Just like unnecessary outtakes from a movie, certain sequences in our genes are wasted, not being used by cells to make proteins. Despite this, two studies show that non-coding segments - called "introns" - help yeast get through hard moments of their existence while certain stress is exerted by its environment.
Scott Roy at San Francisco State University of California - not connected to the study - underlines that the research opens a whole new paradigm concerning what introns could be capable of.
Guillaume Chanfreau, a yeast microbiologist at the University of California, Los Angeles, states that the research explains why yeast has retained what had previously been regarded as non-protein-coding "junk DNA" and, therefore, useless.
Introns are common in plants and fungi, as well as in people and other animals.Each of the 20,000 genes we carry contains eight non-coding sequences on average.And, each time one of our cells begins to make a protein out of a given gene, our enzymes generate a RNA copy that also includes the introns.Consequently, the cell destroys the RNA-contained introns and combines the remaining parts together.The such-prepared RNA sequence serves as a particular guide for building the protein.
The removal of introns requires a large quantity of energy, as well as a complex set of molecular shears. This suggests that such sequences have evolved to perform certain functions.Initially, they would be treated as "junk", while researchers have recently started to identify their untypical roles.For example, in the case of certain genes, introns may help control the quantity of proteins a given cell manufactures.
However, when it comes to baker's yeast, the functions of most of such sequences are unclear.First, scientists would methodically remove introns from yeast, such producing hundreds of strains, each being devoid of all non-coding sequences from one gene.Next, the researchers bred combinations of the modified strains in parallel to normal fungi.Finally, it turned out that most strains lacking introns promptly died out in rough environmental conditions, as they could not compete with normal yeast.Still, they could do significantly better when there was no shortage of nutrients in other respective environments.
Jeffrey Morgan, a former student of Bartel and currently a molecular biologist at the University of Utah in Salt Lake City, says it was unusually peculiar.The Bartel's group - just like Abou Elela's one - discovered that introns help yeast survive throughout environmental stress, being detrimental to ones living under more advantageous conditions.It is still unclear whether such a correlation also exists in the case of humans.