Genotype-independent leaf disc transformation of potato (Solanum tuberosum) using Agrobacterium tumefaciens

Summary Leaves of the in vitro grown potato cultivars Bintje, Berolina, Desiree, and Russet Burbank were wounded and co-cultivated with Agrobacterium strains having chimeric bar and nptII genes on a disarmed T-DNA. Each leaf from these cultivars formed numerous calli on kanamycin-containing medium, and almost all calli regenerated shoots. For Russet Burbank, it was necessary to include AgNO₃ in the medium to obtain efficient shoot regeneration. The transformed plants have one to a few copies of the T-DNA, show NPT-II and PAT activities, and are resistant to high doses of the commercial preparation of phospinotricin (glufosinate). Almost no somaclonal variation was detected in trans-genic plants.     

Interaction of thymic peptide thymosinα 1 with vasoactive intestinal peptide (VIP) receptors

Thymic peptide thymosin ₁ (10^–9 to 3 x 1010^–7 M) is shown to inhibit the specific binding of [¹²⁵I]VIP to rat blood mononuclear cells and liver plasma membranes. Thymosin ₁ was 160 and 6250 times less potent that VIP at inhibiting [¹²⁵I]VIP binding to blood mononuclear cells and liver plasma membranes, respectively. Thymosin ₁ (10^–10 to 1010^–7 M) was weak in stimulating adenylate cyclase activity. Its efficacy is about 25 % and 27 % that of native VIP in blood mononuclear cells and liver plasma membranes, respectively. Thymosin ₁ may behave as a partial VIP agonist in rat.Abbreviations GRF growth hormone releasing factor - PHI porcine intestinal peptide having N-terminal histidine and C-terminal isoleucine amide - GIP gastric inhibitory polypeptide - VIP vasoactive intestinal peptide     

Genetic polymorphism at the mouse immunoglobulin J ϰ locus (Igk-J) as demonstrated by southern hybridization and nucleotide sequence analysis

Comparison of the nucleotide sequences of the C.C58 M75 myeloma chain gene and the BALB/c germ-line J segments suggested that the J regions of C.C58 and BALB/c might be distinguished by restriction enzyme polymorphisms. This was shown to be the case in Southern hybridizations of Hinf I and Ace I digests of liver DNA from these and other strains with a J-specific probe. Tests of a wide variety of inbred, congenic, recombinant, and recombinant-inbred strains provided evidence for three alleles, Igk-J ^a, Igk-J ^b, and Igk-J ^c, the type strains for which are C58/J, BALB/c, and SJL/J, respectively. Analysis of the B6.PL(85NS) congenic strain suggests that the Igk-J locus lies in the neighborhood of the Lyt-2/Lyt-3 loci, approximately 0.30 cM from the V gene segment determining the Igk-VSer and Igk-Efl polymorphisms. Finally, nucleotide substitutions lead to amino acid sequence differences between the C.C58 M 75 gene and the BALB/c germ line in J2 and J4. Two of these substitutions reflect true germ-line differences, raising the possibility that idiotype differences observed among strains could reflect J as well as V differences.     

The underwater light field in the Bellingshausen and Amundsen Seas (Antarctica)

