Goosecoid acts cell autonomously in mesenchyme-derived tissues during craniofacial development

Mice homozygous for a targeted deletion of the homeobox gene Goosecoid (Gsc) have multiple craniofacial defects. To understand the mechanisms responsible for these defects, the behavior of Gsc-null cells was examined in morula aggregation chimeras. In these chimeras, Gsc-null cells were marked with beta-galactosidase (beta-gal) activity using the ROSA26 lacZ allele. In addition, mice with a lacZ gene that had been introduced into the Gsc locus were used as a guide to visualize the location of Gsc-expressing cells. In Gsc-null\u3c-\u3ewild-type chimeras, tissues that would normally not express Gsc were composed of both Gsc-null and wild-type cells that were well mixed, reflecting the overall genotypic composition of the chimeras. However, craniofacial tissues that would normally express Gsc were essentially devoid of Gsc-null cells. Furthermore, the nasal capsules and mandibles of the chimeras had defects similar to Gsc-null mice that varied in severity depending upon the proportion of Gsc-null cells. These results combined with the analysis of Gsc-null mice suggest that Gsc functions cell autonomously in mesenchyme-derived tissues of the head. A developmental analysis of the tympanic ring bone, a bone that is always absent in Gsc-null mice because of defects at the cell condensation stage, showed that Gsc-null cells had the capacity to form the tympanic ring condensation in the presence of wild-type cells. However, analysis of the tympanic ring bones of 18.5 d.p.c. chimeras suggests that Gsc-null cells were not maintained. The participation of Gsc-null cells in the tympanic ring condensation of chimeras may be an epigenetic phenomenon that results in a local environment in which more precursor cells are present. Thus, the skeletal defects observed in Gsc-null mice may reflect a regional reduction of precursor cells during embryonic development

Prospects for Tin-Containing Halide Perovskite Photovoltaics

Tin-containing metal halide perovskites have enormous potential as photovoltaics, both in narrow band gap mixed tin–lead materials for all-perovskite tandems and for lead-free perovskites. The introduction of Sn(II), however, has significant effects on the solution chemistry, crystallization, defect states, and other material properties in halide perovskites. In this perspective, we summarize the main hurdles for tin-containing perovskites and highlight successful attempts made by the community to overcome them. We discuss important research directions for the development of these materials and propose some approaches to achieve a unified understanding of Sn incorporation. We particularly focus on the discussion of charge carrier dynamics and nonradiative losses at the interfaces between perovskite and charge extraction layers in p-i-n cells. We hope these insights will aid the community to accelerate the development of high-performance, stable single-junction tin-containing perovskite solar cells and all-perovskite tandems

The morphogenetic role of midline mesendoderm and ectoderm in the development of the forebrain and the midbrain of the mouse embryo

The anterior midline tissue (AML) of the late gastrula mouse embryo comprises the axial mesendoderm and the ventral neuroectoderm of the prospective forebrain, midbrain and rostral hindbrain. In this study, we have investigated the morphogenetic role of defined segments of the AML by testing their inductive and patterning activity and by assessing the impact of their ablation on the patterning of the neural tube at the early-somite-stage. Both rostral and caudal segments of the AML were found to induce neural gene activity in the host tissue; however, the de novo gene activity did not show any regional characteristic that might be correlated with the segmental origin of the AML. Removal of the rostral AML that contains the prechordal plate resulted in a truncation of the head accompanied by the loss of several forebrain markers. However, the remaining tissues reconstituted Gsc and Shh activity and expressed the ventral forebrain marker Nkx2.1. Furthermore, analysis of Gsc-deficient embryos reveals that the morphogenetic function of the rostral AML requires Gsc activity. Removal of the caudal AML led to a complete loss of midline molecular markers anterior to the 4th somite. In addition, Nkx2.1 expression was not detected in the ventral neural tube. The maintenance and function of the rostral AML therefore require inductive signals emanating from the caudal AML. Our results point to a role for AML in the refinement of the anteroposterior patterning and morphogenesis of the brain

Elucidating Mechanisms behind Ambient Storage-Induced Efficiency Improvements in Perovskite Solar Cells

