Volume 38, Issue 5-6

The X-ray Structure of Silybin from Silybum marianum Gaertn. was determined. The com­pound was found to be a diastereomeric mixture (1:1) in the benzodioxane part of the molecule explaining several tentative aspects about the structure known from NMR-measurements and HPLC-separations.

A procedure to identify dihydroflavonol (glucosides), cinnamic acids and anthocyanins in flowers of Petunia hybrida is presented. Nearly all known intermediates and anthocyanins ocur- ring in Petunia are separated on one column using different elution systems. Hydrolysis of extracts before HPLC and thin layer chromatography is in some cases necessary to make positive identification of flavonoids. Anthocyanins in flowers of Petunia hybrida can occur, depending on genotype, as acylated anthocyanins. Two types of acylated anthocyanins have been identified differing in polarity and thus in retention times on HPLC and TLC. The difference in acylation is genetically deter­mined and gives rise to minor colour differences.

Suspension cultures of Eschscholtzia californica accumulate the dihydro forms of the benzo- phenanthridine alkaloids sanguinarine, chelirubine, macarpine and chelerythrine, all of which are known to be constituents of the Eschscholtzia plant. Under most experimental conditions dihydrochelirubine was found to be the main constituent of the cultured cells. The specific yields of alkaloids varied from zero to 1.7% on a dry weight basis depending on the media conditions. The highest specific yield was 1.5 mg/g dry weight or 13 mg/1 with the growth medium B5. After transfer of the cells into the induction medium IM2 the alkaloid accumulation increased to 17 mg/g dry weight and 146 mg/1. The induction medium contained increased levels of sucrose, decreased levels of phosphate and was devoid of phytohormones. The effect of the various media conditions on the biosynthesis of phenolics was quite different to those found for the alkaloids.

The circulardichroism spectra (cd) of native and (partially) urea-denaturated C-phycocyanin (PC) in the spectral range 700-210 nm are presented. The large ellipticities observed in the chromophoric region of native PC are retained in the fully denatured state (8 ᴍ urea). This is similar to the behavior of the red form of phytochrome (P r ), but in contrast to C-phycoerythrin (PE). These differences are rationalized in terms of epimeric equilibria between P- and M-helix shaped chromophores. Depending on the number and location of the chirality centers present in the tetrapyrrol moities a priori, the excess populations of the inherently chiral P- and M-helices differ, thus accounting for large (PC, P r ) or small (PE) ellipticities in the denatured pigments. Hence, the large optical activity observed for the former is generated by an excess population of the P-helix induced by the asymmetric C-2, C-3 and C-3'. In PE the additional chirality center at C-16 counteracts the influence of the others. The excess population of the inherently chiral species is therefore lowered, in agreement with the nearly vanishing cd reported for denatured PE. The cd has also been studied at intermediate urea concentrations. Unfolding of PC with urea can be interpreted from these data as a stepwise process. Monitoring the urea induced unfolding of PC by cd at different wavelengths (λ = 220, 345, and 610 nm); the “melting point” of the apoprotein (4 -5 ᴍ urea) coincides with the extrema of the titration curves obtained in the chromophore region (345, 610 nm). These results give direct evidence for the existence of an intermediate species whose population reaches a maximum at 4-5 ᴍ urea.

Chromopeptides were prepared by pepsin digestion of C-phycocyanin isolated from the cyano­bacterium Spirulina maxima and of phytochrome isolated from seedlings of Avena sativa L. The chromopeptides were characterized by amino acid analysis. The ZZZ configurated chromophore of the phycocyanin peptide was transformed into its ZZE configurated isomer by the method of Falk et al. (Mh. Chemie 111, 159- 175, 1980) which had previously been applied to biliverdins. The 500 MHz 1 HNMR spectrum of the ZZE configurated chromopeptides confirmed that its chromophore has the 15 E configuration. Irradiation yielded the ZZZ configurated isomer for which the 1 H NMR spectrum was also recorded. Native phytochrome was irradiated at 660 nm to yield the maximum amount of the P fr from (about 75% of total phytochrome). By digestion in the dark the previously described P fr chromopeptide was obtained. The 500 MHz 1 H NMR spectrum was compared with that of the ZZE phycocyanin peptide. It confirmed the 15 E con­figuration of the P fr chromopeptide. Irradiation yielded the 15 Z configurated P r chromopeptide. Comparison of the high resolution 1 HNMR spectra of P fr and P r chromopeptides revealed that not only the chromophore resonances but also those of some amino acids are changed by the P fr → P r chromopeptide phototransformation. The results are discussed in terms of chromophore amino acid interaction.

