Sequence Analysis of Alginate-Derived Oligosaccharides by Negative-Ion Electrospray Tandem Mass Spectrometry

Negative-ion electrospray tandem mass spectrometry (ES-MS/MS) with collision-induced dissociation (CID) is attempted for sequence determination of alginate oligosaccharides, derived from polyanionic alginic acid, polymannuronate, and polyguluronate by partial depolymerization using either alginate lyase or mild acid hydrolysis. Sixteen homo- and hetero-oligomeric fragments were obtained after fractionation by gel-filtration and strong anion exchange high performance liquid chromatography. The product-ion spectra of these alginate oligosaccharides were dominated by intense B-, C-, Y-, and Z-type ions together with 0,2A- and 2,5A-ions of lower intensities. Internal mannuronate residues (M) produce weak but specific decarboxylated Zint-ions (Zint − 44 Da; int: denotes internal), which can be used for distinction of M and a guluronate residue (G) at an internal position. A reducing terminal M or G, although neither gives rise to a specific ion, can be identified by differences in the intensity ratio of fragment ions of the reducing terminal residue [2,5Ared]/[0,4Ared] (red: denotes reducing terminal)

Comparative Studies on the Characteristic Fatty Acid Profiles of Four Different Chinese Medicinal Sargassum Seaweeds by GC-MS and Chemometrics

Sargassum seaweeds produce abundant biomass in China and have long been used as herbal medicine and food. Their characteristic fatty acid (FA) profiles and related potential function in promoting cardiovascular health (CVH) have not been systematically investigated. In this study, FA profiles of four medicinal Sargassum were characterized using GC-MS. Principal component analysis was used to discriminate the four medicinal Sargassum, and orthogonal projection to latent structures discriminant analysis was carried out between the two official species HAI ZAO and between the two folk medicine species HAI QIAN. In all of the algae investigated, the major SFA and MUFA were palmitic and stearic acid, respectively, while the major PUFAs were linoleic, arachidonic, and eicosapentaenoic acid. S. fusiforme and S. horneri had higher concentrations of PUFAs. With respect to CVH, all of the studied species, particularly S. fusiforme, exhibited satisfactory levels such as PUFA/SFA ratio and n-6/n-3 ratio. Each species possesses a unique FA profile and is discriminated clearly. Potential key FA markers (between the two Chinese official species, and between the two folk species) are assessed. The study provides characteristic fatty acid profiles of four Chinese medicinal Sargassum and their related potential function in promoting CVH

Patterns of spread and adoption of millet agriculture along the Eastern Rim of the Tibetan Plateau: archaeobotanical evidence from Houzidong, Southwest China (4200-4000 Cal. BP)

The spread of domesticated crops has commonly occurred alongside broad patterns of long- and short-distance human movements and culture contact across regions. While exchange across Eurasia along the so-called Silk Road has been much discussed, recent work has revealed increasingly more evidence for early north-south contact along the eastern rim of the Tibetan Plateau. Main points of debate concern the timing and direction of the spread of agriculture and domesticated crops. This paper contributes to these discussions by presenting new data from macrobotanical remains and phytoliths from Houzidong in southwest Sichuan, a Neolithic site on the eastern rim of the Tibetan Plateau. The results show that the main crops during the late Neolithic (4200-4000 cal. BP) were foxtail millet (Setaria italica) and broomcorn millet (Panicum miliaceum), with a small amount of rice (Oryza sativa), but that agriculture was overall not a major focus. Rather, the subsistence at Houzidong like at other sites in the region was highly diverse, relying on gathering, hunting, and small-scale cultivation with considerable crop diversity aimed at minimizing the impact of potential crop failure. This paper shows that subsistence practices differed markedly between sites, local populations exploiting the rich natural resources in the respective ecological niches in various ways. We argue that the wide variety of food sources available in southwest China allowed people to mitigate risk but also made them more receptive to new food sources such as plant crops, experimenting with them and adding them to their portfolio. Similar patterns can be seen in the adoption and adaptation of other outside influences with each community picking and choosing what suited them best, thus creating the rich and varied patchwork of highly localized cultural phenomena that came to characterize southwest China