Modular Synthesis of Polycarbonyl Compounds via Regioselective Hydration of Oxo-Alkynes.

A novel protocol has been developed for the modular synthesis of polycarbonyl compounds by catalytic hydration of 1,3-diketone-tethered alkynes. The hydration process exhibits good regioselectivity and high yields at room temperature, avoiding the use of strong acids and noble metals and the requirement for elevated temperatures. Mechanistic insights suggest that the hydration proceeds through a concerted process of alkyne protonation and remote carbonyl participation.

Diverse nucleotide substitutions in rice base editing mediated by novel TadA variants.

CRISPR-mediated base editors have been widely used to correct defective alleles and create novel alleles by artificial evolution for the rapid genetic improvement of crops. The editing capabilities of base editors strictly rely on the performance of various nucleotide modification enzymes. Compared with the well-developed adenine base editors (ABEs), cytosine base editors (CBEs) and dual base editors suffer from unstable editing efficiency and patterns at different genomic loci in rice, significantly limiting their application.

Plasma metabolites and risk of seven cancers: a two-sample Mendelian randomization study among European descendants.

Background: While circulating metabolites have been increasingly linked to cancer risk, the causality underlying these associations remains largely uninterrogated.

Methods: We conducted a comprehensive 2-sample Mendelian randomization (MR) study to evaluate the potential causal relationship between 913 plasma metabolites and the risk of seven cancers among European-ancestry individuals. Data on variant-metabolite associations were obtained from a genome-wide association study (GWAS) of plasma metabolites among 14,296 subjects.

miR2118 Negatively Regulates Bacterial Blight Resistance through Targeting Several Disease Resistance Genes in Rice.

Plant miRNAs are a class of noncoding RNA with a length of 21-24 nt that play an important role in plant responses to biotic and abiotic stresses. Bacterial blight (BB) caused by pv. () is one of the most serious bacterial diseases in rice.

CRISPR/Sc -mediated genome editing in rice.

Streptococcus canis Cas9 (ScCas9) is an RNA-guided endonuclease with NNG protospacer adjacent motif (PAM) specificity whose genome-editing activity in rice is locus-dependent. Here we investigated the performance of a ScCas9 variant named Sc at different NNG PAM sites in the rice genome; Sc harbors a T1227K mutation and the substitution of a positively charged loop (residues 367-376). Sc nuclease achieved broader genome editing compared to the original ScCas9, and its nickase improved targeted base editing in transgenic rice plants.

SpRY greatly expands the genome editing scope in rice with highly flexible PAM recognition.

Background: Plant genome engineering mediated by various CRISPR-based tools requires specific protospacer adjacent motifs (PAMs), such as the well-performed NGG, NG, and NNG, to initiate target recognition, which notably restricts the editable range of the plant genome.

Results: In this study, we thoroughly investigate the nuclease activity and the PAM preference of two structurally engineered SpCas9 variants, SpG and SpRY, in transgenic rice. Our study shows that SpG nuclease favors NGD PAMs, albeit less efficiently than the previously described SpCas9-NG, and that SpRY nuclease achieves efficient editing across a wide range of genomic loci, exhibiting a preference of NGD as well as NAN PAMs.

Base-Editing-Mediated Artificial Evolution of OsALS1 In Planta to Develop Novel Herbicide-Tolerant Rice Germplasms.

Recently developed CRISPR-mediated base editors, which enable the generation of numerous nucleotide changes in target genomic regions, have been widely adopted for gene correction and generation of crop germplasms containing important gain-of-function genetic variations. However, to engineer target genes with unknown functional SNPs remains challenging. To address this issue, we present here a base-editing-mediated gene evolution (BEMGE) method, employing both Cas9n-based cytosine and adenine base editors as well as a single-guide RNA (sgRNA) library tiling the full-length coding region, for developing novel rice germplasms with mutations in any endogenous gene.

Cas9-NG Greatly Expands the Targeting Scope of the Genome-Editing Toolkit by Recognizing NG and Other Atypical PAMs in Rice.

CRISPR technologies enabling precise genome manipulation are valuable for gene function studies and molecular crop breeding. However, the requirement of a protospacer adjacent motif (PAM), such as NGG and TTN, for Cas protein recognition restricts the selection of targetable genomic loci in practical applications of CRISPR technologies. Recently Cas9-NG, which recognizes a minimal NG PAM, was reported to expand the targeting space of genome editing in human cells, but it remains unclear whether this Cas9 variant can be used in plants.

[Specificity and inheritance of rBE3 and rBE4 endonuclease-induced gene modifications in rice].

To gain more insights into the rice base editor (rBE3 and rBE4), we evaluated the mutation efficiency, off-target and inheritance of OsSERK1(D428N) and pi-ta(S918F) genes modified with rBE endonucleases. We predicted and analyzed the putative off-target sites of the sgRNA designed for OsSERK1(D428N) and pi-ta(S918F) by PCR amplification and Sanger sequencing. Then we further characterized the inheritance and stability of targeted base mutations and T-DNA segregation in the progeny of the self-fertilized T0 plants.