Can Smokers be Wiped out by Natural Selection?

One interesting thought!! Can Natural Selection wipe out the smokers from the Earth after years of evolution? The study results point to a similar direction.

First of all, the smoking habit has to be a genetic characteristic (inherited property in other words) to be qualified to take part in evolution. Scientists, in fact, claim to have discovered the gene linked to smoking habit. The study by Dr Hidetoshi Nakamura of Keio University in Japan looked at a particular gene known to have an effect on how people process nicotine. In the human body, nicotine is mainly metabolized by the gene CYP2A6.If people are not very good at processing nicotine, then they are less likely to be interested in smoking and less likely to continue if they do start. In another study by Dr Robert Walton, of Oxford's clinical pharmacology department, variations of a gene known as the dopamine D2 receptor gene, or DRD2, reveals whether individuals are genetically programmed to be addicted to nicotine. One in three people is born with the gene.

Now let's see how the smoking habit can make us disadvantageous to reproduce. British researchers published a study claiming that a life of cigarette smoking will be, on average, 10 years shorter than a life without it. They also claimed that consistent cigarette smoking doubles mortality rates in both middle age and old age. More interestingly, Men who smoke cigarettes may experience a significant decline in their capacity to father a child, a research by a reproductive medicine specialist from the University at Buffalo indicates. Like other cells in the body, human sperm carry a receptor for nicotine, which means they recognize and respond to nicotine. The results could mean that heavy smoking overloads the nicotine receptor in human sperm and in the testes, leading to a decline in fertilizing potential. Not only that, the same study claims, smoking men also should be aware that smoking can damage their sperm DNA, passing on faulty DNA to their baby.

To sum up, smokers are likely to have less life-span with less probability to father (or mother) a child. If we bring together all theree studies, the platform for differential reproduction rate to wipe out a genetic variety seems to be in effect. Isn't those enough to stop spreading the genes for smoking? To answer in brief : No, as memes are there to manipulate.

This is where importance of memes comes to picture. Let's take an example of Indian women. They generally don't smoke because in Indian societies, smoking by women is almost prohibited. So, they carry the 'smoking gene' to pass it to the next generation as successfully as other women would have done. The smoking gene doesn't stop spreading because of the meme present in Indian societies to prevent women from smoking. The strong Indian social structure defies the Natural Selection on smokers. In a nature versus nurture debate, in this case, nurture seems to have won - and the habit of smoking will last longer in protective societies. To wipe the habit out, we require the introduction of a new stronger meme to stop smoking itself. The meme is: "Smoking is injurious to health" - and we need a strong awareness campaign.

Reference : Meme and it's activities (my old post)

Darwin, DNA, Evolution, Meme, Genetics, Science

To Change the Species - Just Change the Genome!!

The news appeared in most of the leading newspapers that scientists have successfully transplanted the entire genome of one species of bacteria to another. This is carried out by the institute lead by J. Craig Ventor, a prominent participant in the human genome sequencing.

The researchers worked with Mycoplasma mycoides (a microbe that infects goats) because it has one of the smallest genetic blueprints of any known self-replicating organism and lacks cell walls, making it easier to insert new DNA. They isolated its entire genetic code - one chromosome that forms a circle-stripping it of all its proteins, and then added genes to make a host organism blue (to make it easy to pick out in a Petri dish) as well as resistant to the antibiotic tetracycline. The scientists added close relative Mycoplasma capricolum (another goat pathogen) to a solution containing M. mycoides' genetic material and gently mixed it for a minute. After three hours of incubation, the resulting microbes were exposed to the antibiotic tetracycline.

The Evolution and Natural Selection are played once more in the labs as the variants having favorable mutations (artificially imposed) survived and the rest perished. After three days, large colonies of blue, antibiotic-resistant microbes had formed. Roughly one in 150,000 of the M. capricolum microbes had absorbed the new DNA and transferred it to daughter cells. The daughter cells displayed no trace of their original DNA while taking on the entire form and function of the original bacterium.

The ultimate goal is to make cells that might take carbon dioxide out of the atmosphere and produce methane, used as a feedstock for other fuels. Such an achievement might reduce dependency on fossil fuels and strike a blow at global warming.

Scientists remain unable to create synthetic life in the lab. "If we're trying to understand the origins of life and cellular life, it would be ideal to have all the chemical components in a soup to spontaneously go together and form a cell", Venter says, "We're a long way from that."

References :
1. Sciam
2. NYT

DNA, Evolution, Genetics, Origin of Life, Science

Genetics to Biotechnology

It was always a challenging task for human beings to produce the ‘human-hormones’ outside a human body. The reward was well known. A disease caused by the lack of this particular hormone can be cured easily by injecting that artificially produced hormone.

Let’s take the case of Insulin. A patient of Diabetes requires regular injection of Insulin since their body fails to produce it naturally. Until 70’s, the major source of Insulin was domestic mammals like cow and pig. Due to close evolutionary relationship with human beings, this Insulin was almost similar to human insulin in structure. Hence, these sources used to work for most of the cases. However, there were side effects of this method – like skin rashes.

