Knowledge Update

London, March 3 (IANS) For the first time, scientists at the University of Cambridge have managed to create an artificial structure from stem cells that resembles a natural mouse embryo.

The findings could pave the way for developing artificial human life in the lab and help researchers understand why more than two out of three human pregnancies fail at the very early stages of embryo development.

Currently, embryos are developed from eggs donated through IVF clinics.

"We are very optimistic that this will allow us to study key events of this critical stage of human development without actually having to work on embryos. Knowing how development normally occurs will allow us to understand why it so often goes wrong," said lead researcher Magdalena Zernicka-Goetz, Professor at University of Cambridge.

For growing the mouse structure in culture, the researchers used two types of stem cells -- the body's 'master cells' -- and a 3D scaffold on which they can grow.

Previous attempts to grow embryo-like structures using only ESCs have had limited success.

This is because early embryo development requires the different types of cell to coordinate closely with each other.

However, in this study published in the journal Science, the researchers described how, using a combination of genetically-modified mouse embryonic stem cells and the extra-embryonic trophoblast stem cells, together with a 3D scaffold, they were able to grow a structure capable of assembling itself and whose development and architecture very closely resembled the natural embryo.

"Both the embryonic and extra-embryonic cells start to talk to each other and become organised into a structure that looks like and behaves like an embryo," Zernicka-Goetz said.

"It has anatomically correct regions that develop in the right place and at the right time," she added.

Comparing their artificial 'embryo' to a normally-developing embryo, the team was able to show that its development followed the same pattern of development. 

The stem cells organise themselves, with ESCs at one end and TSCs at the other. A cavity opens up within each cluster before joining together, eventually to become the large, so-called pro-amniotic cavity in which the embryo will develop, the researchers said. 

While this artificial embryo closely resembles the real thing, it is unlikely that it would develop further into a healthy foetus, the researchers said. 

To do so, it would likely need the third form of stem cell, which would allow the development of the yolk sac, which provides nourishment for the embryo and within which a network of blood vessel develops. 

In addition, the system has not been optimised for the correct development of the placenta, the researchers said.

Melbourne, March 2 (IANS) The brains of obese people could be "wired" to seek out fatty foods, Australian scientists have found.

Researchers from the Bio-Medicine Discovery Institute at Melbourne's Monash University are investigating the messaging system between the brain and the body with hopes of discovering the neurological cause of obesity, Xinhua news agency reported.

"There is no question the brain is the key site regulating appetite and obesity," associate professor Zane Andrews from Monash told Thursday.

"There are a number of genetic mutations that increase the risk of obesity and the majority are located somewhere in the brain."

Andrews said his focus was on brain cells responsible for sensing hunger that also influenced motivation and reward.

He said that early results indicated that the brains of obese people were not sending messages to tell the body that they already have enough energy stored.

Andrews' team has identified that part of the problem could form while the brain pathways are forming during childhood, with children who are rewarded for good behaviour with sweet treats, forming an association between sugar and feeling good.

The team has been able to delete an enzyme in mice that plays an important role in stopping the brain from sending messages that the body is still hungry.

"What we think is the problem in obesity is that those cells are not receiving or sensing the signals to say the person is full so they keep firing, causing people to continue eating," Andrews added.

​New York, March 2 (IANS) Researchers have found a way to activate the immune system's natural cancer-killing T-cells and cause tumours to shrink in mice with colon cancer.

The intervention essentially trains the immune system to recognise and attack the tumour, and to protect against additional tumour formation - a significant issue in colon cancer, said corresponding author Ajay Maker, Associate Professor at University of Illinois College of Medicine in Chicago, US.

In the study, published in the journal Cancer Research, the researchers reported that increasing expression of a chemical cytokine called LIGHT in mice with colon cancer activated the immune system's natural cancer-killing T-cells and caused primary tumours in the liver to shrink.

LIGHT is an immune-stimulating chemical messenger previously found to have low levels of expression in patients with colon cancer metastases.

"For most patients with colon cancer that has spread to the liver, current treatments are palliative and not curative," Maker said.

