Preparation and characterization of oxovanadium(IV), acetatomanganese(III), chloroiron(III), nickel(II), copper(II), zinc(II) and palladium(II) complexes of 3,3′-(1,2-phenylenediimino)diacrolein

The oxovanadium(IV), acetatomanganese(III), chloroiron(III), nickel(II), copper(II), zinc(II) and palladium(II) of 3,3′-(1,2-phenylenediimino)diacrolein were prepared and investigated by means of mass, electronic, vibrational, NMR and ESR spectroscopy as well as magnetic susceptibility measurements. The acetatomanganese(III) and chloroiron(III) complexes were confirmed to be of high spin type. The absorption bands appearing in the energy range greater than 23 000 cm⁻¹ were attributed to π→π^* transitions within a ligand molecule and charge- transfer transitions from metal to ligand. The metal complexes assume the square-planar configuration type since the ligand-field bands were detected in the 12 700–18 500 cm⁻¹ region. Strong bands appearing at 1601 and 1627 cm⁻¹ were assigned to the CC and CO stretching vibrational modes, respectively, and were shifted to lower frequency upon metal-coordination. A VO stretching band was observed at 982 cm⁻¹ for the oxovanadium(IV) complex and a CO stretching band was observed at 1547 cm⁻¹ for the acetatomanganese(III) complex. Upon complex formation the amine proton signal is found to vanish and the aldehydic methine proton signal in the lowest field is shifted upfield for the nickel(II), zinc(II) and palladium(II) complexes. ¹³C NMR spectra support the coordination structure of the complexes which is revealed by ¹H NMR spectra. As judged by the spin Hamiltonian parameters, the oxovanadium(IV) complex is of a square- planar type with an unpaired electron in the d_xy orbital and the copper(II) complex assumes a distorted square-planar coordination due to the presence of five- and six-membered chelate rings with an unpaired electron in the d_x2−y2 orbital.     

Detection and quantification of α-keto-δ-(N(G),N(G)-dimethylguanidino)valeric acid: a metabolite of asymmetric dimethylarginine

Nitric oxide is an ubiquitary cell signaling substance. Its enzymatic production rate by nitric oxide synthase is regulated by the concentrations of the substrate L-arginine and the competitive inhibitor asymmetric dimethylarginine (ADMA). A newly recognized elimination pathway for ADMA is the transamination to α-keto-δ-(N(G),N(G)-dimethylguanidino)valeric acid (DMGV) by the enzyme alanine-glyoxylate aminotransferase 2 (AGXT2). This pathway has been proven to be relevant for nitric oxide regulation, but up to now no method exists for the determination of DMGV in biological fluids. We have developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of DMGV. D(6)-DMGV was used as internal standard. Samples were purified online by column switching, and separation was achieved on a porous graphitic carbon column. The calibration was linear over ranges of 10 to 200 nmol/L for plasma and 0.1 to 20 μmol/L for urine. The intra- and interday accuracies and precisions in plasma and urine were better than 10%. In plasma samples, DMGV was present in concentrations between 19.1 and 77.5 nmol/L. In urine samples, concentrations between 0.0114 and 1.03 μmol/mmol creatinine were found. This method can be used as a tool for the scientific investigation of the ADMA conversion to DMGV via the enzyme AGXT2.     

IR and Raman study on the interactions of the 5′-GMP and 5′-CMP phosphate groups with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III)

The chief motive behind this research is the interest provoked by the presence of metal ions as necessary stabilizers of the negative charges of phosphate groups in nucleic acids. The effect that the presence of different metal ions produces on the band principally assigned to the nu(s) PO(3)(2-) mode has been studied using FT-IR and FT-Raman spectroscopy. The results obtained reveal the diagnostic capacity of these techniques in determining the type of metal ion interaction with respect to the mononucleotides that form DNA and RNA, providing a tool for improving the knowledge of the stabilizing or destabilizing effects of these ions on such macromolecules. The metal complexes of the ribonucleotides 5'-CMP and 5'-GMP with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III) were obtained in this study. After studying and analyzing the IR and Raman spectra of all these complexes and comparing them with the spectra of the corresponding disodium salts, it was verified that, independently of the type of nucleotide involved, the presence of the metal in the vicinity of the phosphate group produces an alteration in the aforementioned nu(s) PO(3)(2-) band. This effect is related to the type of interaction that the phosphate group has with the metal. Three components are observed: (1) one near 983-975 cm(-1) (detectable in IR and Raman), associated with phosphate groups in an electrostatic type of interaction with the metal ion, separated by two or more water molecules; (2) another near 989-985 cm(-1) (only in IR), associated with phosphate groups in indirect interaction through the water molecules of the coordination sphere of the metal ions; and (3) the IR and Raman bands near 1014-1001 cm(-1), which represent phosphate groups directly bonded to the metal ion. These results are supported by the behavior of 5'-CMP in aqueous solution in the presence of Mg(II) ions.     

