Volume 49, Issue 5-6

UV-irradiation of sliced stem tubers of kohlrabi (Brassica oleracea var. gongylodes) followed by incubation for 4 days, resulted in the production of two new sulphur-containing indole phytoalexins, cyclobrassinone and 1 -methoxyspirobrassinin, whose structures were elucidated on the basis of spectroscopic data. Three known indole phytoalexins, spirobrassinin, methoxybrassitin and methoxybrassinin, and several m inor phytoalexin-like compounds not yet identified were also isolated. The accumulation of these indole phytoalexins was also induced by abiotic elicitation with CuCl 2 . Feeding both of L-[β-14C]tryptophan and L-[ 14 CH 3 ]methionine to UV-irradiated stem tuber tissue of kohlrabi indicated that the S-containing indole phytoalexins were biosynthesized from these amino acids.

The accumulation and distribution of characteristic secondary products in the different organs of an Aloe plant (A. succotrina Lam.) were studied by high performance liquid chromatography for the first time. In the leaves of the Aloe plant, only anthrone-C-glycosyls of the 7-hydroxyaloin type and, for the first time in plant material, the free anthraquinone 7-hydroxyaloeemodin were found. In contrast to previous reports on the distribution of secondary products in Aloe plants, anthrone-C-glycosyls were also detected in flowers, bracts and the inflorescence axis of the species examined. Aloesaponol I, a tetrahydroanthracene aglycone, was only present in the underground organs and in the stem. The 2-alkylchromone-C-glucosyl aloeresin B showed no specific occurrence as it was found in every type of organ. Based on these results and the findings of recent studies on Aloe roots and flowers, a distri­bution scheme of polyketide types in the Aloe plant was established. It suggests a separate and independent anthranoid metabolism for underground Aloe organs and stem on the one hand, and for leaves and inflorescence organs on the other hand. In the latter structures anthranoid metabolism seems to be additionally compartmentalized as the anthranoid pro­ files of inflorescence organs and leaves differ in two points relevant to anthranoid biosynthe­ sis: firstly, the occurrence of anthrone aglycones and secondly, the individual content of corre­sponding anthrone-C-glucosyl diastereomers.

Lipase (triacylglycerol acylhydrolase EC 3.1.1.3) from rape (Brassica napus cv. Ceres) was isolated from cotyledons of dark-grown seedlings. The enzyme was partially purified by poly­ ethylene glycol precipitation. Delipidation of the lipase with n-hexane was required prior to further purification by anion exchange chromatography and size exclusion chromatography. A purification factor of 337 was ultimately achieved and the purification process was moni­tored by SDS-PAGE. Here, at least two protein bands with molecular masses of 62 and 64 kD a respectively were found in the active fraction obtained by size exclusion chromatography. Sodium deoxycholate was found to stimulate the lipase activity, but appeared to cause aggregation of the enzyme. It was not possible to estimate the isoelectric point of the dialyzed rape lipase due to the high molecular mass of the aggregates. Two simple methods to detect lipase activity directly on polyacrylamide gel were applied. No esterase activity was found by using p-nitrophenyl acetate as substrate.

Chitosan derivatives classed into three groups according to their molecular size were examined for the relationships between degree of N -acetylation and phytoalexin (+)-pisatin-inducing activity in pea epicotyl assay. Partially N-deacetylated chitin with degree of N-acetylation 56% (DAC 56%) was the most potent inducer of (+)-pisatin among sparingly water-soluble polysaccharides including chitosan (degree of N -acetylation 0%), DAC 32%, and chitin. Among the intermediate-sized molecules obtained from degradation of the chitosan and the DACs by NaNO 2 , the chitosan fragment was the most powerful elicitor for (+)-pisatin induc­tion. The NaNO 2 -degraded DAC 56% exhibited a com parable activity to the NaNO 2 -degrad-ed chitosan at low concentrations. The NaNO 2 -degraded fragments as well as the native poly­mer induced a relatively high amount of (+)-pisatin, while the acetone precipitate of chitosan oligomers from the HCl-catalyzed hydrolysate and their partially N-acetylated derivatives ex­hibited a moderate (+)-pisatin-inducing activity. These findings suggest the possibility that partially N-deacetylated chitin fragments could be one of the most promising elicitors in the pea system.

