Evil Twin’s Downfall


So what if we have an evil twin, like in the movies? If he/she commits a murder, and DNA evidence is found in the crime scene, both you and your evil twin will be suspects, since you share the same genetic material. Although this is a rare and unlikely scenario, it is definitely a possibility, and has actually happened several times throughout the years.

Usually, this will end in no one being prosecuted, since it would be impossible to determine which twin did it, and sending both to jail would be terribly unfair to the innocent sibling. A new option for the police in these cases is to analyse the DNA of both twins in incredible detail, searching for any slight variations that may have randomly occurred due to mutations and changed the genetic code, but this option takes a lot of time (over a month) and also happens to be very costly.

twins

Now we can find out which twin actually did it

However, scientists have now come up with a sort of an upgrade to this method. Instead of looking for mutations, which occur randomly, they would look for differences in the DNA strands that have been caused by their way of life. These modifications are called epigenetic changes, and instead of causing a gene to change its sequence of bases, it just modifies how it is expressed into a protein. It can do this by adding a methyl group (-CH3) or by altering the histones in our DNA: the proteins that help condense our genetic information into a more compact shape so it can all fit into the nucleus of a cell.

These changes can be inherited, which would be unhelpful since both twins can have them, or caused by environmental factors, which would also be unhelpful if the twins have lived close together in the same conditions. Fortunately, very small differences can cause these changes, specifically in the early stages of the embryo’s development, so although still rare, these changes do exist in twins.

In the specific case of epigenetic changes by methylation, this would mean that the DNA strand is now larger, and has more molecules in it. This would increase the forces of attraction and increase its melting point. Since both twins will have different changes, and therefore different amounts of methyl groups, their DNA would not melt at the same temperature. So comparing their DNA’s melting temperature with that of the DNA found in the crime scene can tell the police which of the two twins did it, and solve the mystery in a much faster and cheaper process, as you only have to heat the suspects’ sample.

XNA Alternative


DNA and RNA have always been considered miracle molecules thanks to their ability to self-replicate and create life. Everyone thought that they were the only molecules that could carry information on how to code for an organism and pass this down for generations. But what if I told you there were other molecules capable of doing the same thing?

This group of molecules is called XNAs (Xeno Nucleic Acids) and they all are a polynucleotide strands but each with a different repeating monomer. They still have a base and a phosphate group attached; what changes is the sugar in them. Whilst DNA uses deoxyribose and RNA uses ribose, XNA can use a wide variety of sugars, like theorose, or other unrelated chemicals, like peptides.

DNA XNA

This is a normal DNA strand – XNA is the same but with a different sugar in the nucleotide

Not only do they copy the structure of a nucleotide and therefore form a nucleic acid, but they can also store information in the form of bases. However, to make XNA carry bases in a desired order, scientists have to use an enzyme that copies the coding from a DNA strand and passes it onto an XNA strand. Once there, another enzyme can read the bases in the XNA and copy them onto DNA, and if needed, back to XNA. This means that an old XNA can technically pass information to a new XNA molecule, even if it uses an intermediate molecule; this process is basically evolution.

But this discovery is from back 2012. The current news involves XNA being able to act as enzymes, apart from encoding possible genetic information. They still can’t form copies of themselves in the traditional sense, but they can manipulate RNA and even add XNA fragments to an XNA strand. The fact these molecules are enzymes and can modify themselves to some extent makes it more feasible that at some point they will be able to self-replicate, and behave just like DNA did, to evolve into a new type of life.

It is also further proof showing that XNA is a viable alternative to both DNA and RNA, and that the reality that all living organisms we know use these nucleic acids could be arbitrary. In fact, it could be perfectly possible than in other galaxies, organisms use XNAs instead of DNA. Of course, this is only a theory, and we have to take into account the conditions of an environment without any life. RNA and DNA could have developed because they were more likely to appear in the first place, for a reason unbeknownst to us yet.

Cancer’s Gene Struggles


It’s been a very productive week for cancer research. There’s been a new protein discovered which almost tricked everyone into thinking it was helpful against cancer, and scientists found that just by cancelling some genes tumour growth can occur. Seeing as interesting these discoveries are, let’s delve into them.

