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R. Schopf - One of the best experts on this subject based on the ideXlab platform.
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Untersuchungen zum Aminosäurenstoffwechsel der Fichtennadeln fressenden Blattwespe Gilpinia hercyniae Htg. (Hym., Diprionidae)
Zeitschrift für Angewandte Entomologie, 2009Co-Authors: R. SchopfAbstract:Studies on the metabolism of amino acids in the spruce needle feeding sawfly Gilpinia hercyniae Htg. (Hym., Diprionidae) The concentrations of 17 soluble and protein bound amino acids in larvae without alimentary canal (3 populations, L3, L4-, L4L5- and old L5-instar larvae), in adult females before (Iv) and after (In) oviposition (fig. 2, 3) and in cocoons (K) and exuvies of 5th instar larvae (E) (tab. 3) were estimated. The concentrations of amino acids decrease during larval development and increase after metamorphosis (fig. 1). The larval and adult stages of these sawflies are characterized by typical patterns of amino acids. More than 30% of the protein in the old 5th instar larvae is used for synthesis of the cocoon, for which 75% of the protein consists of serine, glycine and alanine (fig. 4). The absolute amount of protein in a typical old larva increases during metamorphosis (tab. 3). Zusammenfassung Die Konzentrationen 17 loslicher und proteingebundener Aminosauren von darmfreien Larvenrestkorpern (3 Populationen: L3, L4-, L4, L5- und alte L5-Larven), Imagines vor (Iv) und nach (In) Eiablage, Kokons (K) und Exuvien (E) der L5-Larven von Gilpinia hercyniae wurden bestimmt. Mehr als 30% des Proteins der alten L5-Larven wird fur die Anlage des Kokon benotigt. 75% der Kokonproteine sind aus gly, ser und ala aufgebaut. Die am Ende der Frastatigkeit vorliegende Proteinmenge wird wahrend der Metamorphose leicht vermehrt.
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As to the food quality of spruce needles for forest damaging insects. 18. Resorption of secondary plant metabolites by the sawfly Gilpinia hercyniae Htg. (Hym., Diprionidae).
Journal of Applied Entomology, 2009Co-Authors: R. Schopf, C. MignatAbstract:The polar low-molecular compounds shikimic acid, pinitol, quinic acid, fructose, glucose, sucrose, picein, catechin and gallocatechin from ethanolic extracts of spruce needles and faeces of Gilpinia hercyniae Htg. (Hym., Diprionidae) larvae were detected as trimethylsilyl derivatives by gas chromatography (fig. 1) as well as by combined gas chromatography-mass spectrometry (figs. 2, 3) and estimated quantitatively (table 1). Further phenolic compounds extracted with 80% ethanol-H2O were measured colorimetrically (Folin- and vanillin-positive compounds, anthocyanidin formation), (table 1). By comparing the concentrations of the compounds in needles and insect faeces the resorptions of spruce needle compounds were calculated as relative (P, in %) and absolute (R, μg/mg dry matter eaten) values. Up to 40% of the spruce needle compounds resorbed by the sawfly larvae are secondary plant metabolites (shikimic acid, quinic acid, picein, catechin, gallocatechin, total phenolics). The typical plant metabolites shikimic acid, pinitol, quinic acid and catechin (as glucoside) were detected in the degutted larvae. As compared to quinic acid shikimic acid is metabolized more rapidly by the insects. With increasing age of the larvae the metabolism of shikimic acid, pinitol and quinic acid is accelerated. Phenolic spruce needle compounds are directed inter alia to tanning processes and thus the requirement for essential aromatic amino acids will be reduced. Catechin is stored as the glucoside in the larval silk glands and excreted as the aglucone for cocoon formation. In light cocoons as compared to dark ones significantly higher concentrations of free catechin and 80% ethanol soluble Folin-positive compounds were found (table 3). Furthermore light and dark cocoons could be differentiated by the pattern of the compounds after thin-layer chromatography (fig. 4). Zusammenfassung Zur Nahrungsqualitat von Fichtennadeln fur forstliche Schadinsekten. 