Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How stick insects handle indigestive food

10.03.2016

Plant cell walls are comprised of many complex polymers that require multiple different enzymes to fully break down, such as cellulase to digest cellulose and xylanase to digest xylan. For decades scientists thought only microbes could produce cellulase, until cellulase genes were found in wood-feeding insects. Now, new research from the Max Planck Institute for Chemical Ecology in Jena, Germany, overturns another old theory. The scientists discovered that stick insects (Phasmatodea) produce cellulases that can handle several types of cell wall polymers equally.

Cellulose as well as xylan and xyloglucan are important components of plant cell walls. All walking sticks ((Phasmatodea) inherited multiple copies of cellulase genes, whose enzymes can attack the glucose backbone of cellulose.


A young Australian stick insect (Extatosoma tiaratum) hangs upside-down on a houseplant at the Max Planck Institute for Chemical Ecology.

Matan Shelomi / Max Planck Institute for Chemical Ecology

However, some of these enzymes can also break down the xylose-backbone of xylan, and others the xylose-glucose backbone of xyloglucan. This discovery marks the first known xyloglucanase of any kind to be found in multicellular animals. Such enzymes in animals were previously not thought to exist.

One enzyme, many substrates

Researchers in the Department of Entomology isolated the cellulase genes from seven species of stick insect, including the Australian Extatosoma tiaratum, the Vietnamese Ramulus artemis, and the Bornean Aretaon asperrimus.

All express multiple different cellulase enzymes from the glycoside hydrolase family 9 (GH9). Maintaining redundant enzymes does not make sense if all have the same function, so the researchers hypothesized some had lost their function or evolved to do something new.

To test what these enzymes were capable of, the genes were expressed in a stable insect cell line, and the activities of the isolated proteins tested against different plant cell wall polymers. The results showed that one groups of enzymes were active against cellulose and xylan, and another cellulose and xyloglucan, and several in each group could also degrade glucomannan.

These abilities held in all families of stick insects, present in the Vietnamese Medauroidea extradentata (Family Phasmatidae), the Madagascan Sipyloidea sipylus (Diapheromeridae), and the Peruvian Peruphasma schultei (Peruphasmatidae). The researchers even got samples of the Californian Timema cristinae (Timematidae), considered the sister group to all other Phasmatodea, and found the same enzymes with the same new abilities.

Such multifunctionality is almost unheard of from glycoside hydrolases 9, and xyloglucanases of any family were never discovered in animals before. “If we hadn’t tested these enzymes on other substrates besides cellulose, there was no way we could have discovered these functions,” said Dr. Matan Shelomi, a postdoctoral fellow at the Max Planck Institute for Chemical Ecology and lead author of the study. “It was good that we did: nobody found these kind of powerful enzymes in an animal before.”

A new twist on an old gene family

Most importantly, the enzyme functions matched the evolutionary relationships between the insects. Xylanase-cellulases from different species were closely related, and the xyloglucanase-cellulases also formed a monophyletic group. Because T. cristinae also had these activities, this means an ancestral, insect cellulase gene duplicated into several genes, some of which were then able to evolve new abilities. This happened before the Phasmatodea evolved. Next the researchers are testing other insects related to the stick insects, to see if they have multifunctional cellulases too.

The ability to break down different polymers with the same enzymes means the Phasmatodea gut is unusually efficient. Along with other enzymes such as cellobiases and xylobiases, their guts can fully degrade nearly all the plant cell wall into its component sugars, using them for nutrition as well as having more access to the easily digested cytoplasm within the cells.

This means they can derive more nutrition from the same leafy diet than other herbivores. Theoretically, they could even digest wood. “There is a big community in Germany of people with stick insects as pets,” says Shelomi, “and they report them nibbling on sticks, moss, bark, and even Styrofoam and electric cables… but leaves are still their main food. Maybe their gut can break down wood, but their jaws are better suited for leaves, which probably taste better too.” [MS]

Original Publication:
Shelomi, M., Heckel, D. G., and Pauchet, Y. (2016). Ancestral Gene Duplication Enabled the Evolution of Multifunctional Cellulases in Stick Insects (Phasmatodea). Insect Biochemistry and Molecular Biology 71: 1-11. Doi: 10.1016/j.ibmb.2016.02.003
http://dx.doi.org/10.1016/j.ibmb.2016.02.003

Further Information:
Dr. Matan Shelomi, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, Germany, Tel. +49 3641 57-1560, E-Mail mshelomi@ice.mpg.de

Contact and Media Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, E-Mail overmeyer@ice.mpg.de

Download high-resolution images via http://www.ice.mpg.de/ext/downloads2015.htm

Weitere Informationen:

http://www.ice.mpg.de/ext/1260.html?&L=0 (How stick insects handle indigestive food)
http://www.ice.mpg.de/ext/655.html (Project Group "Molecular Biology of the Insect Digestive System")
http://www.ice.mpg.de/ext/entomology.html?&L=0 (Department of Entomology)

Angela Overmeyer | Max-Planck-Institut für chemische Ökologie

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>