Volume 32, Issue 7-8

Metallocenes, labelled with 103 Ru, are potential radiopharmaceuticals for use in nuclear medicine diagnosis. Ruthenocene derivatives with oxopropene side-chains were administered to mice and rats to study their biochemical properties. Excretion rates and organ distributions of 103 RuCl 3 and Cinnamoyl-[ 103 Ru] ruthenocene were very different. While 103 RuCl 3 was relatively evenly distributed in the body, the metallocene derivative was concentrated in liver, lungs and spleen after intravenous (i.v.) injection. After i.p. injection however a high thymus affinity was observed and autoradiography proved that the site of 103 Ru accumulation was in thymocytes. The thymus affinity can be diminished by corticoid pretreatment and raised by inhibition of phagocytosis (BeSO 4 ). The mechanism of accumulation in the thymus and a possible clinical application are discussed.

The dependence of G i ( - M) values of histidine on the concentration of irradiated 10 -4 -10 -1 ᴍ solutions, pH and the presence of O 2 , N 2 O and sec-butyl alcohol was investigated. In oxygen-free medium the maximum radiation sensitivity of histidine was found at pH 5 - 8; in oxygenated solutions it was shifted to the 6 - 11 pH range. The formation of radiation products was also studied. The course of radiation decomposition of histidine depends on the presence of oxygen and on the pH of irradiated solution.

The electrochemical reduction of 2-oxopurine in buffered aqueous medium was found to proceed via two successive one-electron additions. The initial one-electron step involves the addition of a proton, leading to formation of a free radical which rapidly dimerizes. At more negative potentials, reduction leads to formation of 1,6-dihydro-2-oxopurine. The product of reduction on wave I was isolated and identified by various spectroscopic techniques as the dimer 6,6′-bis-(1,6-dihydro-2-oxo-purine). In neutral aqueous medium this dimer reduction product (but not the product of reduction on wave II, 1,6-dihydro-2-oxopurine) underwent quantitative photochemical dissociation to the parent 2-oxopurine, with a quantum yield at 254 nm of 0.03. The dimer reduction product also quantitatively regenerated the parent monomer in an alkali-catalyzed reaction at room temperature. The proposed mechanism of the reduction reaction, and susceptibility of the reduction product to photodissociation, is compared with the corresponding behaviour of other purine, and pyrimidine, derivatives.

A new total synthesis of the tetratriacontapeptide amide corresponding to the proposed primary structure of human big gastrin I is described. The synthetic route was based on the preparation of six suitably protected fragments, related to sequence 28 - 34, 23 - 27, 21 - 22, 15-20, 9 - 14, and 1 - 8, to be used as building blocks for the total synthesis. The protecting groups were selected according to the Schwyzer-Wünsch strategy of maximum side chain protection based on tertiary alcohols, also for the imidazol function of histidine. Subsequent assembly of the six fragments by three different pathways using the highly efficient Wünsch-Weygand condensation procedure to ensure minimum racemization, followed by deprotection of the synthetic products via exposure to trifluoroacetic acid and final purification by ion-exchange chromatography on DEAE-Sephadex A-25 and partition chromatography on Sephadex G-25, led to human big gastrin I, homogeneous within the limits of the analytical methods used. The biological activity of the synthetic product proved to be 50 percent higher than that of human little gastrin I. The 32-leucine analogue of human big gastrin I was prepared in the same way.

The EFG-tensor at the position of the Fe-atom of CO-liganded sperm whale myoglobin has been investigated by nuclear γ-resonance absorption experiments on single crystals. In addition the tem­ perature dependence of the quadrupole splitting of the 14.4 keV level of the iron nucleus was measured. An unambiguous solution for the magnitude and the orientation of the field gradient tensor could only be obtained with the assumption that a C 2 -axis perpendicular to the haem plane is one principal axis of the electric field gradient tensor. Within this solution the electronic struc­ture of the iron is described by a singlet ground state with η z = 0.75 and the largest EFG component perpendicular to the haem plane.