The effects of chloroacetamides on the acetylation of histone protein in maize (Zea mays) were studied in an in vitro assay. Neither alachlor nor metazachlor showed any influence on both of the investigated acetylating enzymes, the nuclear histone acetyltransferase A and the cytoplasmic histone acetyltransferase B. Furthermore, an effect of these herbicides on deacetylation of histones could be excluded.

14-Epicochlioquinone B (1) and 14-epidihydrocochlioquinone B (2) were isolated from sub­ merged cultures of Neobulgaria pura (Pers. ex Fr.) Petrak. 14-Epicochlioquinone B is a potent inhibitor of hum an and bovine platelet aggregation stimulated by different inducers. 14-Epidihydrocochlioquinone B does not inhibit the aggregation of platelets. In addition, both 1 and 2 exhibited cytotoxic and antimicrobial activites.

Dedicated to Prof. Aloysius Wild on the occasion of his 65th birthday Lepidium sativum, Cruciferin, Ribulosebisphosphate Carboxylase, Inhibition of Transcription Cress (Lepidium sativum) seeds were germinated in darkness. Seedlings were investigated for soluble proteins by SDS-PAGE. Two proteins were identified by microsequencing: the small subunit of ribulosebisphosphate carboxylase (SSU) and the alpha subunit of the storage protein cruciferin. Net synthesis of small and large subunits of ribulosebisphosphate carboxylase (SSU and LSU) was investigated by Western blot. Net synthesis of both subunits was inhibited by coumarin. To the contrary, net synthesis of cruciferin was increased by coumarin. With specific cDNA probes, we determined steady state levels of the corresponding mRNAs (rbcS mRNA for SSU, rbcL mRNA for LSU). Both mRNAs can be detected in dry seeds; their amount increases during germination in the dark. Incubation with coumarin inhibits this increase. Inhibition of development by coumarin on the level of transcription is discussed.

Thermal Denaturation, Trehalose, Yeast Pyrophosphatase, Water Activity, Carbohydrates Trehalose, a disaccharide of glucose, is accumulated in yeast cytosol when this organism is submitted to a stress condition. Recently it was shown that the level of trehalose increase up to 15 times when yeast cells are submitted to heat shock (De Virgilio et al., 1991). In this report we give evidence how trehalose may play an important role on the stress-survival of yeasts when submitted to a heat shock. We show that 1.5 M trehalose increases 13-fold the half-time for thermal inactivation (t 0.5 ) of yeast cytosolic pyrophosphatase at 50 °C. This thermal pro­tection conferred by trehalose is dose-dependent, after 10 min at 50 °C, a condition which inactivated pyrophosphatase, the presence of 2 M trehalose preserves 95% of total activity. Other carbohydrates were tested but were not so effective as trehalose. The presence of tre­halose at high concentrations in the reaction medium at 35 °C inhibits pyrophosphatase activity. This inhibition is less effective at 50 °C suggesting that under this condition the enzyme is temperature-protected and active.

Allophycocyanin (AP) was isolated from extracts of the cyanobacterium Mastigocladus laminosus. A fraction enriched in AP-associated polypeptides with apparent molecular masses of 21 -23 kD a in SDS-PAGE, was isolated on a preparative scale and identified as a homolo­gous mixture of C-terminal fragments of the core-membrane linker polypeptide L cm . The complex (α AP β AP ) 3 ·21 -23 kD a was reconstituted and characterized by sucrose density gradient ultracentrifugation, absorption, fluorescence emission and circular dichroism spectroscopy. The 21 -23 kD a polypeptides were found to induce spectral changes in AP similar to those induced by the small core linker polypeptide L c 8.9 . Possible functions of the complex in phycobilisomes are discussed.

