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91.
92.
The major immunostimulatory principle in the hot aqueous extract of Chlorella pyrenoidosa has been isolated by a sequence of ethanol precipitation, precipitation with a cationic surfactant (CTAB), size exclusion chromatography, and anion exchange chromatography. A series of phosphorylated polysaccharides were obtained having different molecular masses but with similar structures. The higher molecular mass fractions showed considerable activity in the stimulation of mouse peritoneal macrophages to synthesize nitric oxide. The structure of the major polysaccharide was established by sugar analysis, configurational analysis, and 1D and 2D NMR experiments at 500 and 800 MHz on the parent polysaccharide, the de-O-acetylated polysaccharide, and on the components obtained after hydrolysis of the phosphate diesters. It had a β-d-Galp-(1→3)-β-d-Galp-(1→3)-backbone with half of the Galp units substituted at O-6 by terminal β-d-Glcp units. The remaining Galp units were substituted on O-6 by about equal amounts of α-d-Manp-1-phosphate and 3-O-Me-α-Manp-1-phosphate diesters. The substituents were not located in a regularly alternating fashion on the backbone. The O-acetyl groups were largely located on O-2 and O-4 of Galp and 35% of the Galp residues were O-acetylated. This is the second observation of a phosphorylated polysaccharide in an alga and the first where it is present to a significant extent. 相似文献
93.
MUBINA BEGUM NAUSHABA KHATOON 《Botanical journal of the Linnean Society. Linnean Society of London》1992,108(3):239-252
BEGUM, M. & KHATOON, N., 1992. Contribution to the taxonomy of the Ectocarpales (Phaeophyceae) from the coast of Karachi (Pakistan). The taxomony and ecology of five species belonging to the order Ectocarpales, representing three genera– Ectocarpus with one species, Hincksia with three species and Nemacystus with one species–are studied and reported as new records for the coast of Karachi, Pakistan. 相似文献
94.
The ultrastructure of the early stages of carposporophyte development in the marine red algaChondria tenuissima has been studied. The diploid carposporophyte grows on the gametophyte. Apical gonimoblast cells develop into diploid carpospores.
The basal gonimoblast cells cease to divide and undergo considerable cytoplasmic changes before they become incorporated into
the expanding fusion cell. Nucleus and plastids degenerate gradually, while mitochondria remain intact. The smooth endoplasmic
reticulum becomes prominent, it seems to produce small vesicles with electron dense contents. Simultaneously, numerous mucilage
sacs are formed, presumably from dilating ER cisternae. The contents of the mucilage sacs are secreted by exocytosis. The
pit connections between gonimoblast cells flare out. They remain as isolated bodies without connection to a wall after fusion.
Secondary pit connections occur between vegetative gametophyte cells and sterile carposporophyte cells. There are three different
morphological types of pit connections. 相似文献
95.
The molecular weight of the genomes of the blue-green algaeAnacystis nidulans andAnabaena cylindrica have been estimated as 2.27×109 and 2.47×109 daltons respectively from the renaturation kinetics of DNA. Thus the genomes of these organisms are similar in size to that ofEscherichia coli K-12, (2.40×109 daltons) measured by the same technique. No evidence was obtained of repeated sequences in the DNA of the two blue-green algae. 相似文献
96.
E. Schnepf 《Plant Systematics and Evolution》1992,181(3-4):233-244
The thallus ofThorea ramosissima was studied electron microscopically. The cells of the medulla, the cortex and the assimilatory hairs differ not only in size and number of plastids and their equipment with thylakoids but also in cell wall structure, the number of mitochondria and the activity of the Golgi apparatus, with dictyosomes transforming complete cisternae into Golgi vesicles with mucilaginous contents in the outer region of the cortex. The pit connections have plugs with a distinct plate—like (not dome-like) outer cap layer. BecauseT. riekei was reported to have dome-like outer cap layers and because this character was the main reason to place theThoreaceae into theBatrachospermales (Pueschel & Cole 1982),T. riekei was reinvestigated, too. A distinct outer cap could not be detected. The reliability of pit plug structure as a taxonomic character and the taxonomic position ofThorea is discussed. 相似文献
97.
《Journal of biological education》2012,46(1):53-58
Eothen Film Loops: Digestion, Absorption and Distribution The set consists of 6 loops: ref 815/C1-6 Price: Standard 8 mm (silent) £7–75 each. Super 8 mm (silent) £6–50 each Film Loops for the Nuffield Advanced Biological Science Project Available from: Penguin Education Ltd, Harmondsworth, West Drayton, Middx UB7 8EP 相似文献
98.
B. J. B. Wood P. H. K. Grimson J. B. German M. Turner 《Journal of biotechnology》1999,70(1-3):175-183
Interest is growing in algae as sources of medicinal and other potentially useful compounds, as well as their use in fish rearing. We are interested in their production of polyunsaturated fatty acids (PUFA). Photoautotrophic growth gives the highest levels of unsaturation in the fatty acid pool, but biomass concentrations are low. Heterotrophy on sugars gives higher biomass but seems to give more saturation in the fatty acids. In freshwater algae acetate has proved to be a good carbon source for photoheterotrophic growth, giving a crop with reasonably high levels of PUFA. In addition it is possible to regulate acetic acid addition through the pH change as acetate is used up in a well-aerated system, so achieving high biomass yields in the presence of relatively low acetate concentration. When we attempted to extend this to marine algae (principally species used in fish farming), we found that acetic acid was ineffective or sometimes toxic to most species tested, even at high pH. However, glycerol stimulated growth in a number of the algae. We report on this stimulation, and on the fatty acid composition of the resulting algal crop, discuss the problems in regulating the addition of this metabolite to algal cultures, and speculate on applications in the production of other useful algal metabolites. We also show that some of these algae used in fish farming grow best when the salinity of the water is rather less than that found in standard sea water. 相似文献
99.
100.
For analyzing sustainability of algal biofuels, we identify 16 environmental indicators that fall into six categories: soil quality, water quality and quantity, air quality, greenhouse gas emissions, biodiversity, and productivity. Indicators are selected to be practical, widely applicable, predictable in response, anticipatory of future changes, independent of scale, and responsive to management. Major differences between algae and terrestrial plant feedstocks, as well as their supply chains for biofuel, are highlighted, for they influence the choice of appropriate sustainability indicators. Algae strain selection characteristics do not generally affect which indicators are selected. The use of water instead of soil as the growth medium for algae determines the higher priority of water- over soil-related indicators. The proposed set of environmental indicators provides an initial checklist for measures of algal biofuel sustainability but may need to be modified for particular contexts depending on data availability, goals of stakeholders, and financial constraints. Use of these indicators entails defining sustainability goals and targets in relation to stakeholder values in a particular context and can lead to improved management practices. 相似文献