Does the Milky Way move like a spinning top?

INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC)

Research News

VIDEO: THE ROTATION OF THE GALAXY IS NOT INCLUDED IN THE VIDEO, ONLY THE PRECESSION WITH RESPECT TO IT. view more 

CREDIT: GABRIEL PÉREZ DÍAZ, SMM (IAC)

An investigation carried out by the astrophysicists of the Instituto de Astrofísica de Canarias (IAC) ?ofia Chrobáková, a doctoral student at the IAC and the University of La Laguna (ULL), and Martín López Corredoira, questions one of the most interesting findings about the dynamics of the Milky Way in recent years: the precession, or the wobble in the axis of rotation of the disc warp is incorrect. The results have just been published in The Astrophysical Journal.

The Milky Way is a spiral galaxy, which means that it is composed, among other components, of a disc of stars, gas and dust, in which the spiral arms are contained. At first, it was thought that the disc was completely flat, but for some decades now it is known that the outermost part of the disc is distorted into what is called a "warp": in one direction it is twisted upwards, and in the opposite direction downwards. The stars, the gas, and the dust are all warped, and so are not in the same plane as the extended inner part of the disc, and an axis perpendicular to the planes of the warp defines their rotation.

In 2020, an investigation announced the detection of the precession of the warp of the Milky Way disc, which means that the deformation in this outer region is not static, but that just like a spinning top the orientation of its axis is itself rotating with time. Furthermore, these researchers found that it was quicker than the theories predicted, a cycle every 600-700 million years, some three times the time it takes the Sun to travel once round the centre of the Galaxy.

CAPTION

The rotation of the Galaxy is not included in the video, only the precession with respect to it.

CREDIT

Gabriel Pérez Díaz, SMM (IAC)

Precession is not a phenomenon which occurs only in galaxies, it also happens to our planet. As well as its annual revolution around the Sun, and its rotation period of 24 hours, the axis of the Earth precesses, which implies that the celestial pole is not always close to the present pole star, but that (as an example) 14,000 years ago it was close to the star Vega.

Now, a new study by ?ofia Chrobáková and Martín López Corredoira has taken into account the variation of the amplitude of the warp with the ages of the stars. The study concludes that, using the warp of the old stars whose velocities have been measured, it is possible that the precession can disappear, or at least become slower than what is presently believed. To arrive at this result the researchers have used data from the Gaia Mission of the European Space Agency (ESA), analysing the positions and velocities of hundreds of millions of stars in the outer disc.

"In previous studies it had not been noticed", explains ?ofia Chrobáková, a predoctoral researcher at the IAC and the first author of the article, "that the stars which are a few tens of millions of years old, such as the Cepheids, have a much larger warp than that of the stars visible with the Gaia mission, which are thousands of millions of years old".

"This does not necessarily mean that the warp does not precess at all, it could do so, but much more slowly, and we are probably unable to measure this motion until we obtain better data", concludes Martín López Corredoira, and IAC researcher and co-author of the article.

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Article: ?ofia Chrobáková & Martín López Corredoira. "A case against a significant detection of precession in the Galactic warp". The Astrophysical Journal. DOI: https://iopscience.iop.org/article/10.3847/1538-4357/abf356

- Arxiv: https://arxiv.org/abs/2105.04348

 

China's PM2.5 pathways under carbon neutrality goals

SCIENCE CHINA PRESS

Research News

IMAGE: ACCESSIBILITY OF FUTURE CLIMATE TARGETS AND AIR QUALITY IMPROVEMENTS OVER CHINA. ESTIMATES OF FUTURE CO2 EMISSIONS AND PM2.5 EXPOSURE UNDER DIFFERENT MITIGATION PATHWAYS IN 2030 (A) AND 2060 (B). THE... view more 

CREDIT: ©SCIENCE CHINA PRESS

China's clean air policies have substantially reduced PM2.5 air pollution in recent years. Yet >99% of Chinese population is still exposed to PM2.5 concentrations in excess of the World Health Organization (WHO) Air Quality Guidelines of 10 μg/m3. Climate actions targeting to reduce fossil fuel consumption also have substantial air quality benefits. The announcement of ambitious climate commitment to achieve carbon neutrality by 2060 may fuel the power to long-term air quality improvement in China.