18. Resorption sekundarer Pflanzenstoffe durch die Blattwespe Gilpinia hercyniae Htg. (Hym., Diprionidae) In athanolischen Extrakten aus Fichtennadeln und dem Kot der nadelfressenden Blattwespe Gilpinia hercyniae wurden die niedermolekularen polaren Verbindungen Shikimisaure, Pinitol, Chinasaure, Fructose, Glucose, Saccharose, Picein, Catechin und Gallocatechin als Trimethylsilyl-Derivate durch Gaschromatographie (Abb. 1) und Gaschromatographie-Massenspektrometrie (Abb. 2, 3) nachgewiesen und quantitativ bestimmt (Tab. 1). Weiterhin wurden in 80% athanol losliche phenolische Verbindungen kolorimetrisch (Folin- und Vanillin-positive Verbindungen, Anthocyanidinbildung) gemessen (Tab. 1). Aus dem Konzentrationsvergleich der Verbindungen in Fichtennadeln und im Larvenkot wurde die Resorption der Fichtennadelinhaltsstoffe durch das Insekt sowohl als relativer (P, in %) als auch als absoluter (R, μg/mg gefreassener Nadeltrockenmasse) Wert berechnet (Tab. 1). Bis zu 40% der von den Insektenlarven resorbierten Fichtennadelinhaltsstoffe sind sekundare Pflanzenstoffe (Gesamtphenole, Shikimisaure, Chinasaure, Picein, Catechin und Gallocatechin). In den darmfreien Restkorpern der Larven wurden die typischen pflanzlichen Verbindungen Shikimisaure, Chinasaure, Pinitol und Catechinglucosid identifiziert (Tab. 2). Shikimisaure wird von den Blattwespenlarven rascher metabolisiert als Chinasaure. Mit steigendem Larvenalter wird der Stoffwechsel von Pinitol, Shikimisaure und Chinasaure in den Insekten beschleunigt. Die nadelburtigen phenolischen Verbindungen fliesen z.T. in Gerbungsprozesse der Insekten und entlasten somit den Stoffwechsel der essentiellen aromatischen Aminosauren. Catechin wird von den Insekten glucosidiert in den Spinndrusen gelagert und als Aglucon wahrend der Kokonbildung ausgeschieden. In hellen Kokons der Blattwespen werden im Gegensatz zu dunklen deutlich grosere Mengen an freiem Catechin und loslichen Folin-positiven Verbindungen gefunden (Tab. 3). Helle und dunkle Kokons konnen weiterhin durch ihr Komponentenmuster im Dunnschichtchromatogramm voneinander unterschieden werden (Abb. 4).
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Zur Nahrungsqualität von Fichtennadeln für forstliche Schadinsekten
Zeitschrift für Angewandte Entomologie, 2009Co-Authors: R. SchopfAbstract:As to the food quality of spruce needles for forest damaging insects. 1. Intake and excretion of 14C-labeled compounds by larvae of Gilpinia hercyniae (Hym., Diprionidae) after feeding on radioactive spruce needles Twigs of Picea abies with 1–3 year old needles were radioactively labeled by photosynthesis two hours long in an atmosphere of 14CO2. The 14C-activity of the components investigated remains nearly constant between the 6th and 23rd hour after the pulse (fig. 1) During this period the labeled needles were fed to 20 days old larvae of Gilpinia hercyniae. The 14C-distribution of soluble neutral and acidic compounds, hydrolyzable neutral and acidic compounds, lipids, amino acids, and proteins in needles, bodies of the larvae without guts, and faeces was investigated (tab. 2). In addition to the total intake of soluble needle sugars by the larvae there are indications of a limited digestive decomposition of starch. The carbohydrates absorbed are mainly directed to the synthesis of one fraction of the larvae lipids (fig. 6). As to the molar composition in the larvae the protein bound amino acids serine, alanine, glycine, and glutamic acid were found in greater quantities