Tag Archives: mouse

Rare and elusive semi-aquatic mice discovered in Africa

An illustration of one of the newly-described species of stilt mouse, Colomys lumumbai, wading in a stream to hunt. Credit: Velizar Simeonovski, Field Museum.

Almost a century ago, biologists described an odd new mouse genus, called Nilopegamys, that lived in Ethiopian streams based on a single collected specimen. By the looks of it, it is one of the most adapted rodents to aquatic living, having a beautiful water-resistant fur and relatively long, broad feet. No other specimen had been sighted since then, and scientists now fear it is extinct.

But, in a new study, an international group of scientists led by biologists at Chicago’s Field Museum of Natural History claim they’ve identified two new species belonging to a related genus of African semi-aquatic mice, known as Colomys.

“We embarked on this study to understand the evolutionary relationships among the two genera of African semi-aquatic mice. These include: the genus Nilopegamys, which is known by a single specimen collected almost 100 years ago in Ethiopia and the much more widespread genus Colomys, mostly distributed within the Congo basin but with populations in east and west Africa. We also aimed to determine if there was any undescribed diversity within the genus Colomys (i.e., new species),” Julian Kerbis Peterhans, Adjunct Curator at the Negaunee Integrative Research Center at the Field Museum, told ZME Science.

Swimming rodents in one of the world’s richest biodiversity hotspots

For the last three decades, Peterhans has been doing challenging fieldwork in the Congo Basin, an amazingly rich biodiversity hotspot, setting up traps and studying various rodents. In their new study, Peterhans and colleagues at The Field Museum, the University of California San Diego, DR Congo, and Kenya, focused on Nilopegamys and Colomys.

Nilopegamys, which means ‘mouse from the source of the Nile’, has been described from a single specimen in 1927, which is housed at the Field Museum. Colomys is active in the wild, but still highly elusive due to its habitat. These cute mice use their kangaroo-like elongated feet to wade through shallow streams on the prowl for water-dwelling insects like caddisfly larvae.

“After I caught my first semi-aquatic mouse over 30 years ago I was hooked. I have most often caught them at the edge of pristine shallow streams or on rocky or sandy outcrops within, often with light only trickling through. When I caught my first one I thought it to be the most beautiful mouse I had ever seen with a striking contrast between a white belly and black or grey back. Feet exceptionally elongate. Fur velvety, soft, and water-resistant,” Peterhans told me in an email.

“The genus Colomys is quite rare in collections because their density is low compared to more traditionally terrestrial mice. Collectors do not realize traps need to be placed within or on the edge of streams. But assuming their streams remain unpolluted and forest remains intact, they will not be threatened. However, mining for gold and coltan and general forest degradation are their major threats.”

“Sadly, the genus Nilopegamys may be extinct as their habitat near Lake Tana in Ethiopia is completely degraded. The only chance for their existence is to survey any intact habitats along the Blue Nile in Ethiopia as it descends to meet the White Nile in Sudan,” he added.

Stalking mice in the bush

In order to catch Colomy mice, the researchers had to maneuver through rough and swampy terrain, often traveling through water up to the waist. “And you can have torrential rain in the tropics, so sometimes half the traps get swept away, and you have to go downriver to try to find them,”  Terry Demos, a postdoctoral researcher at the Field Museum and another of the paper’s authors, said in a press release. But the wet terrain was often the least of their worries.

“Memorable moments can be horrific, delightful and are limitless: medical evacuation due to depleted oxygen (histoplasmosis), local militias kidnapping and killing Congolese colleagues, 3-4 day hikes through the bush in order to find suitable habitat to collect specimens, delight in working with host-country colleagues, a hot cup of coffee at 7 am after checking traplines, crossing the Semliki River with a single outboard motor strapped to the canoes and wooden planks supporting two vehicles, the first time terror of hearing the screeching tree hyrax at nightfall,” said Peterhans.

Using specimens they collected during fieldwork in the Congo and those already in museum collections, the researchers compared the rodents’ physical traits and sequenced their DNA.