Combining Global/China's climate mitigation pathways (i.e. global 2°C- and 1.5°C-pathways, NDC pledges, and carbon neutrality goals) and local clean air policies, Chinese energy system, anthropogenic emissions and PM2.5 air quality pathways from 2015 to 2060 are assessed. If the government improves the source treatment--promote the renewable energy fraction, push the production peaks of high consumption industries (e.g., iron, steel, cement), accelerate the phasing out of scattered coal; meanwhile continue to promote the in-depth end-of-pipe control in high-polluted industries, diesel-fueled vehicles and engines, and VOC-related industries, China would meet the NDC climate target in 2030, as well as mitigate the national population-weighted PM2.5 concentrations to ~28 μg/m3, achieving the national air quality standards.

However, the benefits of end-of-pipe control reductions are mostly exhausted by 2030, and reducing PM2.5 exposure of the majority of the Chinese population to below 10 μg/m3 by 2060 will likely require more ambitious climate mitigation efforts such as China's carbon neutrality goals and global 1.5°C-pathways. As the solution, by 2060, China will complete the transformation of low-carbon energy, with the dominate role of renewable energy (i.e. the renewable energy power generation would account for more than 70%, the fraction of coal would be less than 15% in industry sector, electricity and hydrogen vehicles would account higher than 60%). Such in-depth energy transition would lower China's carbon emissions by 90%. As a result, the average annual exposure level of PM2.5 will be around 8 μg/m3, lower than the WHO guideline and the air pollution problem has been fundamentally solved.

Cheng et al. proposes practical strategies to address both air pollution and GHGs emissions in the near-term, in which co-control measures focusing on co-emitted sources (i.e. fossil fuel consumption), co-management mechanism on PM2.5 and O3 pollution, and co-development plan on low carbon economy and clean energy transition are prioritized. China's future clean air pathways should transform from end-of-pipe control to energy and economic system optimization. Meanwhile, China should proactively promote the air quality standards to gradually integrate with the relevant WHO standards 10 μg/m3 as a new long-term goal, to accelerate the implementation of carbon neutrality strategy.

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See the article:

Pathways of China's PM2.5 air quality 2015-2060 in the context of carbon neutrality. Cheng J et al. National Science Review, https://doi.org/10.1093/nsr/nwab078

 

Brain's memory center stays active during 'infantile amnesia'

YALE UNIVERSITY

Research News

 

One trait shared by all humans is that they don't remember specific life episodes that occurred before the age of 3 or 4. Many scientists have attributed this so-called "infantile amnesia" to a lack of development in the hippocampus, an area of the brain located in the temporal lobe that is crucial to encoding memory.

However, a new brain imaging study by Yale scientists shows that infants as young as three months are already enlisting the hippocampus to recognize and learn patterns. The findings were published May 21 in the journal Current Biology.

"A fundamental mystery about human nature is that we remember almost nothing from birth through early childhood, yet we learn so much critical information during that time -- our first language, how to walk, objects and foods, and social bonds," said Nick Turk-Browne, a professor of psychology at Yale and senior author of the paper.

For the new study, the Yale team used a new functional magnetic resonance imaging (fMRI) technology to capture activity in the hippocampus in 17 babies, aged three months to two years old, as they were presented two sets of images on a screen. One set of images appeared as a structured sequence containing hidden patterns that could be learned. In the other, images appeared in a random order that offered no opportunity for learning. After the babies were shown these two sets of images several times, the hippocampus responded more strongly to the structured image set than to the random image set.

What might be happening, Turk-Browne said, is that as a baby gains experience in the world, their brain searches for general patterns that help them understand and predict the surrounding environment. This happens even though the brain is not equipped to permanently store each individual experience about a specific moment in space and time - the hallmark of episodic memory that is also lost in adult amnesia.

The strategy makes sense because learning general knowledge -- such as patterns of sounds that make up the words in a language -- may be more important to a baby than remembering specific details, such as a single incident in which a particular word was uttered.

The size of the hippocampus doubles in the first two years of life and eventually develops connections necessary to store episodic memories, Turk-Browne said.

