The findings suggest a way to rescue "doomed" animal hybrids.
Genetic "dark matter" may drive the emergence of new species, new research finds. These long, repeating stretches of the genome, called satellite DNA, may ultimately prevent incompatible animals from mating by scrambling the chromosomes in their hybrid babies, according to the study. And if animals from different populations can't mate, they will diverge over time, leading to speciation. Just 1% of the 3 billion letters, or nucleotides, in the human genome make the proteins that determine traits such as eye color and height. Other stretches of DNA may tell the body how many copies of a protein to make, or turn genes on or off in different tissues, among other functions. Yet nearly 10% of the human genome is composed of long, repeating stretches of satellite DNA that, for many years, scientists didn't think did much of anything, said study co-author Madhav Jagannathan, currently an assistant professor at the ETH Zurich Institute of Biochemistry in Switzerland. "Satellite DNA repeats were very abundant in species and widely observed in eukaryotes," or life-forms with cell nuclei, Jagannathan told Live Science in an email. "Despite this, they were largely dismissed as junk DNA." However, in a 2018 study, Jagannathan, who was then at the Massachusetts Institute of Technology (MIT), and his former postdoctoral adviser, biologist Yukiko Yamashita, also at MIT, discovered that some of this DNA served a critical purpose: It organizes DNA within a cell's nucleus. That study found that certain proteins grab DNA molecules and arrange them in densely packed bundles of chromosomes called chromocenters. Satellite DNA, they found, tells these grabby proteins how to bundle and organize chromosomes. Read more...
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