Freshwater Fish Populations See Rapid Decline
Sept. 1, 2009 -- Just a few hundred years ago, the world's rivers and lakes teemed with gigantic fish. Freshwater fish were so plentiful that they were used to feed farm animals and fishermen found it hard not to make a catch, according to a new review of historical accounts.
Oceans get most of the attention when it comes to aquatic conservation. But the new study suggests that freshwater species have declined precipitously, too, and that conservation efforts aren't aiming big enough when it comes to rivers, lakes and streams.
"When you look at these accounts, it is pretty amazing how abundant and especially how large these fish species were that people wrote about," said Kirk Winemiller, a fisheries ecologist at Texas A&M University in College Station, Texas. "We have a very inaccurate view of that history."
Along with colleague Paul Humphries in Australia, Winemiller looked back through newspaper articles, diaries and other historical records dating back to the arrival of European settlers in the mid-1800s in Australia and the early-1600s in North America.
The researchers didn't crunch numbers or analyze data. Rather, they aimed to get a general picture of what lakes and rivers around the world used to look like.
Bodies of freshwater, they found, have changed dramatically over the years.In 1620, Captain John Smith wrote that his crew of pilgrims in New England had caught enough sturgeon, salmon, eels and other species in one night to fill 12 hogsheads. These containers measured four feet by 2.5 feet and could hold 1,000 pounds of tobacco each.
In the 1700s, travelers described huge stocks of pike, walleye, catfish and other fish in the Ohio River. In 1804, Meriwether Lewis and William Clark mentioned dense and spectacular salmon runs in the Columbia River in the Pacific Northwest.
In Australia, likewise, explorers caught 200-pound cod and other huge fish on demand, even in the Murray-Darling Basin, where heavy agriculture has decimated many species and big fish are now non-existent. In some places, freshwater fish were so plentiful that they were used as pig feed.
The demise of most of the world's grand freshwater fish, Winemiller said, was a direct result of overfishing. Today, huge lake and river fish live only in the few places in the world that are free of human influence, such as the Guiana Shield in South America.
"People rarely appreciate the major impact that even a fairly moderate amount of fishing has on certain freshwater stocks," said Winemiller, who added that the loss of big predator species reverberates throughout the ecosystem. "The impact started very long ago."
In the last decade or two, scientists have focused mostly on protecting and restoring species in the oceans, where animals were also once much larger and much more numerous than they are today. The new study, with its historical perspective on what's possible in bodies of freshwater, suggests that rivers and lakes may benefit from more aggressive protective measures, like the reserves that are becoming more common in marine areas.
The study also points to freshwater conservation as a global issue, said Zeb Hogan, a conservation biologist at the University of Nevada, Reno, even though people often think of rivers and lakes as local resources.
White sturgeons in the Fraser River in British Columbia, for example, are often considered the healthiest population of that fish anywhere in the world. Yet, the river used to hold 10 times as many sturgeons.
"I feel like we're sort of behind the game in terms of global freshwaterbiodiversity conservation," Hogan said. "Until we start acknowledging that the abundance of large freshwater fish has declined, we're going to continue to set restoration goals too low, and we're going to continue having extinctions."
Oceans Could Absorb Much More CO2
Sept. 1, 2009 -- Earth's oceans are vast reservoirs of carbon dioxide (CO2) with the potential to control the pace of global warming.
It all hinges on the fate of marine "snow" -- a constant sprinkle of carbon-rich bits that flutter down from the sea surface to the cold depths below. And according to a new study, the flurries could suck much more of the greenhouse gas out of the atmosphere than previously thought.
Each year, phytoplankton floating in the seas' big blue expanse drink in 10 billion tons of carbon from the air (humans emit about 8 billion tons). Their shells and excretions rain down from the surface, providing a feast for creatures that recycle up to 90 percent of the Carbon back in to the Water as CO2. Only a light dusting lands on the ocean floor.
But small changes in this carbon system have big implications for climate.
Today, most of the recycling happens in the first 210 meters (689 feet) below the ocean surface. According to a new study published in the journal Nature Geoscience, if that depth sank by just 24 meters, it could remove up to 27 parts per million more of CO2 from the atmosphere.
This is because the deeper the snow falls into the ocean without being eaten, the more carbon-rich snow reaches the ocean floor. Once it is eaten, it becomes dissolved CO2, and it's just a matter of a short time (months to years instead of tens of thousands of years for the snow) before it makes its way back into the atmosphere.
