Organs that pump fluids by the coordinated beat of motile cilia through the lumen are integral to animal physiology. Such organs include the human airways, brain ventricles, and reproductive tracts. Although cilia organization and duct morphology vary drastically in the animal kingdom, ducts are typically classified as either carpet or flame designs. The reason behind this dichotomy and how duct design relates to fluid pumping remain unclear. Here, we demonstrate that two structural parameters -- lumen diameter and cilia-to-lumen ratio -- organize the observed duct diversity into a continuous spectrum that connects carpets to flames across all animal phyla. Using a unified fluid model, we show that carpet and flame designs maximize flow rate and pressure generation, respectively. We propose that convergence of ciliated organ designs follows functional constraints rather than phylogenetic distance, along with universal design rules for ciliary pumps.

Oxygen (O2), a dominant element in the atmosphere and an essential molecule for most life on Earth, is produced by the photosynthetic oxidation of water. However, metabolic activity can cause the generation of reactive O2 species (ROS) that can damage lipids, proteins, nucleic acids, and threaten cell viability. To identify and characterize mechanisms that allow cells to cope with the potentially negative effects of O2 reactivity, we performed a high-throughput O2 sensitivity screen on a genome-wide insertional mutant library of the unicellular alga Chlamydomonas reinhardtii. This screen led to the identification of several genes that, when disrupted, alter the cell’s sensitivity to O2 in the light. One of these genes encodes a protein designated Rubisco methyltransferase 2 (RMT2). Although this protein has homology to methyltransferases, it has not yet been demonstrated to catalyze methyltransferase reactions. Furthermore, the rmt2 mutant has not been observed to be compromised for the level of Rubisco (first enzyme of Calvin Benson Cycle; CBC), although the mutant cells were light sensitive, which is reflected by a marked decrease in the level of photosystem I (PSI), with much less of an impact on the other photosynthetic complexes; this mutant also shows upregulation of genes encoding the Ycf3 and Ycf4 proteins, which are associated with the biogenesis of PSI. The RMT2 protein has a chloroplast targeting sequence predicted by PredAlgo and PB-Chlamy1,2, and rescue of the mutant with a wild-type (WT) copy of the gene fused to the mNeonGreen fluorophore indicates that the protein is within the chloroplast and appears to be enriched in/around the pyrenoid (an intrachloroplast compartment, potentially hypoxic, that is found in many algae that contain the CO2-fixing enzyme Rubisco), but we also observe it more dispersed throughout the stroma. These results suggest that RMT2 may serve an important role in the biogenesis of PSI and that PSI biogenesis may be enriched around or within the pyrenoid, which may reflect the impact of O2/reactive O2 species on the efficiency with which PSI can assemble.

The GMT-Consortium Large Earth Finder (G-CLEF) is the first instrument for the Giant Magellan Telescope (GMT). G-CLEF is a fiber feed, optical band echelle spectrograph that is capable of extremely precise radial velocity measurement. G-CLEF Flexure Control Camera (FCC) is included as a part in G-CLEF Front End Assembly (GCFEA), which monitors the field images focused on a fiber mirror to control the flexure and the focus errors within GCFEA. FCC consists of an optical bench on which five optical components are installed. The order of the optical train is: a collimator, neutral density filters, a focus analyzer, a reimager and a detector (Andor iKon-L 936 CCD camera). The collimator consists of a triplet lens and receives the beam reflected by a fiber mirror. The neutral density filters make it possible a broad range star brightness as a target or a guide. The focus analyzer is used to measure a focus offset. The reimager focuses the beam from the collimator onto the CCD detector focal plane. The detector module includes a linear translator and a field de-rotator. We performed thermoelastic stress analysis for lenses and their mounts to confirm the physical safety of the lens materials. We also conducted the global structure analysis for various gravitational orientations to verify the image stability requirement during the operation of the telescope and the instrument. In this article, we present the opto-mechanical detailed design of G-CLEF FCC and describe the consequence of the numerical finite element analyses for the design.

The nucleosynthetic isotope composition of planetary materials provides a record of the heterogeneous distribution of stardust within the early solar system. In 2020 December, the Japan Aerospace Exploration Agency Hayabusa2 spacecraft returned to Earth the first samples of a primitive asteroid, namely, the Cb-type asteroid Ryugu. This provides a unique opportunity to explore the kinship between primitive asteroids and carbonaceous chondrites. We report high-precision mu 26Mg* and mu 25Mg values of Ryugu samples together with those of CI, CM, CV, and ungrouped carbonaceous chondrites. The stable Mg isotope composition of Ryugu aliquots defines mu 25Mg values ranging from -160 +/- 20 ppm to -272 +/- 30 ppm, which extends to lighter compositions relative to Ivuna-type (CI) and other carbonaceous chondrite groups. We interpret the mu 25Mg variability as reflecting heterogeneous sampling of a carbonate phase hosting isotopically light Mg (mu 25Mg similar to -1400 ppm) formed by low temperature equilibrium processes. After correcting for this effect, Ryugu samples return homogeneous mu 26Mg* values corresponding to a weighted mean of 7.1 +/- 0.8 ppm. Thus, Ryugu defines a mu 26Mg* excess relative to the CI and CR chondrite reservoirs corresponding to 3.8 +/- 1.1 and 11.9 +/- 0.8 ppm, respectively. These variations cannot be accounted for by in situ decay of 26Al given their respective 27Al/24Mg ratios. Instead, it requires that Ryugu and the CI and CR parent bodies formed from material with a different initial 26Al/27Al ratio or that they are sourced from material with distinct Mg isotope compositions. Thus, our new Mg isotope data challenge the notion that Ryugu and CI chondrites share a common nucleosynthetic heritage.

