Volume 35, Issue 5-6

Formulas proposed for the mineral of bone were reviewed. Literature data were collected where Ca, P, Na, Mg and CO3 are determined in the same samples. These data were analyzed for their conformity to the above mentioned formulas. According to this analysis Mg is contained in a phase having the Ca/P of magnesium whitlockite within the limits of error. Na is contained in a carbonated calcium phosphate phase which in analogy with synthetic systems must have the apatite structure. The Ca/P ratio of the remaining "rest phase" is 2. This is based on the composi­ tion of 101 bone mineral samples taken from fishes, reptiles, amphibians, birds and mammals. The CO3 content of the bone samples agrees with the formula Ca8 (PO4)4 (CO3) (OH)2 · x H2O for the "rest phase" within the limits of experimental error. Such a compound has, however, not been found in synthetic systems. Human bone contains about 15% magnesium whitlockite, 25% of the Na and CO3 containing apatite and the rest is the carbonated calcium phosphate with Ca/P = 2. It is presumed that this compound has a structure similar to that of octo calcium phosphate and that most of the citrate ions which always occur in bone mineral samples are in­ corporated in that phase.

Tropoyl coenzyme A has been synthesized in good yields via the corresponding N-hydroxysuc-cinimide ester. The UV-spectrum of the purified thioester has an absorption maximum at 257 nm; at this wavelength, a molar extinction coefficient of 19.2 × 106 [cm2 mol-1] has been determined. Upon alkaline hydrolysis of the thioester bond a difference spectrum with Amax at 235 nm (Δe235= 4.8 × 106 [cm2 mol-1]) has been observed. Attempts to prepare 2-phenylmalonyl coenzyme A by the same technique gave negative results.

An extensive study of the chiroptical properties of C-phycoerythrin and the α-and β-subunits in the spectral region from 700 -200 nm is presented. Based on the VIS-circular dichroism inherently chiral conform ations are proposed for the co­ valently linked chromophores. By means of mean residue ellipticities and the experimental circular dichroism spectra in the region of the n → π* peptide transition the a-helix contents of the apoproteins of the ac-and ß-subunits are estimated to amount to 60% and 40%, respectively. The circular dichroism spectrum of native C-phycoerythrin is congruent with a linear superposition of the α-and β-subspectra, in the whole spectral region studied. Since a-and β-subunits are associated in native C-phycoery-thrin as revealed by sedim entation analysis the interactions between the subunits in the native chromoprotein are not accom panied by substantial conform ational changes. In the temperature range 0°-40°C the thermally induced changes of the chrom ophores in native C-phycoerythrin are not associated with changes of the secondary structure of the apoprotein. Unfolding occurs at 60°-70°C but slowly leads to irreversible denaturation. Protein unfolding starts at 3 M urea. The random coil secondary structure of the apoproteins is reached at 8 M urea. At this concentration the absorbance and the optical activity of the chrom o­ phores are reduced by a factor 3 and 10, respectively. The conformational changes in the peptide with increasing denaturant concentration are not synchronous with those induced in the Chromo­ phore indicating that a m ultistep process is operative during unfolding. The C D results on dena­ turation are supplem ented by absorption and em ission spectroscopy.

The skin of Helix pomatia was investigated by biochemical methods and electronmicroscope. Biochemical investigations showed that Helix pomatia collagen represents a methionine-lacking collagen resistant to CNBr-cleavage. Electron microscopic studies showed a cross striation pattern of 5 3 -5 7 nm.

Medicago x varia Martyn c. v. Cardinal (Fabaceae) The Seed-Flavonoids of Medicago x varia Martyn c. v. Cardinal (Fabaceae) Medicago x varia c. v., Fabaceae, Flavonoids, 5-Methoxyflavones, 5-Methoxyflavonols From the seeds of Medicago x varia Martyn c. v. Cardinal have been isolated twenty flavonoids, including four 5-methoxyflavonoids. Four compounds have been obtained the first time from a natural source. The constitution of all compounds is prooved.

