Tag Archives: rat

Rat infestation in Washington DC has produced two cases of rare virus infection

Washington, DC, has a rat problem. According to the Centers for Disease Control and Prevention (CDC), this has led to the emergence of the first two official cases of hantavirus in humans in the city.

Image credits Wolfgang Vogt.

Wildlife has its own share of viruses and pathogens to deal with, as do people. Sometimes, however, when these two groups live in close proximity, pathogens can evolve to cross from one to the other. When this takes place from wildlife or livestock to humans, this is known as zoonosis. The coronavirus pandemic started as a zoonosis.

One genus of viruses that can comfortably infect both rodents and humans is known as orthohantavirus, or simply hantaviruses. These are widespread through rodent populations such as city rats, where they cause asymptomatic infections. However, people can become infected with these viruses as well, most commonly through exposure to rat urine or feces, although saliva or bites can also transmit the virus.

Washington DC’s rat problem has led to the emergence of two known cases of hantavirus infection, the CDC reported Thursday. Transmission from one infected person to another is almost unheard-of with hantaviruses, so concerns about brewing epidemics are far from the CDC’s mind. The infections were recorded in 2018 and have been successfully treated.

Still, the situation poses a risk for the health of people in Washington DC, who should take steps to protect themselves from the rodents.

Vermin threat

“Although extremely rare, the two SEOV cases presented in this report highlight the importance of physicians including hantavirus infection in their differential diagnoses in patients with compatible symptoms and history of animal exposure or travel and underscore the importance of reporting notifiable infectious disease cases to health departments for investigation and response,” the CDC’s report explains. “These cases also serve as a reminder to the public to minimize risk for infection by following recommended hygiene practices.”

Hantavirus infection in people can lead to a host of respiratory and hemorrhagic diseases which can easily become fatal. Fortunately for the cases recorded in DC, the strain identified in the two infected individuals is a milder “Old World” strain called the Seoul virus. Old World hantaviruses cause a disease called hemorrhagic fever with renal syndrome (HFRS). In contrast, “New World” hantaviruses, which are present in the Americas, cause a much more severe respiratory infection known as hantavirus pulmonary syndrome (HPS)– which is much deadlier.

HFRS starts out as a generic infection with fever, chills, nausea, and headache, but can then progress to low blood pressure, acute shock, vascular leakage, and acute kidney failure, the CDC notes. The severity of HFRS varies by the strain of hantavirus that causes it, and can reach up to 15% fatality. In the case of the Seoul virus, fatality rates are around 1%. Both individuals reported-on by the CDC made a full recovery.

HPS also begins as a generic infection with fever, chills, and aches, but quickly progresses to an acute, life-threatening phase after about a week. The patient’s lungs and heart are affected; the lungs fill with fluid, and patients require hospitalization and ventilation within 24 hours. HPS is fatal in about 38% of cases, according to the CDC. The deadliest such virus, the Sin Nombre virus, spread by the deer mouse, has a fatality rate of about 50%.

HPS and the Sin Nombre virus first came in the crosshairs of US health officials following an outbreak of deadly respiratory disease in the Four Corners region. In total, 48 cases were identified in that year, 27 of which were fatal. The CDC finally tracked the virus down to rodents in the area, and it gained the moniker of Sin Nombre virus (the virus with no name) during this process.

The Seoul virus has a much lower prevalence in the US, and spreads from the common brown rat, which travelled to all corners of the world on European ships (hence, the virus is known as an “Old World” virus). The virus is present worldwide but was first described in Korea, near Seoul. It is considered a rare pathogen among humans.

This is what makes the two cases reported-on by the CDC notable. Patient A was a healthy male, a 30-year-old maintenance worker who had “frequent rodent sightings at his workplace”. He contracted the disease in May 2018 and made full recovery after receiving treatment. Patient B was an unrelated case. This 37-year-old man with chronic kidney disease who worked as a dishwasher and plumber’s assistant contracted the disease in November 2018; it is unclear from what source. The CDC notes that he did not own any pets, had not recently travelled outside of the US, and was unaware of exposure to rodents at any point in his daily life. He also made a full recovery after receiving treatment.

The CDC believes these two cases were caused by the city-wide rat problem in Washington DC, which they explain has been worsening for years now.

“Rodent overpopulation in DC is well documented by increased complaints via the Citywide Call Center to the Rodent Control Program, and the DC Department of Health has amplified efforts to address this public health threat,” the CDC explains.

The cases serve as a reminder of the dangers of rat infestation in our cities, and should motivate the public to follow recommended hygiene practices to insulate themselves from the risk. Meanwhile doctors should keep in mind that the virus is active in the area and look out for signs of hantavirus infection in their patients.

Rats and pigeons are slowly replacing iconic species, and it’s our fault

When humans take over the environment, there are few winners — and many losers.

The snowy owl, once thought to number over 200,000 individuals, is now considered vulnerable. Image credits: Michael Gäbler.

Man-made

“Human use of the land (for agriculture and settlements) has a substantial negative effect on biodiversity globally,” researchers start out their study. Indeed, few corners of the world have remained untouched. Earth’s wilderness has slowly withdrawn in the wake of our relentless expansion.

When we set up cities and agricultural fields, we disturb a lot of varied ecosystems — ecosystems which host a number of species. As their homes are altered, many of these species find it impossible to adapt, and are eventually wiped out, much to the happiness of species like rats and pigeons, which thrive in man-made environments.

Researchers analyzed 20,000 animals and plants in 81 countries, finding that adaptable species which can live in a wide variety of ecosystems are the big winners, to the detriment of species well-adapted to a niched ecosystem. This is particularly concerning since these niched species include the likes of rhinos and tigers. Simply put, these are exactly the creatures you’d like to protect.

“We show around the world that when humans modify habitats, these unique species are consistently lost and are replaced by species that are found everywhere, such as pigeons in cities and rats in farmland,” said Dr Tim Newbold, a research fellow at University College London.

While this is hardly surprising, it indicates a few key areas where conservationists need to act.

“Our results are very important for biodiversity conservation because narrow-ranged species are typically at higher risk of extinction than widespread species. Furthermore, the shift to more widespread species may also affect ecosystem functioning by reducing both the contribution of rare species and the diversity of species’ responses to environmental changes among local assemblages,” the authors write.

Supermarket biodiversity

Meanwhile, the common wood pigeon is doing better than ever. Image credits: Tristan Ferne.

Think of it this way: imagine a neighborhood filled with small, local shops and restaurants. The moment a big supermarket chain comes in, you’ll start to see the shops decline. It’s a striking analogy, but a very fitting one, says co-author Prof Andy Purvis of the Natural History Museum, London.

“As small, independent retailers are going out of business, large chains dominate,” he said. “It makes all towns look the same, and it’s less easy to tell where you are. Likewise, people are affecting nature everywhere they go, and everywhere there are localised species which are struggling to make a living.”

This is also significant to us, as previous research has indicated that animals and plants occupying small areas tend to provide the most important ecosystem services, as well as the most vital roles in the food web.

