Quantitative and time-course analysis of microbial degradation of 1H,1H,2H,2H,8H,8H–perfluorododecanol in activated sludge

A methylene group in the fluorinated carbon backbone of 1H,1H,2H,2H,8H,8H–perfluorododecanol (degradable telomer fluoroalcohol, DTFA) renders the molecule cleavable by microbial degradation into two fluorinated carboxylic acids. Several biodegradation products of DTFA are known, but their rates of conversion and fates in the environment have not been determined. We used liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) to quantitatively investigate DTFA biodegradation by the microbial community in activated sludge in polyethylene terephthalate (PET) flasks, which we also determined here showed least adsorption of DTFA. A reduction in DTFA concentration in the medium was accompanied by rapid increases in the concentrations of 2H,2H,8H,8H–perfluorododecanoic acid (2H,2H,8H,8H–PFDoA), 2H,8H,8H-2-perfluorododecenoic acid (2H,8H,8H-2-PFUDoA), and 2H,2H,8H-7-perfluorododecenoic acid and 2H,2H,8H-8-perfluorododecenoic acid (2H,2H,8H-7-PFUDoA/2H,2H,8H-8-PFUDoA), which were in turn followed by an increase in 6H,6H–perfluorodecanoic acid (6H,6H–PFDeA) concentration, and decreases in 2H,2H,8H,8H–PFDoA, 2H,8H,8H-2-PFUDoA, and 2H,2H,8H-7-PFUDoA/2H,2H,8H-8-PFUDoA concentrations. Accumulation of perfluorobutanoic acid (PFBA), a presumed end product of DTFA degradation, was also detected. Our quantitative and time-course study of the concentrations of these compounds reveals main routes of DTFA biodegradation, and the presence of new biodegradation pathways.

     

Antitubercular activity of α,ω-diaminoalkanes,H2N(CH2)nNH2

A series of 11 α,ω-diaminoalkanes, (H₂N(CH₂)_nNH₂, n = 2–12) have been evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Compounds, (H₂N(CH₂)_nNH₂, n = 9–12), exhibited a very good activities in the range 2.50–3.12 μg/mL, which can be compared with that of the first line drug, ethambutol (3.12 μg/mL). These results and a preliminary QSAR study can be considered an important start point for the rational design of new leads for anti-TB compounds.     

Analysis of [2H7]methionine, [2H4]methionine,methionine, [2H4]homocysteine and homocysteine in plasma by gas chromatography–mass spectrometry to follow the fate of administered [2H7]methionine

Homocysteine plays a key role in several pathophysiological conditions. To assess the methionine–homocysteine kinetics by stable isotope methodology, we developed a simultaneous quantification method of [²H₇]methionine, [²H₄]methionine, methionine, [²H₄]homocysteine and homocysteine in rat plasma by gas chromatography–mass spectrometry (GC–MS). [¹³C]Methionine and [¹³C]homocysteine were used as analytical internal standards to account for losses associated with the extraction, derivatization and chromatography. For labeled and non-labeled homocysteine measurements, disulfide bonds between homocysteine and other thiols or proteins were reduced by dithiothreitol. The reduced homocysteine and methionine species were purified by cation-exchange chromatography and derivatized with isobutyl chlorocarbonate in water–ethanol–pyridine. Quantification was carried out by selected ion monitoring of the molecular-related ions of N(O,S)-isobutyloxycarbonyl ethyl ester derivatives on the chemical ionization mode. The intra- and inter-day precision of the assay was less than 6% for all labeled and non-labeled methionine and homocysteine species. The method is sensitive enough to determine pharmacokinetics of labeled methionine and homocysteine.     

