Genetically-Modified Malaria-Resistant Mosquito Created

[Servant222]

I just posted this in the "Current Affairs" thread at http://www.christianforums.com/t5011499-genetically-modified-malaria-resistant-mosquito-created.html


From the BBC today (Tuesday, March 20, 2007)
http://news.bbc.co.uk/2/hi/science/nature/6468381.stm

A genetically-modified (GM) strain of malaria-resistant mosquito has been created that is better able to survive than disease-carrying insects.

It gives new impetus to one strategy for controlling the disease: introduce the GM insects into wild populations in the hope that they will take over.

The insect carries a gene that prevents infection by the malaria parasite.

Details of the work by a US team appear in Proceedings of the National Academy of Sciences journal.

In the laboratory, equal numbers of genetically modified and ordinary "wild-type" mosquitoes were allowed to feed on malaria-infected mice.

As they reproduced, more of the GM, or transgenic, mosquitoes survived. After nine generations, 70% of the insects belonged to the malaria-resistant strain.

The scientists also inserted the gene for green fluorescent protein (GFP) into the transgenic mosquitoes which made their eyes glow green.

This helped the researchers to easily count the transgenic and non-transgenic insects.

'Fitness advantage'

Dr Mauro Marrelli and his colleagues from Johns Hopkins University in Baltimore, Maryland, wrote in PNAS: "To our knowledge, no-one has previously reported a demonstration that transgenic mosquitoes can exhibit a fitness advantage over non-transgenics."

The modified mosquitoes had a higher survival rate and laid more eggs.

However, when both sets of insects were fed non-infected blood they competed equally well.

For resistant mosquitoes to be useful in the wild, they must survive better than non-resistant mosquitoes even when not exposed to malaria.

Even so, the researchers concluded: "The results have important implications for implementation of malaria control by means of genetic modification of mosquitoes."

GM mosquitoes that interfered with development of the malaria parasite would make it more difficult for the organism to become re-established after it had been eradicated from a target area, they said.

Malaria, spread by the single-celled parasite Plasmodium, is endemic in parts of Asia, Africa, and central and south America.

The organism is passed to humans through the bite of the Anopheles mosquito. Each year it makes 300 million people ill and causes a million deaths worldwide.

Some 90% of cases are in sub-Saharan Africa, where a child dies of malaria every 30 seconds.

Is this an example of evolution in action doing something for mankind's good? Praise God for guiding researchers in this effort!

 

[laptoppop]

No, this is not "evolution in action" -- its just an example of deliberate manipulation of a critter. It would be awesome, however, if it could save lives. I'd be a bit fearful about releasing it in the wild - lots of variables.

 

[Mallon]

No, this is not "evolution in action" -- its just an example of deliberate manipulation of a critter.

Since when did evolution have to be via natural means only? Artificial selection is evolution, too.

I expected your answer to be more along the lines of, "But it's still a mosquito!!!"

 

[mark kennedy]

What makes them think they will not revert back to the wild type? Sure there has to be a selective advantage but even that does not guarantee the changed gene will not revert back to the grandparent form. This happens even when the genes are altered and not mixed with wild type populations. What do you think will happen when they are introduced to the wild.

Evolution is not reversible and this gene has not been fixed in the population.

 

[Servant222]

Wouldn't it be nice if we could somehow put the gene for glow in the dark green eyes in every terrorist. Or make their eye pupils into little red devil shapes.

 

[laptoppop]

Since when did evolution have to be via natural means only? Artificial selection is evolution, too.

I expected your answer to be more along the lines of, "But it's still a mosquito!!!"

No my answer is more like deliberate manipulations are animal husbandry, not evolution. Itty bitty animals in this case, but the changes are man-made/forced not happening naturally.

Breeding strong cattle together to improve the herd - fine to do, but it is hardly evolution.

 

[Mallon]

Breeding strong cattle together to improve the herd - fine to do, but it is hardly evolution.

It's evolution in every sense of the word. Change through time, shift in allelic frequencies, etc.
More importantly, artificial selection is among the best ways to demonstrate/illustrate natural selection in the wild.

 

[laptoppop]

The methodology for creating the variations for natural selection to work on must be included in a TOE. In this case the gene variations were specifically and artificially spliced in - it was not a natural variation. It was engineering, and says nothing about the TOE. Implementing it assumes natural selection - but virtually nobody disputes natural selection.

 

[billwald]

Amazing that God would design a malaria carrying mosquito. <G>

 

[Deamiter]

Hmm... I always thought that the definition of evolution, "change in frequency of alleles over time" was rather succinct and accurate. Now people who don't want to believe it want to redefine it so that it's "change in frequency in alleles over time owing to mutations that are not caused by human meddling with technology"?

And of course, Mark, there's always a chance that the population (not individuals mind you) will lose the artificial mutation due to some so-far unknown selective pressure that selects against malaria resistance. Presumably, though, in a serious attempt to spread the mosquitoes, they'd release enough of them in repeated waves until they were sure they either couldn't compete or the genes had become fixed in the wild populations.

Of course, that any particular mutation might not become fixed in a population is something quite basic to the field of genetics in which evolution is tested daily and still not found lacking.

