Target-selected mutagenesis of the rat

The rat is one of the most extensively studied model organisms, and with its genome being sequenced, tools to manipulate gene function in vivo have become increasingly important. We here report proof of principle for target-selected mutagenesis as a reverse genetic or knockout approach for the rat

Characterising the two-phase flow and mixing performance in a gas-mixed anaerobic digester: Importance for scaled-up applications

This study aimed to characterise the gas-liquid flow and mixing behaviour in a gas-mixed anaerobic digester by improving phase interaction modelling using Computational Fluid Dynamics (CFD). A 2D axisymmetric model validated with experimental data was set up using an Eulerian-Eulerian method. Uncertainty factors, including bubble size, phase interaction forces and liquid rheology were found to significantly influence the flow field. A more reliable and complete validation was obtained by critical comparison and assessment of the referred experimental data, compared to the models reported in other studies. Additionally, justifiable corrections and predictions in detail were obtained. Mixing was evaluated by trajectory tracking of a large number of particles based on an Euler-Lagrange method. The mixing performance approximated to a laminar-flow reactor (LFR) that distinctly deviated from expected continuous stirred tank reactor (CSTR) design, indicating limited enhancement from the applied gas-sparging strategy in the studied digester. The study shows the importance of a proper phase-interaction description for a reliable hydrodynamic characterisation and mixing evaluation in gas-mixed digesters. Validations, bend to experimental data without a critical assessment, may lead to an inaccurate model for further scaled-up applications.Sanitary EngineeringImPhys/Imaging PhysicsExecutive boardEnvironmental Fluid Mechanic

Generation of gene knockouts and mutant models in the laboratory rat by ENU-driven target-selected mutagenesis.

OBJECTIVE: The rat is one of the most important model organisms for biomedical and pharmacological research. However, the generation of novel models for studying specific aspects of human diseases largely depends on selection for specific traits using existing rat strains, thereby solely depending on naturally occurring variation. This study aims to provide the tools to manipulate the rat genome in a more directed way. METHODS: We developed robust, automated, and scaleable reverse genetic methodology based on ENU (N-ethyl-N-nitrosourea)-driven target-selected mutagenesis. Optimal mutagenesis conditions have been determined in three different rat strains and a universal, rapid, and cost-effective dideoxy resequencing-based screening setup was established for mutation discovery. The effectiveness of the approach is illustrated by the identification of 120 induced mutations in a set of genes of interest, including six that result in unique rat knockout models due to the introduction of premature stop codons. In addition, 56 mutations were found that change amino acids, including critical residues in transmembrane domains of receptors and channels. CONCLUSIONS: The approach described here allows for the systematic generation of knockout and protein function altering alleles in the rat. The resulting induced rat models will be powerful tools for studying many aspects of a wide variety of human diseases

Generation of gene knockouts and mutant models in the laboratory rat by ENU-driven target-selected mutagenesis.

Contains fulltext : 49935.pdf (publisher's version ) (Closed access)OBJECTIVE: The rat is one of the most important model organisms for biomedical and pharmacological research. However, the generation of novel models for studying specific aspects of human diseases largely depends on selection for specific traits using existing rat strains, thereby solely depending on naturally occurring variation. This study aims to provide the tools to manipulate the rat genome in a more directed way. METHODS: We developed robust, automated, and scaleable reverse genetic methodology based on ENU (N-ethyl-N-nitrosourea)-driven target-selected mutagenesis. Optimal mutagenesis conditions have been determined in three different rat strains and a universal, rapid, and cost-effective dideoxy resequencing-based screening setup was established for mutation discovery. The effectiveness of the approach is illustrated by the identification of 120 induced mutations in a set of genes of interest, including six that result in unique rat knockout models due to the introduction of premature stop codons. In addition, 56 mutations were found that change amino acids, including critical residues in transmembrane domains of receptors and channels. CONCLUSIONS: The approach described here allows for the systematic generation of knockout and protein function altering alleles in the rat. The resulting induced rat models will be powerful tools for studying many aspects of a wide variety of human diseases

Characteristics of energy production and dissipation around a bubble rising in water

© 2018 A numerical simulation on the rise behaviour of a bubble rising in stagnant water at Re ˜ 800–1300 has been conducted. It is found that vorticity generated at the side of the bubble is transferred to the wake region, forming chains of hairpin vortices that are regularly shed and transported downstream. The resulting fluctuations in shape, trajectory, and rise velocity were found to conform well to experimental observations. The fluctuations in velocity resulting from the unsteady wakes were analysed through a fixed-frame approach about the centre of mass of the bubble. The average turbulent kinetic energy in the near wake region was found to be ˜1.4–4.8% with respect to the average kinetic energy of the bubble. The production of the turbulent kinetic energy was found to occur predominantly at the near wake region of the bubble, mostly as a result of normal and tangential gradients of the mean streamwise velocity. Interestingly, several regions of negative rate of energy production were identified, namely at the top and side interfaces of the bubble. Overall, the ratio of positive-to-negative production rate was found to be ˜2.4–3.1, resulting in a net conversion towards smaller-scale fluctuations from the mean flow. Small–scale dissipation was found to occur throughout the wake of the bubble