Band 37, Heft 10

Slices from ripe strawberry fruit (in shape of segments) metabolize exogenous ʟ-alanine, acetate, pyruvate, n-butyrate, 2-ketovalerianate, n-butanal, n-hexanoate or d,l-mevalonic acid-δ-lactone to yield fruit-typical aroma compounds and some of them to considerable extent. Employing standard-controlled aroma separation by liquid-liquid-extraction, as well as prefrac­tionation on silica gel, the aroma components were determined by GC and GC-MS. Alkyldonors were converted more quickly and selectively than acyldonors, the former resulting in twenty-to thirtyfold increase in some of the concentrations of fruit-esters under specific conditions. The increase in ester biosynthesis ʟ-alanine is directly proportional to the concen­ tration of substrate up to 3 mmol/1. After addition of the above mentioned precursors the con­ centration of (+)-nerolidol, a terpenoid compound o f strawberry aroma, is increased.

Cell suspension cultures of Stemmadenia tomentosa synthesized under normal growth condition the eight major indole alkaloids: (-)-tabersonine, (-)-minovincinine, (+)-conoflorine (voaphyl-line), condylocarpine, (+)-tubotaiwine (dihydrocondylocarpine), (-)-norfluorocurarine (vin-canine), (-)-vinervine, and (-)-coronaridine. These alkaloids consist of the three different types, Aspidosperma, Strychnos and Iboga. In contrast, cultures o f Voacanga africana produced mainly one alkaloid group (Aspidosperma-type) represented by (-)-tabersonine, lochnericine and (-)-minovincinine. Therefore this cell culture seems to be qualified for investigation concerning the biosynthesis of Aspidosperma alkaloids.

After a lag-phase of 1 h a mycelial Suspension of Fusarium javanicum completely degraded 5,7-dihydroxy-4'-methoxyisoflavone (biochanin A) to a series of transiently accumulating catabolites. The compounds were elucidated by spectroscopic techniques and are arranged in the first known degradative pathway for an isoflavone: biochanin A → dihydrobiochanin A → 3-(p-methoxyphenyl)-4,6-diketo-5,6-dihydro-4H-pyran → p-methoxyphenylacetic acid → p-hy- droxyphenylacetic acid → 3,4-dihydroxyphenylacetic acid → CO 2 . The carbon atoms of bio­chanin A not accounted for by this sequence are discussed in relation to microbial flavonoid pathways.

The cyanobacterium Synechococcus 6301 is able to use a limited number of sulfur compounds as the only source of sulfur supply such as sulfate, thiosulfate, thioacetic acid, mercaptoacetic acid, thioacetamide, ʟ-cysteine and glutathione. Compounds containg thioether linkages such as methionin or S-methylcysteine and all compounds investigated so far containing sulfonic acid structures do not support growth. Growth inhibiton was observed by addition of aminomethane- sulfonic acid or cysteamine. When non-growth sustaining sulfur compounds are added as sulfur source, the C-phycocyanin content of the Synechococcus cultures decreased drastically, causing a shift in color from blue- green to yellow-green. An analysis reveals the degradation of C-phycocyanin whereas chlorophyll formation still proceeds to a certain degree in growing sulfur-starved cells. Supplementation of a suitable sulfur source induces a period of intense and preferential C-phycocyanin synthesis prior to resumption of normal growth.

Cells of the archaebacterium Methanosarcina barkeri were grown strictly anaerobic in defined media. 57 Fe-Mössbauer Spectroscopy of methanol grown cells oxidized in the presence of air demonstrated only the state of Fe 3+ whereas active cells under reducing conditions offered spectra of two additional iron sites in the Fe 2+ state. Furthermore the 57 Fe hyperfine interaction data at different temperatures gave evidence that cells cultivated with methanol or acetate as substrate contained ferredoxin like compounds.

The lifetime of fluorescence from pea chloroplasts at room temperature increases with age. The ratio of the fluorescence intensities of the slow to fast decay components, decreases with age o f the chloroplasts. This observation can account for the wide range of lifetimes reported in the literature. The variability of biological material (cultured and prepared with similar procedures) introduces considerable variation in the fluorescence lifetimes measured with pea chloroplasts. Sonication of chloroplasts results in an increase in both the fast and slow fluorescence lifetimes.