The study “Widespread winners and narrow-ranged losers: Land use homogenizes biodiversity in local assemblages worldwide” was published in PLoS.

Rats successfully sniff out tuberculosis in children

In a new study, researchers show that rats can be trained to detect tuberculosis (TB) in children — and they have a higher accuracy rate than the basic microscopy test.

Several species of African pouched rats have been trained to sniff out TB or landmines.

The study was inspired by anecdotal evidence that people suffering from TB have a very slight, distinctive odor. The disease is caused by a bacteria called Mycobacterium tuberculosis. The bacteria usually attack the lungs, spreading through the air when a person with TB coughs, sneezes, or talks — so it makes sense that the process might come with a particular scent.

Unfortunately, methods for detecting TB are far from perfect, especially in impoverished areas like sub-Saharan Africa and South-East Asia, which are often most at risk of contagion and where the disease is quite prevalent. In these areas, a cheap smear test is commonly used.

The test relies on analyzing a sample of sputum — the yucky mixture of saliva and mucus coughed up from the respiratory tract. The accuracy of the test greatly relies on the quality of sputum sample used. Quite often (and this is especially true for young children), patients are unable to produce a good enough sample and therefore their TB might go undetected.

Lead author Georgies Mgode of the Sokoine University of Agriculture in Tanzania comments:

“As a result, many children with TB are not bacteriologically confirmed or even diagnosed, which then has major implications for their possible successful treatment,” he explained. “There is a need for new diagnostic tests to better detect TB in children, especially in low and middle-income countries.”

Mgode and his colleagues have previously worked on training African giant pouched rats (Cricetomys ansorgei) to pick up the scent of molecules released by the TB-causing bacterium. Now, they’ve compared the rats’ detection work with existing diagnosis methods.

They obtained sputum samples from 982 children under the age of five who had already been tested using a microscopy test at clinics in the Tanzanian capital of Dar es Salaam. From the smear test, 34 of them were found to have TB, but the rats identified a further 57 cases which were confirmed by a more complex analysis method (the light emitting diode fluorescence microscope). In other words, rats successfully found 68% more cases of TB infection

“This intervention involving TB screening by trained rats and community based patient tracking of new TB patients missed by hospitals enables treatment initiation of up to 70%. This is a significant proportion given that these additional patients were considered TB negative in hospitals, hence were initially left untreated,” adds Mgode.

The news has already been passed to relevant clinics, and plans are underway for a broader detection campaign. The infected children in the study have been contacted for treatment.

The same type of rats has also been used to sniff out landmines.

Journal Reference: Mgode, G.F. et al. Pediatric tuberculosis detection using trained African giant pouched rats. DOI:10.1038/pr.2018.40

Giant (adorable?) species of rat discovered in the Solomon Islands

Mammalogist Tyrone Lavery had heard rumors of a giant, possum-like rat that lived in the trees, but he was still surprised when he encountered it.

What, were you expecting a beautiful bird or something? An illustration of the new species, Uromys vika. Image: Velizar Simeonovski, The Field Museum

“When I first met with the people from Vangunu Island in the Solomons, they told me about a rat native to the island that they called vika, which lived in the trees,” says Lavery. “I was excited because I had just started my Ph.D., and I’d read a lot of books about people who go on adventures and discover new species.”

Locals told Lavery that the rat was large enough to crack open coconuts with its teeth. He first heard these rumors in 2010, but after ten failed expeditions to the islands, he almost gave up. This is a common problem biologists face in the Solomon Islands: despite being really exotic, it’s hard to find new species. Each island has something new and interesting to offer, but many of those things have already been discovered — or have been killed off since. Numerous species were discovered in the late 1800s or early 1900s, but many of these species were spotted again. Lavery feared this was the case with the vika, extinct before it could even be studied. The ongoing deforestation in the area was not an encouraging sign.

“I was sure that vika existed, but I was very worried it may have been a species that was already extinct, and that the signs of vika people were telling me about — for example, chewed ngali nuts — were merely from the introduced rats,” Lavery said. “After some exhausting attempts to find it, I was on the verge of giving up.”

He even started considering that the locals just called regular (big) rats vika, but he didn’t give up the search. The problem is, Lavery says, that it’s always more difficult to find tree-dwelling animals. When you’re looking for something on the ground, you’re basically looking for it in 2D. When you’re looking up in the trees, there’s a whole new extra dimension to consider, and that makes things much harder.

Nuts bearing the characteristic tooth-marks of Uromys vika. Credits: Courtesy of Tyrone Lavery, The Field Museum.

Eventually, he found one. Scurrying off from a felled tree, it was immediately obvious that there was something different about this rat.

“The new species, Uromys vika, is pretty spectacular — it’s a big, giant rat,” said Lavery, a post-doctoral researcher at The Field Museum in Chicago and the lead author of the Journal of Mammalogy paper announcing the rat’s discovery. “It’s the first rat discovered in 80 years from Solomons, and it’s not like people haven’t been trying — it was just so hard to find.”

Lavery carried out DNA tests to be sure he’d found something different, and he also consulted the locals to confirm it was the vika they knew. “This project really shows the importance of collaborations with local people,” he says. Too often, local stories are discarded as myths or exaggerated anecdotes. It’s true that this is often the case, but sometimes, it can lead to spectacular discoveries.

From its head to the end of its tail, the vika measures 50 centimeters (about a foot and a half), and weighs more than 1 kilogram (2.2 pounds). It hasn’t been witnessed cracking coconuts, but they do have a penchant for chewing circular holes into nuts to get at the meat. Its giant size and unusual lifestyle can be traced to the peculiarities of the Solomon Islands. The islands are biologically isolated from one another, and often feature different types of habitats which force the dwellers to adapt. Vika’s ancestors probably drifted from the mainland on logs or other vegetation. They must have looked like regular rats, but once in the new habitat, they adapted into the wonderful species we see today.

Well I think it’s wonderful, OK? Credits: Courtesy of Tyrone Lavery, The Field Museum.

Unfortunately, things aren’t looking too good for the newly-found vika. Logging and the destruction of its rainforest habitat could spell certain doom, and its brilliant adaptation could amount to nothing.

 “It’s getting to the stage for this rat that, if we hadn’t discovered it now, it might never have gotten discovered. The area where it was found is one of the only places left with forest that hasn’t been logged,” says Lavery. “It’s really urgent for us to be able to document this rat and find additional support for the Zaira Conservation Area on Vangunu where the rat lives.”

Typical rainforest landscape from the Solomon Islands. Credits: Department of Foreign Affairs and Trade.

Considering how rare it is to find a new mammal, it’s extra important that we preserve the vika. Like it, many other species likely await discovery in the lush Solomon rainforest, and unfortunately, many that we will never discover because we’ve already wiped them out. But even that doesn’t tell the whole story. Conserving the species, Lavery emphasizes, has more than a biological component: it’s also important culturally. Locals have songs about it, children are taught nursery rhymes with the vika, and all of that could go away.

