Climate causes correlations

Climate science has been getting some unwanted attention these days. Like the hoo-haa about HIV, in this case too, people are learning to be less sensationalist. When examining primary principles, one comes across quite a few studies that encourage us to pay heed to the need to be cautious lest one confuses correlations with causes. A recent paper by Sze Ling Ho and Thomas Laepple in Nature Geoscience is yet another in the series.

Surface temperatures of the seas and vast oceans of the planet play a big role in the climate change calculations. To model climate change, scientists use a proxy temperature index, TEX H 86, derived from the relationship between archaeal lipids and temperature. But use of this proxy in the climate model leads to unexplainable warm polar sea surface temperatures in Eocene - about 50 million years ago. This has been a bee in the bonnet for many climate scientists.

Now, this paper comes as a consolation and a cause for further worry. TEX may not be a good proxy for surface temperatures. But it is still very useful, since it is actually measuring subsurface temperatures.

If that does not worry climate researchers who insist that they see climate warming in the future, I see it only as a reflection of Tony Blair's "conviction" about weapons of mass destruction in Iraq.

Nature Geoscience 9, 606–610 (2016)doi:10.1038/ngeo2763

Climate causes correlations

Climate science has been getting some unwanted attention these days. Like the hoo-haa about HIV, in this case too, people are learning to be less sensationalist. When examining primary principles, one comes across quite a few studies that encourage us to pay heed to the need to be cautious lest one confuses correlations with causes. A recent paper by Sze Ling Ho and Thomas Laepple in Nature Geoscience is yet another in the series.

Surface temperatures of the seas and vast oceans of the planet play a big role in the climate change calculations. To model climate change, scientists use an proxy temperature index, TEX H 86 derived from the relationship between archaeal lipids and temperature. But use of this proxy in the climate model leads to unexplainable warm polar sea surface temperatures in Eocene - about 50 million year ago. This has been a bee in the bonnet of many climate scientists.

Now, the paper comes as a consolation and a cause for further worry. TEX may not be a good proxy for surface temperatures. But it is still very useful, since it is actually measuring subsurface temperatures.

If that does not cause worry to climate researchers who insist that they see climate warming in the future, I see it only as a a reflection of Tony Blair's "conviction" about weapons of mass destruction in Iraq.

Nature Geoscience 9, 606–610 (2016)doi:10.1038/ngeo2763

Sleep-Wake Cycles: Magnanimity of Magnesium

All of us know how the sleep-wake cycles work in us: behind our eyes, just below where the optic nerve from the eyes cross, there is the pituitary gland that has melatonin which increases and decreases in response to light and makes us sleepy or awake. Right?

Wrong. Circadian rhythms are found even in plants that do not have eyes or pituitary. Circa means about, dian refers to day. The clock that is inbuilt in living creatures has fascinated biologists and in the last few years we have seen discoveries of a large number of clock genes. So it is not the nervous system that is responsible for the daily cycles, but the clock genes, right?

Wrong. Says a paper in yesterday's Nature. Behind the evolution of clock genes, behind the evolution of pituitary, is the magic of magnesium.

The daily pendulum of human and algal cells, separated by more than a billion years of evolution, swing in response to intracellular magnesium. The element is needed in modest and meagre amounts, and is critical for life: magnesium is a cofactor in all ATP dependent processes. In other words, metabolic energy yo-yos with magnesium. And that sets the pattern for the evolution of clock genes, the evolution of the nervous system with a pituitary that releases melatonin...

The magnanimity of the modest magnesium!

Nature 532, 375–379 (21 April 2016)

Risk Takers Turn Risk Aversive:

We do not normally take risks. Yet, at times, we do. Scientists in Stanford University tell us why, in the recent issue of Nature. They have succeeded in turning risk taking rats into risk aversive ones by timely stimulation of dopamine type 2 receptors in some specific cells of the Nucleus accumbens.

The nucleus accumbens is generally considered the reward centre in the brain and is implicated in addiction. But given the results that are pouring in about the nucleus, perhaps it is more involved in decision making than in addiction.