The underwater light field in the Bellingshausen andAdmundsen Seas was characterised using data collectedduring the R/V Polarstern cruise ANT XI/3, from12.1.94 to 27.3.94. The euphotic zone varied from 24to 100 m depth. Spectral diffuse vertical attenuationcoefficients (K _d ())were determined for 12narrow wavebands as well as for photosyntheticallyavailable radiation (PAR, 400–700 nm): K _d (490)ranged from 0.03 to 0.26 m¹; K _d (550) from0.04 to 0.17 m¹; K _d (683) from 0.04 to0.17 m¹; and K _d (PAR) varied from 0.02 to0.25 m¹. K _d () for wavelengths centred at412 nm, 443 nm, 465 nm, 490 nm, 510 nm, 520 nm and550 nm were significantly correlated with chlorophyllconcentration (ranging from 0.1 to 6 mg m³). Thevertical attenuation coefficients for 340 nm and380 nm ranged from 0.10 to 0.69 m¹ and from 0.05to 0.34 m¹, respectively, and were also highlycorrelated with chlorophyll concentrations. These K _d values indicate that the 1% penetration depthmay reach maxima of 46 m and 92 m for 340 nm and380 nm, respectively. The spectral radiancereflectances (Rr()) for 443 nm, 510 nm and 550 nmwere less than 0.01 sr¹. Rr() for 665 nm and683 nm increased with depth up to 0.2 sr¹ because ofchlorophyll fluorescence. Using a model that predicts downwardirradiances by taking into account the attenuation bywater and absorption by chlorophyll, we show thatchlorophyll fluorescence has a significant influenceon the red downward irradiance (E _d (633, 665, 683))in deeper layers. The ability of the phytoplanktonpopulation to influence the light environment byautofluorescence and absorption processes depends onthe light conditions and on the photoacclimation ofthe cells, represented by the in vivo crosssection absorption coefficient of chlorophyll (a*). Theobtained mean chlorophyll-specific light attenuationcoefficients of phytoplankton in situ (k _d ) are higherthan the in vivo absorption coefficient of chlorophyll,more than to be excepted from the scattering. a*(), m² mg chl¹, decreased due topackaging effect with increasing chlorophyllconcentrations.     

Analysing the responses of photosynthetic CO2 assimilation to long-term elevation of atmospheric CO2 concentration

Understanding how photosynthetic capacity acclimatises when plants are grown in an atmosphere of rising CO₂ concentrations will be vital to the development of mechanistic models of the response of plant productivity to global environmental change. A limitation to the study of acclimatisation is the small amount of material that may be destructively harvested from long-term studies of the effects of elevation of CO₂ concentration. Technological developments in the measurement of gas exchange, fluorescence and absorption spectroscopy, coupled with theoretical developments in the interpretation of measured values now allow detailed analyses of limitations to photosynthesisin vivo. The use of leaf chambers with Ulbricht integrating spheres allows separation of change in the maximum efficiency of energy transduction in the assimilation of CO₂ from changes in tissue absorptance. Analysis of the response of CO₂ assimilation to intercellular CO₂ concentration allows quantitative determination of the limitation imposed by stomata, carboxylation efficiency, and the rate of regeneration of ribulose 1:5 bisphosphate. Chlorophyll fluorescence provides a rapid method for detecting photoinhibition in heterogeneously illuminated leaves within canopies in the field. Modulated fluorescence and absorption spectroscopy allow parallel measurements of the efficiency of light utilisation in electron transport through photosystems I and IIin situ.Abbreviations A net rate of CO₂ uptke per unit leaf area (µmol m^–2 s^–1) - A_sat light-saturated A - A₈₂₀ change in absorptance of PSI on removal of illumination (OD) - c CO₂ concentration in air (µmol mol^–1) - c_a c in the bulk air; c_i, c in the intercellular spaces - ce carboxylation efficiency (mol m^–2 s^–1) - E transpiration per unit leaf area (mol m^–2 s^–1) - F fluorescence emission of PSII (relative units) - F_m maximal level of F - F_o minimal level of F upon illumination when PSII is maximally oxidised - F_s the steady-state F following the m peak - F_v the difference between F_m and F_o - F'_m maximal F' generated after the m peak by addition of a saturating light pulse - F'_o the minimal level of F' after the m peak determined by re-oxidising PSII by far-red light - g₁ leaf conductance to CO₂ diffusion in the gas phase (mol m^–2 s^–1) - g'₁ leaf conductance to water vapour diffusion in the gas phase (mol m^–2 s^–1) - k_c and k_o the Michaelis constants for CO₂ and O₂, respectively, (µmol mol^–1); - J_max the maximum rate of regeneration of rubP (µmol m^–2 s^–1) - l stomatal limitation to CO₂ uptake (dimensionless, 0–1) - LCP light compensation point of photosynthesis (µmol m^–2 s^–1) - o_i the intercellular O₂ concentration (mmol mol^–1) - Pi cytosol inorganic phosphate concentration - PSI photosystem I - PSII photosystem II - Q photon flux (µmol m^–2 s^–1) - Q_abs Q absorbed by the leaf - rubisCO ribulose 1:5 bisphosphate carboxylase/oxygenase; rubP, ribulose 1:5 bisphosphate; s, projected surface area of a leaf (m²) - V_c,max is the maximum rate of carboxylation (µmol m^–2 s^–1) - W_c the rubisCO limited rate of carboxylation (µmol m^–2 s¹) - W_j the electron transport limited rate of regeneration of rubP (µmol m^–2 s^–1) - W_p the inorganic phosphate limited rate of regeneration of rubP (µmol m^–2 s^–1) - absorptance of light (dimensionless, 0–1) - _a of standard black absorber ₁, of leaf - _s of integrating sphere walls - , CO₂ compensation point of photosynthesis (µmol mol^–1) - the specificity factor for rubisCO carboxylation (dimensionless) - , convexity of the response of A to Q (dimensionless 0–1) - the quantum yield of photosynthesis on an absorbed light basis (A/Q_abs; dimensionless) - the quantum yield of photosynthesis on an incident light basis (A/Q; dimensionless) - _app the maximum - _m the maximum - _m,app the photochemical efficiency of PSII (dimensionless, 0–1) - _PSII,m the maximum      

