Navicula

B. striata, its secondary metabolic pattern, consisting of a series of uncommon polypropionates, is almost identical to that of its prey [36,37], On the contrary, if the mollusc, under maintenance in an aquarium, feeds on Haminoea navicula, it discharges [5] in the form of a yellow secretion two Haminoea metabolites, the haminols (8,9), structurally related to navenone-A (I), which possess alarm pheromone properties [38] for H. navicula. Studies on a third Aglajidae mollusc [39, 40], Philinopsis speciosa, led to the characterization of a 2-alkyl-pyridine, pulo upone (10), as a minor constituent co-occurring with two polypropionates closely related to the metabolites from the pair P. depicta-B. striata. 

In another study with rooted macrophytes, Navicula sp. and Elodea canadensis rapidly accumulated lead from solutions containing 1.0 mg Pb+2/L, i.e., 70 mg Pb/kg dry weight per minute the process was overwhelmingly passive (Everard and Denny 1985). Depuration was rapid 90% of the lead sorbed during the first hour by shoots of Elodea was released within 14 days after transfer to clean water, though 10% seemed to be irreversibly bound (Everard and Denny 1985). 

Giant kelp, Macrocystis pyrifera 2.0 mg/L Diatom, Navicula pelliculosa Photosynthesis inhibited 50% 4... 

HO, OH 1 ( Diatom - Navicula pelicullosa Component of a cell wall protein 242... 

Amino acids Navicula pelliculosa a b Melosira nummuloides a b Melosira granulata a b Cyclotella stelligera a b Cyclotella cryptica a b Nitzschia brevirostris a b Siliceous sponge Tissue Spicule ... 

Navicula petliculosa Melosira nummuloides Melosira granulata Cyclotella stelligera Cyclolella cryptk a Nitischia hrerirostris... 

Coombs, J., and Volcani, B. E. Studies on the biochemistry and fine structure of silica-shell formation in diatoms. Chemical changes in the wall of Navicula pelliculosa during its formation. Planta (Berl.) 82, 280-292 (1968). 

Cimino, G., Passeggio, A., Sodano, G., Spinella, A., and Villani, G., Alarm pheremones from the Mediterranean opistobranch Haminoea navicula, Experientia, 47, 61, 1991. 

More recently, structurally related metabolites have been found in Mediterranean cephalaspideans, that is, phenyl conjugated trienones, lignarenones A (54) and B (55) in the Cylichnidae Scaphander lignarius,125 and polyenic pyridines in the Haminoeidae haminols A (56) and B (57) in Haminoea navicula, haminol C (58) in H. orteai 26 121 Haminols A (56) and B (57) also induce alarm response at concentrations of 0.3 and 0.1 mg, respectively. Thus, navenones and their structural congeners may serve as a communication tool to indicate the presence of predators. 

Rao, V. N. R., and Gomathi, K. B. (1988). Uptake and assimilation of nitrogen by Navicula lucens Hustedt, a marine diatom. Acta Botanica Indica. 16, 131—142. 

Sullivan, C. (1976). Diatom minerahzation of sdicic acid. I. Si(OH)4 transport characteristics in Navicula pelliculosa. J. Phycol. 12, 390-396. 

Unsaturated and polyunsaturated isoprenoid hydrocarbons are prominent biochemicals in some diatom taxa such as Rhizosolenia, Haslea, Pleurosigma, and Navicula. 

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