Effects of elevated carbon dioxide on three grass species from montane pasture II. Nutrient uptake, allocation and efficiency of use

Agrostis capillaris L.⁴ Festuca vivipara L. and Poa alpinaL.were grown in outdoor open-top chambers at either ambient (340µmol mol^–1) or elevated (680 µmol^–1)CO² for periods from 79 to 189 d. Under these conditions thereis increased growth of A. caplllarls and P. alpina, but reducedgrowth of F. vivipara. Nutrient use efficiency, nutrient productivity(total plant dry weight gain per unit of nutrient) and nutrientallocation of all three grass species were measured in an attemptto understand their individual growth responses further andto determine whether altered nutrient-use efficiencies and productivitiesenable plants exposed to an elevated atmospheric CO₂ environmentto overcome potential limitations to growth imposed by soilfertility. Total uptake of nutrients was, in general, greater in plantsof A. capillaris and P. alpina (with the exception of N andK in the latter) when grown at 680 µmol mol^–1 CO₂.In F. vivipara, however, uptake was considerably reduced inplants grown at the higher CO₂ concentration. Overall, a doubling of atmospheric CO₂ concentration had littleeffect on the nutrient use efficiency or productivity of A.capillaris. Reductions in tissue nutrient content resulted fromincreased plant growth and not altered nutrient use efficiency.In P. alpina, potassium, magnesium and calcium productivitieswere significantly reduced and photosynthetic nitrogen and phosphorususe efficiencies were doubled at elevated CO₂ with respect toplants grown at ambient CO₂ F. vivipara grown for 189 d showedthe most marked changes in nutrient use efficiency and nutrientproductivity (on an extracted dry weight basis) when grown atelevated CO₂, F. vivipara grown at elevated CO₂ however, showedlarge increases in the ratio of non-structural carbohydrateto nitrogen content of leaves and reproductive tissues, indicatinga substantial imbalance between the production and utilizationof assimilate. Key words: Nutrient, allocation, nutrient use efficiency, grasses, nutrient productivity, elevated CO₂, cliniate change     

The Accumulation of Amino-acids by Fungi, with particular reference to the Plant Parasitic Fungus Botrytis fabae

A method is described for the assay of the uptake of amino-acidsfrom aqueous solution by fungus mycelia. The rate of uptakein Botrytis fabae was found to vary with the age of the fungus,the pH, and the concentration of the amino-acid. Both L- andD-isomers were accumulated, but the system had a greater affinityfor the L-isomer. Unsubstituted —NH₂, and —COOHgroups were necessary for the process, which was constitutiveand inhibited by uncouplers of oxidative phosphorylation. Competitionexperiments with several amino-acids suggest that one uptakeprocess is common to all. Although both peptides and amineswere accumulated they did not compete effectively with amino-acidsfor uptake.     

Cation Exchange Properties of the Cell Walls of Enteromorpha intestinalis (L.) Link. (Ulvales, Chlorophyta

The cell wall of Enteromorpha intestinalis (a marine alga) hasbeen found to behave as a weakly cross-linked cation exchangerin NaCl solutions from 0.1–1020 mMolal (0.1–1000mMolar). Anion adsorption could be described by Freundlich isothermsover this concentration range. The large anion, inulin carboxylate,was found to be a tracer of the anion free space of plant tissuesonly in salt solutions above 10 mMolal. The cell wall of Enteromorphahas a cation exchange capacity of about 2500 µ mol g^–1dry wt. (Na+ form). The cell wallvolume is a complex functionof p^H and the NaCl concentration. As a result, the cation exchangecapacity is only predictable on a dry weight basis. The fixednegative charges of the cell wall have a pK_a of2 in situ and1.75 in vitro, and seem to be a mixture of sulphate and carboxylsugar esters. The applicability of the Donnan equation to plant cell wallsis discussed. Interpretation of the cell wall as a single thermodynamicphase is shown to be inappropriate. A large proportion of thecell wall solution is unaffected by the fixed anions.     

The Movement of Organic Nitrogen Compounds in Plants: With two Figures in the Text

The hypothesis that the movement of organic nitrogen, like thatof carbohydrate, is governed by the prevailing concentrationgradients for the mobile compounds in the phloem has been testedby determining the effect on nitrogen distribution when normaltranslocation was interrupted by ringing in Pelargonium spp.and Vicia faba plants. Nitrogen compounds in the plant tissue were fractionated intoprotein, soluble protein, amide, amino-acid, peptide, nitrate,and ammonia nitrogen. The presence of short-chain peptides inthe extracts was confirmed by paper chromatography. Results showed that accumulation above the ringed zone was confinedto the soluble nitrogen fractions and that amino-acids and possiblypeptides were involved in translocation. The direction of movementmay be determined by the prevailing concentration gradientsof these compounds in the phloem tissue.     

