Chemical characterization and quantification of the brown algal storage compound laminarin

In search of a meaningful stress indicator for Fucus vesiculosus we found that the often used quantitative determination procedures for the polysaccharide laminarin (beta-1,3-glucan) result in different kind of problems, uncertainties and limitations. This chemical long-term storage form of carbon enables perennial brown algae in seasonally fluctuating ecosystems to uncouple growth from photosynthesis. Because of this high ecological relevance a reliable and precise method for determination and quantification of laminarin is needed. Therefore, a simple, cold water extraction method coupled to a new quantitative liquid chromatography-mass spectrometrical method (LC-MS) was developed. Laminarin was determined in nine out of twelve brown algal species, and its expected typical molar mass distribution of 2000-7000 Da was confirmed. Furthermore, laminarin consisted of a complex mixture of different chemical forms, since fifteen chemical laminarin species with distinct molecular weights were measured in nine species of brown algae. Laminarin concentrations in the algal tissues ranged from 0.03 to 0.86% dry weight (DW). The direct chemical characterization and quantification of laminarin by LC-MS represents a powerful method to verify the biochemical and ecological importance of laminarin for brown algae. Single individuals of Laminaria hyperborea, L. digitata, Saccharina latissima, F. serratus, F. vesiculosus, F. spiralis, Himanthalia elongata, Cystoseira tamariscifolia, Pelvetia canaliculata, Ascophyllum nodosum, Halidrys siliquosa and Dictyota dichotoma were collected in fall (18.11.2013) during spring low tide from the shore of Finavarra, Co. Clare, west coast of Ireland (53° 09' 25'' N, 09° 06' 58'' W). After sampling, the different algae were immediately transported to the lab, lyophilized and sent to the University of Rostock. Laminarin was extracted with cold ultrapure water from the algal samples. Before extraction they were ground to < 1 mm grain size with an analytical mill (Ika MF 10 Basic). The algal material (approx. 1.5 g DW) was extracted in ultrapure water (8 mL) on a shaker (250 rpm) for 5 h. After the addition of surplus ultrapure water (4 mL) and shaking manually, 1 mL of the sample was filter centrifuged (45 µm) at 14,000 rpm (Hettich Mikro 22 R). The slightly viscous supernatant was free of suspended material and converted into a microvial (300 µL) for further analysis. The extracts were analyzed using liquid chromatography-mass spectrometry (LC-MS) analysis (LTQ Velos Pro ion trap spectrometer with Accela HPLC, Thermo Scientific). Laminarin species were separated on a KinetexTM column (2.6 µm C18, 150 x 3 mm). The mobile phase was 90 % ultrapure water and 10 % acetonitrile, run isocratically at a flow rate of 0.2 mL min-1. MS was working in ESI negative ion mode in a mass range of 100 - 4000 amu. Glucose contents were determined after extraction using high-performance liquid chromatography (HPLC). Extracted samples were analyzed in an HPLC (SmartLine, Knauer GmbH) equipped with a SUPELCOGELTM Ca column (30 x 7,8 mm without preColumn) and RI-detector (S2300 PDA S2800). Water was used as eluent at a flow rate of 0.8 mL min-1 at 75 °C. Glucose was quantified by comparison of the retention time and peak area with standard solutions using ChromGate software. Mannitol was extracted from three subsamples of 10-20 mg powdered alga material (L. hyperborea, L. digitata, S. latissima, F. serratus, F. vesiculosus, F. spiralis, H. elongata, P. canaliculata, A. nodosum, H. siliquosa) and quantified, following the HPLC method described by Karsten et al. (1991). For analyzing carbon and nitrogen contents, dried algal material was ground to powder and three subsamples of 2 mg from each alga thalli were loaded and packed into tin cartridges (6×6×12 mm). The packages were combusted at 950 °C and the absolute contents of C and N were automatically quantified in an elemental analyzer (Elementar Vario EL III, Germany) using acetanilide as standard according to Verardo et al. (1990).

Sedimentology of ODP Leg 126 deep-water volcaniclastics

Three sites were drilled in the Izu-Bonin forearc basin during Ocean Drilling Program (ODP) Leg 126. High-quality formation microscanner (FMS) data from two of the sites provide images of part of a thick, volcaniclastic, middle to upper Oligocene, basin-plain turbidite succession. The FMS images were used to construct bed-by-bed sedimentary sections for the depth intervals 2232-2441 m below rig floor (mbrf) in Hole 792E, and 4023-4330 mbrf in Hole 793B. Beds vary in thickness from those that are near or below the resolution of the FMS tool (2.5 cm) to those that are 10-15 m thick. The bed thicknesses are distributed according to a power law with an exponent of about 1.0. There are no obvious upward thickening or thinning sequences in the bed-by-bed sections. Spaced packets of thick and very thick beds may be a response to (1) low stands of global sea level, particularly at 30 Ma, (2) periods of increased tectonic uplift, or (3) periods of more intense volcanism. Graded sandstones, most pebbly sandstones, and graded to graded-stratified conglomerates were deposited by turbidity currents. The very thick, mainly structureless beds of sandstone, pebbly sandstone, and pebble conglomerate are interpreted as sandy debris-flow deposits. Many of the sediment gravity flows may have been triggered by earthquakes. Long recurrence intervals of 0.3-1 m.y. for the very thickest beds are consistent with triggering by large-magnitude earthquakes (M = 9) with epicenters approximately 10-50 km away from large, unstable accumulations of volcaniclastic sand and ash on the flanks of arc volcanoes. Paleocurrents were obtained from the grain fabric of six thicker sandstone beds, and ripple migration directions in about 40 thinner beds; orientations were constrained by the FMS images. The data from ripples are very scattered and cannot be used to specify source positions. They do, however, indicate that the paleoenvironment was a basin plain where weaker currents were free to follow a broad range of flow paths. The data from sandstone fabric are more reliable and indicate that turbidity currents flowed toward 150? during the time period from 28.9 to 27.3 Ma. This direction is essentially along the axis of the forearc basin, from north to south, with a small component of flow away from the western margin of the basin.

Airborne hyperspectral image data of Heron Reef, Australia

This airborne hyperspectral (19 bands) image data of Heron Reef, Great Barrier Reef, Australia is derived from Compact Airborne Spectrographic Imager (CASI) data acquired on 1st and 3rd of July 2002, latitude -23.45, longitude 151.92. Processing and correction to at-surface data was completed by Karen Joyce (Joyce, 2004). Raw imagery consisted several images corresponding to the number of flight paths taken to cover the entire Heron Reef. Spatial resolution is one meter. Radiometric corrections converted the at-sensor digital number values to at surface spectral radiance values using sensor specific calibration coefficients and CSIRO's c-WomBat-c atmospheric correction software. Geometric corrections were done using field collected coordinates of features identified in the image. Projection used was Universal Transverse Mercator Zone 56 South and Datum used was WGS 84. Image data is in TIFF format.