brown algae


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

brown algae:

see PhaeophytaPhaeophyta
, phylum (division) of the kingdom Protista consisting of those organisms commonly called brown algae. Many of the world's familiar seaweeds are members of Phaeophyta. There are approximately 1,500 species.
..... Click the link for more information.
.

Brown Algae

 

(Phaeophyta), a type of sporiferous plants, including 240 genera (1,500 species), of which three are freshwater, the rest marine. The thallus is olive green to dark brown because of the presence in the chromatophores of the special brown pigment, fucoxanthin (C40H56O6), which masks other pigments (chlorophyll a, chlorophyll c, xanthophyll, and beta-carotene).

Brown algae are varied in form and size, ranging from microscopic, branched threads to 40-meter plants. In higher brown algae (for example, Laminariaceae) differentiation of tissues and the development of conducting elements are observed. Multicellular fibers with a basal growth zone, absent in other algae, are characteristic of brown algae. The cell walls contain cellulose and specific substances—algin and fucoidin. There is usually one nucleus in each cell. The chromatophores are small and disclike. In some species of brown algae there are pyrenoids, which bear little resemblance to those of other algae. Colorless vesicles of fucosan, which has many properties of tannin, accumulate around the nucleus of the cell. Stored in the tissues of brown algae as reserves are mannitol (a polyatomic alcohol), laminarin (a polysaccharide), and more rarely, oil.

Brown algae reproduce sexually and asexually, rarely vegetatively. They usually have a sporophyte and a gametophyte, which alternate strictly in higher families (Laminariaceae and Desmarestiaceae). In Cyclosporeae the gametophytes develop on the sporophytes; in primitive brown algae (Ectocarpaceae, Chordaceae, Cutleriaceae, and others) the gametophyte or sporophyte may fall outside the cycle of development or appear once in several generations. The reproductive organs are unilocular or multilocular sporangia. The multilocular sporangium, which most often functions as a gametangium, is formed as one cell or a series of cells divided by septa into chambers, each containing one gamete or spore. Meiosis usually occurs in unilocular sporangia; in Dictyotaceae, it occurs in tetrasporangia. The sexual process is isogamous, heterogamous, or oogamous. The pear-shaped spores and gametes, usually with one eyelet, have two flagella on the side, one directed forward and one backward.

Brown algae are divided into three classes: Aplanosporophyceae (only Dictyotaceae), Phaeosporophyceae (heterogeneratae and isogeneratae, except for Dictyotaceae), and Cyclosporophyceae (Cyclosporeae). Brown algae are distributed in all seas, especially cold ones, where they form large growths. They are a source of alginic acids and their salts—alginates—as well as of fodder meal and a powder used in medicine which contains iodine and other microelements. Some brown algae are used as food.

REFERENCES

Kursanov, L. I. Burye i krasnye vodorosli. Moscow, 1927.
Zinova, E. S. Vodorosli laponskogo moria (burye). Vladivostok, 1929. (lzv. Tikhookeanskoi nauchno-promyslovoi stantsii, vol. 3, issue 4.)
Zinova, A. D. Opredelitel’ burykh vodoroslei severnykh morei SSSR. Moscow-Leningrad, 1953.

IU. E. PETROV

brown algae

[¦brau̇n ¦al·jē]
(botany)
The common name for members of the Phaeophyta.
References in periodicals archive ?
These results differ from other findings, where lower concentrations of polyphenols were found in red algae in comparison to brown algae (Jimenez-Escrig et al., 2001, 2012).
In this work, polysaccharides obtained from the green alga Ulva fasciata, and the brown algae Dictyopteris polypodioides, Fucus virsoides and Undaria pinnatifida, were the most active against the studied bacterial pathogens.
Only six of these species, the brown algae Stoechospermum marginatum, Sargassum swartzii, S.
The unique accumulation efficiency and tolerance to heavy metals can be attributed to the high content of alginate and fucoidan in the cell walls of brown algae and of sulfated polysaccharides in red algae, for which heavy metals show a strong affinity [21].
Emilin Renitta, "Brown Algae mediated synthesis, characterization of gold nano particles using Padina pavonica and their antibacterial activity against human pathogens," International Journal of PharmTech Research, vol.
This is extracted from a type of brown algae, a seaweed commonly used in food and medical applications.
phylum of the kingdom protista consisting of those organisms commonly called brown algae. Many of the world's familiar seaweeds are members of Phaeophyta.
Nan Fuchs, introduced me to Alginol, a potent, uniquely harvested and processed brown algae. I didn't have much experience with brown algae, but I trusted Dr.
Brown algae are the basic raw material for the production of sodium alginate.