Band 29, Heft 3-4

Lamiid and three new iridoids have been isolated from Duranta repens. The new compounds - durantosid I (2), I I (3) and I I I (4) - are shown to be esters of lamiid with cinnamic acid, 4-methoxy-cinnamic acid and 3,4-dimethoxy-cinnamic acid respectively. The position of the cinnamoyl-groups has been determined by NMR-and mass spectrometry.

The small-angle X-ray scattering of 1/10-size molecules (in 0.1 ionic strength Tris buffer pH 8.1) and 1/20-size molecules (in 0.1 ionic strength ethanolamine buffer pH 10.6) of α-hemocyanin of the snail Helix pomatia was studied. The radii of gyration, 8.7 nm and 8.0 nm for 1/10-size and 1/20-size molecules respectively, and the shape of the scattering curves indicate that both have a very anisotropic shape. Comparison of the experimental scattering curve of 1/10-size molecules with theoretical scattering curves gives the best agreement for flat cylinders or quadratic prisms the diameter respectively side of which is about 10 times larger than the height (dimensions side = 21 nm, height 2 nm). The scattering curves of various models composed of larger and smaller subunits were calculated; the best agree­ment was found also for flat models of similar dimensions.

Molecular complexes in the ratio 1:1 were formed in aqueous solution between various methoxysubstituted phenylisopropylamine (amphetamine) hydrochloride or oxalate salts and riboflavin deri­vatives (flavin mononucleotide and flavin adenine dinucleotide). The association constants for these complexes were determined by the fluorescence quenching method as well as by the absorption method. The nature of the complex formation may be due to charge-transfer, electron-transfer, electrostatic and hydrophobic forces. The steric effect also plays an important role in the complex formation. The absorption wavelength and association constant of the complexes are correlated with the published biological activities of the methoxyamphetamines.

Proflavine, DNA, Electron Microscopic Study The conformational changes suffered by full-length double-stranded DNA molecules from bac­ teriophage T7, due to their binding with the mutagenic dye proflavine (PF), has been studied by electron microscopy. The dye-bound DNA showed a smoother contour and a more compact con­ figuration in comparison with the dye-free native DNA. These changes resulted from the stretching, extension and charge-neutralization accompanying the incorporation of PF.

The thermal denaturation of the native DNA in solvents of varying salt concentrations was studied by viscometric and spectrophotometric methods. It was observed that within the molarity range of 0.02 ᴍ to 0.3 ᴍ, the melting temperatures obtained by the two independent methods agreed well, but that at lower ionic strength the agreement was not satisfactory. Both the visco­metric and the spectrophotometric measurements showed an increase of the melting temperature with increasing counterion concentration and a levelling off effect in the neighbourhood of 0.3 ᴍ.

The binding of proflavine to native DNA increased its stability against thermal denaturation as measured by viscometric method. Up to a moderate ionic strength of 0.058 ᴍ, the melting temperature of the complex increased almost linearly with the increase of dye concentrations and a saturation was reached when one proflavine molecule was added per four to five DNA-Phosphates (D/P≅0.2). The extent of stabilization (ΔT m ) produced by dye binding decreased gradually with the increase of ionic strength and no stabilization effect was observed at an ionic strength of about 0.3 ᴍ. The maximum melting temperature attained by Proflavine binding was almost independent of the ionic strength of the medium. The same maximum value was reached as obtained simply by increasing the sodium ion concentration.

Dibenamine, Trypsin Dibenamine (N ,N-dibenzyl-β-chloroethylamine) a potent adrenergic blocking agent inhibits trypsin in an irreversible manner. Electrophoresis and peptide mapping (finger printing) have shown significant changes in the number of peptides and their mobility.

A method is described for the estimation of the uracil content in biological materials by means of high-pressure liquid chromatography. Hydrolysis of the tissues and total liberation of RNA bases are carried out in 70% perchloric acid. Less than 1 mg of the materials are needed for analysis. A pre-purification of the hydrolyzates is carried out by anion-exchange chromatography. Recoveries are estimated by isotope dilution analysis with [2- 14 C] labelled uracil. The method is highly sensitive - about 6000 pmol of uracil content can at least be estimated quantitatively - and analysis time is short. In routine analysis a single sample needs 4 hours to be completed. When preparing several samples at a time an analysis is completed every 45min.

Blue light induces in etioplasts of Hordeum seedlings parallel to the formation of chlorophyll an increased synthesis of carotenoids, plastidic benzoquinones and vitamin K 1 . 1. Blue light induces an enhanced synthesis of β-carotene, lutein, violaxanthin, and neoxanthin, while the levels of antheraxanthin and zeaxanthin are decreased. 2. In contrast to the etiolated tissue a much higher portion of total plastoquinone-9 (oxidized and reduced form) is formed in blue light than total α-tocopherol (+ α-tocoquinone), and a higher portion of the oxidized quinone forms plastoquinone-9 and α-tocoquinone. 3. The blue-light-induced changes of the isoprenoid lipid synthesis described here are similar to those obtained in continuous far-red light. It is, therefore, suggested that blue light is effective via the blue absorption bands of the phytochrome system. 4. Blue-light-induced greening of etioplasts results in a much higher synthesis rate of chlorophyll a and other isoprenoid thylakoid lipids as compared to red light. This enhancement of thylakoid lipid formation appears to be a special blue light effect.

