Category: 7. Science

A new trans-Neptunian object, 2017 OF201, has been found with a vast orbit and potential dwarf planet size. The finding hints at more hidden bodies beyond Neptune.

A research team led by Sihao Cheng at the Institute for Advanced Study’s School of Natural Sciences has identified a remarkable trans-Neptunian object (TNO) at the far reaches of the solar system. The object has been designated 2017 OF201.

Based on its estimated size, 2017 OF₂₀₁ could meet the criteria for classification as a dwarf planet, placing it in the same category as Pluto. It is among the most distant objects ever observed in the solar system and indicates that the region beyond Neptune in the Kuiper Belt, long assumed to be nearly empty, may in fact harbor more bodies than expected.

Cheng, working with Princeton University collaborators Jiaxuan Li and Eritas Yang, detected the object using advanced computational techniques designed to reveal distinctive orbital patterns across the sky. The discovery was confirmed by the International Astronomical Union’s Minor Planet Center on May 21, 2025, and was also described in a preprint released on arXiv.

Trans-Neptunian objects are minor planets whose orbits lie, on average, farther from the Sun than Neptune’s. What makes 2017 OF₂₀₁ particularly noteworthy is both its extreme orbital characteristics and its unusually large size.

“The object’s aphelion—the farthest point on the orbit from the Sun—is more than 1600 times that of the Earth’s orbit,” explains Cheng. “Meanwhile, its perihelion—the closest point on its orbit to the Sun—is 44.5 times that of the Earth’s orbit, similar to Pluto’s orbit.”

Complex history of gravitational encounters

This extreme orbit, which takes the object approximately 25,000 years to complete, suggests a complex history of gravitational interactions. “It must have experienced close encounters with a giant planet, causing it to be ejected to a wide orbit,” says Yang. “There may have been more than one step in its migration. It’s possible that this object was first ejected to the Oort cloud, the most distant region in our solar system, which is home to many comets, and then sent back,” Cheng adds.

“Many extreme TNOs have orbits that appear to cluster in specific orientations, but 2017 OF₂₀₁ deviates from this,” says Li. This clustering has been interpreted as indirect evidence for the existence of another planet in the solar system, Planet X or Planet Nine, which could be gravitationally shepherding these objects into their observed patterns. The existence of 2017 OF₂₀₁ as an outlier to such clustering could potentially challenge this hypothesis.

Cheng and his team estimate that 2017 OF₂₀₁ is about 700 km in diameter, which would make it the second largest object discovered with such an extended orbit. For comparison, Pluto’s diameter is 2,377 km. The researchers note that further observations, possibly with radio telescopes, will be required to measure the object’s true size more precisely.

Identifying the object in telescope data

Cheng discovered the object as part of an ongoing research project to identify TNOs and possible new planets in the outer solar system. The object was identified by pinpointing bright spots in an astronomical image database from the Victor M. Blanco Telescope and Canada France Hawaii Telescope (CFHT), and trying to connect all possible groups of such spots that appeared to move across the sky in the way a single TNO might. This search was carried out using a computationally efficient algorithm produced by Cheng. Ultimately, they identified 2017 OF₂₀₁ in 19 different exposures, captured over 7 years.

The discovery has significant implications for our understanding of the outer solar system. The area beyond the Kuiper Belt, where the object is located, has previously been thought to be essentially empty, but the team’s discovery suggests that this is not so.

“2017 OF₂₀₁ spends only 1% of its orbital time close enough to us to be detectable. The presence of this single object suggests that there could be another hundred or so other objects with similar orbit and size; they are just too far away to be detectable now,” Cheng states. “Even though advances in telescopes have enabled us to explore distant parts of the universe, there is still a great deal to discover about our own solar system.”

The detection also demonstrates the power of open science. “All the data we used to identify and characterize this object are archival data that are available to anyone, not only professional astronomers,” says Li. “This means that groundbreaking discoveries aren’t limited to those with access to the world’s largest telescopes. Any researcher, student, or even citizen scientist with the right tools and knowledge could have made this discovery, highlighting the value of sharing scientific resources.”

Reference: “Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201” by Sihao Cheng, Jiaxuan Li and Eritas Yang, 21 May 2025, arXiv.
DOI: 10.48550/arXiv.2505.15806

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Life doesn’t always play by the tidy rules in textbooks. Most organisms use oxygen to produce ATP, which is energy used by cells. Some life forms, especially microbes, tap other chemicals when oxygen is scarce. The usual explanation says it’s one mode or the other.

A team studying a microbe from a Yellowstone hot spring found something different. This bacterium can use oxygen and sulfur at the same time to produce energy. That mixed strategy gives it an edge when oxygen levels fluctuate.

Lisa Keller of Montana State University is the lead author of this research that describes her work with bacterial samples from a group called Aquificales.

Along with her adviser and mentor Eric Boyd, professor in the College of Agriculture’s Department of Microbiology and Cell Biology, they published their fascinating work in the journal Nature Communications.

Microbes that breathe oxygen and sulfur

Respiration is how a cell converts food into usable energy (ATP). In oxygen-based respiration, cells move electrons through a chain of reactions and pass them to oxygen at the end.

