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Category: biotech/medical – Page 1587

Viruses are tiny invaders that cause a wide range of diseases, from rabies to tomato spotted wilt virus and, most recently, COVID-19 in humans. But viruses can do more than elicit sickness — and not all viruses are tiny.

Large viruses, especially those in the nucleo-cytoplasmic large DNA virus family, can integrate their genome into that of their host — dramatically changing the genetic makeup of that organism. This family of DNA viruses, otherwise known as “giant” viruses, has been known within scientific circles for quite some time, but the extent to which they affect eukaryotic organisms has been shrouded in mystery — until now.

“Viruses play a central role in the evolution of life on Earth. One way that they shape the evolution of cellular life is through a process called endogenization, where they introduce new genomic material into their hosts. When a giant virus endogenizes into the genome of a host algae, it creates an enormous amount of raw material for evolution to work with,” said Frank Aylward, an assistant professor in the Department of Biological Sciences in the Virginia Tech College of Science and an affiliate of the Global Change Center housed in the Fralin Life Sciences Institute.

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In their paper published in Frontiers of Physics, Franco Vazza (astrophysicist at the University of Bologna) and Alberto Feletti (neurosurgeon at the University of Verona) investigated the similarities between two of the most challenging and complex systems in nature: the cosmic network of galaxies and the network of neuronal cells in the human brain.

Despite the substantial difference in scale between the two networks (more than 27 orders of magnitude), their quantitative analysis, which sits at the crossroads of cosmology and neurosurgery, suggests that diverse physical processes can build structures characterized by similar levels of complexity and self-organization.

The human brain functions thanks to its wide neuronal network that is deemed to contain approximately 69 billion neurons. On the other hand, the observable universe can count upon a cosmic web of at least 100 billion galaxies. Within both systems, only 30% of their masses are composed of galaxies and neurons. Within both systems, galaxies and neurons arrange themselves in long filaments or nodes between the filaments. Finally, within both systems, 70% of the distribution of mass or energy is composed of components playing an apparently passive role: water in the brain and dark energy in the observable Universe.

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Circa 2013

The Book of Genesis puts Adam and Eve together in the Garden of Eden, but geneticists’ version of the duo — the ancestors to whom the Y chromosomes and mitochondrial DNA of today’s humans can be traced — were thought to have lived tens of thousands of years apart. Now, two major studies of modern humans’ Y chromosomes suggest that ‘Y-chromosome Adam’ and ‘mitochondrial Eve’ may have lived around the same time after all1, 2.

When the overall population size does not change (as is likely to have happened for long periods of human history), men have, on average, just one son. In this case, evolutionary theory predicts that for any given man there is a high probability that his paternal line will eventually come to an end. All of his male descendants will then have inherited Y chromosomes from other men. In fact, it is highly probable that at some point in the past, all men except one possessed Y chromosomes that by now are extinct. All men living now, then, would have a Y chromosome descended from that one man — identified as Y-chromosome Adam. (The biblical reference is a bit of a misnomer because this Adam was by no means the only man alive at his time.)

Similarly, the theory predicts that all mitochondrial genomes today should be traceable to a single woman, a ‘mitochondrial Eve’. Whereas the Y chromosome is passed from father to son, mitochondrial DNA (mtDNA) is passed from mother to daughter and son.

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Circa 2013

A group of scientists from Kyoto has managed to successfully analyze and “record” the basic elements of what people see when they dream. The idea of recording dreams has been a mainstay in science fiction, but also a frequent goal for researchers. As Smithsonian Magazine writes, this group designed its study based on the premise that brains react to “seeing” objects with repeatable patterns that can be measured with MRI. If a machine can recognize the patterns well enough, it can reverse-engineer them, giving us a window into what’s going on inside people’s heads while they dream.

Three participants were selected for a study and asked to sleep for several three-hour blocks in an MRI scanner. Once they fell asleep, scientists woke them up and asked them to describe what they’d seen in the dream, grouping them into loose categories and sub-categories like “car,” “male,” “female,” or “dwelling.” The group then picked representations of those categories from an online image search and showed them to the participants, once again measuring their brain activity to figure out what patterns might be unique to that concept. Finally, the participants were asked to sleep again, but this time, a machine wouldn’t simply record how their brain responded to dreaming — it would attempt to match it to one of the categories with a series of images, as seen in the video below.

When matching the contents of the video to the categories the sleeper actually recounted when asked about a dream, the machine turned out to be right roughly 60 percent of the time, or better than it could have done by random chance. The system was unsurprisingly better at detecting general meta-categories, like whether someone was looking at a person or a scene, than it was at sensing more specific objects.

Continue reading “Scientists turn dreams into eerie short films with an MRI scan” | >