B30H8, B39H9 2−, B42H10, B48H10, and B72H12: polycyclic aromatic snub hydroboron clusters analogous to polycyclic aromatic hydrocarbons

Calculations performed at the ab initio level using the recently reported planar concentric π-aromatic B₁₈H₆ ²⁺(1) [Chen Q et al. (2011) Phys Chem Chem Phys 13:20620] as a building block suggest the possible existence of a new class of B_3n H _m polycyclic aromatic hydroboron (PAHB) clusters—B₃₀H₈(2), B₃₉H₉ ^2?(3), B₄₂H₁₀(4/5), B₄₈H₁₀(6), and B₇₂H₁₂(7)—which appear to be the inorganic analogs of the corresponding C _n H _m polycyclic aromatic hydrocarbon (PAHC) molecules naphthalene C₁₀H₈, phenalenyl anion C₁₃H₉ ^?, phenanthrene/anthracene C₁₄H₁₀, pyrene C₁₆H₁₀, and coronene C₂₄H₁₂, respectively, in a universal atomic ratio of B:C?=?3:1. Detailed canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), and electron localization function (ELF) analyses indicate that, as they are hydrogenated fragments of a boron snub sheet [Zope RR, Baruah T (2010) Chem Phys Lett 501:193], these PAHB clusters are aromatic in nature, and exhibit the formation of islands of both σ- and π-aromaticity. The predicted ionization potentials of PAHB neutrals and electron detachment energies of small PAHB monoanions should permit them to be characterized experimentally in the future. The results obtained in this work expand the domain of planar boron-based clusters to a region well beyond B₂₀, and experimental syntheses of these snub B_3n H _m clusters through partial hydrogenation of the corresponding bare B_3n may open up a new area of boron chemistry parallel to that of PAHCs in carbon chemistry.

Origin, functions and chemistry of H‐2 regulated odorants

Genes located within the major histocompatibility complex (MHC) of mice are responsible for individual differences in body odor (odortypes). In this review we suggest that the MHC genes themselves are responsible for odor differences among MHC‐congenic mice. Recent studies indicating that volatile carboxylic acids are at least in part responsible for the individual odors and what this finding implies about the pathway from gene to odorant are also reviewed. We suggest that odorants or their precursors are bound directly by MHC products and are released into serum and concentrated in urine. Finally, possible functions of MHC odortypes in mice are enumerated and important future research questions are raised. This revised version was published online in July 2006 with corrections to the Cover Date.     

A novel vanadium(V) homocitrate complex: synthesis,structure, and biological relevance of [K2(H2O)5][(VO2)2(R,S-homocitrate)2]·H2O

Initial investigations into the possible roles of homocitric acid in the biosynthesis and function of the active site cofactor of nitrogenase resulted in the isolation and characterization of the dinuclear vanadium(V) species [K₂(H₂O)₅][(VO₂)₂(R,S-C₇H₈O₇)₂]·H₂O ( 1). Complex 1 represents the first synthetic structurally characterized transition metal homocitrate complex and may represent an early mobilized precursor in the biosynthesis of VFeco. Compound 1 was characterized by a variety of physical methods, including X-ray crystallography. Crystal data: space group P?* (#2), with a?=?10.292 (3)?Å, b?=?16.663 (3)?Å, c?=?8.343 (1)?Å, α?=?95.93 (1)°, β?=?105.74 (2)°, γ?=?90.86 (2)°, V?=?1386 (1)?ų, and Z?=?2. The homocitrate ligand is coordinated to the vanadium(V) atoms in a bidentate fashion via the deprotonated bridging hydroxyl group and a carboxylate donor. This unique coordination mode accurately mimics the coordination of homocitrate to the cofactor of nitrogenase.     

A B3LYP and MP2(full) theoretical investigation into the cooperativity effect between dihydrogen-bonding and H–M∙∙∙π (M = Li, Na, K) interactions among HF, MH with the π-electron donor C2H2, C2H4 or C6H6

The DFT-B3LYP/6-311++G(3df,2p) and MP2(full)/6-311++G(3df,2p) calculations were carried out on the binary complex formed by HM (M?=?Li, Na, K) and HF or the π-electron donor (C₂H₂, C₂H₄, C₆H₆), as well as the ternary system FH???HM???C₂H₂/C₂H₄/C₆H₆. The cooperativity effect between the dihydrogen-bonding and H–M???π interactions was investigated. The result shows that the equilibrium distances R _H???H and R _M???π in the ternary complex decrease and both the H???H and H–M???π interactions are strengthened when compared to the corresponding binary complex. The cooperativity effect of the dihydrogen bond on the H–M???π interaction is more pronounced than that of the M???π bond on the H???H interaction. Furthermore, the values of cooperativity effect follow the order of FH???HNa???π?>?FH???HLi???π?>?FH???HK???π and FH???HM???C₆H₆?>?FH???HM???C₂H₄?>?FH???HM???C₂H₂. The nature of the cooperativity effect was revealed by the analyses of the charge of the hydrogen atoms in H???H moiety, atom in molecule (AIM) and electron density shifts methods.

