Amendments to (63)Ni production calculation for Hiroshima by Takamiya et al. and DS02 fluence data by Egbert et al.

In a previous paper, Takamiya et al. calculated (63)Ni production in copper samples exposed to the Hiroshima atomic bomb. More specifically, they used their experimental cross-section values of the (63)Cu(n,p)(63)Ni reaction and compared the result with that of the corresponding calculation in the radiation dosimetry system DS02, which used another set of cross-section values. These results were different, and the following two reasons were found: typographical errors in several energy boundary values in the DS02 report that was also used in the calculation by Takamiya et al. and an inappropriate assumption on the cross-section values of the low neutron energy region in the calculation by Takamiya et al. These two issues are described and amended in the present report.

Activity-dependent secretion of neuronal activity regulated pentraxin from vasopressin neurons into the systemic circulation.

Neuronal activity regulated pentraxin (Narp) is a secreted, synaptic protein that has been implicated in modulating synaptic transmission. However, it is unclear how Narp secretion is regulated. Since we noted prominent Narp immunostaining in vasopressin neurons of the hypothalamus and in the posterior pituitary, we assessed whether it, like vasopressin, is released into the systemic circulation in an activity-dependent fashion. Consistent with this hypothesis, electron microscopic studies of the posterior pituitary demonstrated that Narp is located in secretory vesicles containing vasopressin. Using affinity chromatography, we detected Narp in plasma and found that these levels are markedly decreased by hypophysectomy. In addition, we confirmed that injection of a viral Narp construct into the hypothalamus restores plasma Narp levels in Narp knockout mice. In checking for activity-dependent secretion of Narp from the posterior pituitary, we found that several stimuli known to trigger vasopressin release, i.e. hypovolemia, dehydration and endotoxin, elevate plasma Narp levels. Taken together, these findings provide compelling evidence that Narp is secreted from vasopressin neurons in an activity-dependent fashion.

Excitation function for 63Cu(n,p)63Ni reaction in neutron energy range up to 15 MeV.

The excitation function for the (63)Cu(n,p)(63)Ni reaction has been measured by activation method using the 4.5 MV Dynamitron accelerator of the Fast Neutron Laboratory of Tohoku University. Copper plates and hollow spherical copper shells were irradiated by neutrons of various energy up to 14.9 MeV produced by the T(p,n), D(d,n), and T(d,n) reactions. The (63)Ni produced in the irradiated copper target was chemically separated. The beta-rays emitted from the extracted (63)Ni were measured by a liquid scintillation method. The cross sections obtained were compared with the evaluated data files of JENDL-3.3, ENDF/B-VI and FENDL/A-2.0. Consequently, it is found that FENDL/A-2.0 is consistent with our experimental data in the energy range studied in this work. The effect of proton shell appeared in the excitation function obtained is also discussed.

Target preparation by the precipitation method for nuclear reactions.

A technique for preparing nuclear reaction targets of various thicknesses was developed by using common filtration technique of hydroxide precipitates with a porous Al(2)O(3) membrane filter. Uniformity was found to be within a few % in each thickness. Durability for beam irradiation was also confirmed. The preparation procedure is convenient and the method is appropriate for several target materials, including not only precious materials but also radioactive materials with low contamination.

Degradation pathway(s) of chlorophyll: what has gene cloning revealed?

The mechanism responsible for the degreening of plants and the degradation of chlorophyll was unclear for many years. However, recent studies have identified the colorless intermediates and helped to construct a basic pathway for degradation. After the successive removal of phytol and Mg21 from the chlorophyll molecule by chlorophyllase and 'Mg dechelatase', pheophorbide a is cleaved and reduced to yield a colorless, open tetrapyrrole intermediate. After further modifications, this is finally transported to the vacuole. Cloning the genes for chlorophyllase isozymes and the reductase should help to elucidate the physiological roles of each enzyme at a molecular level.

Nature of photochemical reactions in chromatophores of Chromatium D. III. Heterogeneity of the photosynthetic units.