The advent of a couple of technological breakthrough changed the entire scenario. First, the DNA was discovered. Then it was established that the amino acid sequence in DNA strands are actually replicated in ribosome to produce different proteins. In other words, the DNA code on the chromosome works as a template to the protein produced in the cell. The other milestone was the discovery of Recombinant DNA – a form of DNA that is achieved by combination, insertion and deletion of more than one DNA strands.

Bacteria have a second set of DNA molecules other than those in their Chromosome. This is called a plasmid. The successful strategy by a company named Genentech to produce Insulin uses these plasmids efficiently. Genentech researchers produced artificial genes for each of the two protein chains that comprise the insulin molecule. The plasmid is then inserted into the bacteria named E. Coli. The bacteria multiply and at the same time produced either of the two protein-chains, in presence of lactose. At the end, the bacteria are killed and the Insulin chains are separated. The protein-chains are then merged to produce Insulin.

The fact is that the person who discovered Recombinant DNA – Herbert Boyer, started Genentech. He was funded by a venture capitalist, Bob Swanson. They formed the World’s first Biotechnology firm, with a capital of close to $1000. However, when they were ready to launch their product, Eli Lilly was the market leader in Insulin business with 85% market share. Genentech avoided the collision and signed contract with Lilly to market their product. In September 1980, Genentech went public. The share price shoot up from $35 to $89 within hours of trading and both of them became instant millionaires.

The same concept of Recombinant DNA is used even today in Biotechnology, to produce artificial proteins, and getting used in every sphere of Life. A chapter of the book DNA : The Secret of Life by James Watson, is dedicated to various biotechnological efforts. The most interesting one is described like this :

So-called dragline silk, which forms the radiating spokes of a spider web, is an extraordinarily tough fiber. By weight, it is five times as strong as steel. … the silk-protein producing genes have been isolated and can be inserted into other organisms, which can thus serve as spider-silk factories. This very line of research is funded by Pentagon … soldiers may one day be clad in protective suits of spider-silk body armor.

Something that started with innovations ended up making money once more. With the advent of Biotechnology, the prime focus of research in Genetics took a new turn to include commerce in the agenda. For human society, the research that started with Watson-Crick Double Helix model slowly begins to produce fruits in direct application.

Reference:

1. DNA The Secret of Life by James Watson : Chapter Five titled as – DNA, Dollars and Drugs: Biotechnology
2. Biotechnology describes the Insulin production process.
3. Wikipedia
4. Protein Synthesis described.
5. History of Insulin.

The Origin of Life : RNA Hypothesis

Of late I have been reading books by great scientists. The best one as I found out, is one from James Watson, named as DNA : The secret of Life. I have gone through first three chapters of the book only. It has given me a lot of knowledge on how the life has been evolved on the earth.

The basic mystery that I had prior to reading the book was on the relation between protein and life. The explanation tha I got is really interesting. It's the DNA that replicates a part of it (transcribes) to messenger RNA. The messenger RNA then comes to Ribosome and gets translated to amino acids with the help of transfer RNAs present there. Amino acids are catalyzed by RNAs to build polypeptide bonds among them to generate Protein. But, DNA, RNA and the Proteins are built on nucleotides.

Here the RNA World hypothesis comes into picture. It's now obvious that RNA has a property to store, transmit and duplicate the genetic information as DNA. It can also produce proteins - the building block of life. According to this hypothesis, RNA was independent initially and later evolved a barrier outside to form later form of life - like bacteria and Amoeba. Carl Zimmer, who's working on this for long, believes that RNA Viruses are the last common ancestors of life. They evolved into DNA based viruses and since then, the superior system of DNA based life exists.

The most interesting part to me was the role of Natural Selection in the process of forming RNAs. Initially nucleotides (purely chemical substance) were free floating. They were often formed bonds to bind together. but certain sequence of bonds had properties to bind and go to more stable state. As each chain grew longer it attracted more matching nucleotides faster. RNA is one of these giant nucleotide chains. In an RNA world, different forms of RNA compete with each other for free nucleotides and are subject to natural selection. The most efficient molecules of RNA, the ones able to efficiently catalyze their own reproduction, survived and evolved, forming modern RNA. The competition grew and resulted in co-operation between separate RNA chains to produce more and more different proteins. DNA came later and so lipids, carbohydrates and other materials since a collaboration of such materials were more 'sustainable' and 'replicable'.

The main problem of this thesis was the instability of RNA while being exposed to UV Rays. Recent experiments also suggest that the original estimates of the size of an RNA molecule capable of self-replication were most probably vast underestimated, the size can be smaller than one have thought of. More-modern forms of the RNA World theory propose that a simpler molecule was capable of self-replication (that other "World" then evolved over time to produce the RNA World). There are many more hypothesis surrounding this RNA and life but the lack of undisturbed sedimentary rock from that early in Earth's history leaves few opportunities to test any of these hypothesis robustly.

The idea of RNA world was first proposed in Carl Woese's The Genetic Code. The term was coined in 1986, by Walter Gilbert.

The origin of life on earth is a mystery that Humankind ought to solve. The proper understanding might give us several advantages over the natural world. We may create our own microbes to fight against the diseases caused by virus and bacteria. We will have much better understanding of each of the building blocks of our own body.

News Reference from BBC :
Creation of Viral life by researchers.

DNA, RNA, Evolution, Origin of Life