Aquatic osteoporosis' jellifying lakes

Date:

November 19, 2014

Source:

Queen's University

Summary:

A plague of “aquatic osteoporosis” is spreading throughout many North American soft-water lakes due to declining calcium levels in the water and hindering the survival of some organisms. The reduced calcium availability is hindering the survival of aquatic organisms with high calcium requirements and promoting the growth of nutrient-poor, jelly-clad animals.

 

 A handful of Holopedium capsules which are replacing the water flea Daphnia due to declining calcium levels in many lakes.

 

A plague of "aquatic osteoporosis" is spreading throughout many North American soft-water lakes due to declining calcium levels in the water and hindering the survival of some organisms, says new research from Queen's University.

 

Researchers from Queen's, working with colleagues from York University and the University of Cambridge, as well as other collaborators, have identified a biological shift in many temperate, soft-water lakes in response to declining calcium levels after prolonged periods of acid rain and timber harvesting. The reduced calcium availability is hindering the survival of aquatic organisms with high calcium requirements and promoting the growth of nutrient-poor, jelly-clad animals.
In the study, researchers looked at the microscopic organisms (~1 mm) Daphnia and Holopedium -- the latter whose size is greatly increased by its jelly capsule.
"Calcium is an essential nutrient for many lake-dwelling organisms, but concentrations have fallen so low in many lakes that keystone species can no longer survive," says Adam Jeziorski, one of the lead authors of the study and a postdoctoral fellow in the Department of Biology at Queen's.
The research team found that when calcium levels are low, the water flea Daphnia, which has high calcium requirements, becomes less abundant. Importantly, this keystone species is being replaced by its jelly-clad competitor, Holopedium.
"Conditions now favour animals better adapted to lower calcium levels, and these changes can have significant ecological and environmental repercussions," says Dr. Jeziorski.
Tiny fossils from lake sediments were studied to determine the pre-impact conditions of the lakes as the calcium decline began before monitoring programs were in place. Using this technique, the team was able to examine the environmental trends from the past approximately 150 years.
"Lake sediments act like a history book of past changes in a lake, recording what happened before the problem was identified," says John Smol (Biology), Canada Research Chair in Environmental Change. "Jelly-clad invertebrates have been increasing in an alarming number of lakes. This is likely a long-term effect of acid rain on forest soils, logging and forest regrowth."
The increase in jelly-clad invertebrates can have important implications for lake biology, altering food webs, but can also clog water intakes.
"Many lakes we investigated have passed critical thresholds," says Dr. Smol. "We have been reduced to the role of spectator as these changes continue to unfold. Once again we see there are many unexpected consequences of our actions, most of which are negative."
This research was funded by the Natural Sciences and Engineering Research Council of Canada and the Ontario Ministry of the Environment and Climate Change.
The study is published in Proceedings of the Royal Society B.

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Story Source:
The above story is based on materials provided by Queen's University. The original article was written by Rosie Hales. Note: Materials may be edited for content and length.

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Why lizards have bird breath: Iguanas evolved one-way lungs surprisingly like those of birds

Date:

November 17, 2014

Source:

University of Utah

Summary:

Biologists long assumed that one-way air flow was a special adaptation in birds driven by the intense energy demands of flight. But now scientists have shown that bird-like breathing also developed in green iguanas – reptiles not known for high-capacity aerobic fitness. The finding bolsters the case that unidirectional bird-like flow evolved long before the first birds.

 

 University of Utah scientists have shown that green iguanas have bird-like breathing; air flows in a one-directional loop through their lungs. The discovery bolsters the case that this style of breathing evolved in a common ancestor of lizards, snakes, crocodiles and dinosaurs including birds.

 

 

 

Whether birds are breathing in or out, air flows in a one-directional loop through their lungs. This pattern was unexpected and for decades biologists assumed it was unique to birds, a special adaptation driven by the intense energy demands of flight.