The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHC II) was isolated from carnation (Dianthus caryophyllus L.) leaves by K + -induced aggregation of n-hep-tylthioglucoside-treated photosystem II particles. When solubilized with a mixture of lithium docedyl sulphate, octyl-β-D-glucopyranoside and dodecyl-β-D-maltoside the LHC II was re­ solved by mild sodium dodecyl sulphate-polyacrylamide gel electrophoresis into four oligo­meric forms and a monomeric one. LHC II contained five major polypeptides only two of which (27 and 26 kDa) were found to be its authentic components. The oligomeric forms of LHC II were found to differ in the stoichiometric ratios of the polypeptides present. The 26 kD a polypeptide was enriched in the largest oligomeric forms while the 27 kDa polypep­tide tended to form a monomer or to assemble as lower oligomeric states of LHC II.

Four varieties of P. vulgaris L. were tested for their symbiotic nitrogen fixation effectivity in combination with nine different strains of Rhizobium leguminosarum bv. phaseoli and Rhizobium tropici. Plants were grown under controlled conditions and harvested 23 days after planting. Acetylene reducing activity, total N-content and dry weight of individual plant components were determined. Significant differences due to plant x bacterium interaction were assessed by ANOVA, especially for the total nodule mass per plant and the acetylene reducing activity per nodule dry weight. Data for acetylene reducing activity per plant correlated highly with the corresponding data for the total N-content. The comparison of the total N-content in symbiotically grown plants, lacking supply of mineral N, with plants luxuriously supplied with mineral N (relative N-accumulation rate) revealed high values (between 60% and 70% of maximal N-uptake) for some symbiotically active plant/bacterium combinations for this early developmental stage of the symbiosis N 2 fixation potential for such symbioses.

The method of anomalous viscosity time dependencies (AVTD) was modified for the study of the changes in the chromatin conformational state (CCS) of rat thymocytes of the Wistar line. The response of the thymocytes of male rats to low-intensity millimeter waves (MMW) was examined. It was shown that MMW at power densities (PD) of 1 μW/cm 2 produced a resonance effect on the CCS in the frequency range of 41.56-41.67 GHz. The resonance fre­quency of the cell response did not vary significantly among five examined rats and was deter­ mined to be 41.61 ±0.01 GHz. A halfwidth of resonances was averaged to 40 MHz. The power dependence of the resonance effect was measured in the range of 10 -11 -10 -4 W/cm 2 . Statistically significant changes in CCS were registered, starting with 10 -9 /cm 2 . Right-and left-handed circularly polarized MMW were shown to differ in efficiency at the resonance fre­quency. The established regularities in the thymocyte response to low-intensity MMW was very similar to those which have been previously found for E. coli cells.

received October 23, 1993/March 1, 1994 Ethanol, Microsomes, Mitochondria, Lipid Peroxidation, Hepatotoxicity A group of male rats were intoxicated within 24 h by three successive i.p. doses of ethyl alcohol (7.5 g per 1 kg of the body weight). In parallel, a control group of rats were dosed i.p. with a physiological saline. At time intervals of 0 h, 4 h, 24 h, and 48 h after the intoxi­ cation, the content of thiobarbiturate-reactive substances (TBARS) as product of lipid per­ oxidation within the liver and brain microsomes and mitochondria was followed. In liver microsomes of the experimental rats there was a rapid increase (by 220%) in the content of TBARS during 4 h after the last application of ethanol, later on the level of lipid peroxidation decreased to the low original value. In other organelles examined only an insignificant increase in the content of TBARS was found. The results prove that an acute intoxication by ethanol does elicit an oxidative stress of the organism, expressed by a tran­siently increased production of TBARS. These oxidative and harmful changes for the cell structures are mostly located in the liver microsomes but a rapid repair of this damage fol­ lows. However, if such a short-term excessive abuse of alcohol is repeated more often, the above changes may lead to severe alcoholic injury