Anaerobic respiration does a similar job but transfers electrons to other acceptors, such as sulfur, nitrate, or iron. Both strategies work; they are just different.

The hot-spring bacterium, Aquificales, challenged the usual either-or assumption. Under the right conditions, it kept both systems running.

That meant that while the bacteria were producing sulfide – an anaerobic process – they were using oxygen, meaning that both metabolisms were occurring.

“There’s no explanation other than that these cells are breathing oxygen at the same time that they are breathing elemental sulfur,” Keller said.

Keller explained that the bacterium’s ability to conduct both processes at once challenges our understanding of how microbes survive, especially in dynamic, low-oxygen environments such as hot springs. 

Oxygen and sulfur in hot springs

Hot springs are tough places to live. Temperatures run high. Minerals dissolve into the water. Gases bubble in and out.

Oxygen dissolves less in hot water than in cool water and escapes more easily, so levels change from moment to moment. In that kind of environment, a flexible energy strategy goes a long way.

The bacterium in this study thrives at high temperatures and feeds on simple molecules, including hydrogen gas. It can use oxygen when it’s available and elemental sulfur when oxygen dips.

How the study was done

Keller and her team isolated the microbe, then grew it in the lab at high temperatures with three ingredients: hydrogen gas as the energy source, elemental sulfur, and oxygen. They then tracked the cells’ chemical reactions and which genes were switched on.

Next, the team measured oxygen levels directly using gas chromatography. They also watched for the conversion of sulfur to sulfide, a clear sign of anaerobic sulfur respiration.

Gene expression data aligned with the chemistry: enzymes for both oxygen use and sulfur processing were active simultaneously.

Microbe’s oxygen-sulfur strategy

Cultures given hydrogen, sulfur, and oxygen grew faster and reached higher cell counts than cultures that had to use only oxygen or only sulfur.

That growth boost points to a simple payoff: more net energy when both pathways run together under low or unstable oxygen.

One detail matters for interpreting the results. The sulfide produced doesn’t persist in a mixed setup. Oxygen and certain metal ions in the broth can quickly consume it.

Without careful controls, that can hide the microbe’s dual strategy. This study accounted for that factor, which helps explain why this behavior may have been missed in past experiments.

Widespread pattern in nature

Genes and enzymes similar to those involved here are found in many microbes.

That suggests this hybrid mode could be more common than we realized, especially in places where conditions shift minute to minute. Hot springs and deep-sea vents contain fuels and oxidants that rise and fall.

Microbes that can keep multiple electron acceptors available may outgrow neighbors that wait for a single, ideal condition.

Flexibility like this also fits the story of early Earth. Oxygen didn’t flood the oceans all at once. It rose in patchy, inconsistent ways.

Microbes that could sense tiny amounts of oxygen while still relying on older, oxygen-free reactions likely had an advantage.

The results of this study may explain how ancient lifeforms adapted to the progressive oxygenation of Earth that began around 2.8 billion years ago – the Great Oxidation Event.

“This is really interesting, and it creates so many more questions,” Keller said. “We don’t know how widespread this is, but it opens the door for a lot of exploring.”

The Yellowstone bacterium isn’t ancient, but it shows a strategy that would have made sense when oxygen first began to matter.

How oxygen-sulfur combo works

Oxygen sits at the top of the energy ladder because it accepts electrons strongly, which usually means more energy per unit of fuel.

Sulfur compounds accept electrons too, though the energy yield is lower. When oxygen is scarce or fluctuating, using sulfur in parallel keeps the energy flowing rather than stalling.

Temperature and chemistry help set the stage. High heat speeds reactions and lowers oxygen solubility. Hydrogen gas, common around hydrothermal systems, supplies a steady stream of electrons.

Elemental sulfur is abundant in many volcanic and geothermal settings. Together, these conditions make simultaneous oxygen and sulfur respiration advantageous.

Real-world implications

Mixed respiration hints at new ways to run bioreactors and environmental cleanup efforts.

If microbes can be encouraged to keep more than one pathway active, engineers may squeeze extra efficiency from waste-to-energy systems, or keep pollutant breakdown steady when oxygen supply is uneven.

The same thinking applies to managing the sulfur and carbon cycles in complex settings where oxygen isn’t easy to control.

The work also urges careful experimental design. Testing a microbe in a strict “oxygen-only” or “no-oxygen” setup can miss behaviors that only appear when both are present.

Real environments rarely offer neat categories. Lab protocols that match those complex realities reveal strategies that would otherwise stay hidden.

To sum it all up, this heat-loving bacterium, Aquificales, broadens how we think about life’s energy playbook. It’s messy, adaptive, and full of clever workarounds that let microbes, and maybe eventually us, survive in a changing world.

The full study was published in the journal Nature Communications.

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Around 11,300 years ago, a massive star teetered on the precipice of annihilation. It pulsed with energy as it expelled its outer layers, shedding the material into space. Eventually it exploded as a supernova, and its remnant is one of the most studied supernova remnants (SNR). It’s called Cassiopeia A (Cas A) and new observations with the Chandra X-ray telescope are revealing more details about its demise.

