Studies on Some Properties of the Apoplastic β-N-Acetyl-D-Hexosaminidase from Tomato Leaves

Some properties of the β-N-acetyl-D-hexosaminidase purified from intercellular fluid of tomato leaves after the plant was systematically infected by TMV (tobacco mosaic virus) were studied. When pNP β-D-GlcNAc (p nitrophenyl-N-aeetyl β-D-glucosaminide) or pNP β-D- GalNAc (p-nitrophenyl-N-acetyl-β-D galactosaminide) was used as the substrate, it showed the optical pH between 4. 8--5.0 and optical temperature between 44— 47℃. Studies of thermostabillty indicated that the enzyme had a biphasic denaturation curve. Using pNP-β-D-GIcNAc or pNP-β-D GalNAc as the substrate, the Km value of the enzyme was 0. 36 and 0. 67 mmol/L respectively. N acetyi-D glucosamine and N acetyl-D-galactosamine were competitive inhibitors of the enzyme activities. Ag+ and Hg2+ were sensitive inhibitors and Fe2+ . Fe3+ and Cu2+ were also inhibitors enzyme activities.     

Production of ascorbic acid,total protein,callus and root in vitro of non-heading Chinese cabbage by tissue culture

Molecular Biology Reports - The objective of the present work was the selection of cultivar, suitable medium and explant type for callus, root production, ascorbic acid, total ascorbic acid,...     

Identification and validation of quantitative trait loci conferring tan spot resistance in the bread wheat variety Ernie

Tan spot, caused by Pyrenophora tritici-repentis, is a foliar disease of wheat, and it can inflict serious reduction in grain yield and quality. The bread wheat variety Ernie was found to be immune to this disease in Australia, and its genetic control was investigated by quantitative trait loci (QTL) analysis using a doubled haploid population. Eight QTL were identified in this population from three independent trials, and four of them were derived from the parent Ernie. The most significant QTL was located on chromosome arm 2BS, explaining 38.2, 29.8 and 36.2% of the phenotypic variance, respectively, in these trials. The effects of the 2BS QTL were further validated in four additional populations. The presence of this single QTL reduced disease severity by between 29.2 and 67.1% with an average of 50.5%. The significant effects of this QTL and its consistent detection across all the trials with different genetic backgrounds make it an ideal target for breeding programmes as well as for its further characterization. Data from this study also showed that neither plant height nor heading date significantly affects tan spot resistance.     

Anti-IL-33 antibody treatment inhibits airway inflammation in a murine model of allergic asthma

Interleukin (IL)-33 is a recently described member of the IL-1 family and has been shown to induce production of T helper type 2 cytokines. In this study, an anti-IL-33 antibody was evaluated against pulmonary inflammation in mice sensitized and challenged with ovalbumin. The anti-IL-33 or a control antibody (150 μg/mouse) was given intraperitoneally as five doses before the sensitization and antigen challenge. Treatment with anti-IL-33 significantly reduced serum IgE secretion, the numbers of eosinophils and lymphocytes, and concentrations of IL-4, IL-5, and IL-13 in bronchoalveolar lavage fluid compared with administration of a control antibody. Histological examination of lung tissue demonstrated that anti-IL-33 significantly inhibited allergen-induced lung eosinophilic inflammation and mucus hypersecretion. Our data demonstrate for the first time that anti-IL-33 antibody can prevent the development of asthma in a mouse model and indicate that blockade of IL-33 may be a new therapeutic strategy for allergic asthma.     

IGF-1 Reduces BACE-1 Expression in PC12 Cells via Activation of PI3-K/Akt and MAPK/ERK1/2 Signaling Pathways

Insulin-like growth factor 1 (IGF-1) stimulates α-secretase processing of amyloid precursor protein (APP) and decreases Aβ production. Little is known about the relationship between IGF-1 and β-site amyloid precursor protein cleaving enzyme 1 (BACE-1), the protease essential for the production of β-amyloid peptides (Aβ). Here, we investigated the effect of IGF-1 on BACE-1 in PC12 cells. Quantitative polymerase chain reaction analysis and western blot showed that treatment of cells with IGF-1 significantly decreased the levels of BACE-1 mRNA and protein. Furthermore, IGF-1 increased the phosphorylation of Akt and ERK1/2. The presence of the phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002 and the mitogen-activated protein kinase kinases (MEK) inhibitor PD98059 blocked the effect of IGF-1 on BACE-1. Our data indicated that IGF-1-induced reduction of BACE-1 might involve the PI3-K/Akt and MAPK/ERK1/2 signaling pathways.     