Immature fruits and leaves of black cherry (Prunus serotina Ehrh.) accumulate the cyanogenic glucoside prunasin (the β-glucoside of (R)-mandelonitrile). Cell-free extracts from these tissues catalysed the stereospecific glucosylation of (R,S)-mandelonitrile to (β)-prunasin at rates of 0.2-2.0 μmol/h/mg protein. Uridine diphosphate glucose (K m = 0.32 mᴍ) acted as glucose donor. The optimum concentration of (R,S)-mandelonitrile was 20 mᴍ. Highest activity was exhibited at pH 7.0-8.0 in Tris-phosphate buffer, and no additional cofactors were required. β- Mercaptoethanol (14.5 mᴍ), provided in the homogenization medium to prevent browning of homogenates, did not stimulate the rate of prunasin production. In addition to (R)-mandelonitrile (100%), significant activity was shown towards mandelamide (21%), benzyl alcohol (15%), mandelic acid (8%) and benzoic acid (153%), but not towards prunasin. Mandelonitrile glucosyltransferase activity was most stable at - 20 °C in the presence of 10% glycerol.

The overall metabolism of [8- 14 C]adenine, [8- 14 C]adenosine, [8- 14 C]guanine, [8- 14 C]hypoxan- thine and [8- 14 C]inosine in suspension cultured cells of the lag, cell division, cell expansion and stationary phases and stem tissue of Catharanthus roseus was studied. On a fresh weight basis, absorption of all purine bases and nucleotides by the cultured cells was 10-400 times higher than that by the stem tissue. The conventional pathways of purine salvage and degradation were operative both in the cultured cells and stem tissue. [8- 14 C]Adenine and [8- 14 C]adenosine were extensively salvaged to nucleotides and nucleic acids in both the cultured cells and the stem tissue. [8- 14 C]-Guanine, [8- 14 C]hypoxanthine and [8- 14 C]inosine were incorporated into either salvage products (nucleotides and nucleic acids) or degradation products (CO 2 , allantoin and allantoic acid) of cultured cells and stem tissue. The highest incorporation rate expressed as a percentage of absorbed 14 C into the degradation products was observed in the lag phase (12h-old) cultured cells. Incorporation of all precursors into nucleotides and bases was much higher in the stem tissue than in the culltured cells.

Three l4 C-labelled 5-ring PAHs, benzo(a)pyrene, dibenz(a,h)anthracene and perylene were added to various cell suspension cultures of plants belonging to the Chenopodiaceae family. The differently configurated 5-ring systems varied in uptake and metabolism. The uptake of benzo(a)pyrene was highest in all cell cultures tested whereas the assimilation of dibenz(a,h)an­thracene and perylene was significantly less. The uptake of benzo(a)pyrene and dibenz(a,h)- anthracene was highest in those cultures which showed the highest increase in biomass. In contrast the uptake of perylene was highest in cultures whose increase in biomass was less. Previous investigations (H. Harms, W. Dehnen and W. Monch, Z. Naturforsch. 32 c, 321 -326 (1977)) showed that benzo(a)pyrene is metabolized to quinones and other oxygenated derivatives by Chenopodium rubrum cell cultures. It was demonstrated now that in further reactions these compounds are incorporated into insoluble fractions. With increasing time of incubation the amount of radioactivity in the extracted residue increased. The proportion of oxygenated derivatives formed seems to be correlated with the incorporation of radioactivity into insoluble fractions. Dibenz(a,h)anthracene turned out to be the most stable 5-ring system whereas perylene is metabolized to a certain extent but only small amounts of radioactivity could be detected in the extracted insoluble residue. The experiments showed that plant cell cultures maintain their specific behaviour over long periods. On the other hand each of the chemical compounds, because of its molecular size and configuration, is subject to its own specific metabolism in plant systems.

