Inactivation of Pichia rhodanensis in relation to membrane and intracellular compounds due to microchip pulsed electric field (MPEF) treatment.

The effect of microchip pulsed electric field (MPEF) treatment on lethal and sublethal injury of Pichia rhodanensis (P. rhodanensis) were employed under 100-500 V for 20-100 pulses and the underlying mechanism of MPEF treatment was investigated as well. A 6.48 log10 reduction of P. rhodanensis was achieved at 500V for 80 pulse. The fluorescent staining with Propidium Iodide (PI) verified that the rate of sublethal injury cells maximum up to 27.2% under 200 V. MPEF can cause the damage of cell morphology and ultrastructure, meanwhile causing a decrease in cellular enzymes, antioxidant enzyme activity and cell membrane fluidity. The leakage of intracellular compounds (protein, nucleic acid, K+, Mg2+) and Ca2+-ATPase gradually increased as the growth of voltage, especially the proportion of protein in the supernatants increased from 2.0% to 26.4%. Flow cytometry analysis showed that MPEF has significant effect on membrane potential, but no obvious influence on non-specific esterase. MPEF can cause the changing of the secondary structure of protein, at the same time, double helix structure of DNA became loose and unwinding. These results provide a theoretical guidance for the widespread using of MPEF technology in the application of a non-thermal processing technique for food.

Integrated approach for identifying and evaluating the quality of Marsdenia tenacissima in the medicine market.

The accurate identification and quality evaluation of herbal medical plants is highly necessary to ensure their safety and efficacy. In present study, a new strategy combining DNA barcoding techniques with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) was proposed to facilitate the identification and quality control of M. tenacissima. In present work, the internal transcribed spacer 2 (ITS2) barcode was successfully used to identify 58 M. tenacissima samples and its adulterants. TLC successfully identified the other three M. tenacissima samples that failed to produce ITS2 regions. An adulterant was found in all the 62 samples. Moreover, the content of active medicinal ingredients is important for herbal plants quality. The content of tenacissoside H (TS-H) of M. tenacissima samples was determined by HPLC to range from 0.39% to 1.09%, which meets the criterion of the Chinese Pharmacopoeia. Thus, DNA barcoding coupled with TLC and HPLC is very promising to identify and evaluate the quality of M. tenacissima in the medicine market.

Barcode ITS2: a useful tool for identifying Trachelospermum jasminoides and a good monitor for medicine market.

Trachelospermum jasminoides is commonly used in traditional Chinese medicine. However, the use of the plant's local alternatives is frequent, causing potential clinical problems. The T. jasminoides sold in the medicine market is commonly dried and sliced, making traditional identification methods difficult. In this study, the ITS2 region was evaluated on 127 sequences representing T. jasminoides and its local alternatives according to PCR and sequencing rates, intra- and inter-specific divergences, secondary structure, and discrimination capacity. Results indicated the 100% success rates of PCR and sequencing and the obvious presence of a barcoding gap. Results of BLAST 1, nearest distance and neighbor-joining tree methods showed that barcode ITS2 could successfully identify all the texted samples. The secondary structures of the ITS2 region provided another dimensionality for species identification. Two-dimensional images were obtained for better and easier identification. Previous studies on DNA barcoding concentrated more on the same family, genus, or species. However, an ideal barcode should be variable enough to identify closely related species. Meanwhile, the barcodes should also be conservative in identifying distantly related species. This study highlights the application of barcode ITS2 in solving practical problems in the distantly related local alternatives of medical plants.