The pH dependence of the receptor potential (ReP) of isolated layers of photoreceptor cells from the hermit crab compound eye (Eupagurus bernhardus L.) was determined. Measurements were performed, using extracellular electrodes, in the range pH 3.5 - 9.5 in three different buffer systems: Tris, glycine, and phosphate. The amplitude of the ReP was highest at pH 7.5 and decreased in more acidic and more alka­line salines (Fig. 4). Relative to the changes in ReP amplitude, the changes in time course and shape of ReP were small. Salines of pH other than 7.5 caused an increase of the latent period but decreased the peak amplitude time and the repolarizing phase (t 2 ). Alkaline salines caused about the same changes in the ReP as acidic salines. The only observed difference was that repolarisation was more strongly influenced by alkaline solutions and that the plateau magnitude was depressed relatively more than the peak magnitude in acidic environments. Of the three buffers used, Tris had the weakest influence on the ReP and phosphate buffer the strongest. In contrast to the good reproducibility of the experimental results, the reversibility of the pH effects was generally poor; the effects with glycine-buffer were more reversible than those with Tris.

Male blackbirds (Turdus merula) were confronted with recordings of normal and experimentally modified song-phrases of their own repertoire. I tested the characteristics of the equivalent vocal responses (= stimulus A → vocalization A) of the birds. As I found the "right" (= the indivi­dually known) syntax (= sequential order) of the elements (= notes) of the phrases were an essential condition for these responses. The different elements (notes) of a phrase took part in the facilitation of the vocal responses particularly (Fig. 1A) . - Phrases modified in their syntax proved to be ineffective in the above mentioned sence; even if the modification remained inside the conspecific range of individual differences between blackbirds. The onset of the ineffectiveness started at that point of the stimuli at which the syntactic modification began (Fig. 1 B, C). However, after an experimental period of 20 days most of the modified phrases (presented to the birds about 100 times per day) began to become effective, that means: to facilitate equivalent vocal responses (Fig. 2). - I concluded that the birds possess a "syntactic filter" which interacts with the genera­ tion of specific vocal reactions on the auditory stimuli. The results show that this filter can be modified.

A method is presented permitting the qualitative and quantitative determination of all three presently known hormones (JH1-3). The determination is based on the method of radioactive isotope dilution, whereby a very small known amount of tritium-labelled JH-1 is added to the ether extract of the particular species. The addition of radioactive JH-1 permits the isolation of all three hormones, because of their similar behaviour during the chosen work up. The quantitative determination was carried out by gas chromatography and the identification was confirmed with the help of retention-times and GC-MS combination. The method was checked by using an extract of Hyalophora cecropia. For the first time methyl 10,11-epoxy-3,7,11-trimethyl-2-trans-6-trans-dodecadienoate (JH-3) could also be identified as the juvenile hormone of Melo­lontha melolontha. In Vanessa io larvae, Tenebrio molitor larvae and adults and in Musca domestica larvae none of the three known hormones could be detected. The preparation of JH-1 labelled with tritium in the methyl group of the ester was accomplished with very high specific activity (4.34 Ci/mmol) of the tritiated acid with diazomethane.

Embryonic rat fibroblasts which have been stopped in G 1 by incubation in serum-free medium can be triggered to proceed through their cell cycle by the serum proteins S1 and S2. To determine the specificity of these serum factors, a wide variety of compounds have been tested: Proteolytic and lipolytic enzymes, hormones, serum proteins, prostaglandins etc. Slight effects could be de­tected with α 2 -Macroglobulin-Schultze and Prostaglandin F 2α in combination with insulin. Stimulation of the cells comparable to that obtained with S1 can be achieved by treating the cells for 10 min with low concentrations of trypsin followed by incubation in serum-free medium containing insulin. The effect of trypsin can be completely abolished by soybean trypsin inhibitor.

DNase treatment of Ehrlich ascites tumor cells releases DNA fragments from the membrane surface. This increases the capacity of the cells for homoribopolynucleotide uptake. Another portion of membrane DNA is embedded in protein structures and is not accessible for DNase. This DNA does not hinder ribopolynucleotide uptake unless it is unwrapped by a sub­ equent pronase treatment of the cells. We interprete these findings to be the consequence of alterations of the net negative charge brought about by the removal and reestablishment of "open" surface DNA.

D-Sesamin, Phyllarthron comorense, Mass Spectrum The petroleum ether extract of the heartwood of Phyllarthron comorense DC affords D-sesamin along with paulownin, lapachol, dehydrotectol, dehydro-a-lapachone, /Mapachone, tectol and /5-sitosterol1. We have earlier communicated the mass spectrometric studies of dehydro-a-lapachone2 and paulownin3. The present work deals with the formulation of pos­ sible fragmentation schemes in the case of D-sesamin. This compound is a member of 3,7-dioxabicyclo-Table I. Mass spectral data of D-sesamin a. S. No. m\e Ion composition Relative intensities