Formation of H 2 O 2 in the course of peroxidase catalyzed IAA metabolism was measured using the peroxide-dependent decarboxylation of [ 14 C]glyoxylate and the oxidation of phenolic substrates giving rise to fluorescent products in IAA/HRP systems. The results agree with the recent concept of IAA metabolism which includes the formation of H 2 O 2 in the course of oxidase action on IAA and the consumption of this H 2 O 2 by subsequent peroxidase action in the presence of phenolic cosubstrates.

The inhibition of photosynthetic CO 2 -assimilation and of the variable chlorophyll fluorescence as well as uptake and transport of 14 C-labelled bentazon and the possibilities for a herbicideinduced shade-type modification of the photosynthetic apparatus were investigated in bentazonsensitive weeds (Galium, Sinapis, Raphanus) and in the tolerant crop plants wheat and maize. 1. In weeds the depression of photosynthetic CO 2 -assimilation is irreversible, whereas tolerant plants recover due to the metabolization of the active herbicide. 2. A lower rate of uptake and transport of bentazon associated with its fast metabolization is the reason for the tolerance of crop plants towards bentazon. 3. The transport of [ 14 C]bentazon proceeds in the tracheary elements of the xylem. Uptake and transport of bentazon in the weeds are light dependent. 4. The loss of variable fluorescence (Kautsky effect) in the leaves after root application o f bentazon proceeds much faster at high-light than at low light conditions and confirms the light-dependency of the bentazon transport. 5. In the sensitive dicot weeds bentazon not only inhibits photosynthetic electron flow and depresses CO 2 -fixation but also induces the formation of shade-type chloroplasts which are less efficient in photosynthetic quantum conversion. This bentazon-induced modification of the photosynthetic apparatus (e.g. changes in ultrastructure, pigment ratios, and levels of chloro-phyll-proteins) contributes to the effectiveness of bentazon as a herbicide.

Bleaching of chlorophyll was studied in the leaves of rye seedlings (Secale cereale L.) treated with four chlorosis-inducing herbicides of different potency (weak photodestructions, group 1: aminotriazole, haloxidine; strong photodestructions, group 2: San 6706, difunone). Chlorophyll deficiency and particularly the inactivation of a chloroplast marker enzyme, NADP-dependent glyceraldehyde-3-P dehydrogenase, that occurred in the presence of group 2 herbicides were stronger in red, than in blue, light. When grown in white light of low intensity (10 lx) herbicide-treated leaves contained chloro­ phyll, 70 S ribosomes and unimpaired activities of NADP-dependent glyceraldehyde-3-P de hydrogenase. At 10 lx only the leaves treated with SAN 6706 and difunone were strongly carotenoid-deficient but not those treated with group 1 herbicides. After all herbicide treatments 10 lx-grown leaf tissue was, however, not capable of photosynthetic O 2 -evolution indicating some disorder of photosynthetic electron transport. Leaf segments grown at 10 lx were exposed to a high light intensity of 30000 lx at either 0 ° C or 30 °C. In treatments with group 1 herbicides chlorophyll accumulation was stopped in bright light at 30 °C but breakdown was not apparent. Only at 0 °C and in the presence of high, growth-reducing, herbicide concentrations chlorophyll was slightly degraded. The RNAs o f the 70S ribosomes were, however, clearly destroyed at 30000 lx and 30 °C in aminotriazole-treated leaves. In leaves treated with group 2 herbicides chlorophyll was rapidly degraded at 30000 lx both at 0 ° C and 30 °C, however, only in the presence of O 2 , indicating a true photooxidative and mainly photochemical nature o f the reactions involved. This chlorophyll breakdown was accompanied by the photodestruction of 70S ribosomes and the inactivation of NADP-glyceraldehyde-3-P dehydrogenase.In treatments with group 1 herbicides photoinactivation of the latter enzyme did not occur, although it was clearly localized in the bleached plastids, as demonstrated by gradient separation of organelles. In the presence of group 2 herbicides the chlorosis was originating from a direct photo­ oxidation of chlorophyll, accompanied by a massive destruction of other plastid constituents and functions. In treatments with group 1 herbicides photodestructions appeared to be much weaker and insufficient to affect chlorophyll directly. Mediated through some photodestructive inter­ ference with obviously more sensitive plastid components, such as their ribosomes, further chlorophyll accumulation was, however, prevented.

