ABSTRACT
italic>Dendrobium moniliforme is an important source of Dendrobii Caulis and one of the main sources of authentic Fengdou. The complete chloroplast genome of D. moniliforme was sequenced using Illumina Hiseq technology and its gene map and genomic structure were analyzed. Then comparative and phylogenetic analysis of the complete chloroplast genomes of D. moniliforme and its related species were conducted. The chloroplast genome of D. moniliforme was 150 754 bp in length and had a typical quadripartite structure with a large single copy (LSC, 84 818 bp), a small single copy (SSC, 14 124 bp) and two inverted repeats (IRs, 25 906 bp each). A total of 123 chloroplast genes were annotated, including 77 protein-coding genes, 38 tRNA genes and 8 rRNA genes, of which 17 genes contained introns. Bioinformatics analysis identified 53 SSR sites, most of which had A-T base preference. A phylogenetic tree was constructed using the chloroplast genome sequences of 33 Dendrobium species. The results showed that Dendrobium complex species were clustered in a single large branch, indicating that they were closely related. This study provides a scientific basis for the identification of D. moniliforme and the phylogenetic relationship of D. moniliforme complex species necessary for Herbgenomics research.
ABSTRACT
A highly sensitive electrochemical deoxyribonucleic acid(DNA) biosensor based on multi-walled carbon nanotubes(MWNT)/Ag-TiO_2 composite film was developed. The solution containing Ag-TiO_2-MWNT composite was casted on the carbon paste electrode surface to form a robust film, which combine the advantages of the good biocompatibility of Ag-TiO_2 naocomposite and the fine conductivity, as well as the large active surface area of carbon nanotubes. The composite could greatly improve the immobilization capacity of the probe DNA. The morphologies and electrochemistry of the nanocomposite film were investigated by scanning electron microscopy and electrochemical techniques including electrochemical impedance spectroscopy and cyclic voltammetry, respectively. DNA hybridization events were monitored by a label-free method of electrochemical impedance spectroscopy. This label-free electrochemical impedance DNA biosensor showed high sensitivity and selectivity for phosphinothricin acetyltransferase gene sequence assay. The multicomponents films also displayed a high stability during repeated regeneration and hybridization process.