Volume 29, Issue 1-2

The non methylene interrupted cis,cis-octadecadienoic acids from human milk fat were pre­pared by thin layer chromatography on AgNO 3 impregnated silicagel plates. The position of double bonds was determined by hydroxylation of the double bonds with OsO 4 followed by silylation. The corresponding O-trimethylsilylether derivatives of the fatty acid methyl esters were analyzed by gaschromatography mass spectrometry. 14 isomers of the following series could be identified: C 18:2 ⊿9. (12.13.14.15.16.17) ; C 18:2 ⊿ (6.7.8.9.).12; C 18:2 ⊿ (10.11.12.).15 (⊿18.15) ; C 18:2 ⊿5.9-, ⊿6.10; ⊿10.14; (⊿12.16). Possible biosynthetic pathways are discussed.

The validity of three-component fitting of protein circular dichroism (CD) spectra in the peptide absorption region with basis spectra for helical, β-sheet and unordered structure is examined by matrix rank analysis of protein CD spectra. It is shown that a three-component basis can be justified for several proteins within the limits of experimental error of the spectra. It is suggested that the fitting of protein CD spectra with basis spectra derived from reference proteins should be preceded by matrix rank analysis to show that the CD spectra of the reference and unknown proteins have the same basis.

Radiolysis products resulting from the deamination pathway were isolated and identified after irradiation of cytosine by gamma rays in neutral aqueous solutions. They were identical to those identified in uracil radiolysis i. e. 5,6-dihydroxy-5,6-dihydro-uracil (cis and trans forms), iso-dialuric acid, alloxan, 5-hydroxy-hydantoin, parabanic acid and oxaluric acid. The absence of 4,4′-di-iso-barbituric acid, alloxantin or iso-barbituric acid could be explained by the good stability of uracil glycols. The identification of buiret proof of potential degradation mechanisms different from these involving of the free radical attack on the 5,6 double bond. Gamma Irradiation of Cytosine in an Aerated Aqueous Solution, I

After gamma irradiation of cytosine in aerated aqueous solution, yields of chemical radiation products belonging to the deamination pathway were measured. Primary stable radiolysis products, such as 5,6-dihydroxy-5,6-dihydro-uracil cis and trans forms, were present with G values lower than those obtained in the radiolysis of uracil irradiated under the same conditions. Cytosine had the same radiosensitivity as uracil (G= -2.49).

IR spectra of aqueous solutions of PO 4 3- , ADP 3- , ATP 4- , MgADP - and (MgADP - + PO 4 3- ) (in two cases hydrated layers) were plotted. The parameter for the investigation was the mole percent of protons relative to the anions. The other cations were sodium or potassium. The purpose of our work was to obtain a basis for understanding the results regarding the changes to the interactions in ATP systems on hydrolysis. The addition of protons to the different acceptors is discussed on the basis of the bands of the phosphate groups and of the base ring vibrations. The formation of easily polarizable hydrogen bonds could be demonstrated with the aid of an IR continuum. Such OH + ···O bonds between hydrogen phosphate ions as well as NH +,, -N bonds form in the systems investigated. Thus the conditions for forming such bonds and the resulting intermolecular interactions will become evident in this work.

IR spectra of 0.3 ᴍ aqueous solutions of Mg 0.5 K 3-n HM n ATP were plotted. The dependence of the spectra on the hydrolysis was investigated for three different K/H ratios of the nonhydrolysed system. Changes to bands provide information as to the protons added to the phosphate groups and base residues as a function of the initial protonation and degree of hydrolysis. More and more proton addition to the -PO 3 -- groups is observed as the initial protonation increases and as the degree of hydrolysis rises. The same applies as far as the addition of protons to the base residues is concerned to the systems with a higher initial protonation. At low degrees of hydrolysis the PO 4 3- ions which occur do not bind the two hydrolysis protons completely. 150% protonated PO 4 3- ions first form which cross-like via OH + ···O hydrogen bonds, which only become more strongly protonated in the systems with a higher initial protonation at large degrees of hydrolysis. The OH + ···O bonds between the 150% protonated hydrogen phosphate ions as well as the NH + ···N hydrogen bonds between the base residues cause an IR continuum and are thus easily polarizable. An extremely large change to the hydrate structure within narrow hydrolysis ranges is indicated by changes to the bands of the water molecules. The biological relevance of these findings is briefly discussed in the conclusions.