The ability of several geranyl derivatives to inhibit carotenoid synthesis in Synechococcus (Cyanobacteria) was measured using a cyanobacterial bioassay. The inhibitory activity of differ­ent molecules varied according to chain length and substituents. Pseudoionone, farnesyl acetate, geranyl acetate, geranial and farnesol proved to be the most active derivatives tested. 6-Methylhept-5-en-2-one, farnesyl acetone, linalool and geranyl linalool exhibited no effect when employed in concentrations as high as 100 ppm. Besides phytofluene, ζ-carotene was accumu­lated after application of sublethal amounts of active geranyl derivatives. Cell growth and chlorophyll a synthesis were only slightly affected under conditions were carotenoid synthesis was markedly inhibited.

The interconversion of carotenoids and quinones was investigated in beech and spinach leaves as well as isolated intact spinach chloroplasts following a dark-light transition. It is shown that isolated intact chloroplasts which are preincubated for 2 h at pH 7.6 in the dark and re­illuminated with strong white light are capable not only of deepoxidizing violaxanthin into antheraxanthin and zeaxanthin but simultaneously change the redox state of the plastoquinone- pool in their thylakoid membrane. At the same time as violaxanthin is deepoxidized plastohydroquinone-9 is oxidized to plastoquinone-9. If the light is turned off zeaxanthin is epoxidized into antheraxanthin and violaxanthin but no significant change in the redox state of the plastoquinone-pool occurred. It is concluded that the deepoxidation of violaxanthin is connected to the photosynthetic electron transport in that way that an acidification of the intrathylakoidal compartment by the vectorial release of protons from the water photooxidizing enzyme system and the plastoquinone- pool is required for the activation of the violaxanthin deepoxidase. This may be taken as further evidence that violaxanthin deepoxidase is located at the inner side of the thylakoid membrane. Additional evidence for this location site is given by the observation that neither deepoxidation of violaxanthin nor photooxidation of plastohydroquinone-9 occurred after onset of photosyn­thesis if non cyclic electron transport was inhibited by DCMU.

The G3P level in chloroplasts, rapidly isolated from spinach leaves during a light-dark cycle, oscillated between 2.5 and 4 nmol · mg -1 Chi, which corresponds to a concentration of nearly 0.1 -0.2 mᴍ. In order to study the role of the stromal G3P level on chloroplast lipid biosynthesis, G3P uptake, measured by silicone oil centrifugation, has been correlated with the lipid synthesizing capacity of intact spinach chloroplasts. The level of G3P in the chloroplast stroma was decreased by high orthophosphate (P i ) concentrations in the medium. This decrease was caused by a strong P i transport into the stroma, which is counterbalanced by a release of phosphorylated metabolites including G3P, mediated by the translocator. But because the reduced stromal G3P concentration exceeded about 3 times that for half saturation of the primary G3P acylation with oleoyl-ACP as preferred fatty acid donor, glycerolipid synthesis was not eliminated. Instead, the lowered G3P level in the stroma space limited the secondary acyla­tion step, indicated by the reduced incorporation of palmitic acid into the diglyceride fraction, and led to an accumulation of free oleic acid. Thus, beside its function as primary acyl acceptor, the stromal G3P level apparently controls the pool size of ACP bound palmitic acid by limitation of the chain elongation step from palmitoyl- to stearoyl-ACP in order to induce the specific palmitic acid channeling into the C-2-position of chloroplast lipids by the secondary G3P acylation. A similar function may be due to fatty acid consuming reactions from outside the chloroplast like acyl-CoA thioester formation in the outer envelope membrane, stimulated by exogenous CoA and ATP. In contradiction to earlier findings intact Percoll chloroplasts showed a measurable glycerolipid labelling (3-4%) from exogenous [ 14 C]oleoyl-CoA in the presence of G3P (0.5 mᴍ), although most of the radioactivity was found in the free fatty acid fraction (7-10%). Incorporation into diglycerides was increased two-fold under fatty acid synthesizing conditions in the medium and the resulting diglycerides were further galactosylated by UDP- galactose addition. The latter observations suggest, that even in spite of the envelope imperme­ability for physiological concentrations of long-chain acyl-CoA thioesters, fatty acid transfer from these substrates to typical chloroplast lipids cannot be totally excluded.

