Scientists have recently discovered that a particular species of worm commonly seen living on scarab beetles tend to eat its own kind-- except its relatives.
This particular nematode is called Pristionchus pacificus. In an experiment, scientists saw how this nematode engage in cannibalism, but knows how to tell its family apart.
How Do The Nematodes Do It?
Cannibalism is actually quite common in the animal kingdom, but seeing self-recognition from nematodes is actually quite baffling to scientists. An experiment was performed to see how these worms manage to avoid their offspring or close relatives in a hunger spree, and they discovered that a particular gene called SELF-1 is responsible for this phenomenon.
First, the researchers tried to see if the scent is a major factor for these nematodes to distinguish one another. They tried to blend the scent of some close-knit nematodes with another species, but to their surprise, the nematodes still managed to tell they are family.
The scientists then dug deeper and deduced that they need to look closely into the genetic differences between the different strains of the pacificus nematode. They discovered a region in the genome linked with the killing tendencies.
They used CRISPR-Cas9 to recognize the gene responsible for the nematode's self-recognition. The sequence of this gene was then changed through gene editing, and by only then did the nematodes start eating their own family.
The SELF-1 Gene
This gene is called SELF-1, and it acts as a sort of a calling card or ID among all nematodes to distinguish whether they're family or not. Each gene strain is unique, giving the nematodes no trouble in identifying their kin. It's located on the outermost layer of the skin, which means nematodes need the sense of touch to discern if their fellow nematode is safe to eat.
Although the scientists discovered this breakthrough, they still have a few questions they need answers to. What kind of molecular mechanism is responsible for the unique strains of SELF-1? How do the nematodes detect this kind of signal with the use of touch?
The scientists are keen to undergo more research to understand this surprising phenomenon, and in the future, they hope to discover the evolutionary path of these divergent strains and to shed light on the other self-recognition systems in other species.