Low C18 to C20 fatty acid elongase activity and limited conversion of stearidonic acid, 18:4(n–3), to eicosapentaenoic acid, 20:5(n–3), in a cell line from the turbot, Scophthalmus maximus

The TF cell line, derived from a top predatory, carnivorous marine teleost, the turbot (Scophthalmus maximus), is known to have a limited conversion of C₁₈ to C₂₀ polyunsaturated fatty acids (PUFA). To illuminate the underlying processes, we studied the conversions of stearidonic acid, 18:4(n–3), and its elongation product, 20:4(n–3), in TF cells and also in a cell line, AS, derived from Atlantic salmon (Salmo salar), by adding unlabelled (25 μM), U-¹⁴C (1 μM) or deuterated (d5; 25 μM) fatty acids. Stearidonic acid, 18:4(n–3), was metabolised to 20:5(n–3) in both cells lines, but more so in AS than in TF cells. Δ5 desaturation was more active in TF cells than in AS cells, whereas C₁₈ to C₂₀ elongation was much reduced in TF as compared to AS cells. Only small amounts of docosahexaenoic acid (22:6(n–3)) were produced by both cell lines, although there was significant production of 22:5(n–3) in both cultures, especially when 20:4(n–3) was supplemented. We conclude that limited elongation of C₁₈ to C₂₀ fatty acids rather than limited fatty acyl Δ5 desaturation accounts for the limited rate of conversion of 18:3(n–3) to 20:5(n–3) in the turbot cell line, as compared to the Atlantic salmon cell line. The results can account for the known differences in conversions of C₁₈ to C₂₀ PUFA by the turbot and the Atlantic salmon in vivo.     

17β-Estradiol-mediated increase in Cu/Zn superoxide dismutase expression in the brain: a mechanism to protect neurons from ischemia

A number of studies have demonstrated that 17β-estradiol (E(2)) protects the brain from ischemia and yet the mechanism by which this hormone brings about its protective effect is unclear. Interestingly, like E(2), overexpression of the oxidative stress response protein Cu/Zn superoxide dismutase (SOD1), which plays a critical role in regulating reactive oxygen species, also protects the brain from ischemia. Because we previously showed that E(2) treatment of cultured mammary cells increases SOD1 expression, we hypothesized that E(2) might increase SOD1 expression in the brain and that this E(2)-mediated increase in SOD1 expression might help to protect the brain from ischemia. We now show that SOD1 is expressed in cortical neurons, that SOD1 expression is increased by exposure of brain slice cultures to E(2), and that the E(2)-mediated increase in SOD1 expression is further augmented by exposure of brain slice cultures to increased superoxide levels or oxygen and glucose deprivation. Importantly, when cortical neurons are exposed to increased superoxide levels and markers of protein and DNA damage, nitrotyrosine and 8-oxoguanine, respectively, are measured, both protein and DNA damage are reduced. In fact, E(2) reduces nitrotyrosine and 8-oxoguanine levels in brain slice cultures regardless of whether they have or have not been exposed to increased superoxide levels. Likewise, when brain slice cultures are treated with E(2) and deprived of oxygen and glucose, 8-oxoguanine levels are reduced. Taken together, these studies provide a critical link between E(2) treatment, SOD1 expression, and neuroprotection and help to define a mechanism through which E(2)-mediated neuroprotection may be conferred.     

Limitation of C3–CAM shift in the common ice plant under high irradiance

In the halophytic plant Mesembryanthemum crystallinum salinity or drought can change the mode of photosynthesis from C₃ to crassulacean acid metabolism (CAM). These two stress factors are linked to oxidative stress, however, the induction of CAM by oxidative stress per se is not straightforward. Treatment with high light (HL) did not lead to the induction of CAM, as documented by a low night/day difference in malate level and a low expression of the CAM-related form of phosphoenolcarboxylase (Ppc1), despite causing some oxidative damage (elevated MDA level, malondialdehyde). In contrast to the action of high salinity (0.4 M NaCl), HL treatment did not activate neither the cytosolic NADP-malic enzyme nor the chloroplastic form of NADP-dependent malate dehydrogenase (NADP-MDH). In plastids of HL-treated plants a huge amount of starch was accumulated. This was associated with a weak stimulation of hydrolytic and phosphorolytic starch-degrading enzymes, in contrast to their strong up-regulation under high salinity. It is concluded that HL alone is not able to activate starch degradation necessary for CAM performance. Moreover, in the absence of salinity in C₃M. crystallinum plants an age-dependent increase in energy dissipation from PSII was documented under high irradiance, as illustrated by non-photochemical quenching (NPQ). Obtained data suggest that in this halophytic species several photoprotective strategies are strictly salinity-dependent.     