Bramble Cay melomys. Credit: Wikimedia Commons

Great Barrier Reef rodent becomes first extinct mammal at the hand of climate change

Bramble Cay melomys. Credit: Wikimedia Commons

Bramble Cay melomys. Credit: Wikimedia Commons

Great Barrier Reef’s only endemic mammal, the Bramble Cay melomys, is now officially extinct, scientists say. The rat-like rodent occupied a very confined habitat spanning an area no larger than a football field called Bramble Cay, a minuscule atoll in the northeast Torres Strait, Australia. Although pressured by human hunting and competition with other species, what ultimately killed off the species were surging sea waters and rising tides triggered by man-made climate change — the first mammalian species wiped out of the evolutionary history books in this manner.

The small coral cay where the rodent used to live was just 340m long and 150m wide, sitting only three meters above the sea level, off the north coast of Queensland, Australia. When Europeans first settled Queensland around 1845, records show they proceeded hunting the ‘rats’ with bow and arrow. By 1978, only a couple hundred specimens were recorded during field surveys, which were quite accurate given the minute area. Around this time the rodent was listed as endangered.

The last melomys were sighted in 2009, and despite extensive surveys in the area, no specimen was found even to this day. There might still be some odd rodents lurking in some crevices, but that seems unlikely given that their habitat is often flooded nowadays, which left them without food, shelter or any kind of livelihood. Natalie Waller and Luke Leung from the University of Queensland now claim with high confidence that the melomys are extinct, in a recent review.

“For low-lying islands like Bramble Cay, the destructive effects of extreme water levels resulting from severe meteorological events are compounded by the impacts from anthropogenic climate change-driven sea-level rise,” the authors said in their report.

“Significantly, this probably represents the first recorded mammalian extinction due to anthropogenic climate change,” they added.

Unfortunately, this might just be one of the first in many yet to come. A 2013 report notes 17 percent — one in six — of threatened and endangered species are at risk from rising sea levels in the United States alone. As for Australia’s coral reef, things are pretty bleak. Half of the Northern Great Barrier Reef is now dead at the hand of global warming which triggered massive coral bleaching.

hero_rat

Hero Rats detect landmines and TB for a living

hero_rat

CREDIT: APOPO

Though its last war ended in 1975 once with the retreat of the last American forces, Vietnam is still riddled with land mines that take their toll even decades later. More than one-third of the land in six central Vietnamese provinces is still littered with land mines and unexploded bombs from the Vietnam War, and in the past 39 years since the war ended more than 42,000 people have been killed by this lost ordinance. The same is true in countries like Thailand, Angola, Cambodia, Laos or most sub-Saharan African nations who have been devastated by countless internal feuds and struggles for power.

Detecting landmines can be difficult, dangerous and expensive, but an unsung hero is set to change all this — the African giant pouched rat.

In 1997, the Anti-Personnel Landmines Detection Product Development (APOPO) was launched, tasked with training so-called Hero Rats that can detect landmines and even tuberculosis with almost 100% accuracy.

Since 2000, hundreds of trained and accredited rats found 1,500 buried land mines across an area of 240,000 square meters in Tanzania, and 6,693 land mines, 26,934 small arms and ammunitions, and 1,087 bombs across 9,898,690 square meters in Mozambique.

Hero Rat receiving a treat after a successful training round. Photo: APOPO.

Hero Rat receiving a treat after a successful training round. Photo: APOPO.

The project was so successful that a spin-off project was launched to further exploit the rats’ uncanny sense of smell, training Hero Rats for tuberculosis detection. Only 54 rats have been trained for this role so far, but these are already working in 19 TB clinics in Dar es Salaam, Tanzania, where they’ve screened 226,931 samples and identified 5,594 TB patients since 2002. A rat can detect more TB samples in 10 minutes than a lab technician in a whole day!

Hero Rat detecting TB samples in the lab. Photo: APOPO

Hero Rat detecting TB samples in the lab. Photo: APOPO

As you might have guessed from these pictures, these aren’t your typical rats. We’re all familiar with house rats (Muridae), but these animals belong a different family of species altogether called Nesomyidae. Adult African giant pouched rats grow to be around 0.9 meters (3 feet) long and 1.4 kilograms (3.1 pounds) in weight. They also have a sort of storage space inside their cheeks so they can keep food for later use. Yup, oversized gerbils!

Training rats for this sort of task isn’t easy, though. It takes nine months for a pup to grow into a Hero Rat, and not all of them make the winning lot.

The training first starts with making the rats feel adjusted with real working environments by exposing them to numerous stimuli like radios, flowers, coffee, and different surfaces such as grass, concrete, and soil.

“During one week, I will be taking the pups outside the kennels for about 20 minutes every day. I let them smell different odours like tea, coffee and oil, they get to hear different sounds like a ringing phone and human voices and they get to wander around on different surfaces as sand, wood, grass and concrete,” caretaker Albert Carol says at the APOPO website. “I make sure they are exposed to all kind of smells, textures and sounds, but especially to being handled by people. Every individual pup gets plenty of attention and learns to be held and carried by the trainers.”

The video below gives you a glimpse of how Hero Rat training looks like.

It’s important to note that the Hero Rats don’t get harmed. Anti-personnel mines are triggered when a certain pressure corresponding to an equivalent weight is sensed. Being too lightweight, the rats don’t trigger the mines, but they can sense the TNT and quickly alert professional who later diffuse them.

If you’d like to support the project, you can donate as little as $7 per month. You’ll then be granted access to a log on the APOPO website which will inform you of how your pet rat is doing in training half-way around the world.

rats

Why rats can’t vomit, and how they make up for it

Sure, vomiting can be gross, but it’s also an essential survival reflex that’s saved countless lives. Humans are very fortunate to able to vomit, unlike other species like rats. They don’t burp or experience heartburn, either. In fact, it seems like rats have little to any reflexes — not the kind that saves your gut from poisons, bad drugs, motion sickness, radiation or hearing Donald Trump talk on television.

rats

Credit: Wikimedia Commons

[panel style=”panel-primary” title=”What’s vomiting” footer=””]Vomiting, or emesis, is the reflexive act of ejecting stomach contents forcefully through the mouth by coordinated muscular contractions.

Vomiting, or emesis as doctors call it medically, is the body’s reflex of ejecting stomach contents forcefully through the mouth. Vomiting is distinct from regurgitation. Unlike regurgitation which is a passive, effortless expulsion of the stomach’s content, vomiting is an active reflex which involves complex muscle coordination. Occasionally rats will regurgitate, but they can’t vomit.

In humans, the vomiting signal is triggered  by a group of nuclei in the brainstem. This instructs the muscles surrounding the stomach to contract, the diaphragm to spasm inward and downward, and the esophagus to open.[/panel]

By lacking gut reflexes, rats may have trouble swallowing food. At times, a rat might seem like it’s choking, straining intently by pulling the chin down toward the throat and flatting the ears. The rats are still able to breathe though and true choking is very rare. Sometimes, a rat will expel some of the swallowed food, but that’s not vomiting.

