Effects of Exogenous Amino Acids on Iron Uptake in Relation to their Effects on Photoperiodic Flowering in Lemna paucicostata 6746

The flowering of Lemna paucicostata 6746 grown on 14-h photoperiodwas enhanced by the addition of high concentrations of ironto the medium, which also increased the endogenous iron concentration.The addition of asparagine, aspartate, glutamate, -alanine,glycine or serine to the medium also increased the endogenousiron level, resulting in the promotion of flowering. In contrast,the addition of cysteine, cystine, glutamine, arginine, threonineor phenylalanine lowered the endogenous iron level, resultingin the inhibition of flowering. Glycine and asparagine added to the medium during an inductive96-h dark period did not promote iron uptake and had no effecton flowering, but when added during the subsequent 120-h lightperiod, they promoted both iron uptake and flowering response.The increase in the endogenous iron level seems to favor floraldevelopment rather than induction of photoperiodic floweringof Lemna paucicostata 6746. (Received September 8, 1986; Accepted March 31, 1987)     

Assignment of the apolipoprotein A-I gene to 11q23 based on RFLP in a case with a partial deletion of chromosome 11, del(11)(q23.3→qter)

Summary The XmnI genotype at the apolipoprotein A-I locus was heterozygous in a boy with partial deletion of the long arm of chromosome 11, del(11)(q23.3qter). The apolipoprotein A-I gene, previously assigned to chromosome region 11q23q24, has been more specifically localized to 11q23 by excluding the region 11q24qter.     

Light and electron microscopic immunocytochemistry on the localization of 3β-hydroxysteroid dehydrogenase/isomerase in the bovine adrenal cortical cells

Summary The localization of 3-hydroxysteroid dehydrogenase/isomerase (3-HSD) was studied in bovine adrenal glands by light as well as electron microscopic immunocytochemistry, using anti-bovine adrenal 3-HSD antibody. With light microscopy the cytoplasm of the glomerulosa cells was weakly immunostained, while that of the fasciculata-reticularis cells was intensely immunostained though both the capsular connective tissue cells and the medullary cells were entirely negative for this reaction. Electron microscopic immunocytochemistry revealed that the positive reaction products for 3-HSD were present on the membrane of smooth endoplasmic reticulum of the cortical cells, especially that of the fasciculata and reticularis cells. Other cell organelles such as mitochondria and Golgi apparatus were entirely negative. The present results indicate that 3-HSD is present in the membrane of smooth endoplasmic reticulum of bovine adrenal cortical cells.Supported by grants from the Ministry of Education Science and Culture, Japan     

Rotation and protein-protein interactions of cytochrome P-450 in the inner membrane of adrenocortical mitochondria

Rotational diffusion of the total cytochrome P-450 (P-450scc plus P-45011 beta) in bovine adrenocortical mitochondria was examined by observing the decay of absorption anisotropy, r(t), after photolysis of the hemo.CO complex by a vertically polarized laser flash. Analysis of r(t) was based on a "rotation-about-membrane normal" model. The measurements were used to investigate intermolecular interactions of cytochrome P-450 with other membrane proteins. The absorption anisotropy decayed within 1 ms to a time-independent value. Rotational diffusion of cytochrome P-450 was dependent on the presence and absence of deoxycorticosterone (DOC), a substrate for cytochrome P-45011 beta. The observed value for the normalized time-independent anisotropy r(infinity)/r(0) and the average rotational relaxation time phi are r(infinity)/r(0) = 0.88 and phi = 233 microseconds when DOC is absent, and r(infinity)/r(0) = 0.65 and phi = 350 microseconds when DOC is present. Judging from the phi value, rotating P-450 is not a monomeric molecule, but would be a small microaggregate with an average diameter of about 120 A. A significantly high value of r(infinity)/r(0) implies co-existence immobile populations of cytochrome P-450. Based on the assumption that the heme angle tilts 55 degrees from the membrane plane (Gut et al. (1983) J. Biol. Chem. 258, 8588-8594), 65% (when DOC is present) or 88% (when DOC is absent) of cytochrome P-450 in mitochondria is immobilized within the experimental time range of 2 ms due to the presence of immobile protein microaggregates.(ABSTRACT TRUNCATED AT 250 WORDS)     

