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Digitale Medien

Proteins and Polysaccharides In the Nutrition of Paramecium Multimicronucleatun (1980)

JOHNSON, W. H. ; BRENNAN, M. D. ; BERARD, D. K. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

The @journal of eukaryotic microbiology 27 (1980), S. 0

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ISSN: 1550-7408

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: SYNOPSIS. Paramecium multimicronucleatum has been cultured for 20 years on a medium of salts, vitamins, amino acids, fatty acids, ribosides, and stigmasterol plus a little nondialyzable fraction (NDF) of baker's yeast. Fractionations of NDF identified 2 essentials: (a) in a fraction 〈 100,000 daltons which contained much protein and replaceable by ovalbumin and (b) in a fraction of 〈 300,000 daltons; this fraction contained much polysaccharide, replaceable by glycogen, which is 〉 300,000 daltons. For 2 years now P. multimicronucleatum has grown well with ovalbumin and glycogen replacing NDF. Besides ovalbumin, concanavalin A satisfies the protein requirement; this lectin attaches to sugar residues in glycogen. Studies with a fluorescent dye, PGA-1A, a stilbene derivative, provides further evidence for the polysaccharide requirement. This dye attaches to polysaccharides; when added to glycogen, and this in turn is added to a culture containing ovalbumin, fluorescent blue vacuoles appear within 2–3 h. When dye + glycogen were added to a culture without ovalbumin, no fluorescent vacuoles were found. A protein appears involved in formation of food vacuoles; this fits the pattern for endocytosis described in recent reviews. Besides glycogen, mannan gave good growth. Dextrin and amylopectin gave only fair growth through 7 serial transfers; glucose, maltose and amylose did not sustain growth. Strain 51 of P. tetratrelia, which grows well in NDF medium, grows well when NDF is replaced with ovalbumin and glycogen.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1550-7408.1980.tb04272.x

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Digitale Medien

The relationship between stomatal conductance, transpiration rate and tracheid structure in Pinus radiata clones grown at different water vapour saturation deficits (1983)

WHITEHEAD, D. ; SHERIFF, D. W. ; GREER, D. H.

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 6 (1983), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Abstract. Stomatal conductance and needle water potential of P. radiata clones were measured after 2, 5 and 8 months on plants grown in controlled environment rooms with markedly different water vapour saturation deficits (D). Conductance was significantly lower at high D, but water potential differences between treatments were not significant. When trees were moved between treatments most of the changes in conductances occurred within 2 h, with residual changes after 24 h. Water potentials were not different 24 h after the trees were moved. The effects were completely reversible.Transpiration rates of individual trees were highest in the high D treatment and lowest in the low D treatment. They were not linearly related to D because of decreasing conductance with increasing D.Height growth, diameter growth and foliage areas were not significantly different between treatments. Tracheid lumen diameters tended to be larger in trees grown at higher D although treatment differences were not significant.There were significant clonal differences in shoot conductance and tracheid dimensions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/1365-3040.ep11589331

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3

Digitale Medien

Growth and recession of aquatic macrophytes on a shaded section of the River Lambourn, England, from 1971 to 1980 (1982)

HAM, STEPHANIE F. ; COOLING, D. A. ; HTLEY, P. D. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Freshwater biology 12 (1982), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: SUMMARY. The growth and recession of macrophytes on a shaded section of the R. Lambourn were documented by a mapping procedure. With the exception of Ranunculus spp., the changes in total cover did not indicate directly the pattern of growth and recession of the macrophyles. Analysis of gross changes, expressed as gains and losses on cover, indicated that colonization of gravel and silt by the dominant macrophyte, Berula erecta, did not vary seasonally. Colonization was at a constant rate of about 8% of the site each month throughout the year and this accounted for 50% of the total number of gains by Berula. Gains of Berula from Ranunculus showed an annual cycle with a maximum during the summer when Ranunculus was in recession. Gains of Berula from Callitriche spp. also varied annually but the maximum was during the autumn. Total losses of Berula were at a constant rate throughout the year but were to gravel and silt during the winter, to Ranunculus in spring and early summer and to Callitriche in late summer and autumn. Analysis of loss of Berula with time indicated that the position of the Berula carpet was constantly changing. The growth and recession of Berula could not be linked in a meaningful way to environmental variables. Callitriche and Ranunculus both showed an annual pattern of growth and recession. There was temporal separation of the two macrophytes with Ranunculus growing mainly in spring and early summer and Callitriche showing maximum growth in late summer and autumn, and some evidence of spatial separation. The observed differences between years in the growth of Callitriche could not be attributed to any of the environmental variables measured.Discharge was thought to be an important variable controlling the growth of Ranunculus since increase of Ranunculus in the spring was positively correlated with the mean discharge at that time. In years when discharge was low, the growth of Rununculus appeared to be restricted by shading from epiphytic algae which accumulated on the plant surfaces under these conditions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.1982.tb00600.x

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Digitale Medien

Soybean leaf urease: Comparison with seed urease (1983)

Kerr, P. S. ; Blevins, D. G. ; Rapp, B. J. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 57 (1983), S. 0

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ISSN: 1399-3054

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Soybeans, Glycine max (L.) Merr., from ureides for transport of nitrogen from the root nodule to the shoot. The most direct routes for ureide utilization include the degradation of ureide-derived urea to NH3 and CO2. Ureolytic activity was found in leaf disks of soybean and exhbited optimal activity at pH 7 in the presence of a high concentration of urea (250 mM). In vitro studies showed neither urea amidolyase nor urea dehydrogenase activity in soybean leaves and the ureolytic activity was characterized as urease. Several biochemical properties of soybean leaf urease were determined and compared to seed urease properties. Soybean leaf urease differed from that of seed in five ways: pH optima (5.25 and 8.75), apparent Km (0.8 mM), no inhibition by hydroxyurea, faster electrophoretic mobility and no cross-reactivity with soybean seed urease antibodies. The data suggest that urease is the primary urea metabolizing enzyme present in soybean leaves. The properties of soybean leaf urease support the conclusion that a unique isozyme of urease is present in leaf tissue.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb02297.x

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