than in the needles (fig. 7). Their carbon back-bone is partially synthesized from the absorbed needle sugars. For these transaminations proline, aspartic acid, valine, isoleucine, leucine, and lysine seem to be possible amino donors. The remaining α-keto acids were considered to be involved in the fuel supply of the larvae. Zusammenfassung Zweige von Picea abies mit 1- bis 3jahrigen Nadeln wurden durch eine 2stundige Photosynthese-periode unter 14CO2 radioaktiv markiert. Die 14C-Aktivitat blieb in den untersuchten Verbindungsklassen der Fichtennadeln zwischen der 6. und 23. Stunde nach dem pulse annahernd konstant (Abb. 1). Nach Verfutterung der Nadeln in diesem Zeitintervall an 20 Tage alte Larven von Gilpinia hercyniae wurde die Verteilung der 14C-Markierung auf losliche neutrale und saure Verbindungen, hydrolysierbare neutrale und saure Verbindungen, Lipoide, Aminosauren und Proteine in Nadeln, darmfreien Restkorpern der Larven und im Kot untersucht (Tab. 2). Neben der nahezu quantitativen Aufnahme der loslichen Zucker durch die Diprionidenlarven wurden Hinweise auf einen bedingten Abbau nadelburtiger Starke erhalten. Die resorbierten Kohlenhydrate wurden bevorzugt zur Synthese einer Fraktion der Larven-Lipoide verwendet (Abb. 4, Tab. 4). Hinsichtlich der molaren Zusammensetzung sind in der Larve im Vergleich zur Nadel die proteingebundenen Aminosauren Serin, Glycin, Alanin und Glutaminsaure angereichert (Abb. 5). Ihr Kohlenstoffgerust wird zum Teil aus den resorbierten Nadelzuckern synthetisiert. Fur diese Transamimerungen kommen als NH2-Donatoren Prolin, Asparaginsaure, Valin, Leucin, Isoleucin und Lysin in Frage.
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Zur Bedeutung des Inhaltsstoffmusters von Fichtennadeln für die Entwicklung phytophager Insekten1
Journal of Applied Entomology, 2009Co-Authors: R. SchopfAbstract:Patterns of spruce needle composition and development of phytophagous insects The development of the spruce needle feeding sawfly Gilpinia hercyniae Htg. (Hym., Diprionidae) correlates with a numerical index which is calculated from the concentrations of 8 spruce needle compounds. One term of this index shows an antagonistic relation between protein amino acids and shikimic and quinic acid. Detailed investigations proved that the protein digestion of G. hercyniae might be a possible target of the disturbing effect of the acids. The main part of the protons which were neutralized in the gut of G. hercyniae results from the dissoziation of shikimic and quinic acid. In vitro experiments show that increasing pH values accelerate the activity of the gut proteases. This influence of pH on protein digesting enzymes could be confirmed by in vivo studies, too. The results support the assumption that the needle index describes quantitatively the food quality of spruce needles. Zusammenfassung Die Entwicklung der Fichtennadeln fressenden Blattwespe Gilpinia hercyniae Htg. (Hym., Diprionidae) korreliert eng mit den Konzentrationen von 8 Fichtennadelinhaltsstoffen, die zu einem Index IN verrechnet wurden. In einem Term des Nadelindex erscheinen Shikimi- und Chinasaure als antagonistische Grosen zu den Proteinaminosauren. Kausalanalytische Untersuchungen ergaben, das ein moglicher Angriffspunkt fur eine storende Wirkung der Sauren die Proteinverdauung im Darm von G. hercyniae ist. 70–80% der Protonen, die von G. hercyniae wahrend der Nahrungspassage neutralisiert werden, resultieren aus der Dissoziation dieser beiden Sauren. In vitro-Untersuchungen zeigen, das die Proteasen-Aktivitat des Darmhomogenats mit wachsendem pH-Wert deutlich ansteigt. Die pH-Abhangigkeit der Proteasen kann auch in vivo bestatigt werden Die Ergebnisse stutzen die Annahme, das der Nadelindex eine Maszahl fur die Nahrungsqualitat der Fichtennadeln darstellt.