Solute Regulation in the Euryhaline Marine Alga Enteromorpha prolifera (O. F. Mull) J. Ag.

Young, A. J., Collins, J. C. and Russell, G. 1987. Solute regulationin the euryhaline marine alga Enteromorpha prolifera (O. F.Mll) J. Ag.—J. exp. Bot. 38: 1298–1308. The physiological basis for salt tolerance has been studiedin the euryhaline alga Enteromorpha prolifera. Levels of inorganicions and organic (compatible) solutes have been measured. K⁺makes the major contribution towards the internal osmotic potentialof the cell, while Cl^– and, in particular, Na⁺ contentsare low. Levels of the organic solute ß-dimethylsulphonio-propionate(DMSP) are high but are fairly insensitive to changes in theexternal salinity. Levels of amino-acids, calcium, phosphateand sulphate contribute relatively little towards the internalosmotic potential of the alga. As salinity is altered there are marked changes in the tissuewater content and volume. These changes directly affect theconcentration of the osmotic solutes within the cell. In diluteseawaters there is an increase in turgor as there is littlechange in the internal solute content of the cell compared tovalues in normal sea water. Inorganic ions, in particular K⁺,and organic solutes are accumulated in concentrated seawaters,although concentrations greater than 2·00 x seawaterresult in a reduction in the internal osmotic potential of thecell, mainly through loss of K⁺. Key words: Enteromorpha, salinity, osmoregulation     

Biosorption Behavior of Ciprofloxacin onto Enteromorpha prolifera: Isotherm and Kinetic Studies

The studies aimed at the feasibility of using Enteromorpha prolifera for the removal of ciprofloxacin from aqueous solutions. Batch experiments were carried out for the biosorption of ciprofloxacin onto Enteromorpha prolifera. The factors affecting the biosorption process such as the initial concentration, dosage, pH and the contact time were studied. Enteromorpha prolifera exhibited a maximum biosorption capacity of 21.7 mg/g. The pseudo-second-order kinetic model described the ciprofloxacin biosorption process with a good fitting. The optimum pH of ciprofloxacin adsorbed by Enteromorpha prolifera was 10. Biosorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which implied a heterogeneous biosorption phenomenon.     

Effects of soil mechanical impedance on root and shoot growth of Lolium perenne L., Agrostis capillaris and Trifolium repens L.

A method was used for applying a uniform mechanical impedanceto plant roots using sand packed at different bulk densitieswith depth within each growth cylinder. In a growth experiment,replicate cylinders were packed with sand to give the followingmechanical impedances: 0.25 MPa penetration resistance (negligibleimpedance), 1.40 MPa (moderate impedance) and 2.30 MPa (severeimpedance). Seedlings of Lolium perenne L., Trifolium repensL. and Agrostis capillaris were grown for 23 d in each impedancetreatment and effects on both roots and shoots were studied.Severe mechanical impedance affected both root and shoot growthrates for all three species resulting in smaller leaves andshorter roots. For the grasses, the root-to-shoot ratio at harvestwas the same for all the treatments, but a delay in the initiationof both shoots and roots was observed in the severe mechanicalimpedance treatment. The results are discussed in relation tothe possibility that roots penetrating the impeding treatmentsmay have caused signalling that kept shoot and root growth insynchrony. Differences observed in the response to mechanicalimpedance of T. repens compared to the other two species maybe a function of differences in the physiology between mono-and dicotyledonous species. Key words: Mechanical impedance, Lolium perenne, Trifolium repens, roots, shoots     

Free Amino-acids in the Endosperm of the Developing Coconut (Cocos nucifera)

