Fruitflies evolve number sense

  • Venue: Nature Magazine

US and Canadian researchers have evolved a population of fruitflies that can count. The result, presented on 9 July at the First Joint Congress on Evolutionary Biology in Ottawa, Canada, supports the notion that the neural mechanisms underlying basic arithmetic skills first emerged hundreds of millions of years ago. It could also eventually offer a key to understanding why some people have problems with numbers.

Few doubt that our closest animal relatives have some capacity to count. A variety of clever studies have also revealed the numerical skills of more distant species, including salamanders, fish and bees. But until now, no one has ever tried to genetically enhance an animal’s counting ability.

To tackle the challenge, evolutionary geneticists Tristan Long, of Wilfrid Laurier University in Waterloo, Canada, and William Rice, of the University of California, Santa Barbara, teamed up to try to create a race of numerically savvy insects. During a 20-minute training period, flies were exposed to either two, three or four flashes of light — two and four flashes coincided with a vigorous shake administered by placing a electric toothbrush next to the box containing the flies. After a brief rest, the flies were returned to box and shown the light flashes. Despite a dislike for being shaken, most of the flies were not able to learn to associate the negative stimulus with the number of flashes. But 40 generations later, they could.

The researchers caution that the work is preliminary and that they do yet know what genetic changes are behind the insects’ evolved number sense.

“The obvious next step is to see how [the flies’] neuro-architecture has changed,” explains Long. He then hopes to look for genetic differences between control and experimentally selected flies to pin down the genes responsible for their enhanced counting ability.

Neuroscientists have long speculated that human mathematical ability is built on an innate foundation that predates language and complex reasoning. Dyscalculia, a poorly understood disorder that affects a person’s ability to learn and perform basic arithmetic operations, may in some cases be related to an impairment of this innate foundation. If so, says Long, fruitflies could help to uncover genetic links to the disorder.

“This project was really about getting people interested in using fruitflies as a model system for understanding numerical competence and its evolution,” he adds.

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Neighbouring cells help cancers dodge drugs

  • Venue: Nature Magazine

Cancers can resist destruction by drugs with the help of proteins recruited from surrounding tissues, find two studies published by Naturetoday. The presence of these cancer-assisting proteins in the stromal tissue that surrounds solid tumours could help to explain why targeted drug therapies rapidly lose their potency.

Targeted cancer therapies are a class of drugs tailored to a cancer’s genetic make-up. They work by identifying mutations that accelerate the growth of cancer cells and selectively blocking copies of the mutated proteins. Although such treatments avoid the side effects associated with conventional chemotherapy, their effectiveness tends to be short-lived. For example, patients treated with the recently approved drug vemurafenib initially show dramatic recovery from advanced melanoma, but in most cases the cancer returns within a few months.

Many forms of cancer are rising in prevalence: for example, in the United States, the incidence of invasive cutaneous melanoma — the deadliest form of skin cancer — increased by 50% in Caucasian women under 39 between 1980 and 2004. So there is a pressing need to work out how to extend the effects of targeted drug therapies. But, until now, researchers have focused on finding the mechanism of drug resistance within the cancerous cells themselves.

Two teams, led by Jeff Settleman of Genentech in South San Francisco, California, and Todd Golub at the Broad Institute in Cambridge, Massachusetts, expanded this search into tumours’ surrounding cellular environment.

Settleman’s team tested 41 human cancer cell lines, ranging from breast to lung to skin cancers. The researchers found that 37 of these became desensitized to a handful of targeted drugs when in the presence of proteins that are usually found in the cancer’s stroma, the supportive tissue that surrounds tumours. In the absence of these proteins, the drugs worked well1. By growing cancer cells along with cells typically found in a tumour’s immediate vicinity, Golub and his colleagues showed that these neighbouring cells are the likely source of the tumour-aiding proteins2.

Protein culprit

One of the most startling results of the teams’ experiments was the discovery that a protein called hepatocyte growth factor (HGF) boosts melanoma’s resistance to treatment with vemurafenib. Intrigued by this result, both teams looked at blood samples from people who had undergone treatment with vemurafenib, and found the higher a patient’s HGF levels, the less likely they were to remain in remission.

Martin McMahon, a cancer biologist at the University of California, San Francisco, who was not affiliated with either study, explains that the results have immediate implications for the design of clinical trials, which he says could combine targeted drug therapy with drugs capable of knocking down the production of proteins such as HGF.