But that view is wrong, according to University of Utah scientists who now have shown that bird-like breathing also developed in green iguanas -- reptiles not known for high-capacity aerobic fitness. The finding bolsters the case that unidirectional bird-like flow evolved long before the first birds, arising nearly 300 million years ago in a common ancestor of lizards, snakes, crocodiles and dinosaurs including birds.
"We thought we understood how these lungs work, but in fact most of us were completely wrong," says Colleen Farmer, an associate professor of biology at the U and lead author of the new study published today in Proceedings of the National Academy of Sciences. "People have made a lot of assumptions about how lungs work in animals such as reptiles and crocodiles but they never actually measured flow," she says.
In humans and other mammals, lungs have airways with a tree-like branching structure. A main trunk in each lung splits into branches and twigs. Air flows in and out in a tidal fashion. Oxygen and carbon dioxide pass to and from blood in tiny air sacs, called alveoli, at the tips of the smallest airway branches.
In bird lungs, air loops in one direction through a series of tubes lined with blood vessels for gas exchange. Aerodynamic forces act like valves to sustain the one-way flow through cycles of inhalation and exhalation.
"For years, people thought that the design evolved to meet the energetic demands of flight," Farmer says. "That's all wrong. Iguanas don't fly."
Alligators also have a bird-like pattern of airflow. Farmer and Kent Sanders, a radiologist at the U, revealed that in a 2010 study. It was the first evidence that one-directional lung ventilation might be an innovation pre-dating the origin of birds. Earlier this year, Farmer along with Emma Schachner and Robert Cieri at the U, and James Butler of Harvard University reported that monitor lizards have one-directional airflow through their lungs, too.
Those discoveries left open the possibility that crocs and monitor lizards evolved their bird-like lungs independently, that is, their evolution converged on a design similar to birds. The finding of bird-like lungs in yet another group of reptiles builds a stronger case for an origin in the remote past in a common ancestor.
To make the discovery, Farmer and co-authors Cieri, Schachner and Brent Craven of Pennsylvania State University had to find a way to visualize air moving through iguana lungs. In one set of experiments, they used a surgical scope to look inside the lungs of live iguanas as the lizards inhaled harmless smoke from a theatrical fog machine. They also used probes that measure air speed and volume in dissected lungs. Working from 3-D X-ray imaging of the contours of iguana lungs, Craven made a computer model simulating airflow. The model's predictions closely matched the patterns observed in real lungs. "It was dead-on with the directions of flow we observed," Farmer says.
The revelations make clear that scientists have much to learn about the physiology of lungs in species other than mammals. Textbooks generally assert that air moving in and out of lungs flows down a pressure gradient from a point of higher pressure to one of lower pressure, but Farmer says her group's findings show that in iguana lungs "that's not what's going on at all." The shapes and angles of the lung airways point jets of air that create one-directional flow.
The mechanics aren't fully known yet, but Farmer says a better understanding could inspire new ways to design devices that circulate or filter blood or other fluids without using mechanical valves. "The geometry of these lungs, it is so weird," Farmer says, "I don't think any engineer would dream that up."

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Story Source:
The above story is based on materials provided by University of Utah. Note: Materials may be edited for content and length.

Scientists employ satellite tags to solve whale-sized mystery

Date:

November 14, 2014

Source:

Wildlife Conservation Society

Summary:

For the first time, scientists working in the waters of Patagonia are using satellite tags to remotely track southern right whales from their breeding/calving grounds in the sheltered bays of Península Valdés, Argentina, to unknown feeding grounds somewhere in the western South Atlantic

 A WCS-led team member just after tagging a young southern right whale nick-named “Papillon.” The white markings are called callosities – large patches of raised tissue. Each whale’s callosities are unique and can be used to identify individual whales.






For the first time, scientists working in the waters of Patagonia are using satellite tags to remotely track southern right whales from their breeding/calving grounds in the sheltered bays of Península Valdés, Argentina, to unknown feeding grounds somewhere in the western South Atlantic. This could eventually provide clues to the cause of one of the largest great whale die-off ever recorded.