J. Lunderstädt - One of the best experts on this subject based on the ideXlab platform.
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Methodische Überlegungen zur Bestimmung der Nahrung als Abundanzfaktor für phytophage Insekten am Beispiel der Wechselwirkung zwischen Fichte und Gilpinia hercyniae (Hym., Diprionidae)1
Zeitschrift für Angewandte Entomologie, 2009Co-Authors: J. LunderstädtAbstract:Methodical considerations on the determination of food as a density factor for phytophagous insects with the example of spruce (Picea abies Karst.) and Gilpinia hercyniae (Hym., Diprionidae) It is proposed to consider the changes in population size of phytophagous insects in relation to their food by measuring the flow of nutrients that interconnects plant and animal. This flow of nutrients is discussed as an ecophysiological bond within the frame-work of a more general terminology of an ecosystem. It is demonstrated with the monophagous saw-fly Gilpinia hercyniae on spruce by interpreting some data on the protein transfer from the plant into the insect. Zusammenfassung Es wird vorgeschlagen, die Veranderungen in der Populationsgrose phytophager Insekten in Beziehung zu dem Nahrstoffflus zu sehen, der Pflanze und Tier verbindet. Dieser Nahrstoffflus wird als okophysiologische Bindung innerhalb des Gesamtrahmens einer allgemeineren Terminologie zum Okosystem diskutiert. Er wird an dem Beispiel der Blattwespe Gilpinia hercyniae an Fichte in Hinsicht auf den Proteintransfer von der Pflanze in das Insekt behandelt.
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Über Zusammenhänge zwischen dem Zuckerstoffwechsel bei Larven von Gilpinia hercyniae (Hym., Diprionidae) und dem Kohlenhydratgehalt ihrer natürlichen Nahrung, den Nadeln von Fichte (Picea abies Karst)1
Journal of Applied Entomology, 2009Co-Authors: J. Lunderstädt, U. Schwarz, K. N. DinishAbstract:On relationships between the catabolism of carbohydrates of larvae ofGilpinia her-cyniae(Hym. Diprionidae) and carbohydrate content of their natural food, the needles of spruce (Picea abies). The flow of carbohydrates from the spruce needle into catabolic products of the insect is followed indirectly with the example of Gilpinia hercyniae Htg. which eats only plant food in the larval stage. This is done by comparative analyses of the constituents of the needles and the faeces. The data thus gained are correlated to the in-vitro-activities of some important carbohydrate dissimilating enzymes as related to the age of the larvae. Attempts are made to explain a possible control of the population densities of insects on grounds of the food available.
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The food-value of spruce needles for forest insect pests. 2. Comparative biochemical analyses of spruce needles and the excreta of larvae of Gilpinia hercyniae Htg.
Journal of Applied Entomology, 2009Co-Authors: J. Lunderstädt, Gunda ClausAbstract:As to food quality of spruce needles for forest damaging insects. 15. Comparative studies on the development and the rates of intake of protein-amino acids of Gilpinia hercyniae-larvae feeding on the same branches of spruce under controlled and field conditions 13-, 19-, 22-, and 23 day old populations of the 100th generation of larvae of Gilpinia hercyniae which were reared under controlled conditions were divided into two groups. Each group was kept simultaneously on the same exactly defined branches of spruce under controlled and field conditions. Technical details of the caging under field conditions and of the analysis of amino acids with a large number of samples are described. The characteristics of the larval development (table 2) and of the rates of intake of protein-amino acids (fig. 3) were determined. Nine partial experiments showed that a very similar weight was reached by the larvae independent of the larval age at the beginning of the experiment and of the external conditions. Furthermore it was found that within every experiment the profiles of the graphically