[panel style=”panel-danger” title=”The body’s protection system against toxins” footer=”Davis et al. (1986)”]

 

  • First line of defense: Avoidance of certain foods due to smell or taste cues
  • Second line of defense: Detection of toxins in the gut followed by nausea (prevents further consumption) and vomiting (purges the body of already ingested toxin)
  • Third line of defense: Detection of toxins in the circulation by a sensor in the central nervous system, also followed by vomiting.

[/panel]

Biologically, a rat is unable to vomit because of a powerful and effective gastroesophageal barrier, research shows. This barrier consists of crural sling, the esophageal sphincter, and the intra-abdominal esophagus. Researchers found that the pressure at the two ends of this barrier is greater than the pressure found in the thorax during any phase of the breathing cycle. This pressure, thus, makes it impossible for rats to reflux.

More specifically, rats are unable to vomit because they can not open the crural sling at the right time. Rats also lack the neural wiring required to coordinate the muscles involved in vomiting mentioned earlier.

While they do lack the ability to vomit, an integral part of many species’ defence mechanisms against toxins, rats seem to have adapted by strengthening their first line of defence. Researchers note that rats have a very keen sense of smell and taste and will easily avoid foods which might cause a vomiting response in other species. Some speculate that vomiting has become redundant and lost over time because rats seem to avoid dangers at the hand of toxins so well. Alternatively, rats developed a hyper-sensitive food avoidance to compensate for the inability to vomit. It’s not clear at the moment which came first.

Rat toxin avoidance isn’t full proof, though (remember, rat poison!). At times, a rat will become intoxicated and experience nausea. Luckily, the rat developed an alternative to vomiting by consuming non-nutritive substances. This behaviour is called pica. When rats feel nauseous, they start eating things like clay, dirt, hardwood bedding, all sorts of materials they wouldn’t consider ingesting in normal conditions. These non-nutritive substances may help dilute the toxin’s effect, so pica can be thought of as part of the rat’s second line of defence.

As a parenthesis, some human communities also engage in pica practice. When researchers went to Madagascar to study  760 participants from the Makira Protected Area,  they found 63 percent of adult males engaged in pica and amylophagy.

Other common animals that can’t vomit include rabbits, horses, guinea pigs or the Japanese quail. So, next time you throw up consider yourself blessed.

Fossils of huge rats found in Asia

Archaeologists have discovered fossils of rats 10 times bigger than modern rats. Working with the Australian National University (ANU), the team made the findings in East Timor, a former Portuguese colony in south-east Asia.

Dr. Julien Louys holds the jaw bone of a giant rat species discovered in East Timor, comparing it to the same bone of a modern rat. Image via Stuart Hay, ANU.

Dr Julien Louys of the ANU School of Culture, History and Language said these are the largest rat fossils ever to be found, and by all accounts, these are the biggest rats to have ever existed.

“They are what you would call mega-fauna. The biggest one is about five kilos, the size of a small dog,” Dr Louys said. “Just to put that in perspective, a large modern rat would be about half a kilo.”

Researchers were actually trying to track the earliest human movement through Southeast Asia when they found the fossils, and now they are working on figuring out just why the rats got so big, and what drove them extinct.

The earliest evidence of humans in East Timor dates from around 46,000 years ago, and they lived alongside rats for thousands of years. In fact, these early humans were actually eating the big rats.

“We know they’re eating the giant rats because we have found bones with cut and burn marks,” he said.

The cause of the rat extinction may have been, as it often happens, humans. As humans became more and more advanced, they started to destroy the habitats of rats, driving them off the island.

“The funny thing is that they are co-existing up until about a thousand years ago. The reason we think they became extinct is because that was when metal tools started to be introduced in Timor, people could start to clear forests at a much larger scale.”

Now, as they’re trying to track the movement of humans, they are also analyzing the impact the humans had.

hog-nosed rat

Meet the hog-nosed rat, a new species of mammal

While surveying the island of Sulawesi right in the center of Indonesia, a group of researchers came across a previously undocumented species of rodent. It was pretty easy too, considering the animal’s uncanny appearance: what would otherwise look like a normal looking rat, but with the nostrils of a hog.

hog-nosed rat

Image: Museum Victoria

Kevin Rowe, a curator for the Museum Victoria, was out on an expedition with other colleagues from Indonesia, Australia and the US trekking through the lush mountainside of the island. The team enlisted locals to help them set traps and collect samples. It took them no less than six weeks to reach the targeted area of the forest on the island.

The hog-nosed rat also has longer teeth and tail than other rodents. Image: Museum Victoria

The hog-nosed rat also has longer teeth and tail than other rodents. Image: Museum Victoria

They weren’t on the lookout for Hyorhinomys stuempkei, the hog-nosed rat, but they knew there was a good chance they’d find some new species to science on the island. Small as it is, Sulawesi is a biological treasure trove where many distinct species live and because it’s isolated, most of these animals are unique! For instance, last year the same team discovered amphibious and toothless rats. The rich diversity encouraged them to seek more. To their great satisfaction, they came across Hyorhimoys – a spectacular new species of rat.

Besides its hog-like appearance, there are other features that set it apart from other rats though you need to have a biologist’s trained eye. Its ears are longer and the mouth is smaller. The teeth are lower and resemble more those of a shrew rat. Also, the pubic hairs are long and extended reminiscent of Australian mammals.

“I am still amazed that we can walk into a forest and find a new species of mammal that is so obviously different from any species… that has ever been documented by science,” said Rowe.

An illustration of a rat wearing the geomagnetic device (credit: Norimoto and Ikegaya)

Blind rats ‘sense’ their location after a geomagnetic compass was strapped to their brains

Blind rats learned to navigate mazes just as well as those that could see, after scientists strapped a simple geomagnetic compass – the kind that’s found in your smartphone – fitted with electrodes directly onto their brains. Though they’re not naturally equipped to sense magnetic fields, the rats’ brains demonstrated tremendous plasticity and effectively incorporated a new sense! We can only presume this is possible in the case of humans as well, so the team from Japan which made the study believes blind people could incorporate a similar device – minus the brain hack. There are other alternatives after all, like say an iPhone app that acoustically alerts the blind person which way to turn or a sensor directly fitted into a walking cane.

An illustration of a rat wearing the geomagnetic device (credit: Norimoto and Ikegaya)

An illustration of a rat wearing the geomagnetic device (credit: Norimoto and Ikegaya)

Yuji Ikegaya and Hiroaki Norimoto, both  of the University of Tokyo, wanted to see if blind rats could have their ability to navigate the world restored, but not by making them see. Instead, one a more fundamental level, they sought to restore their allocentric sense – the sense that allows animals to recognize their position relative to the environment. So, instead of eyes, why not graft rats with a geomagnetic compass. The device was connected with  two tungsten microelectrodes for stimulating the visual cortex of the brain. The lightweight package could be turned on or off remotely and included rechargeable batteries. Once attached to the brain, the sensors would read the direction of the rat’s head and would send pulses relaying information that told the rat which direction he was facing – north or south, for instance.