Rotation of single cells (mesophyll protoplasts of Avena sativa) induced by a planar, homogeneous rotating field has been observed at a frequency of 20-40 kHz (conductivity of the external mannitol solution 6x 10 -5 Ω -1 cm -1 ). This variation in optimum frequency is largely due to an inverse dependence on cell radius. Rotation direction is opposite to that of the field, and can be reversed at will by reversing the field. The maximum speed of cell spinning was a few cycles per second (and thus always much slower than that of the field) and was proportional to the square of the amplitude of the field. The rotation of a single cell in a rotating field is expected on the basis of the dipole-dipole theory developed by Holzapfel et al., (J. Membrane Biol. 67, 1-14 (1982)), for multi-cell rotation. Measurements of the dependence of optimum applied field frequency on medium conductivity indicate that the dipole is generated by interfacial (Maxwell-Wagner) polarization. The required frequency is a linear function of the conductivity of the external solution. This relationship is used to derive a value for the specific membrane capacitance. Further applications of this technique for cell and membrane research are discussed.

Saccharomyces cerevisiae nuclear membranes were prepared from isolated nuclei by digesting chromatin with deoxyribonuclease after an initial treatment of nuclei with very diluted buffers. When the nuclear membranes were treated with 5% Triton X-100 and 1 ᴍ NaCl an insoluble fibrous net was obtained which consisted mainly of protein with Mr values of 85000, 48000, 45000, 39000 and 31000. Lamins, a set of proteins with M r = 65000-75000, which were shown to be the major proteins of the insoluble nuclear membrane residue of higher eukaryotes, were not found.

Free living cells of Rhizobium japonicum 61-A-101 and bacteroids from Glycine max var. Mandarin infected with the same strain utilized malonate with a substrate saturation greater than 10 -2 mol/l. At low concentrations of malonate (10 -5 mol/1) the free living cells were significantly more active in utilizing malonate than bacteroids. In bacteroids two substrate saturation ranges were found, one between 3 x 10 -4 mol/l and 10 -3 mol/l, the other at more than 10 -2 mol/l. Utilization of malonate was not affected by 10 to 100 times larger concentrations of either arabinose or xylose. 10 -3 mol/l succinate inhibited the utilization of malonate (10 -4 mol/l) completely in bacteroids, and by 90% in free living cells. Succinate utilization (10 -4 mol/1) was reduced in those cells exposed to 100 times higher malonate concentration only by 20-30% . Utilization and incorporation of pyruvate and 2-oxoglutarate into bacteroids was also only slightly affected by 100 times larger malonate concentration. Citrate utilization by bacteroids however was reduced by more than 70%. The rate of endoxidation of malonate as sole carbon source ( 14 CO 2 production from [2- 14 C] malonic acid)was about 1.5 μmol · h -1 • mg protein -1 and about half the rate with Pseudomonas putida and 70% o f the rate with Pseudomonas fluorescens under the same conditions (pH 6.0, 28 °C).

Alanine dehydrogenase (E.C. 1.4.1.1.) from nitrogenase repressed free living cells of Rhizobium japonicum 61-A-101 was purified 370 fold to a specific activity o f 30.4 (μmol pyruvate · min -1 · mg protein -1 . The same enzyme from effective bacteroids from nodules of Glycine max var. Mandarin, infected with the same strain was purified 150 fold to a specific activity of 35 units. The enzyme from both preparations was identical in the molecular weight of about 168 kD with four identical subunits of 42 kD. The alanine dehydrogenase is, therefore, different from the same enzyme from Bacillus subtilis (molecular weight 228 kD) and from Anabaena cylindrica (molec­ ular weight 270 kD). The K ᴍ data for the enzyme from Rhizobium japonicum are: 4.7 mmol/l for NH + 4 0.68 mmol/l for pyruvate and 44 μmol/l for NADH. Specific activity of the enzyme in total cell extracts from eight other strains of Rhizobium japonicum (3 effective strains, 5 ineffective strains) was only 20 to 30% o f the activity with strain 61-A-101. No correlation between alanine dehydrogenase activity and nitrogenase activity in these other eight strains was observed. The function of alanine dehydrogenase in Rhizobium japonicum in ammonium assimilation and cell wall differentiation is discussed.

