Targeted mutagenesis in rice using CRISPR-Cpf1 system

正Cpfl is a class 2/type V CRISPR effector that has been recently harnessed for genome editing(Zetsche et al.,2015;Hur et al.,2016;Kim et al.,2016).Cpfl recognizes thymidine-rich sequence as the protospacer-adjacent motif(PAM)at the 5'end of target sequences.In addition,Cpfl requires only a single shorter crRNA and     

Rapid breeding of pink-fruited tomato hybrids using the CRISPR/Cas9 system

<正>As one of the most important vegetables,tomato (Solanum lycopersicum) is extensively produced and consumed worldwide and substantially contributes to human nutrition and health (The Tomato Genome Consortium,2012).Although red tomatoes are the most common,pink tomatoes are more popular in Asia,particularly in China and Japan,because of their better taste (Ballester et al.,2010;Zhu et al.,2018).Compared with red tomatoes,pink tomatoes fail to accumulate the yellow-colored flavonoid pigment,naringenin chalcone (NarCh),in their peels,resulting in a colorless peel phenotype (Adato et al,2009;Ballester et al.,2010).Genetic     

Multiple abnormalities in the feet and associated changes elsewhere in the skeleton: The case of 3A-7 from a Capsian Site in Algeria

A skeleton with a number of abnormalities is described with full discussion of alternative diagnoses. In this complex case, the primary diagnosis is of avulsion of the stem of the bifurcate ligament causing a fracture of the anterior process of the calcaneus. The bilateral fracture identified in Skeleton 3A-7 from Site 12, a Capsian site in Algeria, is a result of the feet being inverted and plantar flexed: the fracture is prone to non-union, which is asymmetrical here. There is also a separate anomaly of the feet, 3rd cuneiform and 3rd metatarsal coalition, which was not the cause of trauma. The bifurcate ligament is a major stabilizer of the lateral Chopart (transverse talar) joint, and the trauma could lead to further issues: however, multiple other traumatic changes in 3A-7 most likely occurred at the same time, rather than as the result of pre-existing foot trauma. The asymmetry of the calcaneal condition and asymmetry of the sequelae of the original trauma led to long bone asymmetry, the result of locomotor difficulties.     

SAA-Cas9: A tunable genome editing system with increased bio-safety and reduced off-target effects

The site-specific nature and ease of handling of clustered regularly interspaced palindromic repeat(CRISPR)/Cas9 has fulfilled the decades-long goal of genome engineering,and thus has pushed the biological sciences into a new era in which site-directed manipulation of DNA is no longer a short slab(Doudna and Charpentier,2014).The incomparable power of this system also enabled unprecedented new opportunities for practical applications in agriculture,ecosystem and human health(Liu,2017).However,with the extremely rapid development and application of CRISPR system,concerns about its bio-safety have been increasing(Caplan et al.,2015;Taning et al.,2017).While multiple studies have addressed this issue,alternative options for regulating Cas9 are of great interest.As has been proved by increasing evidences,another well?known concern is the off-target effects,which could not only confound research experiments or breeding,but also cause unwanted side effects in the forthcoming therapeutic uses(Fu et aL,2013;Taning et al.,2017;Zhang et al.,2018).     

The effect of replacing the ester bond with an amide bond and of overall stereochemistry on the activity of daptomycin

Daptomycin, a cyclic lipodepsipeptide antibiotic, has been used clinically since 2003 to treat serious infections caused by Gram-positive bacteria. Although 37?years have passed since daptomycin’s discovery, its mechanism of action is still debated. In this report, the effect of replacing the ester bond with an amide bond, and overall stereochemistry, on daptomycin’s biological activity was examined. Two peptides were prepared in which the threonine4 residue in the active daptomycin analog, Dap-K6-E12-W13, was replaced with (2S,3R)-diaminobutyric acid ((2S,3R)-DABA) or its epimer (2S,3S-DABA) converting the ring-closing ester bond to an amide bond. Both of these peptides were found to be considerably less active than Dap-K6-E12-W13. These results, along with our previous studies on other daptomycin analogs, enabled us to conclude that the ester bond is crucial to daptomycin’s activity. ent-Dap-K6-E12-W13 was found to be at least 133-fold less active than Dap-K6-E12-W13, indicating that a chiral interaction with a chiral target is essential to daptomycin’s activity. Studies examining the binding of Dap-K6-E12-W13 and ent-Dap-K6-E12-W13 to model liposomes consisting of phosphatidylglycerol (PG) and phosphatidylcholine suggest that the stereochemistry of PG plays a crucial role in daptomycin-membrane interactions.     

Efficient generation of pink-fruited tomatoes using CRISPR/Cas9 system

正Tomato(Solanum lycopersicum)is the leading vegetable crop worldwide and an essential component of a healthy diet(Lin et al.,2014;Du et al.,2017).Fruit color is regarded as one of the most important commercial traits in tomato(The Tomato Genome Consortium,2012).Consumers in different regions have different color preferences.For example,European and American     

The synergy between RSC,Nap1 and adjacent nucleosome in nucleosome remodeling

Eukaryotes have evolved a specific strategy to package DNA. The nucleosome is a 147-base-pair DNA segment wrapped around histone core proteins that plays important roles regulating DNA-dependent biosynthesis and gene expression. Chromatin remodeling complexes (RSC, Remodel the Structure of Chromatin) hydrolyze ATP to perturb DNA-histone contacts, leading to nucleosome sliding and ejection. Here, we utilized tethered particle motion (TPM) experiments to investigate the mechanism of RSC-mediated nucleosome remodeling in detail. We observed ATP-dependent RSC-mediated DNA looping and nucleosome ejection along individual mononucleosomes and dinucleosomes. We found that nucleosome assembly protein 1 (Nap1) enhanced RSC-mediated nucleosome ejection in a two-step disassembly manner from dinucleosomes but not from mononucleosomes. Based on this work, we provide an entire reaction scheme for the RSC-mediated nucleosome remodeling process that includes DNA looping, nucleosome ejection, the influence of adjacent nucleosomes, and the coordinated action between Nap1 and RSC.     

The identification of novel acid isostere based inhibitors of the VPS10P family sorting receptor Sortilin

Using fragment based and structure based drug discovery strategies a series of novel Sortilin inhibitors has been identified. The inhibitors are based on the N-substituted 1,2,3-triazol-4-one/ol heterocyclic template. X-ray crystallography shows that the 1,2,3-triazol-4-one/ol acts as a carboxylic acid isostere, making a bi-dentate interaction with an arginine residue of Sortilin, an interaction which has not been previously characterised for this heterocycle.