Structural and functional investigation of the human snRNP assembly factor AAR2 in complex with the RNase H like domain of PRPF8

Small nuclear ribonucleoprotein complexes snRNPs represent the main subunits of the spliceosome. While the assembly of the snRNP core particles has been well characterized, comparably little is known of the incorporation of snRNP specific proteins and the mechanisms of snRNP recycling. U5 snRNP assembly in yeast requires binding of the the Aar2 protein to Prp8p as a placeholder to preclude premature assembly of the SNRNP200 helicase, but the role of the human AAR2 homolog has not yet been investigated in detail. Here, a crystal structure of human AAR2 in complex with the RNase H like domain of the U5 specific PRPF8 PRP8F RH is reported, revealing a significantly different interaction between the two proteins compared with that in yeast. Based on the structure of the AAR2 PRPF8 RH complex, the importance of the interacting regions and residues was probed and AAR2 variants were designed that failed to stably bind PRPF8 in vitro. Protein interaction studies of AAR2 with U5 proteins using size exclusion chromatography reveal similarities and marked differences in the interaction patterns compared with yeast Aar2p and imply phosphorylation dependent regulation of AAR2 reminiscent of that in yeast. It is found that in vitro AAR2 seems to lock PRPF8 RH in a conformation that is only compatible with the first transesterification step of the splicing reaction and blocks a conformational switch to the step 2 like, Mg2 coordinated conformation that is likely during U5 snRNP biogenesis. These findings extend the picture of AAR2 PRP8 interaction from yeast to humans and indicate a function for AAR2 in the spliceosomal assembly process beyond its role as an SNRNP200 placeholder in yeas

Experimental investigation of the time and temperature dependent growth of fatigue cracks in Inconel 718 and mechanism based lifetime prediction

The following contribution deals with the growth of cracks in low-cycle fatigue (LCF) and thermomechanical fatigue (TMF) tested specimens of Inconel 718 measured by using the replica method. The specimens are loaded with different strain rates. The material shows a significantly higher crack growth rate if the strain rate is decreased. Electron backscatter diffraction (EBSD) is adopted to identify the failure mechanism and the misorientation relationship of failed grain boundaries in secondary cracks. The analyzed cracks propagated mainly transgranular but also intergranular failure can be observed in some areas. It is found that grain boundaries with coincidence site lattice (CSL) boundary structure are generally less susceptible for intergranular failure than grain boundaries with random misorientation. For modeling the experimentally identified crack behavior an existing model for fatigue crack growth based on the mechanism of time dependent elastic–plastic crack tip blunting is enhanced to describe environmental effects based on the mechanism of oxygen diffusion at the crack tip. For the diffusion process the temperature dependent parabolic diffusion law is assumed. As a result, the time dependent cyclic crack tip opening displacement (ΔCTOD) is used as representative value to describe both mechanisms. Thus, most of the included model parameters characterize the deformation behavior of the material and can be determined by independent material tests. With the determined material properties, the proposed model describes the experimentally measured crack growth curves very well. The model is validated based on predictions of the number of cycles to failure of LCF as well as in-phase and out-of-phase TMF tests in the temperature range between room temperature and View the MathML source and 650°C

LimiTT: link miRNAs to targets

Background: MicroRNAs (miRNAs) impact various biological processes within animals and plants. They complementarily bind target mRNAs, effecting a post-transcriptional negative regulation on mRNA level. The investigation of miRNA target interactions (MTIs) by high throughput screenings is challenging, as frequently used in silico target prediction tools are prone to emit false positives. This issue is aggravated for niche model organisms, where validated miRNAs and MTIs both have to be transferred from well described model organisms. Even though DBs exist that contain experimentally validated MTIs, they are limited in their search options and they utilize different miRNA and target identifiers. Results: The implemented pipeline LimiTT integrates four existing DBs containing experimentally validated MTIs. In contrast to other cumulative databases (DBs), LimiTT includes MTI data of 26 species. Additionally, the pipeline enables the identification and enrichment analysis of MTIs with and without species specificity based on dynamic quality criteria. Multiple tabular and graphical outputs are generated to permit the detailed assessment of results. Conclusion: Our freely available web-based pipeline LimiTT (https://bioinformatics.mpi-bn.mpg.de/) is optimized to determine MTIs with and without species specification. It links miRNAs and/or putative targets with high granularity. The integrated mapping to homologous target identifiers enables the identification of MTIs not only for standard models, but for niche model organisms as well

The effect of flash lamp annealing on the performance of MOTFTs

In this study, we report about investigations on the performance of non-IGZO thin-film transistors (MOTFTs) based on the metal-oxides IAZO and IZO. The metal-oxides for the channel and insulator were coated in a pilot-scale in-line coating machine ILA 900 by rf sputtering of a single magnetron system on 550×670 mm2 glass substrates (Gen 3.5 format) with a thickness of 0.5 mm. After coating, the films were annealed by in-line flash lamp annealing (FLA) in vacuum atmosphere. We investigated the effect of the FLA process step on the carrier mobility and the stability of the MOTFTs