Espen Hansen

Ecophysiological responses of Empetrum nigrum to heavy metal pollution.

Chlorophyll, organic (citric and malic acids) and abscisic acid (ABA) contents and stem water potential were measured to indicate possible physiological effects of heavy metal deposition on Empetrum nigrum L. (crowberry). The leaves and stems of E. nigrum were collected at distances of 0.5 and 8 km from the Cu-Ni smelter at Harjavalta, south-west Finland. All the investigated parameters were clearly affected by heavy metal emissions. Chlorophyll contents in the leaves and organic acid contents in the leaves and stems were lower close to the emission source. Generally found increase in organic acid contents with increasing Ni concentrations was not found, which might be due to the lower production of organic acids measured by decreased photosynthesis near the smelter. In contrast, ABA contents in stems and leaves in general, were higher in plants growing 0.5 km from the pollution source. Close to the smelter the stem water potential of E. nigrum was less negative during the day but more negative during the night. These results suggest that smelter emissions have a negative effect on the ecophysiology of E. nigrum even though it is considered to be a tolerant species to heavy metals.

Synoxazolidinones A and B: novel bioactive alkaloids from the ascidian Synoicum pulmonaria.

Bioassay-guided fractionation of the sub-Arctic ascidian Synoicum pulmonaria collected off the Norwegian coast led to the isolation of a novel family of brominated guanidinium oxazolidinones named synoxazolidinones A and B (1 and 2). The backbone of the compounds contains a 4-oxazolidinone ring rarely seen in natural products. The structure of the compounds was determined by spectroscopic methods. The synoxazolidinones exhibited antibacterial and antifungal activities.

A Combined Atomic Force Microscopy and Computational Approach for the Structural Elucidation of Breitfussin A and B: Highly Modified Halogenated Dipeptides from Thuiaria breitfussi

The use of atomic-force microscopy (AFM) with atomic resolution shows great potential for the structural characterization of planar, proton-poor compounds, as these compounds are prone to structural corrections. [1,2] Currently, AFM has limited ability to identify element type and consequently functional groups. Additional computational techniques, such as computer-aided structure elucidation (CASE) and the calculation of 13 C NMR shifts using electronic structure calculations (DFT) may assist in this respect. Herein we show the combined use of spectroscopic methods, AFM, CASE, and DFT to solve the structures of breitfussins A and B, which could not be solved using either method alone. The subject of this study was the Arctic hydrozoan Thuiaria breitfussi (Family Sertulariidae). The few publications on the chemistry of this family show the presence of sterols, [3] polyhalogenated monoterpenes, [4] and anthracenone derivatives. [5] Arctic marine environments support highly diverse and dense populations of marine invertebrates. [6,7] A

Gibberellins and Subapical Cell Divisions in Relation to Bud Set and Bud Break in Salix pentandra

Abstract. In young plants of Salix pentandra, a temperate zone deciduous woody species, elongation growth ceases and a terminal bud is formed at day lengths shorter than a critical length. This is the first step in dormancy development, making survival under harsh winter conditions possible. Early studies strongly indicate that gibberellin is involved in the photoperiodic control of bud set and bud break. GA1 action was studied by application under short days to plants where cessation of shoot elongation had occurred, followed by subsequent anatomic investigations of shoot tips. Under short days the frequency of cell division decreased rapidly along with the earlier observed decrease in GA1 levels. Application of GA1 to short-day–induced terminal buds rapidly stimulated cell division in apices several days before visible shoot elongation in response to this treatment was observed. One day after GA1 application a fourfold increase in cell division frequency in apices was observed, increasing to a maximum of sevenfold 2 days after application. Long-day treatment leading to induction of bud break after about 4–6 days was followed by slowly increasing frequency of cell divisions. In earlier studies of this species, short days and gibberellins had no effect on cell elongation. These data show that increased GA1 content, by application or long-day treatment, results in increased frequency of mitosis. This strongly indicates that GA1 affects stem elongation in connection with bud set and bud break primarily by affecting cell divisions in subapical tissues.

Anti-mitotic activity towards sea urchin embryos in extracts from the marine haptophycean Phaeocystis pouchetii (Hariot) Lagerheim collected along the coast of northern Norway.

The marine bloom-forming alga Phaeocystis pouchetii is suspected to produce some toxic compound responsible for reduced growth, fecundity and survival of other marine organisms. Sea urchin early development was used as a model to investigate the degree and nature of toxicity. Colonial cells of P. pouchetii were collected during its spring-bloom along the coast of northern Norway and maintained in culture for a short period of time in order to evaluate the concentration of toxic compounds present inside the cells or excreted to the surrounding seawater medium. Cells were harvested by filtration and toxins were extracted separately from the collected cells and the filtrate using organic solvents. We found that extracts from the filtered seawater at a concentration corresponding to 9.0 x 10(5) cells ml(-1) completely blocked cell divisions in embryos of the sea urchin Sphaerechinus granularis, whereas extracts from intact algal cells were only mildly cytotoxic. When the extracts from seawater culture medium were purified by RP-HPLC, cytotoxic activity towards S. granularis embryos was recovered in three consecutive fractions. Moreover, unfertilised eggs incubated in the active HPLC fractions became unproductive, whereas incubation of sperm gave a reduced fertilisation rate. This anti-proliferative effect was further characterized by immunofluorescence staining of sea urchin embryos. DNA labelling revealed that incubating sea urchin embryos in the purified algal extracts inhibited both pronuclei migration and fusion. Incorporation and detection of the DNA-base analogue 5-bromo-2-deoxyuridine showed that DNA-replication was blocked. Furthermore, staining of alpha-tubulin subunits demonstrated that embryonic tubulin organisation was altered. We conclude that P. pouchetii produce some anti-mitotic compound, and that senescent colonial cells to a great extent excrete this compound to their surroundings.