These analyses revealed two new species that hadn’t been described before: Colomys lumumbai and C. wologizi, after Congolese independence leader Patrice Lumumba and Liberia’s Wologizi Mountains, respectively. What’s more, genetic data enabled the researchers to promote the subspecies Colomys gosling eisentrauti from the Bamenda Highlands of Cameroon to full species status (Colomys eisentrauti).

“One new species we described (Colomys lumumbai) is nearly indistinguishable from its closest relative (Colomys goslingi) and only through the genetic work and careful morphological analyses of skull measurements were we able to tease this species apart,” Peterhans said.

That’s not all. One of the team’s members, Tom Giarla, who is an assistant professor of biology at Siena College in New York, also endeavored to sequence the DNA from the dried tissue of the skull of the 93-year-old Nilopegamys specimen. Preparing and sequencing DNA this old is no trivial task, but Giarla’s expertise shined.  “I was stunned that I actually got it to work on my first try,” Giarla proudly stated, whose genetic wizardry showed that Nilopegamys is a sister genus to Colomys. In other words, the two genera are very closely related.

Learning such new things about mice living in streams in the African rainforests is just the tip of the iceberg. These areas are home to a wide range of animal species, many of them new to science. But due to the rugged habitat, poor infrastructure, and political instability, scientists face many challenges.

In the age of the COVID-19 pandemic, such efforts should be supported more. The coronavirus is zoonotic, meaning it first evolved in an animal species before jumping to humans. Such is the case for Ebola and HIV, too.

“The rainforests of the Congo Basin and surrounding highlands are incredible hotspots of tropical diversity but are also under great threat of habitat destruction. We strongly suspect many new species are awaiting discovery, including the relatively well known small mammals. Based on our work to date dozens of new species of rodents await discovery along with many species of bats, shrews and other small mammals. These findings are critical for informed conservation of the Congo rainforests,” said Peterhans.

“In this day of climate change, the spread of zoonotic disease and global mass extinction, studies such as ours are at a premium. Global biodiversity must be documented. Every species has a unique genetic toolkit in fighting disease, and interacting with the environment and competitors. Every species is also a canary in the coal-mine speaking to the vulnerability of local climates and habitats. There remains much more to explore in Africa where species numbers are greatly increasing despite severe habitat degradation. This year’s expeditions to Africa have been sadly postponed due to COVID; every year counts,” he concluded.

Artist impression of the field mouse (left) and a spectral analysis of the fossil's fur, showing it was colored red. Credit: Nature Communications.

Scientists find red coloring for the first time in a 3-million-year-old ‘mighty mouse’ fossil

Using advanced X-ray technology, an interdisciplinary team of researchers has, for the first time, identified red pigments in an ancient fossil. It belonged to a now-extinct 3-million-year-old mouse, called Apodemus atavus and nicknamed “mighty mouse”, which was found near the German village of Willershausen.

Artist impression of the field mouse (left) and a spectral analysis of the fossil's fur, showing it was colored red. Credit: Nature Communications.

Artist impression of the field mouse (left) and a spectral analysis of the fossil’s fur, showing it was colored red. Credit: Nature Communications.

Researchers at the University of Manchester in the UK were amazed by how well preserved the fossil was, with most of the skeleton and soft tissue still present and easily recognizable. But, even under such fortunate conditions, it would have been impossible to resolve the biochemical information of the tissue without the help of high-powered X-ray tools, like the SLAC’s Stanford Synchrotron Radiation Lightsource and the Diamond Light Source in the UK.

“Life on Earth has littered the fossil record with a wealth of information that has only recently been accessible to science,” says Phil Manning, a professor at Manchester who co-led the study. “A suite of new imaging techniques can now be deployed, which permit us to peer deep into the chemical history of a fossil organism and the processes that preserved its tissues. Where once we saw simply minerals, now we gently unpick the ‘biochemical ghosts’ of long extinct species.”

Credit: Nature Communications.

Credit: Nature Communications.

The team of researchers, which included experts in paleontology, geochemistry, and X-ray spectroscopy, were able to detect trace metals in the pigments (melanin), revealing that the rodent’s fur was red. In mammals and other animals, there are two types of melanin, the brownish-black eumelanin, and the reddish pheomelanin. The authors even translated the spectral images into sound waves, showing that different frequencies are associated with different sounds.