A number of industrial strains of Saccharomyces cerevisiae were converted to the petite form and tested for the ability to utilize galactose, maltose, sucrose, α-methyl glucoside and raffinose. The parent strains all metabolized these sugars aerobically. Twelve of the petite forms did not utilize galactose, six failed to utilize maltose, 17 did not utilize x-methyl glucoside, and 18 did not utilize raffinose. The petites of two distiller’s yeast strains did not utilize sucrose. The respiratory-competent parent strains nearly all fermented galactose, maltose, sucrose and raffinose, though 19 strains did not ferment α-methyl glucoside microaerophilically. Three strains did not ferment galactose, two fermented it only after several days adaptation, one did not ferment raffinose, and two did not ferment sucrose under microaerophilic conditions. Six respiratory-competent strains which did not utilize galactose when in the petite form fermented higher (10%) concentrations of glucose and maltose under microaerophilic conditions, but only three of these fermented galactose. The implications of these findings for the use of such strains in industry are discussed briefly.

In vivo and in vitro experiments were performed in order to study the regulatory role of trans- cinnamic acid and its hydroxylated derivatives (p-coumaric acid, caffeic acid) on the deamina­tion of phenylalanine catalyzed by PAL (EC 4.3.1.5). Trans-cinnamic acid inhibits growth and reduces the content of soluble proteins of anthocyanin-containing carrot cells grown in suspen­sion. There is strong evidence from the polysomal patterns and from the effect of trans-cinnamic acid on protein synthesis in vitro that protein synthesis is inhibited. The kinetic data of PAL clearly demonstrate that trans-cinnamic acid inhibits the enzyme by a noncompetitive mecha­nism. On the contrary, ʟ-α-aminooxy-β-phenylpropionic acid (ʟ-AOPP), a competitive inhibitor of PAL, does not affect protein metabolism.

Two O-methyltransferases specific for flavonol rings A and B were isolated from young flower buds of Lotus corniculatus. They were partially purified by ammonium sulphate precipitation and successive chromatography on Sephadex G-100 and Polybuffer ion exchanger. One enzyme focused at pI 5.5 and catalysed the O-methylation of position 8 of flavonols with a pH optimum of 8.1. The other enzyme had a pi of 5.1 and preferentially attacked position 3' at an optimum pH of 7.7. The methylated products of both enzymes seem to contribute to the flower colour of Lotus and may be used as biochemical markers in genetic studies of this genus.

Catalysis and regulation of CO 2 fixation differ in a characteristic manner in their response to anionic modifiers and the polarity of the reaction medium. Monovalent inorganic anions inhibit catalysis and CO 2 -activation of the ᴅ-ribulose 1,5-bisphosphate carboxylase/oxygenase from spinach, whereas the activity and binding of NADPH and effector sugar phosphates are affected only at appreciably higher concentrations. In contrast such modulators with a dianion structure stimulate CO 2 fixation by an increase of the affinity of the enzyme for the activator CO 2 and stabilization of the reactive carbamate. Structure-activity studies revealed a broad specificity of the enzyme for these regulatory effects. Essentially amino groups are involved in these processes. Certain organic solvents, as methanol or acetone, stimulate CO 2 fixation by a similar modification of the CO 2 activation centers, as induced by dianionic effectors. These results infer that such effects are due to a decrease of the polarity at the regulatory centers of the enzyme and a concomitant change of the pK of the active lysine responsible for the binding of the activator CO 2 . A correlation of effector binding and activity demonstrates that already low, non-saturating concentrations of such modifiers induce high activation levels of the carboxylase and prevent the dissociation of the activated ternary complex. It is discussed that the central problem concerning the catalytical competence of ᴅ-ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the presence of active site directed dianionic effectors can be solved kinetically.

