Tab. 1: Summary of available data about antifreeze peptides of polar fish

In the blood of Antarctic notothenioid and Arctic gadiform fishes, freezing is inhibited by antifreeze glycopeptide macromolecules (AFGP). These antifreeze molecules are built up of repeating tripeptide units (Ala-Ala-Thr)n, to which the disaccharide fl-D-galactosyl-(1->3)a-N-acetyl-D-galactosamine is linked through the hydroxyl oxygen of the threonyl residue. Species of Liparididae, Zoarcidae, Cottidae and Pleuronectidae synthezise only unglycosylated antifreeze peptides (AFP). It could be demonstrated for the Antarctic silverfish Pleuragramma antarcticum that the synthesis of AFGP is not constitutive but rather regulated by water temperature. Moreover a novel glycopeptid was isolated and characterised from P. antarcticum, the Pleuragramma-antifreeze glycopeptid (PAGP). The level of antifreeze concentration was dependent on the ambient water temperature, the depth of distribution, the life cycle and the evolution of the species. Surprisingly, detectable AFGPs in perciform fish of the Antarctic and gadiform fish of the Arctic and Antarctic could illustrate, that before the continental drift occurred a precursor glycopeptid existed, and that the existence of freezing resistance in some species reflects the past glaciation. The wide distribution and high heterogeneity of AFPs point to the assumption that these peptides are results of cold shock stress responses.

n-Alkanes and lignin in bottom sediments of the Norwegian Sea

Investigations of bottom sediments from the central and northern parts of the Norwegian Sea including study regions at the Storegga landslide, the Haakon Mosby mud volcano, and Knipovich Ridge were carried out. Concentration of n-alkanes in bottom sediments from these regions ranges from 0.53 to 22.1 µg/g of dry sediments that corresponds to 0.02-1.97% of Corg. Molecular composition of hydrocarbons indicates mixed allochtonous-authochtonous genesis of total organic matter (TOC) formed by hydrobiota and residuals of terrestrial plants. Terrigenous organic mater dominates in bottom sediments. Active redox, microbial and thermolytic processes of organic matter transformation take place in the sedimentary mass. Special character of chromatographic spectra of n-alkane distribution in both low and high-molecular ranges, as well as increased naphtene contents can be interpreted as a sign of oil hydrocarbon generation from maternal organic matter as a result of thermocatalytic reactions within sedimentary mass and their displacement into the upper sedimentary layers. Molecular compositions and concentrations of phenols and lignin were determined in core samples from the Norwegian Sea. Total concentration of phenols in the cores ranges from 8.1 to 101.8 (µg/g of dry sediments that corresponds to 0.15-1.15% of TOC. Lignin concentration was estimated at 21.0-459.0 µg/g of dry sediments (0.59-7.9% of ?org. Phenol compounds of p-hydroxybenzoic, vanillin, syringyl and cinnamyl families as basic components of lignin macromolecules were identified. It was found that sea currents and aerosols are the main contributors of lignin into the abyssal part of the Norwegian Sea.

Maintenance of coelomic fluid pH in sea urchins exposed to elevated CO2: the role of body cavity epithelia and stereom dissolution

Experimental ocean acidification leads to a shift in resource allocation and to an increased [HCO3-] within the perivisceral coelomic fluid (PCF) in the Baltic green sea urchin Strongylocentrotus droebachiensis. We investigated putative mechanisms of this pH compensation reaction by evaluating epithelial barrier function and the magnitude of skeleton (stereom) dissolution. In addition, we measured ossicle growth and skeletal stability. Ussing chamber measurements revealed that the intestine formed a barrier for HCO3- and was selective for cation diffusion. In contrast, the peritoneal epithelium was leaky and only formed a barrier for macromolecules. The ossicles of 6 week high CO2-acclimatised sea urchins revealed minor carbonate dissolution, reduced growth but unchanged stability. On the other hand, spines dissolved more severely and were more fragile following acclimatisation to high CO2. Our results indicate that epithelia lining the PCF space contribute to its acid-base regulation. The intestine prevents HCO3- diffusion and thus buffer leakage. In contrast, the leaky peritoneal epithelium allows buffer generation via carbonate dissolution from the surrounding skeletal ossicles. Long-term extracellular acid-base balance must be mediated by active processes, as sea urchins can maintain relatively high extracellular [HCO3-]. The intestinal epithelia are good candidate tissues for this active net import of HCO3- into the PCF. Spines appear to be more vulnerable to ocean acidification which might significantly impact resistance to predation pressure and thus influence fitness of this keystone species.

(Table 1) Composition of organic matter in bottom sediments from the Kuril-Kamchatka Trench

From results of analyses of sediment samples collected on a profile crossing the Kuril-Kamchatka Trench distribution of organic D, N. carbohydrates, lipids and humic substances was established, as well as nature of their relationship with amorphous silica and clay fraction. Sum of the main biochemical groups of organic matter in the surface layer of sediments (0-1 cm) from the Kuril-Kamchatka Trench amounts to about 15%; neogenetic forms not encountered in living organisms make up 85% of organic matter. Among such forms 26% comprise humic substances formed during initial stages of polymerization of decomposition products of biochemical macromolecules.