A database of microRNA expression patterns in Xenopus laevis

MicroRNAs (miRNAs) are short, non-coding RNAs around 22 nucleotides long. They inhibit gene expression either by translational repression or by causing the degradation of the mRNAs they bind to. Many are highly conserved amongst diverse organisms and have restricted spatio-temporal expression patterns during embryonic development where they are thought to be involved in generating accuracy of developmental timing and in supporting cell fate decisions and tissue identity. We determined the expression patterns of 180 miRNAs in Xenopus laevis embryos using LNA oligonucleotides. In addition we carried out small RNA-seq on different stages of early Xenopus development, identified 44 miRNAs belonging to 29 new families and characterized the expression of 5 of these. Our analyses identified miRNA expression in many organs of the developing embryo. In particular a large number were expressed in neural tissue and in the somites. Surprisingly none of the miRNAs we have looked at show expression in the heart. Our results have been made freely available as a resource in both XenMARK and Xenbase

On Hemangioblasts in Chicken

Hemangioblasts are bi-potential precursors for blood and endothelial cells (BCs and ECs). Existence of the hemangioblast in vivo by its strict definition, i.e. a clonal precursor giving rise to these two cell types after division, is still debated. Using a combination of mitotic figure analysis, cell labeling and long-term cell tracing, we show that, in chicken, cell division does not play a major role during the entire ventral mesoderm differentiation process after gastrulation. One eighth of cells do undergo at least one round of division, but mainly give rise to daughter cells contributing to the same lineage. Approximately 7% of the dividing cells that contribute to either the BC or EC lineage meet the criteria of true hemangioblasts, with one daughter cell becoming a BC and the other an EC. Our data suggest that hemangioblast-type generation of BC/EC occurs, but is not used as a major mechanism during early chicken development. It remains unclear, however, whether hemangioblast-like progenitor cells play a more prominent role in later development

Prostaglandin- and theophylline-induced Cl secretion in rat distal colon is inhibited by microtubule inhibitors

The aim of the present study was to examine the possible role of microtubules in chloride secretion by distal rat colon stimulated by prostaglandin (PGE 2 ) and theophylline. Distal colonic tissue from male rats was mounted in Ussing chambers, and short-circuit current (I sc ) was measured to assess chloride secretion. Three microtubule inhibitors, colchicine, nocodazole, and taxol, all inhibited the stimulated I sc and reduced the 60-min integrated secretory response to PGE 2 and theophylline (▪I sc dt) by 39–52%, whereas the inactive colchicine analog lumicolchicine did not. Atropine and tetrodotoxin had no effect on stimulated chloride secretion. To confirm the source of I sc , unidirectional 22 Na + and 36 Cl − fluxes were measured in tissues exposed to lumicolchicine (control) or colchicine. Control tissues absorbed both chloride [5.0 (1.1–8.6) (median and 95% confidence interval) μeq/cm 2 /hr] and sodium [2.8 (0.9–7.2) μeq/cm 2 /hr], and this net absorption was reduced by 96% and 79%, respectively, by treatment with PGE 2 and theophylline due to an increase in serosal-to-mucosal chloride and sodium movement. Colchicine-treated tissues exhibited similar net basal chloride and sodium absorption that was reduced by 71% and 75%, respectively, by treatment with PGE 2 and theophylline. Thus the PGE 2 - and theophylline-induced increase in chloride secretion was significantly reduced by colchicine ( P <0.05 by Wilcoxon rank-sum test), whereas colchicine had no effect on PGE 2 - and theophylline-induced changes in sodium fluxes. Furthermore, the colchinine-related changes in stimulated chloride secretion were numerically similar to colchicine-related changes in stimulated I sc . These findings indicate that microtubules are required for normal PGE 2 - and theophylline-induced chloride secretion in distal rat colon and suggest that induced chloride secretion may involve vesicular insertion of ion transporters into the plasma membrane or other microtubule-dependent regulatory processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44414/1/10620_2005_Article_BF01299864.pd