Yields and accumulations of N and P in farmer-managed intercrops of maize–pigeonpea in semi-arid Africa

Maize (Zea mays L.) is a major staple food in Sub-Saharan Africa but low soil fertility, limited resources and droughts keep yields low. Cultivation of maize intercropped with pigeonpea (Cajanus cajan L. Millsp.) is common in some areas of eastern and southern Africa. The objectives of this study were (1) to investigate dry matter, nitrogen (N) and phosphorus (P) accumulation in different plant components of maize–pigeonpea intercropping systems and (2) to report the effects of the intercrops on soil fertility. Maize–pigeonpea intercrops were compared to sole maize grown using farmersȁ9 practices. Intercropping maize and pigeonpea increased (P < 0.05) total system yield compared to sole maize in terms of biomass, N and P accumulation. Pigeonpea planted in maize did not reduce (P < 0.05) the accumulation of dry matter, N nor P in the maize grain. The harvest indices of maize, calculated on basis dry matter, N or P did not differ either (P < 0.05). Total soil C and N contents and inorganic N content, nitrate and ammonium, were not affected by two seasons of maize–pigeonpea intercropping compared to sole maize (P > 0.11). Nitrate and ammonium levels in soil were still not affected by the treatments after the soils were incubated in anaerobic conditions for 8 days at 37°C (P > 0.11). However, pigeonpea added up to 60 kg of N ha⁻¹ to the system and accumulated up to 6 kg of P ha⁻¹ and only 25% of this N and P were exported in the grain. In conclusion, beside the added grain yield of pigeonpea in the intercropped systems, pigeonpea increased the recirculation of dry matter, N and P, which may have a long-term effect on soil fertility. Furthermore, the stems from pigeonpea contributed to household fuel wood consumption. The intercropped system thus had multiple benefits that gave significant increase in combined yield per unit area without additional labour requirements. The main requirement in order to up-scale the maize–pigeonpea intercropping approach is sufficient supply of high-quality pigeonpea seeds.     

Synthesis, Characterization and Antitumor Studies of Mn(II), Ni(II), Cu(II) and Zn(II) Complexes of N-Nicotinoyl-N′-o-Hydroxythiobenzhydrazide

A new ligand N-Nicotinoyl-N-o-hydroxythiobenzhydrazide (H₂Notbh) forms complexes [Mn(Notbh)(H₂O)], [M(Notbh)] [M=Ni(II) Cu(II) and Zn(II)] which were characterized by various physico-chemical techniques. All the metal complexes were observed to inhibit the growth of tumor in vitro, whereas, ligand did not. In vivo administration of these complexes resulted in prolongation of survival of tumor bearing mice. Tumor bearing mice administered with metal complexes showed reversal of tumor growth associated induction of apoptosis in lymphocytes. The paper discusses the possible mechanisms and therapeutic implication of the H₂Notbh and its metal complexes in tumor regression and tumor growth associated immunosuppression.     

Speciation history of three closely related pines Pinus mugo (T.), P. uliginosa (N.) and P. sylvestris (L.)

Nucleotide polymorphisms at genomic regions including 17 nuclear loci, two chloroplast and one mitochondrial DNA fragments were used to study the speciation history of three pine species: dwarf mountain pine (Pinus mugo), peat‐bog pine (P. uliginosa) and Scots pine (P. sylvestris). We set out to investigate three specific speciation scenarios: (I) P. uliginosa is a homoploid hybrid between the other two, (II) the species have evolved without gene flow after divergence and (III) there has been substantial gene flow between the species since their divergence. Overall, the genetic data suggest that P. mugo and P. uliginosa share the same gene pool (average net divergence of 0.0001) and that the phenotypic differences (e.g. growth form) are most likely due to very limited areas of the genome. P. mugo and P. uliginosa are more diverged from P. sylvestris than from each other (average net divergence of 0.0027 and 0.0026, respectively). The nucleotide patterns can best be explained by the divergence with migration speciation scenario, although the hybrid speciation scenario with small genomic contribution from P. sylvestris cannot be completely ruled out. We suggest that the large amount of shared polymorphisms between the pine taxa and the lack of monophyly at all loci studied between P. sylvestris and P. mugo–P. uliginosa can largely be explained by relatively recent speciation history and large effective population sizes but also by interspecific gene flow. These closely related pine taxa form an excellent system for searching for loci involved in adaptive variation as they are differentiated in phenotype and ecology but have very similar genetic background.     

Somatic antigens of Pseudomonas aeruginosa. The structure of O-specific polysaccharide chains of the lipopolysaccharides from P. aeruginosa O1 (Lányi), O3 (Habs), O13 and O14 (Wokatsch), and the serologically related strain NCTC 8505

Lipopolysaccharides from Pseudomonas aeruginosa O1 (Lányi classification), O3 (Habs classification), O13 and O14 (Wokatsch classification), and strain NCTC 8505, which is also related to serogroup O3 (Habs), have structurally similar O-specific polysaccharide chains built up of tetrasaccharide repeating units involving L-rhamnose (Rha), 2-acetamido-2-deoxy-D-glucose (GlcNAc), 2-acetamido-2-deoxy-L-galacturonic acid (GalNAcA), and a di-N-acyl derivative of bacillosamine (BacN): 2,4-diacetamido-2,4,6-trideoxy-D-glucose or 2-acetamido-2,4,6-trideoxy-4-[(S)-3-hydroxybutyramido]-D-glucose. The latter derivative was obtained free by solvolysis with hydrogen fluoride of carboxyl-reduced Habs O3 polysaccharide, and was identified by 1H-nuclear magnetic resonance spectroscopy and by mass spectrometry of the corresponding methylated alditol. Habs O3, Lányi O1, and Wokatsch O14 polysaccharides contained O-acetyl groups. Solvolysis with hydrogen fluoride of the native Habs O3 polysaccharide resulted in selective cleavage of the glycosidic linkages of 6-deoxy sugars to give the trisaccharide fragment involving all three N-acylated amino sugars. Similar solvolysis of NCTC 8505 polysaccharide afforded a mixture of disaccharide and trisaccharide with N,N'-diacetylbacillosamine at the reducing end. Smith degradation of Habs O3 polysaccharide resulted in selective oxidation of rhamnose to give a glycoside of a trisaccharide with glyceraldehyde as the aglycone. Smith degradation of NCTC 8505 polysaccharide was complicated by the formation of the glycoside of a trisaccharide with an aglycone of unknown structure. A trisaccharide with rhamnose at the reducing end was also isolated after Smith degradation of the latter polysaccharide. Analysis of the composition and structure of all oligosaccharides obtained, and detailed examination of the 13C-nuclear magnetic resonance spectra of these oligosaccharides, and of both intact and modified polysaccharides, revealed the following structures of the repeating units. The structure for the NCTC 8505 polysaccharide differs from that proposed previously [Tahara, Y. and Wilkinson, S.G. (1983) Eur. J. Biochem. 134, 299-304] in the configurations assigned to the glycosidic linkages of rhamnose and bacillosamine. The results obtained show the P. aeruginosa strains studied to represent three different O-serotypes in a single O-serogroup (Formula: see text).     

Incidental finding of double minutes (DM), single minutes (SM), homogenously staining regions (HSR), premature chromosome condensation (PCC), and premature centromere division (PCD)?

The incidental finding of DM's, minutes, HSR's, PCC, and PCD in two completely unrelated cases--one is a prenatal diagnosis in a twin pregnancy complicated by hydramnios and feto-fetal exsanguination, the other is an adult Klinefelter patient--raises the question whether such findings are coincidental or whether there is a common denominator in such cases. Possible relationships between these phenomena and the observed cases are discussed.     

Interaction of Adenosine 5′-Triphosphate with Metal Ions X-ray Structure of Ternary Complexes Containing Mg(II), Ca(II), Mn(II), Co(II), ATP and 2,2′ -Dipyridylamine

Abstract

The X-ray structures of the isomorphous Mg²⁺, Ca²⁺, Mn²⁺ and Co²⁺ complexes of ATP have been determined. The metal ions are wrapped in hexa-coordination by the α, β and γ phosphate groups of two ATP molecules thus blocking the interaction of the metal ions with the adenine base. A second metal ion which is fully hydrated, M(H₂O)²⁺ ₆, is engaged in a strong hydrogen bond with the γ phosphate group of ATP and suggests a possible step in facilitating the cleavage between the β and γ phosphates in phosphoryl transfer reactions.     

