The cerebellum may do a lot more than just coordinate movement

Its name means “little brain” in Latin, but the cerebellum is anything but. The fist-sized orb at the back of the brain has an outsized role in social interactions, a study in mice suggests.

Once thought to be a relatively simple brain structure that had only one job, coordinating movement, the cerebellum is gaining recognition for being an important mover and shaker in the brain.

Early clinical observations of people with movement disorders pigeonholed the cerebellum, says neuroscientist Kamran Khodakhah of Albert Einstein College of Medicine in New York City. But the “cerebellum has more than half of the neurons in your entire brain,” he says. “It never made sense that the only thing it confines itself to do is motor coordination.” <!--more-->

Khodakhah’s new results on social behavior, described in the Jan. 18 Science, expand that view, and add to other work on the cerebellum’s role in memory, language and emotions. The results also offer clues to disorders such as autism and schizophrenia, both of which have been linked to an abnormal cerebellum.


By finding a connection between the cerebellum and a part of the brain involved in social behavior, Khodakhah and his colleagues “solve an important gap in our understanding of the circuitry underlying disorders such as autism and schizophrenia,” says pediatric neurologist and developmental biologist Mustafa Sahin of Boston Children’s Hospital. “We’ve known for a while that the cerebellum is involved in these disorders, but we really haven’t been able to connect it to other regions directly.”


Khodakhah and his colleagues went looking for connections to one such region — an area in the middle of the brain called the ventral tegmental area, or VTA, that’s heavily involved in feeling the thrill of reward. Using molecular tools that light up certain cells with fluorescent proteins, the researchers saw that nerve cells, or neurons, from the cerebellum sent message-sending axons directly to cells in the VTA in mice.

Not only were those connections there, they were important. Khodakhah and his colleagues used a method called optogenetics to control the activity of cerebellar nerve cells that sent messages to the VTA. Activating these cells made mice feel good, the researchers found. When the mice learned that the cells were turned on only when the animals were in a certain spot, the mice spent more time there.

These cells seem to be sending a particular sort of feel-good signal, one that comes from social interactions. The team found that the cells were active when mice were in contact with a companion. When the researchers artificially turned these cells off using lasers, mice no longer preferred to hang out with a fellow mouse over an empty room, instead spending equal amounts of time in the two areas. That social deficit suggests that this particular neural highway is involved in social behavior, Khodakhah says.


Linking the cerebellum to social behavior might also help explain some connections with autism. Damage to the cerebellum is known to increase the risk of autism, a disorder that comes with social deficits. Sahin has found some deficits in the cerebellar cells of patients with a certain form of autism. The newly described pathway, from cerebellum to the VTA, “adds to our understanding of the circuitry of social behavior and reward behavior in a very important way,” Sahin says.


The cerebellum has other jobs, too, says neurologist Jeremy Schmahmann of Massachusetts General Hospital in Boston, who has studied the brain structure for decades. Along with movement problems, people with damage to the cerebellum can have trouble with memory, planning, multitasking, creativity and language, he says. That constellation of symptoms, called cerebellar cognitive affective syndrome, shows that the cerebellum has wide-ranging jobs in the brain, Schmahmann says.
An example comes from experiments published in 2018 in NeuroImage, which show that the cerebellum is important for recognizing emotions. When researchers interfered with the structure using strong magnets, people grew worse at seeing emotions on other people’s faces.


Those results add to the growing realization that the cerebellum might have its hands in many aspects of the brain. Based on the growth of the field, these expanded roles for the cerebellum are “not unexpected, but almost required,” Schmahmann says.


source : https://www.sciencenews.org/article/cerebellum-may-coordinate-more-than-just-movement?tgt=nr

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A CRISPR gene drive for mice is one step closer to reality

Scientists are getting closer to creating a genetic pest-control measure against rodents.
Female mice engineered to carry a genetic cut-and-paste machine called a gene drive may be able to pass a particular version of one gene on to more than 80 percent of their offspring, researchers report January 23 in Nature. That rate would beat the usual 50 percent chance of handing down a gene variant, first reported in 1865 by Gregor Mendel from his studies of peas.


“What we’ve done is engineered a gene that can be inherited more frequently than it would be by normal Mendelian inheritance,” says Kimberly Cooper, a developmental geneticist at the University of California, San Diego. “My graduate student likes to call it ‘cheating Mendel.’”