“This study demonstrates that the spatial distribution of different forms of melanin residues in extinct organisms may be resolved nondestructively over large areas (dm2) even after 3 million years of degradation,” the researchers wrote.

In the future, the same technique could be used on many other fossils, revealing the stunning coloring of long-gone animals. It was only ten years ago that researchers identified black pigments in an ancient fossil. What’s more, coloring might offer new hints and clues that scientists are now missing when studying the evolution of certain extinct organisms.

“As you do research in a particular area, the scope of your techniques might evolve,” says Uwe Bergmann, co-author and a distinguished staff scientist at SLAC who led the development of the X-ray fluorescence imaging used in this research. “The hope is that you can develop a tool that will become part of the standard arsenal when something new is studied, and I believe the application to fossils is a good example.”

The findings appeared in the journal Nature Communications.

Scientists activate tooth regeneration in mice

Credit: Pixabay.

Humans have two sets of teeth, the second of which is meant to replace our temporary deciduous teeth or “baby teeth.” Other animals, such as reptiles or fish, can regenerate teeth indefinitely during their lifetime. Mice, however, are born with a single set of teeth.

Looking to understand the evolutionary drivers between different tooth replacement strategies, researchers at the King’s College London studied dental development in mice. They identified a molecular signaling pathway in the rodents’ dental lamina, the area that forms the teeth, and using genetic techniques managed to regenerate a new set of teeth.

The researchers, led by Professor Abigail Tucker, first compared gene expression in the dental lamina of the mouse and the minipig, which has two sets of teeth. 

The research team found that Wnt signaling, which is normally required for tooth replacement in other vertebrates, is missing in a rudimentary form of the dental lamina (RSDL) in mice.

Using genetic techniques, the researchers activated this signaling pathway in the mouse RSDL, revitalizing the structure and ultimately leading to the formation of new teeth.

The study shows that RSDL may be a source of replacement teeth in mice and provides an experimental framework for studying the mechanisms behind replacement.

“Why the potential for tooth replacement varies so much across vertebrates is an intriguing question”, explains PhD student Elena Popa. “Our results show that, although the mouse normally does not form a second replacement set of teeth, it still has the potential to do so given the right signals.”

The authors also reported that culturing RSDL in isolation resulted in tooth formation, suggesting that the previous set of teeth also influences the development of the next.

Professor Tucker explains: “This is relevant to human tooth replacement, as structures similar to the RSDL have been identified next to the permanent teeth during development. In normal development of our teeth, therefore, the second set or permanent tooth may inhibit the generation of a third set of teeth.”

The findings appeared in the journal Development

map

Scientists reprogram brain cells that store memories about places

map

Credit: Pixabay.

Without long-term memory, none of us would be functional human beings. In order to make sense of the world, our memory employs all sorts of reference points, anchors if you will. For instance, one very important building block is the memory of places. Scientists think that the memory for a given environment is stored in specific neurons in the hippocampus, which is the memory formation center in the brain. These neurons are called place cells. Now, German researchers have reported an incredible feat — they’ve ‘reprogrammed’ such place cells in free-roaming mice.

Research suggests that memories about particular locations come together in place maps. Each map is stable as long as we are in that particular environment, but it reorganizes its activity patterns with different locations, thus leading to a new place map for each environment.

Dr. Andrea Burgalossi of the University of Tübingen and colleagues investigated the mechanisms that underlie the reorganization of place cell activity. Two years ago, the same team of neuroscientists showed that so-called silent or dormant cells could be reactivated by electrical stimulation, thereby becoming active place cells. The researchers now revisited this work and built upon it, toying with new ways to form place cells. Quite strangely, the new work suggests that place cells aren’t nearly as stable as we used to think — in fact, place cells can be reprogrammed.

The team used a novel method based on juxtacellular recording and stimulation where very fine electrodes as thin as strands of hair measure and induce tiny currents along individual place cells. The researchers performed this procedure on rats freely roaming an arena in the lab. By stimulating individual place cells in the rat’s brain in a different location from where they had originally been active, the activity of the place cells could be reprogrammed. In other words, the cells stopped firing in the original locations and became active in the area where the electrical stimulation occurred.

