Three years ago, the same research team at Lund University observed that within the species common swift, (Apus apus) there were individuals that live in the air for up to ten consecutive months without landing — a world record for being airborne. A different research team has also shown that the alpine swift could live largely in the air.

In the current study, Anders Hedenström and his colleagues Susanne Åkesson, Gabriel Norevik, Arne Andersson and Johan Bäckman at Lund University, and Giovanni Boano from Italy, studied four individuals of the species pallid swift (Apus pallidus). The results show that the birds are in the air without landing for between two and three and a half months, depending on the individual.

Using micro-data loggers attached to the birds, the researchers measured movement when the wings flap. The loggers record activity every five minutes, and the bird’s location once a month. Using this method, the researchers have been able to ascertain that the birds live for months at a time in the air during the winter months, the period of the year they spend in West Africa after the breeding season in Italy.

“They land when they breed under a roof tile or in a hole, otherwise they live in the air. They eat insects while they fly, and when they have reached a high altitude and start gliding, they actually sleep for short periods,” says Anders Hedenström.

The breeding season dictates why pallid swifts cannot fly for as many months in a row as the common swift, i.e. ten months. Pallid swifts lay two clutches in one season, the common swift only one.

“However, it doesn’t actually matter if a species spends three or ten months in the air. Both are adapted to live in that element, they are designed to fly with maximised energy efficiency, regardless of whether they are flapping or gliding,” says Anders Hedenström, continuing:

“It’s always said, of course, that flying is birds’ most energy-intensive activity. I have calculated that a nightingale, which doesn’t live in the air in the same way at all, expends as much energy as a pallid swift, which is in the air all the time.”

Swifts have a high survival rate compared to many other birds. The researchers believe this is due to swifts spending such a large part of their lives in the air, where predators cannot surprise them in the same way as on the ground or in a nest. Also, when airborne they are not affected by parasites in the same way as on the ground.

Story Source:

Materials provided by Lund University. Note: Content may be edited for style and length.

Unlike thousands of tourists who trek to admire the park’s iconic geysers and hot springs every year, the WSU graduate student was traveling with a team of scientists to hunt for life within them.

After a strenuous seven mile walk through scenic, isolated paths in the Heart Lake Geyser Basin area, the team found four pristine pools of hot water. They carefully left a few electrodes inserted into the edge of the water, hoping to coax little-known creatures out of hiding — bacteria that can eat and breathe electricity.

After 32 days, the team returned to the hot springs to collect the submerged electrodes. Working under the supervision of Haluk Beyenal, Paul Hohenschuh Distinguished Professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Mohamed and postdoctoral researcher Phuc Ha analyzed the electrodes.

Voila! They had succeeded in capturing their prey — heat-loving bacteria that “breathe” electricity through the solid carbon surface of the electrodes.

The WSU team, in collaboration with colleagues from Montana State University, published their research detailing the multiple bacterial communities they found in the Journal of Power Sources.

“This was the first time such bacteria were collected in situ in an extreme environment like an alkaline hot spring,” said Mohamed, adding that temperatures in the springs ranged from about 110 to nearly 200 degrees Fahrenheit.

These tiny creatures are not merely of academic interest.

They may hold a key to solving some of the biggest challenges facing humanity — environmental pollution and sustainable energy. Such bacteria can “eat” pollution by converting toxic pollutants into less harmful substances and generating electricity in the process.

“As these bacteria pass their electrons into metals or other solid surfaces, they can produce a stream of electricity that can be used for low-power applications,” said Beyenal.

Most living organisms — including humans — use electrons, which are tiny negatively-charged particles, in a complex chain of chemical reactions to power their bodies. Every organism needs a source of electrons and a place to dump the electrons to live. While we humans get our electrons from sugars in the food we eat and pass them into the oxygen we breathe through our lungs, several types of bacteria dump their electrons to outside metals or minerals, using protruding hair-like wires.

To collect bacteria in such an extreme environment over 32 days, Mohamed invented a cheap portable potentiostat, an electronic device that could control the electrodes submerged in the hot springs for long periods of time.

“The natural conditions found in geothermal features such as hot springs are difficult to replicate in laboratory settings,” said Beyenal. “So, we developed a new strategy to enrich heat-loving bacteria in their natural environment.”

Story Source:

Materials provided by Washington State University. Note: Content may be edited for style and length.

“Much of the universe is made up of particles assembling,” said Heinrich Jaeger, the Sewell Avery Distinguished Service Professor of Physics, who co-authored a new study that appears in Nature Physics. “With acoustic levitation, we have a beautiful model system to study assembly at scales visible to the human eye, where we can track each particle with precision, and then relate the results to a wide range of often much more microscopic phenomena.”

Jaeger’s lab conducts innovative studies of the laws governing the interactions of particles — which they’ve used to create a robotic gripper to pick up almost any object and to explain a long-standing physics mystery that lets you run across the surface of a pool filled with water and corn starch.

