Many plant-feeding insects need microbial enzymes, such as pectinases, that degrade plant cell walls; yet some insects have overcome this dependency in a surprising way. Researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, found that stick insects make microbial enzymes themselves. From an ancestral gut microbe, the genes for the essential enzymes simply “jumped” as they are to their insect host.
Many animals depend on their microbiome to digest their food. Symbiotic microorganisms produce enzymes their hosts cannot, and these work alone or together with the animals’ own enzymes to break down their food.
Many plant-feeding insects need microbial enzymes, such as pectinases, that degrade plant cell walls; yet some insects have overcome this dependency in a surprising way. Researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, found that stick insects make microbial enzymes themselves.
From an ancestral gut microbe, the genes for the essential enzymes simply “jumped” as they are to their insect host. The researchers report this newly discovered “horizontal gene transfer” in a paper recently published in Scientific Reports. (Scientific Reports, May 2016, DOI: 10.1038/srep26388)
“Insects are not supposed to make their own pectinases,” explains Dr. Matan Shelomi, a postdoctoral fellow in the Department of Entomology and lead author of the study. Yet the stick insects make lots, and their genome contains multiple pectinase genes!”
Based on DNA similarity, the source was a gamma-proteobactera, the most common bacteria type in the stick insect microbiome, but commonly found on the leaves they eat too. “We are not sure how it happened, but one or two pectinase genes from a gut bacterium or even just something in the food clearly jumped into the stick insect genome, and then evolved along with the insects,” explains Shelomi. Tests show some of the new pectinases retained their original job degrading pectin, while others have yet unknown functions. But when did the transfer happen?
An international collaboration solves the puzzle
To find out, the team first tested seven different species of stick insect, including a primitive and short species found only in California called Timema cristinae, in the sister group to all the other stick insects. Timema do not have pectinases, while the others, the “Euphasmatodea,” do. It was not clear, however, whether Timema never had the genes or simply lost them. The team then collaborated with the 1K Insect Transcriptome Evolution Project (http://www.1kite.org/). Using 1KITE’s genetic databases from 1000 insect species, including nearly 50 Phasmatodea, the researchers could quickly search multiple groups for these enzymes. The results showed that the gene jump occurred sometime after Timema and Euphasmatodea split, but before the latter diverged into the 3000 or so species it has today: between 110 to 60 million years ago.
Gut microbe genes can change their hosts
Other researchers in the Department of Entomology previously discovered horizontal pectinase transfers in leaf beetles. It may not be a coincidence that these and the stick insects are all specialists on leaves. Nor is it necessarily coincidence that each group experienced a massive species radiation after their horizontal transfer occurred. “Something happened, to make the tiny Timema become a planet-wide group of nearly 3000 species that can be nearly half a meter long,” says Shelomi, referring to the world’s longest insect, a Euphasmatodea called Phoebetica chani. His new theory, the Enzyme Expansion Hypothesis, is that the sudden appearance of new enzyme abilities, either through mutation or horizontal gene transfer, can drive the evolution of a species and change their diets to specialize on a single food source.
Beyond enzymes, horizontal gene transfer can provide any number of new abilities, and our microbiome provides an immense source of potential species-altering proteins. “The idea that genes from microbes living in our guts can suddenly become part of our genomes and change the course of our evolutionary history, that’s an incredible finding,” Shelomi concludes. [MS/AO]
Shelomi, M., Danchin, E. G. J., Heckel, D. G., Wipfler, B., Bradler, S., Zhou, X., Pauchet, Y. (2016). Horizontal gene transfer of pectinases from bacteria preceded the diversification of stick and leaf insects. Scientific Reports, 6: 26388. doi:10.1038/srep26388.
Dr. Matan Shelomi, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, Germany, Tel. +49 3641 57-1560, E-Mail firstname.lastname@example.org
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 email@example.com
Download high-resolution images via http://www.ice.mpg.de/ext/downloads2016.html
Angela Overmeyer | Max-Planck-Institut für chemische Ökologie
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
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...
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...
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...
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....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences