Manganese(II) complexes of an acyclic phenol-based dinucleating ligand with four methoxyethyl chelating arms: synthesis, structure, magnetism and electrochemistry

Dinuclear manganese(II) complexes [Mn₂(bomp)(PhCO₂)₂]BPh₄ (1), [Mn₂(bomp)(MeCO₂)₂]BPh₄ (2), and [Mn₂(bomp)(PhCO₂)₂]PF₆ (3) were synthesized with a dinucleating ligand 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-methylphenol [H(bomp)]. Dinuclear zinc complex [Zn₂(bomp)(PhCO₂)₂]PF₆ (4) was also synthesized for the purpose of comparison. X-ray analysis revealed that the complex 1·CHCl₃ contains two manganese ions bridged by the phenolic oxygen and two benzoate groups, forming a μ-phenoxo-bis(μ-benzoato)dimanganese(II) core. Magnetic susceptibility measurements of 1–3 over the temperature range 1.8–300 K indicated antiferromagnetic interaction (J=−4 to −6 cm⁻¹). Cyclic voltammograms of 3 showed a quasi-reversible oxidation process at +0.9 V versus a saturated sodium chloride calomel reference electrode, assigned to Mn^IIMn^II/Mn^IIMn^III.     

A Food-Derived Flavonoid Luteolin Protects against Angiotensin II-Induced Cardiac Remodeling

Oxidative stress has been implicated in cardiac remodeling (cardiac fibrosis and hypertrophy), which impairs cardiac function and metabolism; therefore, it is anticipated antioxidative compounds will have protective properties against cardiac remodeling. Luteolin (3’,4’,5,7-tetrahydroxyflavone), a widely distributed flavonoid found in many herbal extracts including celery, green pepper, perilla leaves and seeds, and chamomile, is a known to be a potent antioxidant and was previously demonstrated to exert an antifibrotic effect in the lungs and the liver. In this study, we clearly demonstrate that oral pretreatment with the higher-luteolin diet (0.035% (wt/wt)) protected against cardiac fibrosis and hypertrophy as well as a hyperoxidative state in Ang II-infused rats. In cardiac tissue, increased gene expression levels of TGFβ1, CTGF, Nox2, Nox4, ANP, and BNP induced by Ang II were restored by oral pretreatment of this high-luteolin diet. In cultured rat cardiac fibroblasts, H₂O₂-induced TGFβ1 expression and the phosphorylation of JNK were suppressed by luteolin pretreatment. In conclusion, food-derived luteolin has protective actions against Ang II-induced cardiac remodeling, which could be mediated through attenuation of oxidative stress.     

Amino-acid sequence of ribonuclease T2 from Aspergillus oryzae

The amino acid sequence of ribonuclease T2 (RNase T2) from Aspergillus oryzae has been determined. This has been achieved by analyzing peptides obtained by digestions with Achromobacter lyticus protease I, Staphylococcus aureus V8 protease, and alpha-chymotrypsin of two large cyanogen bromide peptides derived from the reduced and S-carboxymethylated or S-aminoethylated protein. Digestion with A. lyticus protease I was successfully used to degrade the N-terminal half of the S-aminoethylated protein at cysteine residues. RNase T2 is a glycoprotein consisting of 239 amino acid residues with a relative molecular mass of 29,155. The sugar content is 7.9% (by mass). Three glycosylation sites were determined at Asns 15, 76 and 239. Apparently RNase T2 has a very low degree of sequence similarity with RNase T1, but a considerable similarity is observed around the amino acid residues involved in substrate recognition and binding in RNase T1. These similar residues may be important for the catalytic activity of RNase T2.     

Incorporation of fatty acids by Streptococcus mutans

In a series of investigations into the cariogenicity of Streptococcus mutans, we studied the incorporation of exogenous fatty acids with reference to glucosyltransferase secretion and membrane fatty acid changes. When cells were grown with different fatty acids, both saturated and unsaturated fatty acids were readily incorporated into the membrane lipids and were biotransformed and elongated preferentially to the longer 16- and 18-carbon-chain fatty acids. This incorporation and chain-elongation led to significant changes in fatty acids composition. By adding fatty acids to the medium, it was possible to appropriately modify the degree of unsaturation and the relative ratio between specific fatty acids in the membrane lipids of S. mutans.     

An RNA chaperone,AtCSP2, negatively regulates salt stress tolerance

Cold shock domain (CSD) proteins are RNA chaperones that destabilize RNA secondary structures. Arabidopsis Cold Shock Domain Protein 2 (AtCSP2), one of the 4 CSD proteins (AtCSP1-AtCSP4) in Arabidopsis, is induced during cold acclimation but negatively regulates freezing tolerance. Here, we analyzed the function of AtCSP2 in salt stress tolerance. A double mutant, with reduced AtCSP2 and no AtCSP4 expression (atcsp2–3 atcsp4–1), displayed higher survival rates after salt stress. In addition, overexpression of AtCSP2 resulted in reduced salt stress tolerance. These data demonstrate that AtCSP2 acts as a negative regulator of salt stress tolerance in Arabidopsis.     

Wheat SOC1 functions independently of WAP1/VRN1, an integrator of vernalization and photoperiod flowering promotion pathways

Heading time in bread wheat ( Triticum aestivum L.) is determined by three characters – vernalization requirement, photoperiodic sensitivity and narrow-sense earliness (earliness per se) – which are involved in the phase transition from vegetative to reproductive growth. The wheat APETALA1 ( AP1 )-like MADS-box gene, wheat AP1 ( WAP1 , identical with VRN1 ), has been identified as an integrator of vernalization and photoperiod flowering promotion pathways. A MADS-box gene, SUPPRESSOR OF OVEREXPRESSION OF CO 1 ( SOC1 ) is an integrator of flowering pathways in Arabidopsis . In this study, we isolated a wheat ortholog of SOC1 , wheat SOC1 ( WSOC1 ), and investigated its relationship to WAP1 in the flowering pathway. WSOC1 is expressed in young spikes but preferentially expressed in leaves. Expression starts before the phase transition and is maintained during the reproductive growth phase. Overexpression of WSOC1 in transgenic Arabidopsis plants caused early flowering under short-day conditions, suggesting that WSOC1 functions as a flowering activator in Arabidopsis . WSOC1 expression is affected neither by vernalization nor photoperiod, whereas it is induced by gibberellin at the seedling stage. Furthermore, WSOC1 is expressed in transgenic wheat plants in which WAP1 expression is cosuppressed. These findings indicate that WSOC1 acts in a pathway different from the WAP1 -related vernalization and photoperiod pathways.     

A cold inducible multidomain cystatin from winter wheat inhibits growth of the snow mold fungus, Microdochium nivale

A novel cold-induced cystatin cDNA clone (TaMDC1) was isolated from cold acclimated winter wheat crown tissue by using a macroarray-based differential screening method. The deduced amino acid sequence consisted of a putative N-terminal secretory signal peptide of 37 amino acids and a mature protein (mTaMDC1) with a molecular mass of 23 kDa. The mTaMDC1 had a highly conserved N-terminal cystatin domain and a long C-terminal extension containing a second region, which exhibited partial similarity to the cystatin domain. The recombinant mTaMDC1 was purified from Escherichia coli and its cysteine proteinase inhibitory activity against papain was analyzed. The calculated Ki value of 5.8×10⁻⁷ M is comparable to those reported for other phytocystatins. Northern and western blot analyses showed elevated expression of TaMDC1 mRNA and protein during cold acclimation of wheat. In addition to cold, accumulation of the TaMDC1 message was induced by other abiotic stresses including drought, salt and ABA treatment. Investigation of in vitro antifungal activity of mTaMDC1 showed strong inhibition on the mycelium growth of the snow mold fungus Microdochium nivale. Hyphae growth was totally inhibited in the presence of 50 μg/ml mTaMDC1 and morphological changes such as swelling, fragmentation and sporulation of the fungus were observed. The mechanisms of the in vitro antifungal effects and the possible involvement of TaMDC1 in cold induced snow mold resistance of winter wheat are discussed.     

