At the full LHC design luminosity of 1034cm−2s−1, there will be approximately 109 proton–proton interactions per second. The ATLAS level-1 trigger is required to have an acceptance factor of ∼10−3. The calorimeter trigger covers the region |η|⩽5.0, and φ=0 to 2π. The distribution of transverse energy over the trigger phase space is analysed to identify candidates for electrons/photons, isolated hadrons, QCD jets and non-interacting particles. The Cluster Processor of the level-1 calorimeter trigger is designed to identify transverse energy clusters associated with the first two of these. The algorithms based on the trigger tower energies which have been designed to identify such clusters, are described here. The algorithms are evaluated using an FPGA. The reasons for the choice of the actual FPGA being used are given. The performance of the FPGA has been fully simulated, and the expected latency has been shown to be within the limits of the time allocated to the cluster trigger. These results, together with the results of measurements made with real data into a fully configured FPGA, are presented and discussed.

The final Pre-Precessor Multi-Chip Module (PPrMCM) of the ATLAS Level-1 Calorimeter Trigger is presented. It consists of a four-layer substrate with plasma-etched vias carrying nine dies from different manufacturers. The task of the system is to receive and digitize analog input signals from individual trigger towers, to perform complex digital signal processing in terms of time and amplitude and to produce two independent output data streams. A real-time stream feeds the subsequent trigger processors for recognizing trigger objects, and the other provides deadtime-free readout of the Pre-Processor information for the events accepted by the entire ATLAS trigger system. The PPrMCM development has recently been finalized after including substantial experience gained with a demonstrator MCM.

The level-1 calorimeter trigger consists of three subsystems, namely the Preprocessor, electron/photon and tau/hadron Cluster Processor (CP), and Jet/Energy-sum Processor (JEP). The CP and JEP will receive digitised calorimeter trigger-tower data from the Preprocessor and will provide trigger multiplicity information to the Central Trigger Processor and region-of-interest (RoI) information for the level-2 trigger. It will also provide intermediate results to the data acquisition (DAQ) system for monitoring and diagnostic purposes. This paper will outline a readout system based on FPGA technology, providing a common solution for both DAQ readout and RoI readout for the CP and the JEP. Results of building a prototype readout driver (ROD) module will be presented, together with results of tests on its integration with level-2 and DAQ modules.

The architecture of the ATLAS Level-1 Calorimeter Trigger has been improved and simplified by using a common module to perform different functions that originally required three separate modules. The key is the use of FPGAs with multiple configurations, and the adoption by different subsystems of a common high-density custom crate backplane that takes care to make data paths equal widths and includes minimal VMEbus. One module design can now be configured to count electron/photon and tau/hadron clusters, or count jets, or form missing and total transverse-energy sums and compare them to thresholds. In addition, operations are carried out at both crate and system levels by the same module design.

Microsomal fractions from elicited chickpea cell cultures, roots and leaves in the presence of O2 and NADPH catalyse the 2′- and 3′-hydroxylations of the isoflavones formononetin and biochanin A. The enzymes were characterized as to their substrate specificity, cofactor requirements and inhibition by cytochrome P450 inhibitors. The activities, which are low or not measurable in non-elicited cultures, roots and leaves, are strongly induced upon biotic and abiotic elicitation. Their induction pattern, however, is different depending on the source of the microsomal fraction. Induction of the 2′-hydroxylation of formononetin precedes accumulation of the chickpea phytoalexin medicarpin by two to four hours. The role of 2′-hydroxylation of formononetin in medicarpin synthesis is discussed.

A yeast glucan elicitor causes the accumulation of the pterocarpan phytoalexins medicarpin and maackiain in chickpea (Cicer arietinum) cell suspension cultures established from seeds. A cell culture line from a chickpea cultivar resistant against its main fungal pathogen Ascochyta rabiei accumulates large amounts (944 nmol/g fr. wt.) whereas a cell culture line from a susceptible cultivar accumulates only low amounts (38 nmol/g fr. wt.) of the phytoalexins. This is consistent with differential accumulation of pterocarpan phytoalexins in intact plants [1]. The first reactions in the pterocarpan-specific branch of biosynthesis are hydroxylation of the isoflavone intermediate formononetin in position 2' or 3', catalyzed by microsomal cytochrome P-450 monooxygenases. Upon elicitation formononetin 2'-hydroxylase undergoes a strong transient induction in the cell suspension culture of the resistant cultivar, whereas in the cell culture from the susceptible cultivar it is only slightly induced. In both cell suspension cultures the induction of cinnamic acid 4-hydroxylase and of formononetin 3'-hydroxylase does not show a clear correlation with phytoalexin accumulation. Experiments with different elicitor concentrations confirm that formononetin 2'-hydroxylase is much more induced in cell cultures from the resistant cultivar than from the susceptible one. It is concluded that the massive difference in phytoalexin accumulation between cell suspension cultures from the resistant and susceptible cultivar is determined mainly by the differential induction of formononetin 2'-hydroxylase activity.