Coordination structures and reactivities of compound II in iron and manganese horseradish peroxidases. A resonance Raman study

Resonance Raman investigations on compound II of native, diacetyldeuteroheme-, and manganese-substituted horseradish peroxidase (isozyme C) revealed that the metal-oxygen linkage in the compound differed from one another in its bond strength and/or structure. Fe(IV) = O stretching frequency for compound II of native enzyme was pH sensitive, giving the Raman line at 772 and 789 cm-1 at pH 7 and 10, respectively. The results confirmed the presence of a hydrogen bond between the oxo-ligand and a nearby amino acid residue (Sitter, A. J., Reczek, C. M., and Terner, J. (1985) J. Biol. Chem. 260, 7515-7522). The Fe(IV) = O stretch for compound II of diacetylheme-enzyme was located at 781 cm-1 at pH 7 which was 9 cm-1 higher than that of native enzyme compound II. At pH 10, however, the Fe(IV) = O stretch was found at 790 cm-1, essentially the same frequency as that of native enzyme compound II. The pK value for the pH transition, 8.5, was also the same as that of native compound II. Unlike in native enzyme, D2O-H2O exchange did not cause a shift of the Fe(IV) = O frequency of diacetylheme-enzyme. Thus, the metal-oxygen bond at pH 7 was stronger in diacetylheme-enzyme due to a weaker hydrogen bonding to the oxo-ligand, while the Fe(IV) = O bond strength became essentially the same between both enzymes at alkaline pH upon disruption of the hydrogen bond. A much lower reactivity of the diacetylheme-enzyme compound II was accounted to be due to the weaker hydrogen bond. Compound II of manganese-substituted enzyme exhibited Mn(IV)-oxygen stretch about 630 cm-1, which was pH insensitive but down-shifted by 18 cm-1 upon the D2O-H2O exchange. The finding indicates that its structure is in Mn(IV)-OH, where the proton is exchangeable with a water proton. These results establish that the structure of native enzyme compound II is Fe(IV) = O but not Fe(IV)-OH.     

Properties of porcine platelet myosin. II. Shape change of the molecule

Porcine platelet myosin molecules were examined by electron microscopy for changes in their shape. At high ionic strength, the molecules were morphologically indistinguishable from skeletal muscle myosin, except for a slight difference in the bent regions of their tails. At physiological ionic strength, however, the following important difference was observed between the two myosins. Unlike skeletal muscle myosin, the filaments of nonphosphorylated platelet myosin could be disassembled by stoichiometric ATP into a monomeric form with sharply bent or folded tail, and reassembled after ATP hydrolysis. Similar disassembly changes could be induced by various nucleotide triphosphates (CTP, GTP, ITP, and UTP) and to a lesser extent by ADP, AMP, and AMPPNP. These results suggest that ATP binds to the hydrolytic sites in platelet myosin molecule and induces the molecular shape change.     

Infrared spectra of carbon monoxide complexes of indoleamine 2,3-dioxygenase and L-tryptophan 2,3-dioxygenases. Effects of substrates on the CO-stretching frequencies

