In a computer-based search for pieces of DNA that have undergone the most change since the ancestors of humans and chimps diverged, "Human Accelerated Region 1" or HAR1, was a clear standout, said lead author Katie Pollard, assistant professor at the UC Davis Genome Center and the Department of Statistics.
"It's evolving incredibly rapidly," Pollard said. "It's really an extreme case."
As a postdoctoral researcher in the lab of David Haussler at UC Santa Cruz, Pollard first scanned the chimpanzee genome for stretches of DNA that were highly similar between chimpanzees, mice and rats. Then she compared those regions between chimpanzees and humans, looking for the DNA that, presumably, makes a big difference between other animals and ourselves.
HAR1 has only two changes in its 118 letters of DNA code between chimpanzees and chickens. But in the roughly five million years since we shared an ancestor with the chimpanzees, 18 of the 118 letters that make up HAR1 in the human genome have changed.
Experiments led by Sofie Salama at UC Santa Cruz showed that HAR1 is part of two overlapping genes, named HAR1F and HAR1R. Evidence suggests that neither gene produces a protein, but the RNA produced by the HAR1 sequence probably has its own function. Most of the other genes identified by the study also fall outside protein-coding regions, Pollard said.
Structurally, the HAR1 RNA appears to form a stable structure made up of a series of helices. The shapes of human and chimpanzee HAR1 RNA molecules are significantly different, the researchers found.
RNA is usually thought of as an intermediate step in translating DNA into protein. But scientists have begun to realize that some pieces of RNA can have their own direct effects, especially in controlling other genes.
The proteins of humans and chimps are very similar to each other, but are put together in different ways, Pollard said. Differences in how, when and where genes are turned on likely give rise to many of the physical differences between humans and other primates.
Researchers at UC Santa Cruz, the University of Brussels, Belgium and University Claude Bernard in Lyon, France, showed that HAR1F is active during a critical stage in development of the cerebral cortex, a much more complicated structure in humans than in apes and monkeys. The researchers found HAR1F RNA associated with a protein called reelin in the cortex of embryos early in development. The same pattern of expression is found in both humans and rhesus monkeys, but since the human HAR1F has a unique structure, it may act in a slightly different way. Those differences may explain some of the differences between a human and chimp brain.
Andy Fell | EurekAlert!
Making fuel out of thick air
08.12.2017 | DOE/Argonne National Laboratory
‘Spying’ on the hidden geometry of complex networks through machine intelligence
08.12.2017 | Technische Universität Dresden
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications
Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...
Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.
The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...
08.12.2017 | Event News
07.12.2017 | Event News
05.12.2017 | Event News
11.12.2017 | Physics and Astronomy
11.12.2017 | Materials Sciences
11.12.2017 | Earth Sciences