Cas A’s progenitor star had between about 15 to 20 solar masses, though some estimates range as high as 30 solar masses. It was likely a red supergiant, though there’s debate about its nature and the path it followed to exploding as a supernova. Some astrophysicists think it may have been a Wolf-Rayet star.

In any case, it eventually exploded as a core-collapse supernova. Once it built up an iron core, the star could no longer support itself and exploded. The light from Cas A’s demise reached Earth around the 1660s.

There are no definitive records of observers seeing the supernova explosion in the sky, but astronomers have studied the Cas A SNR in great detail in modern times and across multiple wavelengths.

This is a composite false colour image of Cassiopeia A. It contains data from the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray telescope. Image Credit: NASA/JPL-Caltech

New research in The Astrophysical Journal explains Chandra’s new findings. It’s titled “Inhomogeneous Stellar Mixing in the Final Hours before the Cassiopeia A Supernova.” The lead author is Toshiki Sato of Meiji University in Japan.

“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” said lead author Sato in a press release. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”

One of the problems with studying supernovae is that their eventual explosions are what trigger our observations. A detailed understanding of the final moments before a supernova explodes is difficult to obtain. “In recent years, theorists have paid much attention to the final interior processes within massive stars, as they can be essential for revealing neutrino-driven supernova mechanisms and other potential transients of massive star collapse,” the authors write in their paper. “However, it is challenging to observe directly the last hours of a massive star before explosion, since it is the supernova event that triggers the start of intense observational study.”

The lead up to the SN explosion of a massive star involves the nucleosynthesis of increasingly heavy elements deeper into its interior. The surface layer is hydrogen, then helium is next, then carbon and even heavier elements under the outer layers. Eventually, the star creates iron. But iron is a barrier to this process, because while lighter elements release energy when they fuse, iron requires more energy to undergo further fusion. The iron builds up in the core, and once the core reaches about 1.4 solar masses, there’s not enough outward pressure to prevent collapse. Gravity wins, the core collapses, and the star explodes.

This high-definition image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) unveils intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded. Image Credit: NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGhent), Tea Temim (Princeton University)

Chandra’s observations, combined with modelling, are giving astrophysicists a look inside the star during its final moments before collapse.

“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon,” said co-author Kai Matsunaga of Kyoto University in Japan. “This is a violent event where the barrier between these two layers disappears.”

The results were two-fold. Silicon-rich material travelled outward, while neon-rich material travelled inward. This created inhomogeneous mixing of the elements, and small regions rich in silicon were found near small regions rich in neon.

Inhomogeneous elemental distribution in Cas A observed by Chandra. The difference in the mixing ratio of blue and green colors clearly shows the different composition in the O-rich ejecta. The red, green, and blue include emission within energy bands of 6.54–6.92 keV (Fe Heα), 1.76–1.94 keV (Si Heα), and 0.60–0.85 keV (O lines), respectively. The ejecta highlighted in red and green are products of explosive nucleosynthesis, while the ejecta in blue and emerald green reflect stellar nucleosynthesis. The circles in the small panels are O-rich regions used for spectral analysis. The regions of high and low X-ray intensity in the Si band are indicated by the magenta and cyan circles, respectively. Image Credit: Toshiki Sato et al 2025 ApJ 990 103

This is part of what the researchers call a ‘shell merger’. They say it’s the final phase of stellar activity. It’s an intense burning where the oxygen burning shell swallows the outer Carbon and Neon burning shell deep inside the star’s interior. This happens only moments before the star explodes as a supernova. “In the violent convective layer created by the shell merger, Ne, which is abundant in the stellar O-rich layer, is burned as it is pulled inward, and Si, which is synthesized inside, is transported outward,” the authors explain in their research.

This schematic shows the interior of a massive star in the process of a ‘shell merger.’ It shows both the downward plumes of Neon-rich material and the upward plumes of silicon-rich material. Image Credit: Toshiki Sato et al 2025 ApJ 990 103

The intermingled silicon-rich and neon-rich regions are evidence of this process. The authors explain that the the silicon and neon did not mix with the other elements either immediately before or immediately after the explosion. Though astrophysical models have predicted this, it’s never been observed before. “Our results provide the first observational evidence that the final stellar burning process rapidly alters the internal structure, leaving a pre-supernova asymmetry,” the researchers explain in their paper.

For decades, astrophysicists thought that SN explosions were symmetrical. Early observations supported the idea, and the basic idea behind core-collapse supernovae also supported symmetry. But this research changes the fundamental understanding of supernova explosions as asymmetrical. “The coexistence of compact ejecta regions in both the “O-/Ne-rich” and “O-/Si-rich” regimes implies that the merger did not fully homogenize the O-rich layer prior to collapse, leaving behind multiscale compositional inhomogeneities and asymmetric velocity fields,” the researchers write in their conclusion.

This asymmetry can also explain how the neutron stars left behind get their acceleration kick and lead to high-velocity neutron stars.

These final moments in a supernova’s life may also trigger the explosion itself, according to the authors. The turbulence created by the inner turmoil may have aided the star’s explosion.

“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” said co-author Hiroyuki Uchida also of Kyoto University. “Such final internal activity of a star may change its fate—whether it will shine as a supernova or not.”

