Enhancer trapping in zebrafish using the Sleeping Beauty transposon

Background: Among functional elements of a metazoan gene, enhancers are particularly difficult to find and annotate. Pioneering experiments in Drosophila have demonstrated the value of enhancer "trapping" using an invertebrate to address this functional genomics problem. Results: We modulated a Sleeping Beauty transposon-based transgenesis cassette to establish an enhancer trapping technique for use in a vertebrate model system, zebrafish Danio rerio. We established 9 lines of zebrafish with distinct tissue- or organ-specific GFP expression patterns from 90 founders that produced GFP-expressing progeny. We have molecularly characterized these lines and show that in each line, a specific GFP expression pattern is due to a single transposition event. Many of the insertions are into introns of zebrafish genes predicted in the current genome assembly. We have identified both previously characterized as well as novel expression patterns from this screen. For example, the ET7 line harbors a transposon insertion near the mkp3 locus and expresses GFP in the midbrain-hindbrain boundary, forebrain and the ventricle, matching a subset of the known FGF8-dependent mkp3 expression domain. The ET2 line, in contrast, expresses GFP specifically in caudal primary motoneurons due to an insertion into the poly(ADPribose) glycohydrolase (PARG) locus. This surprising expression pattern was confirmed using in situ hybridization techniques for the endogenous PARG mRNA, indicating the enhancer trap has replicated this unexpected and highly localized PARG expression with good fidelity. Finally, we show that it is possible to excise a Sleeping Beauty transposon from a genomic location in the zebrafish germline. Conclusions: This genomics tool offers the opportunity for large-scale biological approaches combining both expression and genomic-level sequence analysis using as a template an entire vertebrate genome. © 2004 Balciunas et al; licensee BioMed Central Ltd

3D printing hybrid organometallic polymer-based biomaterials via laser two-photon polymerization

Materials with microscale structures are gaining increasing interest due to their range of technical and medical applications. Additive manufacturing approaches to such objects via laser two-photon polymerization, also known as multiphoton fabrication, enable the creation of new materials with diverse and tunable properties. Here, we investigate the properties of 3D structures composed of organometallic polymers incorporating aluminium, titanium, vanadium and zirconium. The organometallic polymer-based materials were analysed using a variety of techniques including SEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy analysis and contact angle measurements and their biocompatibility was tested in vitro. Cell viability and mode of death were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and acridine orange/ethidium bromide staining. Polymers incorporating Al, Ti and Zr supported cell adhesion and proliferation, and showed low toxicity in vitro, whereas the organometallic polymer incorporating V was shown to be cytotoxic. Inductively coupled plasma optical emission spectrometry suggested that leaching of the V from the organometallic polymer is the likely cause of this. The preparation of the organometallic polymers is straightforward and both simple 2D and complex 3D structures can be fabricated with ease. Resolution tests of the newly developed organometallic polymer incorporating Al show that suspended lines with widths down to 200 nm can be fabricated. We believe that the materials described in this work show promising properties for the development of objects with sub-micron features for biomedical applications (e.g. biosensors, drug delivery devices, tissue scaffolds etc.). © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

Supplement 1: Hollow-core-waveguide compression of multi-millijoule CEP-stable 3.2 μm pulses

Supplementary material Originally published in Optica on 20 December 2016 (optica-3-12-1308

Ultrafast magnetic scattering on ferrimagnets enabled by a bright Yb-based soft x-ray source

International audienceDevelopment of ultrafast table-top x-ray sources that can map various spin, orbital, and electronic configurations and reordering processes on their natural time and length scales is an essential topic for modern condensed matter physics as well as ultrafast science. In this work, we demonstrate spatiotemporally resolved resonant magnetic scattering (XRMS) to probe the inner-shell 4d electrons of a rare-earth (RE) composite ferrimagnetic system using a bright > 200 e V soft x-ray high harmonic generation (HHG) source, which is relevant for future energy-efficient, high-speed spintronic applications. The XRMS is enabled by direct driving of the HHG process with power-scalable, high-energy Yb laser technology. The optimally phase-matched broadband plateau of the HHG offers a record photon flux ( > 2 × 1 0 9 p h o t o n s / s / 1 % bandwidth) with excellent spatial coherence and covers the entire resonant energy range of RE’s N 4 , 5 edges. We verify the underlying physics of our x-ray generation strategy through the analysis of microscopic and macroscopic processes. Using a CoTb alloy as a prototypical ferrimagnetic system, we retrieve the spin dynamics, and resolve a fast demagnetization time of 500 ± 126 f s , concomitant with an expansion of the domain periodicity, corresponding to a domain wall velocity of ∼ 750 m / s . The results confirm that, far from cross-contamination of low-energy absorption edges in multi-element systems, the highly localized states of 4 d electrons associated with the N 4 , 5 edges can provide high-quality core-level magnetic information on par with what can be obtained at the M edges, which is currently accessible only at large-scale x-ray facilities. The analysis also indicates the rich material-, composition-, and probing-energy-dependent driving mechanism of RE-associated multicomponent systems. Considering the rapid emergence of high-power Yb lasers combined with novel nonlinear compression technology, this work indicates potential for next-generation high-performance soft x-ray HHG-based sources in future extremely photon-hungry applications on the table-top scale, such as probing electronic motion in biologically relevant molecules in their physiological environment (liquid phase), and advanced coherent imaging of nano-engineered devices with 5 ∼ 8 n m resolution

Collectivist ideals and Soviet consumer spaces: mikrorayon commercial centres in Vilnius, Lithuania and Tallinn, Estonia

This chapter focuses on Soviet mikrorayon centres—multifunctional social, and commercial centres—built in large housing estates in Vilnius, Lithuania and Tallinn, Estonia from the 1960s to the 1980s. In both countries, ensuring proper services to modern citizens was initially based on the conceptual model of a multistage domestic service system with small shops integrated into the urban fabric next to homes, and larger mikrorayon centres with self-service supermarkets reachable by foot without crossing wide roads. Mikrorayon centres also represented a novel type of urban space. New pedestrian commercial centres, influenced by the Vällingby centre in Stockholm and Tapiola centre near Helsinki, operated as a simulation of traditional city centres in sparse, freely planned new settlements. We argue that the theoretical model of multistage domestic services, as well the ideological and communal mission of the centres, was quickly reworked into a type of space that embraced consumption and individual behaviour within the framework of collectivism. The study shows how the architectural form and visual aesthetic of the centres had a specific role in this. As such, the Soviet mikrorayon centres were the product and defining part of the hybrid nature of late Soviet society and represent a peculiar type of spatiality where conflicting value systems do not exclude each other but instead interact