"As these circuit changes occur, we eventually obtain the ability to store memories," he said. "But our research shows that even if we can't remember infant experiences later on in life, they are being recorded nevertheless in a way that allows us to learn from them."

Yale's Cameron Ellis is first author of the study, and this research was included in his recently completed and award-winning PhD dissertation.

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Infants recognize rapid images, just like adults

CHUO UNIVERSITY

Research News

 

IMAGE: INFANTS COULD IDENTIFY TWO FACES WHEN THE TEMPORAL INTERVAL BETWEEN THEM WAS 800 MS, BUT THEY COULD IDENTIFY ONLY THE FIRST TARGET (OVERLOOKED THE SECOND TARGET) WHEN THE SEPARATION WAS... view more 

CREDIT: CHUO UNIVERSITY

It has previously been reported that human visual system has a temporal limitation in processing visual information when perceiving things that occur less than half a second apart. This temporal deficit is known as "attentional blink" and has been demonstrated in a large number of studies. These studies reported that adults could recognize two things when these two were temporally separated over 500 ms, but adults overlooked the second thing when the temporal interval was less than 500 ms. Recently, this attentional blink phenomenon has been observed in even preverbal infants less than one-year old.

In the study from Chuo University, Japan Women's University, and Hokkaido University, infants aged 7 and 8 months were required to identify two female faces among images of sceneries which were presented successively at a rate of 100 ms per image. In one set of images, the faces were placed 200 ms apart; in the other, they were placed 800 ms apart. Researchers found that infants could identify two faces when the temporal interval between these two faces was 800 ms. Furthermore, infants overlooked the second face when the separation was 200 ms, suggesting that they exhibited the attentional blink phenomenon. These results suggest that infants take less than a second to completely process visual information and have the same temporal limitation in processing visual information as seen in adults.

"This is the first study revealing the attentional blink in preverbal infants and provides opportunities to further investigate the visual awareness in infants focusing on the attentional blink phenomenon. This phenomenon is of especial interest as, it has recently been used as a consciousness marker," said Shuma Tsurumi from Chuo University.

Jun-ichiro Kawahara, a professor at Hokkaido University said, "Our study demonstrated what is happening at the first half-second when infants see multiple visual objects. This contrasts sharply against previous studies that mainly focused on visual learning at much longer periods, such as an order of 5 seconds." He continued, "Moreover, our study could provide a new way to test whether existing theories of the attentional blink phenomenon can hold for underdeveloped infants."

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The study, published in Cognition, was supported by a Grant-in-Aid from the Japan Society for the Promotion of Science (JSPS) Fellows (19J21422), a Grant-in-Aid for Scientific Research on Innovative Areas, ''Construction of the Face-Body Studies in Transcultural Conditions" (17H06343), from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), and a Grant-in-Aid for Scientific Research (B) from the JSPS (19H01774).

Joint press release by Chuo University and Hokkaido University

 

First-of-its-kind flower smells like dead insects to imprison 'coffin flies'

First plant found to deceive pollinators by mimicking decomposing insects

FRONTIERS

Research News

 

IMAGE: A. MICROSTOMA FLOWERS HALF-BURIED IN THE GROUND (A) OR INCONSPICUOUS AMONG LITTER (B) OR ROCKS (C,D) view more 

CREDIT: CREDIT: T. RUPP, B. OELSCHLÄGEL, K. RABITSCH ET AL.

The plant Aristolochia microstoma uses a unique trick: its flowers emit a fetid-musty scent that seems to mimic the smell of decomposing insects. Flies from the genus Megaselia (family Phoridae) likely get attracted to this smell while searching for insect corpses to mate over and lay their eggs in. When they enter a flower, they are imprisoned and first pollinate the female organs, before being covered with pollen by the male organs. The flower then releases them unharmed.

"Here we show that the flowers of A. microstoma emit an unusual mix of volatiles that includes alkylpyrazines, which are otherwise rarely produced by flowering plants. Our results suggest that this is the first known case of a flower that tricks pollinators by smelling like dead and rotting insects rather than vertebrate carrion," says corresponding author Prof Stefan Dötterl, the head of plant ecology group and the Botanical Gardens at the Paris-Lodron University of Salzburg, Austria. The study is published in the open access journal Frontiers in Ecology and Evolution.