Coleoptera, Oryctes monoceros, African Rhinoceros Beetle, Aggregation Pheromone, Ethyl 4-M ethyloctanoate Ethyl 4-m ethyloctanoate is a male-produced aggregation pheromone of the African rhinoc­eros beetle, Oryctes monoceros (Olivier). It was identified by coupled gas chromatographic-electroantennographic detection (GC -EAD) and coupled GC-mass spectrometry (MS) of Porapak Q-trapped male-produced volatiles. Natural and synthetic ethyl 4-m ethyloctanoate elicited comparable antennal responses. In a field experiment (La Me Research Station, Côte d’Ivoire), synthetic ethyl 4-methyloctanoate released at 30 mg/day attracted both male and fem ale Oryctes, whereas the known, non-beetle-produced attractant, ethyl chrysanthemate, did not attract any Oryctes. Upon improvement of trap design and placement, and the identi­fication of synergistic (plant) volatiles, pheromone-based mass trapping may become an alternative and/or additional strategy to manage O. monoceros, one of the most destructive pests of commercial coconut, oil, and date palms in Africa.

In response to disturbance, the pycnogonid Pycnogonum litorale discharges a mixture of eight ecdysteroids (ES). Repeated intensive molestation causes 99% secretion of the endogenous ES present. The concentration of the total ES in the defensive effluent is 1.0 × 10 -3 mol · 1 -1 . 20-Hydroxyecdysone 22-acetate, the predominant ES, reaches 0.8 × 10 -3 mol · 1 -1 . This is sufficient to deter significantly feeding by the common shore crab Carcinus maenas, a generalist predator in the habitat of the pycnogonid. There is evidence that the secreted ES of P. litorale contribute to its unpalatability. The present paper describes for the first time defensive secretion in marine arthropods.

The intracellular arsenazo signal indicating the transient light-evoked change in cytosolic Ca 2+ (or Sr 2+ ) concentration was measured in Limulus ventral photoreceptor simultaneously with the receptor potential at 15 °C. The decline of the arsenazo signal has two phases (D1 and D2) when the photoreceptor is bathed in physiological saline. 1. When calcium is replaced by strontium in the superfusate both receptor potential and arsenazo signal are markedly increased in amplitude and the membrane potential is hyper­ polarized. The decline of the arsenazo signal is prolonged and becomes monophasic; the fast phase D1 of the decline disappears. 2. In strontium saline under voltage clamp conditions the slope of the monophasic decline of the arsenazo signal is the steeper the more negative the membrane voltage. 3. After replacing sodium by lithium in the superfusate the rise of the receptor potential and of the arsenazo signal are not much altered. The decline of the arsenazo signal, however, is slowed down more than 3-fold; this is due to the complete suppression of the fast phase D1 and the retardation of the slow phase D2 of the calcium re-decline. Interpretation: 1. The Na-C a exchanger can accept strontium as a calcium substitute. Strontium has a weaker desensitizing action than calcium. Strontium is not-or only very little -taken up by the endoplasmic cisternae. 2. In sodium-free lithium saline the Na-C a exchanger, the Na-K ATPase and the calcium uptake system of the endoplasmic cisternae do not function. Therefore the intracellular calcium level rises.

Leaves and young twigs of Hypericum balearicum L. exhibit lipophilic glandular products that can be re­ covered by rinsing green aerial parts with acetone. Major components of the resinous material are the triterpenes lupeone and lupeol. The intensely yellow col­ our of the acetone solution is due to a novel natural product, identified as 1,2,5-trihydroxyxanthone.

A series of methylated flavonols and two methyl flavones have been identified in the exudate of the American gumweed species Grindelia glutinosa and Grindelia robusta. They resemble the flavonoid patterns observed in other species of this genus, which thus shows a tendency for accumulation of methylated flavonols.