Already, people are making money from the "swine flu" epidemic - both the nefarious and the opportunity-grabbers.
This is to be expected in a capitalistic world. You try to make money at the margins of opportunity. In this case, those margins are a) the fears of a population mass, and b) the attention of a population mass, respectively.
If I was superstitious, I'd be concerned that the first Australian case of this flu was a man who comes from just down the road (Coogee), and who contracted it from a holiday in Puerto Escondido, Mexico - where I too have holidayed. But I'm not superstitious.
It reminds me of the near-hysteria of the SARS epidemic six years ago. Epicentre Honk Kong, which contains a good mass of superstitious people. I told my colleague from Hong Kong that a good way to make money would be to market a potion claiming to prevent SARS, guaranteeing to pay a penalty compensation if it didn't work. You'd make your money from the large numbers sold, as against the small number of purchasers who subsequently contracted the illness.
Sure enough, a few weeks later a Hong Kong business was marketing a soft drink claiming to prevent SARS - or your money back (not even a penal return promised).
Efforts of the World Health Organisation are credited with breaking the back of SARS - which is why WHO has reacted so strongly to this Mexican outbreak. Still, my feeling has been that this is over-reaction, particularly since the number of fatalities has been small - and revised down - and has so far been confined to Mexicans (one of which was resident in the US).
SARS was far more virilent - the death rate was higher. I can't help wondering whether the main outcome of this current epidemic will be reduced economic activity - and a small prolonging of the current global recession.
Showing posts with label virus. Show all posts
Showing posts with label virus. Show all posts
Sunday, May 03, 2009
Friday, September 12, 2008
The role of the virus in evolution, part 2
To summarise:
Viruses have a wide variety of forms and actions. For just about every type of organism from animals to plants to bacteria, there are viruses that infiltrate them. Some viruses attack a broad range of cells; some are specific to specific kinds of cells: tissue tropism defines the set of cells/tissues that a given virus attacks.
Some viruses attack germline cells (those involved in reproduction); some of those (endogenous retroviruses) can insert their own DNA into the germline cell's DNA, which means some viral DNA can end up getting passed on to subsequent generations by the host organism.
Thus we have Human Endogenous Retroviruses (HERVs). The end results could be quite varied. It's feasible that this is the source of much junk DNA (that is, DNA which doesn't fulfill any [known] function in the developmental process). Yet that inserted DNA could be harmful: HERVs are suspected of involvement in a range of auto-immune diseases, including multiple sclerosis.
On the other hand, the recent New Scientist article on viruses (here, called in the print version Welcome to the virosphere) suggests ERVs have also played a crucial positive role in the human immune system's ability to respond to viruses never encountered before.
And HERVs have been linked to gene regulatory networks, which determine which genes are activated and deactivated. Thus they appear to be a key enabler of evolutionary change: "the main difference between closely related species is not in genes themselves, but how they are expressed" (ie whether and when they are activated).
Patrick Forterre, of Paris-Sud University, has been studying DNA mechanisms since the 1970s. His analysis of DNA across the three domains (bacteria, archaea, and eukaryotes [organisms with cellular nuclei, ie most of us]), found disparate DNA-related connections across each pair of domains that weren't present in the other. His ultimate conclusion (see this PNAS article for some of the detail) is that at an early point in the evolution of life there was "a period of wild biochemical experimentation"; innovative mechanisms were shared between different life forms through gene transfer by viruses. Forterre posits numerous alternative life systems, of which all that is left is the three domains, plus remnants of the rest surviving in the virosphere. Given that viruses are more abundant than any other organisms, and gene flow is greatest via viruses, "it should not be a surprise that major innovations could have occurred first in the viral world, before being transferred to cells".
In effect, viruses have been "sharing the successful [biochemical] experiments" - those mechanisms that survived in the DNA being the successful ones. Forterre goes further and credits viruses for many leaps in complexity of life, including development of DNA from RNA, and the key innovation of cell nuclei.
Ultimately, the NS article concludes that as species, we are "leaky vessels" of DNA, and that the biosphere can be seen as one "interconnected network of continuously circulating genes - a pangenome".
Viruses have a wide variety of forms and actions. For just about every type of organism from animals to plants to bacteria, there are viruses that infiltrate them. Some viruses attack a broad range of cells; some are specific to specific kinds of cells: tissue tropism defines the set of cells/tissues that a given virus attacks.