The chromophore-protein interactions of C-phycocyanin (C-PC) from Spirulina platensis have been studied by following the partial and complete denaturation with UV-Vis spectroscopy. From comparison with published MO calculations, an elongated conformation of the chromophore is suggested for native C-PC, a cyclic one for denatured C-PC. By means of partial denaturation, a step­ wise unfolding of the protein has been demonstrated. The presence of at least two sets of spectro­ scopically different diromophores is suggested from the partial denaturation and low temperature experiments.

The isolation and identification of 3-methylriboflavine from the toadstool Panellus serotinus is described.

Riboflavin, the biosynthetic precursor of the 5,6-dimethylbenzimidazole moiety of vitamin B 12 , is transformed non-enzymatically into 5,6-dimethylbenzimidazole in small yield on treatment with 1 ɴ or 5 ɴ NaOH at 100 °C. Besides 5,6-dimethylbenzimidazole 1,2-diamino-4,5-dimethylbenzene, 1.2- dihydro-6,7-dimethyl-2-keto-1-ᴅ-ribityl-3-quinoxaline carboxylic acid and N-1-ᴅ-ribitylamino-2- amino-4,5-dimethylbenzene can be detected. When [1′- 14 C] riboflavin is used the 5,6-dimethyl­benzimidazole contains about 75 per cent of the specific radioactivity of riboflavin. N-1-ᴅ-ribityl- amino-2-amino-4,5-dimethylbenzene is transformed into 5,6-dimethylbenzimidazole more efficiently than riboflavin. Oxygen enhances the yield of 5,6-dimethylbenzimidazole and 1,2-diamino-4,5-di- methylbenzene from riboflavin as well as from N-1-ᴅ-ribitylamino-2-amino-4,5-dimethylbenzene. 1.2- diamino-4,5-dimethylbenzene reacts together with formaldehyde but not with formate to form 5,6-dimethylbenzimidazole under alkaline conditions at 100 °C. It is therefore suggested that the nonenzymatic reaction of riboflavin proceeds via N-1-ᴅ-ribityl- amino-2-amino-4,5-dimethylbenzene and 1,2-diamino-4,5-dimethylbenzene, and that the latter reacts with formaldehyde preferably formed by oxidative degradation of C-1′ of the ribityl side chain to form 5,6-dimethylbenzimidazole via its unstable imidazoline derivative. The possible relevance of these results for the enzymatic process is discussed.

The ribose conformations of formycin, 2-azaadenosine, nebularine, 8-bromoinosine, and 8-bromo- xanthosine have been studied using proton magnetic resonance in ND 3 solutions, in D 2 O solutions, and in pyridine solutions. The temperature was varied between - 60 °C and +40 °C in ND 3 and between +10 °C and +60 °C in D 2 O solutions. In solution, 2-azaadenosine and nebularine have a conformational behaviour similar to that of the common purine (β) ribosides. This is in agreement with the conformations observed in the solid state. The conformations of formycin and formycin B have strong analogies with those of the 8-bromopurineribosides and differ significantly from those of the 8-azapurineribosides since they adopt preferentially the syn-S-g + conformation. This con­formation is very probably stabilized by an intramolecular hydrogen bond between O (5′) and N (3).

The Montecarlo method is used to computer simulate a random distribution of molecular lengths generated by inducing T4 DNA fragmentation through the decay of 32 P atoms introduced in the molecule. Taking into account the experimental conditions we find that the value of α for alkali sucrose gradients is 0.46 + 0.02 and does not depend on the running time. Our findings also prove that the computer simulation can be utilized to analyze sedimentation profiles of DNA molecules fragmented in vivo.

Denatured DNA of coliphage Tl, poly-dT and dTpT were UV-irradiated (2537 Å) and con­jugated to methylated bovine serum albumin. These molecules act as haptens after injection into rabbits. Antibodies are predominantly formed against UV-induced cyclobutane-type of cis-syn thymine dimers. They belong to the IgG-type of antibody molecules. Antigen-antibody complexes were detected by means of the CsCl-density gradient method. Denaturation of the DNA strongly influences the amount of specific antibodies bound to the antigen. In native DNA thymine dimers are masked concerning their reaction with antibodies. Photoproducts of UV-irradiated dTpT induce a specific production of antibody. Our results indicate that the cyclobutane type of thymine dimers is the relevant antigenic determinant group in UV -irradiated DNA.