The effect of isooctane extraction on photooxidation of c-type cytochromes was investigated in Chromatium chromatophores. Photooxidation of cytochrome c-555 was not affected by isooctane-extraction was abolished by thorough extraction of ubiquinone-7, but the quantum yield of the cytochrome photooxidation remained unchanged until 90% of the total ubiquinone was extracted. The photooxidation of cytochrome c-552 was recovered by the addition of ubiquinone-7 but not by menaquinone. A dark incubation of sufficient length was needed for maximal quantum yield of cytochrome c-555 photooxidation in the presence of 30 mM ascorbate. It is proposed that there are two types of photosynthetic units (or associations of molecules involved in the primary redox reactions) in Chromatium chromatophores. The combinations of primary electron donor-reaction center chlorophyll-primary electron acceptor may be cytochrome c-552-P890=ubiquinone in one type and cytochrome c-555-P890-X in another.

Ubiquinone in Rhodopseudomonas sphaeroides. Some thermodynamic properties.

In Rhodopseudomonas sphaeroides chromatophores there are 25 +/- 3 ubiquinone (Q) molecules/reaction center protein. They comprise several thermodynamically and functionally different ubiquinone complements. There are approx. 19 ubiquinones (Em7 = 90 mV) in the main ubiquinone complement which, within experimental resolution, appears thermodynamically homogenous and follows the redox reaction Q + 2e + 2H+ in equilibrium with QH2 from pH 5--9. A method which takes advantage of the 2H+ bound/molecule of Q reduced is described for measuring the time course of light-activated reaction center-driven reduction and oxidation of the 19 Q complement. No stable semiquinones were detected in the constitutents of the 19 Q complement. There are approx. 6 ubiquinones of lower Em which are currently unaccounted for, although one or possibly two of these can be assigned to the quinones of the reaction center protein. The remainder may be associated with the NADH-ubiquinone oxidoreductase.

Delayed fluorescence from bacteriochlorophyll in Chromatium vinosum chromatophores.

Delayed fluorescence from bacteriochlorophyll in Chromatium vinosum chromatophores was studied at room temperature and under intermittent illuminations. The decay of delayed fluorescence was constituted of two components; a fast component decayed with a half time of about 8 ms, a slow one decayed in parallel with the reduction of photooxidized bacteriochlorophyll (P+) with a half time of 100-200 ms. The biphasic decay of delayed fluorescence indicated that a rapid equilibrium was established between the primary electron acceptor and the secondary acceptor. In the presence of o-phenanthroline, the time course of the decay of delayed fluorescence was identical with that of the reduction of P+ in reaction center-rich subchromatophore particles, although they did not necessarily coincide with each other in "intact" chromatophores. The intensity of the slow component was increased and the decay was accelerated at basic pH values. Reagents that dissipate the proton gradient across the chromatophore membranes such as carbonylcyanide m-chlorophenylhydrazone (CCCP) and nigericin accelerated the decay of the slow component. These effects are probably resulting from changes in internal pH of chromatophore vesicles. Reagents that dissipate the membrane potential such as CCCP and valinomycin decreased the intensity.

Novel functions of complex carbohydrates elucidated by the mutant mice of glycosyltransferase genes.

Complex carbohydrates consist of carbohydrate moieties and protein or lipid portions, resulting in the formation of glycoproteins, proteoglycans or glycosphingolipids. The polymorphic carbohydrate structures are believed to contain profound biological implications which are important in cell-cell or cell-extracellular matrix interactions. A number of studies to delineate the roles of carbohydrates have been performed, and demonstrated definite changes in their profiles, cellular phenotypic changes or, sometimes, morphological and functional changes in tissues after modification of their structures. Recent successes in the isolation of glycosyltransferase genes and their modification enzyme genes has enabled clearer demonstrations of the roles of complex carbohydrates. In particular, genetic modification of glycosyltransferase genes in mice can elucidate the biological significances of their products in vivo. Here, we summarize recent advances in the understanding of the roles of complex carbohydrates provided from studies of gene knock-out mice of glycosyltransferase and modification enzyme genes focusing on novel functions which had not been expected.

Gangliosides are the binding substances in neural cells for tetanus and botulinum toxins in mice.

We used the knockout mice lacking gangliosides and evaluated their response to tetanus and botulinum toxins. We found that tetanus toxin and botulinum type A or B toxin was less toxic in the knockout mice. We conclude that the toxins bind to the gangliosides on the synapses in the initial step of intoxication prior to penetration of the toxins into the neural cells.

