Multi-year assessment of paralytic shellfish toxins in hard clam species along the coastline of Jiangsu Province, China

Paralytic shellfish toxins(PSTs) are notorious neurotoxins that threaten public health and food safety worldwide.Although PST monitoring programs have recently been established throughout China, the profiles and variation of PSTs in important commercial clams(e.g., Mactra veneriformis, Ruditapes philippinarum, and Meretrix meretrix) along the Jiangsu Province coastline remain largely unexplored. In this study, a validated hydrophilic interaction liquid chromatography–tandem mass spectrometry(HILIC-MS/MS) method was used to examine PST profiles and levels in 540 clam samples from natural production areas along Jiangsu Province coastline during2014–2016. Although the PST levels(≤6.38 μg saxitotoxin equivalents(eq)/kg) were consistently below European Union regulatory limits(≤800 μg saxitotoxin eq/kg) during this time period, saxitotoxin, decarbamoylsaxitotoxin,and gonyautoxins 1 and 4 were detected, and nearly 40% of the samples were saxitotoxin-positive. The PST levels also varied significantly by seasons, with peak values observed in May during 2014–2016. This is the first systematic report of PSTs in clams from Jiangsu Province, and additional research and protective measures are needed to ensure the safety of clams harvested in this area.

Comparative chemical characters of Sparganii Rhizoma from different regions in China

Objective： To compare the chemical characters of Sparganii Rhizoma from different areas via chromatographic analysis and to establish a sensitive LC/MS method for quality assessment of Sparganii Rhizoma.Methods： Under the optimised HPLC-PDA chromatographic conditions,twenty batches of Sparganii Rhizoma were analyzed by HPLC fingerprints.Principal component analysis（PCA）,orthogonal projections to latent structures discriminant analysis（OPLS-DA）and hierarchical cluster analysis（HCA）were performed based on all peak areas of Sparganii Rhizoma fingerprints.Meanwhile,part of common peaks were subsequently quantified by UFLC-QTRAP-MS.Results： The similarity values of HPLC fingerprints fluctuated in a wide range of 0.511–0.973,which showed variable differences of chemical characters among Sparganii Rhizoma from twenty habitats.PCA,OPLS-DA and HCA indicated that samples could be divided into five groups with different chemical characters,which generally corresponded with their geographical distributions.A total of 31 peaks in HPLC fingerprints were marked,and eight of them were identified and quantified.The quantitative result was generally in agreement with the classifications based on HPLC fingerprints,which indicated that Sparganii Rhizoma samples from eastern China mostly contained more contents including phenolic acids and flavonoids.Conclusion： This study not only proved that there were relationships between geographic distributions and internal chemical compositions of plants,which could provide evidence to the traditional Chinese medicine concept ＂geo-authentic＂,but also supplied a sensitive and rapid simultaneous quantitive method for the quality estimation of Sparganii Rhizoma.

Effect of protein molecular weight on the mass transfer in protein mixing

与猛抛的混合蛋白质答案代理人在蛋白质结晶化实验是很重要的。在这个工作， interferometry 图象在与不同分子的重量混合二蛋白质期间被记录：14.6 kDa 的溶解酵素， 34.8 kDa 的 23.3 kDa 和胃朊酶的胰岛素被放在 Mach-Zehnder 干涉仪。蛋白质在接口的运输进程和动力学的比赛上的分子的重量依赖被学习。蛋白质答案的集中侧面被计算在混合过程期间分析集体转移。集体转移过程在与更高分子的重量混合蛋白质期间是更有效的，这被观察。另外，在接口上面的更快速的集中变化建议那传送对流可以统治散开。传送对流的现象在有更高分子的重量的蛋白质答案是更高的。