“These papers show that the influence of the cell’s microenvironment is important not only for melanoma, but also for pancreatic, lung and breast cancer,” McMahon says, adding that they are “very exciting, because they expand the focus of where we should be looking for the mechanisms of drug resistance”.

:: Read original here ::

Permafrost, altruism, and whale dialects

  • Venue: BBC

This week in Science in Action we talked to Ted Schuur, University of Florida, about the impacts of methane-producing bacteria munching their way through thawing poleward soils, Craig Baxter, a UK-playwright, about his award-winning play ‘The Alturists’, and Ian Boyd, University of St Andrews, about an open science project to decode whale song.

You can listen to the programme here or download it here.

Science in Action is hosted by Jon Stewart, produced by me and Ania Lichtarowicz, and is a BBC World Service programme that pulls together the science issues of the week and delivers breaking science news.

Resistant bed-bugs ‘from tropics’

  • Venue: BBC

New results suggest that insecticide use in the tropics is to blame for the re-emergence of bed-bug infestations.

Exposure to treated bed nets and linens meant that populations of bed-bugs had become resistant to the chemicals used to kill them, researchers said.

The findings could help convince pest controllers to find alternative remedies to deal with the problem.

The results were presented at the American Society of Tropical Medicine and Hygiene’s 60th annual meeting.

Since almost vanishing from homes in industrialised countries in the 1950s, populations of the common bed-bug have become re-established in these regions over the past decade or so.

These mostly nocturnal feeders are difficult to control, not only because they are adept at avoiding detection by crawling into creases of soft furnishing but also because they have developed a resistance to many of the chemicals that have been used to kill them.

Findings presented at the gathering in Philadelphia showed that 90% of 66 populations sampled from 21 US states were resistant to a group of insecticides, known as pyrethroids, commonly used to kill unwanted bugs and flies.

Bed-bugs in furniture (Image: Richard Naylor/University of Sheffield)
Female bed-bugs, hidden in furniture creases, can each lay up to 300 eggs

 

One of the co-authors – evolutionary biologist Warren Booth, from North Caroline State University in Raleigh – explained that the genetic evidence he and his colleagues had collected showed that the bed-bugs infecting households in the US and Canada in the last decade were not domestic bed bugs, but imports.

“If bed-bugs emerged from local refugia, such as poultry farms, you would expect the bed-bugs to be genetically very similar to each other,” explained entomologist and co-author Coby Schal, also from North Carolina State University. “This isn’t what we found.”

In samples collected from across the eastern US, the team discovered populations of bed-bugs that were genetically very diverse.

This suggested that the bugs originated from elsewhere, and relatively recently because the different populations had not had time to interbreed, Dr Schal explained.

He suggested that the source for the new outbreaks was warmer climes, where the creatures would have probably developed a resistance to chemicals.

“The obvious answer is the tropics, where they have used treated bed nets [and] high levels of insecticides on clothing and bedding to protect the military,” Dr Booth told BBC News.

He explained that although bed-bugs were essentially eradicated from industrialised countries in the 1950s, they continued to thrive in Africa and Asia.

“Its very likely that it is from one of these areas where insecticide resistance evolved,” he said.

‘Home-grown’

However, UK-based pest management specialist Clive Boase questioned that hypothesis.

He said bed nets, to protect against mosquito-transmitted malaria and dengue, were only used in parts of Africa that were hot, where the tropical bed-bug (Cimex hemipterus) was found.

But, he added, it was not the tropical bed-bug that was the problem in the US and UK; instead it was their temperate cousin, Cimex lectularius.

Dr Boase explained that comprehensive records showed that infestations of bed-bugs in Europe were less pervasive in the 1970s and 80s, but they were still present.

By continually exposing these populations to insecticides, which came on the market in the late 1970s, these creatures likely developed resistance, he said.

“We don’t have to invoke stories of disease control programmes in Africa; all the evidence here in the UK is that our problem is home-grown.”

Dr Boase wondered that if the US had similar long-term records whether the researchers would have reached a different conclusion.

Evolutionary biologist Richard Naylor from the University of Sheffield agreed: “I am kind of surprised by [their interpretation].

“It doesn’t seem that difficult to develop resistance or lose it; in lab cultures, if you stop exposing [bed-bugs] to pyrethroids it drops out of lab populations very quickly,” he said.

Mr Naylor asked that if the US bed bugs had been exposed to the chemicals elsewhere in the past, “why would they still be resistant?”