Pyrones from the bark of Garcinia conrauana: Conrauanalactone,a novel C20 derived α-pyrone

Conrauanalactone has been isolated from the bark of Garcinia conrauana Engl. (Guttiferae) and identified, on the basis of spectral and chemical evidence, as 4-hydroxy-6-pentadecyl- 2-pyrone. Minor constituents of the bark have been identified as 5,7-dihydroxychromone and eriodictyol.     

Arabidopsis arenosa (Brassicaceae) from a lead–zinc waste heap in southern Poland – a plant with high tolerance to heavy metals

The morphological traits and tolerance to heavy metals (zinc, cadmium and lead) of two populations of Arabidopsis arenosa (Brassicaceae) were compared. One population was from a zinc–lead waste heap in Bolesław near Olkusz (southern Poland), the other one from the Kampinoski National Park (central Poland). Biometric measurements were done in the field and repeated after cultivation under controlled conditions (garden soil, phytotron chamber). Significant heritable morphological differences between the two populations were found. The plants from the waste-heap are smaller in comparison with the reference population, and their leaves are narrower, thicker with fewer trichomes, indicating. genetic adaptation to xerothermic conditions. The level of tolerance to heavy metals (zinc, cadmium, and lead) was compared by the root test. Very high tolerance to the three metals tested was found in the waste-heap population. Its tolerance exceeded that of four other predominant plant species populations growing on the same waste heap that had previously been tested in our laboratory. We consider the waste-heap population of A. arenosa to be a very suitable ecotype for the study of heavy metal tolerance mechanisms in plants. Responsible Editor: SE: Henk Schat.     

Analysis of new Matrilin-1 gene variants in a case–control study related to dental malocclusions in Equus asinus

Prognathism and brachygnathism are craniofacial deformities that severely affect the health of human and vertebrates, such as donkeys. The multifactorial etiology of this disease makes the genetic analysis a powerful tool for its understanding and prevention of spreading these deformities.     

Oxidative stress potentially enhances FcεRI-mediated leukotriene C4 release dependent on the late-phase increase of intracellular glutathione in mast cells

Cysteinyl leukotrienes (cysLTs), which include leukotriene C₄ (LTC₄), are the predominant class of LTs synthesized by mast cells. CysLTs can induce many of the abnormalities seen in asthma. LTC₄ is generated by the conjugation of LTA₄ with reduced glutathione (GSH) by LTC₄ synthase. During screening of the effects of prostanoids on high-affinity IgE receptor (FcεRI)-mediated LTC₄ release from mast cells, we realized that some prostanoids, including ONO-AE1-259-01 and ONO-AE-248, inhibited LTC₄ release, which was associated with a decrease in the amount of intracellular total GSH. We ascertained that l-buthionine-S,R-sulfoximine (BSO), a selective inhibitor of glutamate-cysteine ligase, inhibited LTC₄ release. In addition, cell-permeable GSH, the glutathione reduced form ethyl ester (GSH-OEt), enhanced LTC₄ release in accordance with the change in intracellular total GSH. Depletion of intracellular total GSH induced by ONO-AE-248 or BSO enhanced FcεRI-mediated LTB₄ release in contrast to LTC₄. Oxidative stress contributes to many pathological conditions including asthma. GSH is a major soluble antioxidant and a cofactor for several detoxifying enzymes including GSH peroxidase. Exposure of mast cells to hydrogen peroxide (H₂O₂) or diamide to mimic oxidative stress unexpectedly increased rather than decreased the intracellular reduced GSH content as well as total GSH in the late phase (i.e., 24 or 48 h after exposure), which was accompanied by an increase in LTC₄ release. In conclusion, FcεRI-mediated LTC₄ release from mast cells is mainly regulated by the amount of intracellular GSH. In some cases, oxidative stress may induce a late-phase increase in intracellular GSH, resulting in enhanced LTC₄ release from mast cells.     