Two new phytoalexins isolated from the fungus-inoculated leaflets of Erythrina sandwicensis have been identified as (—)-6aS; 11 aS-3,6 a,9-trihydroxy-10-isopentenylpterocarpan (sandwicar-pin) and (—)-6aR; 11 aR-3-hydroxy-9-methoxy-10-isopentenylpterocaipan (sandwicensin). These compounds co-occur with several known pterocarpan (demethylmedicarpin, 3,6a,9-trihydroxy-pterocarpan, phaseollidin and cristacarpin) and isoflavan (demethylvestitol and isovestitol) deriva­ tives. The preparation and spectral (UV, MS) characteristics of 3-methoxy-9-hydroxy-10-isopen-tenylpterocarpan are also described.

Injections of radioactively labelled calliphorin into Illrd instar larvae of Calliphora indicate that the protein is incorporated into the integument. Immunofluorescence techniques show that the endocuticle is the Final site of deposition of calliphorin. It is concluded that calliphorin is an essen­ tial protein of the tanned cuticle.

Traps baited with 100 μg (Z)-9-dodecenyl acetate and 10|ig (Z)-ll-tetradecenyl acetate are highly effective in attracting C. murinana males at varying population densities. The attractive mixture was established by electrophysiological and Field screening studies combined with chemical analysis of the female pheromone secretion. (Z)-9-dodecenyl acetate is a major constituent in washes of pheromone glands of calling C. murinana females. This compound, the first dodecenyl ester pheromone known for a species of the Archipini tribe, is moderately attractive on its own at low doses. Attraction is strongly synergized by 10% (Z)-11-tetradecenyl acetate but is inhibited by small amounts of (Z)-9- tetradecenyl acetate. Each of the three compounds acts upon a separate type of receptor cell in hair sensilla of the male antenna.

The degradation of 3,9-dimethoxypterocarpan was investigated in selected strains of Fusarium. Fusarium proliferatum (i. e. Gibberella fujikuroi (SAW)WR) degrades this substrate via 3-meth-oxy-9-hydroxypterocarpan, 3,9-dihydroxypterocarpan and 2',4',7-trihydroxyisoflavan. During degradation by this organism medicarpin is first demethylated to 3,9-dihydroxypterocarpan.

NAD-specific glutamate dehydrogenase [L-glutamate: NAD + oxidoreductase (deaminating) EC 1.4.1.2] from Medicago sativa constitutes organ-specific patterns of isoenzymes. The isoenzyme-pattems of seeds (GDH-I) and roots (GDH-II) were purified 1520-fold and 92-fold, respectively. All isoenzymes of both patterns remain stable throughout the purification procedures. Isoenzyme a7, the only isoenzyme common to both patterns was isolated from the GDH-I pattern. The three enzyme preparations were found to be identical in pH optima, substrate specificity and general kinetic properties. A comparative kinetic analysis revealed no pronounced differences between the various kinetic constants evaluated for the three enzyme preparations. Furthermore an identical order of substrate binding and product release could be established. Both initial rate measure­ ments and product inhibition studies are consistent with an ordered ternary-binary kinetic mecha­ nism. The results suggest that tissue-specific enzyme multiplicity of plant glutamate dehydrogenase is not related to differences in general or kinetic properties.

The Stimulation of the carboxylase reaction by effectors of ribulose 1,5-bisphosphate carboxyl­ ase/oxygenase displays higher sensitivity towards pyridoxal 5'-phosphate inhibition than the catalytical process itself. Pyridoxal 5'-phosphate binding to the enzyme is not affected by the modulators 6-phospho-gluconate and fructose 1,6-bisphosphate at low concentrations at which these agents stimulate the carboxylation rate. At higher concentrations these sugar phosphates protect the enzyme against pyridoxal 5'-phos-phate inhibition in a similar fashion like the substrate ribulose 1,5-bisphosphate. Such protection experiments in combination with spectrophotometrical studies of pyridoxal 5'-phosphate binding demonstrate two binding states of ribulose 1,5-bisphosphate at the reaction centers of the enzyme with different requirements for Mg2+. 6-Phosphogluconate functions as protector only in the presence of Mg2+. Our results imply a competition between pyridoxal 5'-phosphate and substrate or effector sugar phosphates at the reaction centers of the spinach carboxylase. It is proposed that the pyridoxal 5'-phosphate inhibition of the stimulatory activity of these effectors originates from a modification of the regulatory sites of the enzyme caused by pyridoxal 5'-phosphate binding to the catalytical sites.