Plants possess sophisticated mechanisms to defend themselves against pathogenic microorganisms. In addition to various constitutively formed, preinfectional mechanisms, the wide range of active defence reactions is of greatest importance (Keen 1986; Collinge and Slusarenko 1987; Fritig et al. 1987). Such reactions are induced after perception of a chemical signal provided by the invading pathogen. The de novo synthesis and differential accumulation in the plant of antimicrobial phytoalexins (Bailey and Mansfield 1982) in incompatible and compatible plant — pathogen interactions play crucial roles in the specificity of host resistance (Dixon 1986; Wood 1986).

The extractable activities of thirteen enzymes of primary and secondary metabolism have been measured in chickpea (Cicer arietinum L.) cell suspension cultures after treatment with an elicitor from the fungus Ascochyta rabiei (Pass.) Lab. The cell culture, derived from the A. rabiei resistant cultivar ILC 3279, constitutively accumulated the isoflavones biochanin A and formononetin together with their 7-O-glucosides and the 7-O-glucoside-6″-malonates. After elicitor application the cells rapidly form the pterocarpan phytoalexins medicarpin and maackiain. Among the enzymes of primary metabolism only the glucose 6-phosphate dehydrogenase exhibited a significant increase in activity with a maximum four hours after application of the elicitor. In phenylpropane metabolism the activities of phenylalanine ammonia lyase and chalcone synthase were enhanced by the elicitor and exhibited highest levels after four hours. In contrast the chalcone isomerase activity was not influenced by the elicitor. A substantial enhancement occurred with the isoflavone 7-O-glucosyltransferase activity eight hours after elicitor application. The results suggest that in this cell culture the elicitor-induced biosynthesis of pterocarpan phytoalexins was accompanied with a rapid and transient increase of those enzyme activities which are located at branching points of related pathways, i.e. pentose phosphate cycle, general phenylpropane metabolism, flavonoid formation and isoflavone conjugation.

The specific malonylesterase from chickpea (Cicer arietinum L.), hydrolyzing biochanin A 7-O- glucoside-6″-O-malonate (BGM), has been purified to apparent homogeneity and characterized recently (Hinderer et al., Arch. Biochem. Biophys. 248, 570-578 [1986]). Its substrate specificity as well as the high molecular mass of the native enzyme were further investigated. The 5-deoxy- isoflavone conjugate corresponding to BGM, the formononetin 7-O-glucoside-6,,-O-malonate (FGM), was shown to be a substrate of the malonylesterase essentially as BGM. By contrast, methyl-BGM, a diester of malonic acid was a poor substrate. The purified enzyme completely lacked thioesterase activity with malonyl-CoA as substrate. The inability of the malonylesterase to hydrolyze synthetic acetyl or propionyl esters was further demonstrated with a highly sensitive fluorometric assay using esters of 4-methylumbelliferone. The enzyme-catalyzed hydrolysis of BGM was stimulated in the presence of dissociated carboxylic acids like citrate which was most effective at 30 mM and pH 7.5-8.0. The purified malonylesterase as well as the enzyme activity in crude extracts were totally excluded in gelchromatography with Ultrogel AcA 22. The enrichment of the enzyme activity in microsomal fractions gave strong evidence that the malonylesterase is membrane-bound in vivo. Stimulation of the enzyme activity in vitro by detergents indicates the presence of lipid material in the enzyme and the activity profiles obtained after sedimentation analyses suggest that purification of a distinct membrane-protein complex had been achieved.

