Volume 28, Issue 3-4

The aspects of molecular-structure and biological conversion have been studied for 12 derivatives of the endosulfan ether 1 [4, 5, 6, 7, 8, 8- hexachloro- 1, 3, 3a, 4, 7, 7a- hexahydro- 4, 7-methanoisobenzofuran]. Adults of a normal house-fly strain (Musca domestica) have been used in the assay. Derivatives of 1 monosubstituted in position I are found to be converted substantially faster than products disubstituted in position I and 3, respectively. Metabolism is inhibited for all compounds studied after application of piperonyl butoxide as a synergist. Besides proving that on oxidative metabolism has to be discussed and in fact could be proved for some derivatives, the intrinsic toxicity of the compounds studied shows up under these conditions. Some derivatives known to be metabolites of the pesticide Endosulfan ® show a high intrinsic toxicity to houseflies if the oxidative metabolism is inhibited.

The incorporation of [G- 3 H]-dihydrokaempferol into catechins o young tea shoots Camellia sinensis L.) was compared with that of ʟ-[U- 14 C]-phenylalanine and [U- 14 C]-shikimic acid. The percent incorporation of all three precursors into (-)epicatechin was about equal, whereas the incorporation of shikimic acid into the galloylated catechins was somewhat higher than that of phenylalanine and dihydrokaempferol. From the results it can be concluded that dihydro­ kaempferol is a precursor for catechins in the tea plant.

The condensation of racemic lysine to poly-ᴅʟ-lysine produces a great number of distinguishable molecules. Following merely statistical reasoning the number of “pure peptides“ - consisting of only one sort of enantiomers - should be extremely low. The hydrolysis of poly-ᴅʟ-lysine by pronase and taka-diastase shows that a content of about 3% “pure“ poly-peptide is found in the product, which emphasises the preferential sythesis of identical enantiomers within the polymer diain.

Purified isolated spinach chloroplasts were suspended in media of different pH and the extracts obtained after centrifugation were analyzed for their lipid composition. The quantity of lipids present in the supernatant increased considerably by lowering the proton concentration. Under alkaline conditions more than 30% of the phospho- and sulfolipids were released from the thylakoid membranes. A stabilization was achieved when higher concentrations of MgCl 2 were present. Photochemical activities showed an uncoupling of photophosphorylation at pH 8.5 and 8.9, and a stabilization at pH 5.5. The correlation between phosphorylation and the release of lipids was further demonstrated in the presence of MgCl 2 when the ATP-formation was protected under alkaline conditions. From the comparison of the lipid composition in the extracts obtained from broken chloroplasts and from fragments after sonication, the conclusion can be drawn that part of the phospho- and sulfolipids and monogalactolipids are located at the surface of the membrane. The majority of lipids released are bound to particles as demonstrated by the sedimentation in the ultracentrifuge.

With reference spectra derived from proteins of known structure (CHEN, YANG, and MARTINEZ, Biochemistry 11, 4120 [1972]) a better approximation of the circular dichroism spectrum of fragments of the thylakoid membrane is achieved, than by the use of polylysine as reference substance. Most probably the protein in the thylakoid membrane consists of 40 per cent helix, 42 per cent random coil and 18 per cent β-structure.

To observe the influence of substances on specific enzymes of the semiconservative DNA- synthesis and DNA-repair replication a screening system was developed, which represents an extensive modification of known papers. Optimal conditions were found after comprehensive investigations. The detergens Tween 80 and the antileukemic drug cis-platinum(II)diammino- dichloride were used as test substances.

Proton and Deuteron spin - lattice relaxation have been measured in aqueous solutions of herring sperm DNA as a function of concentration, temperature, and NMR frequency. We find a minimum if the increment of the relaxation rates, 1/T 1 -1/T 1 (free solvent) is plotted as a function of the inverse temperature. The result can be understood by assuming a superposition of two exchange processes: a very rapid exchange of water molecules causes the rate increment at lower temperatures whereas the frequency dependent rate increment in the high temperature region is caused by slow exchange of bound water molecules or DNA protons. The correlation time or the exchange time of the fast exchanging water molecules is smaller than 10 -9 s at 4 0 C with an activation energy of 7.2 kcal/mole, whereas the slowly exchanging water molecules or DNA protons have at the same temperature a correlation time of more than 10 -7 s with an activation energy of 9,8 kcal/mole and an exchange time of 1 s with an activation energy of 11.5 kcal/mole.