The free amino-acids in the sap flowing from the incised inflorescenceof the coconut palm (Cocos nucifera) and in the liquid and solidendosperm of the coconut at various stages of development (4–12months from the time of opening of the spathe) have been studiedby paper and ion-exchange chromatography. The chief amino-acids in the sap were in decreasing order ofmagnitude: glutamic acid, aspartic acid, glutamine, serine,and asparagine. Smaller amounts of threonine, alanine, -aminobutyricacid, proline, valine, arginine, and tryptophan were found,along with traces of tyrosine, ß-alanine, lysine,histidine, leucine, isoleucine, and methionine. The chief amino-acids in the liquid endosperm of the nut until6 months of age were alanine, glutamic acid, serine, valine,and proline with smaller amounts of asparagine, aspartic acid,glycine, threonine, leucine, isoleucine, and glutamine. Thealanine, glutamic acid, proline, and -aminobutyric acid contentsof the liquid endosperm increased greatly as the solid endospermwas laid down, ultimately forming about 75 per cent. of thetotal free amino-acids. Nineteen amino-acids were detected atthe 8–10-month stage. -Aminobutyric acid appears in the liquid endosperm soon afterthe solid endosperm commences to form, and increases strikinglythereafter. It was also found in the free amino-acids of thesolid endosperm at all stages of development. This amino-acidwas not found in the acid hydrolysate of coconut globulin. The free amino-acids in the solid endosperm were found to reflectqualitatively the free amino-acid composition of the correspondingliquid endosperm. In addition, ß-alanine, -aminobutyricacid, phenylalanine, and tryptophan were present in small amounts.Alanine, serine, glutamic acid, and -aminobutyric acid, increasedwith age of the nut while the others increased up to 6 monthsand then decreased, only traces being found at maturity exceptin the case of aspartic acid, proline, and threonine. Twenty-oneamino-acids were detected in the free amino-acids of the solidendosperm. The source of the free amino-acids in the liquid endosperm andthe possible use of these amino-acids for protein synthesisin the coconut are briefly discussed.     

Effects of Elevated Carbon Dioxide on Plant Biomass Production and Competition in a Simulated Neutral Grassland Community

Using open-top chambers, four prominent species (Lolium perenne,Cynosurus cristatus, Holcus lanatusandAgrostis capillaris) ofIrish neutral grasslands were grown at ambient and elevated(700 µmol mol^-1) atmospheric CO₂for a period of 8 months.The effects of interspecific competition on plant responsesto CO₂enrichment were investigated by growing the species ina four-species mixture. The results indicate that the speciesdiffer in their ability to respond to elevated CO₂. CO₂-enrichmenthad the largest effect on the biomass production ofH. lanatus,but substantial stimulations in biomass production were alsofound for the other three species. The CO₂-stimulation of biomassproduction forH. lanatuswas accompanied by increased tillering.In addition, reductions in specific leaf area were found forall species. Exposure to elevated CO₂increased the communitybiomass of the four-species mixture. This increase can be mainlyattributed to a significant increase in the biomass ofH. lanatusatelevated CO₂. No statistically-significant changes in speciescomposition of community biomass were found. However,H. lanatusdidincrease its share of community biomass at each of the harvests,with the other three species, mainlyL. perenne, suffering lossesin their shares at elevated CO₂. The results show that: (1)the species varied in their response to elevated CO₂; and (2)species composition in natural plant communities is likely tochange at elevated CO₂, but these changes may occur rather slowly.Much longer periods of exposure to elevated atmospheric CO₂maybe required to permit detection of significant changes in speciescomposition.Copyright 1998 Annals of Botany Company Carbon dioxide (CO₂) enrichment, competition, Lolium perenne,Cynosurus cristatus, Holcus lanatus, Agrostis capillaris, biomass, specific leaf area, tillering.     

The Analysis of the Alcohol-insoluble Nitrogen of Plants by Quantitative Procedures based on Paper Chromatography

Part I. The amino-acid composition of egg albumin, zein, edestin,cucumber (Cucumis) seed globulin, and squash (Cucurbita) seedglobulin has been determined by a quantitative paper chromatographicmethod. The chromatographic analyses account completely forthe amino-acid nitrogen of the protein hydrolysate as determinedby the Kjeldahl method. More complete analyses than hithertoof cucumber and squash seed globulin have been obtained. Theseanalyses can now be regarded as complete since histidine andtryptophane, which have not been determined chromatographically,have previously been reported. The two cucurbit seed globulinsanalysed closely resemble edestin, and evident differences betweenthese three on the one hand and zein on the other are referredto in the text. It is evident that the paper chromatographicmethod is applicable to the quantitative amino-acid analysisof the protein-N fraction of the plants as well as to the analysisof pure proteins. Part II. The analysis of the alcohol-soluble and insoluble fractions(hydro-lysate) of potato tubers of the variety ‘Sebago’has been carried out. Attention is drawn to differences whichexist between the samples and varieties which have been investigated,namely ‘King Edward’, ‘Sebago’, and‘Katahdin’. These differences relate particularlyto the relative proportion of soluble to insoluble nitrogen,to the amount of amides present in the soluble fraction, andto the ratio of asparagine to glutamine. There is no correlation between the relative proportions ofamino-acids as they exist free in the tuber and as they occurin the alcohol-insoluble (protein) fraction. Certain compounds(e.g. -aminobutyric acid) are present free in the tissue, butthey do not occur in the protein. Also the amides far exceedtheir possible occurrence combined in the protein. Proline especiallyis much more abundant in the combined than in the free state,and the ratios between the various free amino-acids are quitedifferent from those which apply to the protein. The latterdata suggest that the soluble compounds which occur free arenot directly combined as such to form protein. The utility of the quantitative procedure based on partitionchromatography on paper in the analysis of the alcohol-insoluble(protein) fraction of plants is, therefore, established.     