“For a long time in the history of astronomy, it has been a dream to study the internal structure of stars,” the researchers write in their paper’s conclusion. This research has given astrophysicists a critical glimpse into a progenitor star’s final moments before explosion. “This moment not only has a significant impact on the fate of a star, but also creates a more asymmetric supernova explosion,” they conclude.

The Dreams of Small Animals
ArtYard
June 21–October 5, 2025
Frenchtown, NJ

Can we learn to perceive as other beings do? Can we even learn to perceive other beings at all—not as objects of knowledge, but emissaries of worlds beyond our grasp? In The Dreams of Small Animals, Ash Eliza Williams probes metaphysical boundaries in paintings that channel the sensory perceptions of flowers, frogs, bugs, and birds. Williams uses multi-panel compositions that recall the sequential logic of a storyboard, but rather than translating the nonhuman into a legible narrative, they render their subjects more mystical in works where the boundaries between subject and environment become porous, vibrational.

The erotic The Dreams of a Dandelion (2024) is an eighty-three-panel sequence filled with ambiguous clefts, hairy mounds, and proboscises entering slits, realized in a citric orange that makes you salivate a little. The painting reminds you that a flower is a genital organ—its pollination a multispecies coitus—and effectively suggests an organism that does not perceive by seeing, but by touching. And yet, eyes make a distinctive appearance here, as exaggerated pictograms on the wings of descending butterflies. Many lepidopterans have developed striking eye-like spots, but a flower cannot “see” them—or can it? Perhaps it feels the touch of their gaze. Williams’s work does not approximate the physical sensorium of a dandelion as much as it speaks to perception itself as a super-sensory and spectral realm of encounter.

Have you ever stared at a bug and felt it looking back? Most arthropods have sophisticated sight, and the misconception that their compound eyes provide a “low-resolution” optical system says more about the limits of human perception, with its fixation upon the image. Our own eyes are essentially a stereoscopic camera, but an arthropod perceives space, light, and motion in ways we cannot fathom. Dragonflies are thought to process up to ten times more visual information, encompassing colors and wavelengths that are invisible to humans. Bees see ultraviolet light, and use it to read a hidden language of flowers.

Williams’s exhibition provokes unique speculations on how perception is limited by our body schema, anatomically engrained and culturally reinforced. Human cosmologies have often gravitated toward four-fold scales of space and time: four directions, four elements, four seasons. As animals with four limbs, quadruple poetics may feel most comfortable to us. How would we perceive the manifold poetry of a creature with fifteen pairs of legs, like a house centipede, whose very presence makes many humans uncomfortable?

Giant impact structures, including the potential remains of ancient “protoplanets,” may be lurking deep beneath the surface of Mars, new research hints. The mysterious lumps, which have been perfectly preserved within the Red Planet’s immobile innards for billions of years, may date back to the beginning of the solar system.

In a new study, published Aug. 28 in the journal Science, researchers analyzed “Marsquake” data collected by NASA’s InSight lander, which monitored tremors beneath the Martian surface from 2018 until 2022, when it met an untimely demise from dust blocking its solar panels. By looking at how these Marsquakes vibrated through the Red Planet’s unmoving mantle, the team discovered several never-before-seen blobs that were much denser than the surrounding material.

Animals

Gt(ROSA)26Sor^{tm14(CAGtdTomato)Hze} (Ai14, #007908), Cx3cr1^tm1Litt/J (#005582), Cx3cr1^{tm1.1(cre)Jung} (#025524), Gt(ROSA)26Sor^{tm32(CAG-COP4*H134R/EYFP)Hze} conditional allele (Ai32, #012569) and Csf1r^tm1.2Jwp (#021212) mice were obtained from the Jackson Laboratory. Hoxb8^IRES-Cre and Hoxb8^X-IRES-Cre mice were generated in our laboratory and reported by [11] and [9], respectively. Briefly, Hoxb8^X-IRES-Cre homozygous mutant mice contain an X-IRES-Cre allele at the Hoxb8 locus. The X-IRES-Cre allele was generated by replacing six amino acids in the homeobox DNA-binding domain with five alanines and glutamic acid. These mice exhibit the typical pathological grooming behavior originally reported [28]. Csf1r^∆FIRE mice were generated in our laboratory (details below), replicating the Csf1r^∆FIRE mouse line initially reported in [20].

Generation of Csf1r
^∆FIRE mutant mice

Csf1r^∆FIRE mutant mice were generated by pronuclear injection with gRNA1(20 ng/µl) and gRNA2 (20 ng/µl) and Cas9 protein (20 ng/µl) in C57BL6/J zygotes. gRNA1 sequence: 5′-GACTTGCGGGGTCAGCAAAC-3′ and gRNA1 sequence: 5′-AGCCCCCAATGAGTCTGTAC-3′. Founders were crossed to C57BL6/J, and their offspring were backcrossed to C57BL6/J mice for at least five times before initiation of experiments.