How relevant are S=O and P=O Double Bonds for the Description of the Acid Molecules H2SO3, H2SO4, and H3PO4, respectively?

The acid molecules H₂SO₃, H₂SO₄, and H₃PO₄ are usually drawn using "Lewis structures" which exhibit the octet extension by 3d-orbitals on sulfur and phosphorus, respectively. Thus, S=O and P=O double bonds are assumed to be formed. The natural d-orbital occupancies on S and P, however, were calculated to be as low as 0.1 e, and therefore, an octet extension can hardly be expected. After the natural bond orbitals (NBO) search procedure was forced to attempt to form different Lewis structures of bonds and lone pairs, we defined the optimal Lewis structure, if a dominant structure exists at all, by the maximum electronic charge in Lewis orbitals. Indeed, sulfur obeys the octet rule in the optimal zwitterionic Lewis structures and does not form S=O double bonds. No dominant resonance structure could be found for H₃PO₄ where polarized PO ?-bond and zwitterionic PO bond structures exhibit similar weights.     

Modulation of Endothelin-A Receptor,Gα Subunit,and RGS2 Expression during H9c2 Cardiomyoblast Differentiation

In cardiac myocytes, growth responses depend on activation of G protein-coupled receptors interacting with G_q/11 protein subfamily members. Endothelin receptors of the ET_A subtype belong to this receptor group inducing hypertrophic responses. To understand the role of ET_A receptors and signal transduction proteins in modulating cell growth, we analyzed the pharmacological profile of this receptor, its level of expression together with those of Gα subunits and the RGS2 protein in cardiomyoblasts differentiating into the cardiac phenotype. H9c2 rat cardiomyoblasts were grown in the presence of 10% fetal bovine serum (FBS) or 1% FBS plus all-trans-retinoic acid to induce the cardiac phenotype. The pharmacological properties of ET_A receptors were investigated by competition-binding experiments, whereas the protein expression profile was analyzed by immunoblot and immunocytochemistry. The pharmacological profile of ET_A receptors changed during differentiation of cardiomyoblasts into cardiomyocytes, and the amount of expressed receptor appeared to increase. Immunocytochemistry also showed a marked increase of receptor expression on cell membranes of differentiated cardiomyocytes. Among the other signaling proteins examined, both Gα_q/11 and RGS2 expression decreased in cells with the cardiac phenotype. Our results demonstrate that the expression of key proteins (ET_A receptor, Gα_q/11, and RGS2) involved in signal transduction of hypertrophic stimuli is modulated during cell differentiation and correlates with the cardiac phenotype.     

[15N,1H]/[13C,1H]-TROSY for simultaneous detection of backbone 15N–1H, aromatic 13C–1H and side-chain 15N–1H2 correlations in large proteins

This paper describes a [¹⁵N,¹H]/[¹³C,¹H]-TROSY experiment for the simultaneous acquisition of the heteronuclear chemical shift correlations of backbone amide ¹⁵N–¹H groups, side chain ¹⁵N–¹H₂ groups and aromatic ¹³C–¹H groups in otherwise highly deuterated proteins. The ¹⁵N–¹H and ¹³C–¹H correlations are extracted from two subspectra of the same data set, thus preventing possible spectral overlap of aromatic and amide protons in the ¹H dimension. The side-chain ¹⁵N–¹H₂ groups, which are suppressed in conventional [¹⁵N,¹H)-TROSY, are observed with high sensitivity in the ¹⁵N–¹H subspectrum. [¹⁵N,¹H]/[¹³C,¹H]-TROSY was used as the heteronuclear correlation block in a 3D [¹H,¹H]-NOESY-[¹⁵N,¹H]/[¹³C,¹H]-TROSY experiment with the membrane protein OmpA reconstituted in detergent micelles of molecular weight 80000 Da, which enabled the detection of numerous NOEs between backbone amide protons and both aromatic protons and side chain ¹⁵N–¹H₂ groups.     

