Scientists at the Max Planck Institute for Developmental Biology, together with American colleagues, have decoded the genome of the Pristionchus pacificus nematode, thereby gaining insight into the evolution of parasitism.
In their work, which has been published in the latest issue of Nature Genetics, the scientists from Professor Ralf J. Sommer's department in Tübingen, Germany, have shown that the genome of the nematode consists of a surprisingly large number of genes, some of which have unexpected functions.
These include a number of genes that are helpful in breaking down harmful substances and for survival in a strange habitat: the Pristionchus uses beetles as a hideout and as means of transport, and feeds on the fungi and bacteria that spread out on their carcasses once they have died. It thus provides the clue to understanding the complex interactions between host and parasite. (Nature Genetics, Advance online publication, 21.09.2008, doi: 10.1038/ng.227)
With well over a million different species, nematodes are the largest group in the animal kingdom. The worms, usually only just one millimetre in length, are found on all continents and in all ecosystems on Earth. Some, as parasites, are major pathogens to humans, animals and plants. Within the group of nematodes, at least seven forms of parasitism have developed independently from one another. One member of the nematode group has acquired a certain degree of fame: due to its humble lifestyle, small size and quick breeding pattern, Caenorhabditis elegans is one of the most popular animals being used as models in biologists' laboratories. It was the first multicellular animal whose genome was completely decoded in 1998.
Ten years later, a group of scientists from the Max Planck Institute for Developmental Biology in Tübingen (Germany), together with researchers from the National Human Genome Research Institute in St. Louis (USA), have now presented the genome of another species of nematode, the model organism Pristionchus pacificus. Pristionchus species have carved out a very particular habitat for themselves: they live together with May beetles, dung beetles and potato beetles in order to feast on the bacteria and fungi that develop on the carcasses of these beetles after they have died. The nematodes therefore use the beetles as a mobile habitat that offers them shelter and food.
When they move from the land to the beetle, the nematodes' habitat changes dramatically. The nematodes have to protect themselves against toxic substances in their host, for example. The methods they employ to cope with the conditions in the beetle are worthy of closer attention, as this life form can possibly be regarded as the precursor to real parasites. At least, this is what researchers have suspected for a long time.
The sequencing of the genome of Pristionchus pacificus has now confirmed this suspicion: the genome, consisting of around 170 megabases, contains more than 23,500 protein-coding genes. By comparison, the model organism of Caenorhabditis elegans and the human parasite Brugia malayi (whose genome was sequenced in 2007) only have about 20,000 or 12,000 protein-coding genes, respectively. "The increase in Pristionchus is partly attributable to gene duplications," explained Ralf Sommer. "These include a number of genes that could be helpful for breaking down harmful substances and for survival in the complex beetle ecosystem."
Surprisingly, the Pristionchus genome also has a number of genes that are not known in Caenorhabditis elegans, although they have been found in plant parasites. Genes for cellulases - enzymes that are required to break down the cell walls of plants and microorganisms - have aroused particular interest among scientists. "The really exciting questions are still to come", said Sommer. "Using the sequence data, we can test how Pristionchus has adapted to its specific habitat. And this will undoubtedly give us new insight into the evolution of parasitism."
Dieterich, C., Clifton, S. W., Schuster, L., Chinwalla, A., Delehaunty, K., Dinkelacker, I., Fulton, L., Fulton, R., Godfrey, J., Minx, P., Mitreva, M., Roeseler, W., Tian, H., Witte, H., Yang, S.-P., Wilson, R. K. & Sommer R. J. (2008): The Pristionchus pacificus genome provides a unique perspective on nematode lifestile and parasitism. Nature Genetics, Advance Online Publication, September 21, 2008, doi:10.1038/ng.227.
ContactProf. Dr. Ralf J. Sommer
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences