The Seaweed Site: information on marine algae

Michael Guiry’s seaweed site is a source of general information on all aspects of seaweeds. Seaweeds are marine algae: saltwater-dwelling, simple organisms that fall into the somewhat outdated, but still useful, category of “plants”. Most of them are the green (about 1200 species), brown (about 1750 species) or red (about 6000 species) kinds illustrated on this page, and most are attached by holdfasts, which generally just have an anchorage function, although a particularly efficient one.

Source: http://www.seaweed.ie/index.html

Phaeophyceae: Brown Algae

Algae Forms Algae, Brown Algae, brown seaweeds, Fucus, Laminaria, Phaeophyceae, Saccharina, Sargassum muticum 0 Comment

Phaeophyceae: Brown Algae

Examples: Laminaria and Saccharina, Fucus, Sargassum muticum, brown seaweeds

Characteristics

Laminaria digitata The brown colour of these algae results from the dominance of the xanthophyll pigment fucoxanthin, which masks the other pigments, Chlorophyll a and c (there is no Chlorophyll b), beta-carotene and other xanthophylls. Food reserves are typically complex polysaccharides, sugars and higher alcohols. The principal carbohydrate reserve is laminaran, and true starch is absent (compare with the green algae). The walls are made of cellulose and alginic acid, a long-chained heteropolysaccharide.

There are no known unicellular or colonial representatives; the simplest plant form is a branched, filamentous thallus. The kelps are the largest (up to 70 m long) and perhaps the most complex brown algae, and they are the only algae known to have internal tissue differentiation into conducting tissue; there is, however, no true xylem tissue as found in the ‘higher’ plants.

Himanthalia elongata Most brown algae have an alternation of haploid and diploid generations. The haploid thalli form isogamous, anisogamous or oogamous gametes and the diploid thalli form zoospores, generally by meiosis. The haploid (gametangial) and diploid (sporangial) thalli may be similar (isomorphic) or different (heteromorphic) in appearance, or the gametangial generation may be extremely reduced (Fucales). The brown Giant Kelp Macrocystis pyrifera (above) is harvested off the coasts of California for feeding abalone. It used to be used for alginate extraction, but this now mostly comes from Atlantic Ascophyllum nodosum and Laminaria hyperborea. Alginates, derivatives of alginic acids, are used commercially for toothpastes, soaps, ice cream, tinned meats, fabric printing, and a host of other applications. It forms a stable viscous gel in water, and its primary function in the above applications is as a binder, stabilizer, emulsifier, or moulding agent. Saccharina japonica, formerly Laminaria, and other species of the genus are grown on ropes in China, Korea and Japan for food and alginate production. Undaria pinnatifida is also cultivated in Japan, Korea and China for production of Wakame, a valuable food kelp. Small amounts are also grown in Atlantic France for the European market.

About 16,000 tonnes of Ascophyllum nodosum (Feamainn bhuí in Irish, referring to the yellow colour in summer) are harvested each year in Ireland, dried and milled in factories at Arramara Teo., Cill Chiaráin (Kilkerrin), Co. Galway; and some 3,000 t of the resulting seaweed meal is exported and processed in Scotland for the production of alginic acid. Laminaria hyperborea stipes (sea rods) are harvested in Norway and used to be collected in drift in Scotland and Ireland. The rods are used for the manufacture of high-grade alginates. Other brown algae are used for the extraction of agricultural sprays (‘liquid seaweed extracts‘). These extracts are used at low concentrations on crops and their hormone-like activities are thought to be due to betaines, cytokinenins, etc.

There are about 1800 species of brown algae, and most are marine. In general, brown algae are larger and more species are found in colder waters. Virtually all the biomass worldwide comes from a relatively small number of species in the orders Laminariales and Fucales. The total wholesale value of dried brown algae worldwide collected in the wild or cultivated is less than $100 million dollars.

Source: http://www.seaweed.ie/algae/phaeophyta.html

Chlorophyta: Green Algae

Algae Forms Algae, Chlamydomonas, Chlorella, Green Algae, Green seaweeds, Spirogyra, Ulva 0 Comment

Examples: Chlorella, Chlamydomonas, Spirogyra, Ulva. Green seaweeds.

Characteristics: Green colour from chlorophyll a and b in the same proportions as the ‘higher’ plants; beta-carotene (a yellow pigment); and various characteristic xanthophylls (yellowish or brownish pigments). Food reserves are starch, some fats or oils like higher plants. Green algae are thought to have the progenitors of the higher green plants but there is currently some debate on this point.