Between 4-6% of flowering plants use a 'deceptive pollination strategy': they use odor, color, and touch to advertize a reward to pollinators, such as nectar, pollen, or mating and breeding sites, but don't actually give any. The deception works because pollinators are poor at distinguishing between the reward and the mimic. Deceptive pollination is typical of many orchids, but has also independently evolved in other plants, including in the genus Aristolochia (family Aristolochiaceae or birthworths).

"Aristolochia contains over 550 species around the world, especially in the tropics and subtropics. They are mostly woody vines and herbaceous perennials with striking, complex flowers that temporarily imprison their visitors to get pollinated," says Prof Christoph Neinhuis, coauthor of the study, who cultivates one of the largest Aristolochia collections worldwide at TU Dresden Botanical Garden, Germany.

When pollinators enter an Aristolochia flower, they are guided by hairs downwards to a small chamber which holds the sexual organs. Trapped inside, they deposit any pollen they carry onto the female organs, before the stamens ripen and release more pollen. When the hairs that block the entrance to the chamber wither, the pollinators can escape, and a new cycle can begin.

"Many Aristolochia species are known to attract flies with floral scents, for example mimicking the smell of carrion or feces of mammals, decaying plants, or fungi," says first author Thomas Rupp, a PhD student at the Paris-Lodron University of Salzburg. "But our curiosity was piqued by A. microstoma, a species known only from Greece: unlike other Aristolochia with their showy flowers, A. microstoma has inconspicuous brownish flowers that lie horizontally, partly buried or close to the ground among leaf litter or rocks. The flowers release an unpleasant, carrion-like smell, noticeable to people at a short distance."

Rupp and colleagues sampled A. microstoma plants from three sites in Greece: one West of Athens and two on the Peloponnese. From 1457 flowers (of which 72% were in the first, female phase) they collected a total of 248 arthropods, ranging from flies from four families to centipedes and springtails. Only female and male Megaselia flies - M. scalaris and members of the M. angusta/longicostalis cluster of closely related species, as determined through DNA barcoding and from morphology - were found carrying pollen inside its flowers, indicating that they are the normal pollinators.

The authors then used gas chromatography with mass spectrometry (GC/MS) to analyze the flowers' scent 'bouquet'. They found 16 compounds, including strong-smelling nitrogen- and sulfur-bearing volatile molecules. Among the main 'ingredients' were oligosulfides, produced by many plant species whose pollinators are carrion flies or bats: a fetid scent characteristic of decomposing meat. But surprisingly, another was 2,5-dimethylpyrazine (8-47% of total composition), a musty scent typical of cooked rice or roasted peanuts - known in nature to occur in the carapace of decomposing beetles and well as in the urine of rodents. Very few plants are known to produce this compound, strongly suggesting that A. microstoma mimics an unusual fake 'reward' to attract specialist pollinators.

"Earlier studies had suggested that A. microstoma might be pollinated by leaf litter-dwelling insects such as ants, because of the orientation and position of the flowers. But here we show that this isn't correct: instead, the main pollinators are Megaselia 'coffin flies'. As their name suggests, these flies feed on carrion, on which they lay their eggs and which serves as food for the larvae, which is why they are often used as evidence in forensic medicine," says Dötterl.

"We show A. microstoma flowers emit a simple but highly unusual mix of scents that includes 2,5-dimethylpyrazine, a molecule that occurs neither in vertebrate carcasses nor in feces, but does occur in dead beetles. We conclude that A. microstoma likely uses a strategy that has never been reported before: its flowers mimic the smell of invertebrate carrion to attract and imprison pollinators. The peculiar orientation of the flowers close to the ground may also help, as pollinating coffin flies search for breeding sites or food close to the ground, in leaf litter or between rocks," concludes coauthor Prof Stefan Wanke from TU Dresden, Germany.