The specific malonylesterase from chickpea (Cicer arietinum L.), hydrolyzing biochanin A 7-O- glucoside-6″-O-malonate (BGM), has been purified to apparent homogeneity and characterized recently (Hinderer et al., Arch. Biochem. Biophys. 248, 570-578 [1986]). Its substrate specificity as well as the high molecular mass of the native enzyme were further investigated. The 5-deoxy- isoflavone conjugate corresponding to BGM, the formononetin 7-O-glucoside-6,,-O-malonate (FGM), was shown to be a substrate of the malonylesterase essentially as BGM. By contrast, methyl-BGM, a diester of malonic acid was a poor substrate. The purified enzyme completely lacked thioesterase activity with malonyl-CoA as substrate. The inability of the malonylesterase to hydrolyze synthetic acetyl or propionyl esters was further demonstrated with a highly sensitive fluorometric assay using esters of 4-methylumbelliferone. The enzyme-catalyzed hydrolysis of BGM was stimulated in the presence of dissociated carboxylic acids like citrate which was most effective at 30 mM and pH 7.5-8.0. The purified malonylesterase as well as the enzyme activity in crude extracts were totally excluded in gelchromatography with Ultrogel AcA 22. The enrichment of the enzyme activity in microsomal fractions gave strong evidence that the malonylesterase is membrane-bound in vivo. Stimulation of the enzyme activity in vitro by detergents indicates the presence of lipid material in the enzyme and the activity profiles obtained after sedimentation analyses suggest that purifica­tion of a distinct membrane-protein complex had been achieved.

Microsomal fractions derived from suspension‐cultured chickpea (Cicer arietinum L.) cells induced for phytoalexin biosynthesis catalyzed the monohydroxylation of 4′‐methoxyisoflavones (biochanin A and formononetin) in the 2′‐ and 3′‐positions. The reactions depended on NADPH and molecular oxygen. Post‐microsomal supernatants or microsomes from non‐induced cells are without detectable activity in the hydroxylase assay. 4′‐Hydroxyisoflavones (genistein and daidzein) were not hydroxylated to any significant extent. The occurrence of these hydroxylases proceeds concomitantly with the accumulation of two pterocarpan phytoalexins, medicarpin and maackiain, by induced cell cultures. The results are discussed with regard to the biosynthetic sequences in the conversion of isoflavones to pterocarpans.

Chickpea Cicer arietinum L.) cell suspension cultures transferred into a medium containing yeast extract accumulate the phytoalexins medicarpin and maackiain. Concomitant with accumulation of the pterocarpans a new enzyme activity is induced which was characterized as NADPH:isoflavone oxidoreductase. Maximum enzyme activity was reached 16 h after transfer of cells and then activity rapidly declined. The soluble enzyme was partially purified and shown to catalyze the reduction of the isoflavone 2'‐hydroxyformononetin to the isoflavanone vestitone which is an intermediate in medicarpin biosynthesis. The enzyme data suggest that 2'‐hydroxylation is a prerequisite for the conversion of isoflavones to pterocarpans.

Protein extracts from roots of chickpea (Cicer arietinum L.) plants contained high esterase activity hydrolyzing malonate hemiesters of isoflavone 7-O-glucosides. Using 5,7-dihydroxy-4′-methoxyisoflavone (biochanin A) 7-O-glucoside-6″-malonate as a substrate, a specific malonylesterase was purified about 700-fold to near homogeneity. The purified enzyme possesses an extremely low enzyme activity with synthetic esterase substrates. Various putative nonspecific esterases, as tested with α-naphthylacetate, were removed during enzyme purification. The malonylesterase demonstrated a very high molecular mass in gel chromatography and in sedimentation analyses with sucrose gradients ($̆= 2 × 106). Analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresis pointed to a single subunit of 32,000. The catalyzed reaction showed a pH optimum at 7.5 and a temperature optimum between 30 and 35 °C. The apparent Km for biochanin A 7-O-glucoside-6″-malonate was (4.2 ± 1.2) × 10−4m. The malonylesterase was insensitive to the esterase inhibitors eserine and neostigmine (10−3m) as well as phenylmethylsulfonyl fluoride, paraoxon, and diisopropylfluorophosphate (10−4m). On the other hand enzyme activity was totally inhibited by Hg2+ ions (10−5m) and p-hydroxymercuribenzoate (10−4m), whereas iodoacetamide (10−6–10−4m) inhibited only partially. Di- and tricarboxylic acids strongly stimulated enzyme activity at 10−2m. These properties indicate that the malonylesterase from chickpea roots greatly differs from other known esterases. The possible biological function of the specific malonylesterase is discussed in relation to isoflavone conjugate metabolism in chickpea.