Oligoadenylates formation on an oligouridylate template in the presence of a lead catalyst

Summary Oligouridylates with more than eight chain units can serve as a template for the template-directed condensation of ImpA catalyzed by Pb²⁺ ion. The templates and the Pb²⁺ ion catalyst facilitate the formation of longer oligoadenylates with five or more units. The ratio of 3–5 linked oligomers to the 2–5 isomers increases with increasing chain length of the oligouridylate template. Short oligouridylates up to a hexamer tend to decrease the yield of oligoadenylates, and do not affect the selectivity of internucleotide linkage.Abbreviations EDTA ethylenediaminetetracetic acid - Tris tris(hydroxymethyl)aminomethane - A adenosine - ImpA adenosine 5-phosphorimidazolide - pA adenosine 5-phosphate - Ap adenosine 2(3)-phosphate - poly A polyadenylic acid - AppA P₁,P₂-diadenosine 5-diphosphate - pAp adenosine 2(3),5-diphosphate - ApA adenylyl adenosine - (pA)_n (n = 2,3,) oligomers of pA - ImpApA 5-phosphorimidazolide of ApA - U uridine - pU uridine 5-phosphate - Up uridine 2(3)-phosphate - poly U polyuridylic acid - pUp uridine 2(3),5-diphosphate - (pU)_n (n = 2,3,) oligomers of pU - (pU)_n – (pA)_m cooligomers composed of (pU)_n and (pA)_m units - AppUpUpUpUp pyrophosphate derived from pA and (pU)₄ - AppUp P₁-(adenosine 5)-P₂-(uridine 2(3)-phosphate 5) -pyrophosphate - BAP bacterial alkaline phosphatase - VPD venom phosphodiesterase - N.P₁ nuclease P₁ - RNase A pancreatic ribonuclease - A^* radioactive adenosine     

The mitochondrial membrane potential (deltapsi(m)) in apoptosis; an update

Mitochondrial dysfunction has been shown to participate in the induction of apoptosis and has even been suggested to be central to the apoptotic pathway. Indeed, opening of the mitochondrial permeability transition pore has been demonstrated to induce depolarization of the transmembrane potential (_m), release of apoptogenic factors and loss of oxidative phosphorylation. In some apoptotic systems, loss of _m may be an early event in the apoptotic process. However, there are emerging data suggesting that, depending on the model of apoptosis, the loss of _m may not be an early requirement for apoptosis, but on the contrary may be a consequence of the apoptotic-signaling pathway. Furthermore, to add to these conflicting data, loss of _m has been demonstrated to not be required for cytochrome c release, whereas release of apoptosis inducing factor AIF is dependent upon disruption of _m early in the apoptotic pathway. Together, the existing literature suggests that depending on the cell system under investigation and the apoptotic stimuli used, dissipation of _m may or may not be an early event in the apoptotic pathway. Discrepancies in this area of apoptosis research may be attributed to the fluorochromes used to detect _m. Differential degrees of sensitivity of these fluorochromes exist, and there are also important factors that contribute to their ability to accurately discriminate changes in _m.     