:: Read Original here ::

Vaccine developed against Ebola

  • Venue: BBC

Scientists have developed a vaccine that protects mice against a deadly form of the Ebola virus.

First identified in 1976, Ebola fever kills a majority of the people it infects.

The researchers say that this is the first Ebola vaccine to remain viable long-term and can therefore be successfully stockpiled.

The results are reported in the journal Proceedings of National Academy of Sciences.

Ebola is transmitted via bodily fluids, and can become airborne. Sufferers experience nausea, vomiting, internal bleeding and organ failure before they die.

Although few people contract Ebola each year, its effects are so swift and devastating that it is often feared that it could be used against humans in an act of terroism.

All previously developed vaccines have relied on injecting intact, but crippled, viral particles into the body.

Long-term storage tends to damage the virus, paralysing the vaccine’s effectiveness.

The new vaccine contains a synthetic viral protein, which prompts the immune system to better recognise the Ebola virus, and is much more stable when stored long-term.

The vaccine protects 80% of the mice injected with the deadly strain, and survives being “dried down and frozen,” said biotechnologist Charles Arntzen from Arizona State University who was involved in its development.

He said the next step is to try the vaccine on a strain of Ebola that is closer to the one that infects humans.

:: Read original here ::

Names proposed for new elements

  • Venue: BBC

Scientists have put forward their suggested names for the newest additions to the Periodic Table.

If the names are accepted, element 114 will become Flerovium (Fl) in honour of the physicist Georgiy Flerov.

While element 116 will become Livermorium (Lv), after the Californian laboratory where it was discovered.

The table’s governing body will officially endorse the names in five month’s time, 10 years after the elements were discovered.

The newest elements were among a handful of elements put forward for inclusion in the table in recent years.

They were accredited in June this year after a three year review by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP).

The other putative heavy elements, 113, 115, and 118, are still under review.

Scientists at Lawrence Livermore National Laboratory (LLNL), in collaboration with a team at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia, discovered the newest additions to the periodic table by smashing calcium ions into the element curium to create element 116, which quickly decays to element 114.

The teams also created element 114 separately by replacing curium with a plutonium target.

IUPAC will officially accept the proposed names after giving the public time to comment on the discoverers’ choice.

:: Read original here ::

Second mission to scale deep mountains announced

  • Venue: BBC

Scientists are set to begin a six-week mission to explore the Indian Ocean’s underwater mountains.

Aboard the UK research vessel the RRS James Cook, the team will study animals thousands of metres below the surface.

This year a report in the journal Marine Policy found that deep sea trawling is one of the most damaging forms of fishing.

The expedition will help scientists to better understand the threats to this environment.

The mission, led by the International Union for Conservation of Nature (IUCN), is the second to visit the seamounts along the South-West Indian Ocean Ridge; the first set out in November 2009.

Seamounts are underwater mountains which rise to at least 1,000 metres above the sea floor.

Seamount communities

“Because of their interactions with underwater currents, the biodiversity that develops around them is remarkably rich,” explained Aurelie Spadone, IUCN’s marine programme officer and a member of the team.

“They attract a great diversity of species and act as a type of ‘bed and breakfast’ for deep-sea predators such as sharks, which often feed on seamount communities,” she added.

The catch of deep-sea species has increased seven-fold since the mid-1960s, as stocks of shallower waters plummet and the fishing industry took to exploiting deeper waters.

Industrial fishing at depth, which generally relies on trawling the ocean’s bottom with huge weighted nets, has a huge impact on seafloor ecosystems, say researchers.

Carl Gustaf Lundin, director of IUCN’s Global Marine and Polar Programme explained that very little was known about the species associated with seamounts.

“Many of them grow and reproduce slowly, which makes them particularly vulnerable to overexploitation,” he said.

“Deep-sea bottom fisheries, including bottom trawling, can damage seamount habitats and negatively impact fish stocks. It can also irreversibly damage cold water corals, sponges and other animals.”

Alex Rogers of the University of Oxford and chief scientist on board RRS James Cook said: “We’re hoping that this expedition will help us better understand this unique marine life and assess the threats it faces.

:: Read original here ::

Alien rats take on prey’s role

Invasive rats are compensating for the loss of native pollinators in New Zealand, scientists report.

The rats, which are responsible for devastating the native pollinator populations, are attracted to the flowers for their nectar.

The results could mean that the decline of pollinating animals worldwide does not spell the end for all native plants.

The results are published in a Royal Society journal.

Almost 90% of the world’s flowering plants are pollinated by animals.