First and foremost, let’s talk about the p35 gene. This section of the DNA produces a protein, called p35 protein (who knows why), that can detect abnormal cells, and then start to kill them to prevent them from reproducing, therefore preventing a tumour from forming. This has been known for more than 30 years, and by now we thought we knew all there was to know about it. But the discovery of a variant of this gene hit the news this week. Said gene is called the p35-psi gene, which produces another protein, chemically similar to the p35 protein, which also caused an inflammatory reaction in mutated cells, just like p35 does. But after further study, scientists discovered it does the complete opposite of its cousin: it encourages the growth of cancerous cells. The mechanism works by p35-psi teaming up with another protein, cyclophilin D, which together change the mitochondria organelle so the whole cell itself transforms into a new type, similar-looking to a muscle cell, which usually precedes a cancer.

This opens up a door of possibilities for cancer treatments. New drugs could target cyclophilin D, to stop the transforming process from occurring. Or they could suppress the p35-psi gene to stop it from producing the harmful protein in the first place

 

Cancer Cells

Cancer cells divide uncontrollably, even if they have a mutation which would normally be eliminated

Now moving on to the second piece of news.

We all know how mutations can lead to cancers, but the novelty here was that inactivating genes also caused the disease. This can be done through a process called epigenetic methylation, because a methyl group is added to a gene and so prevents it from being transcribed.

Epigenetic methylation occurs naturally in our cells, and actually helps them repair their DNA. But when this process occurs over and over by continuously exposing the same genes to methyl groups, they might just end up permanently attached, effectively cancelling the gene.

The problem, however, is that it is not known for certain whether epigenetic methylation is a cause of cancer or if cancer causes this methylation. In the study carried out, scientists added a new gene into mice cells, a gene that specifically attracted methyl groups and caused methylation in nearby genes. And speaking of tumour suppressing genes, the team in this investigation concentrated on the effects of methylating gene p16, which also prevents the growth of tumours. Over the course of the experiment, those mice with the injected gene had an increased chance of developing cancer, especially in areas like the spleen or the liver.

Although this information does seem to indicate methylation causes cancer, some researchers argue that maybe when they added the new methylating-prone gene, they messed with the already existing genome so it mutated and turned the cell cancerous.

However, since methylation definitely has an effect on cancer, the group of researchers at Baylor College of Medicine in Texas, where the experiment was carried out, will now focus on investigating a way of reversing this process in cancer cells.

It is interesting to note that methylation occurrence can be linked to our diet, since methyl groups come from the food we consume. Some products like green tea and broccoli help decrease methylation rate, so it might be time you had a sip of some delicious tea just in case.

2013 Review Part 2


In the previous article we saw how scientists from all around the world had managed to print a gun, create a fake burger and allow a human and a rat to communicate only using their minds! We also saw how two excelling scientists were honoured with the most prestigious scientific award, the Nobel Prize, for their theory of how particles gain their mass. Last but not least, we reviewed the meteor that hit Russia and fascinated observers and astronomers alike.

But 2013 was a very busy year, and there are still things that have to be remembered. For example:

6. Life Can Be So Hard

lakevostok

Lake Vostok in Antarctica

Humanity has not yet found a planet with living organisms in it, because conditions can be very harsh and inhospitable, unlike in our planet. Or maybe not.  I’m talking about Lake Vostok, in Antartica, where this body of water rests under 500 metres of ice, under extreme temperatures and pressure, and where no sunlight can reach. Immediately, you’d think there can be no life here, but a team of Russian scientists proved last year that there may be, when they drilled through all the ice and extracted a sample of water that contained pieces of DNA.

If life is definitely found, it will most probably be single-celled organisms, not macro-organisms such as fish or sharks, although if there’s anything we’ve learned from this adventure is that life can be found in the most unprecedented places, not matter what form it takes.

7. The Memory of the Smell of Fear

rAt

Memories travel generations in rats

A study carried out last year showed that memories can be transmitted from one generation to the next, and not by talking about it. The case was that a group of rats were subjected to the smell of cherry blossom, and after this, gave them an electric shock, so every time they smelled this, they would become wary and tense. Then, these rats were reproduced, and, surprisingly, the children also became alert when detecting the smell.

Although the mechanism is not yet understood, it may have something to do with changes in the DNA (like switching on and off certain genes) due to chemicals being released in your body.