The Effect of Tetrazole and Its Amino Derivatives on the Kinetics of Peroxidase Oxidation of Chromogenic Substrates

The peroxidase-catalyzed oxidation of 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), o-phenylenediamine (PDA), and 3,3,5,5-tetramethylbenzidine (TMB) was found to be activated by tetrazole and 5-aminotetrazole (AT) and weakly inhibited by 1,5-diaminotetrazole. The activating action of tetrazole and AT on the PDA and TMB oxidation was clearly discompetitive and that on ABTS was non-competitive. The coefficients (degrees) of activation were determined for three substrates and two activators; they depended on the substrate type and the buffer nature and increased along with the pH growth from 6.4 to 7.2. For AT and tetrazole, the maximal values were 4140 and 800 M^–1, respectively, upon the PDA oxidation and 3570 and 540 M^–1, respectively, upon the TMB oxidation. Lower values (145 and 58 M^–1 for tetrazole and AT, respectively) were characteristic of the peroxidase oxidation of ABTS. The activation of peroxidase oxidation of the substrates by tetrazole and AT at pH 5.4 was explained by the nucleophilic nature of the activators interacting with the amino acid residues in the peroxidase active site according to the mechanism of acid–base catalysis.     

Cucumber mosaic virus RNA contains 7-methyl guanosine at the 5′-terminus of all four RNA species

Purified cucumber mosaic virus (CMV) RNA was reacted with NaIO₄ and then [³H]KBH₄ to label ends containing exposed 2,3-hydroxyls. The four major RNA species were then fractionated by polyacrylamide gel electrophoresis. Analysis of digests of these RNAs by ribonucleases T1 plus T2, alkaline phosphatease, snake venom diesterase and nucleotide pyrophosphatase by means of paper electrophoresis and ion-exchange chromatography indicated that the sequence m⁷G(5)ppp(5)N was present at the 5-end of 75–92% of all RNA molecules. In addition, about 90% of the 3-ends terminated in either adenosine or cytidine.     

The relation of proton motive force,adenylate energy charge and phosphorylation potential to the specific growth rate and efficiency of energy transduction inBacillus licheniformis under aerobic growth conditions

