Absorption of light by metarhodopsin modifies the effect of a conditioning light on the barnacle photoreceptor

We show that the effect of an adapting light on the sensitivity of barnacle photoreceptors depends on the direction of net pigment transfer [rhodopsin (R) to metarhodopsin (M) or reverse] occasioned by the adapting light. For stimuli giving no net pigment transfer the state of the pigment appears irrelevant, R R having the same effect as M M. With respect to these, R M gives enhanced facilitation and M R depressed facilitation. This suggests a correlation with the prolonged depolarising after-potential (PDA) and the anti-PDA, which follow R M and M R stimuli respectively. These effects appear mainly in less sensitive cells and for higher amounts of conditioning light — but still well within the physiological range and well below the threshold for PDA and anti-PDA induction. The special interest of these results is that they appear to be interpretable only by assuming that absorption of light by metarhodopsin exerts an effect on the stimulus coincident response (LRP), the first demonstration of such an effect.Based on material presented at the European Neurosciences Meeting, Florence, September 1978     

The contribution of pigment transitions to sensitivity changes in the barnacle photoreceptor and the correlation with the prolonged depolarizing afterpotential

A conditioning light can cause a decrease (adaptation) or an increase (facilitation) in the sensitivity of barnacle photoreceptors, as measured by the amplitude of the late receptor potential (LRP). We show that a net transfer of visual pigment from the rhodopsin (R) to the metarhodopsin (M) state induces a large facilitation whereas the reverse transfer results in a much smaller facilitation or even an adaptation. These effects were not due to the response to the conditioning light but to the pigment reactions. When the conditioning light did not alter the pigment population (i.e., M M, R R) it was followed by an intermediate degree of facilitation. These conclusions are correct for cells which have relatively low sensitivity. In sensitive cells, all pigment transitions produce adaptation.LRP facilitation and the prolonged depolarizing afterpotential (PDA) show several common characteristics with respect to pigment transitions: 1.Their magnitude increases with the amount of pigment transferred from R to M. 2. Both are depressed by the M R transition. 3. Their production is impeded by the M R transition. 4. The PDA itself is facilitated by the R M transition and this facilitation decays with a time course comparable to that of LRP facilitation. These results suggest that there may be an underlying process common to LRP facilitation and PDA.     

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

Photostable pigments within the membrane of photoreceptors and their possible role

In the majority of ommatidia of the fly, the membrane of the central rhabdomere contains — besides the rhodopsin — a photostable pigment. Due to its selective absorption in the blue spectral range, this pigment (possibly a carotene) could modify the spectral sensitivity of the central receptor cells. It furthermore may change the fluidity of the microvillus membrane and hence affect the alignment of rhodopsin molecules. Indirect evidence for a possible role of the photostable pigment as an antenna-pigment for rhodopsin is discussed.Presented at the EMBO-Workshop on Transduction Mechanism of Photoreceptors, Jülich, Germany, October 4–8, 1976     

Histochemical studies on the distribution of β-glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of the rat

Summary The present study compares the distribution of -glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of rat. In young cells there are indications of cyclic activity of these enzymes, i.e., in some stages there are perinuclear concentrations of the enzymes, at other times -glucuronidase and succinic dehydrogenase are uniformly distributed throughout the cytoplasm. These stages have been discussed with the identical distribution of mitochondria. However, in old spinal ganglion cells both -glucuronidase and succinic dehydrogenase become mainly concentrated in the pigment areas, suggesting thereby their possible role in the production of pigment, through the medium of the mitochondria.     

Adoptions expérimentales de larves entre des fourmis de genres différents (II):Myrmica laevinodis Nylander etAnergates atratulus Schenck

Résumé Nous avons fait élever des larves d'Anergates atratulus par des ouvrières deMyrmica laevinodis à 22°C. Pour y parvenir, il n'est pas utile de faire hivernerensemble les larves d'Anergates et les ouvrières deMyrmica. La présence de larves autochtones n'empêche pas lesMyrmica d'élever des larves d'Anergates. Dans toutes les expériences lesMyrmica ont été soumises au fridavant de recevoir des larves d'Anergates. Aucune reine deMyrmica n'a été utilisée dans ces expériences.Sur les 64 larves d'Anergates que nous avons utilisées, 38 se sont transformées en imagos. C'est au début de l'adoption et au moment des métamorphoses que périrent la plupart des 26Anergates perdus. Les femelles vécurent en général 2 ou 3 jours et cherchèrent très tôt à quitter le nid natal. Les mâles vécurent 2 à 3 semaines.