A single beam, single reflectance photometer for investigation of monolayers at the air water interface is described. A cyanine dye monolayer is studied. The molecular arrangements in different monolayer states are derived from the observation o f the monomer-dimer equilibrium of the dye chromophores.

The effect of three drugs on the receptor potential (ReP) of the crayfish retina measured with external electrodes was tested. 1. Tetrodotoxin (TTX) (1·10 -6 g/ml and 1·10 -5 g/ml) showed only slight effects on the receptor potential (Table I and II). 2. Veratridine (VERA) (1·10 -5 g/ml) showed only small effects of the same type as TTX but a little stronger on the receptor potential which became obvious especially in the period after washing out the drug (Table III). 3. Tetraethylammonium (TEA) (5 mм/1) caused a decrease of the height of the receptor potential without influencing the repolarizing phase (decrease-time £2) markedly (Table IV). The results can be interpreted as follows: 1. The permeability increase for sodium, calcium and magnesium, whidi causes the rising phase of the receptor potential in the crayfish photoreceptor cell is of different nature than the increase of the sodium permeability in the squid nerve, or the sites of the sodium channel are not accessible for the TTX in the photoreceptor cell. This is shown by the experiments with TTX and VERA. 2. AU the changes of the receptor potential which are caused by TEA can be explained by assuming that the permeability for potassium in the dark is lowered by TEA and that in the course of the normal receptor potential an increase of potassium permeability, which causes the decreasing repolarizing phase of the receptor potential, does not occur.

Monomolecular films of 9-cis, 11-cis, 13-cis and all-trans retinal were formed at an air-water interface. Area/molecule and surface potential were measured before, during and after illumination. The initial quantum yield of the photoisomerization of 9-cis retinal was 0.25. Irradiation of a retinal monolayer resulted in 30 to 60 mVolt changes in surface potential. Complexation of retinals with lysine and cysteine were studied.

The comparsion of the experimental UV-spectra of 3,4-BP and 1,2-BP requires a possible coupling of pure a~ and p-states for 3,4-BP through an asymmetric potential in the order of thermal energy. The former postulated resonance hypothesis of carcinogenesis is supported with the obvious assumption that the energy change of a- and of the carcinogen with the bioreceptor.

A method is described of mixing solutions in a cartesian submicroliter-diver with a gas volume of about 0.2 μl. The solutions are mixed within about 10 sec. Approximately 1-2 min after interruption of the experiments the readings are resumed.

In vivo tests give evidence that the epidermis is the target organ for the juvenile hormone of insects. A study of the distribution of injected 10,11-epoxy-6,7-trans-2,5-trawi-farnesyl-propenylether and of its metabolic products in epidermis, lymphae, and other organs demonstrated that the unaltered ether accumulates in the epidermis against a concentration gradient and is more slowly metabolised there than in the non-target organs.

Two protein fragments with a molecular weight of 50-60 000 daltons are formed when the calcium transport ATPase of the SR is mildly digested with trypsin. The initial fragmentation of the ATPase does not interfere with calcium transport, calcium dependent ATPase activity and phosphoprotein formation. The decay of the initially formed protein fragments after prolonged tryptic digestion is accompanied by the decline of the rate of calcium uptake and the calcium concentrating ability while the activity of the calcium activated ATPase is reduced only moderately. The initial tryptic fragmentation does not give rise to any change in the morphological appearance in the SR membranes. After prolonged digestion brush border or smooth surface structures are observed depending on the agent used for negative staining.