“We challenged the idea that place cells are stable entities. Even in the same environment, we can reprogram individual neurons by stimulating them at specific places”, says Andrea Burgalossi. “This finding provides insights into the basic mechanisms that lead to the formation of new memories”. I

“So far, we have reprogrammed single neurons, and it would be fascinating to find what influence this has on place maps as a whole. We would very much like to know what is the minimum number of cells we need to reprogram in order to modify an actual memory trace in the brain.”

Scientific reference: Maria Diamantaki, Stefano Coletta, Khaled Nasr, Roxana Zeraati, Sohie Laturnus, Philipp Berens, Patricia Preston-Ferrer, Andrea Burgalossi: Manipulating Hippocampal Cell Activity by Single-Cell Stimulation in Freely-Moving Mice. In: Cell Reports (in press) April 3rd, 2018.

mouse-mind-control

Mind-controlled mice are forced to ignore food, water, and sex to complete maze

mouse-mind-control

Credit: Korea Advanced Institute of Science and Technology.

Scientists hijacked the brains of lab mice by literally shining light into their neurons, making the rodents respond to external commands as if they were remote-controlled. When the mind-control setup was activated, the mice cared very little anymore about what they would normally be their favorite things to do — eat, drink, have sex. Their only preoccupation was to follow the researchers’ commands as they were directed to the end of a maze.

At the crux of this rather disturbing method lies a technique called optogenetics, which involves the use of light to control cells in living tissue, typically neurons, that have been genetically modified to express light-sensitive ion channels. Researchers at the Korea Advanced Institute of Science and Technology surgically implanted a little box on the skulls of engineered mice, which contained LEDs, a battery, and a Bluetooth-tethered microcontroller. A sophisticated machine-learning algorithm interpreted the instructions sent by the researchers into flashes of light which fired on and off at light-responsive proteins, altering their function.

During the experiment, a red ‘crave’ ball was attached by a flexible string right in front of the mouse’s field of vision. Yes, the old carrot-chasing trick. If the setup was deactivated, the mouse wasn’t at all interested in the ball. However, when it was activated, the mouse couldn’t help itself but follow the red ball, which could be steered, along with the rodent, by the researchers as they pleased.

The Korean researchers used this setup to steer the remote-controlled mice through a maze that was packed with obstacles and distractions at every turn. Along the way, the mice were tempted by delicious food, a female in heat or water. They also met obstacles like a narrow bridge over water or confusing road bumps that would have otherwise been intimidating for the mice. Despite these distractions, the researchers were able to steer the mice right to the end of the maze without the rodents ever flinching.

The team thinks that their method could be refined to enable precise control of biological organisms that are far more suitable, perhaps cheaper too, than robots for some select applications. For instance, one can imagine leveraging a mouse’s keen sense of smell for search and rescue missions or landmine detection.

This isn’t the first time scientists have taken control of animals. Other examples include worms, a cyber-cockroach, and a turtle. And I know what you’re thinking right now: If this can be done on mice, could the same technology be used on humans? That’s an interesting prospect to entertain, and it certainly doesn’t seem impossible in light of recent development.

The findings appeared in the journal Nature Neuroscience

Mouse space sperm could pave a new era of space exploration

How one of the big questions about a potential space age was answered.

These baby mice were born from sperm flown aboard the International Space Station for about nine months. Image credits: Teruhiko Wakayama.

If we want to discuss long-term space travel or some sort of colonization, there’s one thing which always comes up: reproduction. We’re good at that on Earth (perhaps even too good, I’d say), but can we do it in outer space or on Mars? This isn’t just some random question, we genuinely don’t have a good idea how reproduction is affected by low-gravity and increased radiation. Well, according to a study published this week in Proceedings of the National Academy of Sciences, we shouldn’t worry too much about that: researchers used freeze-dried sperm stored on the International Space Station (for nine months), and it produced healthy offspring. While this doesn’t necessarily mean the same applies to humans, it’s quite promising.

Kris Lehnhardt, a physician at George Washington University who specializes in emergency and extreme-environment medicine comments on how much we don’t know about these aspects:

“We really don’t know any of the things that we need to know to say that human reproduction in space is going to be successful or safe,” he says. “It’s not been studied in much detail.”

