The fate of highly volatile elements (H, C, F, Cl and S) during planetary accretion and differentiation is debated. Recent analyses of water in non-carbonaceous chondrites (RC, OC, EC) and achondrites (angrites, eucrites) have been used to argue that inner solar system parent bodies accreted and retained their highly volatile element budgets from their primary feedstock without substantial loss during accretion, metamorphism and differentiation. An alternative model posits that differentiated inner solar system parent bodies (e.g., the angrite parent body, 4 Vesta, Earth) derived the majority of their water from a carbonaceous chondrite-like source, delivered during the final stages of accretion.In order to add new constraints to this debate, we have measured water in nominally anhydrous minerals, melt inclusions, and interstitial glass in ureilites, the largest group of primitive achondrites in the terrestrial meteorite collection. Primitive achondrites did not experience global melting and homogenization. Therefore, these meteorites capture part of the transition from chondritic to achondritic parent bodies, allowing us to constrain the fate of water during the earliest stages of differentiation. Our nano-scale secondary ion mass spectrometry (nanoSIMS) analyses allow us to assess the viability of ureilite-like material as a potential source of terrestrial water. Analyses of pigeonite in main group ureilites yield a range of 2.0 - 6.0 lg/g H2O, and analyses of high-Ca pyroxene and glass (glassy melt inclusions and interstitial glass) in the Almahata Sitta ureilitic trachyandesite yield ranges of 13 - 19 lg/g H2O and 44 - 216 lg/g H2O, respectively. Mass balance, incremental melting, and batch melting calculations yield a preferred ureilite parent body H2O content of 2 - 20 lg/g, similar to previous estimates of water in the eucrite parent body (4 Vesta), but lower than estimates of Earth's water budget. With these data, we demonstrate that 1) the ureilite parent body is H2O-depleted relative to the Earth; 2) ureilite-like material is unlikely to be a primary source of H2O to the Earth; 3) C and H are not necessarily coupled elements during planetary accretion and thermal processing; and 4) accretion, heating, partial melting, and degassing of rocky planetesimals likely results in significant depletion of H2O.& COPY; 2022 Elsevier Ltd. All rights reserved.

High-resolution imaging of galaxies in rest-frame UV has revealed the existence of giant star-forming clumps prevalent in high-redshift galaxies. Studying these substructures provides important information about their formation and evolution and informs theoretical galaxy evolution models. We present a new method to identify clumps in galaxies' high-resolution rest-frame UV images. Using imaging data from CANDELS and UVCANDELS, we identify star-forming clumps in an HST/F160W <= 25 AB mag sample of 6767 galaxies at 0.5 <= z <= 3 in four fields, GOODS-N, GOODS-S, EGS, and COSMOS. We use a low-passband filter in Fourier space to reconstruct the background image of a galaxy and detect small-scale features (clumps) on the background-subtracted image. Clumpy galaxies are defined as those having at least one off-center clump that contributes a minimum of 10% of the galaxy's total rest-frame UV flux. We measure the fraction of clumpy galaxies (f(clumpy)) as a function of stellar mass, redshift, and galaxy environment. Our results indicate that f(clumpy) increases with redshift, reaching similar to 65% at z similar to 1.5. We also find that fclumpy in low-mass galaxies (9.5 <= log (M*/M circle dot) <= 10) is 10% higher compared to that of their high-mass counterparts (log M*/M circle dot) > 10.5). Moreover, we find no evidence of significant environmental dependence of f(clumpy) for galaxies at the redshift range of this study. Our results suggest that the fragmentation of gas clouds under violent disk instability remains the primary driving mechanism for clump formation, and incidents common in dense environments, such as mergers, are not the dominant processes.

The Earth's core formation mechanism determines the siderophile and light elements abundance in the Earth's mantle and core. Previous studies suggest that the sink of massive liquid metal through a solid silicate mantle resulted in an unequilibrated core and the lower mantle. Here, we show that percolation can be an effective core formation mechanism in a convective mantle and modify the compositions of the lower mantle and the core through partial equilibration between them. This grain-scale metal flow has a high velocity to meet the time constraint of core formation. The Earth's core could have been enriched with light elements, and the abundance of the moderately siderophile elements in the mantle could have been elevated to the current value during this process. The trapped core-forming melt in the mantle during the stress-induced percolation can also explain the highly siderophile element abundance in the Earth's mantle.