Effects of elevated CO2 concentrations on three montane grass species: III. Source leaf metabolism and whole plant carbon partitioning

Agrostis capillaris L.⁵, Festuca vivipara L. and Poaalpina L.were grown in outdoor open-top chambers at either ambient (340 3µmol mol^–1) or elevated (6804µmol mol^–1)concentrations of atmospheric carbon dioxide (CO₂) for periodsfrom 79–189 d. Photosynthetic capacity of source leaves of plants grown atboth ambient and elevated CO₂ concentrations was measured atsaturating light and 5% CO₂. Dark respiration of leaves wasmeasured using a liquid phase oxygen electrode with the buffersolution in equilibrium with air (21% O₂, 0.034% CO₂). Photo-syntheticcapacity of P. alpina was reduced by growth at 680 µmolmol^–1 CO₂ by 105 d, and that of F. vivipara was reducedat 65 d and 189 d after CO₂ enrichment began, suggesting down-regulationor acclimation. Dark respiration of successive leaf blades ofall three species was unaltered by growth at 680 relative to340 µmol mol^–1 CO₂. In F. vivipara, leaf respirationrate was markedly lower at 189 d than at either 0 d or 65 d,irrespective of growth CO₂ concentration. There was a significantlylower total non-structural carbohydrate (TNC) concentrationin the leaf blades and leaf sheaths of A. capillaris grown at680µmol mol^–1 CO₂. TNC of roots of A. capillariswas unaltered by CO₂ treatment. TNC concentration was increasedin both leaves and sheaths of P. alpina and F. vivipara after105 d and 65 d growth, respectively. A 4-fold increase in thewater-soluble fraction (fructan) in P. alpina and in all carbohydratefractions in F. vivipara accounted for the increased TNC content. In F. vivipara the relationship between leaf photosyn-theticcapacity and leaf carbohydrate concentration was such that therewas a strong positive correlation between photosynthetic capacityand total leaf N concentration (expressed on a per unit structuraldry weight basis), and total nitrogen concentration of successivemature leaves reduced with time. Multiple regression of leafphotosynthetic capacity upon leaf nitrogen and carbohydrateconcentrations further confirmed that leaf photosynthetic capacitywas mainly determined by leaf N concentration. In P. alpina,leaf photosynthetic capacity was mainly determined by leaf CHOconcentration. Thus there is evidence for down-regulation ofphotosynthetic capacity in P. alpina resulting from increasedcarbohydrate accumulation in source leaves. Leaf dark respiration and total N concentration were positivelycorrelated in P. alpina and F. vivipara. Leaf dark respirationand soluble carbohydrate concentration of source leaves werepositively correlated in A. capillaris. Changes in source leafphotosynthetic capacity and carbohydrate concentration of plantsgrown at ambient or elevated CO₂ are discussed in relation toplant growth, nutrient relations and availability of sinks forcarbon. Key words: Elevated CO₂, Climate change, grasses, carbohydrate partitioning, photosynthesis, respiration     

Some Constituents of Xylem Sap and their Possible Relationship to Xylem Differentiation

Bleeding sap of Actinidia chinensis and Betula populifolia andguttation fluidof Avena sativa were analysed for sugars, amino-acids,auxin, and certain enzymes. A wide range of amino-acids wasfound in all three. Auxin was not detected in the bleeding sap,but was present in Avena guttation fluid (5.1 µg IAA equivalent/l).‘IAA oxidase’, acid phosphatase, ribonuclease, deoxyribonuclease,and protease were detected in the bleeding sap and guttationfluid. The possibility that some of the substances found insap and guttation fluid are products of autolysing, differentiatingxylem cells in the roots is discussed.     

