ABSTRACT
To accurately discriminate Stellariae Radix from its adulterants, four leading candidate DNA barcoding markers were evaluated. Sixty samples including Stellariae Radix and its adulterants have been newly collected and their total genomic DNA was extracted. Four DNA barcoding markers ITS, rbcL, psbA-trnH and matK were amplified and sequenced. Their sequence characteristic analyses, Kimura-2-parameter (K2P) distance calculation and Neighbor-joining (NJ) phylogenetic tree constructions were accomplished using the MEGA 7.0 software. DNA Barcoding gaps of the four DNA barcoding markers were estimated by the distributions of inter- and intra-sequence specific variations. Species identification efficiency was calculated using the BLAST method. The results showed that ITS had the highest (95.2%) while matK demonstrated the lowest (75%) PCR and sequencing efficiency. The length range of the four markers were in the ranger of 211-797 bp, and the G+C content of ITS was highest (54.35%). The identification efficiency of matK and ITS was 92% and 90% respectively. Barcoding gap could be found in ITS sequences. The NJ phylogenetic tree constructed using ITS sequences showed that samples of Stellariae Radix were separately formed into one clade, and samples of adulterants like Stellaria bistyla were clearly belong to different branches from Stellariae Radix, whereas NJ trees constructed using psbA-trnH, rbcL and matK could not differentiate Stellariae Radix from its adulterants. Therefore, ITS regions as DNA barcodes can stably and accurately distinguished Stellariae Radix from its adulterants, and provide a new technique for modern identification of Stellariae Radix.
ABSTRACT
Nerve growth factor(NGF) was firstly discovered as a member of neurotrophin family,and the research and development of NGF has been lasting more than fifty years since its discovery.To this end,a two-step and high –yield chromatographic method which consists of cation ion-exchange chromatography and reversed-phase chromatography was reported to isolate recombinant human beta nerve growth factor(? –NGF) secreted by constructed Chinese hamster ovary cells(CHO/dhfr-) from the culture media.Through the process of purification,the purity of protein which was determined by SDS-PAGE and RP-HPLC has reached to 95%,and the recovery of ? –NGF routed by RP-HPLC could be 70%.Furthermore,the biological activity of final purified protein evaluated by PC12 cells and dorsal root ganglia(DRG) exhibited the same performance as the standard protein of ? –NGF bought from Sigma,which indicated that there is no loss of biological activity through the isolation process.The conclusion suggested that an economical isolation method of recombinant human ? –NGF could be practiced on the industrial process of purification.