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.

Smoking Out Y


When people smoke, not only do they inhale burnt pieces of paper which damage their lungs, or have tar accumulate inside of them, which is likely to cause lung cancer, or inject nicotine into their bloodstream, which increases heart rate and blood pressure; it also causes the Y chromosome to eventually disappear. Of course, this only affects males, since the presence of a Y chromosome determines you’re male in gender, but for women smoking is still unhealthy and should be stopped.

Chemicals in tobacco affect this chromosome during cell division or mitosis when the chromosomes are being separated to either sides of the cell. Damage to the chromosome can build up until it eventually disappears. The study, carried out in Sweden, showed that people (men, specifically) who smoked had 33% more chances of loosing their Y chromosome compared to men who didn’t smoke.

However, it has been widely thought for many years that the Y chromosome is so small (in fact, it’s the smallest out of our 46 chromosomes), that its loss wouldn’t have too dire consequences. Past experiments on cells show that they can survive just as well without said chromosome. But new studies show that the lack of this chromosome, although not directly fatal, can shorten life duration and causes an increase in the likelihood of developing cancer. Lung cancer or any other cancer having to do with the respiratory system aside, male smokers are twice as likely to develop cancer as female smokers.

A possible explanation for this is that the Y chromosome contains tumour suppressing genes, so if it disappears, tumours are not going to be controlled and inhibited and therefore will be able to reproduce uncontrollably, causing cancer.

The newest research shows that this effect changes intensity depending on the dose of tobacco smoked. Obviously, the more tobacco you smoke, the more likely you are to suffer from its negative effects. But there’s a silver lining: this process is reversible. If you were to stop smoking, your cells would stop taking damage and after some time they’d be repaired, so you would have the same percentage of healthy cells with a Y chromosome as a non-smoker.

y chromosome

The Y chromosome is more important than you think in the fight against cancer

 

Genesexual


gene

Although genes could now have a very important effect on men’s sexuality, the environmental impact is still significant

In the largest study on the matter up to date, scientists from Illinois have investigated the DNA of hundreds homosexual men and have found revolutionising results that show that being gay could have a strong genetic influence.

Although the genome is a vast structure, home to thousands of genes, there were two very specific areas contained in it that were analysed in detail. Both these areas have been known by the scientific community for quite some years. For example, one of them, located in the X chromosome, and called Xq28, was first suspected to be related to homosexuality in a smaller study in 1993; whereas the other one, 8q12 in chromosome 8, was discovered in 2005. The aim of this experiment was to confirm these areas had some effect on sexuality in men and investigate how they caused this effect.

Overall, 818 men, all gay, volunteered for this project. This is almost 20 times more people than in the study in 1993. But to make it reliable as well as statistically accurate, many of the test subjects were brothers; in some cases, even non-identical twins! Having two closely related individuals with similar genetic makeup can make differences in their genome stand out and their distinct effect on the phenotype much easier to find. Using DNA collected over many years from blood samples, the scientific team looked closely at these men’s gene sequence. They were looking for small differences in the coding between brothers, specifically for single nucleotide polymorphisms, which are changes of only one base or nucleotide in a gene. After all the DNA samples were analysed, 5 single changes in the nucleotides were observed, and most occurred in these two regions of the genome.

What makes this study’s results worth considering is the fact that the only feature all these men shared was their sexuality: they were all gay. They varied in every other physical feature; so any change in those areas of their genome that was common to all men had to be related to their sexual orientation.

But both Xq28 and 8q12 are filled with genes, so although we know almost certainly that there are genes in there related to homosexuality, there is still not a distinct list of genes that could cause someone to be gay. Finding them hidden in these large areas full of coding is the team’s next task.

This discovery has, as could be expected, grave implications. It could help resolve all discrimination against gay people, and show that their sexual orientation is not a choice, but actually who they are. But unfortunately, it could lead some people to consider homosexuality as a biological mistake or a negative mutation, and even resort to genetic engineering to identify and remove ‘gay genes’ from embryos. This is wrong on many levels, but the most related to this article is that a person’s sexuality is not only defined by their genes, but is also affected by the environment they live in, so changing their genes is unnecessary and would not prevent homosexual people from being born.

Robot Yeast


A milestone in biology was reached this month when scientists in USA were able to create an entirely synthetic chromosome from a Saccharomyces cerevisiae, commonly known as yeast, in the lab.

chromosome

A chromosome has been created for the first time in the lab, step by step

To start this process they identified the full genetic sequence of yeast’s chromosome III, chosen because it’s one of the smallest chromosomes and can therefore be replicated more easily.
But it was still too big, so they took out a few less than 45,000 nucleotides, all of those thought to be ‘junk’ DNA, that is, DNA that doesn’t seem to have any function. This left 270,000, all of which had to be joined together to make up the chromosome, starting from scratch.
This is an enormous amount of work, so they ended up working with a team of 60 undergraduates, each team building a part of the chromosome until they were all joined together to form the final masterpiece.
Once the chromosome was ready, they inserted it into the yeast cell, and fortunately it seemed to work just as fine as the natural one would. They are now working on repeating this task on the whole of the yeast’s genome, instead of only one chromosome.

There have been some experiments in the past which managed to recreate the genome of organisms, especially bacteria, but no one up until now had managed to change it so much and still have it work. It is an outstanding feat in science that could teach biologists a lot more on how genes work and interact with each other.

However, this achievement is not only good in the way of creating artificial life, but it could also show some improvements in the chemical industry world.
When they decided which nucleotides to take out, they also haad to chose some changes to be made to the genome, so as to learn something from the genes changed. One of these tweaks was to change the stop codon, TAG, to TAA. This meant that TAG now doesn’t code for anything, but scientists could change this so it codes for a new amino acid, not found in the cell before. This could give rise to new substances and biopolymers, whose properties could prove to be very useful. If this worked, we could eventually have cells become factories, all with changed genetic sequences, so they produced new chemicals for many possible functions.