"People are going to be scratching their heads and saying, 'Wow, that's really sensitive,'" Ken Buesseler of the Woods Hole Oceanographic Institute in Massachusetts, who was not involved in the study said. "That's not very big -- natural variability of that depth is several hundred meters."
By comparison, scientists estimate the ocean helped usher in the most recent ice age tens of thousands of years ago when it drained between 30 and 77 parts per million of CO2 from the air.
That won't happen any time soon. Humans have added well over 100 parts per million of CO2 as well as other greenhouse gases to the atmosphere in the last two centuries, and many scientists predict that ocean warming will raise the depth at which most carbon cycles back into the water. If that happens, the seas will hasten global warming as they spew CO2 back out into the air.
"On the other hand, a decrease in oxygen concentration in the ocean, which might be caused by enhanced stratification of the global ocean, might slowdown bacterial metabolic rates," and increase the amount of snow that reaches the deep ocean, Eun Young Kwon of Princeton University, the study's lead author said.
"The answer is I don't know. This is the major gap to be filled in our research community in the future."
Infrared Eye to Help Search for Asteroids
Aug. 31, 2009 -- NASA is preparing to launch an infrared telescope named WISE that could indeed live up to its name. Among its targets: dark asteroids that have slipped beneath radar of an ongoing project to map objects larger than 1 kilometer that orbit near Earth.
Hunting asteroids wasn't in the original plan for the Wide-field Infrared Survey Explorer, known by the acronym WISE, which arrived at Vandenberg Air Force Base in California this month for launch preparations.
"I was recruited when the team realized they would be seeing a lot of asteroids, some of which may be new," said University of Texas astronomer Robert McMillan who leads Spacewatch, an asteroid-survey project.
"They wanted someone who had connections with the ground-based telescope community who'd be able to do follow-ups," McMillan told Discovery News.
With a quartet of infrared sensors and a wide view, WISE is designed to survey the whole sky in Infrared Light. It's not the first telescope to do so, but scientists expect WISE's observations will be 500 times sharper than a survey conducted in 1980s by IRAS, the Infrared Astronomical Satellite, said astronomer Martin Cohen, with the University of California at Berkeley.
The data will be complied into an all-sky infrared atlas, a tome that is expected to include about 300 million objects, including about 100,000 asteroids.
Many of the asteroids seen by WISE will be known objects. Scientists hope to use the new observations to nail down details, such as an asteroid's diameter and surface reflectivity.
"With ground-based scopes, it's just a point source. You can't tell size directly," McMillan said. "A big object that is dark and a small object that is bright are going to look like they have the same brightness."
The solar system contains several million asteroids, most of which reside in the Main Asteroid Belt between Mars and Jupiter. About 7,000 asteroids have been identified that cross or come close to Earth's orbit.
WISE will be able to spot asteroids emitting heat due to direct exposure from the sun, as opposed to visible-light searches that find asteroids that are reflecting sunlight.
"Those are two different physical effects," said McMillan. "An asteroid that has very dark color in invisible light is going to get heated up more, just like a black car in a parking lot is going to get heated up more than a white car."
Scientists hope to get enough positioning information to follow up targets with ground-based observations. McMillan expects that WISE will discover a few hundred new asteroids. The information will be folded into ongoing surveys to map asteroids that could impact Earth and cause widespread damage.
Other WISE targets include brown dwarfs, which are Jupiter-sized stars that never got their nuclear fusion engines running and ultra-luminous galaxies, which pump out the equivalent of about 1,000 sun-sized stars every year.
These galaxies are among the most luminous objects in universe, said WISE lead scientist Edward Wright.
WISE should be able to spot these galaxies back to when the universe was about 2 billion years old.
The telescope is scheduled to be launched on Dec. 7. The $300 million mission covers a month-long checkout and six months of science operations. The spacecraft is designed to last two years.
Iron Age Butter Discovered in Ireland
Aug. 31, 2009 -- Irish workers have discovered one of the earliest examples of packaged and preserved food.
An oak barrel dating back to about 3,000 years ago has been found filled with exceptionally well-preserved butter.
Cut out of a trunk, the three-foot-long, almost one-foot-wide butter barrel weighs 35 kilograms (77 pounds) and comes complete with a lid.
The butter was found by peat workers John Fitzharris and Martin Lane, who spotted it as they harrowed the Gilltown bog in County Kildare,Ireland.
"We knelt down and felt something hard and started to dig it out with out bare hands. We could smell it, and it was attracting crows," Fitzharris told local reporters.
