Light saturation curves and quantum yields in reaction centers from photosynthetic bacteria.

Reaction centers isolated from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 mutant were irradiated with laser pulses of variable energy and the amount of photooxidation of the primary electron donor bacteriochlorophyll was measured. The resultant light saturation curve fits an exponential function and not a hyperbolic or hyperbolic tangent function. Analysis using either a Poisson statistical model or a simple kinetic model predicts an exponential light saturation curve in the limit where the light pulse is long relative to any transient intermediate states. The absolute quantum yield of photochemistry was found to be 0.98, utilizing the entire light saturation curve. Distortions from the simple exponential light saturation behavior are predicted when very short laser pulses are used.     

Differences in Ca2+ mobilization induced by alpha-adrenergic agonist and phosphatidic acid in cultured hepatocytes

In an attempt to elucidate the relationship between phosphatidylinositol breakdown and alpha-adrenergic responses, effects of phosphatidic acid and phosphatidylinositol related metabolites on Ca²⁺ mobilization and glucose output in cultured hepatocytes were examined. Norepinephrine induced the net ⁴⁵Ca²⁺ efflux from preloaded cells and stimulated glucose output via alpha-adrenergic receptor stimulation, whereas phosphatidic acid caused ⁴⁵Ca²⁺ uptake to cells and did not stimulate glucose output. Myo-inositol-monophosphate, diglyceride and arachidonic acid, which are released by phosphatidylinositol breakdown, had no effect on ⁴⁵Ca²⁺ efflux and glucose output in cells. These results suggest that phosphatidic acid and phosphatidylinositol related metabolites can not mimic the alpha-adrenergic actions in cultured hepatocytes.     

Structure of defective DNA molecules in Epstein-Barr virus preparations from P3HR-1 cells.

Epstein-Barr virus (EBV), isolated from P3HR-1 cells, induces early antigen and viral capsid antigen upon infection of human B-lymphoblasts. The strong early antigen- and viral capsid antigen-inducing activity is only observed in P3HR-1 virus preparations harboring particles with defective genomes, suggesting that this biological activity is directly associated with the defective DNA population. After infection of EBV genome-carrying Raji or EBV genome-negative BJAB cells, defective genomes of P3HR-1 EBV DNA are replicated in excess, depending on the multiplicity of infecting EBV particles. Hybridization of the DNA from such infected cells with 32P-labeled EBV DNA after HindIII cleavage reveals six hypermolar fragments. Mapping of these fragments shows that they form one defective genome unit containing four nonadjacent regions (alpha, beta, gamma, and delta) of the nondefective P3HR-1 EBV DNA. Two of the segments (alpha and beta) contain ca. 17 and 13 megadaltons, respectively, from the terminal regions of the P3HR-1 genome, whereas the two smaller segments (gamma and delta) contain ca. 3.7 and 3.0 megadaltons, respectively, originating from the central portion of the genome. In the defective molecule, the regions gamma and delta are present in the opposite orientation compared with nondefective P3HR-1 EBV DNA. Tandem concatemers are formed by fusion of the alpha and beta regions. Our model suggests that tandem concatemers of three defective genome units can be packaged into virions in P3HR-1 cells.     

Characterization of newly isolated monoclonal antibodies against MHC of a Japanese wild mouse

We have already developed nine B10.MOL congenic strains carrying H-2 haplotypes derived from Japanese wild mice, Mus musculus molossinus, with the C57BL/10 genetic background. To obtain monoclonal antibodies against the H-2 antigen of the Japanese wild mouse, we carried out cell fusion using spleen cells from the animal immunized with one of the B10.MOL strains, B10.MOL-SGR (H-2 ^wm7). As a result, 19 hybridomas producing monoclonal antibodies were produced. Analysis with the intro-H-2 recombinants derived from B10.MOL-SGR indicated that 8 of them reacted with the class I and II with the class II molecule. The class I antibodies were tested for their cross -reactivities on wild mice and on the panels of standard inbred and B10.MOL strains. Most of the antibodies reacted with both the Japanese wild mice and the other subspecies, including standard inbred, while two antibodies highly specific for the donor H-2K region reacted with only three wild-derived mice, two M. m. molossinus from Anj o and Shizuoka, Japan, and one M. m. domesticus from Pigeon, Canada. In addition, all of the other four antibodies reactive with the K antigen of B10.MOL-SGR also reacted with the same three wild mice. The wild mice belonging to different subspecies might share very similar H-2K antigenic determinants in spite of their genetic and geographical remoteness.     

