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  • 1
    Electronic Resource
    Electronic Resource
    Polyamine levels in pollinated and auxin-induced fruit of tomato (Lycopersicon esculentum) during development (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 87 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The changes taking place during fruit development in the concentration of the 3 polyamine fractions, i.e. free, perchloric acid-soluble conjugates and perchloric acid-insoluble bound polyamines, were analyzed in tomato fruits (Lycopersicon esculentum Mill, cv. F121) induced to set by either pollination or auxin application. Before the onset of cell division, total polyamines were 50% higher in auxin-treated fruits than in pollinated ones, most of the polyamines being found as perchloric acid-soluble conjugates in both fruit set treatments. At the onset the level of polyamines in both fruit types was 100 times higher than during cell expansion or ripening. The highest polyamine found during cell division was perchloric acid-soluble conjugated spermidine in both fruit set treatments. After cell division, polyamine concentration was similar in both fruit set treatments. The concentration of polyamines in the jelly was similar in pollinated and auxin-induced fruits during cell expansion but not during ripening. At the onset of ripening there was an increase of one order of magnitude in the concentration of perchloric acid-insoluble bound putrescine in the jelly of pollinated fruits. Polyamines were more than 5-fold higher in unpollinated ovaries than in fruits induced to set by either pollination or auxins. It is suggested that pollinated and parthenocarpic fruits differ in their polyamine metabolism during the initial stages of development, but not after cell division. It is also suggested that polyamines undergo rapid turnover during cell division. Perchloric acid-insoluble bound putrescine might play a role in seed formation in tomatoes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb08784.x
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of three carotenoid sources on growth and pigmentation of juvenile freshwater crayfish Cherax quadricarinatus (1998)
    Oxford UK : Blackwell Science Ltd
    Aquaculture nutrition 4 (1998), S. 0 
    Details
    ISSN: 1365-2095
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effect of adding carotenoids from various sources to feed of juvenile freshwater crayfish Cherax quadricarinatus on pigmentation, growth and survival was examined under laboratory conditions. Juvenile crayfish were fed diets fortified with carotenoids at a level of 100 μg g−1 for a period of either 49 or 55 days. Carotenoid sources were: dried algal cells prepared from Dunaliella salina in which the main carotenoid is β-carotene; a synthetic carotenoid, astaxanthin (Carophyll Pink 8%, manufactured by Hoffman–La Roche) and alfalfa meal. Crayfish receiving feeds fortified with carotenoids exhibited better body colouration than those in the control group, which were fed a diet to which no carotenoids were added. Growth and survival of the crayfish were not affected by the addition of carotenoids to their diet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2095.1998.00067.x
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  • 3
    Electronic Resource
    Electronic Resource
    Stress-induced ripening of the non-ripening tomato mutant nor (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 59 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tomato (Lycopersicon esculentum Mill.) plants of the non-ripening mutant nor (3rd backcross to the normal cultivar Rutgers) were grown under water stress induced in two different ways: a) reduction of water supply and b) increase in transpiration rate by adding kinetin to the nutrient solution. Both drought treatments induced fruits of the non-ripening mutant nor to ripen, that is, the parameters characteristic of ripening – red pigment, taste, pectolytic activity, softening, and the evolution rates of CO2 and ethylene – all increased, although not to the normal level. Such an increase does not normally take place in the nor mutant under control conditions. It is suggested that fruits of the nor mutant can be induced to ripen by any kind of water stress. The induction mechanism is still to be explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb00760.x
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  • 4
    Electronic Resource
    Electronic Resource
    Relationships among the herbicide and functional sites of acetohydroxy acid synthase from Chlorella emersonii (1993)
    Springer
    Planta 191 (1993), S. 1-6 
    Details
    ISSN: 1432-2048
    Keywords: Acetolactate synthase ; Chlorella (mutant) ; Imidazolinone ; Mutant (herbicide resistance) ; Sulfonylurea ; Triazolopyrimidine sulfonanilide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The properties of acetohydroxy acid synthase (AHAS, EC 4.1.3.18) from wild-type Chlorella emersonii (var. Emersonii, CCAP-211/11n) and two spontaneous sulfometuron methyl (SMM)-resistant mutants were examined. The AHAS from both mutants was resistant to SMM and cross-resistant to imazapyr (IM) and the triazolopyrimidine sulfonanilide herbicide XRD-498 (TP). The more-SMM-resistant mutant had AHAS with altered catalytic parameters (K m, specificity), but unchanged sensitivity to the feedback inhibitors valine and leucine. The second mutant enzyme was less sensitive to the feedback inhibitors, but had otherwise unchanged kinetic parameters. Inhibition-competition experiments indicated that the three herbicides (SMM, IM, TP) bind in a mutually exclusive manner, but that valine can bind simultaneously with SMM or TP. The three herbicide classes apparently bind to closely overlapping sites. We suggest that the results with C. emersonii and other organisms can all be explained if there are separate binding sites for herbicides, feedback inhibitors and substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240889
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  • 5
    Electronic Resource