Levels of cyclic adenosine monophosphate (cAMP) have been determined in the green alga Chlamydomonas reinhardtii strain CW 15. In the early exponential growth no cAMP was detected, however, in the middle of the exponential growth phase 2.4 pmol cAMP/mg protein were found and the cAMP level increased to 18.8 pmol/mg protein in the stationary phase. An enzyme fraction has been isolated from Chlamydomonas, which produced cAMP in vitro using adenosine-5'-phosphosulfate (APS) as a substrate. This protein fraction was isolated by am-moniumsulfate precipitation, DEAE-cellulose chromatography and Sephadex-G-100 gel filtration. A solvent system was developed for thin layer chromatography to separate cAMP from APS, adenosine-5'-phosphoramidat (APN), 5'-AMP and adenosine. The product was identified as cAMP by cochromatography, coelectrophoresis, treatment with phosphodiesterase, chromato­ graphy on Biorad-columns and by the protein-binding assay. The so far purified protein fraction produced 151 pmol cAMP/mg protein and hour in vitro, using APS as a substrate.

ATPase activity and ATP-Pi exchange of unregulated (without tropomyosin-troponin) and regulated (with tropomyosin-troponin) acto-HMM were measured in media containing 0.2 mg/ml actin, HMM, and (when present) tropomyosin-troponin, 2 mM MgCl2, 10 m M KCl, 2 mM NaN3, 10 mM Pi(pH 7.0), 3 mM ATP. The following mean values for ATPase activity and for the rate of incorporation of P, into ATP (each per mg HMM and per min) were obtained: unregulated acto-HMM 0.33 nmol Pi and 0.33 nmol Pi, regulated acto-HMM 0.54 nmol Pi and 1.06 nmol P*. The ratio of P4 incorporation rate to ATPase activity was 1.01 × 10-3 for unregulated and 2.02 × 10-3 for regulated acto-HMM. From these ratios and from the overall free energy change of ATP hydrolysis it was calculated that under the prevailing experimental conditions in unregulated acto-HMM 62% and in regulated acto-HMM 66% of the free energy change of ATP hydrolysis occurs after the release of phosphate from actomyosin. It is probably this part of the free energy change that is used by the muscle for the performance of work.

Batch cultures of the phototrophic bacterium, Thiocapsa roseopersicina, were grown anaero­ bically in the light either on sulfide with various ammonia concentrations, N 2 or amino acids as nitrogen sources, or on several simple organic substrates in the absence of reduced sulfur com­ pounds using 6 mM NH4Cl as source of nitrogen. At high ammonia concentrations high activities of (NADPH-linked) glutamate dehydrogenase (GDH), but rather low transferase and no bio­ synthetic activity of glutamine synthetase (GS) were obtained, while under conditions of ammonia deficiency (growth with N 2 or glutamate) GDH activity was very low and both GS activities were strongly increased. Glutamate synthase (GOGAT) activity (NADH-dependent) showed little variation. These data indicate that at high NH+ concentrations ammonia is assimilated via GDH, under NHJ limitation, however, via the GS/GOGAT system. Glutamine as nitrogen source may be utilized via GOGAT as well as via an active glutaminase plus GDH. Ammonia, but not glutamine, seems to cause repression and inactivation of GS. Alanine and asparagine inactivate the enzyme inhibiting the biosynthetic, but not the transferase activity. These amino acids in part also influence the activities of GDH, GOGAT, malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICDH). Cultures grown on acetate or pyruvate instead of sulfide showed increased GDH activities and high GS transferase activities possibly reflecting an increase of intracellular a-ketoglutarate concentration. On malate or fructose also increased GS transferase activities, but rather low GDH activities were observed. High biosynthetic GS activities and elevated GOGAT activities were found only in fructose-grown cells. On the organic substrates the ICDH activities always were somewhat higher than after lithoautotrophic growth. With the exception of acetate, the MDH activities were considerably elevated, especially on pyruvate. The different pathways of ar-keto-glutarate formation and their influence on the enzymes of ammonia assimilation are discussed.