Now housed at the conservation department of the National Museum of Ireland, the barrel and its buttery contents are being cleaned and analyzed.
The aim is to "conserve both the vessel and the butter. It is hoped that through further tests the species of the wood will be identified and the vessel dated through radiocarbon dating," the museum said in a statement.
The newly found barrel is typologically similar to a number of vessels already in the museum's collection, which have been dated to the Iron Age 500 B.C. - 500 A.D.
Split along the middle due to the expansion of butter over time, the barrel features tool marks from a knife, chisel, adze or axe.
Inside, the butter has turned white and is now adipocere, a kind of wax.
"It's rare to find such a well preserved butter barrel, with the lid intact and attached. It is an invaluable addition to the national collection," Padraig Clancy, assistant keeper at the National Museum of Ireland, told Discovery News.
According to Clancy, it is likely that the butter was put in the bog for practical reasons, rather than ritual. Probably, it was the stored harvest of an Iron Age community, who used the bog as a primitive kind of fridge.
Indeed, burying food -- and many other things -- in peat bogs wasn't an unusual practice.
Some 270 packages of butter have been retrieved from bogs, along with exceptionally well-preserved wooden objects, swords and ornaments.
The bogs' unique chemistry is what allows these artifacts to endure. The peat-building Sphagnum moss grows over anything tipped into the bog, embedding the buried material in cold, acid- and oxygen-free conditions that immobilize bacteria, preventing decomposition.
This hygienic seal has worked perfectly for the so-called "bog butters," allowing researchers to identify the content of the waxy material. In 2004, analysis by Richard Evershed and his team at the University of Bristol, United Kingdom, confirmed that fat parcels found in bogs were made of butter or lard.
However, some mystery remains. It is not known whether the butter was just buried in the peat with the simple aim of preserving it, or whether the bog served for some primitive food processing, basically to make the butter more tasty.
According to the museum experts, the newly found bog butter has been tasted long before, but there are no plans to do that again.
"It's a national treasure. You can't be going hacking bits of it off for your toast," they told reporters.
Mysterious Weather Pulses Help Predict Hurricanes
Aug. 31, 2009 -- Every month or so, a wave of mysterious weather pops up over the Indian Ocean and begins marching eastward through the tropics.
Scientists are unsure what causes it, but a new study has shown that tracking these pulses -- known as the Madden Julian Oscillation -- could allow weather forecasters to predict hurricane and tropical storm formation up to three weeks ahead of time.
Forecasters know enough about the conditions that produce these vicious storms to make annual guesses about how active each hurricane season might be, and to forecast their behavior about five days into the future once they form.
But in between is a vast chasm of uncertainty.
Frederic Vitart of the European Center for Medium-Range Weather Forecasts in the United Kingdom is beginning to bridge that gap, by shedding light on the way the Oscillation influences tropical storm formation, intensity and movement.
Alternating between a vast province of moist, stormy air or an unusually dry patch, the Oscillation slowly blows through the tropics, often circling the globe several times. In a computer simulation of the last 20 years of hurricane seasons, Vitart showed it could increase or decrease risk that a storm would make landfall by as much as 50 percent.
The results were published earlier this month in the journal Geophysical Research Letters.
"The Madden Julian Oscillation creates large-scale conditions which are known to favor tropical storm genesis," he said, bringing with it increased moisture and weakening wind shear.
Vitart's model reliably predicts storm formation out to about 20 days. But the Oscillation is a diffuse, widespread weather pattern; using it to forecast hurricanes can dramatically improve forecasts, but it does not turn weather models into crystal balls.
Even armed with knowledge of the Oscillation's influence on Hurricane Katrina, for instance, no one could have foreseen the storm's devastating strike on New Orleans.
"We may not be able to predict the strike of a storm at a given time and given location, but we can predict if the probability of a tropical storm strike will increase or decrease in the next few weeks over a large area," Vitart said.
"I think that the forecasting that would arise from the Madden Julian Oscillation would be different in nature from the three- and five-day operational track forecasts that currently come out of the National Hurricane Center, which predict the track (and cone of uncertainty) of a storm that already exists," Gabriel Vecchi of the National Oceanic and Atmospheric Administration in Princeton, New Jersey said in an email to Discovery News.
"The Madden Julian Oscillation would help us to predict the genesis of a storm that doesn't exist yet, and the likely character of its track, landfall, etc."