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Summary Larvae ofAnergates atratulus were experimentally reared by workers ofMyrmica laevinodis, at 22°C. An overwintering of both larvae ofAnergates and workers ofMyrmica is not necessary for the success of that experiment. The presence of larvae ofMyrmica does not keep theMyrmica from rearing larvae ofAnergates. The workers ofMyrmica have been cooled, in all the experiments, before receiving larvae ofAnergates. No queen ofMyrmica have been used in that experiments.38 of the 64 larvae ofAnergates used became imagos. Most of the 26 lostAnergates died at the beginning of the adoption and during the metamorphosis. The females lived generally 2 or 3 days and tried, very early, to leave their native nest. The males lived 2 or 3 weeks.

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Anergates atratulus Myrmica laevinodis, 22 . bmecme Anergates Myrmica. Myrmica Anergates. Myrmica Anergates. Myrmica . 64 Anergates , 38 . 26 Anergates 2 3 . 2 3 .

     

Correction of the published sequence for the human proteolipid protein gene

Summary In the human proteolipid protein gene, the base sequence of the intronic region 5 to exon 6 was found to be 5-ctctttcattttcctgcag-3 and not 5-ctctttt-cattttcctgcag-3 as previously reported.     

Central-Cis isomers of lutein found in the major light-harvesting complex of Photosystem II (LHC IIb) of higher plants

Lutein (,-carotene-3,3-diol) is the major carotenoid of the light-harvesting systems of higher plants. Lutein was isolated at 4°C and in complete darkness from the bulk light-harvesting complex of Photosystem II of spinach (LHC IIb) and from BBY particles. Separation using normal-phase HPLC (with 2D detection) in comparison to the authentic isomers (prepared by iodine-sensitised isomerization) showed the presence of a number of geometrical isomers of this xanthophyll in PS II, namely all-trans (the major component); 13-cis, 13-cis and 15-cis-lutein. Iodine-sensitised photo-isomerization of all-trans lutein produced six geometrical isomers of lutein as determined by HPLC. The configuration of five of these isomers was determined by ¹H-NMR to be all-trans, 9-cis, 9-cis, 13-cis and 13-cis. In addition, small amounts of another isomer have been tentatively identified to be 15-cis lutein on the basis of its electronic absorption spectrum. The possible functional significance of the presence of cis-isomers of this carotenoid in LHC IIb is discussed.     

Regulation of guanylate cyclase activity by atrial natriuretic factor and protein kinase C

Summary The putative second messenger of certain atrial natriuretic factor (ANF) signal transductions is cyclic GMP. Recently, we purified a 180-kDa protein, apparently containing both ANF receptor and guanylate cyclase activities, and hypothesized that this is one of the cyclic GMP transmembrane signal transducers. The enzyme is ubiquitous and appears to be conserved. Utilizing the 180-kDa membrane guanylate cyclase, we now show that the 180-kDa guanylate cyclase is regulated in opposing fashions by two receptor signals—ANF stimulating it and protein kinase C inhibiting it. Furthermore, protein kinase C phosphorylates the 180-kDa enzyme. This suggests a novel switch on and switch off mechanism of the cyclic GMP signal transduction. Switch off represents the phosphorylation while switch on the dephosphorylation of the enzyme.     

