April 21, 2020  |  

Emergence of a ST2570 Klebsiella pneumoniae isolate carrying mcr-1 and blaCTX-M-14 recovered from a bloodstream infection in China.

The worldwide emergence of the plasmid-borne colistin resistance mediated by mcr-1 gene not only extended our knowledge on colistin resistance, but also poses a serious threat to clinical and public health [1, 2]. Since its first discovery, mcr-1-carrying Enterobacteriaceae from human, animal, food, and environmental origins have been widely identified, but few mcr-1-positive clinical strains of Klebsiella pneumoniae have been reported so far, especially when associated with community-acquired infections [3, 4]. Here, we report the emergence of a colistin-resistant K. pneumoniae isolate, which belonged to a rare sporadic clone, co-carrying mcr-1 and blaCTX-M-14 genes simultaneous recovered from a community-acquired bloodstream infection in China. Whole-genome sequencing and microbiological analysis were performed to elucidate its antimicrobial resistance mechanisms.


April 21, 2020  |  

Comprehensive identification of the full-length transcripts and alternative splicing related to the secondary metabolism pathways in the tea plant (Camellia sinensis).

Flavonoids, theanine and caffeine are the main secondary metabolites of the tea plant (Camellia sinensis), which account for the tea’s unique flavor quality and health benefits. The biosynthesis pathways of these metabolites have been extensively studied at the transcriptional level, but the regulatory mechanisms are still unclear. In this study, to explore the transcriptome diversity and complexity of tea plant, PacBio Iso-Seq and RNA-seq analysis were combined to obtain full-length transcripts and to profile the changes in gene expression during the leaf development. A total of 1,388,066 reads of insert (ROI) were generated with an average length of 1,762?bp, and more than 54% (755,716) of the ROIs were full-length non-chimeric (FLNC) reads. The Benchmarking Universal Single-Copy Orthologue (BUSCO) completeness was 92.7%. A total of 93,883 non-redundant transcripts were obtained, and 87,395 (93.1%) were new alternatively spliced isoforms. Meanwhile, 7,650 differential expression transcripts (DETs) were identified. A total of 28,980 alternative splicing (AS) events were predicted, including 1,297 differential AS (DAS) events. The transcript isoforms of the key genes involved in the flavonoid, theanine and caffeine biosynthesis pathways were characterized. Additionally, 5,777 fusion transcripts and 9,052 long non-coding RNAs (lncRNAs) were also predicted. Our results revealed that AS potentially plays a crucial role in the regulation of the secondary metabolism of the tea plant. These findings enhanced our understanding of the complexity of the secondary metabolic regulation of tea plants and provided a basis for the subsequent exploration of the regulatory mechanisms of flavonoid, theanine and caffeine biosynthesis in tea plants.


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