There is a lot of mucus in the kingdom.
Amphibians, snails, and slugs are some of the more famous masters of mucus.
mucus is produced in the mouth, nose, throat, lungs, gut, and the urinary tract in our species.
The origin of the world's slimy stuff is a mystery.
Many forms of mucus have evolved in parallel and are not like a tree.
A small study has shown that many mucus genes don't share a common ancestor.
It's unusual because most genes with similar functions originate from the same ancestral genes that are passed down through the generations.
The genes that are used to make mucus are part of many families. One makes gel-forming mucus and the other makes mucus that is bound to a cell's membranes. There are genes that do not fit anywhere else.
Researchers think they have figured out where the different lineages came from.
When comparing mucus-encoding genes across 49 mammal species, the team found that when short repeated chains of amino acids are added again, non- mucin genes can evolve into slimy, mucin genes.
Random repeats were counted 15 times.
Over time, some genes in mammals that are involved in non-Mucin activities tend to be slim. The authors of the current study say that those that are rich in the organic acid proline are more likely to go gooey with the generations.
Evolutionary Biologist from the University of Buffalo, Omer Gokcumen, says that he doesn't think it was previously known that the function of a protein can evolve from one sequence to another.
Aprotein that isn't a mucin becomes a mucin by repeating. This is an important way that evolution works. We now document this happening over and over again.
When studying human saliva, the authors stumbled upon their discovery. They noticed that one of the mucin genes in humans was similar to the one in mice.
They couldn't find a common ancestry.
There is a structure in the genes responsible for human tears that isn't considered mucus.
Gokcumen thinks that the tear gene ends up being used for something else.
The repeats that give the mucin function give it the ability to be expressed in mouse and rat saliva.
If Gokcumen and his colleagues are correct, they have found a new mechanism for the formation of new genes.
This is an example of convergent evolution, where the same function in unrelated genes is created by the same pressure.
Petar Pajic is an evolutionary geneticist from the University at Buffalo.
At the other end of the spectrum, if this mechanism goes off the rails, then maybe it can lead to diseases such as cancer.
It isn't a pursuit to sniff at mucus, it's a pursuit to study it.
The study was published in a peer-reviewed journal.
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