evaluated rates of intake for the individual amino acids as a funtion of time are similar for the partial populations kept under field- and laboratory conditions, respectively. Since the intervals of the sampling dates were chosen schematically (every 2nd day) and not proportionally to the time span of development the characteristic points of the profiles are compressed in the diagram of the laboratory data as compared to those of the field. Since genetically homogenous larval populations were used the similarity of the maximal weight gained and of the rates of intake of the protein amino acids in the simultaneous laboratory- and field experiments are considered to be due to the needle qualities. These are genetically fixed for the respective single trees, and their expression as related to the external conditions chosen in the experiments can be described by the rates of intake for the individual amino acids as a function of observation time. Zusammenfassung 13, 19, 22 und 23 Tage alte Larvenpopulationen der 100. Generation einer Laborzucht von Gilpinia hercyniae wurden zu jeweils gleichen Anteilen an demselben genau definierten Nadelmaterial von Fichte unter Labor- und Freilandbedingungen gehalten. Technische Einzelheiten der Zwingerung unter Freilandbedingungen und der Aminosaurenanalyse bei umfangreichem Probe-material werden beschrieben. Die Kenndaten der Larvenentwicklung (Tab. 2) und die Aufnahmeraten der Proteinaminosauren (Abb. 3) sind bestimmt worden. Es wird gefunden, das unabhangig vom Larvenalter und den Ausenbedingungen in allen neun Teilversuchen ein sehr ahnliches maximales Gewicht erreicht wurde und innerhalb der einzelnen Versuche zwischen den Varianten Freiland und Labor die Profile der graphisch ausgewerteten Aufnahmeraten fur die einzelnen Aminosauren als Funktion der Zeit ahnlich sind. Da die Intervalle der Probennahme schematisch (alle 2 Tage) und nicht proportional zur Entwicklungszeit gelegt wurden, erscheinen die Kennpunkte der Profile bei Laborhaltung gegenuber denen unter Freilandhaltung zeitlich gerafft. Auf Grund des Einsatzes von genetisch einheitlichem Tiermaterial wird die Ahnlichkeit des erreichten maximalen Gewichts wie der Aufnahmeraten der Proteinaminosauren im kombinierten Labor- und Freilandversuch auf Nadeleigenschaften zuruckgefuhrt, die fur die jeweiligen Einzelbaume genetisch festgelegt sind und deren Auspragung durch die Umweltbedingungen fur die im Versuch gegebenen Verhaltnisse mittels der Aufnahmeraten fur die einzelnen Aminosauren als Funktion der Beobachtungszeit beschreibbar ist.
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Steuerungsprinzipien für die ökophysiologische Bindung zwischen Waldbäumen und phytophagen Insekten1
Journal of Applied Entomology, 2009Co-Authors: J. LunderstädtAbstract:Principles controlling the physiological bond between forest trees and phytophagous insects The rates of intake of proteinbound amino acids as a function of the feeding period are determined comparatively by means of alteration of the major parameters: plant clone (spruce), species of the phytophagous insect (Gilpinia hercyniae, Lymantria monacha, L. dispar) and the environmental conditions (field, controlled temperature and photoperiod). On the basis of diagrams calculated and drawn by a computer a specific role of proline, phenylalanine, tyrosine, histidine and arginine is relevant for the control of mass-flux within the plant-insect system. Zusammenfassung Die Aufnahmeraten proteingebundener Aminosauren als Funktion der Fraszeit werden unter Abwandlung der wichtigsten Eingangsgrosen Pflanzenklon (Fichte), Phytophagenart (Gilpinia hercyniae, Lymantria monacha, L. dispar) und Ausenbedingungen (Freiland, kontrollierte Temperatur und Photoperiode) vergleichend bestimmt. Auf der Grundlage der computererrechneten und -aufgezeichneten Profile ergibt sich eine mogliche besondere Rolle von Prolin, Phenylalanin, Tyrosin, Histidin und Arginin bei der Steuerung des Masseflusses innerhalb des Systems Pflanze-Phytophage.