Semi-empirical studies by the MNDO and MINDO-3 methods together with ab initio studies by the Hartree Fock method, have been performed on the tautomers of cytosine (C) and hydroxycytosine (HC), in each case with full optimisation of the molecular skeleton. The results are in agreement with recent solution studies of these systems, and show that the amino form of C and the oxime form of HC are the lowest energy tautomers. Thus the property is one of the ring system rather than environment. Various conformers of the imino tautomer of 5-methyl-N(4)-hydroxycytosine were studied by MINDO/3 and PCILO calculations; although only partial geometry optimisation was performed, it seems unlikely that the molecule can be a complementary base to adenine in the Watson-Crick sense.`

The biological efficacy of vitamin C depends on its redox abilities as given by the relations between ascorbic acid, semidehydroascorbic acid, and dehydroascorbic acid. It is shown by means of proton magnetic resonance spectroscopy that the enzymatic (by ascorbate oxidase) as well as non-enzymatic (by iodine) oxidation of ascorbic acid is, in principle, reversible despite the hydration and structural changes during the formation of dehydroascorbic acid. The strong redox activity of semidehydroascorbic acid which results in a fast disproportionation to ascorbic acid and dehydroascorbic acid is inferred from an inversion of the electrochemical potentials of the vitamin C redox system. The capacity of this is maintained by a fast reduction of dehydro­ ascorbic acid e.g. by reduced glutathione, preventing its delactonization and further degradation.

A method is described for the continuous biological monitoring of the effluent from a high resolution gas chromatographic column using a single cell recording technique. The system can be used to provide precise information on the retention times of compounds with olfactory activity that are not detected with a coupled gas chromatograph - electroantennogram system.

Electroantennogram studies on C. laricella males demonstrated that the title compound, (Z)-5-decen-l-ol (Z5-10:OH), elicited the highest response among a series of straight-chain, C 10 to C 16 alcohols, acetates and aldehydes tested. From selective adaptation of antennal responses it was concluded that an additional type of receptor cell responded to the corresponding acetate, Z5-10: Ac. Field attraction experiments were carried out by using delta-type sticky traps and rubber-cap odour dispensers. The main test sites were located in the Swiss Alps, Black Forest and northwestern Germany, and included both European and Japanese larch stands, having different degrees of C. laricella infestations. At all test sites pure Z5-10:OH proved to be highly attractive to native male moths over a range of different lure doses, with a progressive increase of captures towards the higher (100 μg, 1000 μg) attractant sources. However, following captures of 200-400 moths/trap the “retaining capacity” of the sticky surfaces of the traps were found to decline markedly; in tests of the higher attractant doses at sites of higher moth densities, this “saturation effect” frequently occurred within a few hrs of trap exposure, thus demonstrating the limitation in the use of sticky traps for monitoring economically-relevant C. laricella populations. Trap placement studies (using the standard attractant of 100 μg Z5-10:OH) showed substantial captures only for those traps placed on green branches within the host crowns. The acetate analogue (Z5-10:Ac) strongly reduced male responses to the attractant alcohol (Z5-10:OH) when evaporated from the same trap, admixtures of 0.3% and 1% of this acetate reducing captures by 90% and almost 100% respectively. Possible functions of this inhibitor are briefly considered. No evidence for attractant synergism was obtained during the present study. The results suggest that Z 5-10: OH is a major constituent of the yet unidentified C. laricella sex pheromone.