Flow cytometry cell sorting and analysis

Hematopoietic progenitor isolation and cell sorting

Embryo isolation and dissection were performed as previously described [5, 6]. Fetal livers were dissected from E12.5 embryos and placed on ice in 5% fetal bovine serum (FBS, Atlanta Biologicals) in 1X Hanks’ balanced salt solution (HBSS, Gibco). Fetal liver tissue was pooled according to their respective genotype (i.e., Hoxb8 WT: Cx3cr1^GFP/+; Hoxb8^IRES-Cre/+; Rosa26^{CAG-LSL-tdTomato/+} or Hoxb8^IRES-Cre/+; Rosa26^{CAG-LSL-tdTomato/+}, Hoxb8 conditional mutant: Hoxb8^{X-IRES-Cre/conditional}; Rosa26^{CAG-LSL-tdTomato/+}), then gently dissociated mechanically. Cells were passed through an 80 µm cell strainer to obtain a single-cell suspension.

Anti-mouse antibodies used consisted of the following: TER-119 PerCP-Cy5.5 (1:50, BioLegend, #116228) and c-Kit PE-Cy7 (1:100, Biolegend, #105814) in 5% FBS/1% BSA/1X HBSS. Cells were incubated with their respective antibody cocktail for 30 min on ice. Cells were counter-stained with 3 µM DAPI in 1X HBSS. WT and conditional mutant Hoxb8 hematopoietic progenitors were defined with the immunophenotype signature of DAPI^– Ter119^– kit^hi tdTomato⁺ GFP^+/- or DAPI^– Ter119^– kit^hi tdTomato⁺. Sorted WT and conditional mutant Hoxb8 hematopoietic progenitors were collected in sterile 1X HBSS media before transplantation. Flow cytometry data were obtained using the BD Bioscience FACS ARIA flow cytometry sorter. All FACS data were analyzed with FlowJo_v10.8.1 (Celeza GmbH).

Neonatal microglia cell isolation and cell sorting

Brains of neonatal mice were harvested and processed using the Brain Dissociation Kit for mouse and rat (#130-107-677, Miltenyi Biotec). Briefly, brains were dissected from P0–P4 mice and placed on ice in Dulbecco’s phosphate-buffered saline (DPBS, Gibco). Brains were from mice of the following genotypes (Hoxb8 WT: Hoxb8^IRES-Cre/+; Rosa26^{CAG-LSL-tdTomato/+} or Cx3cr1^GFP/+; Hoxb8^IRES-Cre/+; Rosa26^{CAG-LSL-tdTomato/+}). Neonatal brains were then enzymatically and mechanically dissociated using the gentleMACS^TM Octo Dissociator with Heaters (#130-096-427, Miltenyi Biotec) for 30 min at 37 °C. Cells were passed through a 70 µm cell strainer to obtain a single-cell suspension, followed by debris removal and red blood cell lysis steps. To minimize background signal and false positive signals in our cell sorting procedure, cells were resuspended in Fc block (1:2000, purified CD16/32, Biolegend, #101302) in 5% FBS/1X HBSS for 10 min, 4 °C before cell antibody staining.

Anti-mouse or anti-mouse/human antibodies used consisted of the following: CD45 APC (1:160, Biolegend, #103112) and CD11b Alexa Fluor^TM 700 (1:160, Biolegend, #101222) in 5% FBS/1% BSA/1X HBSS. Cells were incubated with their respective antibody cocktail for 30 min on ice. Cells were counter-stained with 3 µM DAPI in 1X HBSS. Hoxb8 microglia (DAPI^– CD45^lo CD11b^hi tdTomato⁺ or DAPI^– CD45^lo CD11b^hi tdTomato⁺ GFP⁺) and non-Hoxb8 microglia (DAPI^– CD45^lo CD11b^hi tdTomato^– or DAPI^– CD45^lo CD11b^hi tdTomato^– GFP⁺) were sorted from the WT Hoxb8 backgrounds. Sorted microglial cells were collected in sterile 1X HBSS media before transplantation. Flow cytometry data were obtained using the BD Bioscience FACS ARIA flow cytometry sorter. All FACS data were analyzed with FlowJo_v10.8.1 (Celeza GmbH).

Csf1r
^∆FIRE microglia isolation and flow cytometry analysis

Microglia isolation was performed as previously described [29]. Briefly, mice were euthanized by isoflurane and perfused with ice-cold 1X HBSS. Mouse brains were homogenized in a 15 mL Dounce homogenizer containing a digestion cocktail of 0.05% Collagenase D (Sigma), 0.1 µg/mL TLCK (Sigma), 0.025 U/mL DNase I (Sigma), and 0.5% Dispase (Roche), then digested at room temperature for 15 min. After centrifugation, cell pellets were resuspended in 5 mL of 30% Percoll/1X HBSS, overlaid with 5 mL 1X HBSS. The 70–30% interphase was collected and washed with 1X HBSS. The cell pellet was resuspended in 10% FBS/1X HBSS for flow cytometry analysis. Cells were stained with CD45 PE (1:100, Biolegend, #147711) and CD11b APC (1:100, Biolegend, #101212) in 1X HBSS on ice for 30 min. Cells were counter-stained with 3 µM DAPI in 1X HBSS. Flow cytometry data were obtained using the BD Bioscience FACSCanto II flow cytometry analyzer. All FACS data were analyzed with FlowJo_v10.8.1 (Celeza GmbH).