HPGMR不育花药能量代谢,H2O2的积累与雄性不育的关系

HPGMR农垦58s不育花药在单核早期、单核晚期、二核及三核期的COD、ATP酶活性普遍低于可育花药,少2～5条COD同工酶带,各发育时期的ATP含量也较低,并有H_2O_2的积累。     

H2S Donor,S-Propargyl-Cysteine,Increases CSE in SGC-7901 and Cancer-Induced Mice: Evidence for a Novel Anti-Cancer Effect of Endogenous H2S?

Background

S-propargyl-cysteine (SPRC), an H₂S donor, is a structural analogue of S-allycysteine (SAC). It was investigated for its potential anti-cancer effect on SGC-7901 gastric cancer cells and the possible mechanisms that may be involved.

Methods and Findings

SPRC treatment significantly decreased cell viability, suppressed the proliferation and migration of SPRC-7901 gastric cancer cells, was pro-apoptotic as well as caused cell cycle arrest at the G₁/S phase. In an in vivo study, intra-peritoneal injection of 50 mg/kg and 100 mg/kg of SPRC significantly reduced tumor weights and tumor volumes of gastric cancer implants in nude mice, with a tumor growth inhibition rate of 40–75%. SPRC also induced a pro-apoptotic effect in cancer tissues and elevated the expressions of p53 and Bax in tumors and cells. SPRC treatment also increased protein expression of cystathione-γ-lyase (CSE) in cells and tumors, and elevated H₂S levels in cell culture media, plasma and tumoral CSE activity of gastric cancer-induced nude mice by 2, 2.3 and 1.4 fold, respectively. Most of the anti-cancer functions of SPRC on cells and tumors were significantly suppressed by PAG, an inhibitor of CSE activity.

Conclusions

Taken together, the results of our study provide insights into a novel anti-cancer effect of H₂S as well as of SPRC on gastric cancer through inducing the activity of a new target, CSE.     

H2O2介导的H2S产生参与干旱诱导的拟南芥气孔关闭

以野生型拟南芥(Arabidopsis thaliana)及其突变体(atrbohD、atrbohF、atrbohD/F、atl-cdes、atd-cdes)和过表达株系(OEL-CDes、OED-CDes)为材料,利用药理学实验,结合分光光度法和激光共聚焦显微技术,探讨硫化氢(hydrogen sulfide,H2S)在干旱诱导的拟南芥气孔关闭中的作用及其与过氧化氢(hydrogen peroxide,H2O2)的关系.结果表明,H2S清除剂次牛磺酸(hypotaurine,HT)及合成抑制剂氨氧基乙酸(aminooxy acetic acid,AOA)、羟胺(hydroxylamine,NH2OH)和丙酮酸钾(potasium pyruvate,C3H3KO3)+氨水(ammonia,NH3)均可不同程度抑制干旱诱导的气孔关闭;干旱对OEL-CDes和OED-CDes植株气孔关闭的诱导作用明显,而atl-cdes和atd-cdes叶片气孔对干旱胁迫反应的敏感性下降;干旱胁迫能明显增加拟南芥保卫细胞中H2O2水平及叶片中H2S含量,提高D-/L-半胱氨酸脱巯基酶活性及基因表达量,而对突变体atrbohD、atrbohF和atrbohD/F没有显著影响.清除H2O2可减弱干旱胁迫对H2S含量和D-/L-半胱氨酸脱巯基酶活性的诱导效应.研究结果表明H2S位于H2O2下游参与干旱诱导拟南芥气孔关闭的信号转导过程.     