Endogenous ecdysteroids as well as radiolabelled exogenous ecdysone were crosslinked to a protein when haemolymph from blowfly larvae was irradiated with UV-light under optimized conditions. This indicates that larval haemolymph of blowflies contains an ecdysteroid-binding protein. The crosslinked ecdysteroid-protein complex was shown to form a ternary complex when mixed with ecdysteroid-specific antibodies. Formation of the ternary complex was due to a specific interaction of the binding sites of the antibodies with the steroid. This specific interaction was used to isolate the ecdysteroid-protein complex from irradiated crude larval haemolymph by immunoadsorption. The method described here represents a rapid approach for the isolation of steroid-binding proteins by a combination of photoaffinity labelling and immunoadsorption.

To elucidate the structure-activity correlations we have performed an X-ray structure analysis of the title compound (1), which is a muscarinic agonist of the natural neurotransmitter acetyl­ choline. 1 crystallizes in the monoclinic space group P 2 1 /n with 2 molecules per asymmetric unit. Lattice parameters are: a = 10.375(6), b = 12.468(5), c = 15.274(17) Å; β= 95.32(7)°. The structure was solved by direct methods and refined to an R-value of 0.14 for 1828 observed reflections. Both cations in the asymmetric unit are disordered. In the crystal structure at least four conformations of the cation occur, indicating a pronounced conformational flexibility of the neurotransmitter cation. The anions are arranged stereospecifically with respect to the quaternary trimethylammonio methyl group. The geometry of triangles which are defined by a nitrogen of the quaternary ammonium group and an ether oxygen on one hand and an anion occupying a specific type of tetrahedral faces of a (CH 3 ) 3 N + -CH 2 group on the other hand, is characteristic for muscarinic agonists if they contain an ether or ester oxygen in the analogous position to the ester oxygen of acetylcholine.

Lysine rich histone and polylysine are bacteriolytic for Bacillus subtilis and Escherichia coli cells, whereas histones H2A, H2B and H3, assayed separately are not. Polyarginine bacteriolysis of E. coli with polycation 10 μg/ml decreased with higher concentrations, the killed nonlysed cells exhibiting wall alterations. All bacteriolytic polycations were lytically effective under reciprocal shaking, but not under magnetic stirring conditions, demonstrating the requirement for cell lysis of mechanical fields developed in oscillatory movements. Scanning electron microscopy of histone H1 treated B. subtilis cells showed the formation of globular bodies (polionosomes) in the cell surface. The interference of Ca 2+ and 0 °C exposure with the polycation action observed especially in E. coli, the polionosomes, and the dynamics in polycationic cell lysis, considered together, suggest the existence o f wall supramolecular subunits (murameres), defined by their ability to form polionosomes. The murameres undergoing reversible conformational transitions induced by ectobiological signals, e.g., Ca 2+ , would make up an uptake system. The involvement of this system in environmental interactions and DNA uptaking, as well as the general stereo-enzyme like nature o f the conformational changes caused by polycations are discussed.

Attention has recently focussed on the heavy metal thallium as an environmental contaminant of increasing importance. From accidental or suicidal ingestions of thallium it has been known for many years that cardiovascular disorders regularly emerge, and for this reason, a variety of investigations of cardiological interest have been conducted. Amongst these, the effects of thallium on the contractile force o f isolated myocardial tissues have been studied. Previous experiments were all carried out at concentrations far beyond those encountered during intoxication and yielded controversal data. We therefore reinvestigated the effects of thallium on myocardial tissue at levels between 10 -8 and 10-3 ᴍ, thus covering the range o f thallium concentrations encountered after uptake from a polluted environm ent through those seen after unintentional or intentional ingestion to levels at which previous studies were performed. Sheep interventricular cordis muscles were used at a stimulation frequency of 0.4 Hz showing three types of responses to thallium exposure. From a total of 32 experim ents in 15% of all cases thallium caused a persistant increase in contractility which tended to decrease with time and thallium concentration but always remained greater than the control value. 50% of the experiments showed a progressive loss of contractile force with time and thallium concentration, despite transient increases in contractility which lasted for only 2-5 m in after the application of each new thallium concentration. A combination o f these types of reaction was observed in the remaining experiments in that at low thallium concentrations myocardial contractility increased considerably but then decreased progressively with time and thallium concentration. Guinea pig papillary muscles were used to test one thallium concentration only for up to 75 min. At 10 -8 ᴍ there was no effect, at 10 -7 , 10 -6 , 10 -5 ᴍ Tl + there were positive inotropic transients follow ed by an inotropic decay; at 10 - 4 M Tl + only a progressive decrease of contractility was observed. The relationships between time and thallium concentration at different rates of stimulation were examined in two series of experiments at 0.1, 0.2, 0.4, 1.0, and 2.0 Hz. The effects of thallium were accelerated with increased beating rate and the decay o f contraction also proceeded to markedly lower levels. In the rested state, thallium was also very effectual; this was illustrated in two series o f experiments in which after 10 min intervals of quiescency 15 or more test stimuli were applied at different beating rates (0.1 to 2.0 Hz). The configurations of the resulting staircase phenomena were analyzed with respect to control behaviour for each frequency of the test stimuli and for each thallium concentration. These results suggested an involvement of the slow inward current. The steady state values after quiescency showed a pronounced thallium-induced decay similar to that obtained at high constant stimulation rates. The effects are discussed in terms of distortion of cellular energy production by thallium.