The magnitude of the proton motive force (p) and its constituents, the electrical () and chemical potential (-ZpH), were established for chemostat cultures of a protease-producing, relaxed (rel ^–) variant and a not protease-producing, stringent (rel ⁺) variant of an industrial strain ofBacillus licheniformis (respectively referred to as the A- and the B-type). For both types, an inverse relation of p with the specific growth rate was found. The calculated intracellular pH (pH_in) was not constant but inversely related to . This change in pH_in might be related to regulatory functions of metabolism but a regulatory role for pH_in itself could not be envisaged. Measurement of the adenylate energy charge (EC) showed a direct relation with for glucose-limited chemostat cultures; in nitrogen-limited chemostat cultures, the EC showed an approximately constant value at low and an increased value at higher . For both limitations, the ATP/ADP ratio was directly related to .The phosphorylation potential (G'p) was invariant with . From the values for G'p and p, a variable H⁺/ATP-stoichiometry was inferred: H⁺/ATP=1.83+0.52µ, so that at a given H⁺/O-ratio of four (4), the apparent P/O-ratio (inferred from regression analysis) showed a decline of 2.16 to 1.87 for =0 to _max (we discuss how more than half of this decline will be independent of any change in internal cell-volume). We propose that the constancy of G'p and the decrease in the efficiency of energy-conservation (P/O-value) with increasing are a way in which the cells try to cope with an apparent less than perfect coordination between anabolism and catabolism to keep up the highest possible with a minimum loss of growth-efficiency. Protease production in nitrogen-limited cultures as compared to glucose-limited cultures, and the difference between the A- and B-type, could not be explained by a different energy-status of the cells.Abbreviations CCCP carbonylcyanide-p-trichloromethoxyphenylhydrazone - DW dry weight of biomass - F Faraday's constant, 96.6 J/(mV × mol) - Fo chemostat outflow-rate (ml/h) - FCCP carbonylcyanide-p-trifluoromethoxyphenylhydrazone - G'p phosphorylation potential, the Gibbs energy change for ATP-synthesis from ADP and P_i - G'⁰p standard Gibbs energy change at specified conditions - H⁺/ATP number of protons translocated through - ATP synthase in synthesis of one ATP - H⁺/O protons translocated during transfer of 2 electrons from substrate to oxygen - specific growth rate (1/h) - _H+ transmembrane electrochemical proton potential, J/mol - M_b molar weight (147.6 g/mol) of bacteria with general cell formula C_6.0H_10.8O_3.0N_1.2 - pH_out,in extracellular, intracellular pH - P_i (intracellular) inorganic phosphate - p proton motive force, mV - pH transmembrane pH-difference - transmembrane electrical potential, mV - P/O number of ADP phosphorylated to ATP upon reduction of one O^2– to H₂O by two electrons transferred through the electron transfer chain - P/O (H⁺/O) × (H⁺/ATP)^–1 - P/O_F, P/O_N P/O with the two electrons donated by resp. (NADH + H⁺) and FADH - q specific rate of consumption or production (mol/g DW × h) - rel ⁺,rel ^– stringent, relaxed genotype - R universal gas constant, 8.36 J/(mol × degree) - T absolute temperature - TPMP⁺ triphenylmethylphosphonium ion - TPP⁺ tetraphenyl phosphonium ion - Y growth yield, g DW/mol - Z conversion constant=61.8 mV for 310 K (37 °C) - ZpH transmembrane proton potential or chemical potential, mV     

Calculations of one-, two- and three-bond nuclear spin-spin couplings in a model peptide and correlations with experimental data

Summary We present ab initio calculations of the Fermi contact term and experimental correlations of six coupling constants, ³J_H ^N _H , ¹J_{C H} , ²J_CH , ¹J_{C N}, ²J_{C N} and ¹J_CN, in a peptide as functions of the backbone dihedral angles, and . Given estimates of experimental uncertainties, we find semiquantitative experimental correlations for ³J_H ^N _H , ¹J_{C N} and ²J_{C N}, qualitative correlations for ¹J_{C H} and ²J_CH , but no experimental correlations of practical utility for ¹J_CN, owing to its complex dependence on at least four dihedral angles. Errors in the estimation of dihedral angles from X-ray crystallographic data for proteins, which result from uncertainties in atom-to-atom distances, place substantial limitations on the quantitative reliability of coupling constant calculations fitted to such data. In the accompanying paper [Edison, A.S. et al., J. Biomol. NMR, 4, 543–551] we apply the results of the coupling constant calculations presented here to the estimation of and angles in staphylococcal nuclease from experimental coupling constants.Abbreviations AO atomic orbital - BPTI basic pancreatic trypsin inhibitor (bovine) - CI-2 chymotrypsin inhibitor 2 - E.COSY exclusive correlation spectroscopy (Griesinger et al., 1986) - ⁿJ_AB single bond (n=1), geminal (n=2), or vicinal (n=3) coupling constant between nuclei A and B - LCAO linear combination of atomic orbitals - NBO natural bond orbital - n lone pair orbitals - bonding orbitals - ^* antibonding orbitals - dihedral angle or molecular orbital wave function; r², correlation coefficient - RHF restricted Hartree-Fock; rmsd, root-mean-square deviation - 3-21G and 6-31G^* molecular orbital basis set designations (Hehre et al., 1986)     