J. Rose - One of the best experts on this subject based on the ideXlab platform.
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© Crown Copyright The effect of variation in light and nitrogen on growth and defence in young Sitka Spruce
1998Co-Authors: D. Wainhouse, R. Ashburner, E. Ward, J. RoseAbstract:Spruce, Picea sitchensis, were subject to high and low light and high and low nitrogen treatments in a polyhouse experiment. The effect of treatments on growth, needle and resin duct size, water content and concentration of quantitative defences (resin and polyphenols), sugars and nitrogen in needles, stems and roots was determined. 2. Concentrations of resin, polyphenols and carbohydrates were higher in low nitrogen treatments as predicted by resource-availability models of defence and the changes were similar in all parts of the trees including roots and in tissues formed prior to experimental treatments. Variation in the relative concentration of resin and poly-phenols between tissues may indicate a defensive trade-off. The size of needle resin ducts was positively correlated with tree growth but no evidence for ‘structural’ limitation of resin concentration in needles was found. 3. Changes in concentration of quantitative defences did not appear to be the result of a direct trade-off with growth but reflected treatment-induced variation in the root/shoot ratio. Production of quantitative secondary chemicals may therefore be part of an integrated response of the trees to environmental stress. 4. Bioassays with Elatobium abietinum, Gilpinia hercyniae and the fungus Phacidium coniferarum showed that changes in needle size, the nutritional and water content of tissues and the balance between nutrients and secondary chemicals influenced performance of one or more of the organisms. Changes in the concentration of carbon-based secondary chemicals alone were, therefore, of only limited value in predicting susceptibility of Spruce to insects and fungi
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The effect of variation in light and nitrogen on growth and defence in young Sitka Spruce
Functional Ecology, 1998Co-Authors: D. Wainhouse, R. Ashburner, E. Ward, J. RoseAbstract:1. Young plants of a northern (Alaska) and southern (Oregon) provenance of Sitka Spruce, Picea sitchensis, were subject to high and low light and high and low nitrogen treatments in a polyhouse experiment. The effect of treatments on growth, needle and resin duct size, water content and concentration of quantitative defences (resin and polyphenols), sugars and nitrogen in needles, stems and roots was determined. 2. Concentrations of resin, polyphenols and carbohydrates were higher in low nitrogen treatments as predicted by resource-availability models of defence and the changes were similar in all parts of the trees including roots and in tissues formed prior to experimental treatments. Variation in the relative concentration of resin and polyphenols between tissues may indicate a defensive trade-off. The size of needle resin ducts was positively correlated with tree growth but no evidence for ‘structural’ limitation of resin concentration in needles was found. 3. Changes in concentration of quantitative defences did not appear to be the result of a direct trade-off with growth but reflected treatment-induced variation in the root/shoot ratio. Production of quantitative secondary chemicals may therefore be part of an integrated response of the trees to environmental stress. 4. Bioassays with Elatobium abietinum, Gilpinia hercyniae and the fungus Phacidium coniferarum showed that changes in needle size, the nutritional and water content of tissues and the balance between nutrients and secondary chemicals influenced performance of one or more of the organisms. Changes in the concentration of carbon-based secondary chemicals alone were, therefore, of only limited value in predicting susceptibility of Spruce to insects and fungi.
K. N. Dinish - One of the best experts on this subject based on the ideXlab platform.
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Über Zusammenhänge zwischen dem Zuckerstoffwechsel bei Larven von Gilpinia hercyniae (Hym., Diprionidae) und dem Kohlenhydratgehalt ihrer natürlichen Nahrung, den Nadeln von Fichte (Picea abies Karst)1
Journal of Applied Entomology, 2009Co-Authors: J. Lunderstädt, U. Schwarz, K. N. DinishAbstract:On relationships between the catabolism of carbohydrates of larvae ofGilpinia her-cyniae(Hym. Diprionidae) and carbohydrate content of their natural food, the needles of spruce (Picea abies). The flow of carbohydrates from the spruce needle into catabolic products of the insect is followed indirectly with the example of Gilpinia hercyniae Htg. which eats only plant food in the larval stage. This is done by comparative analyses of the constituents of the needles and the faeces. The data thus gained are correlated to the in-vitro-activities of some important carbohydrate dissimilating enzymes as related to the age of the larvae. Attempts are made to explain a possible control of the population densities of insects on grounds of the food available.
