The terminal oxidase of Photobacterium phosphoreum. A novel cytochrome

The terminal oxidase of Photobacterium phosphoreum has been purified to the electrophoretically homogeneous state and some of its properties have been studied.The enzyme catalyses oxidation of ascorbate in the presence of phenazine methosulphate or N,N,N′,N′-tetramethyl-p-phenylenediamine. The reaction is inhibited by cyanide. Nitrite at comparatively high concentrations inhibits the enzyme, but the enzyme does not catalyse nitrite reduction with ascorbate plus the electron mediator as the electron donor.The enzyme shows the absorption peaks at 632, 565, 534 and 436 nm in the reduced form. It has two kinds of haems: protohaem and haem d. Namely, the enzyme is a ‘cytochrome bd’-type oxidase; a novel cytochrome.     

Isolation and identification of substances inducing formation of tracheary elements in cultured carrot-root slices

Data are presented on the cytokinin status of seeds and seed components, at different stages of development in Phaseolus coccineus L., as determined with the soybean callus growth bioassay: A change in cytokinin types according to developmental stage occurred: from biologically very active less polar types (zeatin=Z) at early stages to more polar types (zeatin glucoside=Z₉G and zeatin riboside=Zr), with relatively low biological activity, at intermediate and late stages of seed development: When cytokinins were analyzed separately in embryos (embryo proper) and suspensors at two embryonic stages: heart-shaped (A) and middle cotyledonary embryos (stage B) respectively, it was found that: i) at stage A, the suspensor showed cytokinin activity at the level of Z, 2iPA (2-isopentenyladenosine) and Zr, whereas more polar cytokinins (Z₉G, Zr) were present in the embryo; ii) at stage B, when the embryo seems to become autonomous for cytokinin supply, there was a relative abundance of active cytokinins (Z, 2iPA) in the embryo to which Z₉G activity in the suspensor corresponded. It is concluded that the suspensor plays an essential role in embryogenesis by acting as a hormone source to the early embryo.Abbreviations GA gibberellic acid - 2iPA 2-isopentenyladenosine - Stage A heart-shaped embryo - siage B middle cotyledonary embryo - Z zeatin - Z₉G zeatin glucoside - Zr Zeatin riboside     

Effect of 7-fluoro prostacyclin,a stable prostacyclin analogue,on cAMP accumulation and prostaglandin binding in mastocytoma P-815 cells

The effect of 7-fluoro proscyclilin (PGI₂-F), a chemically stable analogue of prostacyclin, on cAMP accumulation in and [³H]PGE binding to mastocytoma P-815 cells was compared with those of the Na salt and methyl ester of prostacyclin (PGI₂Na or PGI₂Me), which are rapidly inactivated in aqueous solution or metabolized in the tissue.PGIF was as effective as PGI₂Me, and slightly less effective than PGI₂Na in stimulating cAMP accumulation in mastocytoma cells and rabbit platelets. PGI₂F was also more stable than PGI₂Me or PGI₂Na, and retained its original cAMP elevating activity even after incubation with or without cells for 4 h at 37°C. Cells which had been exposed to PGI₂F and then washed free of unbound reagent continued to produced cAMP for more than 3 h. PGI₂F was also as effective as PGE₁ or PGE₂ in displacing [³H]PGE₂ bound to the cells. Non-competitive inhibition by PGI₂F or PGI₂Me of [³H]PGE₂ binding to the cells, with apparent K_is of 1.29 μM and 1.13 μM, respectively, indicates the presence of different receptors for PGE₂ and for PGI₂F or PGI₂Me in mastocytoma P-815 cells.     

Association of neutral α-glucosidase with cytoplasmic granules of peritoneal macrophages

A neutral α-glucosidase (EC 3.2.1.20) activity was shown to be associated with granules which are sedimentable at 10 000 g after differential centrifugation of mouse peritoneal macrophage homogenates. When the post-nuclear supernatant was centrifuged in a sucrose density gradient, high activities for neutral α-glucosidase and β-glucuronidase (EC 3.2.1.31) were detected in the bottom fractions because of aggregation of the granules. Neutral α-glucosidase-containing granules were completely disaggregated by the addition of 20 units/ml of heparin and 10 mM Tris-HCl (pH 7.2), which caused only a partial disaggregation of β-glucuronidase-containing granules. The addition of a high concentration of heparin, Tris buffer, or KCl to the gradient gave the same patterns of disaggregation of the granules. Under the condition in which about 50% of the total β-glucuronidase activity was released into the medium, depending on phagocytosis, very little α-glucosidase was released. These observations suggested that neutral α-glucosidase may localize in non-lysosomal granules.     