Such engineered genetic cheats have been proposed to wipe out disease-carrying mosquitoes and invasive species by targeting genes involved in reproduction (SN: 12/12/15, p. 16). Gene drives might also be used to prevent pests from carrying diseases, such as malaria (SN: 12/26/15, p. 6). Researchers have made successful gene drives in laboratory experiments in mosquitoes, fruit flies and yeast.


But no one has yet built one that works in a mammal. And Cooper isn’t claiming to have done so either. By definition, a gene drive must cheat Mendelian inheritance rules over multiple generations, spreading itself to an entire population. Cooper’s group has produced one generation of genetic cheater mice, but hasn’t yet tracked the gene drive’s spread through multiple generations.
“It’s the prototype experiment you need for a drive in rodents,” says Thomas Prowse, a population ecologist at the University of Adelaide in Australia who was not involved in the study.


Gene drives use a molecular scissors known as CRISPR/Cas9 to insert themselves into a particular site in an organism’s DNA. A gene drive usually contains instructions for making the Cas9 enzyme, which cuts DNA, and a guide RNA that shepherds the enzyme to a particular gene. When Cas9 slices the DNA, cells can repair the break by copying the version of the gene containing the gene drive from its sister chromosome. That copying ensures that all offspring will inherit the gene drive.


Instead, those mice were bred to mice engineered to carry the gene for making Cas9 on another chromosome. In the lab, only mice that inherited both the CopyCat guide RNA and Cas9 together could cut DNA, creating that first generation of genetic cheater mice. Since wild mice don’t naturally make Cas9, the gene drive as it is currently designed wouldn’t be able to spread.



CopyCat also works only in female mice. Bad timing may be the reason the gene drive didn’t go anywhere in male mice, Cooper says. The researchers discovered that the gene drive worked as intended only during a very narrow window of time just before eggs and sperm are made. That window happens during meiosis, when half of an organism’s chromosomes are put into eggs or sperm. Before the chromosomes are divided up, sister chromosomes pair up and exchange information in a process called recombination.


That’s also the perfect time to cut DNA and copy a gene drive, Cooper and colleagues found. CopyCat converted its sister chromosome to carry the gene drive up to 72 percent of the time, which would result in an estimated 86 percent of offspring inheriting the drive, the researchers report. While that’s enough to beat Mendel’s inheritance rules, it falls far short of the 95 percent or better copying rate and nearly 100 percent inheritance seen in some mosquito experiments (SN: 10/27/18, p. 6).


In female mammals, sister chromosomes are paired during recombination for longer than in males, allowing the gene drive more time to work, Cooper says. Cutting when the sister chromosomes aren’t paired resulted in mutations that destroy the Cas9 cutting site, making it off-limits to the enzyme in the future. Even in female mice, cutting created such resistance mutations up to 25 percent of the time.

That rate is “quite high,” says Prowse, and would slow or halt spread of the gene drive in the wild if it were inherited (SN Online: 7/20/17). Cooper and colleagues hope to adjust the timing of when Cas9 makes cuts in male mice so that both sexes can pass along the gene drive.


A rodent gene drive might one day be used to eliminate invasive rodent species that can destroy island habitats and sometimes overrun crops. As is, the gene drive would not work in the wild, says Bruce Conklin, a human geneticist at the University of California, San Francisco, who wrote a commentary in the same issue of Nature. “By no means is this ready to deploy.” But the researchers have taken an important first step in creating a gene drive that could work in mice and possibly other mammals, he says.


Cooper isn’t worried about making a gene drive for use outside of the lab in the near future. Instead, her goal is to create a tool that makes it easier to engineer mice for research, she says. Scientists could insert several human genes into such rodents at the same time, making mice that might better mimic human diseases.  