A cysteine desulfhydrase was purified 110-fold from the green alga Chlorella using conven­tional techniques. The isolated cysteine desulfhydrase was specific for ᴅ-cysteine having no activity towards ʟ-cysteine. ᴅ- and ʟ-cysteine desulfhydrase activities can be separated using DEAE-cellulose chromatography techniques. The isoelectric point of this enzyme was deter­mined to be around a pH of 4.5 using a chromatofocussing column. The pH-optimum for the ᴅ-cysteine desulfhydrase was found to be in the range of 8.5 to 9 and the apparent K ᴍ for ᴅ-cysteine was determined to 0.16 mᴍ. The enzyme was active without addition of metal ions and EDTA or citric acid did not inhibit this activity.

Regulation of nitrogenase activity in Rhodopseudomonas capsulata AD 2 differs in several respects from other Rhodospirillaceae: 1)Nitrogenase activity in this strain grown under severe N-starvation was fully derepressed, but in contrast to other Rhodospirillaceae, it was inhibited by ammonia in vivo. 2)Nitrogenase in extracts of glutamate grown cells was fully active and not further stimulated by Mn 2+ . 3)Treatment of N-starved or glutamate grown cells with ammonia before harvest did not cause inactivation of nitrogenase in vitro.

Nitrate reductase from mutant 305 of Chlamydomonas reinhardii has been purified about 90-fold and biochemically characterized. The enzyme can use reduced flavins and viologens as electron donors to reduce nitrate but, unlike the nitrate reductase complex from its parental wild strain, lacks NAD(P)H-nitrate reductase and NAD(P)H-cytochrome c reductase activities, does not bind to Blue-Agarose or Blue-Sepharose and exhibits a significantly lower molecular weight (177.000 vs. 241.000), whereas its kinetic characteristics and its sensitivity against several inhibitors and treatments are very similar to those of the terminal nitrate reductase activity of the wild strain complex. Spectral studies and antagonistic experiments with tungstate show the presence of cytochrome b 557 and molybdenum. These facts lead us to propose that nitrate reductase from mutant 305 has a protein deletion which affects the pyridine nucleotide binding region of the diaphorase protein but without any effect on the terminal nitrate reductase activity.

Membrane fractions of the cyanobacterium Synechococcus 6301 obtained by french press treatment following sonication catalyzed an oxygen-dependent oxydation of cysteine to cystine. For 1 O 2 consumed four cysteine were oxydized. Oxygen uptake was completely inhibited by 1 mᴍ KCN. Only ᴅ- and ʟ-cysteine were active and partial activity was observed with ᴅʟ-homocysteine and cysteamine. No activity was found with glutathione, mercaptoethanol, thioglycerol, dithioerythritol, or N-acetyl-ʟ-cysteine. Cysteines with a blocked acid group such as O-methyl-ʟ-cysteine and O-ethyl -ʟ-cysteine were oxydized rapidly by Synechococcus membrane fractions. Rates of about 200 μmol of cysteine oxydized per mg chlorophyll and hour were measured. This cysteine respiration is discussed in relation to dark inactivation of enzymes.

A specific and sensitive radioimmunoassay for human choriogonadotropin (hCG) has been developed using rabbit antiserum to chemical analogs of beta subunit of human chorionic gonadotropin prepared by controlled reduction and S-alkylation of its disulfide linkages. The assay was highly specific for hCG as the binding of [ 125 1]-hCG to the antibody was not affected by standard human lutropin, by human male serum, postpartum serum from women, serum from post-menopausal women and human menopausal gonadotropin (Pergonal). The assay was highly sensitive, the minimal detection limit in terms of highly purified hCG (L-129, 12500 IU/mg) being 1 ng/ml or 0.2ng/tube (or 12mlU/ml in terms of WHO 2nd international reference preparation of hCG). Using this assay we were unable to detect any immunoreactive hCG in human tissues like lung, liver and colon. The high specificity, sensitivity, accuracy and repro­ducibility of the assay make this a highly desirable radioimmunoassay for human chorio­gonadotropin.