The disrhythmic effects of thallium were investigated in various cardiac tissues to determine the primary site of intoxication with respect to ensuing arrhythmias. In isolated cardiac tissue Lameijer and van Zwieten [1] had contended that arrhythmias arise from the sinus node after thallium poisoning. To test this hypothesis we administered concentrations of Tl + between 10" 7 and 10 -4 ᴍ to guinea pig sino-atrial preparations, to guinea pig papillary muscles and to sheep cardiac Purkinje fibres. In sino-artial preparations thallium provoked increases and decreases of spontaneous beat frequency which were not linked to corresponding changes in contractile force. In conductive tissue, Purkinje fibres, the inactivation kinetics of the fast sodium current and the pacemaker current i K2 were investigated by voltage clamp experiments. Here, thallium was seen to be essentially without toxic effects which could account for arrhythmias. In ventricular muscle actions potentials and contractile force were recorded simultaneously. Here again, ventricular arrhythmias are not to be expected from thallium intoxication in rather high concentrations. The findings support the view that arrhythmogenic effects of thallium are restricted to the sinus node.

To conclude our investigation of thallium effects on cardiac tissues, we studied the slow inward current of sheep cardiac Purkinje fibres exposed to 10 -7 to 10 -5 ᴍ Tl + for extended periods of up to 80 min. Our previous results had suggested a possible involvement of the slow inward current during thallium intoxication: a) the modification of contractility staircases observed during thallium exposure, b) action potential recordings of ventricular muscle, c) changes in spontaneous beating in sino-atrial preparations. The thallium levels chosen were between those yielding strong positive inotropic transients and those producing a marked long­term decay of contraction force. The slow inward current was measured using a conventional two-microelectrode-technique and the standard voltage clamp protocol for this current system. The experimental work was restricted to the determination of d ∞ , the kinetics of activation of the slow inward current and of ī si , the current voltage relation of the current system. This was necessary since the effects of thallium were known to be short-lived and therefore frequent repeat runs of the voltage clamp program had to be performed in order to obtain the time courses of possible transient changes. The results showed that the slow inward current was first increased and then declined at the low concentration of 10 -7 ᴍ Tl + . At 10 -5 m Tl + the initial increase was smaller, whereas the decay of the slow inward current proceeded to lower values. Comparison with contractility measure­ments at the same concentrations of thallium showed a distinct parallelism between changes of the slow inward current and myocardial contractility. Despite this apparent relationship, we do not conclude that the contractile events are primarily a result of changes of the slow inward current, since thallium does not seem to specifically alter the parameters of the slow inward current at the membrane level.