Molecular cloning of phenylalanine ammonia-lyase cDNA and classification of varieties and cultivars of tea plants (Camellia sinensis) using the tea PAL cDNA probe

Tea (Camellia sinensis) phenylalanine ammonia-lyase (PAL) cDNA was cloned using labelled rice PAL cDNA as a probe. The PAL genes of the tea plant were investigated by restriction fragment length polymorphism (RFLP) analysis using tea PAL cDNA. PAL genetic variation in tea plants was much larger than predicted due to the presence of various hybridized fragments in the Assam hybrids, which are hybrids between C. sinensis var assamica and var sinensis. On the other hand, hybridized band patterns of Japanese green tea cultivars belonging to var sinensis could be divided into five groups. Furthermore, a short-length PAL probe, about 280 bp including the 3 untranslated sequence, detected 3 DNA fragments of different lengths, which were named A, B and D. An experiment tracing the PAL gene heredity showed that A, B and D fragments were inherited according to the Mendelian monogenic ratio. Therefore, PAL genes identifiable by A, B and D fragments are multiple alleles, and the PAL gene is present as a single gene in the tea haploid genome. It was also clear that five groups of Japanese green tea cultivars were characterized by the composition of these PAL fragments. From RFLP analysis using tea PAL cDNA, we succeeded in distinguishing Assam hybrids and Japanese green tea cultivars with high and low catechin content, respectively, and in grouping Japanese green tea at the cultivar level.     

Ganglioside-cholera toxin interactions: a binding and lipid monolayer study

Summary On t.l.c. plates ¹²⁵I-cholera toxin binds to a disialoganglioside tentatively identified as GD_lb with about 10 times less capacity than to ganglioside GM₁. Binding of labeled toxin to both gangliosides was abolished in presence of excess amounts of unlabeled B subunit. Ganglioside extracts from human or pig intestinal mucosa showed toxin binding to gangliosides GM₁ and GD_1b. In ganglioside-containing lipid monolayers the penetration of the toxin was independent of the ganglioside binding capacity.Abbreviations GM₂ Gal-NAc14Gal(3-2NeuAc)14G1c1Cer - GM₁ Gal3Ga1-NAc14Gal(32NeuAc)14G1c11Cer - GD_1a NeuAc23Ga113Gal-NAc14Gal(32NeuAc)14G1c11Cer - GD1b Gall3Gal-NAcl4Gal(32NeuAc82NeuAc)14Glc11Cer - GT_1b NeuAc23Ga113Ga1-NAcal4Gal(3-2NeuAc82NeuAc)14G1c11Cer - dpPC 1,2-hexadecanoyl-sn-glycero-3-phosphocholine - dpPE 1,2-hexadecanoyl-sn-glycero-3-phosphoethanolamine     

Endothelin-1 and insulin induce cellular inactivation of protein kinase FA/glycogen synthase kinase-3α in a common signaling pathway

In this study, we investigate the effects of endothelin-1 (ET-1) and insulin on the cellular activity of protein kinase F_A/glycogen synthase kinase-3 (kinase F_A/GSK-3) in rat adipocytes. The cellular activity of kinase F_A/GSK-3 is inhibited to 50% of control within 30 min when cells are treated with 1 nM ET-1 at 37°C; in addition, significant inhibition to 60% of control is observed at as low as 1 pM ET-1. Conversely, ET-1 at concentrations up to 1 nM has no direct effect on purified kinase F_A/GSK-3 in vitro. Immunoblotting analysis further reveals that the protein level of this kinase is not significantly changed when treated with 1 nM ET-1 for 30 min. Similar to ET-1, insulin as low as 10 nM can also induce inactivation of kinase F_A/GSK-3 to 50% of control in adipocytes when processed under identical conditions. Most importantly, when treated with both insulin and ET-1, the activity of kinase F_A/GSK-3 can be decreased only to 50% of control. Taken together, the results provide initial evidence that ET-1 and insulin may regulate this important multisubstrate/multifunctional protein kinase in a common signaling pathway in cells.     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