The international effort for answers includes members from the Wildlife Conservation Society (WCS), the Aqualie Institute of Brazil, the National Oceanic and Atmospheric Administration (NOAA), and Cascadia Research Collective, working in cooperation with Fundación Patagonia Natural, Instituto de Conservación de Ballenas, the University of California, Davis, the Dirección de Flora y Fauna (Wildlife Service), la Secretaría de Turismo, el Ministerio de Ambiente (Ministry of the Environment) of Argentina's Chubut Province.
The announcement was made as conservationists are holding the 2014 IUCN World Parks Congress in Sydney, Australia -- a once-in-a-decade global forum on protected areas.
Said Dr. Graham Harris, Director of WCS's Argentina Program: "A provincial protected area and a key area with a long history of work by WCS, Peninsula Valdés was declared a UNESCO Biosphere Reserve in June of 2014 due to its importance to protect both terrestrial wildlife and marine species along its waters. As the World Parks Congress in Sydney is underway, it is imperative to highlight the importance of protected areas like Peninsula Valdes to safeguard unique wildlife and habitats."
Over the past month, the team succeeded in affixing satellite transmitters to five southern right whales, a difficult task conducted during varying weather conditions in Golfo Nuevo, one of the two protected gulfs of Península Valdés and an important breeding ground for the southern right whale.
Over the past decade, southern right whale calves have died in unprecedented numbers (more than 400 between 2003-2011) for reasons still unclear to scientists. Different hypotheses for this mortality have been considered, including disease, certain types of contaminant, and harassment and wounding by kelp gulls, a frequent occurrence in Península Valdés.
This new research will help assess where the whales are feeding, namely if there could be any threats to the whales along their migration route or on their feeding grounds and if the research team can conduct additional tagging and studies to determine any issues associated with food or nutritional stress causing calf loss by some mothers.
Dr. Martín Mendez, Assistant Director of WCS's Latin America and the Caribbean Program, said: Over the last several centuries, and as recent as the 1960s, southern right whales were hunted, at times close to the verge of extinction. But they have now managed to rebound in numbers thanks to protected refuges such as Península Valdés. The recent increase in mortality is being caused by something that remains unsolved. Determining where the whales go to feed may offer clues to solving this complex question."
The deployed tags will transmit the geographical position and behavioral information of the animals up to Earth-orbiting satellites multiple times a day, allowing researchers to follow whales remotely. The researchers selected calving females and solitary juveniles for satellite tagging in order to glean insights into habitat use and migratory movements for different sex and age groups.
Sais Alex Zerbini, a whale telemetry expert from NOAA, Cascadia Research, and Aqualie Institute: "Satellite telemetry is the best method to understand the long-term movements and behavior of whales. Tagging individuals of different sex and age classes will let us explore potential differences in how they migrate and use their habitats."
Data accumulated thus far reveal unprecedented information for southern right whales: real-time information on long-range movements across marine regions. Two of the five whales have remained in the waters of Golfo Nuevo, while the other three have already left the bay. One of the animals is currently in deep waters of the South Atlantic, one has been spending its time over the continental shelf, and another has moved into deep offshore waters, but has returned to the continental shelf break. Movements from all whales have lead researchers to some areas where the tagged animals are likely feeding, and further discoveries of feeding grounds for this population may be revealed as the team tracks the movements of tagged animals.
Said Dr. Howard Rosenbaum of WCS's Ocean Giants Program: "The whales are currently in an area where former Soviet whaling expeditions killed more than 1,000 animals in the 1960s. Beyond these whaling records and other occasional sightings, the tagged animals in conjunction with whaling records will provide the best picture of the migration and feeding destinations for this population. As the tags continue to transmit, we hope our whales lead us to new insights about their lives in the vastness of the South Atlantic and provide possible clues related to the die-off."
Growing up to 55 feet in length and weighing up to 60 tons, the southern right whale is the most abundant species of the world's three species of right whale. Unlike the North Atlantic and North Pacific right whales (both Endangered), southern rights have managed to rebound from centuries of commercial whaling, with populations that have grown by as much as approximately seven percent annually since 1970. Of the estimated total population of southern right whales found throughout the entire Southern Hemisphere, around one third use the protected bays of Península Valdés as a breeding and calving habitat between the months of June and December.

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Story Source:
The above story is based on materials provided by Wildlife Conservation Society. Note: Materials may be edited for content and length.

Magnetic fields frozen into meteorite grains tell a shocking tale of solar system birth

Date:

November 13, 2014

Source:

Arizona State University

Summary:

Astrophysicists say that magnetic clues in a meteorite outline the earliest steps in the formation of the solar system and Earth-like planets.