This paper is focused on the characterization of the thermal history of C-type asteroid Ryugu through the structure of the polyaromatic carbonaceous matter in the returned samples determined by Raman spectroscopy. Both intact particles and extracted Insoluble Organic Matter (IOM) from the two sampling sites on Ryugu have been characterized. The main conclusions are that (i) there is no structural difference of the polyaromatic component probed by Raman spectroscopy between the two sampling sites, (ii) in a manner similar to type 1 and 2 chondrites, the characterized Ryugu particles did not experience significant long-duration thermal metamorphism related to the radioactive decay of elements such as 26Al; (iii) some structural variability is nevertheless observed within our particle set. It can be interpreted as some particles having experienced some short duration and weak heating (R3 in the scale defined by Quirico et al. 2018 and TII or lower according to the scale defined by Nakamura, 2005).

Stem cells regenerate differentiated cells to maintain and repair tissues and organs. They also replenish themselves, i.e. self-renewal, for the regenerative process to last a lifetime. How stem cells renew is of critical biological and medical significance. Here we use the skeletal muscle stem cell (MuSC) to study this process. Using a combination of genetic, molecular, and biochemical approaches, we show that MPP7, AMOT, and TAZ/YAP form a complex that activates a common set of target genes. Among these targets, Carm1 can direct MuSC renewal. In the absence of MPP7, TAZ can support regenerative progenitors and activate Carm1 expression, but not to a level needed for self-renewal. Facilitated by the actin polymerization-responsive AMOT, TAZ recruits the L27 domain of MPP7 to up-regulate Carm1 to the level necessary to drive MuSC renewal. The promoter of Carm1, and those of other common downstream genes, also contain binding site(s) for YY1. We further demonstrate that the L27 domain of MPP7 enhances the interaction between TAZ and YY1 to activate Carm1. Our results define a renewal transcriptional program embedded within the progenitor program, by selectively up-regulating key gene(s) within the latter, through the combination of protein interactions and in a manner dependent on the promoter context.

Microbial phototrophic communities dominated early Earth and thrive to this day, particularly in extreme environments. We focus on the impact of diel oscillations on phototrophic biofilms, especially in hot springs, where oxygenic phototrophs are keystone species that use light energy to fix carbon and often nitrogen. They exhibit photo-motility and stratification, and alter the physicochemical environment by driving O2, CO2, and pH oscillations. Omics analyses reveal extensive genomic and functional diversity in biofilms, but linking this to a predictive understanding of their structure and dynamics remains challenging. This can be addressed by better spatiotemporal resolution of microbial interactions, improved tools for building and manipulating synthetic communities, and integration of empirical and theoretical approaches.

The Magellanic Stream (MS)-an enormous ribbon of gas spanning 140 degrees of the southern sky trailing the Magellanic Clouds-has been exquisitely mapped in the five decades since its discovery. However, despite concerted efforts, no stellar counterpart to the MS has been conclusively identified. This stellar stream would reveal the distance and 6D kinematics of the MS, constraining its formation and the past orbital history of the Clouds. We have been conducting a spectroscopic survey of the most distant and luminous red giant stars in the Galactic outskirts. From this data set, we have discovered a prominent population of 13 stars matching the extreme angular momentum of the Clouds, spanning up to 100(degrees) along the MS at distances of 60-120 kpc. Furthermore, these kinematically selected stars lie along an [alpha/Fe]-deficient track in chemical space from -2.5 < [Fe/H] <- 0.5, consistent with their formation in the Clouds themselves. We identify these stars as high-confidence members of the Magellanic Stellar Stream. Half of these stars are metal-rich and closely follow the gaseous MS, whereas the other half are more scattered and metal-poor. We argue that the metal-rich stream is the recently formed tidal counterpart to the MS, and we speculate that the metal-poor population was thrown out of the SMC outskirts during an earlier interaction between the Clouds. The Magellanic Stellar Stream provides a strong set of constraints-distances, 6D kinematics, and birth locations-that will guide future simulations toward unveiling the detailed history of the Clouds.