Etioplasts of radish seedlings treated with photosystem II (DCM U, bentazon) and chlorotic herbicides (amitrole, SAN 6706) were tested on their ability to perform the phytochrome mediated chlorophyll and carotenoid biosynthesis. The cytoplasmic influence on the chloroplastic action of herbicides was also investigated by inhibition of protein synthesis either in the chloro­ plast with chloramphenicol or in the cytoplasm with actidion. In all herbicide treated radish seedlings a phytochrome mediated chlorophyll and carotenoid biosynthesis was obtained as found in control plants. In plants treated with DCM U the bio­ synthesis of carotenoids is enhanced compared to the control plants, while SAN 6706 significantly suppresses the carotenoid formation. It is concluded, that photosystem II and chlorotic herbicides do not interfere with the primary action of phytochrome but rather do develope their effects on the terpenoid metabolism through phytochrome. Chloramphenicol applied at the time of sowing very strongly suppresses the formation of chlorophylls and carotenoids in control plants. The sensitivity towards actidion is, however, very much lower. If chloramphenicol and actidion treated plants were also supplied with herbicides, the pigment pattern is completely different In SAN 6706-treated plants chloramphenicol acts synergistic, resulting in an even lower chlorophyll and carotenoid content than in plants supplied only with chloramphenicol. On the other hand SAN 6706 in combination with actidion enhances the formation of pigments, leading to a much higher chlorophyll and carotenoid content as in plants treated only with actidion. A stimulatory effect on the formation of chlorophylls and carotenoids was also found for DCMU-treated plants in combination with actidion. The observation, that in plants treated with SAN 6706 together with actidion, which inhibits protein synthesis in the cytoplasm, the herbicidal response in the chloroplast is completely abolished, gives evidence that the photooxidative action of SAN 6706 in the chloroplast is developed by the cytoplasm.

The effect of NH4Cl on the kinetics of the back reaction of photosystem II as derived from luminescence measurements was investigated in dark adapted Chlorella in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) at different temperatures. The kinetics of the back reaction which, under these conditions, leads to the reduction of the S2 state by the primary electron acceptor Q- of photosystem II was observed to be considerably slowed down in the presence of NH4Cl. Analysis of the kinetic results in the light of the theory of the back reaction developed by Mar and Roy (J. Theor. Biol. 48, 257-281 (1974)) revealed two opposite effects of NH4Cl to be present simultaneously: 1) The enthalpy of activation of the back reaction was lowered (catalyzing effect of NH4Cl) 2) The frequenca factor which indicates the number of collisions of the reacting molecules in the membrane per second is largely decreased (inhibitory effect of NH4Cl). This reduction of the mobility of the recombining species of the back reaction is the predominant effect of NH4Cl. It is suggested that this effect is due to a change of the conformational state of the membrane induced by dissolution of relative large amounts of NH? within the lipid phase of the thylakoid membrane. This hypothesis is supported by the observation that the value of the exciton yield of the back reaction changes upon addition of NH4Cl.

The mykotrophic orchid Neottia nidus-avis does not evolve oxygen in the light but is able to perform photophosphorylation. The low temperature fluorescence emission spectrum lacks the 680 and 690 nm bands. Hence, the spectroscopic chlorophyll a forms which are attributed to photosystem II do not occur in plastids of this orchid. The low temperature excitation spectrum of photosystem I fluorescence exhibits a maximum at 666 nm. The position of this maximum appears not to be influenced by energy transfer and corresponds to the absorption maximum of the chlorophyll form which emits the photosystem I fluorescence. Energy migration, however, occurs from carotenoids whose absorption spectrum is shifted to longer wavelengths and which cause the yellow-brown color of the Neottia plastids. Room temperature fluorescence emission shows after the onset of light no variable part. Despite the fact that plastids of the tobacco mutant NC 95 at most evolve only traces of oxygen the low temperature emission spectrum shows the three bands which are usually observed with fully functioning chloroplasts. However, the two bands at 680 and 690 nm are distinctly lower than with the wild type. The variable portion of room temperature fluorescence is barely detectable. In line with the very low capacity for oxygen evolution, rates of electron transport partial reactions in the region of photosystem II are extremely low. In agreement with this observation no 690 nm absorption change signal is detected. However, a normal P+700 signal is seen. In the presence of electron donors like reduced phenazine methosulfate the decay time of the P+700 signal is faster than with the wild type. The yellow tobacco mutant Su/su var. aurea which exhibits at high light intensities higher rates of photosynthesis than the wild type shows at low temperature an emission spectrum with stronger photosystem II bands than the wild type.