Changes in the absorption spectra of P. cruentum and phycobiliprotein are observed as a function of hydrostatic pressure. With phycobiliprotein both in solution and in algae, increasing hydrostatic pressure results in bathochromic shifts of the absorption maxima. In addition, there is a splitting of the absorption band of phycoerythrin. When P. cruentum is subjected to 250 bars there are increases in absorption by chlorophyll (at 700 and 698 nm), phycocyanin (at 640 nm) and phycoerythrin (at 580 and 550 nm). When a cell free solution of phycobiliprotein is subjected to 300 bars there are increases in absorption by phycoerythrin (at 570 and 550 nm) and phycocyanin (at 634 nm).

Male mice were i.p. injected with two doses (5&15 mg/kg body weight) of [1- 14 C]ethyl-labelled chlorpyrifos. The radioactivity in liver, fat, kidney and urine was measured 6, 24, 48, and 192 h after treatment. Liver RNA and DNA were isolated and hydrolyzed and the bases separated by ion-exchange chromatography. Radioactivity resulting from incorporation and alkylation of RNA and DNA was measured. Labelled 7-ethylguanine was found in RNA hydrolysate which amounted 5.5 × 10 -3 calculated as fraction of the applied dose. In DNA hydrolysate [ 14 C]7-ethylguanine was missing and the major radioactivity was found in two unknown peaks, one of which corresponds to 3 × 10 -2 of the applied dose. The results indicate that the extent of alkylation obtained with clorpyrifos is high as compared with other organophosphates with methyl esters.

Electromagnetically induced currents pulsating at very low frequency stimulated calcium uptake by chick embryo tibia rudiments only when bicarbonate was present in the culture medium. A bicarbonate-dependent Ca 2+ -ATPase might be implicated in coupling of the electromagnetic signal with processes that promote Ca-transport and storage in bone tissue.

Addition of either ATP or ouabain to the culture medium markedly depressed thymidine incorporation into DNA in Raji cells. The electromagnetic field, pulsating at very low frequency, did not affect DNA synthesis in normal culture media nor did it alter its ouabain-inhibition, but it partially reversed the ATP-inhibition. In spite of the presence of ATP, ouabain prevented stimulation of ATPase and DNA synthesis by the field. Although no mechanism is known for the action of either ATP or the field, the results may be interpreted in light of existing speculations. In the absence of the field, external ATP may go into an ATP pool that either blocks ATPase or feeds adenyl cyclase, which hinders DNA synthesis. In contrast, the electromagnetic field may either turn off adenyl cyclase or simply stimulate the ATP-depressed ATPase.

1.Lowering the extracellular calcium concentration from 10 mmol/l to 1 nmol/l causes, besides reducing membrane potential (PMP) and peak amplitude (h max ) of the light response of the Limulus ventral nerve photoreceptor (see Stieve and Bruns [1]), a prolongation of the time course of the light response. The retarded time course (characterized by latent-period t lat , time-to-peak t max , decrease time t 2 and decline quotient Q HN ) caused by low calcium concentration is not antagonized by either reducing the sodium concentration (from 0.5 to 0.05 mol/l) or increasing the magnesium concentration (from 5× 10 -5 to 5 × 10 -2 mol/l) in contrast to the effects on the PMP and h max . 2. This effect of lowering the calcium concentration on the time course of the ReP is distinctly different from that on membrane potential and transient of the ReP described before. It is not characterized by a calcium/sodium binding competition but is probably more closely related to the bump-generating mechanism. It can be explained on the assumption that the time parameters of the ReP are primarily determined by the latency distribution of the underlying bumps which is expanded under low calcium conditions.

A crown-gall suspension of Matricaria chamomilla L. was cultivated in the presence of an adsorbent (activated charcoal, AC). The culture produces besides other secondary products coniferyl aldehyde which is excreted by the cells and distributed between cells, medium, and the AC according to equilibrium distributions with more than 95% of the substance adsorbed to the AC. This deprivation of coniferyl aldehyde from the medium enables the cells to increase the production of this substance up to 60-fold. The system Matricaria/coniferyl aldehyde serves as a model for the improvement of the production of secondary products by means of plant cell suspensions.