Electrogenic events in the ubiquinone-cytochrome b/c2 oxidoreductase of Rhodopseudomonas sphaeroides.

The reductant of ferricytochrome c2 in Rhodopseudomonas sphaeroides is a component, Z, which has an equilibrium oxidation-reduction reaction involving two electrons and two protons with a midpoint potential of 155 mV at pH 7. Under energy coupled conditions, the reduction of ferricytochrome c2 by ZH2 is obligatorily coupled to an apparently electrogenic reaction which is monitored by a red shift of the endogeneous carotenoids. Both ferricytochrome c2 reduction and the associated carotenoid bandshift are similarly affected by the concentrations of ZH2 and ferricytochrome c2, pH, temperature the inhibitors diphenylamine and antimycin, and the presence of ubiquinone. The second-order rate constant for ferricytochrome c2 reduction at pH 7.0 and at 24 degrees C was 2 - 10(9) M-1 - s-1, but this varied with pH, being 5.1 - 10(8) M-1 = s-1 at pH 5.2 and 4.3 - 10(9) M-1 - s-1 at pH 9.3. At pH 7 the reaction had an activation energy of 10.3 kcal/mol.

Application of a CZT detector to in situ environmental radioactivity measurement in the Fukushima area.

Instead of conventional Ge semiconductor detectors and NaI(Tl) scintillation spectrometers, an application of a CdZnTe semiconductor (CZT) whose crystal has the dimension of 1 cm cubic to the in situ environmental radioactivity measurement was attempted in deeply affected areas in Fukushima region. Results of deposition density on soil for (134)Cs/(137)Cs obtained seemed consistent, comparing obtained results with those measured by the Japanese government.

Monitoring of methyl jasmonate-responsive genes in Arabidopsis by cDNA macroarray: self-activation of jasmonic acid biosynthesis and crosstalk with other phytohormone signaling pathways.

Jasmonates mediate various physiological events in plant cells such as defense responses, flowering, and senescence through intracellular and intercellular signaling pathways, and the expression of a large number of genes appears to be regulated by jasmonates. In order to obtain information on the regulatory network of jasmonate-responsive genes (JRGs) in Arabidopsis thaliana (Arabidopsis), we screened 2880 cDNA clones for jasmonate responsiveness by a cDNA macroarray procedure. Since many of the JRGs reported so far have been identified in leaf tissues, the cDNA clones used were chosen from a non-redundant EST library that was prepared from above-ground organs. Hybridization to the filters was achieved using alpha-33P-labeled single-strand DNAs synthesized from mRNAs obtained from methyl jasmonate (MeJA)-treated and untreated Arabidopsis seedlings. Data analysis identified 41 JRGs whose mRNA levels were changed by more than three fold in response to MeJA. This was confirmed by Northern blot analysis by using eight representatives. Among the 41 JRGs identified, 5 genes were JA biosynthesis genes and 3 genes were involved in other signaling pathways (ethylene, auxin, and salicylic acid). These results suggest the existence of a positive feedback regulatory system for JA biosynthesis and the possibility of crosstalk between JA signaling and other signaling pathways.

Molecular cloning and functional expression of the second mouse nm23/NDP kinase gene, nm23-M2.

A new murine cDNA of nm23/NDP kinase was isolated. A RT-PCR product was obtained from the normal mouse liver mRNA with primers designed for the human nm23-H2 gene. The product was used as a probe to screen a cDNA library from the murine melanoma cell line, B16, and two clones containing the entire open reading frame were obtained. It was predicted that the DNA sequence encoded 152 amino acids which was 98% identical to the nm23-H2 protein. The entire nm23-M1 and -M2 gene-coding regions were translated as fusion proteins with a glutathione S-transferase. These fusion proteins displayed NDP kinase activities.

A putative transcription factor binding to the upstream region of the puf operon in Rhodobacter sphaeroides.

Gel shift assays of the upstream region of the puf operon in Rhodobacter sphaeroides were performed using cell-free extracts from cells grown under various culture conditions. The results suggested that a protein binding to the upstream region functioned as a repressor-like substance of the expression of the operon by oxygen tension or light. The density of the shifted band of cell-free extracts from cells irradiated with blue light under semi-aerobic conditions was higher than that with red light. Phosphatase treatment of the cell-free extracts strongly increased the DNA-binding affinity of the protein.