The cytoplasm of growing HeLa cells contains a certain quantity of native ribosomal subunits. They constitute a heterogeneous fraction consisting of at least two categories of particles. The first category comprises the newly emerging native 40S subunits which do not form 80S couples under any in vitro condition tried. It is postulated that these native subunits carry an anti-association factor which cannot be stripped off by 0.5 м KCl treatment. Transiently native subunits of the second category reassociate to 80S ribsomes only in the presence of an association factor.

Embryonic rat fibroblasts were accumulated in G 1 -phase by incubation in serum-free medium and subsequently stimulated by the addition of calf serum. Using 3 H-inositol and 14 C-choline as label for phospholipids, the following results have been obtained: 1. Within a few minutes after stimulation up to 20 per cent of total phosphatidyl 3 H-inositol is released from the membranes of prelabelled cells. This could not be detected with 14 C-choline- prelabelled phospholipids. 2. Incorporation of 3 H-inositol into phosphatidyl inositol, but not the uptake into the acid-soluble cell pool, is increased 30 and 45 min after stimulation by a factor of 2.8 and 3.3 respectively. Incorporation of 14 C-choline at that time is significantly lower (2.0 and 1.6 respectively). 3. Incorporation of 32 P inorganic phosphate into the lipid fraction of stimulated cells is 8.9 times higher after 10 min as compared with the controls.

ATP-cleavage on the surface of L-5222 leukaemic cells of the BD IX-rat occurs at a rate of only 20% of the corresponding value for normal leucocytes.

Bacterial cell walls are concerned with the tumor induction by Agrobacterium tumefaciens on leaves of Kalanchoe in two different ways: 1. If an inoculum of the virulent strain B6 of A. tumefaciens is mixed with cells of the avirulent strain IIBNV6 or with high concentrations of cell wall preparations from B6 itself tumor induction is inhibited. The same is true with cell wall preparations which were treated with ether or chloroform. In vitro growth of the bacteria is not influenced by cell wall preparations. 2. Penicillin inhibits tumor induction by inhibiting bacterial growth. Addition of penicillin as late as 8 hours after infection is still inhibiting tumor initiation. Growth of induced tumors is not inihited by penicillin. The meaning of the two cell wall related processes in tumor induction is discussed.

The enzyme-template complex of influenza RNA polymerase (fowl plague virus) was purified 200-fold. The sole virus component found in this preparation was RNP-antigen. All attempts to remove the internal template led to an irreversible loss of enzyme activity. The complex was essentially free of nucleases. It synthesized exclusively viral minus strand RNA and was unable to initiate more than one cycle of RNA synthesis. The lag phase at the beginning of RNA synthesis in vitro, present in crude enzyme preparations, was abolished with the purified complex. The enzyme was sensitive to sulfhydryl reagents and it was able to accept α-S-ATP in place of ATP.

While the enzyme template complex of fowl plague virus (FPV) polymerase is rather stable during incubation in vitro, some of the newly synthesized RNA is degraded rapidly. At low temperatures a pronounced lag phase of RNA synthesis occurs, which can be prevented by incubation with substrate. The in vitro products are initially single-stranded RNA, which are converted to partially double-stranded molecules by phenol and SDS. The results are compatible with an open replicative intermediate structure, in which the newly synthesized RNA is bound to the complementary template only over a rather short region at the growing point. A comparison of the temperature characteristics of the RNA polymerases of the highly virulent FPV with that of the low pathogenic virus N revealed that the lag phase is a virusspecific property. There appears to exist a correlation between virulence and heat stability of this enzyme, the activity of which is rate limiting at the normal temperature of the host (41 °C).

In C-type particles of mammalian origin, two different antigenic determinants of the interspecies type have been revealed by a comparative study of murine-, feline-, suidian-, simian (woolly monkey) (SSV-1)-and RD 114 -viruses. With respect to the distribution of interspecies determinants, these viruses can be arranged into two distinct groups; one comprises the rodent- and cat-, the other the pig- and monkey-viruses. RD 114 -virus appears to share a certain non-interspecies antigenic component with cat viruses (strains Rickard and Gardner) but behaves, as far as its interspecies antigenic determinant is concerned, more similar to pig- and woolly monkey-viruses. In showing the serological differences mentioned, IgG antibody could replace whole serum.