 

[laptoppop]

I guess I would see an implicit "natural" in front of "change in frequency of alleles over time" -- or else evolution becomes so broad as to encompass a huge amount of typical animal husbandry.

 

[gluadys]

No my answer is more like deliberate manipulations are animal husbandry, not evolution. Itty bitty animals in this case, but the changes are man-made/forced not happening naturally.

Breeding strong cattle together to improve the herd - fine to do, but it is hardly evolution.

Animal (and plant) husbandry works because of the process of evolution. It is built on the same factor that evolution in the wild is: the occurrence of variation which is then selected. The only difference is that human breeders do the selecting instead of leaving that to environmental pressures.

Genetic modification introduces variations which act exactly like natural mutations.

Referring to the process of evolution by a different name does not make it any the less evolution.

 

[laptoppop]

But that is a key difference. Animal husbandry is a directed process. Genetic engineering even more so.

They produce variations with none of the crucial issues such as ratio of beneficial to harmful mutations, etc.

 

[GratiaCorpusChristi]

No, this is not "evolution in action" -- its just an example of deliberate manipulation of a critter.

Agreed.

Evolution is naturally-occuring the process of genetic mutation in certain members of a species that provide them with distinct advantages over others and thus allow them to survive better in their environmental nitch.

Artificial selection is evolution, too.

I would contend that the modern evolutionary synthesis generally refers to the natural mutation of traits, which are then naturally selected through the process of qualitatively increased environmental symbiosis.

This genetically-modifid malaria-resistant mosquito could prove a wonderful thing, but it is not representative of the evolutionary process. It's ability to survive and replace the natural mosquito population will evidence a process of natural selection, but the artificiality of the mutation process nullifies any claim to it being the processes of biological evolution, which is natural in nature.

On the other hand, if the new strain takes root, it will be a further piece of data supporting the process of natural selection among species does occur, given a mutation, whether artificial or natural.

I'd be a bit fearful about releasing it in the wild - lots of variables.

I'd have to agree here, too. I'm always a bit nervous about releasing anything genetically modified- or modified- by humans into the wild.

 

[shernren]

But if you read Darwin's The Origin of the Species (not that I ever finished it) you will see that he uses artificial selection as a piece of evidence for natural selection. The only difference between artificial and natural selection is in the agency of the selection. Because artificial selection is done by humans, its aims and goals will be necessarily anthropocentric; natural selection has no such constraints.

But I can certainly think of some instances where natural and artificial selection would coincide. For example, artificial selection for meat in cows might select for cows with higher muscle mass. The same selection might happen via natural selection if, say, the lions in the area were getting stronger and more ferocious and cows needed to run away faster (or something ). In both cases, weaker cows are drastically forbidden from further participating in the gene pool, and we would expect the same effect, though possibly with different intensities.

This malaria-resistant mosquito thing will be an interesting study of evolution in action. The team has to make sure that their gene for malaria resistance confers selective advantage to mosquitoes. Not only that, if you consider Dawkins' idea of the "extended phenotype", it is clear that those genes would come into conflict with the genes of the malaria parasite itself. If the gene is introduced too slowly into the gene pool of wild mosquitoes, the malaria parasite may well evolve countermeasures that allow it to infect even "resistant" strains; but if the gene is introduced quickly enough, then the anti-malaria genes will "win" and the malaria gene pool will be fragmented or reduced far too quickly for any cogent response to be mounted.

Evolution in action!

 

[Deamiter]

Indeed, I too see little difference between artificial and natural selection. In both cases, individuals with a certain trait (or set of traits) have a better chance of reproducing, and in both cases, those individuals end up dominating the population.

Direction or motivation behind the selection doesn't really matter -- that there are selected traits is the whole point of evolution. God could be doing the selecting by zapping some individuals with traits he doesn't like... the outcome is still a change in the frequency of alleles in an environment.

Successes in genetically engineered crops leads me to believe that these mosquitoes COULD be safe, but I too would be very wary of introducing them into the wild.

In the past, GM crops have caused no more problems than artificially selected crops, but in both cases, they've occasionally taken over other environments. I'm sure it's a major concern of the scientists, but when you start artificially selecting in the Malaria (by introducing the new mosquitoes) it could lead to strains that are resistant to future efforts.

 

[gluadys]

But that is a key difference. Animal husbandry is a directed process. Genetic engineering even more so.

They produce variations with none of the crucial issues such as ratio of beneficial to harmful mutations, etc.

Not when you remember that beneficial mutations are those which are selected for and harmful mutations are those which are selected against. It doesn't really make a difference whether the selecting agent is a natural environment or a human choice.

In general I would be wary of this notion that evolution can only be that which is observed in undirected nature. All scienctific endeavour to understand nature depends to some extent on manipulating nature and seeing how it responds. Take away the tool of human manipulation of natural environments, and you take away an important tool for any understanding of nature, not just evolution.

What we do have to confirm is that the process we see when we manipulate nature also occurs without human manipulation. That doesn't mean that the process itself is different just because some factors were controlled by humans for human purposes.