Effect of gamma-ray irradiation on alcohol production from corn

Cracked corn was irradiated with gamma rays at 0-100 Mrad and the effects of the irradiation on sugar yield, susceptibility to enzymatic hydrolysis of starch, yeast growth, and alcohol production were studied. Gamma irradiation at 50 Mrad or greater produced a considerable amount of reducing sugar but little glucose. At lower dosages, gamma irradiation significantly increased the susceptibility of corn starch to enzymatic hydrolysis, but dosages of 50 Mrad or greater decomposed the starch molecules as indicated by the reduction in iodine uptake. About 12.5% reducing sugar was produced by amylase treatment of uncooked, irradiated corn. This amount exceeded the level of sugar produced from cooked (gelatinized) corn by the same enzyme treatment. The yeast numbers in submerged cultivation were lower on a corn substrate that was irradiated at 50 Mrad or greater compared to that on an unirradiated control. About the same level of alcohol was produced on uncooked, irradiated (10(5)-10(6) rad) corn as from cooked (121 degrees C for 30 min) corn. Therefore, the conventional cooking process for gelatinization of starch prior to its saccharification can be eliminated by irradiation. Irradiation also eliminated the necessity of sterilization of the medium and reduced the viscosity of high levels of substrate in the fermentation broth.     

Immobilization of glucoamylase and glucose oxidase in activated carbon: effects of particle size and immobilization conditions on enzyme activity and effectiveness

Glucoamylase and glucose oxidase have been immobilized on carbodiimide-treated activated carbon particles of various sizes. Loading data indicate nonuniform distribution of immobilized enzyme within the porous support particles. Catalysts with different enzyme loading and overall activities have been prepared by varying enzyme concentration in the immobilizing solution. Analysis of these results by a new method based entirely upon experimentally observable catalyst properties indicates that intrinsic catalytic activity is reduced by immobilization of both enzymes. Immobilized glucoamylase intrinsic activity decreases with increasing enzyme loading, and similar behavior is suggested by immobilized glucose oxidase data analysis. The overall activity data interpretation method should prove useful in other immobilized enzyme characterization research, especially in situations where the intraparticle distribution of immobilized enzyme is nonuniform and unknown.     

Simultaneous determination of cysteine sulfinic acid and cysteic acid in rat brain by high-performance liquid chromatography

A sensitive and specific assay method for cysteine sulfinic acid (CSA) and cysteic acid (CA) using high-performance liquid chromatography has been developed. The method includes post-column derivatization of various amino acids with o-phthalaldehyde in the presence of 2-mercaptoethanol. The column packed with cation-exchange resin ($\text{ISC-07}\text{S1504}$, Shimadzu Sci entific instruments, Inc., Kyoto, Japan) was used for obtaining general separation of amino acids except CSA and CA, while the separation of CSA and CA was achieved using a strong-base anion exchange ($\text{ISA-07}\text{S2504}$, Shimadzu Scientific Instruments) column. The fluorescence peak area for CSA was linear between 20 pmol and 5 nmol, whereas that for CA was 10 pmol to 5 nmol. The regional distribution of CSA, CA, and other amino acids in the rat brain was studied using this new assay method.     

Effects of haloperidol and sulpiride on dopamine-induced inhibition of nucleus accumbens neurons

Microiontophoretic study was performed to elucidate dopaminergic mechanism in the nucleus accumbens (Acc) of rats anesthetized with chloral hydrate. Iontophoretically applied dopamine produced an inhibition of glutamate-induced firing in 28 (62%) out of 45 Acc neurons tested. The dopamine-induced inhibition of 14 Acc neurons was clearly antagonized by simultaneous application of haloperidol, and a partial antagonism by sulpiride was observed in 3 out of 10 Acc neurons. These results indicate that dopamine produces an inhibition of the Acc neuron and that, compared to haloperidol, sulpiride is a less potent blocker of the postsynaptic dopamine receptor involved in the dopamine-induced inhibition.     

Enhancement by Putrescine of Gibberellin-Induced Elongation in Hypocotyls of Lettuce Seedlings

Effects of diamines, polyamines, and other basic amino acidson the growth of lettuce hypocotyls were investigated. Putrescine,cadaverine and agmatine enhanced the hypocotyl growth in thepresence of gibberellin, while spermidine and spermine werenon-effective. Arginine and ornithine, which may be precursorsof putrescine, had similar effect. While the growth inhibitiondue to arcaine (1,4-diguanidinobutane), which is a agmatineiminohydrolase inhibitor, was recovered by agmatine, cadaverine,putrescine, and spermidine, putrescine most effectively recoveredits growth-enhancing effect. (Received August 25, 1982; Accepted December 27, 1982)     

Effects of Cytokinin and Several Inorganic Cations on the Polyamine Content of Lettuce Cotyledons

Kinetin (4.7 x 10^–5 M) and 6-benzyladenine (2.22 x 10^–5M) were found to increase ca. 2-fold the putrescine contentin cotyledons of lettuce (Lactuca sativa L.) seedlings grownfor 3 days under fluorescent light. On the other hand, severalinorganic ions (K⁺, Na⁺, Ga⁺⁺, Mg⁺⁺) at a concentration of 3x 10^–2 M reduced the putrescine content. The combinationof kinetin with one of several inorganic ions at the same levelmarkedly increased the spermine content, but the putrescinecontent decreased; calcium and magnesium ions were less effective.The physiological significance of these findings is discussed. (Received July 4, 1982; Accepted November 6, 1982)