两种饵料条件下点篮子鱼幼鱼酶活力及其消化道菌群比较

以点篮子鱼(Siganus guttatus)幼鱼为研究对象,分别用人工饲料和浒苔(Enteromorpha prolifera)进行饲喂,采用高通量测序技术结合生化分析方法,系统对比两种饵料对点篮子鱼(Siganus guttatus)幼鱼肝脏及消化道相关酶活力和消化道菌群的影响。结果显示,浒苔组点篮子鱼幼鱼虽然生长性能低于人工饲料组,但其淀粉酶活性更高,点篮子鱼对浒苔有良好的摄食和消化能力,浒苔足以满足点篮子鱼生长的需求;此外浒苔组点篮子鱼幼鱼消化道碱性磷酸酶、超氧化物歧化酶活性均显著高于人工饲料组,表现出了更高的免疫和抗氧化能力。在两种饵料条件下,菌群多样性随消化道延伸呈上升趋势,点篮子鱼幼鱼消化道菌群组成与饵料有关,变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)为共有优势菌门;浒苔组消化道菌群整体多样性较饲料组高,组成结构更加丰富多样,有利于鱼类的生长。研究结果表明点篮子鱼摄食浒苔具有良好的可行性基础,生态价值显著,值得深入研究与推广。     

Thiol pools and glutathione redox ratios as possible indicators of copper toxicity in the green macroalgae Enteromorpha spp. from the Scheldt Estuary (SW Netherlands,Belgium) and Thermaikos Gulf (Greece,N Aegean Sea)

Defence mechanisms against Cu toxicity were examined in two dominant Enteromorpha species from two coastal water types. The macroalgae were collected at three locations in the eulittoral of the Scheldt Estuary (Netherlands, Belgium) and the Thermaikos Gulf (Greece). For 10 days E. prolifera (Scheldt) and E. linza (Thermaikos) were incubated in seawater media of different salinities: 6, 9, 23 psu and 25, 30, 35 psu, respectively. In one series, media were enriched with 100 μg Cu l-1; responses were compared with those in controls with no extra Cu added. Enteromorpha, which is frequently used as a monitor species for heavy metal contamination, had relatively high Cu tissue levels (0.5–3.8 μmol Cu gdwt-1). Cu levels in E. prolifera controls (Scheldt) decreased with salinity; this was not the case with Cu levels in E. linza controls (Thermaikos). During the 10-d incubation algal protein contents and tissue Cu were rather stable. In E. linza (Thermaikos) algal protein contents were significantly lower than those of E. prolifera (Scheldt), although there was no indication for nitrogen limitation in E. linza. E. linza also had much lower glutathione pools than E. prolifera. Only under acute Cu stress (metal addition) did E. prolifera synthesise metal-binding thiols (phytochelatins). Phytochelatin pools are not suitable as an indicator of the Cu levels in these algae. The glutathione redox ratio GSH:(GSH + 0.5GSSG) was used as an indicator of (Cu-induced) oxidative stress. In E. prolifera (Scheldt) this ratio decreased with algal Cu content (P <0.05), from ~0.5 to ~0.2. The average glutathione ratios in Enteromorpha from the Scheldt and Thermaikos showed some oxidative stress induction with increasing algal Cu contents, however more clearly if Cu was added. As this redox ratio can also be influenced by environmental factors such as irradiance and desiccation, it may not be useful as an indicator for Cu-induced oxidative stress in situ. This revised version was published online in September 2006 with corrections to the Cover Date.     

Some properties and amino acid sequence of plastocyanin from a green alga, Ulva arasakii

Plastocyanin was purified from a multicellular, marine green alga, Ulva arasakii, by conventional methods to homogeneity. The oxidized plastocyanin showed absorption maxima at 252, 276.8, 460, 595.3, and 775 nm, and shoulders at 259, 265, 269, and 282.5 nm; the ratio A276.8/A595.3 was 1.5. The midpoint redox potential was determined to be 0.356 V at pH 7.0 with a ferri- and ferrocyanide system. The molecular weight was estimated to be 10,200 and 11,000 by SDS-PAGE and by gel filtration, respectively. U. arasakii also has a small amount of cytochrome c6, like Enteromorpha prolifera. The amino acid sequence of U. arasakii plastocyanin was determined by Edman degradation and by carboxypeptidase digestion of the plastocyanin, six tryptic peptides, and five staphylococcal protease peptides. The plastocyanin contained 98 amino acid residues, giving a molecular weight of 10,236 including one copper atom. The complete sequence is as follows: AQIVKLGGDDGALAFVPSKISVAAGEAIEFVNNAGFPHNIVFDEDAVPAGVDADAISYDDYLNSKGETV VRKLSTPGVY G VYCEPHAGAGMKMTITVQ. The sequence of U. arasakii plastocyanin is closet to that of the E. prolifera protein (85% homology). A phylogenetic tree of five algal and two higher plant plastocyanins was constructed by comparing the amino acid differences. The branching order is considered to be as follows: a blue-green alga, unicellular green algae, multicellular green algae, and higher plants.     