D 2 O lengthens the free running period of the circadian petal movement of isolated Kalanchoe flowers by 1.6% per 10% heavy water. This corresponds to findings reported in the literature for other organisms. 100% D 2 O administered in the form of 4 hour pulses at various phases of the circadian cycle lead to phase responses zero to maximally 1.5 hour delays. No advancing phase shifts occur. Possible ways in which lengthening of the period occurs are discussed.

Studies in vitro on the binding of phospholipids with IAA, α-NAA and some of their biologically inactive analogues demonstrate that the observed interaction between IA A and lecithin is not related to the primary action of the hormone in plant growth.

[ 35 S]Sodium sulphate was intraperitoneally injected into adult fishes and its incorporation into melanins examined. Relevant incorporation of the tracer into normal skin and peritoneal melano­ cytes of Poecilia reticulata (Peters) and Puntius tetrazona tetrazona (Hamilton) could be detected only in rare cases. Melanocytes of malignant melanomas in the hybrids of Xiphophorus helleri (Heckel) and Platypoecilus maculatus (Guenther) exhibited a different degree of radioactivity ac­ cording to their degree of differentiation. The isolation of the melano-protein complex from melanocytes of these melanomas and its subsequent hydrolysis resulted in the following: During melanin synthesis, [ 35 S] sulphate had been incorporated into the chromophore group as an ester-sulphate, whereas no significant incorporation of the tracer was found in the protein matrix.

Growing yeast cells incorporate radioactivity from labeled nucleotides, deoxynucleotides, deoxyadenosine, and deoxycytidine into acid-insoluble material. Most of these compounds are in­ corporated predominantly into RNA, only dTMP and dTTP serve as effective and selective DNA precursors. When yeast is prelabeled with dTMP, “specific” radioactivity of DNA decreases in the growing cells due to DNA augmentation. In X-irradiated yeast, “specific” radioactivity of DNA again decreases remarkably, though DNA augmentation of the growing giant cells in delayed. Simultaneously, radioactivity is rendered acid-soluble. Vice versa, X-irradiated unlabeled yeast incorporates radioactivity from labeled precursors into DNA, even if the DNA content of the cells does not increase. When growing yeast cells are treated with cycloheximide, protein synthesis and DNA augmen­ tation are inhibited completely with 5·10 -6 ᴍ cycloheximide. The decrease of “specific” radioactivity of DNA in X-irradiated cells, however, proves independent on an intact protein synthesis, even with 1·10 -4 ᴍ cycloheximide. The data provide clear evidence on DNA turnover in growing yeast after X-irradiation.

The [Mg, Ca]-ATPase activity of E. coli depends on the anion present and follows the chaotropic sequence: Acetate - > HCO 3 - > Cl - > I - > NO 3 - > SCN - . There are only small differences between the different alkali chlorides. The [Mg, Ca]-ATPase was inhibited by all these salts when the ratio of Mg or Ca to ATP was 1: 5 at pH 9.1. At pH 9.1 or 7.5 and a Mg to ATP ratio of 1 some salts activate and others inhibit the enzyme according to their position in the chaotropic sequence. With Ca the ATPase was activated under these conditions only by acetate. The contradictory activation or inhibition by NaCl or KCl reported by various authors are due to differences in the Mg: ATP ratios used. The inhibition of ATPase by ethacrynic acid, NEM, pCMB. DCCD and azide is much greater at pH 9.1 than at pH 7.5 and is drastically affected by NaCl or KCl.

The activity of the membrane ATPase of the (Mg, C a)-ATPase-mutant E. coli K 12 strain AN 120 is reduced to about 5 - 50% of the wildtype ATPase. The reduction is greatest at pH 9.1 and a ratio of Mg, or Ca to ATP of 1 :5 , and smallest at pH 7.5 and 9.1 and a ratio of Mg or Ca to ATP of 1 or more.

