Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

With toxic crystals, bacterium targets - and takes out nematodes

06.03.2003


Long-time farmers’ friend shows promise against parasitic worms



Roundworms, hookworms, watch out. Scientists this week announced that a soil bacterium’s crystal proteins, long an effective weapon against many insect pests, are toxic to some nematodes, too.

The crystal proteins - created by some strains of Bacillus thuringiensis, more commonly known as Bt - thwart the development of some nematodes and kill others outright. The findings raise the possibility that these proteins might one day be used to combat parasitic worms that infect nearly one-fourth of the world’s human population. Nematodes - unsegmented, long, round worms pointed at both ends - are responsible for illnesses that can lead to elephantiasis of the limbs, intestinal lesions, a type of meningitis and "river blindness."


Led by biologist Raffi V. Aroian of the University of California San Diego, a team of researchers examined the impact of seven different Bt toxins upon six different nematode species, including one intestinal parasite. Funded by the National Science Foundation (NSF), the research appears in the March 4 journal Proceedings of the National Academy of Sciences (PNAS) and is available in the journal’s online "early edition" at www.pnas.org.

The crystals, of which there are many variations, form from the aggregation of proteins that are produced as the bacillus makes spores. Individually, their toxicity is very species-specific, and more than 150 insect species are known to be susceptible to one type of Bt crystal or another. However, the crystals are harmless to humans and to natural enemies of many crop pests.

(For more about Bacillus thuringiensis, visit the Aroian lab’s web site at www.btcrystal.org.)

Nematodes, relatively simple anatomically and genetically, are found in nearly every environment. Among the more than 100,000 known species are plant parasites, such as roundworms; animal parasites, such as hookworms and heartworms; and insect pathogens. Most are shorter than short-grained rice. Some, particularly those found in the relative comfort of another organism’s gut, can reach lengths of several meters, including one in sperm whales that measures upwards of 13 meters long. Many feed on bacteria.

Applying an array of crystal proteins from Bt to a diverse group of five small, free-living nematodes, Aroian’s group found that each worm species tested was susceptible to at least one of the toxins. The scientists also found that three of the Bt crystals were effective in crippling the free-living stage of a worm (Nippostrongylus brasiliensis) that spends its parasitic days in rats’ guts.

Represented in the study were two "largely unstudied classes of crystal proteins," one of which is closely related to those long in use as organic insecticides. Their effectiveness known for nearly a century and first approved for use in the United States in 1961, these Bt insecticides kill crop-killing caterpillars and beetles, and disease-transmitting black flies and mosquitoes.

According to the PNAS report, "The success of these toxins is due in large part to their high toxicity towards insects but no/low toxicity toward other animals. They have an excellent track record in over 50 years of use by organic and conventional farmers."

The researchers found that the Bt crystal proteins’ "toxicity in nematodes correlates with damage to the intestine, consistent with the mechanism of crystal toxin action in insects," leading them to question whether the worms, not insects, may be the natural primary target of the soil-dwelling bacterium’s toxin.

"It is puzzling why a bacterium that is so ubiquitously found in the soil might have evolved ingestible toxins to target insects that may spend little time feeding in the soil," they write. "On the other hand, there are estimated to be more than 100,000 species of nematodes, many of which live in the soil and ingest bacteria. Could nematodes be a prime target for Bt and its crystal proteins?"

According to Rita Teutonica, a genetics program director at NSF, "This report complements Aroian’s current exploration into the genetics of resistance to Bt toxins in the nematode Caenorhabditis elegans (a widely used model organism for research). More broadly, it also illustrates how inquiries into basic genetic mechanisms may ultimately lead to answers with profound worldwide benefits."

NSF Science Expert:
Rita Teutonico
Phone:(703) 732-8439
Email: rteutoni@nsf.gov

Sean Kearns | NSF
Further information:
http://www.pnas.org.
http://www.btcrystal.org.

More articles from Agricultural and Forestry Science:

nachricht Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University

nachricht New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>