Vitart added that he is working on developing a way to use this type of forecasting to construct maps that display advanced warning of increased risk of hurricane strikes for a given stretch of islands or coastline.
Robofish Takes To Water
Aug. 28, 2009 -- A school of small, robotic fish has been developed by MIT scientists. Made with a only handful of parts and a blend of polymers, the fish wiggle their way through water like trout and tuna.
These new robofish could be equipped with sensors to monitor oilspillsor other environmental contaminants.
"The interesting aspect of this research is that we are the first group to tailor different polymers in different parts of the body with different dampening and stiffness properties," said Kamal Youcef-Toumi, a scientist at MIT who, along with Pablo Vildivia Y Alvarado, is developing the robofish.
"We are also looking at using the natural motion and behavior of the fish and replicating those motions," said Youcef-Toumi.
The 18 new robofish have advanced significantly since the original Robotuna was created at MIT in 1994. Robotuna had more than 2,000 parts, including six motors, encased in its four-foot body.
These new models have less than 10 parts, including one motor, and are between five and eight inches long.
Youcef-Youmi and Vildivia Y Alvarado began developing the five-inch robofish four years ago, modeling their movements on freshwater fish like trout and bass. These small fish swim mostly by moving the tail, while the rest of the body remains motionless.
The most recent robofish are eight inches long and modeled to swim like salt water tuna. Instead of wiggling just the tail, tuna swim by moving their body as well, undulating back and forth to swim faster than trout or bass.
Whatever the length or swimming method, all the robofish are encased in a special blend of molded polymers. The body of the fish is one single piece of material, but each section of the body has a different stiffness, allowing the motion of one actuator to move through the robofish's entire body, propelling it forward.
One actuator allows for limited movement, basically forward and side to side. To move up and down and more complex movements will require two additional actuators be installed.
The unibody construction also protects the electrical and mechanical parts inside the robot; some robofish have been swimming for more than four years.
The robofish might mimic real fish, but they can't compete in terms of speed. The maximum speed of the robofish is less than one body length per second. Some fish can swim up to 10 body lengths per second.
Movement requires energy, and the robofish currently get their power from an attached power cable. Batteries could be installed to power robofish remotely in streams and bays, where they could be equipped with sensors to detect pollution or cameras to study animals that would be disturbed by the noise caused by propellers.
Fish aren't the only underwater creatures the MIT robotics team is studying. During the next few weeks, MIT scientists plan to test roboticsalamancders and robotic manta rays.
Whatever type of robot is being created, "the underwater environment is the most difficult environment for robotics," said Huosheng Hu, a professor of computer science and electronic engineering at the University of Essex. Hu has built his own realistic robotic fish which was on display at the London Aquarium.
Hu likes the new unibody robofish, but doesn't think that the new robofish have any particular new advantage in terms of three dimensional swimming, or at least won't until the additional actuators are installed.
Despite the current limitations of robofish, human engineers will continue to chase natural fish in terms of speed, maneuverability and endurance.
"We still have a long way to go to achieving the same performance as real fish," said Hu.
African Tree Makes Soils Rich for Crops
Aug. 28, 2009 -- A unique African tree could dramatically improve the yield of crops planted under its canopy by providing natural, renewable fertilizer, says a new study.
The tree has the potential to aid farmers throughout Africa, South America, and much of south and Southeast Asia, according to the researchers.
"Soil fertility is one of the major constraints to food production in sub-Saharan Africa, and nitrogen is one of the most limiting elements," said Lou Verchot of the Center for International Forestry Research in Bogor, Indonesia, who was not a part of the new study.
Conventional agriculture provides nitrogen through nitrogen-containing, man-made fertilizer, but it can be prohibitively expensive for subsistence farmers.
Enter Faidherbia albida, a close cousin of the acacia -- the iconic, flat-topped tree that dots the African Savannah. Faidherbia is one of several trees that can capture nitrogen from the air through its roots and incorporate it into its leaves.
But what makes it unique is that it grows in the dry season and drops its leaves come the rainy season, when crops start to grow.
"These trees drop their leaves right when the plants are needing nitrogen," Verchot said.
"It acts like a fertilizer factory," said Dennis Garrity, Director General of the World agroforestry center in Nairobi, who authored the report. "You get this rich leaf material which is great organic fertilizer produced free of charge in the fields."
"The trees turn absolutely skeletal in the wet season so that they don't compete for sunlight or water or nutrients," he added. Meanwhile, the leaves and nutritious pods serve as food for livestock during the dry season when everything else has shriveled up.
