Non-homologous end joining in class switch recombination: the beginning of the end

Immunoglobulin class switch recombination (CSR) is initiated by a B-cell-specific factor, activation-induced deaminase, probably through deamination of deoxycytidine residues within the switch (S) regions. The initial lesions in the S regions are subsequently processed, resulting in the production of DNA double-strand breaks (DSBs). These breaks will then be recognized, edited and repaired, finally leading to the recombination of the two S regions. Two major repair pathways have been implicated in CSR, the predominant non-homologous end joining (NHEJ) and the alternative end-joining (A-EJ) pathways. The former requires not only components of the ‘classical’ NHEJ machinery, i.e. Ku70/Ku80, DNA-dependent protein kinase catalytic subunit, DNA ligase IV and XRCC4, but also a number of DNA-damage sensors or adaptors, such as ataxia–telangiectasia mutated, γH2AX, 53BP1, MDC1, the Mre11–Rad50–NBS1 complex and the ataxia telangiectasia and Rad3-related protein (ATR). The latter pathway is not well characterized yet and probably requires microhomologies. In this review, we will focus on the current knowledge of the predominant NHEJ pathway in CSR and will also give a perspective on the A-EJ pathway

Trajectory Optimization of High-Speed Robotic Positioning with Suppressed Motion Jerk via Improved Chicken Swarm Algorithm

For the trajectory optimization of the time–jerk of robotic arms with a chicken swarm optimization algorithm, using five-order B-spline interpolation can ensure smooth and continuous acceleration, but, due to the performance problems of the algorithm, the low solution accuracy and the slow convergence speed, the ideal trajectory curve cannot be obtained. To address these problems, an improved chicken swarm algorithm based on a parallel strategy and dynamic constraints (PDCSO) is proposed, where the rooster update method is employed with a parallel strategy using X-best guidance and a Levy flight step. Dynamic constraints for the rooster are given, followed by the hens, and the optimal rooster position that improved the convergence accuracy while preventing the local optimum was determined. Simulation experiments using 18 classical test functions showed that the PDCSO algorithm outperformed other comparative algorithms in terms of convergence speed, solution accuracy and solution stability. Simulation validation in ADAMS and real machine tests proved that PDCSO can effectively reduce the running time and motion shock for robotic arms and improve the execution efficiency of such arms

Directing electrochemical reaction mechanism via interfacial control for better sulfur cathode

The "shuttle effect" in ether electrolyte or nucleophilic reaction in carbonate electrolyte are major obstacles to developing of lithium-sulfur (Li-S) batteries. Superficial sulfur on the outside of microporous carbon host can occur"shuttle effect" in ether electrolyte or nucleophilic reaction in carbonate electrolyte, which may affect the electrochemical reaction mechanism for lithium-sulfur batteries and need to be further clarified. Herein, we rationally designed microporous carbon and non-microporous carbon as the sulfur hosts, and manipulated the distribution of sulfur via interfacial control in cathode material, exhibiting diverse electrochemical behavior in carbonate electrolyte and ether electrolyte. The surface composition of the electrode was confirmed by ex-situ XPS and verified by in-situ XRD, which contributes to demonstrating the definite reaction mechanisms of lithium-sulfur batteries in the different electrolytes. The results show only the sulfur confined in microporous structure is active via "solid-solid" pathway, and the presence of sulfur on the outer surface of the cathode electrode has the negative effect on electrochemical performance in both electrolytes, which should be avoided in the fabrication of carbon/sulfur composites. Based on microporous carbon/sulfur composites, the lithiated GeS full cell was proposed and exhibited superior cycling performance and high Coulombic Efficiency