ペロブスカイト太陽電池の常温熟成機構の解明. 京都大学プレスリリース. 2021-02-17.Initial improvement in power conversion efficiency (PCE) during ambient storage is often seen in perovskite solar cells (PSCs). In this work, we studied the origin of PCE enhancement by ambient storage on typical n-i-p PSCs. We found improvements in both fill factor and open-circuit voltage during the first 2 days of storage. By analyzing temperature and light intensity-dependent VOC, we found that the charge recombination mechanism changed from surface- to bulk-dominated because of defect passivation at the perovskite surface upon storage. In addition, we found that storage improves the conductivity and lowers the highest occupied molecular orbital level of the spiro-OMeTAD, improving charge extraction. These results show that there is more than one factor causing the storage-induced improvements in perovskite solar cells

A study of a C Α, Β -didehydroalanine homo-oligopeptide series in the solid-state by 13 C cross-polarization magic angle spinning NMR

The fully extended peptide conformation (2.0 5 -helix) has been investigated for the first time in the solid-state by 13 C cross-polarization magic angle spinning NMR. The compounds examined are members of a terminally protected, homo-oligopeptide series (from monomer through hexamer) based on C Α, Β -didehydroalanine. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35198/1/551_ftp.pd

Molecular basis of sugar recognition by collectin-K1 and the effects of mutations associated with 3MC syndrome

Background Collectin-K1 (CL-K1, or CL-11) is a multifunctional Ca2+-dependent lectin with roles in innate immunity, apoptosis and embryogenesis. It binds to carbohydrates on pathogens to activate the lectin pathway of complement and together with its associated serine protease MASP-3 serves as a guidance cue for neural crest development. High serum levels are associated with disseminated intravascular coagulation, where spontaneous clotting can lead to multiple organ failure. Autosomal mutations in the CL-K1 or MASP-3 genes cause a developmental disorder called 3MC (Carnevale, Mingarelli, Malpuech and Michels) syndrome, characterised by facial, genital, renal and limb abnormalities. One of these mutations (Gly204Ser in the CL-K1 gene) is associated with undetectable levels of protein in the serum of affected individuals. Results In this study, we show that CL-K1 primarily targets a subset of high-mannose oligosaccharides present on both self- and non-self structures, and provide the structural basis for its ligand specificity. We also demonstrate that three disease-associated mutations prevent secretion of CL-K1 from mammalian cells, accounting for the protein deficiency observed in patients. Interestingly, none of the mutations prevent folding nor oligomerization of recombinant fragments containing the mutations in vitro. Instead, they prevent Ca2+ binding by the carbohydrate-recognition domains of CL-K1. We propose that failure to bind Ca2+ during biosynthesis leads to structural defects that prevent secretion of CL-K1, thus providing a molecular explanation of the genetic disorder. Conclusions We have established the sugar specificity of CL-K1 and demonstrated that it targets high-mannose oligosaccharides on self- and non-self structures via an extended binding site which recognises the terminal two mannose residues of the carbohydrate ligand. We have also shown that mutations associated with a rare developmental disorder called 3MC syndrome prevent the secretion of CL-K1, probably as a result of structural defects caused by disruption of Ca2+ binding during biosynthesis

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Challenges and strategies toward long term stability of lead free tin based perovskite solar cells

Due to their outstanding optoelectronic properties, lead based halide perovskite materials have been applied as efficient photoactive materials in solution processed solar cells. Current record efficiencies offer the promise to surpass those of silicon solar cells. However, uncertainty about the potential toxicity of lead based halide perovskite materials and their facile dissolution in water requires a search for new alternative perovskite like materials. Thanks to the foresight of scientists and their experience in lead based halide perovskite preparation, remarkable results have been obtained in a short period of time using lead free perovskite compositions. However, the lower solar to energy conversion efficiency and long term stability issues are serious drawbacks that hinder the potential progression of these materials. Here, we review and analyse strategies in the literature and the most promising solutions to identify the factors that limit the power conversion efficiency and long term stability of lead free tin based perovskite solar cells. In the light of the current state of the art, we offer perspectives for further developing these promising material