Heterotopic ossification (HO) is a pathological process resulting in aberrant bone formation and often involves synovial lined tissues. During this process, mesenchymal progenitor cells undergo endochondral ossification. Nonetheless, the specific cell phenotypes and mechanisms driving this process are not well understood, in part due to the high degree of heterogeneity of the progenitor cells involved. Here, using a combination of lineage tracing and single-cell RNA sequencing (scRNA-seq), we investigated the extent to which synovial/tendon sheath progenitor cells contribute to heterotopic bone formation. For this purpose, Tppp3 (tubulin polymerization-promoting protein family member 3)-inducible reporter mice were used in combination with either Scx (Scleraxis) or Pdgfra (platelet derived growth factor receptor alpha) reporter mice. Both tendon injury- and arthroplasty-induced mouse experimental HO models were utilized. ScRNA-seq of tendon-associated traumatic HO suggested that Tppp3 is an early progenitor cell marker for either tendon or osteochondral cells. Upon HO induction, Tppp3 reporter(+) cells expanded in number and partially contributed to cartilage and bone formation in either tendon- or joint-associated HO. In double reporter animals, both Pdgfra(+)Tppp3(+) and Pdgfra(+)Tppp3(-) progenitor cells gave rise to HO-associated cartilage. Finally, analysis of human samples showed a substantial population of TPPP3-expressing cells overlapping with osteogenic markers in areas of heterotopic bone. Overall, these data demonstrate that synovial/tendon sheath progenitor cells undergo aberrant osteochondral differentiation and contribute to HO after trauma.

The symbiosis between cnidarians and dinoflagellates underpins the success of reef-building corals in otherwise nutrient-poor habitats. Alterations to symbiotic state can perturb metabolic homeostasis and thus alter the release of biogenic volatile organic compounds (BVOCs). While BVOCs can play important roles in metabolic regulation and signalling, how the symbiotic state affects BVOC output remains unexplored. We therefore characterised the suite of BVOCs that comprise the volatilome of the sea anemone Exaiptasia diaphana ('Aiptasia') when aposymbiotic and in symbiosis with either its native dinoflagellate symbiont Breviolum minutum or the non-native symbiont Durusdinium trenchii. In parallel, the bacterial community structure in these different symbiotic states was fully characterised to resolve the holobiont microbiome. Based on rRNA analyses, 147 unique amplicon sequence variants (ASVs) were observed across symbiotic states. Furthermore, the microbiomes were distinct across the different symbiotic states: bacteria in the family Vibrionaceae were the most abundant in aposymbiotic anemones; those in the family Crocinitomicaceae were the most abundant in anemones symbiotic with D. trenchii; and anemones symbiotic with B. minutum had the highest proportion of low-abundance ASVs. Across these different holobionts, 142 BVOCs were detected and classified into 17 groups based on their chemical structure, with BVOCs containing multiple functional groups being the most abundant. Isoprene was detected in higher abundance when anemones hosted their native symbiont, and dimethyl sulphide was detected in higher abundance in the volatilome of both Aiptasia-Symbiodiniaceae combinations relative to aposymbiotic anemones. The volatilomes of aposymbiotic anemones and anemones symbiotic with B. minutum were distinct, while the volatilome of anemones symbiotic with D. trenchii overlapped both of the others. Collectively, our results are consistent with previous reports that D. trenchii produces a metabolically sub-optimal symbiosis with Aiptasia, and add to our understanding of how symbiotic cnidarians, including corals, may respond to climate change should they acquire novel dinoflagellate partners.

The CO2-concentrating mechanism (CCM) used by eukaryotic algae represents an inorganic carbon pump [Ci: bicarbonate (HCO3-), carbon dioxide (CO2), and carbonic acid (CO32-)] that generates an elevated concentration of CO2 around Rubisco, which promotes carbon fixation. This mechanism, which evolved independently several times, has the potential to be transferred (at least some key activities) into crop species, which could boost agricultural yields and contribute to sustaining a growing world population. One component of the CCM of the unicellular green alga Chlamydomonas reinhardtii is the putative chloroplast envelope bicarbonate channel, LCIA. In their study, Forster et al. (2023) have exploited heterologous systems defective for concentrating Ci to provide strong evidence that LCIA functions as a channel that facilitates bicarbonate movement into the plastid stroma.

Elucidating biological processes has relied on the establishment of model organisms, many of which offer advantageous features such as rapid axenic growth, extensive knowledge of their physiological features and gene content, and the ease with which they can be genetically manipulated. The unicellular green alga Chlamydomonas reinhardtii has been an exemplary model that has enabled many scientific breakthroughs over the decades, especially in the fields of photosynthesis, cilia function and biogenesis, and the acclimation of photosynthetic organisms to their environment. Here, we discuss recent molecular/technological advances that have been applied to C. reinhardtii and how they have further fostered its development as a "flagship" algal system. We also explore the future promise of this alga in leveraging advances in the fields of genomics, proteomics, imaging, and synthetic biology for addressing critical future biological issues.