Functional network analysis reveals biological roles of lncRNAs and mRNAs in MOG35–55 specific CD4+T helper cells

Long non-coding RNAs have the potential to regulate immune responses. Their impact on multiple sclerosis has remained elusive. For illustrating their roles in experimental autoimmune encephalomyelitis (EAE) pathogenesis, we investigated the differential expression of lncRNAs and mRNAs in CD4⁺Th cells obtained from myelin oligodendrocytic glycoprotein_35–55(MOG_35–55)-induced EAE and complete Freund's adjuvant (CFA) controls. We observed differential expression of 1112 lncRNAs and 519 mRNAs in CD4⁺Th cells. The functional network showed lncRNAs had the capacity to modulate EAE pathogenesis via regulating many known EAE regulators such as Ptpn6. Predicting the function of lncRNAs demonstrated that dysregulated lncRNAs were closely associated with the development of EAE. These dysregulated lncRNAs may have function in EAE and they could be novel biomarkers and therapeutic targets of EAE. However, the precise mechanisms and biological functions of these specific lncRNAs in EAE pathogenesis require further study.     

Novel M4 positive allosteric modulators derived from questioning the role and impact of a presumed intramolecular hydrogen-bonding motif in β-amino carboxamide-harboring ligands

This letter describes a focused exercise to explore the role of the β-amino carboxamide moiety found in all of the first generation M₄ PAMs and question if the NH₂ group served solely to stabilize an intramolecular hydrogen bond (IMHB) and enforce planarity. To address this issue (and to potentially find a substitute for the β-amino carboxamide that engendered P-gp and contributed to solubility liabilities), we removed the NH₂, generating des-amino congeners and surveyed other functional groups in the β-position. These modifications led to weak M₄ PAMs with poor DMPK properties. Cyclization of the β-amino carboxamide moiety by virtue of a pyrazole ring re-enforced the IMHB, led to potent (and patented) M₄ PAMs, many as potent as the classical bicyclic β-amino carboxamide analogs, but with significant CYP1A2 inhibition. Overall, this exercise indicated that the β-amino carboxamide moiety most likely facilitates an IMHB, and is essential for M₄ PAM activity within classical bicyclic M₄ PAM scaffolds.     

β1a490–508, a 19-Residue Peptide from C-Terminal Tail of Cav1.1 β1a Subunit,Potentiates Voltage-Dependent Calcium Release in Adult Skeletal Muscle Fibers

The α1 and β1a subunits of the skeletal muscle calcium channel, Cav1.1, as well as the Ca²⁺ release channel, ryanodine receptor (RyR1), are essential for excitation-contraction coupling. RyR1 channel activity is modulated by the β1a subunit and this effect can be mimicked by a peptide (β1a490–524) corresponding to the 35-residue C-terminal tail of the β1a subunit. Protein-protein interaction assays confirmed a high-affinity interaction between the C-terminal tail of the β1a and RyR1. Based on previous results using overlapping peptides tested on isolated RyR1, we hypothesized that a 19-amino-acid residue peptide (β1a490–508) is sufficient to reproduce activating effects of β1a490–524. Here we examined the effects of β1a490–508 on Ca²⁺ release and Ca²⁺ currents in adult skeletal muscle fibers subjected to voltage-clamp and on RyR1 channel activity after incorporating sarcoplasmic reticulum vesicles into lipid bilayers. β1a490–508 (25 nM) increased the peak Ca²⁺ release flux by 49% in muscle fibers. Considerably fewer activating effects were observed using 6.25, 100, and 400 nM of β1a490–508 in fibers. β1a490–508 also increased RyR1 channel activity in bilayers and Cav1.1 currents in fibers. A scrambled form of β1a490–508 peptide was used as negative control and produced negligible effects on Ca²⁺ release flux and RyR1 activity. Our results show that the β1a490–508 peptide contains molecular components sufficient to modulate excitation-contraction coupling in adult muscle fibers.     

Synthesis, X-ray crystal structure and properties of a novel tetranuclear unsymmetrical (μ-SO4) copper(II) complex: relevance to SO2 fixation

The synthesis, by fixation of SO₂, the unusual crystal structure, and the spectral and redox properties of the new compound [Cu₄(TPPNOL)₂(μ-SO₄)₂](ClO₄)₂ (1) [HTPPNOL (N,N,N′-tris-(2-pyridylmethyl)-1,3-diaminopropan-2-ol)] are reported. In 1, the copper(II) ions are bridged by the alkoxo oxygen atoms of the HTPPNOL ligand and by exogenous sulfate bridges. The structure of 1 consists of a centro-symmetric tetranuclear core or a “Dimer of Dimers” complex, in which a μ-O,O′ sulfate oxygen atom is further coordinated to the copper centre of another similar dinuclear unit through a μ-O,O, sulfate bridge resulting in a tetranuclear arrangement. Thus, the dinuclear units are linked by two μ-O,O sulfate bridges. The simultaneous presence of two distinct coordination modes for the sulfate group in this structure is rare and 1 represents the first coordination compound presenting μ-O,O′ and μ-O,O type structures. The SO₂ fixation was monitored by changes in the electronic spectra which indicated the formation of the intermediate hydroxo complex [Cu₂(TPPNOL)(OH)₂]⁺, in basic medium, which, we propose, acts as the nucleophile in the SO₂ fixation mechanism.     