No one has really had sex in outer space (not officially, at least), so we don’t really know how that works. With all this in mind, developmental biologist Teruhiko Wakayama wanted to answer some of the questions regarding the safety of reproduction in outer space.

“We found that only a few studies were performed about mammalian reproduction in space, and most of them showed no clear results due to the difficulty of taking the mice or rat into space,” says Wakayama, of Japan’s University of Yamanashi.

So he kicked up project “Space Pup,” which had the official goal of studying the difficulties of mammalian reproduction in outer space — focusing on mice. After extracting sperm from mice, he handed it to astronauts who stored it on the ISS from August 2013 to May 2014, after which it was brought back to Earth, fertilized in vitro and used on female mice. The females produced healthy offspring, who in turn produced healthy offspring — showing no sign of health or genetic problems.
What’s really interesting is that this happened although the sperm itself did show some evidence of DNA damage. This indicates some intriguing resilience, but it’s also worrying: If we are to travel to Mars or beyond, there would be even more radiation, doing likely even more damage.

“The radiation exposures that are reported in the paper are nowhere near the level of the radiation exposures that are going to be experienced once we travel beyond the protection of the Van Allen belt,” Joe Tash of the University of Kansas Medical Center told National Geographic, referring to another layer of radiation shielding that’s wrapped around Earth and that envelops the ISS.

The findings aren’t necessarily surprising. Astronauts go on the ISS all the time, and they can still have babies. Even those who spend lengthy periods there and even go out for spacewalks and are exposed to extra radiation do quite fine. Still, sperm is one of the most vulnerable cells, and if something were to go wrong (such as too much exposure to radiation), that’s pretty much the first place you’d look for damage. However, this still doesn’t tell us anything about how microgravity and increased radiation affect conception (done the old fashioned way), pregnancy, fetal development, or even giving birth. Could we safely have space babies? That’s an open question.

Now, Wakayama wants to try the other thing: send some fertilized mouse eggs to the ISS and see how they fare, as well as try similar things with cryo-preserved human sperm (not fertilize someone, just take it to outer space, bring it back, and study it).

Journal Reference: Sayaka Wakayama et al — Healthy offspring from freeze-dried mouse spermatozoa held on the International Space Station for 9 months. doi: 10.1073/pnas.1701425114

mouse brain

Big-brained mice engineered using human DNA

In the quest to understand what are the crucial differences between human and chimpanzee brains, scientists have isolated a stretch of DNA, once thought to be “junk”, near a gene that regulates brain development in mice. The engineered mouse embryos grew significantly larger brains. Those which received human brain DNA strands had 12% larger brains than those bred with chimp brain DNA. Research like this, though ethically controversial, might help identify which DNA sequences give a brain human characteristics, but also aid in findings treatment or cures for brain diseases like Alzheimer’s.

mouse brain

Image: Current Biology

It’s a common fact thrown about that humans and chimps, often called our cousins, share 95% of their DNA. Though it’s easy to see a piece of you in the eyes of a chimp, we humans and chimps are quite different. Basically, we’re more complex,  something that can be easily interpreted from brain size. Depending on the specimen, chimp brains are two to four times as small as the human kind. Debra Silver, a neurobiologist at Duke University Medical School, is studying DNA code that is different between the two or unique to each species in an attempt to piece those pieces of DNA that made humans the dominant species on Earth. For, make no mistakes, we owe it all to our superior intellect.

“We went through those and picked out ones that seemed to be likely to be regulating gene activity in a developing brain,” explains Silver.

The researchers focused on a particular DNA stretch which looked promising since it was located near a gene known to be involved in brain development. So, to see what could happen, the researchers added the chimp version of the DNA to mouse embryos. Then, in other mouse embryos, they added the human DNA.

“What we discovered is that the human DNA turned on gene activity in neural stem cells, and these are cells which produce the neurons of our cerebral cortex,” says Silver.

current biology -

Image: Current Biology

All the mice grew bigger brains than they would have normally, but those embryos infused with the human DNA had a significantly bigger brain than the rest – 12% larger than those bred using the chimp variety of the DNA, according to the paper published in Current Biology. What’s interesting is that this particular DNA code was thought to be “junk”, a slag for DNA that doesn’t code proteins. Evidently, discoveries like these overthrow this common assumption that see “useless” DNA as serving no purpose. The genome – the entire DNA sequence of an organism – is made up of a small number of genes. The rest or bulk of it is comprised of DNA that regular gene expression. Code that turns a gene on or off, and more often than not it’s gene expression that make all the difference between a human, chimp or mouse, and not the presence of a gene itself.