Cooper and colleagues built half of a gene drive: They inserted instructions for making a guide RNA, but not the Cas9 enzyme, into the gene known as Tyr in mice. The Tyr gene produces the tyrosinase enzyme involved in making pigments. The guide RNA is designed to lead Cas9 to any normal copies of the gene, so that it can be cut and converted to the gene drive version. But this modified gene drive, called “CopyCat,” couldn’t actually cut the mice’s DNA.


source : https://www.sciencenews.org/article/crispr-gene-drive-mice-pest-control-one-step-closer-reality?tgt=nr

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Young emperor penguins brave icy, winter waters in their first year

Only months after their first ocean swim, young emperor penguins are braving Antarctica’s treacherous winter seas. GPS trackers strapped to 15 young penguins showed the birds venturing north to warmer waters beyond Antarctica’s pack ice in December 2013, and returning a few months later as the waters chill.


That finding surprised some scientists, who thought the inexperienced juveniles might play it safe closer to the Antarctic sea ice’s edge rather than risk freezing or drowning in the choppy, ice-strewn open sea. After all, “they just learned how to dive a few months beforehand,” says marine ecologist Sara Labrousse at the Woods Hole Oceanographic Institute in Massachusetts.

But within a few weeks of being on their own, at around 5 months old, these plucky penguins were already diving to depths of around 100 meters, like adults do, the researchers report January 17 in Marine Ecology Progress Series. That’s just after they shed their fluffy down, and before they’ve built up an insulating fat layer.

The tracked birds then headed more than 1,000 kilometers north to open, ice-free waters, in some cases reaching points roughly halfway between Antarctica and Australia. Data from more than 62,000 dives indicate the emperor penguins (Aptenodytes forsteri) make mostly shallow dives there, likely hunting fish and krill that feast on floating algae, the authors say.

In March or April, when the birds were about 8–9 months old, the fattened youngsters returned south and ventured back to Antarctica’s sea ice for winter.


Scientists don’t yet know why the penguins return to the ice, Labrousse says, suggesting it could be to feed on krill that eat algae attached to bottom of ice. Learning more about these early behaviors helps scientists understand how lost sea ice and other changes could affect the penguins — a task that’s becoming more important amid climate change.


source : https://www.sciencenews.org/article/young-emperor-penguins-brave-icy-winter-waters-their-first-year?tgt=nr

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Prosecco production takes a toll on northeast Italy’s environment

Sorry to burst your bubbly, prosecco lovers, but skyrocketing demand for the sparkling wine might be sapping northeastern Italy’s vineyards of precious soil — 400 million kilograms of it per year, researchers report in a study posted online January 10 at bioRxiv.org


That’s a lot of soil, but not an anomaly. Some newer vineyards in Germany, for example, have higher rates of soil loss, says Jesús Rodrigo Comino, a geographer at the Institute of Geomorphology and Soils in Málaga, Spain, who was not involved in the study. And soil erosion isn’t necessarily a bad thing; it can help generate new soils to keep an ecosystem healthy.


But the amount of erosion from Italy’s high-quality prosecco vineyards is not sustainable, he says. Letting too much earth wash away with rain and irrigation could jeopardize the future of the region’s vineyards, which produce 90 million bottles of high-quality prosecco every year.

 
Concerned that the recent bottle boom was taxing the local environment, a team led by researchers from the University of Padua in Italy calculated the “soil footprint” for high-quality prosecco. It found the industry was responsible for 74 percent of the region’s total soil erosion, by studying 10 years-worth of data for rainfall, land use and soil characteristics, as well as high-resolution topographic maps.


The team then compared their soil erosion results with average annual prosecco sales to estimate the annual soil footprint per bottle: about 4.4 kilograms, roughly the mass of two Chihuahuas.
Prosecco vineyards could reduce their soil loss, the scientists say. One solution — leaving grass between vineyard rows — would cut total erosion in half, simulations show. Other strategies could include planting hedges around vineyards or vegetation by rivers and streams to prevent soil from washing away.


Comino agrees, saying: “Only the application of nature-based solutions will be able to reduce or solve the problem.”


source : https://www.sciencenews.org/article/prosecco-production-toll-northeast-italy-soil-environment?tgt=nr

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Cryptic remains of tiny animals have turned up in an Antarctic lake

Much to their surprise, scientists in Antarctica have uncovered what appear to be remnants of tiny animals in mud dredged from a lake that has been covered by a thick mantle of ice for thousands of years.


The researchers on this expedition — known as the Subglacial Antarctic Lakes Scientific Access, or SALSA  — are the first to sample Lake Mercer, a body of water about 600 kilometers from the South Pole. After drilling about a kilometer through the ice in late December, researchers lowered instruments that brought water and sediment up to the surface.