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Zur Nahrungsqualität von Fichtennadeln für forstliche Schadinsekten
Journal of Applied Entomology, 2009Co-Authors: K. N. DinishAbstract:As to food quality of spruce needles for forest damaging insects. 5. Studies on the starch splitting enzyme (Amylase) in larvae of Gilpinia hercyniae Htg. The starch splitting enzyme (Amylase) was demonstrated in larvae of Gilpinia hercyniae (Fig. 1). The biochemical properties such as substrate concentration, enzyme concentration, activation by Ca++ ions, inhibition by EDTA, pH optimum and sensitivity to temperature (Fig. 2, Tab. 2) were studied. The reaction products due to enzyme action were separated by paper chromatography and compared with standards (Fig. 3). The variation of enzyme activity in 6, 12 and 18 days old larvae was studied (Fig. 4). The results with reference to the various conditions which influence the activity and its variation due to the age of larvae were discussed with respect to other carbohydrate metabolising enzymes such as maltase, gluco- and fructohexokinase. Zusammenfassung Das starkespaltende Enzym (Amylase) wurde in Larven von Gilpinia hercyniae nachgewiesen und seine biochemischen Eigenschaften untersucht. Die Reaktionsprodukte nach Enzymeinwirkung wurden chromatographisch analysiert, die Abhangigkeit der Enzymaktivitat vom Larvenalter nachgewiesen. Die Stellung des Enzyms im abbauenden Kohlenhydratstoffwechsel wird diskutiert.
D. Wainhouse - One of the best experts on this subject based on the ideXlab platform.
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© Crown Copyright The effect of variation in light and nitrogen on growth and defence in young Sitka Spruce
1998Co-Authors: D. Wainhouse, R. Ashburner, E. Ward, J. RoseAbstract:Spruce, Picea sitchensis, were subject to high and low light and high and low nitrogen treatments in a polyhouse experiment. The effect of treatments on growth, needle and resin duct size, water content and concentration of quantitative defences (resin and polyphenols), sugars and nitrogen in needles, stems and roots was determined. 2. Concentrations of resin, polyphenols and carbohydrates were higher in low nitrogen treatments as predicted by resource-availability models of defence and the changes were similar in all parts of the trees including roots and in tissues formed prior to experimental treatments. Variation in the relative concentration of resin and poly-phenols between tissues may indicate a defensive trade-off. The size of needle resin ducts was positively correlated with tree growth but no evidence for ‘structural’ limitation of resin concentration in needles was found. 3. Changes in concentration of quantitative defences did not appear to be the result of a direct trade-off with growth but reflected treatment-induced variation in the root/shoot ratio. Production of quantitative secondary chemicals may therefore be part of an integrated response of the trees to environmental stress. 4. Bioassays with Elatobium abietinum, Gilpinia hercyniae and the fungus Phacidium coniferarum showed that changes in needle size, the nutritional and water content of tissues and the balance between nutrients and secondary chemicals influenced performance of one or more of the organisms. Changes in the concentration of carbon-based secondary chemicals alone were, therefore, of only limited value in predicting susceptibility of Spruce to insects and fungi
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The effect of variation in light and nitrogen on growth and defence in young Sitka Spruce
Functional Ecology, 1998Co-Authors: D. Wainhouse, R. Ashburner, E. Ward, J. RoseAbstract:1. Young plants of a northern (Alaska) and southern (Oregon) provenance of Sitka Spruce, Picea sitchensis, were subject to high and low light and high and low nitrogen treatments in a polyhouse experiment. The effect of treatments on growth, needle and resin duct size, water content and concentration of quantitative defences (resin and polyphenols), sugars and nitrogen in needles, stems and roots was determined. 2. Concentrations of resin, polyphenols and carbohydrates were higher in low nitrogen treatments as predicted by resource-availability models of defence and the changes were similar in all parts of the trees including roots and in tissues formed prior to experimental treatments. Variation in the relative concentration of resin and polyphenols between tissues may indicate a defensive trade-off. The size of needle resin ducts was positively correlated with tree growth but no evidence for ‘structural’ limitation of resin concentration in needles was found. 3. Changes in concentration of quantitative defences did not appear to be the result of a direct trade-off with growth but reflected treatment-induced variation in the root/shoot ratio. Production of quantitative secondary chemicals may therefore be part of an integrated response of the trees to environmental stress. 4. Bioassays with Elatobium abietinum, Gilpinia hercyniae and the fungus Phacidium coniferarum showed that changes in needle size, the nutritional and water content of tissues and the balance between nutrients and secondary chemicals influenced performance of one or more of the organisms. Changes in the concentration of carbon-based secondary chemicals alone were, therefore, of only limited value in predicting susceptibility of Spruce to insects and fungi.