Abstract Repair of DNA double-strand breaks (DSBs) with homologous chromosomes is a hallmark of meiosis that is mediated by recombination ‘bridges’ between homolog axes. This process requires cooperation of DMC1 and RAD51 to promote homology search and strand exchange. The mechanism(s) regulating DMC1/RAD51-ssDNA nucleoprotein filament and the components of ‘bridges’ remain to be investigated. Here we show that MEIOK21 is a newly identified component of meiotic recombination bridges and is required for efficient formation of DMC1/RAD51 foci. MEIOK21 dynamically localizes on chromosomes from on-axis foci to ‘hanging foci’, then to ‘bridges’, and finally to ‘fused foci’ between homolog axes. Its chromosome localization depends on DSBs. Knockout of Meiok21 decreases the numbers of HSF2BP and DMC1/RAD51 foci, disrupting DSB repair, synapsis and crossover recombination and finally causing male infertility. Therefore, MEIOK21 is a novel recombination factor and probably mediates DMC1/RAD51 recruitment to ssDNA or their stability on chromosomes through physical interaction with HSF2BP.

This study provides an efficient approach to study germ cell development using CAMSCs.

BackgroundThe psychological status of volunteers was investigated to provide a theoretical method for Phase I clinical trial management and result analysis.Material/MethodsThe Symptom Checklist 90 (SCL-90) and Eysenck Personality Questionnaire (EPQ) were used to assess the psychological status 200 healthy Chinese volunteers.ResultsSCL-90 results indicate that the average value of positive factors is 10.32±14.26 by self-assessment of healthy volunteers, somatization factor is 1.13±0.13, compulsive symptom factor is 1.29±0.27, interpersonal sensitivity factor is 1.31±0.21, depression factor is 1.26±0.33, anxiety factor is 1.21±0.21, hostility factor is 1.08±0.26, phobia factor is 1.05±0.18, paranoid factor is 1.12±0.23, and psychotic symptom factor is 1.17±0.26.ConclusionsCompared to the norm in China, the score of each factor of healthy volunteers was relatively low, with a statistically significant difference (P<0.001). EPQ results show that P score was 4.59±2.33, E score is 13.13±4.32, N score was 6.89±5.26, and L score was 13.21±4.25 for the 200 healthy volunteers. Compared to the norm in China, the P and N scores were lower, and the E and L scores were higher, with a statistically significant difference (P<0.001).

Based on the optical Raman lattice technique, we experimentally realize the Qi-Wu-Zhang model for quantum anomalous Hall phase in ultracold fermions with two-dimensional (2D) spin-orbit (SO) coupling. We develop a novel protocol of pump-probe quench measurement to probe, with minimal heating, the resonant spin flipping on particular quasi-momentum subspace called band-inversion surfaces. With this protocol we demonstrate a continuous crossover between 1D and 2D SO couplings by tuning the relative phase between two coherent Raman couplings, and detect the non-trivial topological band structures by varying the twophoton detuning. The non-trivial band topology is also observed by slowly loading the atoms into optical Raman lattices and measuring the spin textures. Our results show solid evidence for the realization of the minimal SO-coupled quantum anomalous Hall model, which can provide a feasible platform to investigate novel topological physics including the correlation effects with SO-coupled ultracold fermions.

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