Evaluation of an exotic maize population adapted to a locality

Summary An exotic Zea mays L. population (Tuxpeno) was adapted to North Carolina conditions by first introducing genes for adaptability from two North Carolina varieties ([(Jarvis X Indian Chief)Tuxpeno]Tuxpeno) including four generations of intermating, and then selecting for adaptability using maturity as the primary measure. The study evaluated selection for adaptability and the diversity available between adapted Tuxpeno and the local varieties, Jarvis and Indian Chief. Analytical procedures were developed to quantify the diversity between populations and the complementation of local varieties by introduced germ plasms. The analyses utilized the specific effects available from the diallel mating design.Three replicate selections responded similarly under simple recurrent mass selection (1/10) for the earliest disease-free plants initially and additionally for plant types (primarily height) in the final generation. The 1/4 local germ plasm permitted rapid adaptation of Tuxpeno gene pool to local conditions. The adapted Tuxpeno populations yielded similarly to the local populations with an average heterosis for grain yield of 28% when crossed to the local populations used as source of genes for adaptability. The diversity found between adapted Tuxpeno lines and these local varieties based on genes affecting grain yield was 1.5 to 2.5 times that measured between the local varieties (Jarvis and Indian Chief). Diversity lost through intergradation with local material was a reasonable investment. Yield genes introduced from Tuxpeno complemented local gene pools through nonadditive, primarily dominance-associated, gene effects. Reassortment of major gene blocks apparently occurred leading to significant divergence among replicate selections involving both additive-associated and dominance-associated gene effects.Paper No. 6355 of the North Carolina Agri. Res. Ser., Raleigh, NC. Research supported in collaboration with the Rockefeller Foundation and CIMMYT, D.F. (Mexico)     

Residual motion of hemoglobin-bound spin labels and protein dynamics: viscosity dependence of the rotational correlation times

The residual motion of spin labels bound to cysteine 93 and to lysines of methemoglobin has been studied by electron paramagnetic resonance spectroscopy. To separate the influences of the solvent and the protein environment of the label fluctuations, the correlation times, , were analyzed as a function of temperature for fixed solvent viscosities, . Results show that over a wide range of viscosity the dependence of on may be empirically described by a power law ^k . The exponent k depends strongly on the location of the label on the protein surface. If one regards the spin labels as artificial amino acid side chains, characteristic values of correlation times and amplitudes of the rotational motion at the surface can be given. For =1 cP and T=297 K the correlation time of the labels bound to lysines is found to be =9 · 10^–10 s and the rotational diffusion is nearly isotropic. The spin label bound to cysteine 93 occupies a protein pocket, its rotational motion is therefore restricted. The correlation time of the label motion within a limited motion cone of semi angle =30° ± 3° is found to be =1.3 · 10^–9 s for =1 cP and T=297 K.     

A structural model for elongation factor 1 (EF-1) and phosphorylation by protein kinase CKII

EF-1a binds aminoacyl-tRNA to the ribosome with the hydrolysis of GTP; the complex facilitates the exchange of GDP for GTP to initiate another round of elongation. To examine the subunit structure of EF-1 and phosphorylation by protein kinase CKII, recombinant , , and subunits from rabbit were expressed in E. coli and the subunits were reconstituted into partial and complete complexes and analyzed by gel filtration. To determine the availability of the and subunits for phosphorylation by CKII, the subunits and the reconstituted complexes were examined as substrates for CKII. Formation of the nucleotide exchange complex increased the rate of phosphorylation of the subunit and reduced the Km, while addition of to or the complex inhibited phosphorylation by CKII. However, a had little effect on phosphorylation of . Thus, the and subunits in EF-1 were differentially phosphorylated by CKII, in that phosphorylation of was altered by association with other subunits, while the site on was always available for phosphorylation by CKII. From the availability of the subunits for phosphorylation by CKII and the composition of the reconstituted partial and complete complexes, a model for the subunit structure of EF-1 consisting of (22)2 is proposed and discussed.     

Observations on the fine structure of the cercaria of Notocotylus attenuatus and formation of the cyst wall of the metacercaria

Summary The dorsal tegument of the mature cercaria of Notocotylus attenuatus is a syncytial, cytoplasmic layer, containing two types of secretory granule which are identifiable ultrastructurally. The type 1 secretory bodies are electron lucid, whereas most type 2 granules have a banded appearance. The ventral tegument contains granules which are secreted from the type 3 cells; the type 3 granules are membrane bound, electron dense, and consist of both an amorphous and a finely striated zone. The type 4 cells mainly contain cigar-shaped granules consisting of an amorphous core surrounded by concentric striations. The granules exhibit structural variability in shape and content. The type 4 cells undergo a cellular migration to the tegument during encystment. The structure of the posterior-lateral glands and mode of secretion of the granules are described. Possible functions of microtubules are discussed for each cell type. Details of some secretory processes involved in the formation of the hemispherical cyst wall are described. The layers of the cyst wall may be related to the granular contents of the various parenchymal cells of the cercaria. The tegument of the metacercaria originates primarily from the cytoplasm of the type 1, type 2, type 3 and type 4 cells.     