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Finding the first flower from Northwest China

SCIENCE CHINA PRESS

Research News

 

IMAGE: A-B. PART AND COUNTERPART OF HOLOTYPE OF GANSUFRUCTUS SALIGNA GEN. ET SP. NOV. SHOWING LEAFY AXES WITH INFRUCTESCENCES AND LANCEOLATE LEAVES. C-D, PART AND COUNTERPART SHOWING AXES WITH ALTERNATE ARRANGED... view more 

CREDIT: ©SCIENCE CHINA PRESS

"Abominable mystery" -- the early origin and evolution of angiosperms (flowering plants) was such described by Charles Robert Darwin. So far, we still have not completely solved the problem, and do not know how the earth evolved into such a colorful and blooming world.

Recently, a new angiosperm was reported based on numerous exceptionally well-preserved fossils from the Lower Cretaceous of Jiuquan Basin, West Gansu Province, Northwest China. The new discovery is the earliest and unique record of early angiosperms in Northwest China. The study has been accepted for publication in the journal National Science Review and is currently available online at https://doi.org/10.1093/nsr/nwab084.

The new angiosperm was named Gansufructus saligna, and all the fossil specimens were collected from the grayish green mudstone of the upper Zhonggou Formation in Hanxia Section. Remarkably, the plant fossils are almost completely preserved with branched axes, attached leaves and paniculate infructescences, providing valuable materials for the morphological studies of early angiosperms.

Gansufructus saligna is erect and graceful, three to four times branched, with alternate arranged axes and leaves. Leaves are simple and willow-shaped, leaf margin is entire, leaf apex is acute and leaf base is decurrent and estipulate with short petiole. Leaf venation is poorly organized with low-rank venations, primary vein prominent, secondary veins pinnate, and tertiary veins reticulate. The infructescences are loose panicles bearing fruits in different stages of maturity. Each fruit is formed from four basally syncarpous carpels borne in a whorle arrangement. And each carpel subtended by a small and persistent tepal at the base and contains three to five anatropous seeds.

Gansufructus saligna is supposed to be a small, slender plant with flexible stems, delicate leaves and paniculate infructescences, and is suggested to be a terrestrial herbaceous eudicot based on the morphology of both vegetative and reproductive organs. It probably grew along the lakeshores, where the environment is low-lying and humid. Moreover, the current fossil specimens together with other fossil records of early angiosperms from the Jehol biota and other regions, indicate that the presence of diverse early eudicots of low stature colonizing areas during the middle-late Early Cretaceous. This study is of great significance in exploring the origin, evolution, diversity and habitat preferences of early eudicots.

See the article:

An Exceptionally Well-Preserved Herbaceous Eudicot from the Early Cretaceous (late Aptian-early Albian) of Northwest China  https://doi.org/10.1093/nsr/nwab084

CAPTION

A new eudicot, Gansufructus saligna gen. et sp. nov. is reported from the late Early Cretaceous of Gansu, Northwest China, based on numerous exceptionally well-preserved axes with leaves and infructescences. It is the earliest and unique record of early angiosperms in Northwest China. Morphological studies indicated that Gansufructus saligna is a terrestrial herb growing in lowland humid areas. The new discovery is significant for exploring the origin, evolution, diversity, and habitat preferences of early eudicots.

CREDIT

©Science China Press

 Who's in this ocean? Tracking down species on the go using environmental DNA

TOHOKU UNIVERSITY

Research News

 

IMAGE: CASSIOPEA IS AN UPSIDE-DOWN JELLYFISH THAT RESTS ON THE BOTTOM OF THE SEAFLOOR view more 

CREDIT: ANDRE MORANDINI

Sloughed off skin and bodily fluids are things most people would prefer to avoid.

But for marine biologist like Cheryl Lewis Ames, Associate Professor of Applied Marine Biology in the Graduate School of Agricultural Science at Tohoku University (Japan), such remnants of life have become a magical key to detecting the unseen.

Any organism living in the ocean will inevitably leave behind traces containing their DNA - environmental DNA (eDNA) - detectable in water samples collected from the ocean

Only recently has molecular sequencing technology become advanced enough to conduct eDNA analysis in the field to identify species that may be endangered, invasive or dangerous, and could otherwise go unnoticed.

Ames chose sampling sites in the Florida Keys (USA) where species of upside-jellyfish Cassiopea occur to test out their newly developed Fieldable eDNA sequencing kit - called FeDS.