“We have very little scientific information about the actual functions of those regions,” says Katie Pollard, who studies human and chimp DNA at the Gladstone Institutes and the University of California, San Francisco.

Most of the genetic differences between humans and chimps are actually found in the so-called junk DNA, Pollard notes. “While it’s now pretty easy to find the genetic differences, it’s very challenging to figure out exactly whether those differences made a change in a trait, and why.”

This new study, says Pollard, “is helping to try to bridge that gap.”

But will the big-brained mice be smarter? It’s very difficult to gauge this kind of cognitive enhancement, but the researchers are most excited about probing this idea once the pups reach adulthood. Ideally, the best results would be seen if scientists would tinker with switching off and on genes in human and chimpanzee embryos, but this would be dubiously unethical. Instead, Pollard and colleagues are keeping their eyes on petri dishes.

“We can now actually generate the equivalent of embryonic brain cells and tissues that are human or chimpanzee,” says Pollard. “And, using genome engineering techniques, we can start to study the effects of switching the human and the chimp sequences in these primate cell lines.”

Could this sort of research render super animals with human-like cognition? Well, according to those involved something out of Planet of the Apes is why too far ahead, if not impossible. But while we won’t make mice that can speak any time soon, this sort of tinkering with the brains of nonhuman primates or other reasonably intelligent animals, like pigs, is seemingly unethical and merits particular attention.

“The prospect of, sort of, tearing down the barriers between humans and other nonhuman species in ways that really threaten our sense of ourselves as special is disturbing,” Ruth Faden points out, who directs the Johns Hopkins Berman Institute of Bioethics.

sugar water

Reactivating positive memories might fight depression [TED Talk]

Steve Ramirez and Xu Liu are two neuroscientists who are at the very forefront of their field. Their work is focused on mapping the memory system, but also on how memory activation alters neural pathways, thus changing our mood. For instance, the two spoke recently during a TED talk about their most impressive experiment yet where they used blue light to activate a fond memory in depressed mice. The mice were visibly in a better mood, suggesting that depression – a far more complex and difficult to treat mental disorder than most ‘healthy’ people think – can be dispelled using a similar method on humans, as well. Moreover, the changes caused an increase in the number of neurons, enforcing the idea that this kind of treatment actually gives results.

Switching depression off

Steve Ramirez and Xu Liu spend their days in a lab at MIT, working to manipulate the memories of mice. Image: TED

Steve Ramirez and Xu Liu spend their days in a lab at MIT, working to manipulate the memories of mice. Image: TED

I first heard about the MIT researchers when I wrote a piece about a breakthrough in neuroscience, describing how they found memories are stored in specific brain cells. A most impressive feat, but now it’s been taken to a whole new level. The team engineered a harmless virus that activates brain cells in mice when exposed to pulses of light. The virus acts as “a sort of light-sensitive switch that can be artificially installed in brain cells,” Ramirez says , “to activate or inactivate the brain cell simply by clicking it, and in this case we click it on with pulses of light.”

Last year, they demonstrated how pulses of light were used to trigger the memory of fear in a mouse not immediately facing any dangerous or fear-inducing situations, a memory that caused an otherwise calm and curious mouse to freeze in its tracks. This technique falls under an innovative field called optogenetics. Later, Ramirez and Liu attempted to induce positive memories and emotions.

The story of a depressed mouse

sugar water

Credit: TED

To detect those mice that were depressed, the team gave mice an option between sugar water and regular water. Those that were healthy showed a strong preference for the sweet water 80& of the time – a real treat! Some mice, however, chose the sugar water only 50% of the time. This probability equal to that of flipping a coin tells us that the mice couldn’t care less where they got their water as long as it quenched their thirst. This is a classic depression symptom: nothing seems to bring pleasure or attract you any way anymore.