"And while studies have suggested that immunotherapy may be a promising approach for advanced cancers, the use of such treatments for advanced gastrointestinal metastases have not yet been very successful," Maker said.

This study is exciting because it looks at an immunotherapy intervention for a previously unresponsive gastrointestinal cancer, Maker said.

For the study, the researchers established colon cancer tumors in a mouse model, in which the animals had an intact and unedited immune system. 

Once tumours were sizable, the mice were randomised into two groups - one group had the cytokine LIGHT turned on in the tumours, and the other served as a control group for comparison.

Tumours exposed to LIGHT showed an influx of T-cells that resulted in rapid and sustained diminishment in size, even after expression of the cytokine stopped. 

In cases where the tumour spread to liver, expression of LIGHT similarly provoked a potent immune response that resulted in a significant decrease in tumour burden.

"We demonstrated that delivery of a therapeutic immune-stimulating cytokine caused T-cells to traffic to tumours and to become activated tumor-killing cells," Maker said. 

Johannesburg, March 2 (IANS) African elephants -- the largest land animal -- sleep for just an average of two hours a day and regularly survive for nearly two days without sleep, a study has found.

Previous studies of sleep in captive elephants have shown that they sleep for four to six hours per day. 

However, "in their natural habitat, wild, free-ranging elephants sleep only for two hours per day, the least amount of sleep of any mammal studied to date, but this appears to be related to their large body size," said Paul Manger from the University of Witwatersrand in South Africa. 

For the study, published in the journal PLOS ONE, the team monitored two free-roaming African elephant matriarchs in Chobe National Park in Botswana for 35 days. The elephants were implanted with an actiwatch, in the trunk to track sleep accurately and a collar with a gyroscope to track sleeping position.

The researchers found that the elephants slept an average of two hours a day -- the shortest known sleep time of any land mammal. 

On several days, the elephants were found to survive without sleep for up to 46 hours. 

They travelled long distances of around 30 km during these periods, possibly due to disturbances such as lions or poachers and were found to sleep lying down only every few nights. 

"In addition, it appears that elephants only go into REM (rapid eye movement), or dreaming, sleep every three to four days, which makes elephant sleep unique," Manger added.

Beijing, March 2 (IANS) China will launch a space station core module in 2018 as the first step in completing the country's first space outpost, Xinhua news agency reported.

The core module of the space station, named "Tianhe-1" according to previous reports, will be launched on board a new-generation Long March-5 heavyweight carrier rocket, said Bao Weimin, director with CASC and a member of the National Committee of the Chinese People's Political Consultative Conference (CPPCC).

It will be followed by a series of launches for other components of the space station, including two space labs, which will dock with the core module while in space, in the next four years or so, he said, adding that the space station will be completed around 2022.

Assembly of the core module has already been completed and tests are currently under way, said Bao, who is in Beijing for the annual session of China's top political advisory body.

Earlier reports said the new Chinese space station will initially be much smaller than the current International Space Station (ISS), which weighs 420 tonnes, but could be expanded for future scientific research and international cooperation.

With the ISS set to retire in 2024, the Chinese space station will offer a promising alternative, and China will be the only country with a permanent space station.

Bao said the Chinese outpost will function in orbit for "dozens of years", and that it had been specially designed to be able to handle space debris.

"For the big pieces (of space debris), we could conduct evasive manoeuvres, and for those measuring less than 10 cm in size, we just take the hit," Bao said, adding that all key parts of the space station will be serviceable and replaceable.

He went on to say that the next five years will see some exciting advances in China's space programme.

London, March 1 (IANS) Frogs have the unique ability to see colour even when it is so dark that we are not able to see anything at all, new research has found.

The findings, published in the journal Philosophical Transactions of the Royal Society B, suggest that the night vision of frogs and toads may be superior to that of all other animals. 

"It's amazing that these animals can actually see colour in extreme darkness, down to the absolute threshold of the visual system. These results were unexpected," said one of the study authors Almut Kelber, Professor at Lund University in Sweden.