Asexual spheroids of the multicellular green alga Volvox are composed of two types o f cells: non-flagellated reproductive gonidia and Chlamydomonas-like flagellated somatic cells. They are committed by a differentiating cleavage during embryogenesis. The gonidia of the adult spheroids form a symmetrical pattern consisting of four layers of four gonidia each; their position is established already in the embryos by the gonidial initials. Whereas, generally, the 16-gonidia pattern is assumed to be the basic one, most o f the spheroids have fewer gonidia (down to 8). The nine possible gonidial patterns (8 to 16 gonidia) are described and correlated to the gonidial stem cells which have been differentiated. Defects in gonidial pattern are of particular interest, since any model of differentiation has to explain not only the basic pattern formed, but also its systematic variations. Our study shows that the pattern reduction is by no means random, but governed by an intrinsic mechanism which shifts the first unequal cleavage from the 32-celled stage to the 16-celled stage. All the patterns formed can be deduced from cleavage pathways involving non-synchronous differentiation of the stem cells. Thus, pattern formation can be correlated to timing and spacing signals regulating events during embryogenesis.

One of the distinctive features of a biological system is its remoteness from equilibrium: for the treatment of the information exchanged by these systems with the external world the concept of information amount is not sufficient because for nonequilibrium systems we need further specifications about information, i. e. its value. We defined the information value for a genetic code. The comparison of the results we had applying such a definition to the three genetic codes found in nature shows that our definition described the system of transmission and reception of information in a biological organism very well and that the information value of a genetic code can be considered as an index of its efficiency, i.e. of its ability to minimize the effects of a mutation of the genotype on the phenotype. Otherwise, our results show that the information value, and hence the efficiency of the three known codes is the same and suggest that the prerequisite of the evolution of the codes is the preservation of this value.

B-decachloro-o-carborane derivatives in which one of the carbon atoms was substituted by -CH 2 CH 2 CO 2 H (I), -CH 2 CHOHCH 2 -O-CH 2 CH=CH 2 (II) and -CH 2 CHOHCH 2 -O-p-C 6 H 4 NHCOOC(CH 3 ) 3 (III) were prepared from decachloro-o-carborane and the corre­sponding bromo (I) or epoxi (II and III) derivatives under alkaline conditions. II could be epoxidized and bound to dextran, Concanavalin A, and human IgG, with a boron content of 4.3, 4.8. and 4.9% (w/w), respectively. III could be converted to the corresponding amine and further to the isothiocyanate. Such boron derivatives could be suitable compounds for neutron capture therapy of tumors, as they are well water soluble and could be attached to tumor spe­cific antibodies.

In the green coloured larvae of Micromata rosea but not in adults temperature raise above 29 °C causes immediate colour change: green to bluish-green. Colour change is reversible by temperature decline below 29 °C. Qualitative analysis of the yolk pigment reveals the same biliverdin conjugates (micromatabilin) as previously identified for adult spiders. The bluish-green colour (above 29 °C) re­sults from an absorption band (675-680 nm, water phase, purified solution) modified to that of the green solution (below 29 °C). Presumably, the thermodependent, rever­sible colour change is due to a special yolk protein bond to the micromatabilin chromophor.

Gibberelline, prednisolon and benzpyrene stimulated the growth of Tetrahymena at the first interaction, while epinephrine did not. On a second exposure following upon the first 24 h treatment after a rest period of 6 h, epinephrine, too, developed a stimulatory action, and the other three molecules gave rise to a still greater increase in the growth rate. Obviously, imprinting effected by the first interaction accounts for a greater responsiveness to physio­ logical materials (hormones) also if these are indifferent in respect of the given function, and non-physiological, but biologically active materials can also give rise to imprinting in exposed target cells.

The properties of human nerve grwoth factor (NGF) from Glandula submandibularis were examined and char­ acterized. The results closely resemble those of NGF from bovine and swine.

A means was devised to visualize the retinal receptive fields in time and space using the noise on unused television channels as spatio-temporal inputs and performing correla­ tion between the input and output photographically. The method was applied to characterize the receptive fields of catfish retinal ganglion cells. The results were 1) there were two major types of receptive fields, circular and elliptical, 2) shapes and sizes of the field components changed with time (latency), and 3) a field's surround was often localized as hot spots.

Ultrastructural features of the ciliate Hypocoma acinetarum, an ectoparasite of the suctorian Ephelota, led to the conclusion that the Hypocomidae do not belong to the Cyrtophorida, as some authors suggested, but should be reunified with the Ancistrocomidae in the taxon Rhynchodida (Chatton et Lwoff).