[ω- (3-Acetylpyridinio) -n-alkyl] adenosine pyrophosphates are coenzyme analogs of NAD ⊕ . The adenosine pyrophosphate moiety and the 3-acetylpyridine ring of the analogs are connected by n-alkyl chains of different lengths (ethyl -hexyl). The analogs form strong dissociating complexes with lactate dehydrogenase. The complex formation is predominantly achieved by interaction of the ADP moiety with its respective binding domain at the active site. The redox potentials of the analogs and NAD are of similar magnitude. The coenzyme function of the analogs depends upon the length of the hydrocarbon chain. Lactate dehydrogenase and alcohol dehydrogenases from yeast and horse liver do not catalize hydrogen transfer from their substrates to any other alkyl analog but [4- (3-acetylpyridinio)-n-butyl] adenosine pyrophosphate, aldehyde dehydrogenase from horse liver catalizes hydrogen transfer from acetaldehyde to the pentyl derivative and glyceraldehyde-3-phosphate dehydrogenase catalizes hydrogen transfer to both analogs. In no case, hydrogen transfer from or to one of the 3-acetylpyridine-n-alkyl analogs proceeded with a velocity comparable to NAD or its 3-acetylpyridine analog. The results show that the nicotinamide bound ribose in NAD is involved in the binding and the activation of the coenzyme.

Bacteria with the ability to grow on pyrazon as sole source of carbon were isolated from soil. They also are able to grow on antipyrin. Then three metabolites of antipyrin can be isolated from the culture fluid which were identified as 2,3-dimethyl-1-(cis-2,3-dihydro-2,3-dihydroxy-4,6-cyclo- hexadiene-1-yl) -pyrazolone (5)(I), as 2,3-dimethyl-1-(2,3-dihydroxyphenyl) -pyrazolone (5) (II)and as 2,3-dimethyl-pyrazolone (5) (III), respectively. Compound I and II were used as sub­strates for enzyme studies. A dioxygenase catalyzes the enzymatic conversion of antipyrin into compound I. In the presence of NAD as cosubstrate compound I is transformed into compound II by a dehydrogenase. A pure preparation of metapyrocatechase from pyrazon-degrading bacteria converts compound II into the dephenylated heterocyclic moiety of antipyrin (III) and into 2- pyrone-6-carboxylic acid. Based on the results of the enzymatic studies a pathway for the degrada­tion of antipyrin is proposed.

A downfield shift of proton signals up to 9 ppm is induced in the 1 H NMR spectra of juvenile hormone I (methyl 3,11-dimethyl-10,11-cis-epoxy-7-ethyl-2-trans, 6-trans-tridecadienoate) and III (methyl 10,11-epoxy-2-trans, 6-trans-farnesoate) by the lanthanide complex Eu(fod) 3 . A plot of induced shift vs the ratio of [LSR]/[substrate] shows a good linear correlation for the range 0.3 -1.0 mole ratio. Highest shifts are induced for the protons H-10 and H-2 adjacent to the two Lewis base groups of the hormone. Resolution due to induced shift decreases for the other signals with increasing distance of protons from the two coordination sites.

Serum removal from the media of serial monolayer cultures of the Harding-Passey melanoma during an incubation period of 3 days resulted in an exponentially declining DNA synthesis rate (measured by the incorporation of [ 14 C] thymidine) and in an inhibition of cell proliferation. Pro­tein synthesis, as measured by the incorporation of radioactive leucine, was less affected than DNA synthesis. Incubation in serum-free culture medium resulted in significant rises of tyrosinase ac­tivity and cellular melanin content. Addition of dibutyryl adenosine 3′ :5′ monophosphate (Bu 2 cAMP, 5×10 -4 ᴍ) and theophylline (5×10 -4 ᴍ) to serum-free cultures caused a further striking increase of tyrosinase activity and melanin formation, while treatment of serum containing cultures with Bu 2 cAMP and theophylline showed only a slight rise in melanogenesis. It is sug­gested that these stimulatory effects are mediated by an increased intracellular cAMP level, since a correlation between the degree of melanogenesis and cellular cAMP content was indicated. Treat­ment of serum-free or serum-containing cultures with the phosphodiesterase inhibitor theophylline (5×10 -4 - 1×10 -3 ᴍ) alone revealed only a slight enhancement (about 20%) of melanogenesis. Because augmentation of melanogenesis by serum-free medium alone or together with Bu 2 cAMP and theophylline was prevented by cycloheximide (or actinomycin D), de novo protein synthesis seems to be required for these stimulatory effects.