Presenting at the World Congress of Agroforestry in Nairobi this week, Garrity reported a three- to four-fold increase in maize yields underneath the Faidherbia canopy compared with crops outside the canopy in studies in Malawi and Zambia. Faidherbia also increased yields in sorghum, millet and cotton fields.
Garrity hopes to spread the word about the Faidherbia tree throughout the African continent and beyond. The tree is compatible with the climate and farming practices in India and the rest of south Asia, in Southeast Asia, and in parts of South America.
In Zambia and Malawi, where Faidherbia trees are most widely used, farmers plant the trees in a checkerboard pattern every 30 feet throughout the field.
Although the Faidherbia tree has a unique life cycle, it is just one example of the important role trees in sustainable agriculture, Garrity said.
In other findings released at the Congress, the World Agroforestry Center reports satellite measurements showing that half of the world's agricultural lands, home to more than half a billion people, contain more than ten percent tree cover.
This finding shows that farmers rely on trees to serve a number of needs, from animal fodder to timber to fruit and nut crops to maintaining biodiversity on the land.
"Hopefully this will increase awareness of how important trees out of forests are," Verchot told Discovery News. "Just focusing on improved crop productivity is not going to meet all the livelihood needs."
Despite the presence of significant numbers of trees on farmland, clearing forest for agriculture is still a major conservation concern, Garrity and Verchot agreed.
But, they point out, as the world works to reduce deforestation to prevent climate change, the resources derived from forest trees will have to come from somewhere -- like from trees on farmland.
"Trees outside of forests are going to take on an even more important role as we start trying to reduce the deforestation emissions to the atmosphere," Verchot said.
Evolutionary leap observed in mice
A community of blonde mice is giving US scientists a chance to study Darwin's theory of natural selection at work.
The blonde deer mice evolved over 8,000 years in America after they adapted to their sand dune surroundings. Scientists studying them have discovered that the variant of a single gene determines the colour of a mouse's coat.
Darker mice would have found it more difficult to evade predators and reproduce in the surroundings at Sand Hills, Nebraska. Blonde mice, though, would have been more likely to pass on the pale gene, which has now spread through the mice population.
Dr Catherine Linnen, from Harvard University, said: "We show that a single genetic change creates lighter coloration in these mice, and that this variant clearly arose recently, sometime after the formation of the Sand Hills."
"This work sheds new light on the forces affecting diversity in nature," said Dr Hopi Hoekstra, also from Harvard, who co-authored the research published today in the journal Science.
Computers Help Decode Ancient Texts
Aug. 27, 2009 -- An ancient, indecipherable text from the Indus Valley region is slowly being decoded with the help of a computer program, according to recent research.
Though it has yet to decrypt this mysterious language, the program may help to decipher other ancient texts whose meanings have been long since forgotten.
"The computer program operates on sequences of symbols, so it can be used to learn a statistical model of any set of unknown or known texts," said Rajesh Rao, a University of Washington professor of computer science and co-author of the paper published in the Proceedings of the National Academy of Sciences (PNAS).
"In fact, such statistical models have been used to analyze a wide variety of sequences ranging from DNA and speech to economic data."
Roughly 5,000 seals, tablets and amulets, filled with about 500 different symbols, were created somewhere between 2600 and 1900 B.C. by a people living in the Indus valley River.
Despite numerous attempts to decipher the symbols, a full translation has long eluded scientists. In fact, one recent paper even cast doubt on whether the Indus Valley script was even a written text at all, but rather political or religious symbols.
To start the search for what meaning the text might hold, American and Indian scientists input the symbols into a computer program and then ran a statistical analysis of the symbols and where they appear in the texts.
With that information, the program can do many things: create new, hypothetical Indus Valley texts, fill in missing symbols in existing texts, and tell the scientist if a particular text has been generated by their computer model.
"We used the latter to show that the Indus texts that have been discovered in West Asia are statistically very different from the texts found in the Indus Valley," said Rao, "suggesting that the Indus people used their script to represent different content or language when living in a foreign land."
For Asko Parpolo, a professor at the University of Helsinki and an expert on the Indus Valley script, the PNAS research helps prove that the symbols are indeed an early written language. It does little, however, to decipher the text.
The written of the ancient inhabitants of the Indus Valley might never be decoded, according to Parpolo, but computer modeling of unknown languages could help reveal their meaning as well, said Marcelo Montemurro, a scientist at the University of Manchester.