Geomagnetic sensor system, with connection to the primary visual cortex (adapted) (credit: Hiroaki Norimoto and Yuji Ikegaya/Current Biology)q

Geomagnetic sensor system, with connection to the primary visual cortex (adapted) (credit: Hiroaki Norimoto and Yuji Ikegaya/Current Biology)

The rats were then trained to find food in a T-shaped maze, then on with more complex shapes. After tens of trials, the rats with the geomagnetic sensors perform indistinguishably from the rats that could see, as reported in  Current Biology.

“We were surprised that rats can comprehend a new sense that had never been experienced or ‘explained by anybody’ and can learn to use it in behavioral tasks within only two to three days,” Ikegaya says.

“We demonstrated that the mammalian brain is flexible even in adulthood — enough to adaptively incorporate a novel, never-experienced, non-inherent modality into the pre-existing information sources.”

The world is a far richer place than we can imagine with our puny five senses. Imagine sensors that could be fitted to your brain to effectively sense infrared light, or ultrasound. Sixth sense? How about 20th sense? These is definitely some food for thought for any biohacker.

 

 

norwegian rat

Rats reward their friends for help – first such act seen among non-humans

Norwegian rats know how to keep their friends close. A new study found they reward other rats for their help even though there’s no immediate gain at hand as a result of this behavior. Called direct reciprocation, this is the first time something like this has been recorded by science outside human interactions.

Help a brother out

norwegian rat

Image: MikeSPb/istockphoto.com)

Sure there are many animals that assist and cooperate with another, including rats of course, but until now we had yet to seen any non-human animal reward a peer for his help. At least, we’ve yet to see truly compelling evidence, not just some “accidents”. At first glance, it might not seem like such a big deal. If you study the framework closer, however, you’ll then see that reciprocation and altruism are very complex cognitive behaviors. Some of the necessary psychological ingredients for reciprocation include: numerical quantification, time estimation, delayed gratification, detection and punishment of cheaters, analysis and recall of reputation, and inhibitory control. Evidence of reciprocation in the animal kingdom has been scarce and far from conclusive, but a team at University of Bern in Switzerland wanted to test this long standing conundrum.

The researchers thought of Norwegian rats as good candidates, since they’re rather socially intelligent and easy to observe. Their experiments were based on exploiting one of the rats’ biggest weakness – bananas! Female rats were introduced in the experimental chamber in pairs, and each would take turns either sitting in a cage with nothing to interact with or in an enclosure with two sticks. One stick would send the caged rat some tasty bananas, while the other would send the not so tasty carrots. This way, the receiving rat could recognize the offering rat as being very helpful (bananas!) or just plain helpful (eat your veggies — meh).

Then the rats would switch roles – the helped was now the helper.  So the rats on the receiving end were now able to pull on a stick that would deliver cereal flakes to a certain helper. The rats that had given bananas generally received cereal more quickly and more often than carrot-givers. In the same vein, the rats that had given carrots got cereal less often than the banana-givers did, according to Ralph Martins writing for National Geographic. Findings appeared in the journal Biology Letters.

Is what we’re seeing a genuine example of direct reciprocation? Michael Taborsky, a behavioral ecologist at the University of Bern in Switzerland, believes this is the case. “Two elements are involved: recognizing an individual, and responding to the quality of service,” Taborsky says.

Both of these elements were proven and documented previously in rats, but this only means that it’s possible and not quite a genuine proof per se.  Thomas Zentall, an animal behaviorist at the University of Kentucky in Lexington, thinks on the other hand that the rats simply associate the helper with the food. In their minds, according to Zentall, pulling on the stick when the banana-giver is present might bring bananas. Back to Taborsky, he says that this is highly unlikely since rats were shown to clearly distinguish between delivering food to others or to themselves.

While researching this article, I ran across another possible example of reciprocal altruism in the animal kingdom. In their book, “From Monkey Brain to Human Brain: A Fyssen Foundation Symposium”, the authors discuss various possible examples of such behavior. One subject deals with vampire bats which can live up to 20 years and spend much of their time in large, stable social groups where there are multiple opportunities to interact with the same individual. As the name implies, the vampire bat drinks blood in order to survive. Just 60 hours without a bloody meal makes a bat die. As you might imagine, there are some slow days for vampire bats, but luckily this is where their stable social group comes in. If the bat is unable to hunt its own blood, it might receive it from some other bat who would regurgitate the undigested blood. But blood is valuable and giving it up comes at a cost – hence it is an act of altruism.

In 1984, Gerarld Wilkinson published a paper in Nature in which he reported how most of these cases of blood regurgitation were between those of the same kin. Of course, this is something we’ve seen a lot of times before. Despite coming at a cost, this sort of behaviour is seen as an investment in your own gene pool. Some regurgitation, however, were delivered to non-kin – so what’s up with that? Obviously, this sort of cases require more attention. There are two possibilities: either the bats mistook the other hungry blood thirsty bats for kin or they purposefully gave blood to non-kin with the expectation that they would receive blood back in the future.

Whatever’s the case, this latest study on Norwegian rats gives to show that animal reciprocity deserves a second look. Needless to say, us humans take ourselves and our superior cognitive abilities way too seriously. We’re not all that different.

Exonerate the rats – it was gerbils that brought the Black Plague

It’s always the cute ones – a team of Norwegian researchers found that the Black Plague, which arrived in Europe in the 14th century and wiped out up to 200 million people was brought by gerbils, not by rats.

Gerbils may be responsible for bringing the Black Plague to Europe. Image via Pet Info Club.

The Black Plague is one of the most devastating epidemics humanity has encountered, originating in Central Asia and traveling along the Silk Road, reaching today’s Turkey and Ukraine. From there, it spread to the Mediterranean area and across the entire continent, wiping out 30-60% of the continent’s population. Until now, scientists believe the agents which carried the pathogen were rats – but Prof Nils Christian Stenseth, from the University of Oslo claims othwerwise:

“If we’re right, we’ll have to rewrite that part of history.”

The thing is, in order for rats to thrive and carry the disease across the entire continent, you would need some specific climatic conditions.

“For this, you would need warm summers, with not too much precipitation. Dry but not too dry. And we have looked at the broad spectrum of climatic indices, and there is no relationship between the appearance of plague and the weather.”

The emergence of the disease in Europe. Image via Wiki Commons.

In order to see if the climate was suitable for rats, he and his team analyzed 15 tree ring records, which carry with them the conditions in certain years. Tree ring analysis can be used to determine certain aspects of past climatic – including the amount of rain. They then compared these tree rings with 7,711 historical plague outbreaks to see if the weather conditions were right. As it turns out – they weren’t.

However, their results indicated spectacular conditions for another plague-carrying rodent – the giant gerbil – to thrive. They believe this is the main carrier of the Black Plague.

“We show that wherever there were good conditions for gerbils and fleas in central Asia, some years later the bacteria shows up in harbour cities in Europe and then spreads across the continent,” Prof Stenseth said.

