The Kaye Effect

Watch and be amazed at non-Newtonian fluids!

Evolution - could it cure malaria?

Wired and Seed have reports of an interesting story about GM malaria-resistant mosquitoes that could eventually be released to combat malaria. The strategy the mosquitoes are being developed to implement rests squarely on the concepts that evolutionary biologists use to understand how populations change over time. So it begs the question, could evolution cure malaria?

Malaria is a disease caused by a parasite, specifically protists in the genus Plasmodium, carried by Anopheles mosquitoes. Plasmodium has a complicated life cycle in which different stages of the organism take over and eventually burst forth from human liver and red blood cells, causing a range of deadly symptoms in humans infected with the disease. The malaria parasite are endemic in Africa and Asia, causing up to 2.7 million deaths a year and making it the leading cause of death worldwide.¹

Understandably, some way to prevent infection is a public health priority in hard hit areas such as Africa. Treatments exist for malarial infections, but they are often too expensive or hard to obtain for many people living in areas endemic to the disease. The parasite is also developing resistant to many of the once-effective treatments at a startling rate, making treatment increasingly difficult. For many years, researchers have attempted to create a vaccine against the Plasmodium parasites. This is a difficult task since these Sporozoans are such complex organisms; unlike the simple DNA strands and protein coats of viruses, Plasmodium are full-fledged multicellular eukaryotes. To make matters worse, there are four separate species that are responsible for the majority of human malaria!

But Jason Rasgon and his team at Johns Hopkins University have taken a different approach. Instead of preventing the infection of people, they focus on the parasite's other host: the Anopheles mosquito. By genetically engineering resistance to the malaria parasite and releasing them into wild, malaria-infected populations of mosquitoes, they hope to change the frequency of human malaria infections through evolution.

How does this work, and what does it have to do with evolution? Evolution by natural selection works in the following way. 1) New mutations arise in the genetic code of individuals, changing their phenotype, in breeding populations of organisms. 2) These phenotypic differences, physical manifestations of the genetic code, infer some competitive advantage to the mutants, causing them to breed and produce more offspring than their "wild-type," normal counterparts. 3) Over many generations, these competitive differences cause the frequency of the mutant phenotype increases relative to the wild-type until the wild-type either disappears or comes to some low "fixed" frequency in the population. Nature has "selected" the mutant phenotype because it is able to produce more offspring than the wild-type.

In this situation, the mutant-type is the GM malaria-resistant mosquito. Carrying the malaria bug represents a significant cost to normal mosquitoes, so the mutant GM mosquito would have a competitive advantage over the wild-type mosquito if released into wild populations. Knowing how natural selection can affect the frequencies of traits, we can predict that the GM resistance trait would take a firm hold in the wild population. Less malaria-carrying mosquitoes mean less malaria-infected people.

This frequency change is precisely what Rasgon's laboratory experiments demonstrated. The frequency of malaria-resistant mosquitoes in the trial increase from 50% to 70% in nine generations.

It sounds like an excellent idea, but it's far from being ready for field tests. Rasgon's group used a species of Plasmodium that infects mice instead of humans. Their laboratory insects were also subjected to much higher rates of malarial infection than normal populations. However, they are excited by the results of their experiments and will begin work on developing a mosquito that is resistant to human varieties of the parasite.

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1. Check out the CDC's malaria page for more information and statistics: http://www.cdc.gov/malaria/.

Could it really just be confusion?

Time magazine has a short piece trying to make sense of recent comments by Rev. Albert Mohler, president of the Southern Baptist Theological Seminary. Mohler, an influential member of the fundamentalist movement, admitted that homosexuality might be a product of biology and not a lifestyle choice. He went on to say that science would probably find a way to "fix" gay babies.

I have two things to say about this article. First, I would like to point out this gem of reason. Mohler writes:

We sin against homosexuals by insisting that sexual temptation and attraction are predominately chosen,

and clarifies the statement in a Time interview:

But that is not true. The Scripture doesn't say we are responsible only for the temptations we choose. The basic sinfulness of homosexuality, that wouldn't change.

So basically, gays can't help it, but they're still evil. Awesome, I'm glad that makes so much sense.

Second, I would like to focus on a very interesting statement made by another prominent evangelical, President Richard J. Mouw of nondenominational Fuller Theological Seminary in Pasadena, CA:

Evangelicals, and I am one, haven't always exhibited very clear thinking about science and spirituality.

Wow, whatever would give him an idea like that? Fundamentalists only drive cars, ride in airplanes, and study physics but refuse to believe in evolution. They even call it the "theory of evolution," although they don't call gravity the "theory of gravity." They'll allow themselves to be treated with modern medicine but will not allow science to take medicine further if it means hurting a ball of human cells. They'll accept that the Earth goes around the sun, but... well OK, some of them still don't accept that the Earth goes around the sun.