A Bacillus subtilis mutant (strain 168 try - thy - ) with a thymine-adenine bias in complementary DNA strands was found. After BrU-incorporation into the DNA it was possible to separate physically hybrid DNA-molecules BrU-labeled in different complementary strands using CsCl density gradient centrifugation. These hybrid DNA preparations were used to investigate whether both strands can be informative during transformation. Taking advantage of the selective degradation of BrU-labeled DNA strands by long wavelength UV it was found that the loss of transforming acti vity was the same for both hybrid DNA preparations. Thus indicating that both complementary DNA strands can be genetically active during transformation. These results are supported by trans­ formation experiments with denatured and reannealed DNA-molecules and heteroduplex DNA-molecules.

Long wavelength UV irradiation (302/313 nm) of hybrid and bifilarly labeled BrU-DNA of B. subtilis results in a degradation of the molecular weight of BrU and of parental thymine con­ taining DNA strands. Hydrogen donors present during UV irradiation are able to prevent these “primary” and “secondary” strand breaks. The protection factors are especially large for secondary breaks in parental normal DNA. Through the action of protective agents the biological activity could not be restored. The generation of these primary and secondary strand breaks due to BrU incorporation and the action of hydrogen donors discussed.

Typical C-type oncorna virus particles as shown by electron microscopy have been purified from the supernatant of cultured lymphocytes from bovine leukosis. In the purified C-particle fraction a DNA-polymerase activity was detected. Using several synthetic RNA-or DNA-homopolymers and 70S Friend virus RNA the template response of this bovine leukosis cell particle DNA polymerase was compared with those of feline leukaemia virus DNA polymerase and DNA polymerase from normal bovine lymphocytes. The DNA polymerase detected in the viral preparation of bovine leukosis is suggested to be an oncorna-virus-specific enzyme.

The influence of 4-hydroxy-2,3-/rans-pentenale (HPE) on multiplication of Vaccinia virus in chick fibroblast cultures has been investigated. The cytotoxicity of HPE has been estimated by in ­ corporation of [3H] thymidine, [3H] uridine, [3H] leucine and by morphological tests. The greatest influence of H PE was seen after incorporation of [3H] thymidine. Chick-embryo cultures infected with Vaccinia virus showed a marked increase of DNA synthesis in contrast to the controls. This increase averaged 180% after 16 to 14 hours. HPE 0.05-10_ 3 M caused a reduction of 72% in [3H] thymidine incorporation in virus infected cultures. At the same time virus concentration decreased by 76%. HPE 0.1-10~3 M, a concentration which inhibits the normal cell DNA synthesis by 50%, caused about 90% inhibition in infected cultures; virus m ulti­ plication was 99% inhibited. These findings have been attributed to a selective inhibition of virus DNA synthesis by HPE. and possible mechanisms are discussed.

The chemical cleavage of apomyoglobins by the cyanogen bromide procedure 1 has provided frag­ ments suitable for sequence analysis2, 3 and for studies of physical 4-6 and immunochemical pro­ perties 7 . Offord 8 has used a peptide obtained from the cyanogen bromide cleavage of ribonuclease in studies aimed at the semi-synthesis of a protein. The purpose of this report is to present conditions that reliably separate pure peptide fragments produced from the apomyoglobins of several species. A single gel filtration step obviates the need for additional purification 2,3,6 . The evidence re­ ported here concerns specifically the apoprotein of sperm whale (Physeter catodon) and California sea lion (Zalophus californianus) . The procedure additionally has heen applied 9 without modification to the separation of the cyanogen bromide fragments of apomyoglobin from Amazon River dolphin (lnia geoffrensis), Minke whale (Balaenoptera aeutoro- strala), gray whale (Eschrichtius gibbosus), Dali porpoise (Phocoenoides dalli dalli) and the bottlenosed dolphin (Tursiops truncatus). Cyanogen bromide fragments from two of the variant myoglo­bins which occur to a minor extent in the sperm whale were also separated by this method 10 .

Lateral Inhibition, Compound Eye, Fly Lateral inhibition is a common phenomenon in the eyes of vertebrates as well as of invertebrates. Indications of lateral inhibitory interactions in dipteran eyes have been found by means of electro-physiological techniques*' 2. It was not possible,