Nature 531,642–646 (31 March 2016)

New method for dieting: Brain control

The sense of hunger and feeling of satiation after eating are mediated by cells in the lower part of the hypothalamus in the brain. Scientists have found ways to remotely activate and inhibit this region specifically without any surgical intervention. Genetically encoded nanoparticles that respond to radio signals of magnetic stimulation were used to activate glucose-sensing neurons in the ventromedial hypothalamus of live rats. This was found to increase plasma glucose and glucagon, lower insulin levels and stimulate feeding. Inhibition reduces blood glucose, raises insulin levels and suppresses feeding.

So, if you have been planning to diet and never got around to doing it yet, wait for some more time. The technique demonstrated in the lab might soon be around since there is enough demand.

Nature 531, 647–650 (31 March 2016)

Mobile Phones to Measure Tidal Forces

Many cell phones today have microelectromechanical systems that can detect acceleration. By tweaking the system a little, these devices can detect acceleration due to gravity, claims a paper in a recent issue of Nature.

The new device is sensitive enough to detect tidal forces on earth. From being a mere accelerometer, it becomes a gravimeter that can measure tidal forces.

Most present gravimeters are heavy. But this new device is so light that you can use it on a drone and let it survey the land. It will give you clues about underground reservoirs of oil, magma etc.

By putting the device into handphones, and crowdsourcing the data while people travel around, we will be able to map what lies underground.

Nature 531, 614–61(31 March 2016)

Unpunished corruption leads to more corruption

In our society, many cases of corruption go unpunished. Prevalence of rule violations (corruption, tax evasion etc.) tends to reduce intrinsic honesty in young people, says a recent paper in Nature.

More than 2500 young people from 23 countries took part in the experiment. Researchers conclude that

"weak institutions and cultural legacies that generate rule violations not only have direct adverse economic consequences, but might also impair individual intrinsic honesty that is crucial for the smooth functioning of society".

The message is clear: if you want to reduce corruption and tax evasion, punish the guilty and let the public know that economic offences will not be tolerated. This would have implications on lying and dishonest behaviour even in other realms of day-to-day life.

Regeneration of Lens after Cataract Operation

In the latest issue of Nature, there is a report of lens regeneration after cataract operation. Till now this was thought to be impossible. But Chinese and US scientists joined hands to prove that it is indeed possible. The trick is simple enough: when you remove the lens, be careful not to remove stem cells. But in practice, it requires a totally different operating procedure. Scientists find that if they retain cells that express Pax6 and Bmi1 genes, lens does regenerate and visual function is restored.

They first did experiments on rabbits and macaques. And they demonstrated that the same procedure works in human infants with cataract.

Cataract is one of the leading causes of blindness. The finding that it is feasible to allow the lens to regenerate using endogenous cells may revolutionise cataract operations.

Dilemma of being a neuron

If you were a neuron, you would need fast excitatory transmission and fast synaptic inhibition. The first - fast excitatory transmission - is mediated by AMPA and the second - inhibition - is mediated by GABA.

Since the inhibition by GABA is mostly in the synapses and the excitation is in the body of the neuron, you will have to package them and transport them to two different destinations. Or you could just send them generally to the plasma membrane and let them settle down where they are needed. 

What will you do?

If neurons were people, the answer would have been easy. But neurons don't talk. So you have to quiz them with scientific procedures and protocols. A recent paper in PNAS, Differential vesicular sorting of AMPA and GABAA receptors, does just that. Using total internal reflection fluorescence microscopy  in combination with immunocytochemistry, electrophysiology, and electron microscopy methods they confirm what method neurons use to distribute the receptors in different parts of the cell membrane.

Here is a short video from the report:

It appears that neurons are rather sensible. They package the goods into vesicles in golgi bodies and transport them separately to different destinations as per the need.

Does Winning an Election Increase Corruption?

Winning a competition contributes to subsequent unethical behavior, claims a paper in PNAS, based on a series of studies. Winners behave more dishonestly than competition losers.

The paper by Amos Schurra and Ilana Ritov from Israel provides evidence to show that winning a competition increases the likelihood of winners stealing money from their counterparts in a subsequent unrelated task. But the effect holds only when winning means performing better than others and not when success is determined by chance or in reference to a personal goal. The results also show that a possible mechanism underlying the effect is an enhanced sense of entitlement among competition winners.

Now I understand why, with each election, corruption grows.

