The physiological role of lipoxygenase in ethylene formation from 1-aminocyclopropane-1-carboxylic acid in oat leaves

In order to understand the physiological significance of the in-vitro lipoxygenase (EC 1.13.11.12)-mediated ethylene-forming system (J.F. Bousquet and K.V. Thimann 1984, Proc. Natl. Acad. Sci. USA 81, 1724–1727), its characteristics were compared to those of an in-vivo ethylene-forming system. While oat (Avena sativa L.) leaves, as other plant tissues, preferentially converted only one of the 1-amino-2-ethylcyclopropane-1-carboxylic acid (AEC) isomers to 1-butene, the lipoxygenase system converted all four AEC isomers to 1-butene with nearly equal efficiencies. While the in-vivo ethylene-forming system of oat leaves was saturable with ACC with a K_m of 16 M, the lipoxygenase system was not saturated with ACC even at 10 mM. In contrast to the in-vivo results, only 10% of the ACC consumed in the lipoxygenase system was converted to ethylene, indicating that the reaction is not specific for ethylene formation. Increased ACC-dependent ethylene production in oat leaves following pretreatment with linoleic acid has been inferred as evidence of the involvement of lipoxygenase in ethylene production. We found that pretreating oat leaves with linoleic acid resulted in increased ACC uptake and thereby increased ethylene production. A similar effect was observed with oleic acid, which is not a substrate of lipoxygenase. Since linoleic acid hydroperoxide can substitute for lipoxygenase and linoleic acid in this system, it is assumed that the alkoxy radicals generated during the decomposion of linoleic acid hydroperoxide are responsible for the degradation of ACC to ethylene. Our results collectively indicate that the reported lipoxygenase system is not the in-vivo ethylene-forming enzyme.Abbreviations ACC 1-Aminocyclopropane-1-carboxylic acid - AEC 1-amino-2-ethylcyclopropane-1-carboxylic acid - Epps N-(2-hydroxyethyl)-piperazine-N-3-propanesulfonic acid - LH linoleic acid - LOOH linoleic acid hydroperoxide - pyridoxal-P pyridoxal-phosphate This work was presented at the 12th International Conference on Plant Growth Substances, Heidelberg, FRG, August 1985 (Abstract No. PO 5-52)     

Modulation of the immune response to tumors by a novel synthetic compound,N-[4-[(4-fluorophenyl)sulfonyl]phenyl] acetamide (CL 259,763)

Summary CL 259,763, N-[4-[(4-fluorophenyl)sulfonyl]phenyl] acetamide, is an orally active compound capable of modifying the reactivity of certain lymphoid cell populations affected by the growth of a tumor. The compound augmented the response of lymphocytes from tumor-primed animals to syngeneic tumor cells, resulting in a marked increase in tumor cell destruction. Likewise, it enhanced macrophage inhibitory effects on the growth of tumor cells in vitro. These activated macrophages were detectable in peritoneal exudates of treated mice 4 to 12 days after receiving a single oral dose of CL 259,763, with peak activity being demonstrable by day 7. The compound also restored the alloreactivity of lymphocytes from immunodepressed mice bearing the Lieberman plasma cell tumor, possibly by interferring with suppressor cells. Macrophages and lymphocytes from treated mice released significantly more IL-1 and IL-2-like factors in culture than did the control counterparts. Sera from treated mice also possessed more colony stimulating factor than those from normal mice. Immunoadjuvant effects were evident when the compound was administered with an inactivated L1210 leukemia vaccine and it enhanced the effectiveness of cytotoxic chemotherapy when given to mice challenged with P388 murine leukemia. These immunomodulating effects of CL 259,763 may hopefully be exploited in efforts to augment the immune response of the host to a progressively growing tumor.     

连续性空间分布型模型与应用研究

本文对Pearson-Ⅲ分布与指数分布的空间分布型特征进行了探讨,发现它们的精确性高于经典的频次分布。导出Pearson-Ⅲ分布与指数分布的空间分布型判定指标和抽样量公式,并对赤霉病菌源的分布型和抽样量进行分析,最后指出连续性空间分布型模型的优越性。     

Metabolism of α-aminoisobutyric acid in mungbean hypocotyls in relation to metabolism of 1-aminocyclopropane-1-carboxylic acid