 

 

 

 

 

 

 

(Magnetic field lines (green) weave through the cloud of dusty gas surrounding the newborn Sun. In the foreground are asteroids and chondrules, the building blocks of chondritic meteorites. While solar magnetic fields dominate the region near the Sun, out where the asteroids orbit, chondrules preserve a record of varying local magnetic fields)

 

 

The most accurate laboratory measurements yet made of magnetic fields trapped in grains within a primitive meteorite are providing important clues to how the early solar system evolved. The measurements point to shock waves traveling through the cloud of dusty gas around the newborn Sun as a major factor in solar system formation.

The results appear in a paper published Nov. 13 in the journal Science. The lead author is graduate student Roger Fu of MIT, working under Benjamin Weiss; Steve Desch of Arizona State University's School of Earth and Space Exploration is a co-author of the paper.
"The measurements made by Fu and Weiss are astounding and unprecedented," says Desch. "Not only have they measured tiny magnetic fields thousands of times weaker than a compass feels, they have mapped the magnetic fields' variation recorded by the meteorite, millimeter by millimeter."
Construction debris
It may seem all but impossible to determine how the solar system formed, given it happened about 4.5 billion years ago. But making the solar system was a messy process, leaving lots of construction debris behind for scientists to study.
Among the most useful pieces of debris are the oldest, most primitive and least altered type of meteorites, called the chondrites (KON-drites). Chondrite meteorites are pieces of asteroids, broken off by collisions, that have remained relatively unmodified since they formed at the birth of the solar system. They are built mostly of small stony grains, called chondrules, barely a millimeter in diameter.
Chondrules themselves formed through quick melting events in the dusty gas cloud -- the solar nebula -- that surrounded the young sun. Patches of the solar nebula must have been heated above the melting point of rock for hours to days. Dustballs caught in these events made droplets of molten rock, which then cooled and crystallized into chondrules.
Tiny magnets
As chondrules cooled, iron-bearing minerals within them became magnetized like bits on a hard drive by the local magnetic field in the gas. These magnetic fields are preserved in the chondrules even down to the present day.
The chondrule grains whose magnetic fields were mapped in the new study came from a meteorite named Semarkona, after the place in India where it fell in 1940. It weighed 691 grams, or about a pound and a half.
The scientists focused specifically on the embedded magnetic fields captured by "dusty" olivine grains that contain abundant iron-bearing minerals. These had a magnetic field of about 54 microtesla, similar to the magnetic field at Earth's surface, which ranges from 25 to 65 microtesla.
Coincidentally, many previous measurements of meteorites also implied similar field strengths. But it is now understood that those measurements detected magnetic minerals contaminated by Earth's magnetic field, or even from hand magnets used by meteorite collectors.
"The new experiments," Desch says, "probe magnetic minerals in chondrules never measured before. They also show that each chondrule is magnetized like a little bar magnet, but with 'north' pointing in random directions."
This shows, he says, they became magnetized before they were built into the meteorite, and not while sitting on Earth's surface.
Shocks and more shocks
"My modeling for the heating events shows that shock waves passing through the solar nebula is what melted most chondrules," Desch explains. Depending on the strength and size of the shock wave, the background magnetic field could be amplified by up to 30 times.
He says, "Given the measured magnetic field strength of about 54 microtesla, this shows the background field in the nebula was probably in the range of 5 to 50 microtesla."
There are other ideas for how chondrules might have formed, some involving magnetic flares above the solar nebula, or passage through the sun's magnetic field. But those mechanisms require stronger magnetic fields than what is measured in the Semarkona samples.
This reinforces the idea that shocks melted the chondrules in the solar nebula at about the location of today's asteroid belt, which lies some two to four times farther from the sun than Earth now orbits.
Desch says, "This is the first really accurate and reliable measurement of the magnetic field in the gas from which our planets formed."

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Story Source:
The above story is based on materials provided by Arizona State University. Note: Materials may be edited for content and length.