Insect pollination alone is estimated to be worth £141bn ($224bn) each year, and according to a report from the UN Food and Agriculture Organization (FAO) bees pollinate over two-thirds of the world’s crops.

So the decline of the world’s pollinating animals has unsurprisingly sparked concerns about lower yields and serious long-term food shortages among farmers and governments.

Conservationists also predict the loss of many animal-pollinated plants.

“New Zealand offers a really interesting and rare opportunity to look at what the consequences of species extinction [are] for… pollination,” explained conservation biologist David Wilcove from Princeton University, US.

“We have this situation where almost all of the native vertebrates in New Zealand – birds, bats and reptiles – have disappeared from the North island… largely due to predation by rats,” he added.

But a small patch of pristine New Zealand woodland still exists, affording the researchers the opportunity to investigate the impact of losing key pollinating species on endemic plant species.

Dr Wilcove, and his then Princeton colleague David Pattemore, set out to study three plants: the red-flowered Metrosideros and Knightia, and the purple-flowered Veronica.

What the duo didn’t expect to see was that on the mainland, where the plants were no longer visited by traditional pollinating species, rats, and a recently colonising bird, were doing the job instead.

And for two of the three plant species, the invasive species were doing a comparable job to the native pollinators.

“I was quite startled by it,” said Dr Wilcove.

He explains that, in general, this type of compensation is more likely to happen for flowering plants that are pollinated by many different animals.

But for plants that rely on a very specialist pollinator, the loss of its sole pollinating animal still spells doom for the species.

Most crops, Dr Wilcove suspects, are pollinated by multiple species, and so there might be room for one pollinator to be replaced by another.

So for crop species, these findings should be encouraging, he suggested.

“I think this result should at least force people to think more carefully about what possible beneficial role the non-native [species] are having… and perhaps develop a slightly different control strategy,” he added.

:: Read original here ::

Jawbones are ‘shaped by diet’, a study finds

  • Venue: BBC

Diet has shaped human jaw bones; a result that could help explain why many people suffer with overcrowded teeth.

The study has shown that jaws grew shorter and broader as humans took on a more pastoral lifestyle.

Before this, developing mandibles were probably strengthened to give hunter-gatherers greater bite force.

The results were published in the Proceedings of the National Academy of Sciences.

“This is a fascinating study which challenges the common perception that there has been little recent change in the morphology of humans,” said anthropologist Jay Stock from the University of Cambridge.

Many scientists have suggested that the range of skull shapes that exist within our species is the result of exposure to different climates, while others have argued that chance played more of a role in creating the diversity we see in people’s profiles.

The new data, collected from over 300 skulls, across 11 populations, shows that jaws shortened and widened as humans moved from hunting and gathering to a more sedentary way of life.

The link between jaw morphology and diet held true irrespective of where people came from in the world, explained anthropologist Noreen von Cramon-Taubadel from the University of Kent.

Concurrently crooked

It would be tempting to conclude that this is evidence for concurrent evolutionary change – where jaw bones have evolve to be shorter and broader multiple, independent times, she told BBC News.

But the sole author of the paper suggested that the changes in human skulls are more likely driven by the decreasing bite forces required to chew the processed foods eaten once humans switch to growing different types of cereals, milking and herding animals about 10,000 years ago.

“As you are growing up… the amount that you are chewing, and the pressure that your chewing muscles and bone [are] under, will affect the way that the lower jaw is growing,” explained Dr von Cramon-Taubadel.

She thinks that the shorter jaws of farmers meant that they have less space for their teeth relative to hunter-gatherers, whose jaws are longer.

Teeth-pulling tale

“I have had four of my pre-molars pulled and that is the only reason that my teeth fit in my mouth,” said Dr von Cramon-Taubadel.

Ever since that time, she has wondered why so many people suffer with teeth-crowding.

“I think that’s the reason why this result resonates with people,” she said.

Dr Stock added: “[The finding] is particularly important in that it demonstrates that variation that we find in the modern human skeletal system is not solely driven by population history and genetics.”

These results fit with previous evidence of both a reduction in tooth and body size as humans moved to a more pastoral way of life.

It also helps explain why studies of captive primates have shown that animals tend to have more problems with teeth misalignment than wild individuals.

Further evidence comes from experimental studies that show that hyraxes – rotund, short-tailed rabbit-like creatures – have smaller jaws when fed on soft food compared to those fed on their normal diet.

:: Read original here ::