The conditions he is referring to is a wet spring followed by a warm summer – something which gerbils love, and rats – not  so much.

“Such conditions are good for gerbils. It means a high gerbil population across huge areas and that is good for the plague,” he added.

The team is now working to confirm their results with DNA analysis. If this checks out, then we can exonerate rats for causing one of the biggest epidemics mankind has faced.

“We originally thought it was due to rats and climatic changes in Europe, but now we know it goes back to Central Asia.”

Journal Reference: Boris V. Schmida, Ulf Büntgen, W. Ryan Easterdaya, Christian Ginzlerb, Lars Walløee, Barbara Bramantia, and Nils Chr. Stensetha. doi: 10.1073/pnas.1412887112

Footage of a paralyzed rat using his hind legs, which normally should have been completely numb. This from experiments performed last year, so this is an old implant - not the newly developed e-Dura. Image: CNET

Paralyzed rats regain use of hind legs with flexible spinal cord implant. Humans to follow

Footage of a paralyzed rat using his hind legs, which normally should have been completely numb. This from experiments performed last year, so this is an old implant - not the newly developed e-Dura. Image: CNET

Footage of a paralyzed rat using his hind legs, which normally should have been completely numb. This from experiments performed last year, so this is an old implant – not the newly developed e-Dura. Image: CNET

Swiss scientists demonstrated a flexible ribbon-like implant that attaches itself to a paralyzed rat’s spinal cord, allowing the animal to walk again. The prosthetic, described by foremost experts in the field as ‘remarkable’, works by delivering timed electrical impulses and drugs along the spinal cord. In this particular case, rats aren’t that different from humans, and true enough clinical trials are now one step closer. In the future, paralysis might just be another word for “walking funny.”

A breakthrough in medicine

The technology was first introduced by researchers at the Ecole polytechnique federale de Lausanne, Switzerland last year, when it was shown how a rat with a severed spinal cord could walk again after a system of electrical impulses and chemical reactions was introduced.  The brain moves the body by sending electrical signals down the spinal cord and into the nervous system. When the spinal cord is severed, the signals can no longer reach that part of the spine, paralyzing that part of the body. The idea is to direct electrical impulses below the cut, where signal from the brain discontinued. This is done via electrodes that take the place of the brain signal, along with neurotransmitting drugs to reanimate the nerve cells beneath the injured tissue. If you find this amazing, you’re not alone. Paralysis might become a thing of the past in just a few decades.

This is how the flexible e-Dura implant looks like. The implant is so effective because it mimics the soft tissue around the spine so that the body does not reject its presence. Image: EPFL

This is how the flexible e-Dura implant looks like. The implant is so effective because it mimics the soft tissue around the spine so that the body does not reject its presence. Image: EPFL

In practical terms, however, a surface implant on a human’s spinal cord is extremely tricky. Because it’s rigid, the constant friction causes local inflammation, damaging the surrounding area. The latest updates features a flexible implant specifically designed to integrate with the patient’s spine, minimizing the risk of rejection and further damage. Called E-Dura, the implant mimics the soft tissue around the spine – known as the dura mater – reducing the risk of inflammation, friction and abrasion.

[RELATED] Paralyzed rats regain control of their bladder

“Our e-Dura implant can remain for a long period of time on the spinal cord or cortex,” said Professor Stéphanie Lacour.

“This opens up new therapeutic possibilities for patients suffering from neurological trauma or disorders, particularly individuals who have become paralyzed following spinal cord injury.”

After implanting e-Dura in rats, researchers found there was no sign of damage or rejection following two months of observation. It goes without saying the the rats could walk once the implant was set.

e-dura2

The implant is made of silicon and covered with gold electric conducting tracks that can be pulled and stretched along with the silicon material. The electrodes, a new composite made of silicon and platinum microbeads, can be pulled in any direction. The two components act together and direct electrical signals to the spinal cord in the same manner as the brain would. Meanwhile, tiny microfluid channel embedded in the implant deliver neurotransmitter drugs.

“Soft flexible nerves connected to unyielding silicon and metal – the combination has spawned many a Hollywood cyborg,” wrote science writer Robert Service in Science.

“The implants Lacour’s team created still have to be wired to the out- side world to operate, but she and her colleagues are designing wireless versions of the technology. Watch out, Hollywood, reality is catching up.”

It’s heartwarming to hear that this isn’t the only effort that seeks to abolish paralysis. There are many projects worldwide hard at work developing the next generation of implants and drugs that will make paralysis a thing of history. For instance, another group at Cambridge University has restored movement in the hind legs of 23 dogs after they transplanted nerve cells from the animals’ noses.

The human trials may start as early as June of this year, at a special facility called the called the Gait Platform, housed in the University Hospital of Lausanne, Switzerland. The e-Dura implant was described in a paper published in Science.

Mothers teach babies fear through smell

Babies can learn what to fear from the first days of life simply by smelling their distressed mothers, a new study has shown. This doesn’t only work after the pregnancy, but also during it and even before – if a mother experiences something specific which makes her fearful.

It’s the first direct observation of this kind – University of Michigan and New York University researchers studied mother rats who had learned to fear the smell of peppermint – theyalso showed that the mothers passed this fear on to their offspring and also pinpointed the exact area of the brain where the learning of fear takes places in the first days of life.

This may help explain something which has puzzled biologists for decades – how is it that a mother’s traumatic experiences are passed on to her offspring?

“During the early days of an infant rat’s life, they are immune to learning information about environmental dangers. But if their mother is the source of threat information, we have shown they can learn from her and produce lasting memories,” says Jacek Debiec, M.D., Ph.D., the U-M psychiatrist and neuroscientist who led the research.

So in a way, even before they can actually accumulate knowledge of their own, they get a taste (or rather, a smell) of their mothers’ experience.

“Our research demonstrates that infants can learn from maternal expression of fear, very early in life,” he adds. “Before they can even make their own experiences, they basically acquire their mothers’ experiences. Most importantly, these maternally-transmitted memories are long-lived, whereas other types of infant learning, if not repeated, rapidly perish.”

In order to figure this out, they devised an experiment which involved making mother rats fear the smell of peppermint by exposing them to non harmful, but unpleasant electric shocks while they smelled the scent, before they were pregnant. Then after they gave birth, the team exposed the mothers to just the minty smell, but didn’t deliver the shocks. They found that newborns quickly picked up on the fear – even though they had no direct reason to fear it. They could learn their mothers’ fears even when the mothers weren’t present.

Using special brain imaging, and studies of genetic activity in individual brain cells and cortisol in the blood, they found that this learning takes place in the lateral amygdala. The amygdala is present in virtually all evolved mammals, playing a complex role in the in the processing of memory, decision-making, and emotional reactions.

Researchers now hope to conduct the same kind of study for mothers and their babies, but they have every reason to believe they will get similar results.