Crucial factors determining the spatio-temporal distribution patterns of threeAthalia sawflies feeding on common cruciferous plants

Three Athalia sawflies, A. japonica, A. rosae and A. infumata, feeding on cruciferous plants, coexist in Japan. However, it is not known what ecological strategies they use and what environmental factors are crucial to such strategies. I attempted to explain these questions by examining the relationship between the spatio-temporal distribution patterns of three Athalia sawflies and their habitats in three districts (Lowland, Intermediate and Mountain). The three sawflies have different spatio-temporal distribution patterns, though they usually used common cruciferous plants. A. japonica was abundant in spring and autumn but disappeared during summer in all the districts. In the Lowland, populations of A. rosae and A. infumata, like that of A. japonica, crashed in summer. However A. rosae occurred mainly in summer in the Intermediate and Mountain. Although A. infumata occurred in the same seasons as A. rosae in all districts, population levels of A. infumata were always lower than those of A. rosae. The crucial factors controlling their population patterns were the availability of host plants and temperature. Population crashes of A. rosae and A. infumata were due to food depletion, and those of A. japonica were due to heat stress. On the other hand, their population patterns may be interpreted as phenological synchronization with their original host plants, though they all existed on common cruciferous plants. The three sawflies may have evolved different strategies to escape from unfavorable habitat conditions. Such strategies are speculated to be summer diapause in A. japonica, long distance migration in A. rosae, and local dispersal in A. infumata.     

Translocation of colicin E1 through cytoplasmic membrane of Escherichia coli

The product of the malE—lacZ gene fusion was reported to compete with some proteins including outer membrane lipoprotein in the protein translocation across the Echerichia coli membrane. The fusion product also inhibited colicin E1 export. Furthermore, globomycin, which accumulated prolipoprotein in the membrane, inhibited the translocation of colicin E1 in the wild-type cells, but not in lipoprotein-negative mutant cells. Since colicin E1 contains the internal signal-like sequence [Proc. Natl. Acad. Sci. USA (1982) 79, 2827–2831], these results suggest that colicin E1 is exported by the aid of this sequence at a common site for maltose-binding protein and lipoprotein translocation.     

Glucans in the Cell Walls Regenerated from Vinca rosea Protoplasts

Protoplasts prepared from suspension-cultured Vinca rosea cellswere cultured for 5 days. The cell walls regenerated from theprotoplasts were mainly composed of glucans having 1,3- and1,4-linkages. To investigate the molecular species, these glucanswere separated into four fractions: EDTA (50 mM, pH 4.5)-soluble(fraction E), KOH (24%)- soluble but not precipitatable by neutralizationwith acetic acid (fraction K-S), KOH (24%)-soluble and precipitatableby neutralization with acetic acid (fraction K-P), and KOH (24%)-insoluble(fraction C). By means of sugar composition analysis, methylationanalysis, periodate oxidation and enzymatic digestion, the molecularspecies of the glucans contained in the regenerated cell wallswere deduced to be ß-1,4-glucan (cellulose) and ß-1,3-glucan.Fraction C was mainly composed of ß-1,4-glucan; ß-1,3-glucanwas mainly recovered in fraction K-P. The ß-l,3-glucanwas soluble in dilute alkali solution, but was only slightlysoluble in water. The ß-1,3-glucan had an essentiallyunbranched structure, and its weight average molecular weightestimated by gel permeation chromatography was 4.5–5.0x 10⁴. ¹ Present address: Division of Environmental Biology, NationalInstitute for Environmental Studies, Yatabe, Tsukuba, Ibaraki305, Japan (Received May 21, 1981; Accepted October 13, 1981)     

Histidine decarboxylase activities in mutant mice deficient in mast cells

The histamine contents were very low in the whole bodies of various types of mutant mice (W^v/W^v, W^v/W, W/W), in which the number of mast cells was decreased, but the L-histidine decarboxylase activities in these mutant mice were not much lower than in control wild type mice. These findings suggest the presence of high histidine decarboxylase activity in cells other than mast cells. Histidine decarboxylase in the whole body of mice was difficult to assay, because the enzyme was rapidly destroyed by proteases, but inclusion of a protease inhibitor, such as Leupeptin, Antipain, Chymostatin, or Pepstatin in the assay mixture permitted the accurate assay of histidine decarboxylase in crude extracts.     

The “happy puppet” syndrome in two siblings

Summary Disomic and trisomic cells of a patient with Down syndrome mosaic were used to study the effect of the additional chromosome 21 against an identical genetic background. The frequency of Ag staining and the participation in satellite associations were determined for each pair of acrocentric chromosomes. The additional chromosome 21 of the trisomic cells and its homologues proved to be regularly Ag positive. Therefore the trisomic cells showed more Ag positive chromosomes and more satellite associations per cell than the diploid cells. Thus, no compensation for the additional rRNA-gene dose could be found in the cells of the trisomic line.