Register for an account

X

Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.

X

Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

Planet Earth

There Was an Old Parasite That Swallowed a Plant ...

By Josie GlausiuszMay 1, 2003 5:00 AM

Newsletter

Sign up for our email newsletter for the latest science news

Trypanosoma brucei, a protozoan that causes African sleeping sickness, is a bizarre product of symbiosis: An ancient ancestor of the parasitic organism swallowed a microscopic alga and evolved into a deadly plant-animal hybrid. Molecular parasitologist Fred Opperdoes of the Catholic University of Louvain in Belgium reached this conclusion after scrutinizing T. brucei's genome.

The microbe swims freely through the blood and feeds off its host, behaving like the single-celled animal it is, but it produces enzymes and lipids thought to be exclusive to plants. Opperdoes and his colleagues found that the parasite's DNA harbors at least 16 plant genes, including one that codes for an enzyme that plants use to produce sugar via photosynthesis. In T. brucei, the enzyme works instead to break down sugar sucked from the victim's blood. "A billion years ago, a primitive, free-living, amoebalike protozoan ate an alga, and the alga stayed inside," Opperdoes says. "This was a tremendous advantage, because an organism that previously had to swim around to find its food was now capable of photosynthesis. Later it turned into a parasite and the alga was lost, but some of its genes moved into the nucleus." This discovery could lead to novel ways to fight T. brucei. Herbicides that attack the plant-based part of the genome could finally spell the hardy parasite's downfall.

2 Free Articles Left

Want it all? Get unlimited access when you subscribe.

Subscribe

Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%

Subscribe

Already a subscriber? Register or Log In