But to use the same technique as previously demonstrated when fear was induced, the researchers had to know what memories a mice cherishes. It’s not like you can ask a mouse what’s their favorite, most fond memories though. Eventually, they locked in: male mice were happiest when they were put in a cage with a female. They activated this memory in mice with depression-like symptoms then offered them again the choice between sugared and normal water. Amazingly, the depressed mice chose the sugary water 80% of the time suggesting a complete success!

It’s been proven that depression inflicts physical changes to the brain. A depressed individual, human or otherwise, will have fewer neurons on a daily basis, whereas a normal, healthy individual will generate new neurons everyday. Obviously, this is a big problem. At the same time, this knowledge proved to be very useful since it acted as a proxy to see whether Ramirez and Liu actually changed something in the brain, on a physical level. Tests showed that not only did the depressed mice’s behavior changed, they also saw increased number of neurons. Double confirmation, checked.  When this happened, Ramirez recounts in the TED talk (which you should see, by the way!) likened the moment to a “double thick Oreo milkshake multiplied by world peace,”

 

 

Image: Flickr // angeladellatorre]

Mice with half human brains are smarter, some healthier

Oh, boy. This week’s freaky science story comes from the University of Rochester Medical Center in New York where researchers grafted mouse pups with human glial cells. Within one year, half the brain cells of the by now adult mice were human. A study made last year by the same team suggests that mice whose brains contain human glial cells are smarter, while another experiment seems to indicate that mice with defects like uninsulated nerves can repair these nerves if human brain cells are inserted.

The overlooked glia

supermice

Image: Scientific American

It’s important to set one thing straight: the mice still kept their 100% originally sourced neurons. It’s the glial cells that were human. Although there are about 100 billion neurons in the brain – the human one –  there may be about 10 to 50 times that many glial cells. So, why haven’t you heard about them before if they’re so important? You know how fads come and go…

Sure, neurons are the rock stars because they have firing ability and are responsible for all the signaling that goes inside the brain. Without glial cells, however, neurons would never be able to function. There are five types of glia:

  • Astrocyte (Astroglia): Star-shaped cells that provide physical and nutritional support for neurons: 1) clean up brain “debris”; 2) transport nutrients to neurons; 3) hold neurons in place; 4) digest parts of dead neurons; 5) regulate content of extracellular space
  • Microglia: Like astrocytes, microglia digest parts of dead neurons.
  • Oligodendroglia: Provide the insulation (myelin) to neurons in the central nervous system.
  • Satellite Cells: Physical support to neurons in the peripheral nervous system.
  • Schwann Cells: Provide the insulation (myelin) to neurons in the peripheral nervous system.

Steve Goldman of the University of Rochester Medical Center in New York extracted infant glia from donated human embryos and injected these into the brains of mouse pups. Soon enough, the glia started developing into astrocytes, which strengthen the connection between neuron connections called synapses. Human astrocytes are 10 to 20 times the size of mouse astrocytes and carry 100 times as many tendrils.

Taking over

Image: Wikimedia Commons

Image: Wikimedia Commons

Initially, some 300,000 human glia were inserted, but by the end of the year, the mouse had 12 million. This means that nearly all of the mouse’s native glia had been displaced.

“We could see the human cells taking over the whole space,” says Goldman. “It seemed like the mouse counterparts were fleeing to the margins.”

But do the human astrocytes in the mice actually behave as in the human brain or does the environment regulate them?

“That the cells work at all in a different species is amazing, and poses the question of which properties are being driven by the cell itself and which by the new environment,” says Wolfgang Enard of Ludwig-Maximilians University Munich in Germany, who has shown that mice are better at learning if they have the human Foxp2 gene, which has been linked with human language development.

This question will definitely be very interesting to answer. In a parallel experiment, Goldman and team inserted human glia once more into the brains of mice pups, only this time these bore a defect. The mice were poor at making myelin, the protein that insulates nerves.  Once again, the immature glia developed quickly, but this time something amazing happened:  many of the human glial cells matured into oligodendrocytes, brain cells that specialise in making the insulating material. Somehow, the glia recognized the defect and compensated.