Fundamentalists have been anything consistent when dealing with science. They like to pick and choose the science they believe as much as they like to pick and choose scriptures to follow or ignore. But one has to wonder if most of the inconsistencies are due mostly to ignorance. Take this paragraph from the article:

Mohler responded that he opposes genetic manipulation of all kinds. His point, he said, was that if a hormone therapy were developed for fetuses that would help them be born straight rather than gay, he would support its use, just as he would support medical treatment to give sight to the blind fetus.

Let's ignore for the moment how obnoxious it is to think that there is something about gay people that need to be "fixed" and instead look at the statement itself. What, exactly, is the difference between treating a disease or condition with hormones as opposed to genetically fixing it? You would be paying drug companies for your entire life in the former, where genetic correction would make your body produce the same correcting chemical for you.

Talk about inconsistent! It seems like there is a serious disconnect between this guy and science reality (as opposed to some kind of designer-baby science fiction). Somehow, hormone treatment (i.e. taking a pill for it) is acceptable whereas gene therapy is out of the question. Maybe we're just having a similar disconnect between evolution and evangelicals... could it really be that simple?

...probably not.

Save the blood-sucking parasites!

I'm sure you've heard of campaigns with similar names before, "Save the Whales!" or "Save the Owls!"  But there are hundreds of parasites on the brink of extinction, too.  And what's more, they aren't even listed on the IUCN Threatened Species list! 

So why would anyone care about parasites? 

This is an important ethical question.  When the last of the California condors were rounded up and taken into breeding programs to boost populations, their species of louse, able to live only on California condors, were literally dusted out of existence by humans.  What makes the California condor more deserving of salvation than its louse?  Because the condor has a backbone and the louse doesn't?  Because the condor has two eyes and a mouth (like us) and the parasite doesn't?  Because we can sympathize with its situation but not with that of the louse?

The question of conserving biodiversity is a tricky one.  If our aim is to conserve nature and shear numbers of species, then all species should be equally protected.  That means adding 48 species of blood-sucking ticks to the IUCN red list.  Parasites are an essentail part of nature and in that respect deserving of our conservation efforts.  Even though they aren't quite as cuddly as the panda bear or majestic as a soaring eagle.

Then again, what would it be like if the WWF's mascot was a flea?

Here's an article expounding on this question and an additional importance of parasites: host-specific parasites coevolve with their hosts, giving scientists valuable information on the evolutionary history of both the parasites and its more charismatic host. 

John Bush in Monterey

John Bush from MIT is coming to Hopkins Marine Station on Friday to give a lecture entitled "Surface Tension in Biology." I will be driving down to hear it, and I'm planning to write up a post during the weekend.

Professor Bush, applied mathematician, has worked on surface tension questions regarding how water striders and small insects move on water. His team built Robostrider, a mechanical water strider as well as a plethora of other cool stuff, including awesome pictures like the one to the left. This is a gorgeous visualization of the vortices shed by a moving water strider.

Check back!

I don't even know what to do with that, part II

We recently handed back exams in the class that I TA and were excepting regrade requests from the students. Here is a sample of one of the better ones:

I think my diagram/labels should be fairly clear for anyone that has even a basic knowledge of cell divison.

Now, someone explain to me why anyone would ever write that on a request for more points. The most it can accomplish is to piss off whoever graded it (i.e., me). If it were in the context of a rational argument or even had anything to do with why this student missed the points they were after, then maybe I could understand it. But neither of those were the case. It was just a student who either misunderstood what the question was after, or misunderstood the biological process itself, and blamed whoever graded the test. Without even bothering to understand why it was marked wrong in the first place.

I don't even know what to do with logic like that.

I don't even know what to do with that

You try so hard to be a fair as a teacher.

And then you run across people with bad attitudes. People who are never satisfied, no matter how much time or energy you put in. People who think you aren't being fair, no matter how clear grading is. People who think everything that goes wrong is someone else's fault.

I spend hours and hours teaching every week, too much time some would say. I spend extra time trying to make things in an introductory biology class interesting and fun so people won't leave the class thinking bio is a dull and boring discipline or at least leave without hating science.

I spend hours grading assignments and exams. I spend time making sure I am being fair and consistent in my evaluations. I spend time making the scales and grading transparent, so students can understand the grade they get. I spend even more time making comments on their work so they can improve their grades and performance.

So naturally, when a student accuses me of not grading them fairly, I get irritated. Especially when they cannot explain why they were graded unfairly, other than "I should pass because I was here."

I'm sorry, but since when has the ability to fog a mirror guaranteed passing? Certainly not in my class. And at what school? Certainly not mine.

I may be wrong about this, but there seems to be this idea among students that if you don't do well, it's someone else's fault. If you get a low grade on a test, it's the grader's fault. If you don't get a good lab grad, it's because the TA wasn't clear.

I don't even know what to do with logic like that.

They're Made Out Of Meat

Short film based on the short Sci-Fi story by Terry Bisson.