Intra-cerebral transplantations

Hematopoietic progenitors

freshly sorted WT or conditional mutant Hoxb8 hematopoietic progenitors (~2.5 × 10⁴ DAPI^– TER119^– kit^hi tdTomato⁺ cells/2–3 µL) or sterile 1X HBSS (sham controls) were transplanted bilaterally into the frontal hemispheres of P1–P4 Cx3cr1^Cre/+; Csf1r^fl/+ and Cx3cr1^Cre/+; Csf1r^fl/Δ recipient mice.

Neonatal microglia

freshly sorted WT Hoxb8 (~2.5 × 10⁴ DAPI^– CD45^lo CD11b^hi tdTomato⁺ or DAPI^– CD45^lo CD11b^hi tdTomato⁺ GFP⁺ cells/2–3 µL) and WT non-Hoxb8 microglia (~2.5 × 10⁴ DAPI^– CD45^lo CD11b^hi tdTomato^– or DAPI^– CD45^lo CD11b^hi tdTomato^– GFP⁺ cells/2–3 µL) or sterile 1X HBSS (sham controls) were transplanted bilaterally into the frontal hemispheres of P1–P4 Csf1r^∆FIRE/+ and Csf1r^{∆FIRE/∆FIRE} recipient mice. For co-transplantation, freshly sorted WT Hoxb8 (~2.5 × 10⁴ DAPI^– CD45^lo CD11b^hi tdTomato⁺ GFP⁺ cells/2–3 µL) and WT non-Hoxb8 microglia (~2.5 × 10⁴ DAPI^– CD45^lo CD11b^hi tdTomato^– GFP⁺ cells/2–3 µL) were mixed at the physiological equivalent of 70:30 WT non-Hoxb8:WT Hoxb8 microglia before bilateral transplantation into the frontal hemispheres of P1–P4 Csf1r^{∆FIRE/∆FIRE} recipient mice. As controls, blind injections of total microglia (~2.5 × 10⁴ DAPI^– CD45^lo CD11b^hi tdTomato^+/- GFP^+/- cells/2–3 µL), irrespective of lineage, were bilaterally transplanted in the same manner.

Cryosectioning and immunofluorescence

Postnatal brain tissue was processed and sectioned as previously described by [5]. For immunofluorescence, brain samples were briefly permeabilized with 0.2% Triton X-100, and 1% Sodium deoxycholate solution, then incubated overnight with a primary antibody mixture at 4 °C. The following day the sections were incubated with secondary antibodies for 2 h at room temperature. Sections were counter-stained with DAPI (D1306, Molecular Probes) and mounted with ProLong^TM Diamond Antifade Mountant (P36961, Invitrogen) and microscope cover glass (1419-10, Globe Scientific). Images were acquired on the Leica TCS SP5 confocal microscope and processed and analyzed using Imaris x64 8.0.2 (Bitplane), as described below.

Primary antibodies used: chicken anti-GFP (1:500, GFP-1020, Aves Labs), guinea pig anti-tdTomato-GP-Af430 (1:250, Frontier Institute, AB_2631185), anti-rabbit Iba1 (1:500, Wako, 019-19741), rabbit anti-mouse Tmem119 (1:500, 209064, Abcam), rat anti-P2RY12 (1:200, Biolegend, 848002), and rat anti-mouse CD206 Alexa Fluor 647 (1:200, Biolegend, 141712). Secondary antibodies used: goat anti-chicken Alexa Fluor 488 (1:500, A-11039, Thermo Fisher Scientific), goat anti-guinea pig Alexa Fluor^TM 555 (1:500, A-21428, Thermo Fisher Scientifc,), goat anti-rabbit Alexa Fluor^TM 647 (1:500, A-21245, Thermo Fisher Scientific), and goat anti-rat Alexa Fluor 647^TM (1:500, A-48265, Thermo Fisher Scientific). Both the primary and secondary antibodies that we have used have been tested for specificity and cross-reactivity.

Surgery implantation and housing

All survival surgeries were performed under aseptic conditions under stereotaxic equipment (Kopf instruments). Mice were anaesthetized using 4.0% isoflurane during induction and maintained at 1.5% throughout the surgical procedure. All surgically implanted mice were housed in individual cages till the end of the experiment. All stereotactic coordinates are in relation to bregma in mm. All mice received unilateral implantation of cannula (PlasticsOne, Roanoke, VA) for the brain region dorsomedial prefrontal cortex (dmPFC). Cannulas were implanted at the following stereotaxic coordinate: mPFC (+1.9 AP, 0.4 ML, −2.0 DV).

Optogenetic stimulation

For optical stimulation common to all behavioral experiments, multimode optical fiber (NA 0.37; 200 μm core; Thorlabs, Newton, NJ) was connected to a 473 nm light source through an FC/PC adapter. The free end of the fiber was connected to the implanted cannula before the initiation of the experiment. Following the experiment, the optic fiber was gently removed and a dust cap was secured on the cannula. The mice were kept back in the home cage to recover from the optogenetic stimulation.