Sialidase of swine influenza A viruses: variation of the recognition specificities for sialyl linkages and for the molecular species of sialic acid with the year of isolation

The sialidase of swine influenza A viruses of N1 and N2 subtypes, isolated from 1930 to 1992, was studied for substrate specificity with ganglio-series, lacto-series type II and GM3 gangliosides containing Neu5Ac2-3Gal, Neu5Gc2-3Gal and Neu5Ac2-6Gal linkages. All viral sialidases tested showed that the activity for hydrolysing substrates with Neu5Ac2-3Gal was higher than the activities with Neu5Gc2-3Gal and Neu5Ac2-6Gal linkages. When GM1b, GM3 and sialylparagloboside were used as substrates, the earliest strain (A/Wisconsin/15/30 H1N1, isolated in 1930) showed the activity ratio of Neu5Ac2-6Gal to Neu5Ac2-3Gal to be 0.13:0.2, and the ratio Neu5Gc2-3Gal/Neu5Ac2-3Gal to be 0.19:0.37, while those strains isolated from 1978 to 1992 exhibited ratios of 0.29:0.58 for Neu5Ac2-6Gal/Neu5Ac2-3Gal and 0.51:0.76 for Neu5Gc2-3Gal/Neu5Ac2-3Gal. The above results indicate that the substrate specificities of sialidases from swine influenza A viruses towards sialyl linkages and the molecular species of sialic acid are related to the year of isolation, i.e. strains isolated after 1978 exhibited higher activity towards Neu5Ac2-6Gal and Neu5Gc2-3Gal linkages when compared with strains isolated in an earlier year, 1930.Abbreviation Neu5Ac 5-N-acetylneuraminic acid - Neu5Gc 5-N-glycolyneuraminic acid - Gal d-galactose - Glc d-glucose - Cer Ceramide - II³(Neu5Ac)Lac Neu5Ac2-3Gal1-4Glc - GM3(Neu5Ac2-3Gal) Neu5Ac2-3Gal1-4Glc1-Cer - GM3(Neu5Gc2-3Gal) Neu5Gc2-3Gal1-4Glc1-Cer - GM1b(Neu5Ac2-3Gal) Neu5Ac2-3Gal1-3GalNac1-4Gal1-4Glc1-Cer - GMlb(Neu5Gc2-3Gal) Neu5Gc2-3Gal1-3GalNAc1-4Gal1-4Glc1-Cer - IV³(Neu5Ac)nLc4Cer Neu5Ac2-3Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - IV³(Neu5Gc)nLc4Cer Neu5Gc2-3Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - IV⁶(Neu5Ac)nLc4Cer Neu5Ac2-6Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - TDC taurodeoxycholate.     

Synthesis of Gal-β-(1→4)-GlcNAc-β-(1→6)-[Gal-β- (1→3)]-GalNAc-α-OBn oligosaccharides bearing O-methyl or O-sulfo groups at C-3 of the Gal residue: specific acceptors for Gal: 3-O-sulfotransferases

Our recent studies have revealed the existence of two distinct Gal: 3-O-sulfotransferases capable of acting on the C-3 position of galactose in a Core 2 branched structure, e.g., Gal14GlcNAc16(Gal13)GalNac1OBenzyl as acceptor to give 3-O-sulfoGal14GlcNAc13(Gal13)GalNAc1OB 20 and Gal14GlcNAc16(3-O-sulfoGal13)GalNAc1OB 23. We herein report the synthesis of these two compounds and also that of other modified analogs that are highly specific acceptors for the two sulfotransferases. Appropriately protected 1-thio-glycosides 7, 8, and 10 were employed as glycosyl donors for the synthesis of our target compounds.     

Immunofluorescence localization of the epidermolytic toxin target in mouse epidermal cells and tissue

Summary An epidermolytic toxin target was observed in keratohyalin granules of sectioned epidermis by a direct fluorescence procedure using FTC-toxin, but not by an indirect procedure using sequential reaction with toxin, anti-toxin and FTC-secondary antibody. The investigation of the two procedures was extended to keratinocytes. A dispase digestion procedure yielded three fractions which corresponded to basal, spinous and granular cells according to biochemical and morphological criteria. It was shown that the direct and indirect procedures both detected the toxin target in the keratohyalin granules of granular cells, but that the indirect procedure was very insensitive. In control experiments, the profilaggrin of keratohyalin granules was detected readily in cells by a direct procedure using FTC-antiprofilaggrin but only weakly by an indirect double antibody procedure. Insensitivity to indirect procedures thus appears to be a particular property of the keratohyalin granule site. It was shown that the toxin target was readily accessible in permeable (trypsin-isolated) granular cells but inaccessible in impermeable (dispase-isolated) cells.     