    Electronic Resource
    Metabolic response of Chlorella emersonii to the herbicide sulfometuron methyl (1995)
    Springer
    Planta 197 (1995), S. 219-224 
    Details
    ISSN: 1432-2048
    Keywords: Acetohydroxy acid synthase ; Acetolactate synthase ; Ketobutyrate ; Chlorella ; Sulfonylurea ; Synchronized growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although it is clear that acetohydroxy acid synthase (AHAS; EC 4.1.3.18) is the target for sulfonylurea herbicides such as sulfometuron methyl (SMM), there is considerable uncertainty as to the mechanism(s) by which inhibition of AHAS inhibits or kills cells. We have further studied the mode of action of SMM, and its effects on metabolism and physiology in the unicellular green alga Chlorella emersonii var. emersonii. Addition of SMM to cells synchronized to a cycle of 16 h light-8 h dark showed that they were very sensitive to SMM toxicity in the first 16 h of the cell cycle, during which cell mass, protein and DNA increased. The increase in protein, DNA and chlorophyll was halted rapidly after SMM addition. Sulfometuron methyl prevented cell division even if added late in the light stages, when most of the protein and DNA were already synthesized, but did not affect cell division and autospore release if added after protein and DNA synthesis were complete. This suggests that SMM interferes with processes involved in preparation for division, beyond what would be expected if the cells were starved of the branched-chain amino acids needed as precursors for synthesis of proteins in general. The accumulation of α-ketobutyrate (αKB) in the cells in response to addition of SMM, and its possible role in the growth inhibition, was also investigated (in continually illuminated cultures). Intracellular αKB accumulated rapidly within 30 min of SMM addition, but declined nearly to basal levels in several hours. This paralleled the decrease and subsequent recovery of extractable AHAS activity. Despite this, growth of the algal culture did not recover. We suggest that metabolites formed by misincorporation of αKB in place of α-ketoisovalerate (e.g., in the ketopantoate hydroxymethyl transferase reaction) might be responsible for the persistence of growth inhibition. We note that an important difference between the effect of SMM and that observed with externally added αKB is that the ratio between intracellular αKB and α-ketoisovalerate is expected to be high in the first case, but not necessarily in the second.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202640
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  • 6
    Electronic Resource
    Electronic Resource
    The potential of production of sulfated polysaccharides from Porphyridium (1985)
    Springer
    Plant and soil 89 (1985), S. 117-127 
    Details
    ISSN: 1573-5036
    Keywords: Carrageenan ; Cell wall ; Marine algae ; Porphyridium ; Sulfated polysaccharides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The environmental conditions prevailing in Israel make marine algae an attractive crop for the production of valuable chemicals. A marine species of Porphyridium seems to fit this purpose. The unicellular red alga Porphyridium is encapsulated by a polysaccharide envelope that is present in the gel state. This polysaccharide is an acidic heteropolymer composed of sulfated sugars. It forms ionic bridges through divalent cations, thus reaching a very high molecular weight. The thickness of the polysaccharide capsule varies according to the phase of growth and the growth conditions. Its outer part dissolves in the growth medium, which becomes progressively more viscous. Sulfated polysaccharides form theramlly reversible gels similar to agar and carrageenan, which are usually extracted from marine macroalgae. These gels have been finding increasing use in commercial applications as gelling agents, thickeners, stabilizers, and emulsifiers. We have done experiments on the cultivation of a marine species of Porphyridium for the production of polysaccharides. This unicellular alga has an advantage over the macroalgae due to its relatively faster growth rate and the possibility to regulate its growth. The potential for production of the polysaccharide, both that dissolved in the external medium and that attached to the cell (including an intracellular fraction), and the effects of growth conditions on productivity were suudied in the laboratory. Porphyridium was also cultivated outdoors in seawater in 1-m2 ponds and its growth potential investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182238
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  • 7
    Electronic Resource
    Electronic Resource
    Light/dark cycles in the growth of the red microalga Porphyridium sp. (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 705-713 
    Details
    ISSN: 0006-3592
    Keywords: algal growth ; photobioreactor ; light/dark cycles ; photoinhibition ; airlift reactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of light/dark cycles on the growth of the red microalga Porphyridium sp. was studied in a tubular loop bioreactor with light/dark cycles of different frequencies and in two 35-L reactors: a bubble column reactor and an air-lift reactor. Photon flux densities were in the range of 50 to 300 μE m-2 s-1, and flow rates were 1 to 10 L min-1. Under conditions of low illumination and high flow rates, similar results were obtained for the bubble column and air-lift reactors. However, higher productivities - in terms of biomass and polysaccharide - were recorded in the air-lift reactor under high light intensity and low gas flow rates. The interactions of both photosynthesis and photoinhibition with the fluid dynamics in the bioreactors was taken as the main element that allowed us to interpret the differences in performance of the bubble column and the air-lift reactor. It is suggested that the cyclic distribution of dark periods in the air-lift reactor facilitates better recovery from the photoinhibition damage suffered by the cells. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:705-713, 1998.
