Yeast Rcl1 is a potential endonuclease that mediates pre-RNA cleavage at the A(2)-site to separate 18S rRNA from 5.8S and 25S rRNAs. However, the biological function of Rcl1 in opisthokonta is poorly defined. Moreover, there is no information regarding the exact positions of 18S pre-rRNA processing in zebrafish. Here, we report that zebrafish pre-rRNA harbours three major cleavage sites in the 5 ' ETS, namely -477nt (A '-site), -97nt (A(0)-site) and the 5 ' ETS and 18S rRNA link (A(1)-site), as well as two major cleavage regions within the ITS1, namely 208-218nt (site 2) and 20-33nt (site E). We also demonstrate that depletion of zebrafish Rcl1 mainly impairs cleavage at the A(1)-site. Phenotypically, rcl1(-/-) mutants exhibit a small liver and exocrine pancreas and die before 15 days post-fertilization. RNA-seq analysis revealed that the most significant event in rcl1(-/-) mutants is the up-regulated expression of a cohort of genes related to ribosome biogenesis and tRNA production. Our data demonstrate that Rcl1 is essential for 18S rRNA maturation at the A(1)-site and for digestive organogenesis in zebrafish. Rcl1 deficiency, similar to deficiencies in other ribosome biogenesis factors, might trigger a common mechanism to upregulate the expression of genes responsible for ribosome biogenesis.

We report a combined conventional Mossbauer and synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS) study of a series of basalt, andesite, dacite, and rhyolite glasses at temperatures ranging from 5 to 1223 K. These glasses were synthesized under controlled oxygen fugacities and span a wide range of Fe3+/Fe-tot ratios. As expected from theory, we find that in these glasses, the inverse of the Lamb-Mossbauer factor (the recoil-free fraction) correlates linearly with the fraction of the conventional Mossbauer spectrum that can be ascribed to Fe3+. Extrapolating the linear relationships to pure Fe3+ and Fe2+ endmembers yields a ratio for the Lamb-Mossbauer factors C of Fe3+ and Fe2+ of 1.203 & nbsp;+/- 0.017 (1r), with no clear dependence on the chemical composition of the glass. We show that the materials studied follow the harmonic approximation up to 1223 K for olivine and 773 K for basaltic glass, allowing us to extrapolate C in temperature. The temperature-dependence of C is well approximated by the formula C =& nbsp;(1.203 +/-& nbsp;0.033)(T=300) over the temperature range 50-750 K. This calibration is used to correct previous redox ratio determinations. We investigate how chemical composition and iron redox state influence the mean force constant of iron in glasses, a key driver of Fe isotopic fractionation during magma generation and differentiation. As previously documented by Dauphas et al. (2014), we find clear correlation between bond strength and iron redox ratio that is secondarily modulated by coordination effects in more alkali-rich felsic magmas. New data on sim-plified glass compositions reveal that network modifiers, notably K and Na, seem to exert an important control on Fe2+ bond strengths. The refined ratio of Mossbauer factors for Fe(2+ )and Fe3+ is used to improve on calibrations of iron redox state in geological glasses using XANES spectroscopy. We reevaluate the Fe3+/Fe-tot ratio of MORBs based on previously published XANES and Mossbauer data. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.

To further understand the long-debated origin of the high-pressure cubic-rhombohedral transition in FeO, we investigated the domain wall structure in Fe0.94O using high-pressure microdiffraction imaging techniques. The results reveal a non-reflection type domain wall structure forming due to the cubic-rhombohedral transition in Fe0.94O, which suggests the transformation could be associated with defects and is unlikely to be ferroelastic in nature. (C) 2012 American Institute of Physics. [doi:10.1063/1.3679117]

Brassinosteroids are essential phytohormones that have crucial roles in plant growth and development. Perception of brassinosteroids requires an active complex of BRASSINOSTEROID-INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE 1 (BAK1). Recognized by the extracellular leucine-rich repeat (LRR) domain of BRI1, brassinosteroids induce a phosphorylation-mediated cascade to regulate gene expression. Here we present the crystal structures of BRI1(LRR) in free and brassinolide-bound forms. BRI1(LRR) exists as a monomer in crystals and solution independent of brassinolide. It comprises a helical solenoid structure that accommodates a separate insertion domain at its concave surface. Sandwiched between them, brassinolide binds to a hydrophobicity-dominating surface groove on BRI1(LRR). Brassinolide recognition by BRI1(LRR) is through an induced-fit mechanism involving stabilization of two interdomain loops that creates a pronounced non-polar surface groove for the hormone binding. Together, our results define the molecular mechanisms by which BRI1 recognizes brassinosteroids and provide insight into brassinosteroid-induced BRI1 activation.

Background Corticotropin-releasing factor (CRF) mediates our body's overall responses to stress. The role of central CRF in stress-stimulated colonic motility is well characterized. We hypothesized that transient perturbation in expression of enteric CRF is sufficient to change stress-induced colonic motor and secretory responses. Methods Sprague-Dawley rats (adult, male) were subjected to 1-h partial restraint stress (PRS) and euthanized at 0, 4, 8, and 24h. CRF mRNA and peptide levels in the colon were quantified by real-time RT-PCR, enzyme immuno-assay and immunohistochemistry. Double-stranded RNA (dsRNA) designed to target CRF (dsCRF) was injected into the colonic wall to attain RNA interference-mediated inhibition of CRF mRNA expression. DsRNA for -globin was used as a control (dsControl). Four days after dsRNA injection, rats were subjected to 1-h PRS. Fecal output was measured. Ussing chamber techniques were used to assess colonic mucosal ion secretion and transepithelial tissue conductance. Key Results Exposure to PRS elevated CRF expression and increased CRF release in the rat colon. Injection of dsCRF inhibited basal CRF expression and prevented the PRS-induced increase in CRF expression, whereas CRF expression in dsControl-injected colons remained high after PRS. In rats treated with dsControl, PRS caused a significant increase in fecal pellet output, colonic baseline ion secretion, and transepithelial tissue conductance. Inhibition of CRF expression in the colon prevented PRS-induced increase in fecal output, baseline ion secretion, and transepithelial tissue conductance. Conclusions & Inferences These results provide direct evidence that transient perturbation in peripherally expressed CRF prevents colonic responses to stress.