A novel TNNI2 mutation causes Freeman–Sheldon syndrome in a Chinese family with an affected adult with only facial contractures

Distal arthrogryposes (DAs), a clinically and genetically heterogeneous group of disorders characterized by congenital contractures with predominant involvement of the hands and feet, can be classified into at least 12 different forms. These autosomal dominant disorders are of variable expressivity and reduced penetrance. Mutations in sarcomeric protein genes, including troponin I2 (TNNI2), troponin T3 (TNNT3), tropomyosin 2 (TPM2), embryonic myosin heavy chain 3 (MYH3), and myosin binding protein C1 (MYBPC1), have been identified in distal arthrogryposis type 1 (DA1, MIM 108120), type 2B (DA2B, MIM 601680) and type 2A (DA2A)/Freeman–Sheldon syndrome (FSS, MIM 193700). However, mutations causing FSS have only been reported in MYH3. Herein we describe a Chinese DA family whose members meet classical strict criteria for FSS, as well as one member of the family who has isolated facial features consistent with FSS. No disease-causing mutation was found in MYH3. Segregation of microsatellite markers flanking the TNNI2 and TNNT3 genes at 11p15.5 was compatible with linkage. Subsequent sequencing of TNNI2 revealed a novel mutation, c.A493T (p.I165F), located in the C-terminal region, which is critical for proper protein function. This mutation was found to cosegregate with the FSS phenotype in this family, and assessment using SIFT and PolyPhen-2 predicted a damaging effect. To the best of our knowledge, we report the first TNNI2 mutation in classical FSS and describe an atypical adult FSS case with only facial contractures resulting from somatic mosaicism. We infer that DA1, DA2B and FSS represent a phenotypic continuum of the same disorder and provide further genetic evidence for this hypothesis.     

Identification of the Intermediate Charge-Separated State PβL in a Leucine M214 to Histidine Mutant of the Rhodobacter sphaeroides Reaction Center Using Femtosecond Midinfrared Spectroscopy

Energy and electron transfer in a Leu M214 to His (LM214H) mutant of the Rhodobacter sphaeroides reaction center (RC) were investigated by applying time-resolved visible pump/midinfrared probe spectroscopy at room temperature. This mutant replacement of the Leu at position M214 resulted in the incorporation of a bacteriochlorophyll (BChl) in place of the native bacteriopheophytin in the L-branch of cofactors (denoted β_L). Purified LM214H RCs were excited at 600 nm (unselective excitation), at 800 nm (direct excitation of the monomeric BChl cofactors B_L and B_M), and at 860 nm (direct excitation of the primary donor (P) BChl pair (P_L/P_M)). Absorption changes associated with carbonyl (C=O) stretch vibrational modes (9-keto, 10a-ester, and 2a-acetyl) of the cofactors and of the protein were recorded in the region between 1600 cm⁻¹ and 1770 cm⁻¹, and the data were subjected to both a sequential analysis and a simultaneous target analysis. After photoexcitation of the LM214H RC, P^∗ decayed on a timescale of ∼6.3 ps to P⁺B_L⁻. The decay of P⁺B_L⁻ occurred with a lifetime of ∼2 ps, ∼3 times slower than that observed in wild-type and R-26 RCs (∼0.7 ps). Further electron transfer to the β_L BChl resulted in formation of the P⁺β_L⁻ state, and its infrared absorbance difference spectrum is reported for the first time, to our knowledge. The fs midinfrared spectra of P⁺B_L⁻ and P⁺β_L⁻ showed clear differences related to the different environments of the two BChls in the mutant RC.     

Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt2(μ-S)2(PPh3)4] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes

The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with α,ω-dibromoalkanes Br(CH₂)_nBr (n = 4, 5, 6, 8, 12) gave mono-alkylated [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)_nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)₁₂}]²⁺ was accessible from the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)₁₂Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at −18 °C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂(μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to ω-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S}(PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)_n−2CHCH₂}(PPh₃)_m]⁺ (m = 2 or 3; m ≠ 4), most significant for n = 4, formed by elimination of HBr.