Transmission electron diffraction is used as a qualitative analytical probe of poly methylene chain packing in three conformationally-restricted analogs of tripalmitin derived from configurational isomers of cyclopentane-1,2,3-triol. The analysis demonstrates that the all trans “tuning-fork” conformation seen in X-ray crystal structure analyses on homologous compounds is also found in microcrystals, in contrast to a proposal by Fringeli et al. (Z. Naturforsch. 27 b, 780 [1972]) that an all cis conformation of the triglyceride exists in solvent-grown microcrystals and in multilayers. The presence of mixed polymorphs is also shown for bulk samples previously examined by X-ray powder diffraction techniques by other workers.

The lateral lipid organization and the local surface curvature in small and giant bilayer vesicles of binary lipid mixtures were investigated. Mixtures of the following lipids are studied: Cholesterin, di-alcyl-lecithins, dioleyl-lecithin and di-alcyl-phosphatidic acid. The latter is considered as being representative of charged natural lipids (e.g. phosphatidyl serine or cardiolipin). Three different experimental methods are compared: 1) The excimerfluorescence method, 2) the spin label technique and 3) the freeze fracture electron microscopy. The latter two methods yield information on the size of lipid precipitations. The surface curvature may be studied by electron microscopy. The essential experimental results are: (1) Mixtures of smectic phases of different symmetry undergo lateral phase separation. (2) The phase separation leads to a domain-like lateral lipid organization. (3) The domain structure is often accompanied by a variation in local curvature. (4) In membranes containing a charged lipid component, the domain structure may also be triggered by external charges (such as surface proteins). (5) two types of domains are observed: Circular domains (diameters of the order of several 100 Å) occur in mixtures of non-tilted fluid and rigid phases. Elongated domains (width ∼ 100 Å) are observed in mixtures of tilted and nontilted phases. This domain pattern is characteristic for mixtures of lecithins and cholesterols. The domain structure is explained by combining the theory of spinodal decomposition of alloys with the essential result of the orientational elastic model of membranes. The domain size calculated from this model agrees well with the experimental result. The periodic ripple structure observed between the pre-and the main transition is explained by generalizing the concept of spinodal decomposition to include the separation of phases which are only distinguishable (e. g. by the tilt angle). The width of the domains in equilibrium is explained in terms of the spontaneous curvature of the decoupled monolayer of a bilayer. Good agreement with the experimental result is obtained. The ripple phase is only a special case of the surface induced domain structures in ordinary liquid crystals. The defect structure of the ripple phase has been analysed in terms of its symmetry. A symmetry rule is established which leads to a model of lipid orientation. Below the pretransition no periodic domain pattern is observed under normal conditions. But upon cooling a bilayer very rapidly a defect structure reminiscent of a screw dislocation is ob­ served. This is expected for coupled biaxial monolayers.

The number of antibody molecules which stroma-freed chloroplasts can bind out of the mono-specific antisera to monogalactosyl diglyceride, tri-and digalactosyl diglyceride, sulfoquinovosyl diglyceride, phosphatidyl glycerol, sitosterol, plastoquinone, lutein and neoxanthin was determined. This number was compared to the number of antibody molecules which stroma-freed chloroplasts can maximally bind. The result is that the antibodies to the individual lipids cover at most 17 per cent of the accessible thylakoid membrane surface. From a serum which contains both antibodies to the proteins and lipids of the thylakoid membrane, not more antibody molecules are bound than from a serum to the proteins. This means that antibodies to proteins are able to cover up the entire accessible surface of the thylakoids whereas a mixture of antibodies to the lipids, listed above, cover only one forth of the surface. Consequently, antibodies which are bound to proteins can cover up the lipid areas entirely and in turn antibodies which are bound to lipids cover up parts of the protein areas. From this it follows that the portion of the surface, which is made up by lipids must be considerably smaller than 24 per cent. Furthermore, it follows from these experiments that the lipid areas are small and that lipids probably only fill up the gaps between the protein molecules.

Uncoupling of photophosphorylation was shown in chloroplasts from spinach which were iso­ lated in media containing pyrophosphate and thereafter suspended in salt-free solutions. The effective concentration of pyrophosphate to uncouple was determined by the addition of pyrophos­ phate to free thylakoid systems and shown to be dependent on the presence of the completely dissociated species which favoured complex formation with bivalent cations. Higher concentrations of pyrophosphate led to a stabilization of photophosphorylation. The uncoupling is due to the release of the coupling factor. The degree of liberation was shown to be dependent on the chlorophyll concentration. The capacity of extracted membranes to reconstitute photophosphoryla­tion with their corresponding supernatant or with purified CF 1 was directly correlated to the amount of the liberated coupling factor.

Incubation of class II chloroplasts of spinach with copper in the light at pH = 8 in concentrations that inhibit oxygen evolution results in the formation of a copper (II) protein complex with the photosynthetic membrane. The EPR spectra indicate that the four nearest ligands to Cu(II) consist of three oxygen atoms and one nitrogen atom. The copper (II) protein appears to be pre­ dominantly associated with photosystem II. The formation of this protein as measured by the EPR signal amplitude of its room temperature spectrum correlates with the inhibition of oxygen evolution and of electron transport within photosystem I. This result indicates that the inhibition of photosynthetic electron transport by copper may be due to the formation of a copper (II) chelate with a membrane protein.

Upon illumination, dark starved spinach leaves show a 50% reduction of 14 C-incorporation capacity into lipids. If 32 P-incorporation is measured, the reduction is 85% compared to controls. The relative labelling of the fatty acid residues in total lipids of normal leaves was 80 - 90% compared to 30 - 50% in the darkened material. The kinetics of 14 C-incorporation into lipids show that in the controls the majority of 14 C was located in the monogalactosyl diglyceride fraction while in the dark kept material phosphatidyl glycerol and phosphatidyl choline were more highly labelled. Corresponding with the changed incorporation capacity a decrease in fatty acid concen­ tration in the glycolipid fraction and a simultaneous increase in the phosphatide fraction in dark pretreated leaves is observed. An illumination period of 30 - 60 minutes at 2×10 4 lx brings these inverse values back to normal. The most rapid labelling occurred in a glycolipid fraction lacking galactose and having a slightly more hydrophilic character than monogalactosyl diglyceride. The molar ratio of sugar, glycerol and fatty acids in this fraction is 1 : 1 : 1 - 2. The label in the fatty acid residues of this lipid fraction was approximately 10% in dark kept but 90% in control leaves. From 14 C-incorporation behavior it is suggested that this lipid is a precursor of monogalactosyl diglyceride. The changes of the labelling pattern of lipids in leaves kept in prolonged darkness are similar to those obtained with 3-(3,4-dichlorophenyl) -1,1-dimethylurea treated Chlorella. A close connection of these effects to the decrease of photosynthetic capacity is therefore suspected. Also the observation that the concentration of α-linolenic acid, bound in the glycolipids, is reduced in dark kept material and increases upon subsequent light exposure, fits into this context. A pos­ sible explanation of these labelling shifts seems to be a pH shift in the various cell-compartments induced by light/dark treatment.