Analogues of NADP+ as inhibitors and coenzymes for NADP+ malic enzyme from maize leaves

Structural analogues of the NADP⁺ were studied as potential coenzymes and inhibitors for NADP⁺ dependent malic enzyme from Zea mays L. leaves. Results showed that 1, N⁶-etheno-nicotinamide adenine dinucleotide phosphate ( NADP⁺), 3-acetylpyridine-adenine dinucleotide phosphate (APADP⁺), nicotinamide-hypoxanthine dinucleotide phosphate (NHDP⁺) and -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate (23NADPc⁺) act as alternate coenzymes for the enzyme and that there is little variation in the values of the Michaelis constants and only a threefold variation in V_max for the five nucleotides. On the other hand, thionicotinamide-adenine dinucleotide phosphate (SNADP⁺), 3-aminopyridine-adenine dinucleotide phosphate (AADP⁺), adenosine 2-monophosphate (2AMP) and adenosine 2: 3-cyclic monophosphate (23AMPc) were competitive inhibitors with respect to NADP⁺, while -nicotinamide adenine dinucleotide 3-phosphate (3NADP⁺), NAD⁺, adenosine 3-monophosphate (3AMP), adenosine 2: 5-cyclic monophosphate (25AMPc), 5AMP, 5ADP, 5ATP and adenosine act as non-competitive inhibitors. These results, together with results of semiempirical self-consistent field-molecular orbitals calculations, suggest that the 2-phosphate group is crucial for the nucleotide binding to the enzyme, whereas the charge density on the C₄ atom of the pyridine ring is the major factor that governs the coenzyme activity.Abbreviations NADP⁺ 1, N⁶-etheno-nicotinamide adenine dinucleotide phosphate - NHDP⁺ nicotinamide-hypoxanthine dinucleotide phosphate - APADP⁺ 3-acetylpyridine-adenine dinucleotide phosphate - SNADP⁺ thionicotinamide-adenine dinucleotide phosphate - AADP⁺ 3-aminopyridine-adenine dinucleotide phosphate - 23NADPc⁺ -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate - 3NADP⁺ -nicotinamide adenine dinucleotide 3-phosphate - 2AMP adenosine 2-monophosphate - 3AMP adenosine 3-monophosphate - 23AMPc adenosine 2: 3 monophosphate cyclic - A adenosine - RuBP ribulose 1,5-bisphosphate - SCF-MO Self-Consistent Field-Molecular Orbitals (method)     

Conformational energy of the 5-membered ring. Implication of geometric and energetic properties in the conformational characteristics

In a previous article (8) a geometrical study of the five-membered ring showed that: a) for the case of the 20 symmetrical C₂ and C_s conformations, the pseudorotation formulae for the torsion angles are a geometrical property of the ring; b) geometrical considerations alone are unable to define the puckering amplitude, the bond angle values, and the pathway between two symmetrical conformations. Here we examine how the energy equations enable us to define the deformation amplitude _m, establish the bond angles expressions and check the energy invariability along the pseudorotation circuit. The problem is next developed fully in the case where the bond and torsional energy only are considered: the literal expression¹ of _m is then given as a function of the bond angle which cancels out the bond angle energy. A numerical application is carried out on cyclopentane and the values of the parameters K^t, K¹ and used in the Conformational energy calculations are considered.Notations used 1 _i bond lengths 1 in the case of the regular ring - _i torsional angles - _i bond angles - 3/5 = 108 - 4/5 = 144 - , _{i i} – = complement to the 108 bond angle _i - _T - E Conformational energy of the 5-membered ring - E Conformational energy difference between planar and deformed ring - A _n Coefficients of the energy development in terms of - E _i ^l Bond energy relative to atom i (associated with angle _i) - K _i ^l Bond constant relative to atom i (associated with angle _i) - E _i ^l Torsional energy relative to the i ^th bond (associated with angle _i) - k _i ^l Torsional constant relative to the i ^th bond (associated with angle _i) - _i Angle _i value corresponding to zero bond energy E _i ^l (when the 5 atoms of the ring are identical, _i ) - r _ij Distance between atoms i and j - q _i Charge carried by atom i - e Constant of proportionality including the effective dielectric constant - A _ij, B_ij, d_ij Coefficients dependent on the nature of the atoms i and j and accounted for in the Van der Waals energy and hydrogen bond expressions - S (r _ij) Electrostatic contribution to the hydrogen bond energy - P Pseudorotation phase angle - _m Maximum torsional angle value characterising the deformation amplitudeM     