This phenomenon can happen with other events, not just smell, but others are more difficult to track, since there are a lot of genes involved. Smell, specifically cherry blossom, is easier because there are specific receptors that react to this smell, which scientists already know about, so changes in these can be seen easily enough. Also, its not only the fact that the offspring must remember the smell, but also the feeling that comes with it, fear.

8. The Oldest DNA

In a cave 30 metres below ground, a paradise for archaeologists lies. There, the oldest genome ever discovered has been processed, yielding incredible results.

denisovan

Denisovian Hominid

This fantastic place is the Atapuerca cave, found in Spain (my home country), and has always been considered a gold mine for anthropologists. It continues to meet its expectatives, as in a shaft, they found the remains of 28 hominids, of which a thigh bone was extracted. Although extracting a good sample of DNA from such an old sample, especially in a warm climate, is very improbable, scientists tried anyway, and thank God they did. The genome found is 400,000 years old, twice the age of our current species. The surprising thing about his genome is not only its antiquity, but also that it shows the bones found in the shaft known as ‘the pit of bones’ is not Neanderthal, but of a different species of humans called Denisovan, of which very little is known. But with this discovery, maybe we will find out all we need to know about them, and complete the puzzle of our many ancestors.

9. The Most Crowded Trench 

mariana

Mariana’s Trench, the deepest point on Earth

Director James Cameron, known for movies such as Titanic, Avatar or The Terminator, will be remembered by the scientific community for more than his movies.

Last March, he organised the Challenger Deep expedition, which travelled 11000 metres underwater to the lowest point of Earth, the Mariana’s Trench. He stayed there for about an hour, collecting samples and recording everything he saw.

Although the area was not teeming with macro-organisms, unfortunately for Cameron, samples from the submarine show there were unusually high levels of bacteria in the water. For every cubic centimetre, there were 10 million bacteria, a surprise for scientists because the amount of organisms down there was higher than in shallower areas, where conditions are less hostile. A possible explanation is that trenches are extremely good at collecting ‘food’ (organic matter from creatures above), so bacteria would have enough material to survive, even though the pressure and temperatures are not too comfortable.

 10. Blob of Pitch Falls

Pitch, a substance that makes up petroleum, is also one of the most viscous substance known to man, and its qualities can be quite interesting.

Decades back, someone in Trinity College Dublin set up an experiment that consisted in adding a measure of heated pitch to a glass funnel, and then let gravity do its job. The original version of this experiment, however, was done in University of Queensland, Australia, by Thomas Parnell, whose objective was to show and measure how viscous this liquid really was, though he died before it could actually happen.

pitch

The Pitch Experiment

But it was in Dublin where the magic really happened. After years of the pitch standing abandoned in an old shelf, scientist Shane Bergin found it, and after figuring out what it was, set up a web cam and connected it to the Internet so everyone was able to observe the liquid, in case a drop fell. And that is precisely what happened, the 11th of July, after years and years of patience. Although the real purpose has been completed, the web cam is still connected, and it is expected that in the next decade, another drop falls, so be attentive.

Switching ON the junk


Scientists from all around the world may soon be able to read the genetics version of the book of life, detailing everything from the human genetics and DNA structure.

These exciting news start in 2003, when the American research facility, the National Human Genome Research Institute, created the Encyclopedia of DNA Elements (ENCODE for short) a project to find out all they could about the human DNA sequence.

In 2007, the results of the ENCODE were published, listing pages and pages of all the codes of DNA and finding out that about 98.8% of our DNA doesn’t do anything, adopting the name of junk DNA.

Since then, the research has been increased, and very fascinating details have been discovered. Just recently, they have found out that 19% of our DNA, codes for an RNA, that may work as a switch to turn on and off different genes on different parts of the body. The mechanism is still not clear, as not all of it is understood. For example, biologists have yet to comprehend why most of these switches are spread out over the genome, and not just near the gene they control.

Though this discovery is a milestone in genetics, it’s not the end of the story. It has still much to teach us, and researches have still yet to be made to uncover all the secrets lying in the complex structure of our DNA.

Sources:

http://www.newscientist.com/blogs/shortsharpscience/2012/09/global-project-reveals-what-ou.html

http://www.guardian.co.uk/science/2012/sep/05/genes-genome-junk-dna-encode