Do They Taste Light?

My previous post was about the fact that C.elegans were sensitive to UV light. What made this more interesting was the protein that was discovered as responsible for this special character.

Conventional studies in these nematodes by Stacey L. Edwards, Kenneth G. Miller, and colleagues allowed them to identify a protein as being behind this interesting property. They called it, lite-1. Curiously, this protein was very similar to those that were known to be involved in tasting. Further investigations established that lite-1 did act as receptor for UV light.

This protein may soon find its way to the tool box of the modern molecular biologists. Perhaps, this protein also shows that there may be other proteins in higher organisms that are waiting to reveal their secrets!

Things are not what they seem to be... especially in the world of biology!

Seeing Light Without Eyes

Many of the ground breaking discoveries in molecular developmental biology were made with the help of simple organisms that can be grown in laboratories with ease. Caenorhabditis elegans is one among them. Measuring about a millimeter in length, these organisms had been a good friend for molecular biologists and neuroscientists for decades. One reason why a common man may find this kind of round worm interesting is that they managed to survive the historic Columbia space Shuttle disaster. (Find more information here.)

These survivors are continuing to surprise their masters and challenging the claim that their physiology is well-studied. Not many would have expected these underground creatures to show any interest in light. Shawn Xu, a neurobiologist from University of Michigan proved just that. Upon observing that these creatures shy away from bright light while he viewed them under the microscope, he set out to explain how these eye-less worms see light.

Further investigations by Xu and his team revealed that four pairs of sensory neurons of C.elegans were responsible for its sensitivity to light. And, these neurons made them reverse their course as soon as the light is switched on.



(Find a more detailed article in ScienceNOW)

It was also found that these worms were more sensitive to the harmful UV-A radiations. This gives a clue to why evolution had gifted these simple organisms with this ability. Without these four neurons and hence the perception of light, the organisms may wander out into the light and get exposed to the harmful radiations. Such behavioral responses to light in such simpler organisms is more crucial to an evolutionary biologist, trying to understand the how higher vertebrates evolved sight.

DNA Crystallization in vivo

Bacteria are some of the marvelous creations of nature. They are known for their adaptability. The humble Escherichia coli that we find in almost all the microbiology and molecular biology labs continues to surprise us with its ingenius ways of handling problems.

Under extreme stress, bacterial cells are known to take many steps to protect themselves. Abraham Minsky of the Weizmann Institute of Science in Rehovot, Israel identified an interesting defense mechanism of E.coli thats slightly different. These unicellular organisms crystallize their own DNA.
This 'novel' defence strategy was found to be the responsibility of a protein called Dps. It resembles ferritin, an iron-storage protein found in humans.

Dps is produced when the cell experiences nutritive or oxidative stress. It binds to DNA (apparently without any specificity) and promotes its crystallisation. Earlier investigations revealed another important function of the Dps protein. It sequesters iron and other metal ions that may help in the generation of free-radicals.


DNA - Dps crystals

Minsky and his collegues genetically engineered a few bacterial cells to over-produce this protein. These cells formed DNA crystals more easily and starvation was sufficient to cause crystallization of DNA. This process was also found to be reversible. "Once nutrients are supplied, [the crystals] disappear within a very short timescale, and the bacteria are viable and growing," says Minsky.

Whats remains to be explained is, how the bacterial DNA integrates itself into a crystal!

Stretching DNA on a chip

DNA carries all information a living organism requires for survival. Reading this information can be made much easier if you can get these 2nm wide polymer strand stretched and untangled. Researchers at Purdue University have done just that.



They have precisely placed strands of DNA on a silicon chip and then stretched out the strands so that their encoded information might be read more clearly. This may prove extremely critical in future electronic devices and computers.

Find more information here.

What made HIV infect Man?

About 4 million years ago, humans had split from apes. At this time, Chimpanzees had to go through some tough times. They were infected with a virus. Scientists discovered this when they found traces of this virus in the DNA of Chimps. This meant that this virus, called PtERV1, infected the Chimp population. Interestingly, the traces of the virus were not found in human genome.

Emerman and his team had an explanation. The humans immune to PtERV1 while Chimps had tough time fighting it. The team of researchers identified TRIM5 as the factor that helped humans protect us from the virus. Removing this protein from the cells made them vulnerable to PtVER1, which were reconstructed from Chimpanzees DNA.

Curiously, these cells were found to be less susceptible to HIV. It seems that in the process of developing resistance to one virus, the immune system of our ancestors had us vulnerable to another deadly virus, the HIV.

Journals Online

Science knows no boundaries!

Here are a few websites that offer free access to some journals on the world wide web!!!

Current Science

BioMedCentral

Directory of Open Access Journals

Free Medical Journals

High Wire Press

PhysNet - Physics related free-access journals

If you know any other such useful websites, please do add those links as comments...

Making alcohol the nano way!

Ethanol (the alcohol) is one of the most talked about alternative for the fossil fuels. For thousands of years, alcohol has been produced from yeast. This way of using biological cells to make alcohol is not generally considered non-viable. Thats because we spend more energy than what we get.

Carbon Nano Tubes (CNTs) are tiny tubes made only of carbon atoms. These are too tiny that the properties of chemicals are often altered when they are in these tubes.
CNTs were found to catalyze the production of ethanol from carbon monoxide and hydrogen. CNTs act either as catalysts or catalyst additives.

In China, its been proven that CNTs loaded with Rhodium nanoparticles as reactors to convert the gas mixture of CO and Hydrogen into ethanol. Dr. Xinhe Bao and his team of researchers in Nano and Interfacial Catalysis Group in Chinese Academy of Sciences observed that the redox properties of metal nanoparticles are modified when they are inside CNTs.




Syngas (a mixture of CO and H2 in the ratio of 1:2) when introduced into the CNT loaded with Rhodium- Manganese catalyst, gets converted to acetaldehyde, acetic acid and ethanol very quickly. The Chinese scientists suggest that this is due to
1) a host guest interaction between CNT and Rhodium - Manganese nano particles.
2) stringent size restriction of metal particles inside CNT.
3) high affinity of H2 to the inner surfaces of CNT.

The DNA message

You probably know that DNA carries the most invaluable information, without which the mere existence of life is impossible. Have you ever wondered whether DNA can be used to store more than just the genetic information? If you had thought of it before, you are not alone(!!!!!!).

A group of Japanese Molecular Biologists in Institute for Advanced Biosciences at Keio University decided to (nearly) immortalize Albert Einstein's magical formula E=mc^2 in the DNA of a bacterium.

DNA is a thread like molecule made of 4 different compounds (represented as A, G, C and T) as building blocks. The sequence of these 4 compounds in the DNA holds the genetic information. The Japanese scientists attempted to translate the formula (along with the year of its discovery, "1905") into binary code. This code was then translated into a language that has A, G, C and T as its 4 alphabets. For example, the binary code '0000' was translated into 'AA' and '0001' was indicated as 'CA'. Once the formula was translated into DNA's language (A,G, C and T), the new sequence obtained was inserted into a bacterial DNA and stored for eternity.

The objective here, was probably to preserve 'the most important formula of 21st century'. Since the genetic information had survived for over 3.5 billion years, DNA was the obvious choice. With the ability to survive in extremely hostile environmental conditions, the harmless soil bacterium Bacillus subtilis was a suitable candidate as the carrier of the "DNA-time capsule".

I hope that these efforts prove successful and Einstein's legacy (E=mc^2) lives on long after the demise of human kind on this planet.

Hmmmm....... I wonder what role the seemingly harmless equation E=mc^2 will play in the extinction of human population!