In this case, the team was interested in the shape of prototypical clusters that form when, starting from a single particle, more are added one by one. They used sound waves to levitate plastic particles in midair — each about one millimeter in diameter, about the thickness of a penny — and studied how these particles interact with each other as they formed clusters, broke up and then reassembling into different configurations.

When there are five particles or fewer, they found, the particles cluster densely in only one configuration. However, when there are at least six particles, there are a number of different shapes they could assemble into when brought together tightly.

By using high-speed cameras to track the levitated particles, the researchers were able to capture these various configurations. They found that groups of six particles can form three distinct compact shapes: parallelogram, chevron and triangle. Adding one more particle to make seven meant that particles clustered together in one of four shapes, which scientists termed a flower, a turtle, a tree or a boat.

“Six particles is the minimum needed to change between different shapes, which is where things get interesting,” said co-first author Anton Souslov, then a UChicago postdoctoral researcher and now on the faculty at the University of Bath. “For us scientists, defying gravity to levitate dust also has this more fundamental interest of developing Earth-based experiments to understand how bodies in space like planets start to form.” This would be the very earliest stages, the scientists added, when the future planet is just a clump of space dust perhaps a centimeter across — before gravity starts to become a factor.

One unique aspect of the experiments is that the sound not only levitates the particles, but can also be used to affect how they interact as they float.

“A surprise was that by changing the sound wave frequency, we could manipulate the clusters and influence the shape that emerged,” said graduate student Melody Lim, the first author on the paper. Modeling the physics behind such acoustic forces, which was done by Souslov and professor of physics Vincenzo Vitelli, gives scientists a new means to control the assembly process.

They found that rearranging the shapes often depends on one particle acting as a “hinge” and swinging around the others to reconfigure, which could be very useful in a range of potential applications.

The research team now intends to look at how acoustic levitation can bring together larger numbers of particles to assemble more complex structures.

Story Source:

Materials provided by University of Chicago. Note: Content may be edited for style and length.

In a study publishing March 5 in Biophysical Journal, scientists report that electrical activity is the first known step in the tissue-regeneration process, starting before the earliest known genetic machinery kicks in and setting off the downstream activities of gene transcription needed to construct new heads or tails.

“It’s incredibly important to understand how cells make decisions about what to build,” says senior author Michael Levin, director of the Allen Discovery Center at Tufts University. “We’ve found that endogenous electrical signals enable cells to communicate and make decisions about their position and overall organ structure, so they know which genes to turn on.”

The species used in the study was Dugesia japonica. When parts of this flatworm are removed, the remaining tissues regrow the missing pieces at the correct ends — whether a head or a tail. Previous studies had shown that about six hours after amputation, the first genes associated with regrowing a missing part are turned on. But until now, it wasn’t known what happened before that or what mechanisms control which genes get turned on.

In the current experiments, led by Fallon Durant, who was a graduate student at the time, the heads and tails of the flatworms were removed. The researchers used voltage-sensitive fluorescent dyes that were able to indicate the various electrical potentials of the different regions. “You can literally see the electrical activity in the tissue,” Levin says. “Within a few hours of when this activity is seen, we can start to measure changes in gene expression.”

To show that a specific voltage pattern was responsible for turning on correct genes for each wound site, the team altered the resting potentials of cells at the different ends of the worms and observed the effects. By inducing ion flows that set each wound site to head- or tail-specific voltage patterns, they can create flatworms with two heads and no tail. They also studied the relationship between this electrical signal and the well-known Wnt protein signaling pathway, functioning downstream of the voltage-mediated decision machinery.

“Most of the people working on this problem study genetic and biochemical signals like transcription factors or growth factors,” Levin says. “We’ve decided to focus on electrical signals, which are a very important part of cell-to-cell communication.” He compares the electrical signals his group studies to those that occur in the brain. “A stimulus comes in and an electrical event triggers biochemical second-messenger events in the cells and downstream activity of the electrical network, such as decision making or forming a memory,” he notes. “This electrical system is super ancient and very highly conserved.”

Future research will focus on breaking down these signals in much more detail. For example, researchers would like to know how regenerated tissues make decisions about the size, shape, and scale of the new parts that they grow and how the bioelectric circuits store changes in body patterning, as is seen in two-headed worms that continue to make two-headed animals in subsequent rounds of regeneration.

“With perhaps the exception of infectious disease, the majority of problems in health and biomedicine hinge on understanding how cells get together to build a specific organ or other structure,” Levin concludes. “If we can figure out how to manipulate these processes, we can start to develop ways to correct birth defects and address everything from traumatic injury to degenerative diseases, aging, and cancer.”

Story Source:

Materials provided by Cell Press. Note: Content may be edited for style and length.