Using pH indicator dye techniques we have investigated the pH changes in dark-adapted chloro- plasts following excitation by short flashes. Two types of pH indicator, cresol red and neutral red, were used, to follow the pH changes either inside or outside the thylakoids, or the net change when the membrane was made permeable to protons by uncoupling agents. (1)With cresol red which showed the net pH changes inside and outside the thylakoids, an oscillation of the flash yield of H + occurred with a periodicity of 4 (minima on the first and fifth flashes, the yield on the third being not significantly different from the yields on the second and fourth flashes). The pH changes did not occur in synchrony with O 2 -evolution. (2)The net flash yields without addition of electron acceptor were similar to those with benzyl- viologen. The results were comparable with those obtained with the glass electrode technique by Fowler and Kok (C. F. Fowler and B. Kok, Biochim. Biophys. Acta 357, 299 - 307 [1974]). (3)The net flash yields with ferricyanide as electron acceptor of photosystem I were higher than those in the absence of acceptor, or with benzylviologen. On the first and fifth flashes a net acidification was always observed. (4)In the presence of 3- (3,4-dichlorphenyl) -1,1-dimethylurea (DCMU) a rapid acidification also occured on the first flash, while the pH changes induced by subsequent flashes were inhibited. (5)The uncoupler methylamine did not inhibit the proton uptake outside the thylakoids. (6)With neutral red as indicator for the net pH change inside and outside the thylakoids, the same oscillation of the flash yield occured as with cresol red. (7)With neutral red in the precense of an external buffer, as a pH indicator for the internal aqueous phase alone, an oscillation of the flash yield with a periodicity of 4 also occured. The first and second flash yields were higher compared with the third than the equivalent yields of oxygen. (8)We discuss the results with respect to a model for the release of protons in the water- splitting enzyme reactions, in which protons are not released in synchrony with O 2 , but in the transitions of all the states of the watersplitting enzyme with the exception of S 1 → S 2 . Our results are consistent with this model when account is taken of the release of protons inside the thylakoids with a periodicity of 2, associated with electron transfer from reduced plastoquinone.

Human red blood cell ghosts were prepared by dielectric breakdown of the cell membrane and subsequent electrical haemolysis in isotonic and isoionic solutions. Almost complete removal of haemoglobin (to about 0.1%) could be achieved by subjecting the erythrocytes suspended in isotonic solution to three consecutive electric field pulses of 16 kV/cm in the presence of 10 mᴍ EDTA, followed by dilution with EDTA-free isoionic medium. The cup-shaped ghost cells were electrically homogeneous. The polypeptide composition of the electrically prepared ghost cells, as analyzed by polyacrylamide electrophoresis in 1% SDS, revealed a pattern similar to ghost cells prepared by osmotic haemolysis. However, the band 6, corresponding to glyceraldehyde-3-phosphate-dehydrogenase protomer, was absent from the electrically prepared ghost cells. Also the band 8, which is eluted at low ionic strength, appeared to be very prominent in the electrical preparations.

Dissociation of poliovirus by 9 ᴍ urea in 0.015 ᴍ NaCl at 25 °C resulted in the liberation of 35S RNA and of polypeptides sedimenting at 2S in sucrose gradients containing 9 ᴍ urea. However. a ribonucleopolypeptide (RNPP) complex sedimenting at 45S and oligomers of the viral polypeptides sedimenting at 7 -8S were found in addition to the monomers sedimenting at 2S when the urea concentration was lowered to 5 M after the dissociation procedure. Ribonuclease treatment prevents the appearance of the RNPP-complex. The amount of the RNPP-complex de­ creased, when the dissociation was performed at higher ionic strength. Under these conditions small amounts of empty capsids were detected. Polyacrylamide gel electrophoresis showed that the RNPP-complex contained the polypeptide VP1. The oligomers (7 -8S) contained the polypeptide VP3 and small amounts of VP2. The bulk of VP2 and some VP3 were found in the 2S position together with VP4. The molecular weight of the dissociation products in urea and phosphate buffer was determined by gel filtration to be about 30,000 for the monomeric polypeptides containing predominantly VP2 and about 70,000 for the oligomeric polypeptides containing predominantly VP3. Our results demonstrate that the oligomers and the RNPP-complex are not primary products obtained by dissociation of the virus particle by urea but are due to a reassociation of the poly­ peptides or of VP1 and RNA.

The endocrine system of the honey bee (Apis mellifera L.) has been studied morphologically through post-embryonic development with several histological techniques. Marked differences in the structure of the neurosecretory complex of queen and worker larvae have been observed during larval stages. In queen larvae, morphogenesis of the neurosecretory cells, their axons and the formation of the chiasma takes place during end of 2nd and beginning of 3rd, in the workers at beginning of 4th larval instar. Stainable neurosecretory material was found in queen larvae at the beginning, in worker larvae at the end of 4th instar. In early larval stages, the corpora allata are more active in the queen. During initial 3 - 5 days of larval development the gland volume is reduced in both castes. After 36 to 48 hours of endocrine retardation, the glands become active again. The same histological effects are found under experimental conditions, where worker larvae of 2nd instar were reared in the incubator on basic food, Royal Jelly and with topically applied juvenile hormone I.

