultimate serine sequence. So it is highly conserved.

And usually, if a protein is highly conserved, it must have some major function. The paper which reports this in a recent issue of the journal Heredity does not explore the functions of the protein. But knowing the central role of the amino acid serine play in the synthesis of nucleotides and also as a precursor to some amino acids, we should expect that a protein made of serine too has very important functions in the cell.

The homopolymer of serine was discovered in a soil amoeba called Dyctyostelium. Dyctyostelium goes through a life cycle consisting of unicellular and multi-cellular  forms and has been used as a model for understanding social organisation. So we should expect that such sequences exist in many other organisms soon.

 Heredity 112, 215-218 (February 2014) | doi:10.1038/hdy.2013.96

Electricity consumers to become electricity producers

Electricity generation from solar and wind energy has been going up at exponential rates in our country in recent years. These sources of electricity are intermittent – only when the sun shines or the wind blows. So storage of energy before distribution as per demand has been posing a problem. 

A study published in Current Science last year pointed out that the problems with inverters are the main cause of inefficient functioning of some of the solar power stations in India. Less costly and more efficient energy storage may soon increase the investment in solar and wind energy projects – if a recent paper on flow batteries in Nature is of any indication. 

Scientists knew that flow batteries where two ionic components are separated by a thin membrane which allows the flow of ions across is a good basis for electrical energy storage devices. But such batteries used metallic compounds and the cost was not worth the efficiency of such batteries. Now a collaborative experiment between American and Dutch scientists have come up with an alternative to metallic electrochemicals for the purpose – quinones.

The technique involves movement of charges across membranes. For the anode, you take quinones which goes through hydroxylation and for the cathode, take bromine which cycles to bromide. Each charge-discharge cycle reduces the efficiency only minimally.

There are many quinones in nature and they can be produced easily. So the cost will be much lesser than the earlier metal based attempts at flow batteries. Moreover, these carbon compounds can hold twice the amount of charge compared to metal based flow batteries. Their efficiency and effectiveness can be modulated by minor changes in different parts of the quinone molecule.

The results come at a time when dye based solar cells are promising to bring down the costs of harvesting solar energy. Combined with low cost, quinone based storage, it may soon be possible that every house becomes a producer of electricity.

Nature, 505, 195–198 (09 January 2014) doi:10.1038/nature12909

Light weight electronics flexible enough to wrap around a human hair

Wrist watch sized communication devices advertised in TV now-a-days will soon be so totally unfashionable. Ultra thin electronics that is extremely flexible and bio-compatible can now be developed very easily.

The key component is parylene, a class of polymers that we have known for the last few decades. It is highly stable, corrosion resistant and can form a thin film. So it has been used as a coating. It is biocompatible and has low friction. So it has been used in catheters and acupuncture needles.

Scientists have now succeeded in making electronics on parylene. Electronics  - sensors, transistors and circuits - is first put on a soluble polymer substrate. Parylene is thermally evaporated on to this substrate. 

The parylene film is released from the carrier substrate by simply dissolving the polymer. Thus you can get a 1-μm thick parylene film containing the electronics!

Electronics of this sort can easily be transferred on any object, surface and even on biological tissues like human skin and plant leaves. The scientists have even tried to put a transparent electronics on top of contact lenses to measure the pressure inside the eye, to detect glaucoma to demonstrate the concept.

A large spectrum of possibilities open up - including ultralight solar cells, implantable devices, rollable and transparent displays, smart-skin and electronic textiles.

To know more about the technique, see the latest issue of Nature Communications.

Nature Communications 5, doi:10.1038/ncomms3982, 07 January 2014

Smaller brothers will be watching you

Imagine, google map updating itself every hour. Imagine if it had a resolution of one square meter on the ground. When an agricultural field is harvested, it would look different – almost real time. You could see the cloud cover changing. You could track the development of a forest fire. Imagine!

Of course right now, if you look at IISER Pune campus, for example, you will see what it was about a year ago. All that might indeed change. Imagine 24 satellites taking continuous photographs and another set of 24 satellites taking videos as they go by. 

If you are anxious about the big brother watching, here comes your world of paranoia. But if you are an enthusiast of military, government and big corporate technologies going commercial, and available to citizens, you may be overjoyed.