In mixing experiments with extracts derived from two cell lines of Daucus carota tissue cultures with and without chalcone synthase activity, strong inhibition of chalcone synthase (CHS) became obvious. This inhibition was due to the presence of a heatlabile protein in extracts from cells devoid of CHS activity. This protein was partially purified and identified as 3′-nucleotidase (EC 3.1.3.6). Inhibition was also observed in the presence of purified 3′-nucleotidase from Lolium multiflorum. The phosphate group in the 3′-position of adenosine, a part of the CoA thioester substrates of CHS, was hydrolyzed by this enzyme. The dephosphorylated form of malonyl-CoA was no longer a substrate, whereas 4-coumaryl-3′-dephospho-CoA as well as 4-coumaryl-CoA was still able to act as a primer for the CHS reaction. Further studies showed that malonyl-3′-dephospho-CoA was an efficient CHS inhibitor. On the other hand, CoA-SH lost its inhibitory activity after dephosphorylation in the 3′-position. These results are discussed with respect to the mechanism of chalcone synthesis.

Chalcone synthase (CHS) has been partially purified about 35-fold. Withdrawal of 2-mercaptoethanol after precipitation with ammonium sulfate led to higher stability during further purification steps. In order to determine CHS activity, two procedures [according to Schröder et al. (1979) Plant Sci. Lett. 14, 281-286] were applied. The radioactivity extracted with ethyl acetate from the assay mixture (total products) was compared to 14C-labeled flavanone purified by TLC. The activity of CHS increased with bovine serum albumin (BSA) or 2-mercaptoethanol in the assay. Both effects were synergistic, but BSA did not promote "side products" as 2-mercaptoethanol did. BSA (10 mg ml-1) and 2-mercaptoethanol (1.4 mM) were components of the standard assay. Under these conditions, the CHS from Daucus carota had different pH optima for naringenin formation (7.9) and eriodictyol formation (6.8). The apparent Km values were 0.6 microM for 4-coumaroyl-CoA (pH 7.9), 7.7 microM for caffeoyl-CoA (pH 6.8), and 3.0 microM for malonyl-CoA (pH 7.9). Substrate inhibition was observed with 4-coumaroyl-CoA (greater than 10 microM) and malonyl-CoA (greater than 50 microM). The inhibitory activity of various flavonoids and related compounds (100 microM) was investigated. Naringenin and naringenin-chalcone inhibited eriodictyol formation totally and naringenin formation by 50%. In contrast, eriodictyol and eriodictyol-chalcone inhibited only eriodictyol formation by 40%. It was shown that the inhibition with naringenin was fully uncompetitive. These in vitro data support the view that the true substrate of CHS in D. carota is 4-coumaroyl-CoA.

The central vacuole is the largest organelle of mature plant cells. The vacuole is a storage compartment for ions, metabolites, secondary products and hydrolytic enzymes involved in various degradative processes.

In carrot cells (Daucus carota L.), cultured in the presence of gibberellic acid, anthocyanin synthesis is blocked at the level of chalcone synthase. By feeding suitable precursors for anthocyanins (naringenin, eriodictyol, dihydroquercetin) biosynthesis of cyanidin glycosides can be restored. After addition of these substrates to the culture medium in the presence of gibberellic acid, the activity of chalcone synthase remained as low as in the control without precursors. The highest increase in anthocyanin content was achieved using dihydroquercetin as the added precursor. The time course of this supplementation showed a rapid response; within 4 h a substantial increase in anthocyanin could be observed. In contranst, the flavonol quercetin is not a precursor for cyanidin. The fact that naringenin was also accepted for cyanidin synthesis leads to the conclusion that hydroxylation in 3′-position of ring B in Daucus carota takes place at the flavonoid stage.

The extractable activities of PAL, chalcone synthase and chalcone isomerase of white and coloured petals of the inflorescence of the umbel of wild carr

10 B coating as neutron converter and a mixture of Argon/CO2 as the counting gas. Several 1D-Cascade detectors have already been tested at ILL and PSI with great success. The latest prototype with an active area of 20x20 cm 2 features for the first time a 2D-Readout. The successful operation of the complete detector system has been shown during the operation of the research reactor FRJ-2 at the experimental test site EKN. The 2D-CASCADE-Detector under investigation is equipped with a double-sided readout structure which is sandwiched between two GEM-foils on either side. The readout structure is a simple flexible printed circuit board. It essentially consists of 128 stripes in x- and 128-stripes in y-direction. The entire stack is sealed with a 10 B-coated drift electrode on either side. The two GEM-foils which are closest to the readout structure are operated in amplification mode at a gain of about 60. These GEM-foils are termed Gain-GEMs. All the other GEM-foils are operated in transparent mode, i.e. at a gain of 1. They are called Transfer-GEMs. The Gain-GEMs as well as the Transfer-GEMs are coated with Boron on one side only. This setup is depicted in Figure 1.