The complexation behaviour of Cu(II) with di- and tri­peptides containing the aromatic amino acids phenylalanine or tryptophan has been investigated at different pH-values and compared with results obtained with di- and triglycine. The results obtained by means of ESR and optical absorp­tion spectroscopy show an influence of the two different aromatic entities on the magnetic and optical parameters. A significant decrease of the g ‖ -value and, concomittantly, an increase of the energy of the d-d transition was measured when an aromatic entity is present in the peptide. A possible explanation for this observation is given.

The shape of the barrier for the H transfer between the normal and tautomeric forms have been determined for the adenine and thymine molecules. The correlations for several singlet and triplet states has been calculated using the CNDO/2-Cl method. The relative stability between both conformations and the agreement with some experimental values is also discussed.

In the presence of MnCl 2 and a thiol (glutathione, cysteine, 2-nitro-5-thiobenzoic acid) horse radish peroxidase oxidizes ρ-hydroquinone to ρ-benzoquinone which in turn immediately adds the thiol present yielding 2-S-substituted ρ-hydroquinone.

The antheridiogens (native, antheridia inducing h or­ mones) of both, Anemia phyllitidis (A An 1 and A An 2 ) and Lygodium japonicum (A Ly ), representatives of the Schizae aceae showed similar effects to GA 3 in the dwarf pea bio­ assay.

Testosterone degrading enzymes are synthesized de novo by bacterium P. testosteroni to utilize testosterone-like steroids as the only source of carbon. RNA-synthesis of the whole lysate of testosterone-induced bacteria was found to be 15% reduced compared to the control, suggesting a cytoplasmatic factor which modulates chromatin associated RNA-polymerase activity.

Homogeneous large (5 - 30 μm) lipid particles com­ parable in size and shape to blood cells can be obtained when excess of cholesterol is homogenized with egg phospholipids or brain glycolipids in a Dounce apparatus. The particles contain distinct structures of membranes and lipid cores as visualized by the included fluorescence markers. When these particles were used as models in studying interactions between membranes, it was demonstrated that several properties norm ally pertaining to natural membranes could be exhibited by lipids alone. It could also be shown that particles containing phospholipids or glycolipids were very different in their adhesiveness to tissue culture cells and in their response to sera of various species.

The orientation of microvilli in the compound eye of the butterfly. Pieris protodice, has been examined using electron microscopy. The retinula cells comprising each ommatidium have been divided into four types based upon microvillar orientation, position of nucleus, and location within the om­matidium. The vertical and horizontal retinular types have microvilli in the distal one-third to half of the retina. There is alteration in the orientation of these microvilli of up to 90 . The rhabdom is dominated by the microvilli of the diagonal retinulae in the proximal retina. There is consistant orientation of the diagonal cell microvilli throughout the retina. In mid-retina, these microvilli undergo dramatic alteration in length, leading to a Crustacean-like organiza­tion. for some 50 μm. The basal, or eccentric, retinula cell is bilobed. and has only a few microvilli projecting a short distance into the rhabdom.

The photoreceptor cells of the nymphalid butterfly, Agraulis vanillae, have been structurally characterized. Four distinct types of retinulae can be found in each ommatidium.Two vertically oriented cells contribute microvilli to the to rhabdom only in the distal retina. These microvilli are or-ha]dered into discrete packets. Although the distal-most micro­villi enter the rhabdom in a dorsal-ventral axis, these rhabdomeral packets begin altering their direction of orientation becoming directed at 45° to the vertical alignment of the cells. Abrupt alternations in orientation produce microvillar packets oriented to each other at approximately 90° along the distal portion of each vertical cell. The vertical reti­nulae lose their microvilli at mid-retina and become axonal.Four retinular cells, oriented diagonally across the ommati­dium, contribute microvilli to the rhabdom aligned at 45° to the vertical axis. These diagonal cells produce microvilli throughout the depth of the retina. Two horizontally ordered photoreceptors produce microvilli aligned along a horizontal axis, these cells contributing rhabdomeres along their entire length. A ninth bilobed eccentric cell is arranged in a vertical plane in the basal region of the ommatidium. A few short microvilli are added to the rhabdom from each lobe.These are oriented in a vertical direction.