Differential expression of isoforms of PSD-95 binding protein (GKAP/SAPAP1) during rat brain development.

PSD-95/SAP90, which binds to the C-terminus of NMDA receptor and Shaker-type potassium channel, is one of the major postsynaptic density proteins. Recently, novel classes of proteins interacting with the guanylate kinase domain of PSD-95 have been identified, guanylate kinase-associated protein (GKAP) and SAP90/PSD-95-associated proteins (SAPAPs). Here we report the isolation of new isoforms of PSD-95 binding protein (GKAP/SAPAP1) using the yeast two-hybrid system. The isolated protein directly interacts with the guanylate kinase domain of PSD-95. Northern blot analyses revealed that the expression of these isoforms containing distinct N-terminal sequences is differentially regulated during brain development. The present findings suggest that each isoform of the PSD-95 binding protein is differentially expressed in a development-dependent manner and may be involved in the complex formation of PSD-95 and channel/receptors at the postsynaptic density.

Two distinct isopentenyl diphosphate isomerases in cytosol and plastid are differentially induced by environmental stresses in tobacco.

Two distinct cDNA clones (IPI1 and IPI2) encoding IPI were isolated from Nicotiana tabacum. In situ expression of isopentenyl diphosphate isomerase-1 (IPI1)- and IPI2-green fluorescent protein fusion constructs revealed that IPI1 and IPI2 were localized in chloroplast and cytosol, respectively. The level of IPI1 mRNA was increased under high-salt and high-light stress conditions, while that of IPI2 mRNA was increased under high-salt and cold stress conditions. Both IPI transcripts were increased in an abscisic acid-independent manner. This is the first report of a cytosolic IPI. The results indicated that two distinct IPIs were differentially induced in response to stress.

Identification and light-induced expression of a novel gene of NADPH-protochlorophyllide oxidoreductase isoform in Arabidopsis thaliana.

In Arabidopsis thaliana, we identified a novel gene of a NADPH-protochlorophyllide oxidoreductase (POR) isoform, which catalyzes the light-dependent protochlorophyllide a reduction in the chlorophyll (Chl) biosynthetic pathway. The deduced amino acid sequence of the novel POR isoform (PORC) showed significant identities ( approximately 75%) with the previously isolated two POR isoforms of A. thaliana. Contrasting with these POR isoforms, the PORC transcript increased in etiolated seedlings by illumination, and was dominantly expressed in immature and mature tissues. The present results demonstrated that Chl biosynthesis and chloroplast biogenesis in A. thaliana are controlled by three POR isoforms, which are differentially controlled by light and development.

T cell receptor-mediated stimulation of mouse thymocytes induces up-regulation of the GM2/GD2 synthase gene.

cDNA clones of the mouse GM2/GD2 synthase (EC 2.4.1.92) gene were isolated, and their analyses revealed that the protein has a type II transmembrane structure with 533 amino acids, which was very similar to the human homolog except for the mRNA size. The mRNA level in thymocytes dramatically increased after treatment with anti-CD3 monoclonal antibody, whereas it was not elevated when treated with prostaglandin E2. In situ hybridization showed an elevation of mRNA levels in medullar thymocytes, suggesting that T cell receptor-mediated signaling induces up-regulation of the GM2/GD2 synthase gene in mature thymocytes.

Induction of a novel cytochrome P450 (CYP93 family) by methyl jasmonate in soybean suspension-cultured cells.

We isolated a cDNA encoding a novel cytochrome P450 (CYP93A1) from soybean suspension-cultured cells that had been treated with methyl jasmonate (MeJA). The amino acid sequence of the gene product had 30-40% identity with those of other plant P450s. The protein contained the heme-binding domain which is highly conserved among plant P450s. Transcription of the cytochrome P450 gene in soybean cells was induced by 30 microM MeJA even in the presence of cycloheximide, and reached maximum level 6 h after MeJA treatment. This is the first report of a plant cytochrome P450 gene whose transcription is induced by MeJA even without protein synthesis.