1-Aminocyclopropane-1-carboxylic acid (ACC) is known to be converted to ethylene and conjugated into N-malonyl-ACC in plant tissues. When -amino[1-¹⁴C]isobutyric acid (AIB), a structural analog of ACC, was administered to mungbean (Vigna radiata L.) hypocotyl segments, it was metabolized to ¹⁴CO₂ and conjugated to N-malonyl-AIB (MAIB). -Aminoisobutyric acid inhibited the conversion of ACC to ethylene and also inhibited, to a lesser extent, N-malonylation of ACC and d-amino acids. Although the malonylation of AIB was strongly inhibited by ACC as well as by d-amino acids, the metabolism of AIB to CO₂ was inhibited only by ACC but not by d-amino acids. Inhibitors of ACC conversion to ethylene such as anaerobiosis, 2,4-dinitrophenol and Co²⁺, similarly inhibited the conversion of AIB to CO₂. These results indicate that the malonyalation of AIB to MAIB is intimately related to the malonylation of ACC and d-amino acids, whereas oxidative decarboxylation of AIB is related to the oxidative degradation of ACC to ethylene.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AIB -aminoisobutyric acid - MACC 1-(malonylamino)-cyclopropane-1-carboxylic acid - MAIB -(malonylamino)-isobutyric acid - Mes 2-(N-morpholino)ethanesulfonic acid     

Plasmon-Induced Transparency in a Surface Plasmon Polariton Waveguide with a Right-Angled Slot and Rectangle Cavity

Plasmonics - The phenomenon of plasmon-induced transparency (PIT) is realized a in surface plasmon polariton waveguide at near-infrared frequencies. The right-angled slot and rectangle cavity...     

Association of the variants and haplotypes in the DOCK7, PCSK9 and GALNT2 genes and the risk of hyperlipidaemia

Little is known about the association between the single nucleotide polymorphisms (SNPs) and haplotypes of the dedicator of cytokinesis 7 (DOCK7), pro‐protein convertase subtilisin/kexin type 9 (PCSK9) and polypeptide N‐acetylgalactosaminyltransferase 2 (GALNT2) and serum lipid traits in the Chinese populations. This study was to determine the association between nine SNPs in the three genes and their haplotypes and hypercholesterolaemia (HCH)/hypertriglyceridaemia (HTG), and to identify the possible gene–gene interactions among these SNPs. Genotyping was performed in 733 HCH and 540 HTG participants. The haplotype of C‐C‐G‐C‐T‐G‐C‐C‐G [in the order of DOCK7 rs1168013 (G>C), rs10889332 (C>T); PCSK9 rs615563 (G>A), rs7552841 (C>T), rs11206517 (T>G); and GALNT2 rs1997947 (G>A), rs2760537 (C>T), rs4846913 (C>A) and rs11122316 (G>A) SNPs] was associated with increased risk of HCH and HTG. The haplotypes of C‐C‐G‐C‐T‐G‐C‐C‐A and G‐C‐G‐T‐T‐G‐T‐C‐G were associated with a reduced risk of HCH and HTG. The haplotypes of G‐C‐G‐C‐T‐G‐C‐C‐A and G‐C‐G‐C‐T‐G‐T‐C‐G were associated with increased risk of HCH. The haplotypes of C‐T‐G‐C‐T‐G‐C‐C‐G, G‐C‐A‐C‐T‐G‐C‐C‐G and G‐C‐G‐C‐T‐G‐C‐C‐A were associated with an increased risk of HTG. The haplotypes of G‐C‐G‐C‐T‐G‐T‐C‐A and G‐C‐G‐T‐T‐G‐T‐C‐G were associated with a reduced risk of HTG. In addition, possible inter‐locus interactions among the DOCK7, PCSK9 and GALNT2 SNPs were also noted. However, further functional studies of these genes are still required to clarify which SNPs are functional and how these genes actually affect the serum lipid levels.     

A new silver nanochain SERS analytical platform to detect trace hexametaphosphate with a rhodamine S molecular probe

Using AgNO₃ as the precursor, stable silver nanochain (AgNC) sols, orange‐red in color, were prepared using hydrazine hydrate. A strong surface plasmon resonance Rayleigh scattering (RRS) peak occurred at 420 nm plus two surface plasmon resonance (SPR) absorption peaks at 410 nm and 510 nm. Rhodamine S (RhS) cationic dye was absorbed on the as‐prepared AgNC substrate to obtain a RhS–AgNC surface‐enhanced Raman scattering (SERS) nanoprobe that exhibited a strong SERS peak at 1506 cm^–1 and a strong RRS peak at 375 nm. Upon addition of the analyte sodium hexametaphosphate (HP), it reacted with RhS, which resulted in a decrease in the SERS and RRS peaks that was studied in detail. The decreased SERS and RRS intensities correlated linearly with HP concentration in the range of 0.0125–0.3 µmol/L and 0.05–1.0 µmol/L, with a detection limit of 6 nmol/L and 20 nmol/L HP respectively. Due to advantages of high sensitivity, good selectivity and simple operation, the RhS molecular probes were used to determine HP concentration in real samples. Copyright © 2015 John Wiley & Sons, Ltd.