Effects of elevated carbon dioxide on three montane grass species: I. Growth and dry matter partitioning

Upland grasslands are a major component of natural vegetationwithin the UK. Such grasslands support slow growing relativelystable plant communities. The response of native montane grassspecies to elevated atmospheric carbon dioxide concentrationshas received little attention to date. Of such studies, mosthave only focused on short-term (days to weeks) responses, oftenunder favourable controlled environment conditions. In thisstudy Agrostis caplllaris L.⁵, Festuca vivipara L. and Poa alpinaL. were grown under semi-natural conditions in outdoor open-topchambers at either ambient (340µmol mol^–1) or elevated(680µmol mol^–1) concentrations of atmospheric carbondioxide (CO₂ for periods from 79 to 189 d, with a nutrient availabilitysimilar to that of montane Agrostis-Fescue grassland in Snowdonia,N. Wales. Whole plant dry weight was increased for A. capillarisand P. alpina, but decreased for F. vivipara, at elevated CO₂.Major components of relative growth rate (RGR) contributingto this change at elevated CO₂ were transient changes in specificleaf area (SLA) and leaf area ratio (LAR). Despite changes ingrowth rate at 680 µmol mol^–1 CO₂, partitioningof dry weight between shoot and root in plants of A. capillarisand P. alpina was unaltered. There was a significant decreasein shoot relative to root growth at elevated CO₂ in F. viviparawhich also showed marked discoloration of the leaves and increasedsenescence of the foliage. Key words: Allometry, growth analysis, elevated CO₂, grasses     

浒苔遥感监测研究进展

浒苔大规模集聚形成的绿潮灾害是海洋生态系统主要生态环境问题之一,基于卫星遥感影像监测浒苔及其扩展动态已成为一种及时有效的手段。对国内外浒苔遥感监测方面文献进行归纳整理,认为光学遥感数据、多波段比值法是最常用的遥感数据和监测方法。对遥感监测浒苔机理进行了阐述,并对分类方法进行评价认为监督分类法解译精度不高。目前单波段阈值法和多波段比值法应用广泛,但在监测漂浮浒苔和混合象元解译存在不足。辐射传输模型法能有效提高信息解译的精度,但还处于起步阶段。遥感监测浒苔灾害的未来发展需要提高影像空间分辨率,深入研究监测方法,进行多种平台和多源遥感数据相结合,并由定性走向定量,从而建立健全遥感监测预警系统。     

Production of Cellulolytic Enzymes by Botryodiplodia theobromae, Pat.

Carboxymethylcellulase (CM-cellulase) and ß-glucosidaseactivities were induced in cultures of Botryodiplodia theobromae,Pat. Both growth of the fungus and CM-cellulase production werebetter with sodium nitrate as nitrogen source than with eitherammonium nitrate or ammonium chloride. Growth, per unit nitrogensupplied, was greater with glutamic acid and aspartic acid asnitrogen sources than with sodium nitrate; this was probablybecause the fungus utilized the carbon of these amino-acids.Most ß-glucosidase activity was formed with ammoniumchloride or ammonium nitrate as nitrogen source. Glucose inhibited the activity of ß-glucosidase markedly.Low glucose concentration (c. 0.003 M) stimulated CM-cellulaseactivity but concentrations above 0.05 M inhibited. The formationof both enzymic activities was repressed in the presence ofglucose. ß-glucosidase activity was more thermolabilethan that of CM-cellulase.     

Gibberellins as endogenous growth regulators in green and brown algae

Summary Gibberellin-like activity was detected in extracts from Enteromorpha prolifera (Chlorophyta) and Ecklonia radiata (Phaeophyta). Material eluted from chromatograms of extracts and active in dwarf maize also brought about growth responses in the species from which the extract had been made. The responses were similar to those brought about by gibberellic acid. It is concluded that gibberellins are normally involved in regulating growth in green and brown algae.