Green algae may be unicellular (one cell), multicellular (many cells), colonial (living as a loose aggregation of cells) or coenocytic (composed of one large cell without cross-walls; the cell may be uninucleate or multinucleate). They have membrane-bound chloroplasts and nuclei. Most green are aquatic and are found commonly in freshwater (mainly charophytes) and marine habitats (mostly chlorophytes); some are terrestrial, growing on soil, trees, or rocks (mostly trebouxiophytes). Some are symbiotic with fungi giving lichens. Others are symbiotic with animals, e.g. the freshwater coelentrate Hydra has a symbiotic species of Chlorella as does Paramecium bursaria, a protozoan. A number of freshwater green algae (charophytes, desmids and Spirogyra) are now included in the Charophyta (charophytes), a phylum of predominantly freshwater and terrestrial algae, which are more closely related to the higher plants than the marine green algae belonging to the Chlorophyta (known as chlorophytes). Other green algae from mostly terrestrial habitats are included in the Trebouxiophyceae, a class of green algae with some very unusual features.

Asexual reproduction may be by fission (splitting), budding, fragmentation or by zoospores (motile spores). Sexual reproduction is very common and may be isogamous (gametes both motile and same size); anisogamous (both motile and different sizes – female bigger) or oogamous (female non-motile and egg-like; male motile). Many green algae have an alternation of haploid and diploid phases. The haploid phases form gametangia (sexual reproductive organs) and the diploid phases form zoospores by reduction division (meiosis). Some do not have an alternation of generations, meiosis occurring in the zygote. There are about 8,000 species of green algae, about 1,000 of which are marine chlorophytes and the remainder freshwater charophytes. Unfortunately, just because algae are green no longer means that they are related: two major aggregation of green algae, the Chlorophyta and the Charophyta have turned out not be remotely related to each other.

Commercial uses: Organic beta-carotene is produced in Australia from the hypersaline (growing in high salinity water often known as brine) green alga Dunaliella salina grown in huge ponds. Carotene has been shown to be very effective in preventing some cancers, including lung cancer. Caulerpa, a marine tropical to warm-temperate genus, is very popular in aquaria. Unfortunately, this has led to the introduction of a number of Caulerpa species around the world, the best-known example being the invasive species Caulerpa taxifolia.

Chlorella, a genus of freshwater and terrestrial unicellular green alga with about 100 species, is grown like yeast in bioreactors, where it has a very rapid life history. It may be taken in the form of tablets or capsules, or added to foods such as pasta or cookies. Taken in any form, it is said improve the nutritional quality of a daily diet. According to the Taiwan Chlorella Manufacturing Company the increase in processed and refined foods in the diet of modern man make Chlorella an important food supplement for anyone interested in better health.

?Source: http://www.seaweed.ie/algae/chlorophyta.html

Chemicals In The Algae Helps To Protect Against Malaria

Algae Medicals and Nutrition Products American Association for the Advancement of Science, Antimalarial medication, Fiji, Georgia Institute of Technology, Infectious disease, Malaria, National Institutes of Health, Plasmodium falciparum, Washington 0 Comment

Posted by SherwoodSue on February 22, 2011 0 Comment

Scientists have discovered a class of chemicals to algae that they say could be a new weapon in the fight against malaria.

Researchers at the Georgia Institute of Technology have discovered.That certain chemicals in the plant used to combat fungal diseases have features of malaria in humans.

If the results are confirmed, hopefully, will give physicians an important new drugs to treat the disease.Which kills over a million people around the world every year.

According to the Daily Mail. Malaria is caused by the parasite Plasmodium falciparum is spread by mosquitoes. The parasite has developed resistance to many antimalarial drugs.

But according to researchers from the class consisting of algae, bromophycolides call could be the answer to the looming crisis. Study author Dr. Julia Kubanek, said: “These molecules are promising avenues for the treatment of malaria.

” There are only a few left that are effective drugs against malaria in all regions of the world, so we hope that these molecules continue to promise that we develop as a leading pharmaceutical company.”The chemical has been tested in a laboratory in the fight against malaria and the next step try it in a mouse with the disease.

Source: http://www.freshnews4u.com/2011/02/chemicals-in-the-algae-helps-to-protect-against-malaria/