Life tables of Moina macrocopa (Straus) in successive generations under food and temperature adaptation

Life tables of Moina macrocopa (Straus) cultured at seven foodconcentrations (FC) (Scenedesmus sp., 1.49–1490 mg wet weightl^-1, 10⁴–10⁶ cellml^-1) were investigated for animals of the first generation(nonadapted animals) and for animals of the third generation (adaptedanimals) cultivated at these FC. Adapted animals showed a trophicpreferendum, i.e. a narrow FC-range at which maximal R_ovalues were observed in comparison with nonadapted animals. In adaptedanimals, the maximal R_o was 115.3 individual, observed at 20°C and a FC of 74.5 mg wet weight l^-1.     

Measurement of residual dipolar couplings from 1Hα to 13Cα and 15N using a simple HNCA-based experiment

Novel NMR pulse schemes for simultaneous measurement of ¹ D _CHand ² D _NHresidual dipolar couplings in proteins is presented. We show that ² D _NHcoupling can be very useful for protein structure determination. The ² D _NHcoupling can be measured from ¹⁵N dimension with good accuracy on a slowly relaxing TROSY resonance, utilizing HNCA-TROSY-based experiments, which concomitantly supply large ¹ D _CHcoupling. The dynamic range of ² D _NHcoupling is comparable to ¹ D _NC coupling, but instead, it also serves non-redundant information on the course of protein backbone, thanks to rotational degree of freedom with respect to peptide bond. The HNCA-TROSY-based experiments are optimal for measuring residual dipolar couplings at high magnetic fields owing to absence of rapid transverse relaxation of carbonyl carbon. The reliability of the proposed approach was tested on ¹⁵N/¹³C human ubiquitin. A very good correlation with ubiquitin solution as well as crystal structure, for both ¹ D _CHand ² D _NHcouplings, was obtained.     

Black alder (Alnus Glutinosa (L.) Gaertn.) trees mediate methane and nitrous oxide emission from the soil to the atmosphere

Three-year-old seedlings of black alder (Alnus glutinosa (L.) Gaertn.), a common European wetland tree species, were grown in native soil taken from an alder swamp. Fluxes of methane (CH₄) and nitrous oxide (N₂O) between the tree stem and the atmosphere were determined under controlled conditions. Both CH₄ and N₂O were emitted through the bark of the stem into the atmosphere when the root zone exhibited higher-than-ambient CH₄ and N₂O gas mixing ratios. Flooding of the soil caused a decreased N₂O emission but an increased CH₄ efflux from the stem. Immediately after flooding of the soil, N₂O was emitted from the seedlings' bark at a rate of 350 mol N₂O m^-2 h^-1 whereas CH₄ flux could not be detected. After more than 40 days of flooding CH₄ fluxes up to 3750 mol CH₄ m^-2 h^-1 from the stem were measured, while N₂O emission had decreased below the limit of detection. Gas efflux decreased with increasing stem height and correlated with gas mixing ratios in the soil, indicating diffusion through the aerenchyma as the major path of gas transport. From these results it is assumed that woody species with aerenchyma can serve as conduits for soil-derived trace gases into the atmosphere, to date only shown for herbaceous plants. This, yet unidentified, woody plant pathway contributes to the total greenhouse gas source strength of wetlands.