Xiaojun Yan

Analysis of Oligo-κ-carrageenan by Reversed Phase Ion-pair Ultra Performance Liquid Chromatography Coupled with Electrospray Ionization-Time of Flight-Mass Spectrometry

Abstract The reverse phase ion-pair ultra performance liquid chromatography coupled with electrospray ionization time of flight mass spectrometry (RPIP-UPLC-ESI-Q-TOF-MS) method was developed for the analyses and elucidation of sulfated oligosaccharides. Mass spectra were obtained by ESI-Q-TOF-MS in both positive and negative ionization modes. Oligo-κ-carrageenans were separated on BEH C 18 column using heptylamine (20 mM, pH 4) as the ion-pairing reagent and A (H 2 O with 25% heptylammonium formate) and B (MeOH with 25% heptylammonium formate) as gradient eluent. Thus, oligo-κ-carrageenans were separated until pentatetrasaccharides were obtained. In addition, abundant structural information was obtained through the MS spectrometric analysis, and all acid hydrolyzed oligo-κ-carrageenans were identified as odd-numbered oligosaccharides. To further confirm these compounds, polyacrylamide gel electrophoresis (PAGE) was carried out. Furthermore, the described method has wide applicability to rapidly screen and provide structural information of oligo-κ-carrageenans.

Analysis of Dimethylsulfide and Dimethylsulfoniopropionate in Marine Microalgae Culture

Abstract In this study, a sensitive analytical method was established for the determination of free dimethylsulfide (DMS), dissolved dimethylsulfoniopropionate (DMSPd) and particulate DMSP (DMSPp), in marine microalgal culture with solid phase microextraction-gas chromatography-mass spectrometry. The linearity was in the range of 0.01–10.0 μg l−1, the detection limit was 10.6 pg, the average recovery rate was 93.1% ± 1.3%, and the RSDs were lower than 5%. The DMS contents in the microalgal culture were determined separately for the upper phase with addition of NaCl, and the lower phase with addition of NaOH for 12 h, after centrifugation. The contents of DMS and DMSP in the microalgal culture were calculated from the difference value of DMS. The data of four microalgal species confirmed the results as previously reported in a literature. The microalgae belonged to Pyrrophyta and Prymnesiophyceae were the major DMS (P) producers, and the content of DMSPp in Pleurochrysis carterae was (13.8 ± 0.9) pg per cell.

Metabolite Changes of Cage-farming Pseudosciaena crocea during Recovery Process after Typhoon

Abstract Sera from yellow croaker ( Pseudosciaena crocea ), which were collected from the cage-farming area of Xiangshan Bay in China during recovery process after the super typhoon “Krosa,” were studied by Ultra Performance Liquid Chromatography-Quadrupole-Time of Flight Mass Spectrometry (UPLC/Q-TOF-MS) using electron spraying ionization with positive and negative modes, in an effort to find potential metabolic biomarkers and reveal their physiological changes. After the UPLC/Q-TOF-MS analysis, Principal Components Analysis (PCA) and Orthogonal Projection to Latent Structures Discriminant Analysis (O-PLS-DA) were achieved using SIMCA-P for marker selection and identification. According to the data, the main biomarkers were identified as phosphatidylcholine and lysophosphatidylcholine. The others were characterized as cortol and taurocholate. In the whole half a month period of the study, lysophosphatidylcholine, phosphatidylcholine with higher unsaturated acyl chains ( n > 9) and taurocholate showed time-dependent increasing trends, whereas phosphatidylcholine with lower unsaturated acyl chains ( n Pseudosciaena crocea during recovery process after typhoon

Benthic macrofaunal communities along an estuarine gradient in the Jiaojiang River estuary, China

Benthic macrofaunal communities along an estuarine gradient of a macrotidal estuary of the Jiaojiang River, China were analyzed to reveal spatial variations in those communities and their relationships with environmental variables. Benthic macrofauna were collected from 15 sampling stations in May and October 2010. Polychaetes and Mollusks are the dominant taxonomic groups. The species richness, density and Shannon diversity index generally tended to increase as one moved away from shore toward the outer stations of the estuary. Cluster analysis and multidimensional scaling ordinations indicated the presence of three distinct zones of macrofaunal communities in the estuary. Multivariate analyses showed a strong relationship exists between the macrofaunal communities and the environmental parameters in the Jiaojiang River estuary. Aside from salinity, dissolved inorganic nitrogen and soluble reactive phosphate contents were also the major factor affecting the structure of the macrofaunal communities. The results demonstrated the important effects of nutrient-load on the distributional patterns of benthic macrofaunal communities in nutrient-rich estuaries.