MEDIA
CLUB SOUTH AFRICA. COM 11/5/12 BY Wilma den Hatigh. Professor Louis du Preez from North-West University has discovered five new
parasite species in the rain forests of French Guiana in South America.
A renowned
South African researcher has discovered five new parasite species – considered
by many scientists to be nigh impossible to find – in the rain forests of
French Guiana in South America.
Professor
Louis du Preez from North-West
University (NWU), who is an expert on flatworm parasites that live in
amphibians and fresh water turtles, didn’t know that his research mission to
the remote South American forests would yield such a remarkable find.
Du
Preez says the parasite species were found in a caecilian, a legless
earthworm-like amphibian, in turtles and in a frog.
"We
knew beforehand that chances of finding this caecilian were slim, and
those of finding the parasite in one even slimmer,” he says.
“Our
best scenario was to get one, and we got five.”
Answering
questions about amphibians
He
says although the discovery is not of veterinary or economic importance, it
will help researchers to answer important evolutionary questions about
amphibians and their geographical location.
“Now
that we have the DNA of the parasite we can find out how its hosts evolved,” he
says. “Amphibians were around long before dinosaurs, yet they survived when dinosaurs
became extinct.”
Du
Preez, who is also an authority on frogs, says it is important to research
these amphibians as their survival is critical for a healthy ecosystem.
Frogs
are the most threatened vertebrate group in the world because of habitat
destruction and the threat of disease and fungi.
“Frogs
are important because they eat vast quantities of potentially harmful insects
and serve as staple food for some birds and reptiles. Wherever frog numbers are
in decline, there is a disruption in the ecosystem.”
An
unusual research trip
Du
Preez’s search for the parasites started when the National Museum of Scotland contacted
him about a parasite they discovered in a caecilian which had been preserved in
a bottle of formalin for 120 years.
Scientists
were examining the specimen as part of a study on the reproductive organs of
caecilians.
But
the scientists couldn’t study the DNA as it had been destroyed by the formalin.
The
only solution was to find a living sample – and the aim of the research mission
was to find the parasites in a caecilian so that the DNA could be extracted.
“We
needed to search for a live parasite,” Du Preez says. “It was a huge gamble because we were told that we didn’t stand a
chance, but we decided to go and look anyway, and on day two we found it.”
Into
the jungle in a banana boat
A
team consisting of Du Preez, Oliver Verneau from the French
National Centre for Scientific Research (CNRS) and an NWU postdoctoral
student, Mathieu Badets, travelled to the virtually inaccessible area of the
French Guiana forests in search of the elusive parasite.
Du
Preez describes the research mission and discovery as one of his career
highlights.
They
first stayed at the CNRS base in Cayenne before embarking on a gruelling
120-kilometre trip upstream on the Approuague River in a dugout canoe, also
known as a banana boat.
“It
took seven hours to travel up the river to reach our destination,” he tells.
The
team was based at a remote French scientific research base in the Nouraques
Reserve next to the river.
“There
are no roads to access it, and the only way is by helicopter, which is very
costly, or a banana boat, which is much more cost effective,” Du Preez
explains.
They
had to take all their equipment and microscopes with them, but the base is well
equipped with basic infrastructure and food kept in freezers.
The
base lies only four degrees north of the equator and du Preez says the team had
to work in hot and rainy tropical conditions, with a constant threat of
venomous snakes and jaguars.
“We
never slept on the floor. I spent two weeks sleeping in a hammock while at the
research base,” he says.
Finding
the parasites
Du
Preez explains that they were only allowed to catch two kinds of aquatic
turtles as part of their research.
The
turtles were kept in containers filled with water, after which the water was
examined for the parasites. Three aquatic caecilians were also caught in the
reserve and in one of the caecilians they found the rare polystome, or
flatworm.
"Now,
at last, we could extract the DNA from the parasites to see where they fit into
the evolutionary development process,” Du Preez says.
He
says these discoveries can help to establish how the parasites developed and
how they spread across the earth over geological time, as this group of
parasites is species-specific.
He
adds that amphibians are the first group of vertebrates that moved onto dry
land, even before dinosaurs.
“The
parasites found in the group of aquatic animals consequently give us a good
indication of when this movement occurred in geological time.”
Answering
more questions
Du
Preez says the discovery of the unique parasites will be keeping scientists
very busy in months to come. He is in the process of analysing the new species
and describing them, but their research has created even more questions.
He
expects to return to the rain forests to do more research next year.
“It was an incredible place to do
research and we have been invited by the CNRS to visit the base again.”
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