A running wolf, a flying bat, and a swimming dolphin seem to have little resemblance. But these wildly different animals are among at least 240 species of mammals, including humans, who share exactly 10% of his genome. The discovery includes more than 400,000 unidentified stretches of DNA that likely control how genes (segments of genetic material that code for proteins) actually function.The newly analyzed regions were highlighted in a paper published today chemistry We detail our first effort to directly compare 240 mammalian genome sequences. A new collaborative database called Zoonomia has also identified parts of the DNA code that give some mammals extraordinary abilities, such as hibernation and the ability to smell miles away.
To date, most studies examining mammalian genomes have used the human genome as a reference to understand how the genomes of animal species combined and evolved. But this measuring stick is only useful if the sequence of her DNA in humans is similar to that of animals. Genetic similarity to humans may not exist in animals with specific non-human adaptations or traits, such as hibernation.
To circumvent this problem, dozens of researchers in the Zoonomia project, led by Elinor Karlsson, a genomicist at the Broad Institute at the Massachusetts Institute of Technology and Harvard University, and Kerstin Lindblad-Toh at Uppsala University, Sweden, tested 240 mammals. We have collected the genome sequences of Species include humans and her two breeds of domestic dogs. They and their collaborators ran these through an algorithm that compared all genomes to each other.
Aligning the genomes in this way allowed researchers to find similarities and differences between species. For example, some bat species hibernate like bears, while other closely related bat species do not. Genome alignments have revealed DNA regions shared only among bears, hibernating bats, and other hibernating animals. These regions contained genes involved in thermoregulation, metabolism and repair of damaged neurons.
Researchers also found similarities between animal species with strong senses of smell. They found that rodents tended to have the most genes for olfactory receptor proteins that pick up odors. But even the Central American agouti, the most olfactory rodent, had fewer olfactory genes than the other three species. With 4,199 olfactory genes, African savannah elephants have more genes than any other animal. The researchers also found that animals that live alone tend to have more olfactory genes than those that live in groups. This may be because solo animals cannot rely on mate networks for warning and therefore need better abilities to sense predators and prey.
By comparing 240 genomes, researchers were able to identify which regions of the DNA code were identical across mammalian species. These conserved regions are likely to be of great importance for mammalian survival.
Previous estimates suggested that only 3% of the human genome is similar to all other mammalian genomes. But when Zoonomia’s team searched for similarities, they found that 10.7% of his human genome resembles his fellow mammals. And surprisingly, only 20% of these conserved regions were in protein-coding genes. Most of the conserved regions are in other regions of the chromosome and may influence how different genes are turned off or on, or how they are activated. These so-called regulatory elements can influence gene expression in different ways. For example, it bends DNA strands to help the cellular machinery bind to genes and ultimately create more proteins.
Researchers found 423,586 potential regulatory elements. This is called the unannotated intergenic restricted region (UNICORN). Many of these are located near genes that influence how animals interact with their environment, such as skin development and ability to adapt to change. Lindblad-Toh says it is almost certain that UNICORN affects gene regulation in ways that are not yet understood.
These UNICORNs have never been identified, even by large scientific collaborations that probed hundreds of thousands of human genomes. “We didn’t need perfection. We needed a large number of species to compare with each other,” says Karlsson.
David Kingsley, a developmental biologist at Stanford University, who wasn’t involved in the study, says that at least as a first step, aligning genomes rather than studying each species individually will help to improve the genetics and biology of species. can reveal much more about “It draws on a far broader set of experiments in nature than those conducted by humans,” he says. He hopes that biologists will use this information to delve further into the regulatory DNA important in defining species behavior and adaptation.
According to Karlsson, the current challenge is to better understand the physiology and behavior of animal species and better identify their genetic similarities. “Somebody has to study her 240 species to see how big her brain is to see if it hibernates,” she says. She and her Lindblad-Toh plan to add more primate genomes to the database. This will allow us to more accurately determine how humans evolved. But the most important discoveries will come when other researchers start studying the genetics of their favorite species, they say. Zoonomia databases can fill many gaps, especially those that are not internal to genes, and allow scientists to ask new questions.
“It’s a really great resource they’ve created,” says Nathan Clarke, an evolutionary genomicist at the University of Utah. He was not involved in this research. He says the database will be useful to groups like him who are interested in specific species and traits such as long lifespans, extraordinary vision, and the ability to live at high altitudes. “This is just the beginning,” says Clark.