Drawing illustrates a rat with a BMBI attached to the skull retrieving food. Photo courtesy: Case Western Reserve University

Brain-computer interface restores brain connectivity in injured rats

Drawing illustrates  a rat with a BMBI attached to the skull retrieving food. Photo courtesy: Case Western Reserve University

Drawing illustrates a rat with a BMBI attached to the skull retrieving food. Photo courtesy: Case Western Reserve University

Case Western Reserve University and University of Kansas Medical Center  researchers recently report they’ve devised a neural prosthetic that partially restored brain connectivity in rats whose brains were injured. Effectively, the rats regained their functional behavior and were able to perform tasks similarly to normal rats, something that otherwise wouldn’t had been possible. The research gives hope that the interface may be implanted in patients suffering from severe brain trauma, consequent of accidents, war, neuro-degenerative diseases or strokes, and help them live a normal life.

Some 1.5 million people in the U.S. alone suffer from traumatic brain injuries (TBI), while there are a reported  800,000 stroke victims. These patients have neural functions impaired and have great difficulty leading a normal life, either suffering from motor weakness, psychiatric disorders or even paralysis. Most of these issues are due to poor or even lack of connectivity between some parts of the brain. Remember the alien hand syndrome?

The team of researchers, led by Randolph J. Nudo, professor of molecular and integrative physiology at the University of Kansas, devised a  closed-loop microelectronic system called   a brain-machine-brain interface (BMBI) that bridges the areas of the brain that had lost connectivity, stimulating recovery.

The microelectronic BCBI system. credit: Case Western Reserve University

The microelectronic BCBI system. credit: Case Western Reserve University

Their device was tested on rat models, whose brains were mapped out. The researchers disconnected the anterior and posterior parts of the brain that control the rat’s forelimbs and then implanted at the microelectronic system atop of the animals’ heads. The electrodes of the device, which is smaller than a quarter, were carefully implanted in the two parts of the brain.

Making rat brains whole again

The BMBI works by first recording and amplifying neural signals from the anterior (front) of the brain. These signals come in various forms, and an embedded algorithm processes signal spikes and separates them from useless signals like noise. The device then sends an electrical current corresponding to each neural spike to the posterior part of the brain, stimulating neurons and effectively re-connecting the two parts of the brain.

After using the prosthetic for two weeks continuously, the researchers found that the rat models  had recovered nearly all function lost due to injury, successfully retrieving a food pellet close to 70 percent of the time, or as well as normal uninjured rats. Control subjects that received random stimuli retrieved that pellets 50 percent of the time, while disabled rats who received no neural prosthetic whatsoever only managed 25 percent of the time.

The results look truly promising, and if these can be recreated in human subjects as well, then a slew of mind-numbing disorders could be addressed.

“This technology could have direct clinical application for restoring neural communication in the brain, and thus, for restoring function,” Nudo explained to KurzweilAI in an email interview.  “Initial clinical targets will include focal stroke or traumatic brain injury (TBI) for motor impairments.

“However, this technology may be effective for a variety of neurological syndromes that are thought to be related to disruption of cortical communication, such as disconnection syndromes. This could include applications for cognitive and psychiatric disorders, as well. From a practical standpoint, it is theoretically possible that the target locations for the technology could be identified using modern neuroimaging techniques, such as diffusion tensor imaging, or resting state connectivity.

What’s interesting is that the there’s a sound possibility that such a system doesn’t necessarily have to be kept connected to the brain for life. It could be used for a certain time frame, after which the brain would be able to resolve its connectivity by itself. More work needs to be done, according to the authors, in order to see how long these time windows need to be and how effective recovery is post-device extraction.

“The innovation can be commercialized immediately, from the standpoint of initiating further development of a human device, navigating the FDA process for submitting an investigational device exemption (IDE), and identifying the most appropriate clinical population for first-in-human studies,”  Nudo said. “Realistically, the pace of this process is constrained only by available financial resources. But, first-in-human studies could potentially take place in the 5–10 year time frame.”

A brain prosthetic

Photo: Case Western Reserve University

Photo: Case Western Reserve University

Of course, this isn’t the first brain-computer interface. Previously, ZME Science reported on a slew of mindblowing innovations.  The authors of the paper published in the journal Proceedings of the National Academy of Sciences explain how their closed-loop system is different.

“This brain-machine-brain interface (BMBI) neuroprosthesis is among the first examples of closed-loop neural interfaces that combine neural recording, neural signal processing and neuromodulation functions for real-time, bidirectional interfacing with the central nervous system, and is the first such example that is applied to facilitate rapid and substantial recovery from TBI,” said Pedram Mohseni,  professor of electrical engineering and computer science at Case Western Reserve.

“Other technologies that have been used to modulate brain activity in neurological conditions have been open-loop approaches (epidural stimulation, transcranial magnetic stimulation, transcranial direct-current stimulation). In addition, open-loop modulation is typically paired with rehabilitative therapy.

“In clinical trials, the rehabilitative therapy is often found to be the main factor, and not the neuromodulation technology. With this new closed-loop microdevice, at least in the rat model of TBI, no rehabilitation was required. The ‘training’ was induced in the neural pathway that was the target of the microdevice.”

rat-navigation

Virtual reality for rats shows how different brain functions cooperate during navigation

Some people are better navigators than others, i.e. men better than women. Whether you can make your way effortlessly through the woods to reach a safe house or get seemingly lost on your way home from a different bus stop, it doesn’t make that much of a different at a sensory level. Navigation is often taken for granted, but the truth is it’s one of the most complex neurological function of the brain, one which requires a great of energy and complexity. This fundamental skill is paramount to avoiding threats and locating food (the reward), and through the mechanisms of evolution which promotes survival traits, it has steadily improved generation after generation.

rat-navigation

Rat in virtual reality. (c) UCLA

The connection between spatial reasoning and reward (anticipating and actually locating food) has been very difficult to measure, mainly because current technology doesn’t permit to simultaneously study both while an animal was moving. A team of researchers at UCLA have devised, however, an ingenious multisensory virtual world for rats in order to understand how the brain processes the environmental cues available to it and whether various regions of the brain cooperate in this task.

Rats are inserted in a sort of cube, with displays on each side, and are trained to navigate their environment that changes each time through a trackball to reach their reward (sugar water). Since the animal moves on the trackball, it actually is stationary, but is offered the illusion of movement aided by visual and auditory cues.

Previously, the same team of  UCLA researchers, led by neurophysicist Mayank Mehta, discovered how individual brain cells compute how much distance the subjects traveled. All animals, including humans, need to know where they’re located at a certain point in order to compare to their reference frame and navigate. Which way is left, right, up, down etc. How reward anticipation and reward seeking or navigation are connected has escaped scientists for some time.

“Look at any animal’s behavior,” Mehta said, “and at a fundamental level, they learn to both anticipate and seek out certain rewards like food and water. But until now, these two worlds — of reward anticipation and navigation — have remained separate because scientists couldn’t measure both at the same time when subjects are walking.”

Navigation requires the animal to form a spatial map of its environment so it can walk from point to point. An anticipation of a reward requires the animal to learn how to predict when it is going to get a reward and how to consume it. Mehta and colleagues, using their rat virtual environment, have now found a way to correlated the two.