By staining of cryo-sections of rat liver with a fluorescent phallotoxin, the distribution of filamentous actin in liver cells could be demonstrated by fluorescence microscopy. While in untreated livers filamentous actin forms an almost continous layer at the cell periphery, the poisoning by phalloidin leads to the formation of actin clusters, preferentially located near the cell membrane.

K3(Mn-(III)-chlorin e6) acetate, a water-soluble chlorophyll derivative with manganese as central atom was prepared. The influence of reducing agents, light, and bicarbonate on the oxida­ tion states of manganese in the chlorin complex was investigated. In alkaline solutions the central Mn3+ was reducible to Mn2+. The illumination of the partially reduced complex first accelerated the reduction (light reduction: Mn3+ → Mn2+), which was then followed by a strong reoxidation (light oxidation: Mn2+ →* Mn3+) continuing after switching off the light. This redox effect of light was obtained only in presence of hydroxylamine as reducing agent. Illumination time, intensity, and frequency had an influence on this effect. In the light/dark change the process was reversible. In regard to the requirement of manganese for the photosynthetic oxygen evolution the observed valence change of manganese in the chlorin complex was compared to the supposed reaction mechanism on the donor side of photosystem II.

The effect of y-ray irradiation and immobilization by means of radiation polymerization on PS II activity (O2 evolution) of isolated chloroplasts from spinach was investigated. Reduction of O2 evolution activity by irradiation was small at lower temperatures below – 24 °C, but the activity decreased slightly by freezing at extremely low temperature below –78 °C. So the optimum low temperature range for the treatment was observed. The immobilized chloroplast in a hydrophilic polymer matrix showed the stable duration of O2 evolution activity more than 700 h at 4 °C . Thermo-stability of chloroplast was also improved greatly by immobilization. The active center of PS II in immobilized chloroplasts was retained even after 60 min standing at 50 °C.

TMV vulgare, A 14, Ni 725; Two-and Three-Layer Aggregates, Structural and Mechanistic Differences, Inter-Subunit Interactions, Non-Specific Aggregations The aggregation behaviour of tobacco mosaic virus (TMV) protein vulgare was compared to that of two mutants, A 14 and Ni725, with amino acid exchanges localized in the coat protein at posi­ tions 107 (Thr → Met, in N i725) and 129 (lie → Thr, in both mutants). This behaviour, as meas­ ured by sedimentation, hydrogen ion titration, light-scattering, and near-UV absorption difference and circular dichroism (CD) spectroscopy, differs characteristically both in the range of the A-protein (pH 8) and near neutrality, whereas nuclear magnetic resonance (NMR) and far-UV CD point at only subtle, or no structural differences between the three strains. Near pH 8, the A-proteins of both mutants sediment nearly exclusively as 8 S aggregates, under conditions where vulgare protein forms a 4 S /8 S mixture (two-layer and three-layer aggregates, Vogel etal. in conditions where vulgare 4S aggregates dominate, both mutants sediment as a 4 S /8 S mixture. The average molecular weights of the 8S proteins corre­ spond to 12 (vulgare) to 15 (mutants) subunits. -Near neutrality both mutants titrate and polyme­ rize more cooperatively than vulgare protein; additionally, the pK(app.) of Ni 725 is shifted up­ wards, due to the higher a-helix forming potential of Met against Thr (pos. 107). Both mutants form large aggregates (> 200 S) of obviously helical conformation, by the uptake of one proton per subunit, whereas 20 S-disks constituting, under the same conditions, the stable entities in vul­ gare protein, are made only in minor amounts. These large mutant aggregates are remarkably more stable than the vulgare "overshoot" aggregates which transiently, too, may approach s-values and turbidities similar to the mutant aggregates; conformational changes, observed prior or in parallel to the formation of vulgare overshoot and disk aggregates, are significantly retarded in the large mutant aggregates. – Raising the ionic strength seems the only way to form mutant disks and stacks of disks (20-30 S) comparable to vulgare, pointing to the different pathways of disk formation, either at neutral pH or high ionic strength. – Evidence is given that the 8S aggregates of both mutant and vulgare proteins may behave similar in aggregation, the differences mainly being inserted by the 4S (two-layer) aggregates present in vulgare protein, which near neutrality seem responsible for the direct formation of (two-layer) disks. -The non-conservative exchange in po­ sition 129, altering the environment of Trp residues (52+17?), should weaken the "extended salt-bridge system" ("pairing") observed between the two layers of the disk (Bloomer et al., Nature, 1978). A competition is suggested between the strength of this pairing, and the binding of a third layer, regulating the mode of aggregation to two-layer, to three-layer, and to higher aggregates; this is corroborated by comparison with published results on temperature-sensitive (ts I) mutants and chemically modified proteins. – To explain the effects of residue 129 on the titration of the protein we suggest a mechanical analogy, made up of a balance between the charge and state of the "carboxyle cage" (Stubbs et al., Nature, 1977), as regulatory site, and the strength of the

