Transcriptome analysis of leaves, roots and flowers of Panax notoginseng identifies genes involved in ginsenoside and alkaloid biosynthesis.

BACKGROUND: Panax notoginseng (Burk.) F.H. Chen is one of the most highly valued medicinal plants in the world. The major bioactive molecules are triterpene saponins, which are also known as ginsenosides. However, its large genome size has hindered the assembly of a draft genome by whole genome sequencing. Hence, genomic and transcriptomic details about P. notoginseng, especially its biosynthetic pathways and gene expression in different parts of the plant, have remained largely unknown until now. RESULTS: In this study, RNA sequencing of three different P. notoginseng tissues was performed using next generation DNA sequencing. After assembling the high quality sequencing reads into 107,340 unigenes, biochemical pathways were predicted and 9,908 unigenes were assigned to 135 KEGG pathways. Among them, 270 unigenes were identified to be involved in triterpene saponin biosynthesis. In addition, 350 and 342 unigenes were predicted to encode cytochrome P450s and glycosyltransferases, respectively, based on the annotation results, some of which encode enzymes responsible for the conversion of the triterpene saponin backbone into different ginsenosides. In particular, one unigene predominantly expressed in the root was annotated as CYP716A53v2, which probably participates in the formation of protopanaxatriol from protopanaxadiol in P. notoginseng. The differential expression of this gene was further confirmed by real-time PCR. CONCLUSIONS: We have established a global transcriptome dataset for P. notoginseng and provided additional genetic information for further genome-wide research and analyses. Candidate genes involved in ginsenoside biosynthesis, including putative cytochrome P450s and glycosyltransferases were obtained. The transcriptomes in different plant tissues also provide invaluable resources for future study of the differences in physiological processes and secondary metabolites in different parts of P. notoginseng.

Differential detection of megakaryocytic and erythroid DNA in plasma in hematological disorders.

The tissues of origin of plasma DNA can be revealed by methylation patterns. However, the relative DNA contributions from megakaryocytes and erythroblasts into plasma appeared inconsistent among studies. To shed light into this phenomenon, we developed droplet digital PCR (ddPCR) assays for the differential detection of contributions from these cell types in plasma based on megakaryocyte-specific and erythroblast-specific methylation markers. Megakaryocytic DNA and erythroid DNA contributed a median of 44.2% and 6.2% in healthy individuals, respectively. Patients with idiopathic thrombocytopenic purpura had a significantly higher proportion of megakaryocytic DNA in plasma compared to healthy controls (median: 59.9% versus 44.2%; P = 0.03). Similarly, patients with ß-thalassemia were shown to have higher proportions of plasma erythroid DNA compared to healthy controls (median: 50.9% versus 6.2%) (P < 0.0001). Hence, the concurrent analysis of megakaryocytic and erythroid lineage-specific markers could facilitate the dissection of their relative contributions and provide information on patients with hematological disorders.

Cuprous Oxide Based Chemiresistive Electronic Nose for Discrimination of Volatile Organic Compounds.

This paper reports a facile functionalization method on a metal-oxide semiconductor and a cuprous oxide (Cu2O) based chemiresistive electronic nose for the detection of volatile organic compounds (VOCs). A library of functionalized Cu2O nanospheres was developed through silanization using chemically diverse organosilanes. An electronic nose was fabricated with unmodified Cu2O nanospheres and five types of functionalized Cu2O nanospheres as the sensing elements. The electronic nose showed stable and rapid resistance responses to 25-200 ppm model VOCs, with the operating temperature of 180 °C. Single VOCs and ternary VOC mixtures could be discriminated by the electronic nose, and six types of tea leaves were also proved to be distinguishable as an illustration of the application of the electronic nose. We expected that the silanization could provide a simple approach for material diversification and the electronic nose would have further application in identification and discrimination of complex gas samples.