Most vertebrates, including humans, have two types of visual cells located in the retina, namely cones and rods. 

The cones enable us to see colour, but they usually require a lot of light and, therefore, stop working when it gets dark, in which case the rods take over so that we can at least find our way home, although in black and white.

In toads and frogs, the rods are a bit special. 

It was previously known that toads and frogs are unique in having rods with two different sensitivities. 

This has not been found in other vertebrates, and it is also the reason why researchers have long suspected that frogs and toads might be able to see colour also in low-light conditions.

The new study proves this to be true, and the results exceeded all expectations.

The researchers studied to what extent frogs and toads use their colour vision when searching for a mate or hunting for food. 

The results showed that the animals stop using their colour information fairly early when it comes to finding someone with whom to mate, whereas they continue to take advantage of their colour vision to select food in such low-light conditions that humans lose their ability to see colour.

"We have previously shown moths and geckos are also able to see colour in inferior light conditions compared to humans. However, frogs apparently have a unique ability to see colour in the dark," Kelber said.

New York, March 1 (IANS) Researchers have identified 35 mosquito species, including 26 previously unsuspected ones, that could possibly transmit the deadly Zika virus.

"The biggest take-home message is that these are the species that we need to prioritise," said lead author Michelle Evans from University of Georgia in the US. 

Zika virus is currently known to be transmitted to people primarily through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). 

These are the same mosquitoes that spread dengue and chikungunya viruses, according to US Centers for Disease Control and Prevention.

The researchers said that targetting Zika's potential vectors -- species that can transmit the virus from one host to another -- is an urgent need, given its explosive spread and the devastating health effects associated with it.

The new predictive model, detailed in the journal eLife, could streamline the initial step of pinpointing Zika vectors.

"What we've done is to draw up a list of potential vector candidates based on the associations with viruses that they've had in the past as well as other traits that are specific to that species," study co-author Courtney Murdock, Assistant Professor at University of Georgia, said.

"That allows us to have a predictive framework to effectively get a list of candidate species without having to search blindly," Murdock said.

The researchers developed their model using machine learning, a form of artificial intelligence that is particularly useful for finding patterns in large, complicated data sets. 

Data used in the model consisted of information about the traits of flaviviruses -- the family that includes Zika, yellow fever and dengue -- and all the mosquito species that have ever been associated with them.

​Washington, March 1 (IANS) A trip past the sun may have selectively altered the production of one form of water in a comet known as Lovejoy -- an effect not seen by astronomers before, a new NASA study suggests.

The findings could shed new light on how much comets might have contributed to Earth's water compared to asteroids.

"Comets can be quite active and sometimes quite dynamic, especially when they are in the inner solar system, closer to the sun," said co-author of the study Michael Mumma, Director of NASA's Goddard Center for Astrobiology. 

NASA scientists observed the Oort cloud comet C/2014 Q2, also called Lovejoy, when it passed near Earth in early 2015. 

Through NASA's partnership in the W. M. Keck Observatory on Mauna Kea, Hawaii, the team observed the comet at infrared wavelengths a few days after Lovejoy passed its perihelion - or closest point to the sun.

The team focused on Lovejoy's water, simultaneously measuring the release of H2O along with production of a heavier form of water, HDO. 

Water molecules consist of two hydrogen atoms and one oxygen atom. A hydrogen atom has one proton, but when it also includes a neutron, that heavier hydrogen isotope is called deuterium, or the "D" in HDO. 

From these measurements, the researchers calculated the D-to-H ratio -- a chemical fingerprint that provides clues about exactly where comets (or asteroids) formed within the cloud of material that surrounded the young sun in the early days of the solar system.

Researchers also use the D-to-H value to try to understand how much of Earth's water may have come from comets versus asteroids.

The scientists compared their findings from the Keck observations with another team's observations made before the comet reached perihelion, using both space- and ground-based telescopes, and found an unexpected difference.

After perihelion, the output of HDO was two to three times higher, while the output of H2O remained essentially constant, showed the findings published online in the Astrophysical Journal Letters.