The mureinlayerthickness of Spirillum serpens was estimated by means of small-angle X-ray scattering methods using solid preparates of broken cell walls. The interpretation of the scattering curves was possible by application of G. Porod's scattering theory of packings of lamellae.

Lithium carbonate lengthens the circadian period in humans under temporal isolation (arctic summer four groups.

The sequence of a protein can be graphed as a discrete function and a cross-correlation between any two such number sets produces a similarity score. The scores are used to prepare a phylogenetic tree involving hierarchical cluster analysis, non-linear mapping, and minimal spanning routines. Changes are suggested in the sequences of cytochrome c’s from Mediterranean fruit fly, locust, and rattlesnake. The method is faster than existing procedures and does not require human intervention at any stage.

From needles of Larix gmelinii sixteen flavonoids were isolated and identified. The main flavonoids had been analyzed before, eight minor ones were identified as quercetin-3-glucoside, isorhamnetin-3-glucoside and -3-ara-binoside, a somewhat lipophilic kaempferol-3-glucoside derivative, apigenin-7-glucoside, laricitrin-3-rutinoside and laricitrin-and syringetin-3-(p-coumarylglucoside).

A quantitative fluorimetric detection of a-amanitin treated by H3PO" is proposed. Spectra for both amanitin and tryptophan suggest an extended aromatic structure clearly confirmed by JH NMR spectrography.

Prolamellar body tubules in etioplasts are composed mainly of two saponins. The determination of these saponins in leaves, etioplasts or subfractions of etioplasts is recommended to evaluate the concentration of these tubules in a given fraction. Using a densitometer after TLC-separation of the saponins measurements are carried out in a short time with high accurancy. Also the absolute concentration of these saponins can be determined. Problems in the quantification of the saponins in leaf samples can be overcame with filters of different wavelengths.

Yeast tRNAPhe, Yeast tRNATyr, Pyridoxal-5'-phosphate Yeast tRNAPhe and tRNATyr were reacted with the fluo­ rescent reagent pyridoxal-5'-phosphate and the modified tRNAs were analysed with respect to the number and posi­ tion of modified nucleosides and with respect to amino-acylation. a) Following the intrinsic fluorescence of pyridoxal-5'-phosphate, the treatment of tRNATyr with increasing amounts of pyridoxal-5'-phosphate revealed about 50 mol of reagent or a even higher number bound per one mol of tRNATyr. After borohydride reduction (in order to stabilize the linkage) of this modified tRNATyr and purification with reverse phase b) Both tRNATyr and tRNAPhe treated with pyridoxal-5'-phosphate and reduced exhibited almost unchanged aminoacylation as compared to the unmodified tRNAs. c) Pyridoxal-5'-phosphate treated and reduced tRNAPhe and tRNATyr were digested with ribonuclease T1 and the resulting oligonucleotides were separated. However, no flu­ orescent oligonucleotide and no difference to an oligonucleotide pattern obtained from unmodified tRNA were observed. Thus, pyridoxal-5'-phosphate might have been bound to the highly purified yeast tRNAPhe and tRNATyr samples either via an unstable linkage or not covalently. This result is controversial with respect to the specific reaction of pyridoxal-5'-phosphate with unfractionated tRNAs from colon carcinoma and tRNAs from E. coli as reported in the literature.

Procion Brilliant Yellow M 4RAN and Procion Yellow M 4R applied to the catfish olfactory mucosa stain intra-vitally and enter the olfactory receptors by their dendrites. The dye invades the receptor pericaryon and subsequently migrates within the axon in distal direction. Fluorescence microscopy of aldehyd fixed and paraffin sectioned preparations reveals clear selective staining of the sensory neu­ rons in yellow colour.