The rat MATRIX

While the rats where navigating their environment in search for the reward (food), visual and auditory cues were played. When both sound and visual was played, the rats used both their legs and tongue to navigate in harmony and easily locate the feed tube. Yum!  This confirmed a long held expectation, that different behaviors are synchronized. When the visual cues were shut off, and only sound was there, the rats legs seemed to be “lost” as the rodents randomly walked about, but their tongue showed a clear map of space, as if the tongue knew where the food was.

“They demonstrated this by licking more in the vicinity of the reward. But their legs showed no sign of where the reward was, as the rats kept walking randomly without stopping near the reward,” he said. “So for the first time, we showed how multisensory stimuli, such as lights and sounds, influence multimodal behavior, such as generating a mental map of space to navigate, and reward anticipation, in different ways. These are some of the most basic behaviors all animals engage in, but they had never been measured together.”

Previously, Mehta said, it was thought that all stimuli would influence all behaviors more or less similarly.

“But to our great surprise, the legs sometimes do not seem to know what the tongue is doing,” he said. “We see this as a fundamental and fascinating new insight about basic behaviors, walking and eating, and lends further insight toward understanding the brain mechanisms of learning and memory, and reward consumption.”
The study results were reported in the journal  PLOS ONE.

Rats have a double view of the world

Rodents are able to move their eyes in different directions, thus always keeping an eye on the the airspace above them, researchers from Max Planck Institute have shown.

rat eye

Using miniaturised high-speed cameras and high-speed behavioural tracking, they found that rats can move their eyes in different directions, both in the horizontal and in the vertical plane; the eyes move individually depending on how the animal is running around and moving its head.

Like most mammals, rats have their eyes on the side of the head, giving them a wide view which is very useful in detecting predators. However, generally speaking, three-dimensional vision requires an overlap of the visual fields of the two eyes; so the visual system needs to fulfill two needs, which are pretty conflicting: on the one hand they need maximum wideness field, and on the other hand, they also need detailed binocular vision.

The research conducted by the Max Planck Institute for Biological Cybernetics has, for the first time, characterized the eye movement of freely moving rats – and their findings came as a total surprise.

“Humans move their eyes in a very stereotypical way for both counteracting head movements and searching around. Both our eyes move together and always follow the same object. In rats, on the other hand, the eyes generally move in opposite directions,” explains Jason Kerr from the Max Planck Institute for Biological Cybernetics.

In their series of behavioral experiments, they also found that the movement of the eyes come as a response to the movement of the head.

“When the head points downward, the eyes move back, away from the tip of the nose. When the rat lifts its head, the eyes look forward: cross-eyed, so to speak. If the animal puts its head on one side, the eye on the lower side moves up and the other eye moves down.” says Jason Kerr.

For us humans, the situation lies quite differently. The direction in which the eyes look must be precisely aligned, otherwise the object isn’t fixated and it all becomes blurry. Any slight deviation, of under a degree, will cause double vision. In rats, the opposing eye movements between left and right eye mean that the line of vision varies by as much as 40 degrees in the horizontal plane and up to 60 degrees in the vertical plane.

Although the observed eye movements prevent the fusion of the two visual fields, the scientists postulate that permanent visibility in the direction of potential airborne attackers dramatically increases the animals’ chances of survival.

Via MPG

Peer reviewed article

Poisoning rats is poisoning birds

Law-makers in Canada and the US are making moves to restrict rat poisons based on blood thinners as studies show that the toxins accumulate in birds of prey and other animals.

Blood thinning and rats

For many people, rats are the worst pets, and they will use all sorts of methods to get rid of them; one method, really common throughout North America is anticoagulant rodenticides (ARs), which work like the human blood-thinning drug warfarin. Warfarin is an anticoagulant that can be used as a poison itself, but it is less likely to accumulate in animals than its successors, which are far more dangerous.

But there was an unexpected effect.

“It seems that every time anybody goes out and gets a bunch of dead birds of prey and looks at their livers, they find surprisingly high incidence of these compounds,” says John Elliott, an ecotoxicologist at Environment Canada in Delta.

Colateral damage

In a study conducted over 130 dead birds, researchers found that “virtually 100%” of the owls and a large proportion of the hawks had residues of at least one second-generation AR in their livers. The discoveries were announced at the 2012 meeting of the North American division of the Society of Environmental Toxicology and Chemistry in Long Beach, California.

“From a regulatory point of view [second-generation ARs] are ‘PBT’,” he says. “Persistent, bioaccumulative and toxic.”

Presumable, the birds eat rats, but this can also happen to smaller birds: insects eat the bait and birds then eat the insects. The good news is that the population was quite responsive to the news, and hopefully, they will avoid using AR as poisons.

“We know consumers can comprehend and respond to warnings about wildlife exposures,” says Fairbrother. A few years ago, she adds, a survey asked consumers whether they knew that rodenticides could affect non-target wildlife. “They had no idea,” she says. But once alerted, their response was, “Now that I know, I’m going to be a lot more careful about how I use them”.

Scientists create brain with 12 seconds memory

The purple round thing you are looking at is actually a microscopic brain derived from rat neurons, just about 50 of them. Developed by researchers from the University of Pittsburg, it only has a memory of 12 seconds, which is about 11 more than what researchers were hoping for.

The brain was created in an attempt to artificially nurture a working brain into existence, thus providing more information about how neural networks function so efficiently and how our brain transmits electrical impulses are transmitted and data is stored. They did this by attaching a layer of protein to a silicon disk and adding braing cells extracted from embrionic rats.

The study was extremely successful, and as if growing and nurturing the tiny, functioning, donut-shaped brain in a petri dish wasn’t enough, they found that when they stimulate the neurons with electricity, the pulse circulates through the brain for a good 12 seconds, which is much more than they expected.

Over 1000 new species discovered near Mekong in the past year

Laotian rock rat

Laotian rock rat

According to a report launched by the World Wildlife Fund (WWF), more than a thousand species were discovered just in the last decade in that particular area. A rat thought extinct for 11 million years and a hot pink, dragon millipede that produces cyanide are just two of the amazing species found there.

If you’re still not convinced how amazing this is, just do the math a bit; 1068 species in the last decade means about two new species found each weak. Also, included on this list world’s largest huntsman spider, with a foot-long leg span and the Annamite Striped Rabbit, which is one of the mammals found there; new species of mammals are found quite rarely.

Despite the fact that most species were discovered in places where you’d expect them to live (such as moist jungles), some were found in the most unusual spots. For example, the Laotian rock rat was found in a local food market by scientists! What’s even more amazing is that this rat was thought to be extinct for more than 11 million years! The Siamese Peninsula pit viper was found slithering in a local restaurant (the hygiene they have there…).

“This report cements the Greater Mekong’s reputation as a biological treasure trove — one of the world’s most important storehouses of rare and exotic species,” said Dekila Chungyalpa, Director of the WWF-US Greater Mekong Program. “Scientists keep peeling back the layers and uncovering more and more wildlife wonders.”