No abstract

The connection between monosaccharides influences the structure, solubility, and biological function of carbohydrates. Although tandem mass spectrometry (MS/MS) often enables the compositional identification of carbohydrates, traditional MS/MS fragmentation methods fail to generate abundant cross-ring fragments of intrachain monosaccharides that could reveal carbohydrate connectivity. We examined the potential of helium-charge transfer dissociation (He-CTD) as a method of MS/MS to decipher the connectivity of β-1,4and β-1,3-linked oligosaccharides. In contrast to collision-induced dissociation (CID), He-CTD of isolated oligosaccharide precursors produced both glycosidic and cross-ring cleavages of each monosaccharide. The radical-driven dissociation in He-CTD induced single cleavage events, without consecutive fragmentations, which facilitated structural interpretation. He-CTD of various standards up to a degree of polymerization of 7 showed that β-1,4and β-1,3-linked carbohydrates can be distinguished based on diagnostic 3,5 A fragment ions that are characteristic for β-1,4-linkages. Overall, fragment ion spectra from He-CTD contained sufficient information to infer the connectivity specifically for each glycosidic bond. When testing He-CTD to resolve the order of β-1,4and β-1,3-linkages in mixed-linked oligosaccharide standards, He-CTD spectra sometimes provided less confident assignment of connectivity. Ion mobility spectrometry−mass spectrometry (IMS−MS) of the standards indicated that ambiguity in the He-CTD spectra was caused by isobaric impurities in the mixed-linked oligosaccharides. Radical-driven dissociation induced by He-CTD can thus expand MS/MS to carbohydrate linkage analysis, as demonstrated by the comprehensive fragment ion spectra on native oligosaccharides. The determination of connectivity in true unknowns would benefit from the separation of isobaric precursors, through UPLC or IMS, before linkage determination via He-CTD.

No abstract

Brown algae annually convert gigatons of carbon dioxide into carbohydrates, including the complex extracellular matrix polysaccharide fucoidan. Due to its persistence in the environment, fucoidan is potentially a pathway for marine carbon sequestration. Rates of fucoidan secretion by brown algae remain unknown due to the challenge of identifying and quantifying complex polysaccharides in seawater. We adapted the techniques of anion exchange chromatography, enzyme-linked immunosorbent assay, and biocatalytic enzyme-based assay for detection and quantification of fucoidan. We found the brown alga Fucus vesiculosus at the Baltic Sea coast of south-west Finland to secrete 0.3% of their biomass as fucoidan per day. Dissolved fucoidan concentrations in seawater adjacent to algae reached up to 0.48 mg L −1 . Fucoidan accumulated during incubations of F. vesiculosus , significantly more in light than in darkness. Maximum estimation by acid hydrolysis indicated fucoidan secretion at a rate of 28 to 40 mg C kg −1 h −1 , accounting for 44 to 50% of all exuded dissolved organic carbon. Composed only of carbon, oxygen, hydrogen, and sulfur, fucoidan secretion does not consume nutrients enabling carbon sequestration independent of algal growth. Extrapolated over a year, the algae sequester more carbon into secreted fucoidan than their biomass. The global utility of fucoidan secretion is an alternative pathway for carbon dioxide removal by brown algae without the need to harvest or bury algal biomass.

Sexual reproduction is fundamental to the maintenance and recovery of coraldominated communities in high-latitude and isolated locations, where replenishment often depends on local reproductive activity rather than recruitment from distant reefs. Rapa Nui (Easter Island) is one of the most remote islands in the Pacific, lying at the southern, subtropical edge of the range of reef-building scleractinians. Here, we describe the sexual reproduction and timing of the 2 dominant corals, Pocillopora verrucosa and Porites lobata. Reproductive activity was inferred from the identification and staging of gametes via histological analyses of monthly samples collected from December 2012 to May 2014 at 12 m depth at Motu Tautara (27°6.6' S, 109°25.5' W) with in situ temperature records. In P. verrucosa, the observed hermaphroditic activity spanned from December to January, resulting in mature oocytes of 117 µm mean diameter. In P. lobata, observed gonochoric activity spanned from December to March, resulting in mature oocytes of 180 µm mean diameter. The observed initiation of gametogenic cycles coincided with the onset of spring warming in both species. Inferred spawning of P. verrucosa followed a relatively calm period of daily variance reduction in local in situ temperature and wind speed prior to the peak in thermal conditions, whereas inferred spawning of P. lobata coincided with peak temperatures in one year but not the other. We suggest temporal restrictions of disruptive coastal activities such as dredging during coral spawning periods and mitigation of land-based sources of pollution and watershed discharge that may reduce water quality.

In the last centuries, new high-throughput technologies, including sequencing and mass-spectrometry, have emerged and are constantly refurbished in order to decipher the molecular code of life. In this review, we summarize the physiological background from genes via transcriptome to proteins and metabolites and discuss the variety of dimensions in which a biological entity may be studied. Herein, we emphasize regulatory processes which underlie the plasticity of molecular profiles on different ome layers. We discuss the four major fields of omic research, namely genomics, transcriptomics, proteomics, and metabolomics, by providing specific examples and case studies for (i) the assessment of functionality on molecular, organism, and community level; (ii) the possibility to use omic research for categorization and systematic efforts; and (iii) the evaluation of responses to environmental cues with a special focus on anthropogenic influences. Thereby, we exemplify the knowledge gains attributable to the integration of information from different omes and the enhanced precision in predicting the phenotype. Lastly, we highlight the advantages of combining multiple omics layers in assessing the complexity of natural systems as meta-communities and -organisms.