12.07.2015 Views

12th International Conference on Harmful Algae

12th International Conference on Harmful Algae

12th International Conference on Harmful Algae

SHOW MORE
SHOW LESS
  • No tags were found...

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

INTERNATIONAL SOCIETY FOR THE STUDY OF HARMFUL ALGAE12 th <str<strong>on</strong>g>Internati<strong>on</strong>al</str<strong>on</strong>g> <str<strong>on</strong>g>C<strong>on</strong>ference</str<strong>on</strong>g> <strong>on</strong> <strong>Harmful</strong> <strong>Algae</strong>, Copenhagen, Denmark, 4-8 September 2006technique and could be describedby Michaelis-Menten kinetics, whileurea uptake was related in a linearor sigmoid way to ureac<strong>on</strong>centrati<strong>on</strong> in the range 0.1 to 10µgat N/liter. The maximum uptakerate (Vmax) for amm<strong>on</strong>iumincreased over the day (3-6 h timescale) by a factor of 2-7 depending<strong>on</strong> species and strain. Halfsaturati<strong>on</strong>c<strong>on</strong>stants for amm<strong>on</strong>ium(KNH 4 ) did not show significantdifferences over time, but the KNH 4for the Olbia strain of A. catenellawere lower than those of theTarrag<strong>on</strong>a strain by factors of 2 to10. Another measure of affinity foramm<strong>on</strong>ium, the initial slope of theuptake rate – c<strong>on</strong>centrati<strong>on</strong>relati<strong>on</strong>ship, always increased overthe daylight period, indicating thatthose organisms are influenced bythe diel cycle through their capacityto absorb amm<strong>on</strong>ium at lowc<strong>on</strong>centrati<strong>on</strong>s. For urea, the uptakerate at 10 µgat N/l increased overtime <strong>on</strong>ly for the Olbia strain of A.catenella (by a factor of two). Thoseresults are discussed in terms of thec<strong>on</strong>tributi<strong>on</strong> of amm<strong>on</strong>ium and ureato the growth of thosedinoflagellates.PO.15-19The sampling technique greatlyaffects the toxin c<strong>on</strong>tent inDinophysis spp. cellsSessi<strong>on</strong>: PO.15 - M<strong>on</strong>itoringM Johansen 1 , T Rundberget 21 Marine Ecology, FISKEBÄCKSKIL,Sweden2 Nati<strong>on</strong>al Veterinary Institute, OSLO,NorwayThe toxin c<strong>on</strong>tent in cells ofDinophysis spp. is often measuredfrom c<strong>on</strong>centrated water samples.One reas<strong>on</strong> for this is thatDinophysis spp. normally appears inrelatively low numbers. In autumn2005, water samples were collectedusing a submersible pump.Samples were collected withoutc<strong>on</strong>centrati<strong>on</strong> and with ac<strong>on</strong>centrati<strong>on</strong> factor of 500 or 1000,using a plankt<strong>on</strong> net of 20-µm meshsize. Cell number per liter wasenumerated and toxin c<strong>on</strong>tent perliter was measured using LC-MS.The result was striking. Byc<strong>on</strong>centrating the samples, at leasttwo thirds of the toxin disappeared.The average cell toxin c<strong>on</strong>tent of D.acuminata in n<strong>on</strong>- c<strong>on</strong>centratedsamples was slightly over 100 pgOA/cell whereas c<strong>on</strong>centratedsamples <strong>on</strong>ly c<strong>on</strong>tained about 35 pgOA/cell. The same pattern of toxinloss was also found in cells of D.acuta and its c<strong>on</strong>tent of DTX-1 andDTX-2. These results str<strong>on</strong>glyemphasize that the handlingprocedure of the cells has a crucialeffect <strong>on</strong> the toxin c<strong>on</strong>tent in thecell. This has to be c<strong>on</strong>sideredwhen evaluating the toxicity ofDinophysis and its impact <strong>on</strong>mussel toxicity.PO.02-05Polyketide synthases in protists:a class of their ownSessi<strong>on</strong>: PO.02 - GenomicsUwe JohnAlfred Wegener Institut, BREMERHAVEN,GermanyPolyketides (PK) is a structurallydiverse class of natural products,including substances ofpharmaceutical, industrial andchemical ecological interest. PKexpress a number of human healthrelatedeffects (antibiotic, antitumor,and immunosuppressive agents)and many from marine microorganismsare potent biotoxins,which are involved in processessuch as chemical defence or200

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!