In research published in the journal Proceedings of the National Academy of Science, scientists have found that Photorhabdus bacteria produce an antibiotic which inhibits the work of an enzyme that insects’ immune systems use to defend themselves from attack.
Although such so-called gene-for-gene interactions are thought to be common in diseases, very few examples of a single gene in a pathogen targeting a single gene in an animal or human host have been identified so far.
Photorhabdus is a family of bacteria that in relatively small concentrations can kill insects - between 10-100 cells of it are typically enough – but most are harmless to humans and can be used as a biological control mechanism to replace pesticide use.
The researchers, from the universities of Bath, Bristol and Exeter, all in the UK, used the large caterpillar Manduca sexta (tobacco hornworm) to study the bacteria’s so-called virulence genes.
“The beauty of this research is that we have been able to study the whole genome of the bacteria to work out how it kills its host,” said Professor Stuart Reynolds from the University of Bath.
“People studying diseases think that the kind of gene-for-gene interaction between pathogen and host that we have found is quite common, but actually rather few are known, which is why this research is so interesting.
“The immune systems of all animals, even relatively simple ones like insects, are all very similar.
“This is particularly true of the innate immune system, which is the fast-acting battery of defences that recognise and kill microbes to prevent infections from occurring.
“Some remarkable discoveries have been made using insects that have subsequently allowed important advances in understanding how the human immune system works.”
As part of their innate immune system, insects use an enzyme called phenoloxidase to produce reactive molecules that kill bacteria and then encapsulate them in a dense coat of black pigment called melanin.
The researchers found that Photorhabdus produces a special phenoloxidase inhibitor to protect itself against this particular defence.
They identified the inhibitor as a small molecule called 1,3-dihydroxy-2-(isopropyl)-5-(2-phenylethenyl)benzene, known as ST for short.
This molecule is also an antibiotic and Photorhabdus produces it to kill off other microbes that might grow in the corpse of the dead insect.
To test their findings, the researchers produced a mutant Photorhabdus that is unable to make ST. Without ST, the bacteria were less virulent. The researchers then used a technique known RNA interference to prevent the insects from producing the phenoloxidase enzyme. These insects were more susceptible to regular Photorhabdus bacteria.
But when the two were combined, it was found that not being able to produce ST made no difference to Photorhabdus when colonising insects unable to produce phenoloxidase.
“This is conclusive evidence for a gene-for-gene interaction between the bacterium and the insect,” said Richard ffrench-Constant (correct) of Exeter University.
“Photorhabdus is an important biocontrol organism that is used to control insect pests and reduces pesticide use, so the more we know about it, the more useful it can be.
“Insects are the major players in almost every ecosystem on the planet, so we need to know as much as we can about them.”
The research was supported through the Exploiting Genomics initiative funded by the Biotechnology & Biological Sciences Research Council (UK).
Andrew McLaughlin | alfa
How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH
A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology