Phenanthrene derivatives from Tamus communis

Six phenanthrene derivatives whose occurrence in T. communis is already reported and 5 and 6, previously described as the acetates after acetylation of the mixture of the two natural compounds, were isolated from the rhizomes of T. communis. ¹H and ¹³C NMR spectral data are reported.     

Alkaloids and olefinic acids from Cryptocarya amygdalina

From the bark of Cryptocarya amygdalina two new olefinic acids with a tetracyclo(4.3.0^2.4.0^3.7) non-8-enemoiety are reported. From the same source the benzylisoquinoline alkaloids orientaline and laudanidine are also reported.     

Kinetics of oxidation of ferrocene by tris-1,10-phenanthrolinecobalt(III) in t-butyl alcoholwater and acetonewater mixtures

Rate constants and activation parameters (ΔH^≠ and ΔS^≠)are reported for the oxidation of ferrocene by the tris-1,10-phenanthrolinecobalt(III) cation in t-butyl alcoholwater and in acetonewater solvent mixtures. Solvent effects on reactivity trends for these systems, for this same reaction in methanolwater mixtures, and for cobalt(II)-catalysed racemisation of Co(phen)_3³⁺ in t-butyl alcoholwater solvent mixtures are analysed into initial state and transition state contributions. The dependences of solubilities on solvent composition for ferrocene and for [Co(phen)₃](ClO₄)₃ in methanol, t-butyl alcohol, and acetonewater mixtures are also reported; these results are needed in order to establish solvent effects on the initial states of the reactions studied.     

High throughput chemical screening supports the involvement of Ca2+ in cyclic nucleotide-gated ion channel-mediated programmed cell death in Arabidopsis

Recently, we reported the role of Arabidopsis cyclic nucleotide-gated ion channel (AtCNGC) 11 and 12 in Ca²⁺-dependent physiological responses. AtCNGC11 and 12 have been reported to be involved in plant immunity, but whether these channels play additional physiological roles was not clear before. Using single and double knockout mutants, we have found that these channels play significant roles in Ca²⁺ signaling, which mediates several physiological processes, such as gravitropic bending and senescence. Here, we conducted a high throughput, non-biased chemical screen using the gain-of-function mutant of AtCNGC11 and 12, cpr22. Our data presented here indicates that Ca²⁺ but not K⁺ channel blockers suppress AtCNGC11/12-induced lethality. Our data further suggest that AtCNGC11 and 12 are involved in Ca²⁺-dependent, but not K⁺-dependent physiological responses in planta.     

Hymenolepis diminuta: membrane transport of glucose and beta-methylglucoside

Absorption kinetics of [¹⁴C]glucose and [β-methyl-¹⁴C]glucoside in Hymenolepis diminuta are reported. β-Methylglucoside (βMG) is a pure competitive inhibitor of [¹⁴C]glucose transport and has kinetic parameters, V_max and K_t, for transport similar to those reported for glucose. While absorbed ¹⁴C-βMG is not metabolized, transport of this glucose analog retains the general characteristics which have been established for glucose transport including: (1) Na⁺ dependence, (2) inhibition by K⁺, (3) sensitivity to phlorizin and various hexoses, (4) transport against an apparent concentration gradient, and (5) increase in worm water during accumulation. It is concluded that glucose and βMG are transported by the same system. The value of using βMG to study the mechanism of hexose transport and accumulation in H. diminuta is suggested.     

Multi-nuclear (119Sn, 13C, 1H), fourier-transform,N.M.R. studies of di- and tri-butylstannyl ethers of carbohydrates

¹¹⁹Sn-N.m.r. spectra are reported for toluene solutions of the tributylstannyl ethers of 2,3,4,6-tetra-O-methyl-d)-glucose, 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose, methyl 2,3-di-O-methyl-α-d-glucopyranoside, and methyl 4,6-O-benzylidene-α-d-glucopyranoside, and the dibutylstannyl ether of the last sugar. In the reaction of bis(tributyltin) oxide with methyl 4,6-O-benzylidene-α-d-glucopyranoside in toluene, HO-3 is much more reactive than HO-2. The presence of the various tin-containing species is readily apparent from the ¹¹⁹Sn-spectra. The importance of suppressing the nuclear Overhauser effect is demonstrated. The appearance of ¹¹⁹Sn satellites in the ¹³C-n.m.r. spectra demonstrates couplings of the types, ²J(¹¹⁹Sn-O-¹³C) and ³J(¹¹⁹Sn-O-C-¹³C), forthe first time, and, together with the ¹³C-chemical shifts, facilitates the determination of the site of substitution. The ¹¹⁹Sn-chemical shifts show that different states of coordination may be recognised. However, although different sites of substitution produce separate resonances, no simple relationship between shift and position is found. ¹³C-Chemical shifts are reported for methyl 4,6-O-benzylidene-α-d-glucopyranoside and its tributylstannyl ethers, and substituent effects are discussed.     

Synthesis, structure and Mössbauer characterization of polymeric iron(II) complexes with bidentate thiourea ligands

Complexes of FeCl₂ with the known bis(3-methyl-2-thione-imidazolyl)methane (L¹) and the new bis(3-tert-butyl-2-thione-imidazolyl)methane (L²) are reported. For both [L¹FeCl₂]_n (3) and [L²FeCl₂]_n (4) X-ray crystallography reveals that 1D-polymeric chain structures are present in the solid state, with the two mercaptoimidazolyl units of L¹ and L² coordinating to different metal ions. Complexes 3 and 4 are further characterized by Mössbauer spectroscopy and SQUID magnetometry. NMR spectroscopy suggests that the complexes largely dissociate in polar solvents. X-ray structures of L² and its precursor bis(imidazolium) salt are also reported.     

X-ray crystallographic and high-resolution NMR spectroscopy characterization of 4,6-di-O-acetyl-2,3-dideoxy-alpha-D-erythro-hex-2-enopyranosyl sulfamide

Single crystal X-ray diffraction and high-resolution ¹H and ¹³C NMR spectral data for 4,6-di-O-acetyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranosyl sulfamide, a selective inhibitor of carbonic anhydrase isozyme IX, are reported. The ⁰H₅ was found to be the preferred form for this glycosyl sulfamide, both in the crystal lattice and in solution.     

13C NMR spectral and conformational analysis of 8-O-4′ neolignans

The ¹³C NMR spectra of the erythro and threo forms of representative members of the 8-O-4′ type of neolignans were recorded and the signals assigned. Based on these assignments and on the comparison with previously reported ¹H NMR data, the most probable conformations for the above mentioned stereoisomers are suggested.     

Cloning, expression and characterization of phenylalanine ammonia-lyase from Rhodotorula glutinis

The industrial-scale production of phenylalanine ammonia-lyase (PAL) mainly uses strains of Rhodotorula. However, the PAL gene from Rhodotorula has not been cloned. Here, the full-length gene of PAL from Rhodotorula glutinis was isolated. It was 2,121 bp, encoding a polypeptide with 706 amino acids and a calculated MW of 75.5 kDa. Though R. glutinis is an anamorph of Rhodosporium toruloides, the amino acid sequences of PALs them are not the same (about 74 % identity). PAL was expressed in E. coli and characterized. Its specific activity was 4.2 U mg^?1 and the k _cat/K _m was 1.9 × 10⁴ mM^?1 s^?1, exhibiting the highest catalytic ability among the reported PALs. The genetic and biochemical information reported here should facilitate future application in industry.     

Identification of cardiac glycosides in fractions from Periploca forrestii by high-performance liquid chromatography/diode-array detection/electrospray ionization multi-stage tandem mass spectrometry and liquid chromatography/nuclear magnetic resonance

Cardiac glycosides are a class of naturally occurring compounds that are characterized by some interesting biological activities and are widely distributed in the plant kingdom and can also be found in some animals. There is an interest in the chemical characterization of these molecules due to their toxicity and their use in medicines. In the study reported here, a combination of electrospray ionization tandem mass spectrometry with high-performance liquid chromatography equipped with diode-array detector (HPLC-DAD/ESI-MSⁿ), and hyphenation to both liquid chromatography and nuclear magnetic resonance spectroscopy (HPLC/NMR) were utilized for the on-line analyses of cardiac glycosides from Periploca forrestii. The fragmentation patterns and ¹H NMR spectra of nine isolated cardiac glycosides were investigated; their fragmentation rules and ¹H NMR spectral characteristics were summarized and applied to the structural identification of similar constituents in fractions from P. forrestii. As a result, a total of nine trace cardiac glycosides were tentatively determined by analyses of accurate molecular masses, representative fragment ions and characteristic ¹H NMR signals provided by HPLC/high-resolution mass spectrometry (HRMS), HPLC-DAD/ESI-MSⁿ and HPLC/¹H NMR experiments, respectively. Of these, eight (2–9) are new compounds and one (1) is reported from P. forrestii for the first time. Results of the present study can benefit the rapid identification and targeted isolation of new cardiac glycosides from crude plant extracts.     

Fully automated synthesis and initial PET evaluation of [11C]PBR28

Fully automated synthesis and initial PET evaluation of a TSPO radioligand, [¹¹C]PBR28 (N-(2-[¹¹C]methoxybenzyl)-N-(4-phenoxypyridin-3-yl)acetamide), are reported. These results facilitate the potential preclinical and clinical PET studies of [¹¹C]PBR28 in animals and humans.     

Development of Mice with Brain-Specific Deletion of Floxed Glud1 (Glutamate Dehydrogenase 1) Using Cre Recombinase Driven by the Nestin Promoter

In the brain, Glud1-encoded glutamate dehydrogenase plays a major role in the recycling of the neurotransmitter glutamate. We recently reported a new model of brain-specific Glud1 null mice (Cns-Glud1 ^?/?) lacking glutamate dehydrogenase in the central nervous system. Cns-Glud1 ^?/? mice exhibit reduced astrocytic glutamate breakdown and redirection of glutamate pathways without altering synaptic transmission. Cns-Glud1 ^?/? mice were generated using LoxP and Nestin-Cre technology. Nestin-Cre mice are widely used to investigate gene deletion in the central nervous system. However, the Nes-Cre transgene itself was reported to induce a phenotype related to body weight gain. Here, we review the potential side-effects of Nes-Cre and analysed Cns-Glud1 ^?/? body weight gain. Overall, Nestin-Cre mice may exhibit transient and moderate growth retardation during the few weeks immediately following weaning. Pending appropriate controls and homogenization of the genetic background, Nestin-Cre technology is a valuable tool enabling disruption of genes of interest in the central nervous system.     

13C-N.M.R.-spectroscopic investigation of agarose oligomers

A complete, unambiguous assignment of all of the ¹³C-n.m.r.-spectral signals of agarose oligomers produced by enzymic hydrolysis has been achieved. The ¹J¹³C-H coupling constants are reported, and the chemical shifts and coupling constants of both the agarose polymer and oligomers are compared.     

Inverse PCR-Based Method for Isolating Novel SINEs from Genome

Short interspersed elements (SINEs) are moderately repetitive DNA sequences in eukaryotic genomes. Although eukaryotic genomes contain numerous SINEs copy, it is very difficult and laborious to isolate and identify them by the reported methods. In this study, the inverse PCR was successfully applied to isolate SINEs from Opsariichthys bidens genome in Eastern Asian Cyprinid. A group of SINEs derived from tRNA^Ala molecular had been identified, which were named Opsar according to Opsariichthys. SINEs characteristics were exhibited in Opsar, which contained a tRNA^Ala-derived region at the 5′ end, a tRNA-unrelated region, and AT-rich region at the 3′ end. The tRNA-derived region of Opsar shared 76 % sequence similarity with tRNA^Ala gene. This result indicated that Opsar could derive from the inactive or pseudogene of tRNA^Ala. The reliability of method was tested by obtaining C-SINE, Ct-SINE, and M-SINEs from Ctenopharyngodon idellus, Megalobrama amblycephala, and Cyprinus carpio genomes. This method is simpler than the previously reported, which successfully omitted many steps, such as preparation of probes, construction of genomic libraries, and hybridization.     

Primary production and biomass on a Dutch salt marsh: emphasis on the below-ground component

The primary production and below-ground biomass of angiosperms were measured in four almost monospecific vegetation stands situated on a salt marsh along the Oosterschelde estuary, The Netherlands. Maximum below-ground biomass values found for Spartina anglica, Elymus pycnanthus, Halimione portulacoides and Triglochin maritima, were very high relative to values reported from other European salt marshes: 12 586, 9 717, 17 737 and 16 121 g m^-2 respectively. These relatively high values may be due to the fineness of the sieve used, compared to other studies. The actual values are likely to be even higher because the sample treatment has probably caused loss of fine root material. Below-ground production estimates, based on the difference between maximum and minimum biomass, yielded: 6 044 g m^-2 yr^-1 for Spartina, 4 421 g m^-2 yr^-1 for Elymus, 7 799 g m^-2 yr^-1 for Halimione and 3 475 g m^-2 yr^-1 for Triglochin. This high production is mainly concentrated in the deeper layers of the root environment (20–60 cm). Although these production figures are considerably higher than those generally reported for comparable species or vegetation types in Europe, statistical evidence suggests that, for the first three species, they are real values rather than figures caused by random fluctuations.     

Grimontia indica AK16T,sp. nov., Isolated from a Seawater Sample Reports the Presence of Pathogenic Genes Similar to Vibrio Genus

Grimontia indica strain AK16^T sp. nov. is the type strain of G. indica sp. nov. a new species within the genus Grimontia. This strain, whose genome is described here, was isolated from seawater sample collected from southeast coast of Palk Bay, India. G. indica AK16^T is a Gram-negative, facultative aerobic rod shaped bacterium. There are only two other strains in the genus Grimontia one of which, Grimontia hollisae CIP 101886^T, is a reported human pathogen isolated from human stool sample while the other, ‘Grimontia marina IMCC5001^T’, was isolated from a seawater sample. As compared to the pathogenic strain Grimontia hollisae CIP 101886^T, the strain AK16^T lacks some genes for pathogenesis like the accessory colonization factors AcfA and AcfD, which are required for the colonization of the bacterium in the host body. While it carries some pathogenesis genes like OmpU, which are related to pathogenesis of Vibrio strains. This suggests that the life cycle of AK16^T may include some pathogenic interactions with marine animal(s), or it may be an opportunistic pathogen. Study of the Grimontia genus is important because of the severe pathogenic traits exhibited by a member of the genus with only three species reported in total. The study will provide some vital information which may be useful in future clinical studies on the genus.     

Nickel(II) ion-catalyzed hydrolysis of acetyl esters of 2-pyridineoxime derivatives: Effects of geometry around central metal atom on the efficiency of metal ion catalysis

The kinetics of the Ni(II)-catalyzed ester hydrolysis of O-acetyl-2-pyridine-carboxaldoxime, O-acetyl-2-acetylpyridineketoxime, and O-acetyl-6-carboxy-2-pyridine-carboxaldoxime are measured and the values of various k_cat parameters are calculated for reaction paths involving one metal ion (k_cat^W and k_cat^OH) and two metal ions k_cat^A and k_cat^B). Examination of the kinetic data reveals that the k_cat^W and k_cat^OH paths for the Ni(II)-catalyzed reactions involve the same mechanism as those for the previously reported Cu(II)-catalyzed reactions. For the k_cat^A and k_cat^B paths, the mechanism involving binuclear Ni(II) ions is preferred by analogy with the previously reported Zn(II)-catalyzed reactions. Comparison of k_cat^OH values for the Cu(II)- and Ni(II)-catalyzed hydrolysis of 1–3 indicates that markedly different steric effects are exerted by the substituents of 2 and 3 on the catalytic behavior of the two metal ions. This is explained in terms of differences in the fit of the metal ions in the metal complexes of 1–3. Present results demonstrate that slight changes in the geometry around the central metal atom can affect the catalytic outcome significantly. The implications of the present results on metal substitution in metalloenzymes are also discussed.     

Nucleotide binding affinities of the intact proton-translocating transhydrogenase from Escherichia coli

Transhydrogenase (E.C. 1.6.1.1) couples the redox reaction between NAD(H) and NADP(H) to the transport of protons across a membrane. The enzyme is composed of three components. The dI and dIII components, which house the binding site for NAD(H) and NADP(H), respectively, are peripheral to the membrane, and dII spans the membrane. We have estimated dissociation constants (K_d values) for NADPH (0.87 μM), NADP⁺ (16 μM), NADH (50 μM), and NAD⁺ (100-500 μM) for intact, detergent-dispersed transhydrogenase from Escherichia coli using micro-calorimetry. This is the first complete set of dissociation constants of the physiological nucleotides for any intact transhydrogenase. The K_d values for NAD⁺ and NADH are similar to those previously reported with isolated dI, but the K_d values for NADP⁺ and NADPH are much larger than those previously reported with isolated dIII. There is negative co-operativity between the binding sites of the intact, detergent-dispersed transhydrogenase when both nucleotides are reduced or both are oxidised.     

Synthesis,radiochemistry and biological evaluation of technetium-99m complexes with 1,8-diamine-3,6-dithiaoctane (DDO) ligands

The synthesis, radiochemical analysis and biological characteristics of some 1,8-diamine-3,6-dithiaoctane derivatives labelled with Tc-99m are reported. Analysis by HPLC shows that most of the ^99mTc-chelates are multicomponent. Furthermore, almost all ^99mTc-complexes isolated by HPLC are lipophilic and stable in vitro. The biodistributions of the most lipophilic of these complexes were evaluated in mice. The N-morpholinylethyl and N,N'′-bisalicylyl derivatives of 1,8-diamine-3,6-dithiaoctane yielded ^99mTc-complexes which exhibit considerable uptake and retention in organs of interest, such as the heart and the brain.