Bioactivity Screening of Microalgae for Antioxidant, Anti-Inflammatory, Anticancer, Anti-Diabetes, and Antibacterial Activities

Marine microalgae are considered a potentially new and valuable source of biologically active molecules for applications in the food industry as well as in the pharmaceutical, nutraceutical and cosmetic sectors. They can be easily cultured, have short generation times and enable an environmentally-friendly approach to drug discovery by overcoming problems associated with the over-utilization of marine resources and the use of destructive collection practices. In this study, 21 diatoms, 7 dinoflagellates and 4 flagellate species were grown in three different culturing conditions and the corresponding extracts were tested for possible antioxidant, anti-inflammatory, anticancer, anti-diabetes, antibacterial and anti-biofilm activities. In addition, for two diatoms we also tested two different clones to disclose diversity in clone bioactivity. Six diatom species displayed specific anti-inflammatory, anticancer (blocking human melanoma cell proliferation) and anti-biofilm (against the bacteria Staphylococcus epidermidis) activities whereas, none of the other microalgae were bioactive against the conditions tested for. Furthermore, none of the 6 diatom species tested were toxic on normal human cells. Culturing conditions (i.e. nutrient starvation conditions) greatly influenced bioactivity of the majority of the clones/species tested. This study denotes the potential of diatoms as sources of promising bioactives for the treatment of human pathologies.

The Antibacterial ent-Eusynstyelamide B and Eusynstyelamides D, E, and F from the Arctic Bryozoan Tegella cf. spitzbergensis

The brominated tryptophan-derived ent-eusynstyelamide B (1) and three new derivatives, eusynstyelamides D, E, and F (2-4), were isolated from the Arctic bryozoan Tegella cf. spitzbergensis. The structures were elucidated by spectroscopic methods including 1D and 2D NMR and analysis of mass spectrometric data. The enantiomer of 1, eusynstyelamide B, has previously been isolated from the Australian ascidian Eusynstyela latericius. Antimicrobial activities are here reported for 1-4, with minimum inhibitory concentrations (MIC) as low as 6.25 μg/mL for 1 and 4 against Staphylococcus aureus. Eusynstyelamides 2 and 3 showed weak cytotoxic activity against the human melanoma A 2058 cell line.

Light and temperature effects on bioactivity in diatoms

Isolates of five pelagic North Atlantic marine diatoms (Bacillariophyceae): Attheya longicornis, Chaetoceros socialis, Chaetoceros furcellatus, Skeletonema marinoi and Porosira glacialis were cultivated in large photobioreactors at two light and two temperature regimes to test if this affected bioactivity. We screened for bioactivity in assays representing five different therapeutic areas: diabetes II (PTP1b), cancer (melanoma cells, A2058), anti-oxidants (FRAP), immunomodulation (TNFa) and anti-infection (MRSA, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa). All the diatom strains showed activity in two or more assays. We detected differences in bioactivity both between species and within species cultivated with different light and temperature regimes. Our results demonstrate the potential for a more exhaustive exploitation of diatom metabolites that can be obtained by manipulation of the cultivation conditions.

Antioxidant and Anti-Inflammatory Activities of Barettin

In this paper, we present novel bioactivity for barettin isolated from the marine sponge Geodia barretti. We found that barettin showed strong antioxidant activity in biochemical assays as well as in a lipid peroxidation cell assay. A de-brominated synthetic analogue of barettin did not show the same activity in the antioxidant cell assay, indicating that bromine is important for cellular activity. Barettin was also able to inhibit the secretion of the inflammatory cytokines IL-1β and TNFα from LPS-stimulated THP-1 cells. This combination of anti-inflammatory and antioxidant activities could indicate that barettin has an atheroprotective effect and may therefore be an interesting product to prevent development of atherosclerosis.

Metabolic fingerprinting reveals differences between northern and southern strains of the cryptic diatom Chaetoceros socialis

Morphology and molecular phylogeny constitute the structural elements of diatom taxonomy. These approaches do not, however, give information on the functioning of taxa. Additional methods to serve a more integrated and wide-ranging taxonomy have therefore been called for. Metabolic fingerprinting is one approach used within the field of metabolomics, often applied in classification of samples. Here we apply metabolic fingerprinting in a taxonomic study of a cryptic diatom species. Strains of the cosmopolitan diatom Chaetoceros socialis from two geographical areas; the north-east Atlantic and Arctic and the Gulf of Naples, were cultivated at three different temperatures; 2.5, 8 and 13°C. The strains from the two different geographical areas exhibited different growth rates as well as different photosynthetic efficiencies. Algal extracts, collected at the end of the growth experiments, were analysed by Ultra-Performance Liquid Chromatography High Resolution Mass Spectrometry. The two groups of strains were separated by principal component analysis of their metabolic fingerprints. Analysis of the data revealed both qualitative and quantitative differences in metabolite markers. These phenotypic differences reinforce differences also found for morphology, phylogenetic markers and growth rates, and point at different adaptive characteristics in organisms living under different temperature regimes.