Algae Nitzschia

Freshwater diatom, Nitzschia palea-, 5 pg/L Alga, Ochromonas danica... 

Cvejic JH, Rohmer M (2000) C02 as main carbon source for isoprenoid biosynthesis via the mevalonate-independent methylerythritol 4-phosphate route in the marine diatoms Phaeodactylum tricomutum and Nitzschia ovalis. Phytochemistry 53 21-28 de Nys R, Steinberg PD, Willemsen P, Dworjanyn SA, Gabelish CL, King RJ (1995) Broad-spectrum effects of secondary metabolites from the red alga Delisea pulchra in antifouling assays. Biofouling 8 259-271... 

Domoic acid (Fig. 28,80) (263) is a neuro-phycotoxin responsible for the mortality of wildlife and for amnesic shellfish poisoning (ASP) of humans during algal bloom. Domoic acid was first isolated from the red alga Chondria armata ( domoi in Japanese), and it is produced also by diatoms, such as Pseudo-nitzschia spp. For the latter, evidence has been presented that it is involved in iron acquisition (307). 

In addition to sulfoquinovosyldiacylglycerol, the marine diatom Nitzschia alba has been found to contain a sulfonium analog of phosphatidylcholine, phosphatidylsulfocholine (14). This lipid has two methyl groups attached to the sulphur atom, and it substitutes completely for phosphatidylcholine in Nitzschia alba. In other marine diatoms and algae, both lipids have been found (15). 

Figure 7.10. Production of bromomethanes by Antarctic ice algae (43) (NITZ 1.1 and 1.2 and NITZ 2.1 and 2.2 are sub-samples NITZ Nitzschia stellata, PORO Porosira pseudo-denticulata Atlantic data from (3)).

In the Eastern basin, 14 species of Bacillariophyta were found the dominant species were Amphora normanii, N. fonticola, Navicula spp., and Nitzschia communis (32, 18, 22, and 10% of total alga number, respectively). Chlorophyta was represented by only unidentified species. The total number of phytoplankton was 0.9 X 10 cells 1 and the biomass was 93 pg C... 

St. B-3 20.4 m 104.49 ppt 5.6°C Navicula phyllepta, Nitzschia fonticola Nitzschia liebetruthii At this station and deeper the ground was represented by white friable crystalline pulp ( an amorphous bottom ). Its top layer was occupied by algae... 

Even carbon atom normal olefins are significant components of the nonphotosynthetic diatom Nitzschia alba the n-Ci6 2 represents 33.8% of total n-alkanes + n-alkenes, the n-C,g 2 20.4%, the n-Cjg 2 9.3% (Tomabene et al., 1974). The predominance in Nitzschia alba of even-carbon numbered olefins, as compared with the high content of odd-carbon numbered olefinic hydrocarbons found in other algae is unique and suggests that this diatom may have an unusual biosynthetic pathway for hydrocarbons. 

Isodomoic acids A and B have previously been found in the red alga, C. armata, but have not been detected as major toxin components in Pseudo-nitzschia or in sheUflsh contaminated with DA from toxic diatoms. N. navis-varingica is the first diatom that was found to produce isodomoic acids A and B as major toxin components. 

Domoic acid is a naturally occurring excitatory amino acid that was identified as the toxin responsible for an outbreak of amnesic shellfish poisoning that occurred in Canada in 1987 following consumption of contaminated blue mussels (Mytilus edulis) [1] as well as numerous other outbreaks worldwide. The parent compound is a tricarboxylic amino acid produced by certain marine organisms, the best characterized of which are the red alga Chondria armata and the planktonic diatom Nitzschia pungens, although other species are also known to produce domoic acid (for review, see Reference 2). 

It is now recognized that at least five species of Pseudo-nitzschia are able to produce domoic acid under certain environmental conditions and, as described previously, monitoring of both alga and marker species for the appearance of domoic acid is increasingly common. Correspondingly, it is now apparent that the toxin enjoys a worldwide distribution and has been identified as either a food contaminant or a causative agent in marine wildlife toxicity events on a global scale. Some of the more well-documented outbreaks of domoic acid toxicity in wildlife are summarized in Table 20.4 and described briefly below. 

Hasle, G.R. (2002) Are most of the domoic acid-produdng spedes of the diatom genus Pseudo-nitzschia cosmopolites Harmful Algae, 1, 137-146. 

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