Hydrodictyon

Generally the most abundant sterol in higher plants is sitosterol which has a 24a-ethyl (Table 1), which accounts for about 50 to 80% of the total amount of plant sterols [16]. However, only seven species of 39 plants hitherto examined have been known to contain BRs with a 24a-ethyl and these are not major BRs except in the green alga Hydrodictyon reticulatum [18] (Tables 1 and 2). Furthermore, immature seed of Phaseolus vulgaris contains sitosterol as the major sterol (56% of the total sterol), however, corresponding BRs (28-homocastasterone and related BRs) were detected at very low levels [19]. On the other hand, campesterol and 24-methylene-25-methylenecholesterol each accounts for only about 3% of the total sterols. However, castasterone and 25-methyldolichosterone (and related BRs), which structurally correspond to these sterols, respectively, are major... 

Hi 24-Epicampesterol (Cjj) R2 24-Epicastasterone 24-Epibrassinolide Hydrodictyon reticulatum [18] Phaseolus vulgaris (seed) [28, 64] Orniihopus sativus (shoot/seed) [22,29] (4 species)... 

Hi Sitosterol (Cj,) fxfi R2 Homocascasterone Homobrassinolide Oryza sativa (seed-bran) [30] Brassica campestris (seed) [31] Hydrodictyon reticulatum [18] (7 species)... 

Putative precursor sterol Oryza Ornithopus Pisum Phaseolus Dolichos Lycopersicon Hydrodictyon... 

GDA DM http //hydrodictyon.eeb.uconn.edu/people/plewis/softwaie.php... 

Another impressive example is the appearance of Hydrodictyon in New Zealand where this very distinctive alga had never been seen before. It was found in a pond belonging to a hatchery supplying fish and aquatic plants to aquarists. Obviously, Hydrodictyon had been imported together with fish or aquatic plants from East Asia (Kristiansen, 1996). 

The macroalgae Hydrodictyon reticulatum are fed with the mineral and organic pollutants of the river they multiply at a high rate from April until October. Yields are 50-100 % higher in heated ponds than in non-heated ponds, and they amount to 12 to 18 tons dry biomass/ha.year in the climatic belgian conditions (i.e. 6-7 months culture). 

The composition of the dry Hydrodictyon biomass is presented in Table II. The high mineral content influences the ratio of the other components, when comparing to Scenedesmus. s is due to the excess of calcium carbonate in the river. The protein ofHydrodictyon is also valuable for animal feeding. Methane may be produced by anaerobic digestion from the raw biomass (Legros et al, 1982). 

The electrical potential difference across the membrane can be measured by placing appropriate electrodes on its two sides. To measure the potential across a cell membrane one electrode must be within the protoplast and preferably we should be able to ascertain whether it is in the vacuole or in the cytoplasm (since in one case it will be separated from the electrode in the external solution by tono-plast and plasmalemma and in the other only by the plasmalemma). To undertake such measurements very fine microelectrodes are needed electrodes have been used, the glass tips of which have a diameter of ca. 1 micron (/tm). Even with such electrodes large vacuolated cells rich in cytoplasm are needed, such large cells are also required to obtain adequate samples of vacuolar sap and of cytoplasm for accurate analysis of all their major ions, and for measurements of their ion fluxes. To meet these requirements experimenters have turned to the giant multinucleate cells of certain algae, notably species of Nitella, Hydrodictyon and Chora. 

Studies on Na efflux and K influx in the eells of the alga Hydrodictyon suggest that they have a sodium-potassium pump similar to that in animal cell membranes. It is suggested that in such a pump there is a single carrier which transports Na on its outward journey and K" on its inward journey. If this is so the Na" efflux should depend upon the external concentration indeed if there is no external the carrier should not be able to make its return... 

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