Air-stable azomethine ylides with an unusual pattern of charge distribution were efficiently prepared via the rhodium-catalyzed reaction between pyridines and 1-sulfonyl-1,2,3-triazoles. This reaction allowed for the first example of the catalytic multicomponent [5 + 2] cycloaddition reactions, thus resulting in the formation of biologically active 1,4-diazepine compounds.

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A metal-catalyst-free, mild, and efficient synthetic protocol for polycyclic 1,4-benzodiazepines via cascade [5 + 2]/[2 + 2] cycloadditions between pyridinium zwitterions and arynes is reported. Mechanistic experiments revealed that pyridinium zwitterions act as 1,5-dipoles in [5 + 2] cycloadditions with arynes for the construction of 1,4-benzodiazepines, which further undergo [2 + 2] cycloaddition resulting in the one-pot formation of one C-N bond and three C-C bonds.

The rumen microbial ecosystem is a complex system where rumen fermentation processes involve interactions among microorganisms. There are important relationships between diet and the ruminal bacterial composition. Thus, we investigated the ruminal fermentation characteristics and compared ruminal bacterial communities using tag amplicon pyrosequencing analysis in Yanbian yellow steers, which were fed linseed oil (LO) and propionate precursors. We used eight ruminally cannulated Yanbian yellow steers (510 ± 5.8 kg) in a replicated 4 × 4 Latin square design with four dietary treatments. Steers were fed a basal diet that comprised 80% concentrate and 20% rice straw (DM basis, CON). The CON diet was supplemented with LO at 4%. The LO diet was also supplemented with 2% dl-malate or 2% fumarate as ruminal precursors of propionate. Dietary supplementation with LO and propionate precursors increased ruminal pH, total volatile fatty acid concentrations, and the molar proportion of propionate. The most abundant bacterial operational taxonomic units in the rumen were related to dietary treatments. Bacteroidetes dominated the ruminal bacterial community and the genus Prevotella was highly represented when steers were fed LO plus propionate precursors. However, with the CON and LO diet plus malate or fumarate, Firmicutes was the most abundant phylum and the genus Ruminococcus was predominant. In summary, supplementing the diets of ruminants with a moderate level of LO plus propionate precursors modified the ruminal fermentation pattern. The most positive responses to LO and propionate precursors supplementation were in the phyla Bacteriodetes and Firmicutes, and in the genus Ruminococcus and Prevotella. Thus, diets containing LO plus malate or fumarate have significant effects on the composition of the rumen microbial community.

Measuring genetic diversity in populations of a crop species is very important for understanding the genetic structure of and subsequently improving the crop species by genetic manipulation. Single-nucleotide amplified polymorphisms (SNAPs) among and within maize populations of waxy, dent, and sweet corns at 25 single-nucleotide polymorphism (SNP) sites in 6 kernel starch-synthesis genes (sh2, bt2, su1, ae1, wx1, and sh1) were determined. Because of the intensive selection of some favorable alleles in starch-synthesis genes during the breeding process, and the resultant strong linkage disequilibrium (LD), the number of haplotypes in each population was far less than expected. Subsequent phenetic clustering analysis with the SNAPs indicated that the dent, waxy, and sweet corns formed distinct subclusters, except in a few incidences. LD was surveyed among SNAPs of intragenic, intergenic, and intrachromosomal SNPs in whole and subpopulations, which revealed that some SNAPs showed high LD with many other SNAPs, but some SNAPs showed low or no significant LD with others, depending on the subpopulation, indicating that these starch genes have undergone different selection in each subpopulation during the breeding process. Because the starch synthesis genes used in this study are important in maize breeding, the genetic diversity, LD, and accessions having rare SNAP alleles might be valuable in maize improvement programs.