Looking at these samples under a microscope, the team found “some things that looked like squished spiders and crustacean-type things with legs … some other things that looked like they could be worms,” says expedition member David Harwood, a micropaleontologist at the University of Nebraska–Lincoln. The researchers also spotted what appeared to be the vestige of a famously durable microscopic critter called a water bear (SN Online: 7/14/17). Examining the DNA of these remnants will help researchers ID them more precisely.


This find, first reported online by Nature on January 18, “is really intriguing,” says Slawek Tulaczyk, a glaciologist at the University of California, Santa Cruz who is not part of the SALSA team. Until now, scientists hadn’t considered such Antarctic lakes like Mercer to be suitable environments for organisms larger than microbes.


When researchers in 2013 sampled Lake Whillans, the only other ice-lidded lake in Antarctica that scientists have drilled into, “we didn’t uncover any evidence of anything more complex than a microbe,” says SALSA team member Brent Christner, a microbiologist at the University of Florida in Gainesville (SN: 9/20/14, p. 10). “We had a similar expectation here.”


source : https://www.sciencenews.org/article/cryptic-remains-tiny-animals-antarctic-lake-mercer?tgt=nr

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Our fascination with robots goes all the way back to antiquity

Artificial intelligence and robotics are hot scientific fields today. But even in the brave new world of AI, there’s nothing new under the sun, writes classics and science history scholar Adrienne Mayor in Gods and Robots.

In a breezy and thought-provoking account, Mayor describes how ancient Greek, Roman, Indian and Chinese myths expressed hopes and fears about human-made life long before conversational robots and computer chess champions flexed their algorithms. Mayor argues that myths influenced, and were influenced by, real animated machines invented by ancient engineers.


Many Greek myths focused on what Mayor calls biotechne, or “life through craft.” Consider Talos, a giant bronze robot in the epic third century B.C. poem “Argonautica,” which tells the story of Jason and the Argonauts. Hephaestus, blacksmith for the gods, created the automaton Talos to guard a kingdom on the island of Crete. When Jason’s crew arrives, Talos breaks rocks off a cliff and heaves them at the sailors. When the sorceress Medea fixes a disorienting glare on Talos, the giant stumbles, cuts his ankle on a rock and, in a sense, bleeds out. A single internal vein carried Talos’ life force, a substance called ichor that in Greek myths granted immortality to the gods.


Talos’ tale demonstrates how the Greeks used biological knowledge to inform myths of manufactured beings and to ponder a future in which technology could produce artificial life. Talos’ anatomical weak point was chosen for a biological reason, Mayor argues. Ancient medical texts on bloodletting procedures describe a thick ankle vein as best suited for draining blood from patients. In early versions of the myth, a nail in Talos’ ankle sealed in the fluid that animated his body.


Other parts of the book recount how Greek myths imagined robotic servants and a beautiful but deceitful artificial maiden programmed to unleash disasters on humankind. Her name was Pandora. She offered a warning about the dangers of life that’s “made, not born,” Mayor writes.


Mayor also explores accounts of actual self-moving machines. Egyptians, for instance, created a seated female statue that stood up, tilted over to pour milk from a vessel and sat down. Gears, weights and other parts may have moved the nearly 4-meter-tall figure, known only from a description.


As Mayor explains, ancient civilizations told tales of a conflicted desire to transcend death and create artificial life. Those same longings inspire some of today’s humanoid bots and brain-computer interfaces. But, she cautions, modern algorithmic entities have weak points, just as Talos did.



dikutip dari laman : https://www.sciencenews.org/article/our-fascination-robots-goes-all-way-back-antiquity?tgt=nr

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The moon’s craters suggest Earth hasn’t erased lots of past impacts

A new look at the moon’s craters suggests the Earth and moon both suffered a sharp increase in impacts around 290 million years ago, and Earth has kept its biggest scars.

Geologists long assumed that erosion and tectonic activity had erased Earth’s craters so thoroughly that “you couldn’t say anything about the craters on Earth at all,” says planetary scientist Rebecca Ghent (SN: 12/22/18, p. 40). So to figure out how much Earth was pummeled in the past, Ghent and her colleagues turned to the moon.