Some viruses attack germline cells (those involved in reproduction); some of those (endogenous retroviruses) can insert their own DNA into the germline cell's DNA, which means some viral DNA can end up getting passed on to subsequent generations by the host organism.
Thus we have Human Endogenous Retroviruses (HERVs). The end results could be quite varied. It's feasible that this is the source of much junk DNA (that is, DNA which doesn't fulfill any [known] function in the developmental process). Yet that inserted DNA could be harmful: HERVs are suspected of involvement in a range of auto-immune diseases, including multiple sclerosis.
On the other hand, the recent New Scientist article on viruses (here, called in the print version Welcome to the virosphere) suggests ERVs have also played a crucial positive role in the human immune system's ability to respond to viruses never encountered before.
And HERVs have been linked to gene regulatory networks, which determine which genes are activated and deactivated. Thus they appear to be a key enabler of evolutionary change: "the main difference between closely related species is not in genes themselves, but how they are expressed" (ie whether and when they are activated).
Patrick Forterre, of Paris-Sud University, has been studying DNA mechanisms since the 1970s. His analysis of DNA across the three domains (bacteria, archaea, and eukaryotes [organisms with cellular nuclei, ie most of us]), found disparate DNA-related connections across each pair of domains that weren't present in the other. His ultimate conclusion (see this PNAS article for some of the detail) is that at an early point in the evolution of life there was "a period of wild biochemical experimentation"; innovative mechanisms were shared between different life forms through gene transfer by viruses. Forterre posits numerous alternative life systems, of which all that is left is the three domains, plus remnants of the rest surviving in the virosphere. Given that viruses are more abundant than any other organisms, and gene flow is greatest via viruses, "it should not be a surprise that major innovations could have occurred first in the viral world, before being transferred to cells".
In effect, viruses have been "sharing the successful [biochemical] experiments" - those mechanisms that survived in the DNA being the successful ones. Forterre goes further and credits viruses for many leaps in complexity of life, including development of DNA from RNA, and the key innovation of cell nuclei.
Ultimately, the NS article concludes that as species, we are "leaky vessels" of DNA, and that the biosphere can be seen as one "interconnected network of continuously circulating genes - a pangenome".
Monday, September 08, 2008
The evolutionary significance of viruses, pt 1
The DNA that makes up the human genome is the blueprint for the biochemical processes that constitute the embryonic development of humans. That's all that is really needed: a recipe for the step-by-step development of a baby. The DNA is a long chain of instructions for the creation of proteins that, in the right order, conduct the chemical processes.
And that human genome contains a lot of DNA that came from viruses.
There's debate about whether viruses are 'living' - but at one level, that's just semantics. They are organisms that cannot survive outside a host, and consist of little beyond a strand of DNA (or RNA) and the mechanism to breach a host cell and use the host to help replicate the genetic material.
Retroviruses are so called because their genome is RNA, and they use a reverse transcription process to make DNA equivalents of that RNA. That DNA can end up being integrated into the host cell's DNA (with the help of an integrase enzyme).
That in itself would have no evolutionary significance, except that it's possible for that DNA integation to happen in any germline cells - that is, one of a successive set of cells that would ultimately create the sperm and egg cells. If so integrated, the inserted DNA would then become inherited.
This is the endogenous retrovirus, ERV, and according to a recent New Scientist article, 8% of the human genome clearly comes from that source, and over 50% probably does.
And that human genome contains a lot of DNA that came from viruses.
There's debate about whether viruses are 'living' - but at one level, that's just semantics. They are organisms that cannot survive outside a host, and consist of little beyond a strand of DNA (or RNA) and the mechanism to breach a host cell and use the host to help replicate the genetic material.
Retroviruses are so called because their genome is RNA, and they use a reverse transcription process to make DNA equivalents of that RNA. That DNA can end up being integrated into the host cell's DNA (with the help of an integrase enzyme).
That in itself would have no evolutionary significance, except that it's possible for that DNA integation to happen in any germline cells - that is, one of a successive set of cells that would ultimately create the sperm and egg cells. If so integrated, the inserted DNA would then become inherited.
This is the endogenous retrovirus, ERV, and according to a recent New Scientist article, 8% of the human genome clearly comes from that source, and over 50% probably does.
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