[RELATED] Scientists engineer ‘super’ mice 

Multiple sclerosis is a terrible disease in which the myelin sheath is damaged, and the findings suggest that glia therapy might render positive results. In fact, Goldman applied for permission to treat MS patients with the glial progenitor cells, and hopes to start a trial in 12 to 15 months.

Is this still a mouse?

Image: Flickr // angeladellatorre]

Image: Flickr // angeladellatorre]

The same team made a similar experiment last year, only the human glia they inserted were mature. These became integrated into the mouse brain, but didn’t develop further or expanded in numbers. But here’s the interesting part. In a standardized memory test, mice remembered a sound associated with a mild electric shock  for four times as long as other mice when they heard the sound, suggesting their memory was about four times better.

“These were whopping effects,” says Goldman. “We can say they were statistically and significantly smarter than control mice.”

Next, to further determine how human astrocytes affect things like intelligence, memory or learning, Goldman will be grafting the same immature human glia into rat brains. Rats are smarter than mice, so it should be interesting to follow how the humanized rats respond.

Is this a super mouse? Is it a mouse anymore? Is it just a super smart mouse? Well, let’s leave it to Goldman:

“This does not provide the animals with additional capabilities that could in any way be ascribed or perceived as specifically human,” he says. “Rather, the human cells are simply improving the efficiency of the mouse’s own neural networks. It’s still a mouse.

Findings appeared in the Journal of Neuroscience.

Photo: California Academy of Sciences

This sweet shrew looks like a mouse but is more related to elephants

Photo: California Academy of Sciences

Photo: California Academy of Sciences

A new mammalian species has been discovered among the ancient volcanic formation in Namibia that resembles a long-nosed mouse, but which as it turns out is more genetically related to elephants. Further analysis found that the tiny mouse-like creature is the smallest of a group of animals called elephant shrews.

Named Macroscelides micus, the creature sports red fur to help it blend in with the color of its rocky surroundings, measures 7.5 inches (19 cm) in length (tail included) and only weighs roughly an ounce (28 grams). It’s tiny ball of fury delight, made even more adorable by the fact it’s most closely related to an elephant according to genetic analysis. The only visible link between the two, however, is the shrew’s trunk-like nose.

The newfound elephant shrew, Macroscelides micus. Dumbacher et al / Journal of Mammology

The newfound elephant shrew, Macroscelides micus. Dumbacher et al / Journal of Mammology

It doesn’t end here, though. The elephant shrew is related to other animals as well, this time in behavior and physique. The newly discovered animal can be likened to an antelope because of its spindly legs relative to its body size, and because it hunkers down next to bushes to sleep rather than burrowing. Also, concerning its hunting patterns, the elephant shrew behaves like an anteater using its extended nose to sweep the ground in search of ants and other insects.

The creature was described in a paper published in the Journal of Mammalogy.

Bacteria can make you happier AND smarter

Mycobacterium vaccae is a type of bacteria that naturally leaves in soil and has been in the attention of researchers for a while now, due to the fact that it decreases anxiety. Recent studies sugest that in fact, it also stimulates neuron growth and thus intelligence and the ability to learn.

smart-mouseDorothy Matthews and Susan Jenks from The Sage Colleges in Troy, New York believed this bacteria could have a beneficial impact on neurons too, and injected the bacteria in mice which, at first, led to a significantly increased serotonin production. However, researchers were interested in a more indirect effect.

“Since serotonin plays a role in learning we wondered if live M. vaccae could improve learning in mice.”

In order to assess this assumption, they took two groups and injected only one of them with the bacteria, and then tested them in a maze. The difference was easy to notice.

“We found that mice that were fed live M. vaccae navigated the maze twice as fast and with less demonstrated anxiety behaviors as control mice.”

The mice were then tested after the bacteria was removed from their organisms. When they were tested immediatly afterward, they still did better than their counterparts, but not as good as the first time. Three weeks later, they were tested again. The results were still slightly better, but not statistically relevant. This seems to suggest that the boost to learning is of temporary nature, but applied to humans with a greater cognitive capacity, the results might be more spectacular.

“This research suggests that M. vaccae may play a role in anxiety and learning in mammals. It is interesting to speculate that creating learning environments in schools that include time in the outdoors where M. vaccae is present may decrease anxiety and improve the ability to learn new tasks.”