Synthesis, structural and electrochemical features of alicyclic and aromatic α,α′-N2- and-S2-dioximate macrobicyclic cobalt(II,III) and ruthenium(II) tris-complexes

The triribbed-functionalized cobalt(II,III) and ruthenium(II) clathrochelate derivatives of the vic-dioximes with two nitrogen or sulfur atoms in α-positions to π-conjugated diazomethine chelate fragments of a macrobicyclic framework were obtained in moderate yields under mild and high dilution conditions by nucleophilic substitution of six reactive chlorine atoms of the boron-capped macrobicyclic cobalt and ruthenium(II) precursors with N₂- and S₂-dinucleophiles (ethylenediamine and the corresponding α-dithiols in the presence of triethylamine, respectively). The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, ¹H and ¹³C{¹H} NMR and EPR spectroscopies, magnetochemistry and X-ray crystallography. The MN₆-coordination polyhedra of all the X-ray studied clathrochelates possess a slightly distorted trigonal prismatic geometry. The encapsulated cobalt(II) ions are shifted from the centers of the cavities formed by the macrobicyclic ligand due to the Jahn-Teller distortion, while the ruthenium and iron(II) ions in their clathrochelate analogs do occupy these centers. The main geometrical parameters of the macrobicyclic frameworks vary with Shannon radius of an encapsulated metal ion. In the case of the tris-ethylenediamine cobalt(III) clathrochelate, the field strength of the macrobicyclic amine ligand is essentially lower than those for their aromatic and aliphatic analogs because of the negative σ_para-effect of the ribbed alkylamine substituents. The magnetometry and EPR data confirmed the low-spin character of the cobalt(II) complexes synthesized. The electrochemically generated oxidized cobalt clathrochelates are stable in the CVA time scale, whereas their ruthenium- and iron-containing analogs as well as the reduced forms of all the cobalt, ruthenium and iron complexes obtained are unstable.     

Increased abundance of the non-indigenous zooplanktivore, <Emphasis Type=Italic>Bythotrephes longimanus</Emphasis>, is strongly correlated with greater spring prey availability in Canadian Shield lakes

The non-indigenous zooplanktivore, Bythotrephes longimanus, is a large Palaearctic cladoceran that is spreading rapidly in the Great Lakes watershed in North America. As a voracious predator, Bythotrephes can reduce herbivorous cladoceran abundance and diversity; however, the variables that affect its abundance are not well understood. To determine what bottom-up factors are associated with the abundance and seasonal dynamics of established Bythotrephes populations, two Bythotrephes datasets from lakes in south-central Ontario, Canada, were analysed using multiple regression and multivariate analyses: a multi-lake dataset of nine lakes sampled in 2003 and a multi-year dataset of one of these lakes, Harp Lake, sampled from 1994–1998 and 2001–2004. Bottom-up variables tested were Secchi disk depth, epilimnetic temperature, cladoceran (prey) density, total phosphorus, dissolved organic carbon and Chlorophyll a, as well as maximum depth for the multi-lake dataset. In both analyses and datasets, springtime abundance of herbivorous cladocerans was consistently found to be a significant factor associated with Bythotrephes (June–September) abundance; Bythotrephes annual abundance was significantly and positively associated with mean May and June prey abundance, along with mean Secchi disk depth for the multi-lake dataset, and groups of lakes or years with similar Bythotrephes seasonal abundance patterns were predicted by June prey abundance. Additionally, prey availability was the dominant contributor towards changes in weekly Bythotrephes birth rates calculated for two of the study lakes. Our study suggests that prey availability influences Bythotrephes abundance, which provides evidence that Bythotrephes establishment success is affected by the abundance of its prey.     

The effect of calciums on molecular motions of proteinase K

The native serine protease proteinase K binds two calcium cations. It has been reported that Ca²⁺ removal decreased the enzyme’s thermal stability and to some extent the substrate affinity, but has discrepant effects on catalytic activity of the enzyme. Molecular dynamics simulations were performed on the Ca²⁺-bound and Ca²⁺-free proteases to investigate the mechanism by which the calciums affect the structural stability, molecular motions, and catalytic activity of proteinase K. Very similar structural properties were observed between these two forms of proteinase K during simulations; and several long-lived hydrogen bonds and salt bridges common to both forms of proteinase K were found to be crucial in maintaining the local conformations around these two Ca²⁺ sites. Although Ca²⁺ removal enhanced the overall flexibility of proteinase K, the flexibility in a limited number of segments surrounding the substrate-binding pockets decreased. The largest differences in the equilibrium structures of the two simulations indicate that, upon the removal of Ca²⁺, the large concerted motion originating from the Ca1 site can transmit to the substrate-binding regions but not to the catalytic triad residues. In conjunction with the large overlap of the essential subspaces between the two simulations, these results not only provide insight into the dynamics of the underlying molecular mechanism responsible for the unchanged enzymatic activity as well as the decreased thermal stability and substrate affinity of proteinase K upon Ca²⁺ removal, but also complement the experimentally determined structural and biochemical data.     

中国新归化种广布苋的分布及其与腋花苋的关系

本文报道了中国苋科苋属的一新记录归化植物——广布苋(Amaranthus graecizans L．)。该种植株常匍匐,叶片狭长椭圆形至线状披针形,有时线形或菱形卵形,长至少为宽的2.5倍,花被片3枚,近等长,与中国有分布的本属其他物种有所区别。该种原产于欧洲地中海地区、非洲北部至亚洲西部,归化于欧洲其他地区、东亚、澳大利亚、北美洲以及我国的河南、河北和山东等地区。该种易与苋属其他种类相混淆,因此其在我国的分布区可能被低估。此外,本文还对该种的种下等级以及该种的相似种进行了区分,并对该种下亚种Amaranthus graecizans subsp. thellungianus (Nevski) Gusev与国内文献记载的腋花苋(Amaranthus roxburghianus Kung)之间的关系作了说明与澄清。