PNAS 113  (7): 1754–1759 (2016)      doi/10.1073/pnas.1515102113

Terrestrial Biodiversity hotspots and marine populations

I read a General Article in Current Science twice. I was to write an invitation to read it. The content was significant. But the style was horrible.
Anyway, what fascinated me about the article was a map of biodiversity hotspots in the world. I kept looking at it again, to distract myself from the painfully didactic text and kept wondering - what is common between these sites, so far apart geographically?
I could not take the picture from the article. So here is one from commons.wikimedia.org/

One hypothesis presented itself - these are new kinds of land forming...
After I finished writing the page in Current Science, I sat back to relax. And then I come across this paper in PNAS - "Geomorphic controls on elevational gradients of species richness" by Enrico Bertuzzo et al. in  PNAS  vol. 113  no. 7  1737–1742  February 16, 2016.
Not bad. My instincts were right when I wrote the invitation to read the paper on Biodiversity in Current Science.
Another paper that I had to introduce in the next issue of Current Science dealt with fish populations in the sea. So I could not help wondering whether the claims of this PNAS paper  - based on simulations - is true for the sea also.
So I went back to look at the PNAS paper again. At the end of the paper there is acknowledgement of funds received from... - the Swiss Federal Institute of Aquatic Science and Technology!
Not bad. The way content from diverse papers connect up. 

A sigh of relief: peptide that controls sighs found

It is not only relief, but often sadness or exhaustion may also cause sighing - a long breath. And, of course, there are also sighs without any of these - a spontaneous sigh that helps to reinflate the alveoli of your lungs. So what is the most proximal cause of sighing?

The center in the brain that controls breathing (retrotrapezoid nucleus) sends signals to the respiratory rhythm generator in the brain (preBötzinger Complex). These signals consist of two peptides: neuromedin B and gastrin-releasing peptide. A shot of these peptides elicits sighing. Blocking either of these peptides reduces sighing and blocking both peptides eliminates it altogether.

Whether it is relief from tension, emotions, tiredness or any other distal causes, this is the peptide that ultimately sets off a sigh.

A report in the recent issue of  Nature - 8th February 2016 - looks into the peptidergic control circuit for sighing.

Are you a morning person or a night owl?

Sleep researchers have been identifying genes that determine whether you get up early and go to bed early or lead a hectic life late at night, finding it easier to sleep into the morning hours. The first clock gene found was per in drosophila a few decades ago. The gene influences the circadian rhythm. And then a few more followed, one by one. Now in a fell swoop, using genome wide association studies, of self reported morning persons, scientists have identified 15 loci that contribute to the habit of rising early in the morning.

Interestingly, getting up early and going to bed early does not necessarily make you healthy, wealthy and wise. Excess body weight, depression etc have also been implicated for the tendency to rise early. But these factors do not seem to figure in the genetic analysis. Yet.

Nature Communications has open access report. Take a look.

http://www.nature.com/ncomms/2016/160202/ncomms10448/full/ncomms10448.html

New clues in the genetics of Schizophrenia

There is a paper in the latest issue of Nature that spells the development of a new perspective on schizophrenia. The paper by Aswin Sekar and others identifies the genetic risks for schizophrenia.

It was well known that the Major Histocompatibility Complex (MHC), the genetic system that forms the basis for the distinguishing of self and the other by the immune system, has a strong association with schizophrenia. But the genes and molecular mechanisms for this had not been identified. The recent paper in Nature does exactly that.

There are many structurally diverse alleles of the complement component 4 (C4) genes of the Major Histocompatibility Complex in Chromosome 6. These alleles produce widely varying levels of C4A and C4B proteins in the brain. In schizophrenia, there is more of the C4A protein.

The C4 proteins are localized mainly in neuronal synapses, dendrites, axons, and cell bodies. They are responsible for synapse elimination during postnatal development. The over expression of C4A proteins thus explains the reduced numbers of synapses in the brains of individuals with schizophrenia.

The findings are significant since now one can focus on genetically modifying the expression of the C4A allele. I predict that there will be more papers in this direction this year itself.

Aswin Sekar et. al. Schizophrenia risk from complex variation of complement component 4, 

Nature (2016) doi:10.1038/nature16549