Rapid advances in DNA synthesis techniques have made it possible to engineer viruses, biochemical pathways and assemble bacterial genomes. Here, we report the synthesis of a functional 272,871-base pair designer eukaryotic chromosome, synIII, which is based on the 316,617-base pair native Saccharomyces cerevisiae chromosome III. Changes to synIII include TAG/TAA stop-codon replacements, deletion of subtelomeric regions, introns, transfer RNAs, transposons, and silent mating loci as well as insertion of loxPsym sites to enable genome scrambling. SynIII is functional in S. cerevisiae. Scrambling of the chromosome in a heterozygous diploid reveals a large increase in a-mater derivatives resulting from loss of the MAT alpha allele on synIII. The complete design and synthesis of synIII establishes S. cerevisiae as the basis for designer eukaryotic genome biology.

High-pressure neutron powder diffraction, muon-spin rotation, and magnetization studies of the structural, magnetic, and the superconducting properties of the Ce-underdoped superconducting (SC) electron-doped cuprate system with the Nd2CuO4 (the so-called T') structure T'-Pr1.3-xLa0.7CexCuO4 with x = 0.1 are reported. Astrong reduction of the in-plane and out-of-plane lattice constants is observed under pressure. However, no indication of any pressure-induced phase transition from T' to the K2NiF4 (the so-called T) structure is observed up to the maximum applied pressure of p = 11 GPa. Large and nonlinear increase of the short-range magnetic order temperature T-so in T'-Pr1.3-xLa0.7CexCuO4 (x = 0.1) was observed under pressure. Simultaneous pressure causes a nonlinear decrease of the SC transition temperature T-c. All these experiments establish the short-range magnetic order as an intrinsic and competing phase in SC T'-Pr1.3-xLa0.7CexCuO4 (x = 0.1). The observed pressure effects may be interpreted in terms of the improved nesting conditions through the reduction of the in-plane and out-of-plane lattice constants upon hydrostatic pressure.

One challenge in studying high-temperature superconductivity (HTSC) stems from a lack of direct experimental evidence linking lattice inhomogeneity and superconductivity. Here, we apply synchrotron hard X-ray nanoimaging and small-angle scattering to reveal a novel micron-scaled ribbon phase in optimally doped Bi2Sr2CaCu2O8+delta (Bi-2212, with delta = 0.1). The morphology of the ribbon-like phase evolves simultaneously with the dome-shaped T-c behavior under pressure. X-ray absorption studies show that the increasing of T-c is associated with oxygen-hole redistribution in the CuO2 plan, while T-c starts to decrease with pressure when oxygen holes become immobile. Additional X-ray irradiation experiments reveal that nanoscaled short-range ordering of oxygen vacancies could further lower T-c which indicates that the optimal T-c is affected not only by an optimal morphology of the ribbon phase, but also an optimal distribution of oxygen vacancies. Our studies thereby provide for the first time compelling experimental evidence correlating the T-c with micron to nanoscale inhomogeneity.

The intertwined charge, spin, orbital, and lattice degrees of freedom could endow 5d compounds with exotic properties. Current interest is focused on electromagnetic interactions in these materials, whereas the important role of lattice geometry remains to be fully recognized. For this sake, we investigate pressure-induced phase transitions in the spin-orbit Mott insulator Sr3Ir2O7 with Raman, electrical resistance, and x-ray diffraction measurements. We reveal an interesting magnetic transition coinciding with a structural transition at 14.4 GPa, but without a concurrent insulator-metal transition. The conventional correlation between magnetic and Mott insulating states is thereby absent. The observed softening of the one-magnon mode can be explained by a reduced tetragonal distortion, while the actual magnetic transition is associated with tilting of the IrO6 octahedra. This work highlights the critical role of lattice frustration in determining the high-pressure phases of Sr3Ir2O7. The ability to control electromagnetic properties via manipulating the crystal structure with pressure promises a new way to explore new quantum states in spin-orbit Mott insulators.

Lineage-specific stem cells are critical for the production and maintenance of specific cell types and tissues in multicellular organisms. In Arabidopsis, the initiation and proliferation of stomatal lineage cells is controlled by the basic helix-loop-helix transcription factor SPEECHLESS (SPCH). SPCH-driven asymmetric and self-renewing divisions allow flexibility in stomatal production and overall organ growth. How SPCH directs stomatal lineage cell behaviors, however, is unclear. Here, we improved the chromatin immunoprecipitation (ChIP) assay and profiled the genome-wide targets of Arabidopsis SPCH in vivo. We found that SPCH controls key regulators of cell fate and asymmetric cell divisions and modulates responsiveness to peptide and phytohormone-mediated intercellular communication. Our results delineate the molecular pathways that regulate an essential adult stem cell lineage in plants.