For some time, the new "super tool" of genetic engineering has repeatedly caused a stir: With the Genscher Crispr / Cas9 interventions in the genome are comparatively easy and accurate. The system, copied from nature, finds every desired location in the genome and allows manipulation there. Using the Crispr / Cas9 method, it is possible to insert gene fragments, correct problematic mutations and also cut away certain DNA sequences.
There is enormous potential for medical research in Crispr / Cas9, for example to eliminate genetic defects. But even in basic research, the tool is now in use: It has revolutionized the possibilities of investigating the function of certain genes. In simple terms, researchers use Crispr / Cas9 to cut out a particular gene and then investigate what effect this genetic loss has on an organism.
Special ant species make it possible
Exactly this system has now been harnessed by two research teams that are on the track of the genetic basis of the complex social behavior of ants. The group around Daniel Kronauer of Rockefeller University in New York used the unusual ant species Ooceraea biroi for their Crispr / Cas9 experiments. In this species, there are no queens that provide the egg production by sexual means. The insects instead multiply by unfertilized eggs that develop into clones. In this concept, known as parthogenesis, ant colonies emerge in which the individuals are genetically identical. "This means we can use Crispr / Cas9 to modify individual eggs to build a colony that has the complete gene mutation we want to study, " explains Kronauer.
The second team around Claude Desplan of New York University, however, used the ant species Harpegnathos saltator for their Crispr / Cas9 experiments. It also offers a special way of manipulating entire races: when the queen dies in this species, young worker ants can become "pseudo-queens". If they are genetically modified, they pass on the manipulation to their offspring and so also creates a completely genetically modified ant colony. display
How do odourless ants behave?
According to their current research, both research groups initially targeted the same gene: the genetic material for the so-called odorant receptor coreceptor (Orco). The gene ultimately allows the training of the total of 350 ant-odor receptors of the ants. By means of Crispr / Cas9 and their special experimental animals, both research teams were able to eliminate this gene in all individuals of their experimental colonies. Ultimately, the ants were odor-blind. In this way, the researchers were able to investigate in detail what meaning the sense of smell or the perception of pheromones has on insects.
It turned out that the ants with the circumcised scent system lost their social skills and could no longer communicate with nestmates. Even the ant roads, which are based on the effect of pheromones, they could no longer follow and wandered aimlessly. In addition, switching off the Orco gene had an effect on the brain anatomy of both ant species, the researchers report. Just as humans have specialized brain regions for functions such as speech and facial recognition, ants have brain centers responsible for the perception and processing of odors. Exactly these areas were largely absent in the experimental animals, the researchers noted. What leads to this effect, they now want to investigate further.
"Our studies are proof of the feasibility of genetic studies on ants, " summarizes Kronauer. "Now we can experimentally turn off any gene we think affects social behavior and then observe its effects, " says the scientist. Shelley Berger, a researcher with Desplan's group, emphasizes that this research is not only interesting for the understanding of ant behavior, but also for the foundations of human effects: "Better understanding of how behaviors evolve could provide insight into disorders which changes in social communication are a hallmark, such as schizophrenia or depression, "says Berger.
- Cell Press