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Extracellular polysaccharide production in outdoor mass cultures of Porphyridium sp. in flat plate glass reactors (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 269-275 
    Details
    ISSN: 1573-5176
    Keywords: areal productivity ; cell mass ; flat plate glass reactor ; light path ; polysaccharides ; Porphyridium ; red microalgae ; Rhodophyta ; viscosity ; volumetric productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This work concerns an attempt to develop large scalecultivation of Porphyridium sp. outdoors. Theimpact on cell growth and production of solublesulphated polysaccharides of light-path length (LP)was studied in flat plate glass reactors outdoors. TheLP of the plate reactors ranged from 1.3–30 cm,corresponding to culture volumes of 3–72 L. The sidewalls of all reactors were covered, ensuring similarilluminated surfaces for all reactors. Maximal daytemperature was maintained at 26 ±1 °C.Growth conditions of pH (7.5), stirring (withcompressed air) and mineral nutrients, were optimal.Maximal volumetric concentration of the soluble sulfated polysaccharide (1.32 g L-1) was obtained in winter with the smallest light-pathreactor (1.3 cm ) at a cell density of 1.37 ×1011cells L-1. Under these conditions, theviscosity of the culture medium was also highest,being inversely proportional to the culture'slight-path. Highest areal concentration of solublepolysaccharides (60 g m-2) and areal cell density(3.01 × 1012m-2) was recorded in the 20 cmLP reactor, progressively lower values being obtainedas the light path became shorter. A similar patternwas obtained for the areal productivity ofpolysaccharides, the highest being 4.15 g m-2day-1 (considering the total illuminated reactorsurface), produced in the 20-cm LP reactor.The main sugar composition (i.e. xylose, galactose andglucose) of the sulfated polysaccharides was similarin all reactors. As viscosity increased with timeduring culture growth, there was a substantial declinein bacterial population. Cultivation throughout mostof the year provided good evidence that a light pathlength of 20 cm in flat plate reactors under theseconditions is optimal for maximal areal solublepolysaccharide production of Porphyridium sp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008177002226
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  • 9
    Electronic Resource
    Electronic Resource
    Chickens fed with biomass of the red microalga Porphyridium sp. have reduced blood cholesterol level and modified fatty acid composition in egg yolk (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 325-330 
    Details
    ISSN: 1573-5176
    Keywords: red microalga ; Porphyridium sp. ; algal biomass ; feeding chickens ; polyunsaturated fatty acids ; egg yolk ; cholesterol ; triglycerides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biomass of the red alga Porphyridium sp.constitutes a unique combination of soluble sulfatedpolysaccharide that accounts for about 70% of thealgal dry weight, and various polyunsaturatedfatty acids (PUFA) such as arachidonic andeicosapentaenoic acid (AA, 20:4 ω6 and EPA,20:5 ω3). In view of earlier results in ourlaboratory showing a reduction in serum cholesteroland triglyceride levels in rodents fed with red algalbiomass, we set out to examine the influence of algalbiomass as a feed additive on the metabolism ofchickens, with an emphasis on blood and eggcholesterol levels. For that purpose, lyophilizedalgal biomass was fed to 12–13, 30-week-old, WhiteLeghorn chickens for 10 days at a proportion of 5% or10% of the standard chicken diet. Twelve chickensfed with unsupplemented diet served as the control. No differences in body weight, egg number, and eggweight were found between the algal-fed chickens (atboth concentrations) and the control. However,chickens fed with algal biomass consumed 10% lessfood for both groups, and their serum cholesterollevels were significantly lower (by 11% and 28% forthe groups fed with 5% and 10% supplement,respectively) as compared with the respective valuesof the control group. Egg yolk of chickens fed withalgae tended to have reduced cholesterol levels (by10%) and increased linoleic acid and arachidonic acidlevels (by 29% and 24%, respectively). In addition,the color of the egg yolk was darker as a result ofthe higher carotenoid levels (2.4 fold higher) forchickens that fed with 5% supplement. Theseresults encourage the development of an improvedchicken feed having dietary fibers and polyunsaturatedfatty acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008102622276
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  • 10
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    Relationships among the herbicide and functional sites of acetohydroxy acid synthase from Chlorella emersonii (1993)
    Springer
    Details
    Publication Date: 1993-07-01
    Print ISSN: 0032-0935
    Electronic ISSN: 1432-2048
    Topics: Biology
    Published by Springer
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