Racemization in the Coupling Reaction with the Several Methods beside the Activated Ester Methods

The degree of racemization in the coupling reaction, Pro-Val + Pro, with the several other methods than the activated ester methods was measured and the results were compared with that in the coupling reaction, Leu-Phe + Val, as well as in the previous paper.¹⁾ In the azide and the mixed anhydride methods, no or almost no racemization was detected, whereas in the other tested methods of peptide synthesis (Pachornik-, DCCD- and phosphazo-methods) the significantly large racemization was observed. It can be attributed to the strong nucleo- philic N-atom in the penultimate amino acids (Pro) and the steric hindrance of C-terminal amino acid (Val), which are favourable to the formation of the oxazolone ring.

This assumption was further systematically confirmed in the synthesis of the other several tripeptides with the DCCD method. The separation of the diastereoisomers (LLL and LDL) of the resulting tripeptides by gas chromatography with a packed column was also here reported.     

Angiotensin II and tumor necrosis factor-alpha synergistically promote monocyte chemoattractant protein-1 expression: roles of NF-kappaB, p38, and reactive oxygen species

We examined whether ANG II and TNF-alpha cooperatively induce vascular inflammation using the expression of monocyte chemoattractant protein (MCP)-1 as a marker of vascular inflammation. ANG II and TNF-alpha stimulated MCP-1 expression in a synergistic manner in vascular smooth muscle cells. ANG II-induced MCP-1 expression was potently inhibited to a nonstimulated basal level by blockade of the p38-dependent pathway but only partially inhibited by blockade of the NF-kappaB-dependent pathway. In contrast, TNF-alpha-induced MCP-1 expression was potently suppressed by blockade of NF-kappaB activation but only modestly suppressed by blockade of p38 activation. ANG II- and TNF-alpha-induced activation of NF-kappaB- and p38-dependent pathways was partially inhibited by pharmacological inhibitors of ROS production. Furthermore, ANG II- and TNF-alpha-stimulated MCP-1 expression was partially suppressed by ROS inhibitors. We also examined whether endogenous ANG II and TNF-alpha cooperatively promote vascular inflammation in vivo using a wire injury model of the rat femoral artery. Blockade of both ANG II and TNF-alpha further suppressed neointimal formation, macrophage infiltration, and MCP-1 expression in an additive manner compared with blockade of ANG II or TNF-alpha alone. These results suggested that ANG II and TNF-alpha synergistically stimulate MCP-1 expression via the utilization of distinct intracellular signaling pathways (p38- and NFkappaB-dependent pathways) and that these pathways are activated in ROS-dependent and -independent manners. These results also suggest that ANG II and TNF-alpha cooperatively stimulate vascular inflammation in vivo as well as in vitro.     

Morphine-Induced Changes in Histamine Dynamics in Mouse Brain

The effect of the acute morphine treatment on histamine (HA) pools in the brain and the spinal cord was examined in mice. Morphine (1-50 mg/kg, s.c.) administered alone caused no significant change in the steady-state levels of HA and its major metabolite, tele-methylhistamine (t-MH), in the brain. However, depending on the doses tested, morphine significantly enhanced the pargyline (65 mg/kg, i.p.)-induced accumulation of t-MH and this effect was antagonized by naloxone. A specific inhibitor of histidine decarboxylase, alpha-fluoromethylhistidine (alpha-FMH) (50 mg/kg, i.p.), decreased the brain HA level in consequence of the almost complete depletion of the HA pool with a rapid turnover. Morphine further decreased the brain HA level in alpha-FMH-pretreated mice. Morphine administered alone significantly reduced the HA level in the spinal cord, an area where the turnover of HA is very slow. These results suggest that the acute morphine treatment increases the turnover of neuronal HA via opioid receptors, and this opiate also releases HA from a slowly turning over pool(s).