Synthesis, characterization and antitumor studies of N-aroyl-N′-thioaroylhydrazines and their Co(II), Ni(II), Cu(II) and Zn(II) complexes

N-Salicyloyl-N-p-hydroxythiobenzohydrazide (H₂STPH) and N-benzoyl-N-thiobenzohydrazide (H₂BTBH) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes were prepared and characterized by physicochemical studies. IR and NMR spectral studies imply dibasic tetradentate behaviour of the ligands bonding through `thiolato' sulfur, enolic oxygen and the two hydrazinic nitrogens in a polymeric fashion. The electronic spectra indicate [Ni(STPH)(H₂O)₂], [Co(STPH)(H₂O)₂] to be distorted octahedral while [Cu(BTBH)] has a square-planar geometry. In vitro antitumor results of the ligand and the complexes on P-815 (murine mastocytoma) and L-929 (murine fibroblast) indicate that these compounds show significant inhibition of ³H-thymidine and ³H-uridine incorporation in DNA and RNA, respectively, in these tumor cells at dose levels of 1, 2.5 and 5 g cm^–3. Antitumor studies suggest that [Cu(BTBH)] has significant dose dependent inhibitory effect on DNA synthesis. In vivo administration of [Cu(BTBH)] and [Ni(STPH)(H₂O)₂] resulted into prolongation of life span of Dalton's Lymphoma (DL) bearing mice.     

Synthesis and spectroscopic studies of platinum(II) complexes of N,N′-dicyclohexylethylenediamine

The platinum(II) complexes of the formula [Pt(DCHEDA)X₂], where DCHEDA is N,N′-dicyclohexylethylenediamine and X⁻ is CL⁻, Br⁻, I⁻, 0.5C₂O₄²⁻ (oxalate), 0.5C₃H₂O₄²⁻ (malonate), 0.5C₉H₄O₆²⁻ (4-carboxyphthalate), 0.5S₂O₃²⁻ or 0.5SO₄²⁻, have been synthesized and characterized by UVVis, IR, and ¹H NMR spectral techniques. All the above complexes are non-electrolytes in DMF/H₂O, except the sulphate complex which becomes a 1:1 electrolyte after incubation for 24 h at 28 °C. The halide complexes were also studied by X-ray photoelectron spectroscopy and these data suggest that there is π-bonding from platinum to halide in these complexes. The oxalate, malonate and sulphate bind in their complexes as bidentate ligands to platinum through two oxygen atoms whereas the thiosulphate in its complex binds as a bidentate ligand to platinum through one oxygen atom and one sulphur atom.     

Subunit structure and higher order assembly of the hemocyanins of the Melongenidae family: Melongena corona (Gmelin), Busycon canaliculatum (Linné), B. carica (Gmelin), B. contrarium (Conrad), and B. spiratum (Lamarck)

1. The hemocyanins of the Melongenidae family of marine gastropods: Melongena corona, Busycon canaliculatum, B. carica, B. contrarium, and B. spiratum exist in solution as multi-decameric aggregates characterized by sedimentation coefficients of approximately 105 S, 130 S, 150 S, 170 S, and higher values, corresponding to di-, tri-, tetra-, penta-, and larger multi-decameric particles. 2. The hemocyanins of B. contrarium and B. carica seem to form the largest decameric aggregates with the tri- to penta-decamers respresenting the major constitutents. Scanning transmission electron microscopy (STEM), both of unstained, freeze-dried and negatively-stained specimens, shows the presence of discrete aggregates consisting of up to ten decameric units. 3. The particle masses as determined by STEM mass measurements for individual molecules gave integral multiples of from 4.2 x 10(6) to 4.4 x 10(6) daltons ranging from about 8.2 x 10(6) daltons for the typical di-decamer of B. canaliculatum hemocyanin to as high as about 39 x 10(6) and 43 x 10(6) for the nano-and deca-decamers of B. contrarium hemocyanin. 4. The appearance of the higher multi-decamers in both negatively-stained and freeze-dried specimens suggest that they are formed by the addition of decameric units to a single di-decameric unit "tail-wise" in both directions. The higher aggregates formed seem to terminate with a closed head or collar at both ends of the assembly.     

Complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 3′AMP and 2′AMP

Derivatives of Co(II), Ni(II), Cu(II) and Zn(II) with 3′AMP and 2′AMP were synthesized and characterized by IR UV-Vis and fluorescence spectroscopy. There seems to be bonding of the metal ion to the base in all cases. The activation test, using the complexes as allosteric labels, was carried out with rabbit muscle glycogen phosphorylase b, but the enzyme was not activated, confirming that the phosphate group must necessarily be bonded to position 5′ of the ribose in order to activate this enzyme.     