“We can use our closest neighbor to learn a lot more about the Earth’s history,” says planetary scientist Sara Mazrouei, who worked on the study as a graduate student under Ghent at the University of Toronto.

With no atmosphere and no plate tectonics, the moon’s surface preserves a record of nearly all of its 4.5 billion years of craters. If the moon sat through a hailstorm of impacts, Earth should have experienced the same storm, and therefore the same rate of cratering, the researchers argue in the Jan. 18 Science. But without knowing how old most lunar craters are, it’s unclear if the Earth and the moon suffered impacts constantly or in short bursts.

Ghent realized in 2014 that the youngest craters on the moon were surrounded by large rocks, debris excavated by the impact that formed the crater (SN: 4/14/18, p. 32). Those large rocks absorb heat from the sun during the lunar day and radiate it back out at night in wavelengths of light visible to NASA’s Lunar Reconnaissance Orbite.

“Right away you could see the young craters popping out,” Ghent says. Older craters, by contrast, were surrounded by rocks that had been beaten down to dust over time, so they didn’t glow as brightly at night.



Ghent used nine craters whose ages were already known to figure out a mathematical relationship between a crater’s nighttime glow and its age. Then Mazrouei, working by hand, mapped all 111 lunar craters less than a billion years old and wider than 10 kilometers in diameter, and used that map to figure out the cratering rate.

Most lunar scientists assumed that, after an early turbulent period of extreme bombardment more than 3 billion years ago, the moon’s impact rate has been mostly constant. “But we saw an increase,” Mazrouei says — specifically, a jump in impacts by a factor of 2.6 around 290 million years ago.
The team then compared the lunar craters’ sizes and ages with 38 of the largest and most stable craters on the Earth. They lined up almost exactly in their timing and sizes.


To double check that such large craters on Earth weren’t often erased by erosion, the researchers looked at volcanic features called kimberlite pipes near the craters. These carrot-shaped lava tubes change starkly in appearance when eroded. The kimberlite pipes that appeared on the same terrain as the large craters confirmed that very little of either feature had been lost to erosion, Ghent says.


The jump in the impact rate could have been caused by a smash-up in the asteroid belt sending debris toward the inner solar system, says coauthor William Bottke, a planetary scientist at the Southwest Research Institute in Boulder, Colo. In 2007, Bottke linked one such asteroid break-up to the impact that killed the dinosaurs (SN: 9/8/07, p. 148).


Ghent cautions against drawing conclusions about an exact date for that spike in impacts, noting it could have happened tens of millions of years earlier or later than estimated, or in multiple spurts. “I don’t want people to say, ‘Hey, the Permian-Triassic extinction happened during that time. This might have caused it.’ We don’t know that,” she says.


The new finding offers an explanation for a gap in Earth’s craters between 300 million and 650 million years old, Bottke says. “We don’t see fewer craters because of erosion,” he says. “We see fewer craters because the impact flux was lower.”


But the craters’ longevity raised another question. While the moon’s craters date back billions of years, Earth has almost no preserved craters older than about 650 million years. That makes sense if craters are lost constantly to erosion. But if not, where did the older craters go?

Older craters could have been scraped away during a global glacial period called Snowball Earth, Bottke says. Other lines of geological evidence suggest Earth went through deep freezes, the last of which occurred about 650 million years ago.Other planetary scientists not involved in the study expressed mixed reactions about its methodology and findings.

“That is a major step forward in our understanding of the impact flux in the inner solar system,” says planetary scientist Christian Koeberl of the University of Vienna. “Their method is interesting and new.”


Geologists Thomas Kenkmann and Stefan Hergarten of the University of Freiburg in Germany are more skeptical. In 2015, the duo showed that many of Earth’s craters could still be undiscovered (SN: 7/25/15, p. 5). They’re not convinced that the new study captured all craters, or that Earth’s crater count reflects an increase in impact rate 290 million years ago. It could just be that “younger craters are more likely to have survived,” Hergarten says. “The dataset is really small, so I would not trust in it too much.”


Kenkmann agrees. “Considering the low number of craters for the lunar calculation, and the vague interpretation of the terrestrial record, it appears that a house of cards is being built here.”


source : https://www.sciencenews.org/article/moon-craters-suggest-earth-preserves-past-asteroid-impacts?tgt=nr

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