Study discovers how beetle shells harden

Aug 05, 2005

Kansas State University researchers think their discovery of the enzyme involved in the hardening of a beetle's exoskeleton or cuticle could lead not only to better pest control, but also help create similar strong, lightweight materials for use in aircraft and armor.

After a beetle first molts, its exoskeleton is soft and hydrated. Somehow, it dries out and forms a hard, stiff exoskeleton. Since the 1940s, scientists have wondered which enzyme among several possible candidates was involved in the hardening process.

The K-State researchers have found that by knocking out an enzyme called laccase-2, cuticle tanning, the process of hardening and pigmentation, can be prevented in the red flour beetle, Tribolium castaneum.

A paper, to be released the week of Aug. 1 in the Proceedings of the National Academy of Sciences, presents the research results. The K-State researchers are Yasuyuki Arakane, research associate in biochemistry; Subbaratnam Muthukrishnan, professor of biochemistry; Richard Beeman, adjunct professor of entomology; Michael Kanost, professor and head of the department of biochemistry; and Karl Kramer, adjunct professor emeritus of biochemistry.

Kramer said K-State researchers wanted to find out what happens between the times when the cuticle is soft and when it is hard. They studied the cuticle's composition and how the components interacted to give it stiffness, flexibility and lightness. The main components in the cuticle are proteins and chitin, which also are found in crustaceans and other invertebrates.

The researchers knew one of two classes of oxidative enzymes, tyrosinases or laccases, is likely responsible for catalyzing the exoskeleton's hardening by cross-linking cuticular proteins, Kanost said.

"When we knocked out tyrosinase, everything was normal," Kramer said. "When we knocked out laccase-2, we prevented tanning from taking place."

When the laccase-2 gene was not expressed, the newly formed cuticle remained soft and white instead of becoming hard and dark-colored. These results indicated which protein was responsible for the hard shell's formation, Kanost said.

The identification of laccase-2 as the catalyst for cuticle tanning opens up possibilities of targeting this protein as a way of weakening the beetle's physical defenses against mechanical, chemical and biological injuries, Muthukrishnan said. Better insecticides could be developed as a result of having a more insect-specific target like laccase-2, Kramer said.

"Gaining knowledge about a molecular process required for insect development, but absent from humans and other vertebrate animals, such as cuticle tanning, may be useful for developing new, bio-rational methods for controlling pest insect populations," Kanost said.

Armed with this new information, a number of practical applications are possible. Materials based on the chemistry of the insect exoskeleton could be developed to make lightweight materials for aircraft and military armor, Kramer said.

"I sometimes speculate that we might help K-State coach Bill Snyder develop better football helmets and shoulder pads for his players," he said.

Collaborative research with scientists at the University of Kansas is in the beginning stages to analyze quantitatively the mechanical properties of insect cuticles and to perform cuticle protein cross-linking experiments that are catalyzed by insect laccase, Kramer said. KU scientists will test the strength of the synthetic cross-linked biopolymers that are created. This could be used for the development of strong, lightweight materials.

Both Beeman and Kramer also work at the Grain Marketing and Production Research Center, Agricultural Research Service, United States Department of Agriculture, in Manhattan.

This research has been supported by a grant from the National Science Foundation.

Source: Kansas State University

Explore further: Ancient Greek well yields rare wooden statue

add to favorites email to friend print save as pdf

Related Stories

MasterCard, Zwipe announce fingerprint-sensor card

4 hours ago

On Friday, MasterCard and Oslo, Norway-based Zwipe announced the launch of a contactless payment card featuring an integrated fingerprint sensor. Say goodbye to PINs. This card, they said, is the world's ...

Plastic nanoparticles also harm freshwater organisms

6 hours ago

Organisms can be negatively affected by plastic nanoparticles, not just in the seas and oceans but in freshwater bodies too. These particles slow the growth of algae, cause deformities in water fleas and impede communication ...

Atomic trigger shatters mystery of how glass deforms

6 hours ago

Throw a rock through a window made of silica glass, and the brittle, insulating oxide pane shatters. But whack a golf ball with a club made of metallic glass—a resilient conductor that looks like metal—and the glass not ...

US company sells out of Ebola toys

14 hours ago

They might look tasteless, but satisfied customers dub them cute and adorable. Ebola-themed toys have proved such a hit that one US-based company has sold out.

UN biodiversity meet commits to double funding

15 hours ago

A UN conference on preserving the earth's dwindling resources wrapped up Friday with governments making a firm commitment to double biodiversity aid to developing countries by 2015.

Recommended for you

US state reaches deal to keep dinosaur mummy

8 hours ago

North Dakota reached a $3 million deal to keep a rare fossil of a duckbilled dinosaur on display at the state's heritage center, where it will serve as a cornerstone for the facility's $51 million expansion, officials said ...

Jerusalem stone may answer Jewish revolt questions

11 hours ago

Israeli archaeologists said Tuesday they have discovered a large stone with Latin engravings that lends credence to the theory that the reason Jews revolted against Roman rule nearly 2,000 ago was because ...

Kung fu stegosaur

11 hours ago

Stegosaurs might be portrayed as lumbering plant eaters, but they were lethal fighters when necessary, according to paleontologists who have uncovered new evidence of a casualty of stegosaurian combat. The ...

User comments : 0