Frances Lawrence Parker (1906–2002), micropaleontologist and pioneer of paleoceanography

Frances L. Parker made important contributions to the knowledge of benthic and planktonic Foraminifera, both in respect to taxonomy and to biogeographic and stratigraphic distributions. Her work became part of the foundations of modern paleoceanography, which may be said to begin with the results of the Swedish Deep-Sea Expedition (R/V Alabatross, 1947–1948). Among her most significant works is a demonstration of warm-cold cycles in the Mediterranean, based on Albatross cores, a reorganization of the classification of recent planktonic foraminifers, and a study of lineages in planktonic foraminifers for the Late Cenozoic.     

Strains of JC virus in Amerind-speakers of North America (Salish) and South America (Guaraní), Na-Dene-speakers of New Mexico (Navajo), and modern Japanese suggest links through an ancestral Asian population

Previously we showed that strains of human polyoma virus JC among the Navajo in New Mexico, speakers of an Athapaskan language in the Na-Dene language phylum, and among the Salish people in Montana, speakers of a language of the Salishan group in the Amerind family, were mainly of a northeast Asian genotype found in Japan (type 2A). We now report partial VP1-gene, regulatory region, and complete genome sequences of JC virus (JCV) from the Guaraní Indians of Argentina. The Tupí-Guaraní language represents the Equatorial branch of the Amerind language family proposed by Greenberg ([1987] Language in the Americas, Stanford: Stanford University Press). The partial VP1 gene sequences of the Guaraní revealed several variants of strains found in northeast Asia (Japan), as did the Salish. In contrast, the strains in the Navajo largely conformed to the prototype type 2A sequence (MY). Phylogenetic reconstruction with both the neighbor-joining and maximum parsimony methods utilized three complete Guaraní JCV genome sequences, three genomes from the Salish people, and 27 other complete JCV genomes, including three from the Navajo and three from Japan. Both trees showed that all type 2A JCV strains from the North and South Americans are closely related phylogenetically to strains in present-day Japan. However, variant sites in the coding regions, the T-antigen intron, and the regulatory region link the type 2A strains in Amerind groups (Guaraní and Salish), but differentiate them from those in a Na-Dene-speaking (Navajo) population. The data suggest separation from a population ancestral to modern Japanese, followed by a second division within the ancestral group that led to Amerind- and Na-Dene-speaking groups. The data cannot, however, localize the latter split to the Asian mainland (two migrations) or to North America (one migration).     

Differential Responses of N：P Stoichiometry of Leymus chinensis and Carex korshinskyi to N Additions in a Steppe Ecosystem in Nei Mongol

The typical steppe ecosystems in China are now being increasingly degraded due mainly toovergrazing. To determine the limiting nutrients is of significance in order to find out ways of successfullyrestoring the degraded steppe. In addition to field fertilization experiments, N:P stoichiometry is an alternative,but argumentative tool to study nutrient limitation. In this study, we used these two approaches to identifythe most limiting nutrient element at the species level. Furthermore, nutrient addition experimentprovides an effective means to test our hypothesis that N:P stoichiometry will remain constant becauserelatively narrow range of N:P ratio in tissues of the terrestrial plants is an important adaptive mechanismfor plants to survive on earth. For these purposes, we designed a field experiment to examine theresponses of biomass and N:P stoichiometry of the two dominant species -- Leyrnus chinensis (Trin.)Tzvel. and Carex korshinskyiKom. -- to N fertilization at rates of O, 5, 15, 30, 50 and 80 g NH4NO3.m-2.a-~in two adjacent sites, one being excluded animal grazing for 22 years (site A), and another being free ofgrazing for only two years (site B) before the experiment was carried out. No effects of N fertilization weredetected in the first year as reflected by the aboveground biomass and P concentrations of the twospecies. The regression analysis showed that N:P ratios of two species of both sites remained constant inthe second year. N fertilization significantly increased the N concentrations of two species in both years,while only significantly increased the P contents of the two species in the second year. N and P contentsof the two species were significantly correlated in all cases in 2001. Our results suggest that theL. chinensis was in short of N in site B while the growth of C. korshinskyi was limited by P in site A, andthere is a significant synergistic relationship between tissue N and P concentrations in 2001. Our hypothesiswas valid on the species level since N:P ratio of the two species remained constant with increasing Napplication rates after two years of fertilization. We argue that it may be inappropriate to define an ecosystemwhich is limited by certain nutrient elements since the responses of coexisting species present in acommunity to nutrient additions can vary tremendously.