Carbonmonoxy indoleamine 2,3-dioxygenase from rabbit small intestine exhibited two CO stretch bands at 1953 and 1933 cm-1 with half-band widths (delta v 1/2) of both approximately 15 cm-1. Upon addition of an excess amount of L-tryptophan, the substrate, the spectrum changed into that with an intense single band at 1902 cm-1 with the delta v 1/2 of 15 cm-1. Carbonmonoxy L-tryptophan 2,3-dioxygenase of Pseudomonas acidovorans in the absence of L-tryptophan showed a fused CO stretch band which consists of two components at 1965 and 1958 cm-1 (delta v 1/2 for the fused band; 25 cm-1), which was converted into a sharp single band at 1968 cm-1 (delta v 1/2; 10 cm-1) upon addition of excess L-tryptophan. On the other hand, CO complex of rat liver L-tryptophan 2,3-dioxygenase in the absence of L-tryptophan gave a spectrum with a poorly defined peak around 1961 cm-1. By the addition of L-tryptophan, the spectrum changed into that with two distinct bands at 1972 and 1920 cm-1 (delta v 1/2; 6 and 13 cm-1, respectively). These spectra were insensitive to pH in a range where the enzymes were not denatured (neutral to near pH 9). The infrared spectra of the carbonmonoxy enzymes were also affected by the addition of certain effectors such as skatole and alpha-methyl-DL-tryptophan, which facilitate the binding of L-tryptophan to the catalytic site of intestinal and Pseudomonas enzymes, respectively. However, the changes were of different types from those by the saturating amount of L-tryptophan. Possible mechanisms for these phenomena are discussed in relation to the structure of the heme-CO complex in these heme-containing dioxygenases.     

Ontogenesis of gastrin cells in the pyloric antrum and duodenum of the mouse

Summary Ontogenesis of gastrin cells was studied in the pyloroduodenal mucosa of the mouse using anti-human G17 serum, R-1301, and anti-human G34(1–15) serum, R-2703. R-1301-immunostained cells first appeared in the pyloric mucosa of 14-day-old fetuses. Cells stained with both R-1301 and R-2703 appeared immediately after birth, and gradually increased in number to the adult level. Most R-1301-reactive cells were also reactive to R-2703, whereas some cells that reacted with R-1301 exhibited very weak or no reaction with R-2703. The discrepancy between these two immunoreactivities is discussed.In the duodenum, a considerable number of R-1301-reactive cells were present from the perinatal stage and through out adult development. A few R-2703-reactive cells were seen in the duodenum of young mice but not of the adult.     

Culture of intramural cardiac ganglia of the newborn guinea-pig

Summary The present study describes the ultrastructure of non-neuronal cells and their interrelationships with intracardiac neurones present in cultures dissociated atria and interatrial septum from newborn guinea-pig. When compared with the in situ preparation, most of these features in culture were similar to those observed in situ, but some differences were also apparent. Both mature and immature Schwann cells were observed in culture, and as in situ, the latter were closely associated with intracardiac neurones, whilst the former were more widely separated. The ultrastructure of satellite cells was more variable in culture than in situ: three general types were distinguished on the basis of their 10-nm filament content. This variation could be due to conditions of culture. Interstitial cells were present in culture and closely resembled those described in situ, although there was less space between cultured interstitial cells and their associated cells. Many fibroblasts, some myoblasts and a few mast cells were also found in the culture preparations.     

12-O-tetradecanoylphorbol 13-acetate induces DNA cleavage at linker regions in mouse thymocytes

A phorbol ester, 12-O-tetradecanoylphorbol 13-acetate (TPA), induced the cleavage of nuclear DNA at linker regions in cultured mouse thymocytes. Similar DNA fragmentation was induced by 1-oleoyl-2-acetyl-glycerol, a synthetic diacylglycerol, but not by 4 alpha-phorbol-12,13 didecanoate. The DNA fragmentation was inhibited by 1-(5-isoquinoline-sulfonyl)-2-methyl-piperazine dihydrochloride, an inhibitor of protein kinase C, as well as actinomycin D and cycloheximide. It appears that TPA induces DNA cleavage through activation of protein kinase C and synthesis of yet unidentified protein(s). That the inhibition of DNA fragmentation was accompanied by a reduction in cell lysis suggests a causal relationship between DNA fragmentation and cell death.