H2O2介导的H2S产生参与干旱诱导的拟南芥气孔关闭

以野生型拟南芥(Arabidopsis thaliana)及其突变体(atrbohD、atrbohF、atrbohD/F、atl-cdes、atd-cdes)和过表达株系(OEL-CDes、OED-CDes)为材料, 利用药理学实验, 结合分光光度法和激光共聚焦显微技术, 探讨硫化氢(hydrogen sulfide, H₂S)在干旱诱导的拟南芥气孔关闭中的作用及其与过氧化氢(hydrogen peroxide, H₂O₂)的关系。结果表明, H₂S清除剂次牛磺酸(hypotaurine, HT)及合成抑制剂氨氧基乙酸(aminooxy acetic acid, AOA)、羟胺(hydroxylamine, NH₂OH)和丙酮酸钾(potasium pyruvate, C₃H₃KO₃)+氨水(ammonia, NH₃)均可不同程度抑制干旱诱导的气孔关闭; 干旱对OEL-CDes和OED-CDes植株气孔关闭的诱导作用明显, 而atl-cdes和atd-cdes叶片气孔对干旱胁迫反应的敏感性下降; 干旱胁迫能明显增加拟南芥保卫细胞中H₂O₂水平及叶片中H₂S含量, 提高D-/L-半胱氨酸脱巯基酶活性及基因表达量, 而对突变体atrbohD、atrbohF和atrbohD/F没有显著影响。清除H₂O₂可减弱干旱胁迫对H₂S含量和D-/L-半胱氨酸脱巯基酶活性的诱导效应。研究 结果表明H₂S位于H₂O₂下游参与干旱诱导拟南芥气孔关闭的信号转导过程。     

Determination of Hα,Hβ and Hβ,C′ coupling constants in13C-labeled proteins

Summary A sensitive method to assign H protons stereospecifically as well as to determine rotamer populations about ₁, in two 3D experiments is presented. The SOFT-HCCH-COSY experiment allowed us to measure the³J(H,C) couplings, using constant time evolution of C in t₂ and C_aliphatic-selective decoupling during t₃. The SOFT-HCCH-E.COSY experiment allowed us to measure the³J(H,H) couplings, using constant time evolution of C in t₂, a small flip angle¹H excitation pulse in the second mixing time, and double-band-selective decoupling (aliphatic and carbonyl carbons) during t₃. The method was applied to ribonuclease T₁.     

Ca2+位于H2O2上游参与H2S诱导的拟南芥气孔关闭过程

以拟南芥为材料,利用药理学实验,结合分光光度法和激光共聚焦显微技术,研究了Ca2+在硫化氢(H2S)诱导拟南芥气孔关闭过程中的作用及其与过氧化氢(H2O2)的关系。结果表明： H2S诱导气孔关闭, Ca2+螯合剂EGTA和质膜Ca2+通道阻断剂硝苯地平(Nif)能不同程度抑制H2S诱导的气孔关闭,而内质网钙泵阻断剂毒胡萝卜素(Thaps)对H2S的作用无显著影响。由此推测, Ca2+参与调节H2S诱导的拟南芥气孔关闭过程,且胞质中Ca2+来源于胞外Ca2+的内流。另外, H2S诱导拟南芥叶片NADPH氧化酶基因AtRBOHD和AtRBOHF以及细胞壁过氧化物酶基因AtPRX34表达增强,促进叶片和保卫细胞中H2O2积累, EGTA对此起抑制作用,而外源CaCl2处理上调AtRBOHD、AtRBOHF和AtPRX34的表达。表明Ca2+可能位于H2O2上游参与H2S诱导的拟南芥气孔关闭过程。     

H2-A polymorphism contributes to H2-Eβ-mediated protection in collagen-induced arthritis

 Collagen-induced arthritis (CIA) is an animal model of auto-immune inflammatory polyarthritis which has features similar to rheumatoid arthritis (RA). Much like RA, susceptibility to mouse CIA is influenced by the major histocompatibility complex (MHC) and is restricted to the H2 haplotypes q and r. In previous experiments, we have found that the introduction of an H2-Eb ^d transgene in H2-A^q CIA-susceptible mice was able to protect these mice against disease development. More recently, we have proposed that the polymorphism of the first domain of the Eβ molecule modulates this protection, and that the presentation of a peptide from the third hypervariable region of the Eβ chain by the H2-A^q molecule plays an important role in this mechanism. In the present report, we investigated whether the H2-E-mediated protection is H2-A^q-specific and whether the source of collagen has any influence. While the source of collagen had no effect on the protection, our results showed that the H2-E molecule failed to protect B10.RIII (H2^r) mice against CIA. Further, the H2 haplotype r exerted a negative effect on the Eβ^d-mediated protection in H2-A^q-restricted disease. Our results provide additional proof that self-MHC-derived peptides, such as Eβ peptides, may play an important role in the T-cell repertoire education and/or modulation of the T-cell response in the periphery. Received: 29 May 1996 / Revised: 26 June 1996