We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity ( RV) measurements constrain the mass to be 9.67(-0.82)(+0.83) M-circle plus. We also report the discovery of an additional planet candidate on an outer orbit that is most likely nontransiting. The possible periods of the planet candidate are approximately 20-63 days, with the corresponding RV semiamplitudes expected to range from 3.2 to 5.4 m s(-1) and minimum masses from 12.6 to 31.1 M-circle plus. The radius of the transiting planet (planet b) is 1.93(-0.09)(+0.11) R-circle plus, which results in a mean density of 7.4(-1.2)(+1.4) g cm(-3) suggesting that TOI-784 b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784 b is located at the lower edge of the so-called "radius valley" in the radius versus insolation plane, which is consistent with the photoevaporation or core-powered mass-loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are 88.60(-0.86)(+0.84) and <= 88 degrees.3-89 degrees.2, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.

Climatic extreme events are expected to occur more frequently in the future, increasing the likelihood of unprecedented climate extremes (UCEs) or record-breaking events. UCEs, such as extreme heatwaves and droughts, substantially affect ecosystem stability and carbon cycling by increasing plant mortality and delaying ecosystem recovery. Quantitative knowledge of such effects is limited due to the paucity of experiments focusing on extreme climatic events beyond the range of historical experience. Here, we present a road map of how dynamic vegetation demographic models (VDMs) can be used to investigate hypotheses surrounding ecosystem responses to one type of UCE: unprecedented droughts. As a result of nonlinear ecosystem responses to UCEs that are qualitatively different from responses to milder extremes, we consider both biomass loss and recovery rates over time by reporting a time-integrated carbon loss as a result of UCE, relative to the absence of drought. Additionally, we explore how unprecedented droughts in combination with increasing atmospheric CO2 and/or temperature may affect ecosystem stability and carbon cycling. We explored these questions using simulations of pre-drought and post-drought conditions at well-studied forest sites using well-tested models (ED2 and LPJ-GUESS). The severity and patterns of biomass losses differed substantially between models. For example, biomass loss could be sensitive to either drought duration or drought intensity depending on the model approach. This is due to the models having different, but also plausible, representations of processes and interactions, highlighting the complicated variability of UCE impacts that still need to be narrowed down in models. Elevated atmospheric CO2 concentrations (eCO(2)) alone did not completely buffer the ecosystems from carbon losses during UCEs in the majority of our simulations. Our findings highlight the consequences of differences in process formulations and uncertainties in models, most notably related to availability in plant carbohydrate storage and the diversity of plant hydraulic schemes, in projecting potential ecosystem responses to UCEs. We provide a summary of the current state and role of many model processes that give way to different underlying hypotheses of plant responses to UCEs, reflecting knowledge gaps which in future studies could be tested with targeted field experiments and an iterative modeling-experimental conceptual framework.

In this paper, we present a chemical and kinematic analysis of two ultrafaint dwarf galaxies (UFDs), Aquarius II (Aqu II) and Bootes II (Boo II), using Magellan/IMACS spectroscopy. We present the largest sample of member stars for Boo II (12), and the largest sample of red giant branch members with metallicity measurements for Aqu II (eight). In both UFDs, over 80% of targets selected based on Gaia proper motions turned out to be spectroscopic members. In order to maximize the accuracy of stellar kinematic measurements, we remove the identified binary stars and RR Lyrae variables. For Aqu II, we measure a systemic velocity of -65.3 +/- 1.8 km s(-1) and a metallicity of [Fe/H] = -2.57(-0.17)(+0.17). When compared with previous measurements, these values display a similar to 6 km s(-1) difference in radial velocity and a decrease of 0.27 dex in metallicity. Similarly for Boo II, we measure a systemic velocity of -130.4(-1.1)(+1.4) km s(-1), more than 10 km s(-1) different from the literature, a metallicity almost 1 dex smaller at [Fe/H] =-2.71(-0.10)(+0.11), and a velocity dispersion 3 times smaller at sigma(nu hel) 2.9(-1.21)(+1.6)km s(-1). Additionally, we derive systemic proper-motion parameters and model the orbits of both UFDs. Finally, we highlight the extremely darkmatter-dominated nature of Aqu II and compute the J-factor for both galaxies to aid searches of dark matter annihilation. Despite the small size and close proximity of Boo II, it is an intermediate target for the indirect detection of dark matter annihilation due to its low-velocity dispersion and corresponding low dark matter density.