[Identification of plantaginis semen based on ITS2 and psbA-trnH sequences].

In order to evaluate the efficiency of ITS2 and psbA-trnH sequences used as DNA barcodes to distinguish Plantaginis Semen from its adulterants, we collected 71 samples of Plantaginis Semen and its adulterants. The ITS2 and psbA-trnH sequences were aligned through Clustal W, and the genetic distances were calculated by kimura 2-parameter (K2P) model and the Neighbor-Joining (NJ) phylogenetic trees were constructed using MEGA 5.1. The results indicated that the ITS2 sequence lengths of Plantago asiatica and P. depressa were 199 bp and 200 bp, respectively; the maximum intra-specific K2P distance were lower than the minimum inter-specific K2P distance; the NJ tree based on ITS2 sequence indicated that Plantaginis Semen and its adulterants could be distinguished clearly. The sequence lengths of psbA-trnH of both P. asiatica and P. depressa were 340 bp; the maximum intra-specific K2P distances were lower than the minimum inter-specific K2P distance; the NJ tree based on psbA-trnH sequence showed that Plantaginis Semen can be distinguished clearly from its adulterants except for P. major. Therefore, ITS2 sequences can be used as an ideal DNA barcode to distinguish Plantaginis Semen from its adulterants.

The influence of isoleucine and arginine on biological activity and peptide-membrane interactions of antimicrobial peptides from the bactericidal domain of AvBD4.

In this study, the influence of isoleucine and arginine on the biological activity and peptide-membrane interactions of linear avian ß-defensin-4 (RL38) analogs was investigated. Results of biological activities showed that the antimicrobial activities of AvBD-4 analogs were closely related to hydrophobicity and amphipathicity. The peptide GLI19 with high hydrophobicity value and amphipathicity displayed broad spectrum antimicrobial activity against both gram-negative and gram-positive, whereas GLR19 with increasing multiple charges only exhibited activity against gram-negative. The interaction between peptides and the liposome membrane demonstrated that the peptides preferentially bound to negatively charged phospholipids over zwitterionic phospholipids, which supported the antimicrobial activity data. The outer membranes assay further demonstrated that GLI19 had a greater capacity than the other tested peptides to penetrate the cell membrane at a low concentration. Collectively, the peptides derived from the bactericidal domain of linear ß- defensins by truncation and hydrophobic amino acid substitution may be effective high-potential antibacterial agents.