Optogenetic induction of grooming behavior

All grooming behaviors in the experiments were measured by 6 min of video recordings with 2 min of each baseline, optogenetic stimulation and post stimulation condition within the home cage. The home cage environment was chosen for recording in order to ensure that other environmental factors do not affect the experimental outcome. Each experimental subject was pre-conditioned with optic fiber for 5 min before the experiment started. Laser power for the experimental and control subjects ranged between 2.8–7.6 mW for mPFC brain regions. The same laser powers were used to test control versus experimental subjects for the behavioral output. The laser power reported represents the power emerging from the laser light source. After each recording session, the optic fiber was carefully removed until the next experimental session. From the recorded videos, the behavioral phases of grooming were classified into phase III and phase IV if the experimental subject displayed facial grooming (phase III) or body grooming (phase IV). Each individual grooming bout corresponding to phase III and phase IV was scored for every experiment performed within the pre, during and post stimulation conditions for each experimental and control subject for every genotype tested. The latency or the onset of grooming was measured based on the first occurrence of phase III or phase IV grooming bout in response to optogenetic stimulation.

Confocal microscopy

Images were acquired on a Leica TCS SP5 confocal system. Brain sections were imaged for image acquisition with a 10X (0.4 NA, Leica) or 20X objective (0.4 NA, Leica) and 1.0X, 2.0X, or 5X digital zoom. Images were acquired at a 512 × 512 or 1024 × 1024 resolution and 200 or 400 Hz scan speed, using a 2.0 or 5.0 µm z-depth through the tissue.

Imaris image analysis

Images were processed using Imaris Image Analysis Software x64 (v8.0.2, Bitplane). The ‘Spots’ function counted the number of microglia per unit area (mm²). The diameter of the cell soma was set at 15 µm. To further identify the subsets of cells that co-label with Iba1, the spots were filtered using the ‘mean intensities’ of the fluorescence of the marker. The ‘Surface’ function was used to quantify the area of the analysis region.

Behavioral testing and analysis

All behavioral tests were performed between 6:30–10:00 pm, 30 min after the transition from light to dark phase, which begins at 6 pm. Mice were habituated to the behavioral room for 30 min under 0–5 Lux prior to testing acquisition. All tested mice were between 3–5-months-old.

Grooming test

The LABORAS behavioral assay (Metris B.V.) is a fully automated system that monitors specific mouse behaviors based on vibration (e.g., grooming, itching, locomotion, eating, drinking, and rest) and has been used in our laboratory [13]. Briefly, a single mouse is tested per cage and allowed to move freely while the software records the vibrations of their motions and assigns them to distinct behaviors. Illumination was at 0 Lux. To score behavioral phenotypes, mice underwent a two-hour trial once.

Light/dark box

The test apparatus consisted of a box (40 × 40 × 35 cm) divided into a dark, enclosed chamber and an open, brightly illuminated chamber. Illumination was at 600 Lux. To begin testing acquisition, a mouse was placed into the dark chamber (facing the transition opening) and allowed to move freely between the two chambers for 5 min. The total time spent in both chambers was analyzed. To score behavioral phenotypes, mice underwent a 5-min trial once. Animal movement was tracked using AnyMaze software.

Elevated plus maze

The apparatus consisted of four arms that were elevated ~50 cm from the ground: two enclosed by walls and the other with no walls. Illumination was at 100 Lux. Each mouse was acclimatized for 30 min in the testing room. To begin testing acquisition, each mouse was placed at the junction of the four arms with the mouse facing an open arm and allowed to move freely for 5 min as described by [30]. Duration in each arm was recorded by AnyMaze video-tracking software.

Statistical analysis

Data from all experiments were analyzed with GraphPad Prism software v10.0.1 (San Diego, CA). Unpaired t-tests were used for direct comparison between 2 data groups. Standard one-way and two-way ANOVA followed by post hoc analysis using Tukey’s multiple comparisons tests was used to compare multiple data groups. All data are graphically reported as mean ± sem. A P value < 0.05 was considered significant.

Ethics approval

All methods and experiments in this study have been performed on mice. Experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Utah, Public Health Service Assurance #D16-00018 (A3031-01).

Scientists studying samples from the asteroid Bennu have found that it contains a remarkable mix of materials — some of which formed long before the sun even existed.

Taken together, the findings, described in a trio of recently published papers, show how Bennu has preserved clues about the earliest days of our solar system.

Arthropod appendages are specialized for diverse roles including feeding, walking, and mating. Fossils from the Cambrian period (539 to 487 million years ago) preserve exceptional details of extinct arthropod appendages that can illuminate their anatomy and ecology. However, fossils are typically limited by small sample sizes or incomplete preservation, and thus functional studies of the appendages usually rely on idealized reconstructions. In new research, paleontologists focused on Olenoides serratus, a particularly abundant trilobite species in the Cambrian Burgess Shale that is unique among trilobites owing to the availability of numerous specimens with soft tissue preservation that allow us to quantify its appendages’ functional morphology.

The Burgess Shale in British Columbia, Canada, is renowned for its exceptional preservation of soft tissues in fossils, including limbs and guts.

While trilobites are abundant in the fossil record thanks to their hard exoskeleton, their soft limbs are rarely preserved and poorly understood.

The trilobite species Olenoides serratus offers a unique opportunity to study these appendages.

