Marine alga organisms

Agar occurs as a cell-wall constituent of the red marine algae Rho ophyceae, from which it is extracted by hot water, and marketed as a dry powder, flakes, or strips. It dissolves in hot water and sets on cooling to a jelly at a concentration as low as 0-5%. Its chief uses are as a solid medium for cultivating micro-organisms, as a thickener, emulsion stabilizer in the food industry and as a laxative. 

Several analyses of known marine natural products according to the phylum of the source organism have revealed the richest sources of marine secondary metabolism (Figure It is clear from the data that marine algae and... 

The chloride anion is a major species in the oceans and plays an essential role in biochemistry. Compounds containing carbon-chlorine bonds occur much less frequently in nature. Volcanos emit some halocarbons, and marine algae generate chloromethane. Other marine species produce toxic organohalogen molecules that protect them from predators. Nevertheless, organic chlorine compounds are uncommon, and consequently there are few mechanisms that degrade them. 

Silver is a normal trace constituent of many organisms (Smith and Carson 1977). In terrestrial plants, silver concentrations are usually less than 1.0 mg/kg ash weight (equivalent to less than 0.1 mg/kg DW) and are higher in trees, shrubs, and other plants near regions of silver mining. Seeds, nuts, and fruits usually contain higher silver concentrations than other plant parts (USEPA 1980). Silver accumulations in marine algae (max. 14.1 mg/kg DW) are due mainly to adsorption rather than uptake bioconcentration factors of 13,000 to 66,000 are not uncommon (USPHS 1990 Ratte 1999). 

Zinc deficiency effects have been produced experimentally in freshwater sponges at <0.65 pg Zn/L (Francis and Harrison 1988), in rainbow trout fed diets containing <15 mg Zn/kg FW (Spry et al. 1988), in certain species of marine algae at <0.7 pg Zn/L (Vymazal 1986), and in certain species of marine invertebrates at <6.5 pg Zn/L (Clapper et al. 1985a, 1985b) or <34 mg Zn/kg DW whole organism (White and Rainbow 1985). Zinc deficiency in natural aquatic ecosystems has not yet been credibly documented. 

Schnitzler I, Boland W, Hay ME (1998) Organic sulfur compounds from Dictyopteris spp. deter feeding by an herbivorous amphipod (Ampithoe longimana) but not by a herbivorous sea urchin (Arbaciapimctulata). J Chem Ecol 24 1715-1732 Shen Y, T sai PI, Fenical W, Hay ME (1993) Secondary metabolite chemistry of the Caribbean marine alga Sporochnus bolleanus. a basis for herbivore chemical defense. Phytochemistry 32 71-75 Schupp PJ, Paul VJ (1994) Calcium carbonate and secondary metabolites in tropical seaweeds variable effects on herbivorous fishes. Ecology 75 1172-1185 Smit AJ (2004) Medicinal and pharmaceutical uses of seaweed natural products a review. J Appl Phycol 16 245-262... 

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