LM rendezvous procedures - F mission, AS-505/CSM-106/LM-4 Final report

Rendezvous procedures for LM-4 and CSM for use in crew training and flight plannin

Draxin alters laminin organization during basement membrane remodeling to control cranial neural crest EMT

Premigratory neural crest cells arise within the dorsal neural tube and subsequently undergo an epithelial-to-mesenchymal transition (EMT) to leave the neuroepithelium and initiate migration. Draxin is a Wnt modulator that has been shown to control the timing of cranial neural crest EMT. Here we show that this process is accompanied by three stages of remodeling of the basement membrane protein laminin, from regression to expansion and channel formation. Loss of Draxin results in blocking laminin remodeling at the regression stage, whereas ectopic maintenance of Draxin blocks remodeling at the expansion stage. The latter effect is rescued by addition of Snail2, previously shown to be downstream of Draxin. Our results demonstrate an essential function for the Wnt modulator Draxin in regulating basement membrane remodeling during cranial neural crest EMT

Did you Pack your Keys? Smart Objects And Forgetfulness

Engineering and Physical Sciences Research Council (EPSRC) as part of the Centre for Doctoral Training in Media and Arts Technology at Queen Mary University of London

RNA-binding protein Elavl1/HuR is required for maintenance of cranial neural crest specification

Neural crest development is transcriptionally controlled via sequential activation of gene regulatory networks (GRNs). Recent evidence increasingly implicates a role for post-transcriptional regulation in modulating the output of these regulatory circuits. Using RNA-sequencing data from avian embryos to identify potential post-transcriptional regulators, we observed enrichment during early neural crest development of Elavl1, which encodes for the RNA-binding protein HuR. Immunohistochemical analyses revealed expression of HuR following establishment of the neural plate border. Perturbation of HuR resulted in premature neural crest delamination from the neural tube as well as significant reduction in transcripts associated with the neural crest specification GRN (Axud1 and FoxD3), phenotypes also observed with downregulation of the canonical Wnt inhibitor Draxin. RNA pulldown further shows that Draxin is a specific target of HuR. Importantly, overexpression of exogenous Draxin was able to rescue the cranial neural crest specification defects observed with HuR knockdown. Thus, HuR plays a critical a role in the maintenance of cranial neural crest specification, at least partially via Draxin mRNA stabilization. Together, these data highlight an important intersection of post-transcriptional regulation with modulation of the neural crest specification GRN

RNA-binding protein Elavl1/HuR is required for maintenance of cranial neural crest specification

Neural crest development is transcriptionally controlled via sequential activation of gene regulatory networks (GRNs). Recent evidence increasingly implicates a role for post-transcriptional regulation in modulating the output of these regulatory circuits. Using RNA-sequencing data from avian embryos to identify potential post-transcriptional regulators, we observed enrichment during early neural crest development of Elavl1, which encodes for the RNA-binding protein HuR. Immunohistochemical analyses revealed expression of HuR following establishment of the neural plate border. Perturbation of HuR resulted in premature neural crest delamination from the neural tube as well as significant reduction in transcripts associated with the neural crest specification GRN (Axud1 and FoxD3), phenotypes also observed with downregulation of the canonical Wnt inhibitor Draxin. RNA pulldown further shows that Draxin is a specific target of HuR. Importantly, overexpression of exogenous Draxin was able to rescue the cranial neural crest specification defects observed with HuR knockdown. Thus, HuR plays a critical a role in the maintenance of cranial neural crest specification, at least partially via Draxin mRNA stabilization. Together, these data highlight an important intersection of post-transcriptional regulation with modulation of the neural crest specification GRN

Apollo mission D performance analysis of rendezvous charts

Performance analysis of rendezvous charts for Apollo 9 missio

P-bodies are sites of rapid RNA decay during the neural crest epithelial-mesenchymal transition

The epithelial-mesenchymal transition (EMT) drives cellular movements during development to create specialized tissues and structures in metazoans, using mechanisms often coopted during metastasis. Neural crest cells are a multipotent stem cell population that undergo a developmentally regulated EMT and are prone to metastasis in the adult, providing an excellent model to study cell state changes and mechanisms underlying EMT. A hallmark of neural crest EMT during avian development is temporally restricted expression followed by rapid down-regulation of the Wnt antagonist Draxin. Using live RNA imaging, here we demonstrate that rapid clearance of Draxin transcripts is mediated post-transcriptionally via localization to processing bodies (P-bodies), small cytoplasmic granules which are established sites of RNA processing. Contrasting with recent work in immortalized cell lines suggesting that P-bodies are sites of storage rather than degradation, we show that targeted decay of Draxin occurs within P-bodies during neural crest migration. Furthermore, P-body disruption via DDX6 knockdown inhibits not only endogenous Draxin down-regulation but also neural crest EMT in vivo. Together, our data highlight a novel and important role for P-bodies in an intact organismal context−controlling a developmental EMT program via post-transcriptional target degradation

Photo-cathodes for the CERN CLIC Test Facility

Since 1993 the CLIC Test Facility (CTF) has used laser-illuminated Tellurium Alkali photo-cathodes as intense electron sources (up to 50 nC in 10 ps), for the Drive Beam of a two-beam accelerator. These cathodes have been produced and tested in our photo­emission laboratory and transported under vacuum to the CTF. They are placed in a 3 GHz RF gun with a 100 MV/m electric field. This RF gun produces a train of 48 pulses, each of 13.4 nC charge and 10 ps length. The CTF Probe Beam has used air­transportable cesium iodide + germanium photo­cathodes in another RF gun, which produces a single pulse of the same duration but with only 1 nC charge. The optical damage threshold in the laser is the main limitation of energy available on the photo­cathode. From an operational point of view, the photo­cathode lifetime is defined to be the time during which the cathode is able to produce the nominal charge with the nominal laser energy. After having recalled the main characteristics of the photo-cathodes tested, this note describes in more detail the performa nce obtained in operation. The possibility of photo-cathode production at the RF gun in a simplified evaporation chamber will also be discussed

Temporal changes in plasma membrane lipid content induce endocytosis to regulate developmental epithelial-to-mesenchymal transition

Epithelial-to-mesenchymal transition (EMT) is a dramatic change in cellular physiology during development and metastasis which involves coordination between cell signaling, adhesion, and membrane protrusions. These processes all involve dynamic changes in the plasma membrane, yet how membrane lipid content regulates membrane function during developmental EMT remains incompletely understood. By screening for differential expression of lipid-modifying genes over the course of EMT in avian neural crest, we have identified the ceramide-producing enzyme neutral sphingomyelinase 2 (nSMase2) as a critical regulator of a developmental EMT. nSMase2 expression begins at the onset of EMT, and in vivo knockdown experiments demonstrate that nSMase2 is necessary for neural crest migration. Further, we find that nSMase2 promotes Wnt and BMP signaling, and is required to activate the mesenchymal gene expression program. Mechanistically, we show that nSMase2 is sufficient to induce endocytosis, and that inhibition of endocytosis mimics nSMase2 knockdown. Our results support a model in which nSMase2 is expressed at the onset of neural crest EMT to produce ceramide and induce membrane curvature, thus increasing endocytosis of Wnt and BMP signaling complexes and activating pro-migratory gene expression. These results highlight the critical role of plasma membrane lipid metabolism in regulating transcriptional changes during developmental EMT programs