Using modern texts to validate this theory, Montemurro and his colleagues used computers and information theory to find the main topic of written works including Charles Darwin's On the Origin of Species and Herman Melville's Moby Dick. Not surprisingly, words like species, selection and islands were some of the top ten words in Origin of Species.
Montemurro now wants to test his model on an undeciphered Medieval Text known as the Voynich manuscript.
"The text is not long, but these methods can be applied so we can at least obtain a list of special words that would presumably convey the overall meaning of the texts," said Montemurro.
The technique "separates words like 'a' and 'the' that are frequent but not functional from words that presumably convey the overall meaning of the texts," said Montemurro. With the most significant symbols identified, scientists could then study those symbols intensively to decipher the language more quickly.
For now, however, the Indus Valley script and the Voynich manuscript, along with many other ancient texts, remain indecipherable, but scientists are hopeful that computers will eventually decode the symbols on them.
"There are some who say the (Indus Valley) script can never be deciphered without a bilingual text like the Rosetta Stone or really long texts," said Rao.
"I am however optimistic that given a few more years, we may be able to at least narrow down the language family of the script by using computer analysis to gain an in-depth understanding of the underlying grammar."
Ripe Fruit May Inspire Mosquito Repellents
Aug. 27, 2009 -- Fruit flies actually have a love-hate relationship with the smell of fruit. And a new insight into the chemistry of that attraction and repulsion could lead to novel repellients for other insects, researchers say.
Carbon dioxide is a known turn-off to fruit flies when it emanates from stressed peers. "Drosophila sniff CO2 and avoid it like crazy," says neurobiologist Anand Ray of the University of California, Riverside. But ripe fruit puffs out the gas and still attracts plenty of flies. In this case, compounds released by the fruit block the flies' CO2 receptors, Ray and Riverside colleague Stephanie Turner report online August 26 in Nature.
Mosquitos, in contrast, outright love CO2. They hunt down blood meals by following plumes of the exhaled gas. But as in fruit flies, a fruit compound can jam CO2 receptors in the notorious mosquitos Culex quinquefasciatus, the researchers say. This species spreads West Nile fever and the parasites that cause the huge limb swellings of the tropical disease filariasis. Ray proposes that compounds that could keep the mosquito detectors from sensing those plumes might render people hard to find. With a grant from the Bill and Melinda Gates Foundation, he's starting to test the strategy.
In fruit flies, the aversion to CO2 turned up when researchers shook the insects or zapped them with a little electric shock. The stressed flies released an odor with CO2 as a key component, and unharmed flies fled from that odor.
"There was this paradox," Ray says. The same fruit flies that avoid stressed flies and even unripe CO2-exhaling fruit, crowd around ripe fruit as well as other strong CO2 sources such as beer.
To study the contradiction, Ray and Turner turned to the sensory detectors on the insects' antennae. "Each antenna is shaped like a strawberry, with hundreds of tiny hairs on it," Ray says. Inserting minute electrodes into pores on some of the hairs let the researchers check for activity in a neuron bearing the the specialized receptor known to detect CO2. The researchers monitored that activity while releasing both fruit odors and CO2. Two of the fruit odors strongly reduced the neuron's reaction to CO2.
Those two inhibitor molecules, 1-hexanol and 2,3-butanedione, were quite a surprise, Ray says. "They do not look anything like CO2."
Yet he and Turner note that earlier studies show that as bananas ripen, concentrations of 1-hexanol increase by 777 percent and 2,3-butanedione by 4,900 percent.
To see whether the inhibitors indeed act on the receptor, "we took the awesome power of fly genetics," Ray says, and put the receptor protein in a neuron that normally has nothing to do with CO2 detection. Isolated in this alien neuron, the receptor still jammed when the inhibitors wafted by.
Mosquito neurons responded to one of the inhibitors, 1-hexanol. The 2,3-butanedione didn't produce much of a reaction but a closely related compound, 1-butanal, did, Ray and Turner found.
The new paper looks like a significant contribution toward developing new controls for disease-spreading insects, says neuroethologist Pablo Guerenstein of the Argentine National Research Council in Diamante and Entre Rios National University in Oro Verde, Argentina. Now, Guerenstein says, he wants to know more about the results' biological significance, such as whether the inhibitors affect the way insects perceive CO2 in the natural blend of odors from a fruit. Also, he points out that the inhibitory 1-hexanol appears in some vertebrate odors, and he would like to know about its role there.