Using eDNA for multiple species identification is a multistep process known as metabarcoding. Since the mixed DNA template must first be amplified using the polymerase chain reaction (PCR), metabarcoding experiments in the field have only recently been possible thanks to battery-operated thermocyclers and other portable devices.

Determining the identity of a species from small bits of DNA filtered from seawater requires the use of a Next Generation Sequencer (NGS), a machine that traditionally takes up the whole desktop counter in a laboratory and requires an electrical outlet. A novelty of the portable technology used in this study - Nanopore MinION -- is that as pieces of DNA pass through a microscopic pore in the device, differences in electrical current determine the unique code of each DNA strand.

Instead of the typically large sequencing machines used to complete such a task, Ames and her team were testing a Nanopore system the size of a cellphone, powered by a laptop computer. A drop of the prepared eDNA mixture added to the portable sequencer reveals on the screen the genetic code of all the DNA passing through it in real-time.

Then, DNA sequences are searched against a huge database of sequences to determined which species are represented by the eDNA collected onsite that day. Upgraded "offline" versions of the necessary software and pre-downloading of the reference database to the laptop meant that the whole metabarcoding process could be conducted beyond the walls of a laboratory, away from internet connection.

Ames and the team detected 53 species of jellyfish including Cassiopea, the upside-down jellyfish, two venomous species of box jellyfish, many species with hydroid forms, and two species of stalked jellyfish which were previously unreported in the Florida Keys, indicating that the process could reveal species that would otherwise go unnoticed.

"My hope is that one day this system is used for sting mitigation, almost like a weather forecast app that also reports 'jellyfish stings risk' at certain beaches," said Ames.

Ames has spent much of her time conducting research in areas where jelly stings are common, and warnings about whether venomous jellies are in the area could prevent countless injuries to swimmers. Besides practical purposes in fisheries and conservation, the fact that a sample of ocean water can reveal the organisms in the vicinity is truly a marvel.

CAPTION

Nanopore sequencing experiment being conducted in a rental car in this study

CREDIT

Cheryl L Ames

CAPTION

Ames carefully fills the sequencer with the eDNA solution with assistance from coauthor Ohdera (Florida Keys, USA). ©Cassiopea Model Group

CREDIT

Cassiopea Model Group

Telling up from down: How marine flatworms learn to sense gravity

Zoologists explore the mechanism and development of gravity-sensing ability in marine acoel flatworms

OKAYAMA UNIVERSITY

Research News

 

IMAGE: SENSORY ORGAN OF THE ACOEL FLATWORM PRAESAGITTIFERA NAIKAIENSIS. SHOWN HERE IS A LIGHT MICROGRAPH OF THE WHOLE BODY (LEFT), AND ITS ENLARGED ANTERIOR REGIONS (RIGHT), INCLUDING THE CILIATED EPIDERMIS WITH... view more 

CREDIT: 2021 OKAYAMA UNIVERSITY

All living organisms are equipped with sensory organs to detect changes in their surrounding environment. It may not immediately strike us as obvious but, similar to how we can sense heat, cold, light, and darkness, we are also extremely adept at sensing gravity. In our case, it is our inner ear that does this job, helping us maintain balance, posture, and orientation in space. But, what about other organisms, for instance invertebrates that lack a backbone?

The gravity sensing organ in some aquatic invertebrates, known as a "statocyst," is, in fact, rather fascinating. The statocyst is essentially a fluid-filled sac with sensory cells lining its inner wall and a small, mineralized mass called "statolith" contained inside. During any body movement, the statolith moves and consequently comes in contact with sensory cells in the inner wall, deflecting them. The deflections, in turn, activate the neurons (nerve cells), which then relay signals to the brain about changes in body orientation.

However, exactly how the sensory cells stimulate the neurons is not particularly clear for acoel flatworms--soft-bodied, marine animals with a simple anatomy, which represent one of the earliest extant life forms with bilateral (left-right) symmetry. What zoologists know so far, based on the finding that juvenile acoel flatworms occasionally fail to sense gravity, is that the ability is acquired sometime after hatching from the eggs.