In any case, the traffic in outer space is going to be heavy from 2014. The manufacturing techniques used in automobile industry is being applied to satellites: cheaper, lighter, smaller satellites (some weighing as low as 5 kg) will soon be deployed by companies for getting better high resolution images of the earth in a continuous manner.

Nature 505, 143–144 (09 January 2014) doi:10.1038/505143a

When I itches, I scratches

Like the phenomenon of yawning, scientists are fascinated by itching. Itch, like the sensation of burning and pain, are mediated by C fibres of the nervous system - thin, unmyelinated axons found in the peripheral nervous system as well as in the tract that goes up from spinal chord to Thalamus.

It is well known that when a mosquito bites you, histamine is released locally and that it is this histamine that makes you scratch. But in a recent review on the topic in Nature Neuroscience Reviews, you will find a lot more interesting information - including the fact that all itches are not induced by local histamine release.

Nature Reviews Neuroscience 15, 19–31 (2014) doi:10.1038/nrn3641 Published online 20 December 2013

Cameras inspired by Insect Eyes

Popular expositions tend to use camera as a metaphor to understand the functioning of eyes. Now let's turn the table 180 degrees: design a camera based on insect eyes.

Insects, along with the larger group called arthropods (creatures with jointed legs including lobsters and such) have compound eyes. Each eye is made of a large number of simpler units called ommatidia arranged to form an approximately hemispherical surface. This gives a larger field of vision - 160 to 180 degrees - high sensitivity to motion with infinite depth of field. Try catching a housefly or swatting a mosquito on a hot afternoon to appreciate the usefulness of such eyes to insects.

The inventors used recently developed stretchable electronics. They arranged 256 tiny lenses on a 15 mm square elastomer and molded it to a hemisphere to get a compound camera with 180 working lenses! Deformable silicon photodetectors held together by filaments of metal help to integrate the images with appropriate algorithms and computation. Cute, isn't it?

But we still have a long way to go to match the eyes of dragon flies - they have some 28,000 ommatidia in their compound eyes!

Nature 497, 95–99 (2013) doi:10.1038/nature12083

Lamarck resurrected: Inheritance of acquired characteristics

Nearly two centuries ago, Lamarck propounded the theory of inheritance of characteristics acquired by parents in their life time, by progeny. The textbook example of his explanation of evolution claims that giraffe got its long neck by trying to eat leaves from tall trees, generation after generation.

But widespread acceptance of ideas from Darwin, Mendel and the science of molecular biology tolled the death knell of Lamrck's theory. Now it appears that Lamarck will come back, making a grand entry through the science of epigenetics.

Epigenetics is usually about how genes are switched on or off depending on the environment of an organism. Nobody knew that the genes that are switched on will continue to be switched on in the progeny also. But new results show that the epigenetic modifications can and do, pass from one generation to next.

Scientists experimented with mice, giving them mild shocks along with specific smells till they started associating the smell with fear of shock. The children and grandchildren of these mice when exposed to the smell, exhibited fear. Demonstrating that environmental stresses undergone by parents prepare the unborn children to face the same stresses.

Similar studies in  the recent years suggest that biological evolution and cultural evolution are a continuum. It appears that in this century, we may see more biologists entering socio-cultural research.

Nature eurosci. http://dx.doi.org/10.1038/nn.3594(2013)

Sex and violence

A spate of movies with sex and violence has perhaps made us believe that the two go together. Yet new scientific discoveries would have us believe otherwise. 

Indeed, if you put two male fruit flies together, along with a female, you will perhaps find a lot of aggressive behaviour. Yes, even in the lowly drosophila, the fruit fly. And that is quite understandable, given the competition for reproduction.

But if you put males that have had extended contact with females, scientists find reduced aggressive behaviour - even the presence of new females do not elicit violence between the males. 

It appears that previous social contact with females can reduce aggressive behaviour. This reduction in the violent impulse seem to be related to a specific set of neurons in male brains which is activated through pheromones that they come into contact when housed with females.

That is the case of fruit flies. But what about humans? What would you expect to find in post puberty boys-only schools if the result hold true for Homo sapiens?

Nature Neuroscience 17, 89–96 (2014) doi:10.1038/nn.3594

Nature Neuroscience, 17, 81–88 (2014) doi:10.1038/nn.3581