The main triterpenol, isolated from the alcohol fraction of very old green leaves of Hoya australis R. Br. ex Traill, has been identified as 3,4-seco-3-nor-olean-12-en-1-ol by mass spectral and NMR data.

A survey was made of the distribution of sterols in five Dioscorea species tubers. All contained /7-sitosterol, stigmasterol, cholesterol and campesterol, whereas cycloartenol was detected only in two Dioscorea species.

A new flavonolglycoside, quercetin-3-α-ʟ-(2-O-α-ʟ- rhamnopyranosidoarabo-pyranoside, has been isolated from seeds of Brassica nigra. Its structure is prooven by 13 C-NMR.

Mycelial cultures of the ascomycete Verpa digitaliformis produce a yellow pigment, verpacrocin. Its structure was determined by spectroscopic methods to be 2,4,6,8,10,12,14- hexadecaheptaenedial (3).

High performance liquid chromatography was used to quantify the sesquiterpene phenolic esters, Guayulin A and -B in Parthenium argentatum (guayule) and F 1 hybrids of guayule with Parthenium schottii, P. fruticosum var. trilobatum and P. tomentosum var. stramonium. The distri­bution of these phenolic acid esters in all parts of the plants are reported and their inheritance in hybrids is discussed.

The chemical composition of the secretion from the anal sacs of a female of Civettictis civetta is analysed using gas- liquid chromatographical and mass spectrometrical tech­niques. The secretion mainly consists of cholesterol esters, monoester waxes, cholesterol, and free fatty acids of chain lengths not under C 12 ; highly volatile components were not traceable. The functional significance of the anal sac secretion is discussed. `

Seryl tRNA (anticodon GCU) from mammalian mito­chondria shows in comparison to other mitochondrial tRNAs additional special features differing from the generalized tRNA model. When arranged in the tradi­tional cloverleaf form, eight bases fall within the TΨC loop, and the entire dihydrouridine loop is lacking. This seryl tRNA molecule is therefore shorter than other tRNAs. It was originally thought to represent a mito­chondrial analogon of 5 S rRNA and its precise classifica­tion is still disputed. The present studies suggest that this mitochondrial tRNA represents a fossil molecule which is related to the common ancestor of the present tRNA and 5 S rRNA molecules.

Whereas human red blood cells and protoplasts of leaves of Avena sativa show rotation only at discrete frequencies in the kHz-range of a linear alternating electric field, rota­tion of these cells is observed at practically every fre­quency in the MHz range (15 to 200 MHz). The cell rotation in the MHz-range can be explained in terms of field induced polarisation and orientation of per­manent dipoles within the membrane and the cell. This interpretation is supported by the finding that Chelex beads (polystyrene cross-linked with divinylben- zene and coupled to iminodiacetic acid) do exhibit rota­tion in the MHz-range, but not in the kHz-range. It is most interesting that the Cu 2+ - and Ca 2+ -forms of the Chelex beads show a shift in the rotation frequency spectrum in addition to an increase in the magnitude of the rotation speed with respect to the Na + -form. At frequencies in the MHz-range at which rotation of the Chelex beads is not observed, formation of chains of beads from the electrodes occurs instead. This is due to positive polarisation of the beads leading to positive dielectrophoresis. The results support the view that rotation needs negative polarisability which is determined by the functional groups.

The interior of wood ant nests (Hymenoptera, Formicidae, Formica polyctena Förster) and artificial piles of nest material has been heated with heating wires in the field. In the artificial piles a heating power of 1 - 5 Watt is suffi­cient to cause a temperature increase equivalent to that caused by ants in their nests without additional heating. Whereas in artificial piles temperatures increase with in­creasing heating power, the ants prevent temperatures to exceed 34.6 degrees C in their natural nests, even if these are heated with a power of more than 20 Watt.