In a new study published in Zoomorphology, scientists from Okayama University, Japan led by Prof. Motonori Ando have now taken a stab at understanding these curious creatures better. But what exactly is so attractive about acoel flatworms? Prof. Ando explains, "Understanding the stimulus response mechanism of Acoela can uncover a fundamental biological control mechanism that dates back to the origin of bilaterian animals, including humans. These organisms, therefore, are key to unravelling the process of evolution."

For their study, the scientists used an acoel species called Praesagittifera naikaiensis or P. naikaiensis that is endemic to the Seto Island Sea coasts at Okayama. "The mysterious body plan of P. naikaiensis could be key to connecting Okayama and the world's natural environment," says Prof. Ando.

To examine the relationship between the statocyst and nervous system of P. naikaiensis, the scientists had to make them both visible, a task usually accomplished by a "marker" or a "label." However, due to a lack of any suitable label for the statocyst, they adopted a different strategy in which they labeled instead the basal lamina, the layer on which the sensory cells sit. As for the nervous system, they labeled the nerve terminals using a well-known marker. Finally, they studied the specimen using confocal microscopy, a technique in which light is focused on to a defined spot at a specific depth to stimulate only local markers.

The results were illuminating. The scientists found that the acoel flatworm developed a gravity-sensing ability within 0 to 7 days after hatching, with the statolith forming after hatching. The statocyst comprised longitudinal and transverse nerve cords, forming what is called a "commissural brain" and a "statocyst-associated-commissure" (stc) characterized by transverse fibers. They hypothesized that a gravity-sensing ability developed when: 1) the statolith acquired a sufficient concentration of calcium salts, 2) stc functioned as the signal-relaying neurons, and 3) the sensory cells were present outside the sac and stimulated indirectly by the statolith through the basal lamina and stc.

Inspired by these findings, Prof. Ando has envisioned future research directions and even practical applications of their study. "It has been reported that closely related species of this organism inhabit the North Sea coast, the Mediterranean coast, and the east coast of North America. Since there is great interest about the commonality of their habitats, we can extend our research to a more global level, using these animals as a novel bioassay system for the environment they live in, especially in the face of the accelerated pace of climate change and anthropogenic habitat degradation. Furthermore, acoel flatworms could be an excellent biological model for studying diseases caused in humans due to abnormalities of sensory hair cells," says an excited Prof. Ando.

It seems modern science is just warming up to the myriad mysteries of this minute worm!

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"Scuba-diving" lizards use bubble attached to snout to breathe underwater

BINGHAMTON UNIVERSITY

Research News

 

IMAGE: ANOLIS LIZARD REBREATHES EXHALED AIR UNDERWATER USING A BUBBLE CLINGING TO THEIR SNOUTS. view more 

CREDIT: LINDSEY SWIERK

BINGHAMTON, N.Y. - A team of evolutionary biologists including faculty at Binghamton University, State University of New York have shown that some Anolis lizards, or anoles, have adapted to rebreathe exhaled air underwater using a bubble clinging to their snouts.

Semi-aquatic anoles live along neotropical streams and frequently dive for refuge, remaining underwater for up to 16 minutes. Lindsey Swierk, assistant research professor of biological sciences at Binghamton University, documented this behavior in a Costa Rican anole species in 2019. She had been shocked to see an anole submerge itself for such long periods and used a GoPro underwater to document the behavior.

"It's easy to imagine the advantage that these small, slow anoles gain by hiding from their predators underwater - they're really hard to spot!" says Swierk. "But the real question is how they're managing to stay underwater for so long."

The researchers conducted experiments documenting routine air-based underwater respiration in several distantly related semi-aquatic anole species. They found that semi-aquatic anoles can respire underwater by ''rebreathing'' exhaled air that is trapped between their skin and surrounding water.

"We found that semi-aquatic anoles exhale air into a bubble that clings to their skin," said lead author Chris Boccia, a recent master of science graduate from the University of Toronto. "The lizards then re-inhale the air, a maneuver we've termed 'rebreathing' after the scuba-diving technology."