This meant that the D-to-H ratio was two to three times higher than the values reported earlier.

"If the D-to-H value changes with time, it would be misleading to assume that comets contributed only a small fraction of Earth's water compared to asteroids," lead author of the study Lucas Paganini, a researcher with the Goddard Center for Astrobiology, said.

New York, Feb 28 (IANS) Exoplanets with hydrogen pouring from volcanic sources may have a warmer surface and provide a better target for scientists to find signs of life outside our home planet, says a study.

"On frozen planets, any potential life would be buried under layers of ice, which would make it really hard to spot with telescopes," said lead author Ramses Ramirez from Cornell University in the US.

"But if the surface is warm enough -- thanks to volcanic hydrogen and atmospheric warming -- you could have life on the surface, generating a slew of detectable signatures," Ramirez said.

Combining the greenhouse warming effect from hydrogen, water and carbon dioxide on planets sprinkled throughout the cosmos, distant stars could expand their habitable zones by 30 to 60 per cent, according to this new research published in the Astrophysical Journal Letters.

"Where we thought you would only find icy wastelands, planets can be nice and warm - as long as volcanoes are in view," Lisa Kaltenegger, Professor at Cornell University, said. 

The idea that hydrogen can warm a planet is not new, but an Earth-like planet cannot hold onto its hydrogen for more than a few million years. Volcanoes change the concept. 

"You get a nice big warming effect from volcanic hydrogen, which is sustainable as long as the volcanoes are intense enough," said Ramirez, who suggested the possibility that these planets may sustain detectable life on their surface.

A very light gas, hydrogen also "puffs up" planetary atmospheres, which will likely help scientists detect signs of life. 

"Adding hydrogen to the air of an exoplanet is a good thing if you're an astronomer trying to observe potential life from a telescope or a space mission. It increases your signal, making it easier to spot the makeup of the atmosphere as compared to planets without hydrogen," Ramirez said.

In our solar system, the habitable zone extends to 1.67 times the Earth-sun distance, just beyond the orbit of Mars. 

With volcanically sourced hydrogen on planets, this could extend the solar system's habitable zone reach to 2.4 times the Earth-sun distance -- about where the asteroid belt is located between Mars and Jupiter. 

This research places a lot of planets that scientists previously thought to be too cold to support detectable life back into play.

"We just increased the width of the habitable zone by about half, adding a lot more planets to our 'search here' target list," Ramirez said.

​London, Feb 28 (IANS) If you are using a pacemaker to regulate your heartbeat, be careful about the proximity to your body of everyday household appliances and electrical tools as these may affect the functioning of the device, warns new research.

A pacemaker is a small device that is placed in the chest or abdomen to help control abnormal heart rhythms. This device uses low-energy electrical pulses to prompt the heart to beat at a normal rate and is used to treat problems relating to the rate or rhythm of the heartbeat.

The findings showed that pacemakers are susceptible to electric and magnetic fields (EMF) generated from powerlines, household appliances, electrical tools and entertainment electronics, in particular when programmed to maximum sensitivity or so-called unipolar sensing mode. 

This EMF interference, depending on factors such as the settings of the implant or strength of the field source with pacemakers, can result in bradycardia, or a slow heart rate. 

"Electromagnetic interferences with pacemakers in everyday life can cause harmful interferences," said Andreas Napp, cardiologist at RWTH Aachen University Hospital in Germany.

In many cases, holding the appliance, tool or other EMF source at a forearm's length distance -- greater than 12 inches -- limits the risk of electromagnetic interference. 

Thus, "in occupational environments, such as the manufacturing industry, an individual risk assessment for workers with a pacemaker is required due to the presence of a strong EMF," Napp added, in the paper appearing in the journal Circulation.

However, using dedicated device programming can effectively measure to reduce the individual risk of interference. For example, doctors can reprogramme pacemakers to a lower sensitivity to reduce EMF susceptibility, Napp said.

For the study, the team tested under different conditions the impacts of EMF exposure on 119 patients with pacemakers.