Rhodopsin phosphorylation occurs at metarhodopsin II level

Photolyzed rhodopsin was phosphorylated in bovine rod outer segments incubated at –10 C. In the experiment in which urea-treated outer segments and rhodopsin kinase were incubated with ATP in the presence of 30% glycerol, the extent of phosphate incorporation at –10 C was about 30% of that at 37 C. Separation of phosphorylated rhodopsin by isoelectric focusing indicated that a limited number of sites were phosphorylated at –10 C. The partially phosphorylated pigment incorporated more phosphates when the temperatures was raised to 37 C. This was partly due to decreased inhibition of phosphorylation by glycerol at higher temperature. Since the maximum phosphorylation at –10 C (at which metarhodopsin II is stable) occurred at a pH value (6.0) lower than the pKa for metarhodopsin I-metarhodopsin II transition, metarhodopsin II was suggested to be the preferred substrate for rhodopsin kinase at –10 C. Limited proteolysis with thermolysin of rhodopsin phosphorylated at 37 C released peptides containing about 50% of the total phosphate incorporated. In contrast, proteolytic digestion of rhodopsin phosphorylated at –10 C released negligible amounts of phosphate-containing peptides. The results were taken to suggest that the incorporation of phosphates at metarhodopsin II level under the present condition occurred in the residues other than those removed by thermolysin digestion.Based on material presented at the Fifth International Congress of Eye Research, Eindhoven, October 1982     

Structural studies of the glycopeptides of B-chain of cinnamomin – a type II ribosome-inactivating protein by nuclear magnetic resonance

Cinnamomin is a plant type II ribosome-inactivating protein (RIP) isolated from the seeds of Cinnamomum camphora. It consists of two nonidentical polypeptide chains (A- and B-chain) held together through one disulfide linkage. Its A- and B-chain contain 0.3% and 3.9% sugars respectively. The B-chain of cinnamomin was digested by pronase E and then the liberated glycopeptides were separated from non-glycopeptides by gel filtration chromatography on a Bio-Gel P-4 column. Three crude glycopeptides were obtained by continuing chromatography over anion-exchange resin (AG1-X2) in the buffer of 2% pyridine-acetic acid (pH 8.3) with a polygradient elution system. Through further purification by the gel filtration chromatography and HPLC, three major glycopeptides, GP1, GP2 and GP3 were obtained. Mainly by two-dimensional Nuclear Magnetic Resonance (NMR) including TOCSY, DQF-COSY, NOESY, HMQC and HMBC, their primary structures were analyzed as: Man1,3Man1,6(Man1,3)(Xyl1,2)Man1,4GlcNAc1,4GlcNAc1-(Gly-)Asn-Asn-Thr(GP1), Man1,6(Man1,3)(Xyl1,2)Man1,4GlcNAc1,4(Fuc1,3)GlcNAc1-Asn-Ala-Thr(GP2),Man1,6(Man1,3)Man1,6(Man1,2 Man1,3)Man1,4GlcNAc1,4GlcNAc1-(Ala-)Asn-Gly-Thr(GP3).     

Intracellular sites of the synthesis of sweet potato mitochondrial F1ATPase subunits

Summary Five subunits (-, -, -, - and -subunits) of the six -and -subunits) in the F₁ portion (F₁ATPase) of sweet potato (Ipomoea batatas) mitochondrial adenosine triphosphatase were isolated by an electrophoretic method. The - and -subunits were not distinguishable immunologically but showed completely different tryptic peptide maps, indicating that they were different molecular species. In vitro protein synthesis with isolated sweet potato root mitochondria produced only the -subunit when analyzed with anti-sweet potato F₁ATPase antibody reacting with all the subunits except the -subunit. Sweet potato root poly(A)⁺RNA directed the synthesis of six polypeptides which were immunoprecipitated by the antibody: two of them immunologically related to the -subunit and the others to the - and -subunits. We conclude that the -subunit of the F₁ATPase is synthesized only in the mitochondria and the -, - and -subunits are in the cytoplasm.