The researchers believe that hydrophobic skin, which they observed in all sampled anoles, may have been exaptative, facilitating the repeated evolution of specialized rebreathing in species that regularly dive. Their analyses strongly suggest that specialized rebreathing is adaptive for semi-aquatic habitat specialists. Air-based rebreathing may enhance dive performance by incorporating dead space air from the buccal cavity or plastron into the lungs, facilitating clearance of carbon dioxide, or allowing uptake of oxygen from surrounding water (i.e., a ''physical gill'' mechanism.) The team used an oxygen sensor inside the rebreathed bubbles to determine whether anoles were consuming oxygen from the bubble. In true "scuba-tank" fashion, the researchers discovered that the oxygen concentration in an anole's air bubble decreases over the length of the dive, in support of this idea.

"The finding that different species of semi-aquatic anoles have evolutionarily converged to extract oxygen from their rebreathed air bubbles leads to other exciting questions," says Swierk. "For example, the rate of oxygen consumption from the bubble decreases the longer an anole dives, which could possibly be explained a reduction in an anole's metabolic rate with increased dive time." Binghamton graduate student co-author, Alexandra Martin, is currently exploring whether body cooling during dives may help explain this phenomenon.

"Rebreathing had never been considered as a potential natural mechanism for underwater respiration in vertebrates," says Luke Mahler, an assistant professor in EEB at the University of Toronto and Boccia's thesis supervisor. "But our work shows that this is possible and that anoles have deployed this strategy repeatedly in species that use aquatic habitats."

Swierk and Mahler are planning future projects to better understand the evolution of the physiology and behavior related to rebreathing. "Anoles are a remarkable group of lizards, and the number of ways that this taxon has diversified to take advantage of their environments is mind-boggling," said Swierk.

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The paper, "Repeated evolution of underwater rebreathing in diving Anolis lizards," was published in Current Biology.

OOPS

Pu particles from nuclear testing more complex than previously thought

Plutonium particles from British nuclear testing in outback Australia more complex than previously thought, scientists warn

MONASH UNIVERSITY

Research News

 

More than 100 kg of highly toxic uranium (U) and plutonium (Pu) was dispersed in the form of tiny 'hot' radioactive particles after the British detonated nine atomic bombs in remote areas of South Australia, including Maralinga.

Scientists say that these radioactive particles persist in soils to this day, more than 60 years after the detonations. Previously, we had limited understanding of how Pu was released from these "hot" particles into the environment for uptake by wildlife around Maralinga.

But now, a new study published today in Scientific Reports and led by Monash University researchers warns that the particles are actually more complex and varied than previously thought. This means that the processes which slowly release Pu into the environment are also much more complex and varied.

"The British detonated nine nuclear bombs and conducted hundreds of nuclear tests in outback South Australia between 1953 and 1963," said lead study author Megan Cook, a PhD student from the Monash University School of Earth, Atmosphere and Environment. "The resulting radioactive contamination and cover-up continues to haunt us."

"The results of our study profoundly changes our understanding of the nature of hot particles at Maralinga - despite the fact that those were some of the best studied particles anywhere in the world," said study co-author Associate Professor Vanessa Wong.

The research team used synchrotron radiation at the Diamond Light Source near Oxford, UK to decipher the physical and chemical make-up of the particles.

At Monash University they dissected some of the hot particles using a nano-sized ion beam, and further characterised the complex make-up of these particles down to the nano-size in exquisite details.

The researchers demonstrated that the complexity of the hot particles arose from the cooling of polymetallic melts from thousands of degrees Celsius in the explosion cloud during their formation.

"We found that the particles contained low-valence plutonium-uranium-carbon compounds that are typically highly reactive, yet, had been stabilised in the hot-particle matrix for nearly 60 years," said corresponding author Dr Barbara Etschmann.

Between 1950 and 1988 alone there were more than 230 recorded nuclear weapon accidents, including at least 10 with documented release of radioactive particles into the environment. The risks of such incidents are only increasing as international treaties such as the Intermediate-Range Nuclear Forces Treaty were cancelled.

"Understanding the fate of hot particles in the unique setting of the Australian outback is critical for securing Australia in case of nuclear incidents in the region, and returning all the native land affected by the British tests to the traditional Anangu owners of the Maralinga Tjarutja lands," said study co-author Professor Joël Brugger.

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