Harvard University paleontologist Sarah Losso and her colleagues analyzed 156 limbs from 28 fossil specimens of Olenoides serratus to reconstruct the precise movement and function of these ancient arthropod appendages, shedding light on one of the planet’s earliest and most successful animals.

“Understanding behavior and movement of fossils is challenging, because you cannot observe this activity like in living animals,” Dr. Losso said.

“Instead, we had to rely on carefully examining the morphology in as many specimens as possible, as well as using modern analogues to understand how these ancient animals lived.”

The researchers also measured the range of motion of the legs in the living horseshoe crab species Limulus polyphemus.

“Arthropods have jointed legs composed of multiple segments that can reach upwards (extend) or downwards (flex),” they said.

“The range of motion depends on the difference between how far each joint can reach in either direction.”

“This range, along with the leg and shape of each segment, determines how the animal uses the limb for walking, grabbing, and burrowing.”

“Horseshoe crabs, common arthropods found along the eastern shore of North America, are frequently compared to trilobites even though they are not closely related.”

“Horseshoe crabs belong to a different branch of the arthropod tree, more closely related to spiders and scorpions, whereas trilobites’ family ties remain uncertain.”

“The comparison is due to the similarity in that both animals patrol the ocean floor on jointed legs.”

“The results, however, showed less similarity between the two animals.”

Unlike horseshoe crabs, whose limb joints alternate in their specialization for flexing and extending — a pattern that facilitates both feeding and protection — Olenoides serratus displayed a simpler, but highly functional limb design.

“We found that the limbs of Olenoides serratus had a smaller range of extension and only in the part of the limb farther from the body,” Dr. Losso said.

“Although their limbs were not used in exactly the same way as horseshoe crabs, Olenoides serratus could walk, burrow, bring food towards its mouth, and even raise its body above the seafloor.”

To bring their findings to life, the scientists created sophisticated 3D digital models based on hundreds of fossil images preserved at different angles.

Because fossilized trilobite limbs are usually squashed flat, reconstructing them in three-dimensions posed a challenge.

“We relied on exceptionally well-preserved specimens, comparing limb preservation across many angles and filling in missing details using related fossils,” said Harvard University’s Professor Javier Ortega-Hernández.

The team compared the shape of trace fossils with the movement of the limbs.

“Olenoides serratus could create trace fossils of different depths using different movements,” Dr. Losso explained.

“They could raise their body above the sediment in order to walk over obstacles or to move more efficiently in fast-flowing water.”

“Surprisingly, we discovered that the male species also had specialized appendages used for mating, and that each leg also had a gill used for breathing.”

The results were published on August 4, 2025 in the journal BMC Biology.

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S.R. Losso et al. 2025. Quantification of leg mobility in the Burgess Shale Olenoides serratus indicates functional differences between trilobite and xiphosuran appendages. BMC Biol 23, 238; doi: 10.1186/s12915-025-02335-3

As the Northern Hemisphere prepares for the autumnal equinox on September 22 and pumpkin-flavoured treats return in full force, the night sky is also offering a seasonal spectacle for skywatchers.

NASA says early risers on September 19 will be treated to a striking celestial trio just before sunrise. In the eastern sky, the Moon will appear closely aligned with Venus and Regulus, one of the brightest stars in the night sky. This rare conjunction offers a beautiful visual for both seasoned astronomers and casual skywatchers alike.

Later in the month, on September 21, Saturn will take center stage as Earth moves directly between Saturn and the Sun, During this time, Saturn will be at its closest and brightest point of the year. According to NASA, the planet’s iconic rings will be visible with just a small telescope, making this an ideal opportunity for backyard astronomers to get a clear view.

“Aside from the autumnal equinox in the Northern Hemisphere on Sept. 22 and the increase of pumpkin-flavored treats, September offers some celestial sights to enjoy. Just before sunrise on Sept. 19, you can catch a glimpse of a celestial trio. In the eastern skies, you will find the Moon cozied up to Venus and Regulus, one of the brightest stars in the sky,” NASA said.

It added, “A few days later on Sept. 21, Earth will position itself directly between Saturn and the Sun, meaning that Saturn will be at its closest and brightest all year. If you want to see its rings, all you will need is a small telescope.”

Here’s how you can watch Conjunction trio and Saturn at Opposition

According to NASA, the planet’s iconic rings will be visible with just a small telescope, making this an ideal opportunity for backyard astronomers to get a clear view.

“If you look to the east just before sunrise on September 19, you’ll see a trio of celestial objects in a magnificent conjunction. In the early pre-dawn hours, look east toward the waning, crescent Moon setting in the sky and you’ll notice something peculiar. The Moon will be nestled up right next to both Venus and Regulus, one of the brightest stars in the night sky,” NASA said.

It further mentioned, “The three are part of a conjunction, which simply means that they look close together in the sky (even if they’re actually far apart in space). To find this conjunction, just look to the Moon. And if you want some additional astronomical context, or want to specifically locate Regulus, this star lies within the constellation Leo, the lion.”

“Saturn will be putting on an out-of-this-world performance this month. Saturn will be visible with just your eyes in the night sky, but with a small telescope, you might be able to see its rings!” it added.