Support and Assessment for Fall Emergency Referrals (SAFER 1): Cluster Randomised Trial of Computerised Clinical Decision Support for Paramedics

Objective: To evaluate effectiveness, safety and cost-effectiveness of Computerised Clinical Decision Support (CCDS) for paramedics attending older people who fall. Design: Cluster trial randomised by paramedic; modelling. Setting: 13 ambulance stations in two UK emergency ambulance services. Participants: 42 of 409 eligible paramedics, who attended 779 older patients for a reported fall. Interventions: Intervention paramedics received CCDS on Tablet computers to guide patient care. Control paramedics provided care as usual. One service had already installed electronic data capture. Main Outcome Measures: Effectiveness: patients referred to falls service, patient reported quality of life and satisfaction, processes of care. Safety: Further emergency contacts or death within one month. Cost-Effectiveness Costs and quality of life. We used findings from published Community Falls Prevention Trial to model cost-effectiveness. Results: 17 intervention paramedics used CCDS for 54 (12.4%) of 436 participants. They referred 42 (9.6%) to falls services, compared with 17 (5.0%) of 343 participants seen by 19 control paramedics [Odds ratio (OR) 2.04, 95% CI 1.12 to 3.72]. No adverse events were related to the intervention. Non-significant differences between groups included: subsequent emergency contacts (34.6% versus 29.1%; OR 1.27, 95% CI 0.93 to 1.72); quality of life (mean SF12 differences: MCS −0.74, 95% CI −2.83 to +1.28; PCS −0.13, 95% CI −1.65 to +1.39) and non-conveyance (42.0% versus 36.7%; OR 1.13, 95% CI 0.84 to 1.52). However ambulance job cycle time was 8.9 minutes longer for intervention patients (95% CI 2.3 to 15.3). Average net cost of implementing CCDS was £208 per patient with existing electronic data capture, and £308 without. Modelling estimated cost per quality-adjusted life-year at £15,000 with existing electronic data capture; and £22,200 without. Conclusions: Intervention paramedics referred twice as many participants to falls services with no difference in safety. CCDS is potentially cost-effective, especially with existing electronic data capture

Integrin signalling regulates the expansion of neuroepithelial progenitors and neurogenesis via Wnt7a and Decorin

Development of the cerebral cortex requires regulation of proliferation and differentiation of neural stem cells and a diverse range of progenitors. Recent work suggests a role for extracellular matrix (ECM) and the major family of ECM receptors, the integrins. Here we show that enhancing integrin beta-1 signalling, by expressing a constitutively active integrin beta-1 (CA*β1) in the embryonic chick mesencephalon, enhances neurogenesis and increases the number of mitotic cells dividing away from the ventricular surface, analogous to sub-apical progenitors in mouse. Only non-integrin-expressing neighbouring cells (lacking CA*β1) contributed to the increased neurogenesis. Transcriptome analysis reveals upregulation of Wnt7a within the CA*β1 cells and upregulation of the ECM protein Decorin in the neighbouring non-expressing cells. Experiments using inhibitors in explant models and genetic knock-downs in vivo reveal an integrin-Wnt7a-Decorin pathway that promotes proliferation and differentiation of neuroepithelial cells, and identify Decorin as a novel neurogenic factor in the central nervous system

MicroRNA In Situ Hybridization on Whole-Mount Preimplantation Embryos

Whole-mount in situ hybridization (WISH) using antisense probes is widely used to visualize RNA sequences in embryos and to determine the precise site of expression in the different cells or tissues. The target sequence is hybridized with an antisense RNA probe, followed by visual or fluorescence detection to measure the site and level of expression. However, the detection of short RNA molecules is hampered by the reduced stringency of the probes for short transcripts. Here, we describe a procedure for WISH detection of short RNA molecules, like miRNAs, in mammalian preimplantation embryos using LNA-modified probes with high sensitivity and specificity