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The water oxidation reaction (WOR) is a bottleneck in water splitting. Though many catalysts have been developed for this reaction, cost-effective, robust and efficient electrocatalysts based on non-precious metals are still highly desired. Herein reported are the synthesis, characterization and electrocatalytic properties of a dicopper(II) complex of the tetrapyridyl ligand N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,4-butanediamine (tpbn) and 2,2′-bipyridine (bpy), [Cu2(tpbn)(bpy)2](ClO4)4·2CH3COCH3 (1). The X-ray single crystallography analysis revealed that the tpbn ligand bridges two copper(II) centers located in a square pyramidal environment composed of one bpy ligand as well as two pyridyl and one amino groups of a tpbn. Complex 1 was a molecular electrocatalyst for WOR in 0.1 M NaOAc–NaOH solutions of pH 11.0–14.0. It was demonstrated that the incorporation of the ancillary ligand bpy into the tpbn-bridged dicopper(II) complex is crucial for the stabilization of the catalytic system and the enhancement of the activity. This work provided an alternative to achieve robust homogeneous catalytic systems with better performance.

Herein reported are the catalytic properties of the composites derived from complex [Cu 2 (tpbn)(CH 3 OH) 4 (ClO 4 ) 2 ](ClO 4 ) 2 ( 1 ) of tetrapyridyl ligand N,N,N′,N′-tetrakis(2-pyridyl-methyl)-1,4-butanediamine (tpbn). Complex 1 was a precursor of the composites catalytically active for water oxidation and CO 2 reduction reactions. Under the anodic potential of +1.20 V vs. Ag/AgCl, composites deposited on tin-doped indium oxide (ITO) electrodes from the solutions of complex 1 at pH 9.0–13.5 are highly active for water oxidation reaction (WOR). In contrast, under the cathodic potential of −1.20 V vs. Ag/AgCl, the species deposited on the copper surface from the solutions of complex 1 at pH 6.7 can efficiently catalyze CO 2 reduction to CO. Scanning electron microscopy (SEM) showed that the composites on ITO and Cu surfaces were particulate materials. X-ray photoelectron spectroscopy (XPS) and x-ray-excited Auger electron spectroscopy (XAES) analysis revealed that the composites mainly contain cuprous oxide (Cu 2 O) and copper oxide (CuO) in different ratios, which showed different catalytic activity to water oxidation and CO 2 reduction reactions in copper-free aqueous solutions under low overpotentials. This work demonstrated that metal complexes are good candidates for preparing robust, noble-metal-free catalysts for reactions relevant to renewable energy sources.

In animal cells, inhibition of non-homologous end joining (NHEJ) pathway improves the efficiency of homologous recombination (HR)-mediated double-strand brakes (DSBs) repair. To improve the efficiency of HR in sheep embryo fibroblasts, the NHEJ key molecule DNA ligase 4 (Lig4) was suppressed by siRNA interference. Four pairs of siRNA targeting Lig4 were designed and chemically synthesized. These siRNA were electro-transferred into sheep embryo fibroblasts respectively. Compared with the control groups, two pairs of siRNA were identified to effectively inhibit the expression of sheep Lig4 gene by qRT-PCR and Western blotting. The plasmid rejoining assay was adopted for examining the efficiency of HR-mediated DSB repair. I-SceⅠ endonuclease linearized vector and siRNA were co-transfected into sheep embryo fibroblasts. Flow cytometry analysis of cells after transfection for 72 h showed that suppression of Lig4 using siRNAs increased the rejoining efficiency of HR vector by 3-4 times compared with the control groups. Therefore, enhanced HR vector rejoining frequency by instant inhabition of Lig4 gene provides theoretical basis for improving gene targeting efficiency of sheep embryo fibroblasts.

Domestic sheep and their wild relatives harbor substantial genetic variants that can form the backbone of molecular breeding, but their genome landscapes remain understudied. Here, we present a comprehensive genome resource for wild ovine species, landraces and improved breeds of domestic sheep, comprising high-coverage (∼16.10×) whole genomes of 810 samples from 7 wild species and 158 diverse domestic populations. We detected, in total, ∼121.2 million single nucleotide polymorphisms, ∼61 million of which are novel. Some display significant (P < 0.001) differences in frequency between wild and domestic species, or are private to continent-wide or individual sheep populations. Retained or introgressed wild gene variants in domestic populations have contributed to local adaptation, such as the variation in the HBB associated with plateau adaptation. We identified novel and previously reported targets of selection on morphological and agronomic traits such as stature, horn, tail configuration, and wool fineness. We explored the genetic basis of wool fineness and unveiled a novel mutation (chr25: T7,068,586C) in the 3′-UTR of IRF2BP2 as plausible causal variant for fleece fiber diameter. We reconstructed prehistorical migrations from the Near Eastern domestication center to South-and-Southeast Asia and found two main waves of migrations across the Eurasian Steppe and the Iranian Plateau in the Early and Late Bronze Ages. Our findings refine our understanding of genome variation as shaped by continental migrations, introgression, adaptation, and selection of sheep., This study was financially supported by grants from the National Natural Science Foundation of China (Nos. 32061133010, 31825024, 31661143014, and 31972527), the National Key Research and Development Program-Key Projects of International Innovation Cooperation between Governments (2017YFE0117900), the External Cooperation Program of Chinese Academy of Sciences (152111KYSB20150010), and the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (No. 2019QZKK0501), and the Special Funds of the State Key Laboratory of Sheep Genetic Improvement and Healthy Production (Nos. 2018CA001, and 2019CA009, 2020CA001).