 

Bacteria become 'genomic tape recorders', recording chemical exposures in their DNA

Date:

November 13, 2014

Source:

Massachusetts Institute of Technology

Summary:

Engineers have transformed the genome of the bacterium E. coli into a long-term storage device for memory. They envision that this stable, erasable, and easy-to-retrieve memory will be well suited for applications such as sensors for environmental and medical monitoring

 MIT engineers have transformed the genome of the bacterium E. coli into a long-term storage device for memory. They envision that this stable, erasable, and easy-to-retrieve memory will be well suited for applications such as sensors for environmental and medical monitoring.

"You can store very long-term information," says Timothy Lu, an associate professor of electrical engineering and computer science and biological engineering. "You could imagine having this system in a bacterium that lives in your gut, or environmental bacteria. You could put this out for days or months, and then come back later and see what happened at a quantitative level."
The new strategy, described in the Nov. 13 issue of the journal Science, overcomes several limitations of existing methods for storing memory in bacterial genomes, says Lu, the paper's senior author. Those methods require a large number of genetic regulatory elements, limiting the amount of information that can be stored.
The earlier efforts are also limited to digital memory, meaning that they can record only all-or-nothing memories, such as whether a particular event occurred. Lu and graduate student Fahim Farzadfard, the paper's lead author, set out to create a system for storing analog memory, which can reveal how much exposure there was, or how long it lasted. To achieve that, they designed a "genomic tape recorder" that lets researchers write new information into any bacterial DNA sequence.
Stable memory
To program E. coli bacteria to store memory, the MIT researchers engineered the cells to produce a recombinase enzyme, which can insert DNA, or a specific sequence of single-stranded DNA, into a targeted site. However, this DNA is produced only when activated by the presence of a predetermined molecule or another type of input, such as light.
After the DNA is produced, the recombinase inserts the DNA into the cell's genome at a preprogrammed site. "We can target it anywhere in the genome, which is why we're viewing it as a tape recorder, because you can direct where that signal is written," Lu says.
Once an exposure is recorded through this process, the memory is stored for the lifetime of the bacterial population and is passed on from generation to generation.
There are a couple of different ways to retrieve this stored information. If the DNA is inserted into a nonfunctional part of the genome, sequencing the genome will reveal whether the memory is stored in a particular cell. Or, researchers can target the sequences to alter a gene. For example, in this study, the new DNA sequence turned on an antibiotic resistance gene, allowing the researchers to determine how many cells had gotten the memory sequence by adding antibiotics to the cells and observing how many survived.
By measuring the proportion of cells in the population that have the new DNA sequence, researchers can determine how much exposure there was and how long it lasted. In this paper, the researchers used the system to detect light, a lactose metabolite called IPTG, and an antibiotic derivative called aTc, but it could be tailored to many other molecules or even signals produced by the cell, Lu says.
The information can also be erased by stimulating the cells to incorporate a different piece of DNA in the same spot. This process is currently not very efficient, but the researchers are working to improve it.
"This work is very exciting because it integrates many useful capabilities in a single system: long-lasting, analog, distributed genomic storage with a variety of readout options," says Shawn Douglas, an assistant professor at the University of California at San Diego who was not involved in the study. "Rather than treating each individual cell as a digital storage device, Farzadfard and Lu treat an entire population of cells as an analog 'hard drive,' greatly increasing the total amount of information that can be stored and retrieved."
Bacterial sensors
Environmental applications for this type of sensor include monitoring the ocean for carbon dioxide levels, acidity, or pollutants. In addition, the bacteria could potentially be designed to live in the human digestive tract to monitor someone's dietary intake, such as how much sugar or fat is being consumed, or to detect inflammation from irritable bowel disease.
These engineered bacteria could also be used as biological computers, Lu says, adding that they would be particularly useful in types of computation that require a lot of parallel processing, such as picking patterns out of an image.
"Because there are billions and billions of bacteria in a given test tube, and now we can start leveraging more of that population for memory storage and for computing, it might be interesting to do highly parallelized computing. It might be slow, but it could also be energy-efficient," he says.
Another possible application is engineering brain cells of living animals or human cells grown in a petri dish to allow researchers to track whether a certain disease marker is expressed or whether a neuron is active at a certain time. "If you could turn the DNA inside a cell into a little memory device on its own and then link that to something you care about, you can write that information and then later extract it," Lu says.
The research was funded by the National Institutes of Health, the Office of Naval Research, and the Defense Advanced Research Projects Agency.