Adenylylsulfate reductase in some new sulfate-reducing bacteria

Four recently described species of new genera of sulfate-reducing bacteria, Desulfobulbus propionicus, Desulfobacter postgatei, Desulfococcus multivorans and Desulfosarcina variabilis were examined with respect to adenylylsulfate reductase. All of the species examined contained the enzyme in sufficient concentrations to account for dissimilatory sulfate reduction.Adenylylsulfate reductase was enriched 17.1-fold from Desulfobulbus propionicus by ammonium sulfate fractionation, ion exchange chromatography and gel filtration. The molecular weight was 175,000 and the enzyme contained 1 mol of flavin, 8 mol of non heme iron and 8 mol of labile sulfide per mol enzyme. Either ferricyanide or cytochrome c could be used as electron acceptors; the pH optimum was 7.7 with ferricyanide and 8.8 with cytochrome c. K _m values for AMP and sulfite were 90 M and 1.3 M with ferricyanide and 91 M and 71 M with cytochrome c as electron acceptor. K _m values for ferricyanide and cytochrome c were 89 M and 21 M, respectively. The properties of the enzyme were compared with those of purified adenylylsulfate reductases from other microorganisms.Non-common abbreviation APS adenylylsulfate     

Microbial sensors for determination of aromatics and their chloro derivatives. Part III: Determination of chlorinated phenols using a biosensor containing Trichosporon beigelii (cutaneum)

An amperometric biosensor for the determination of phenol and chlorophenols using Trichosporon beigelii (cutaneum) has been developed. This sensor is more sensitive to chlorophenols, especially to mono- and dichlorinated phenols, than to phenol and is insensitive to benzoate. A linear relationship between the current range and the concentration of 4-chlorophenol is observed up to 40 mol/l. The detection limit for all substrates studies is 2 mol/l. the current difference is reproducible within 5.5% when the test solution contains 0.40 mol 4-chlorophenol.     

Development of high frequency multiple shoot formation in Persian clover (<Emphasis Type="Italic">Trifolium resupinatum</Emphasis> L.)

An efficient and reliable micropropagation system for Persian clover (Trifolium resupinatum L.) was developed using different explants and media. Node, hypocotyl and cotyledonary node explants were cultured on Murashige and Skoog (MS) medium supplemented with combinations of either 6-benzyladenine (BA) and indole-3-butyric acid (IBA) or BA, Kinetin (KIN) and IBA. Direct multiple shoots developed within 6weeks in all explants in most media tested. The best shoot multiplication capacity was obtained from cotyledonary node explants on MS medium containing 7.1M BA and 1M IBA or 14.1M BA and 1M IBA. Elongated shoots were rooted on either MS medium alone or combination with different concentrations of indole-3-butyric acid (IBA), indole-3-acetic acid (IAA) and -naphthaleneacetic acid (NAA). High rooting was achieved in half strength MS medium containing 8M IBA.     

An alternative propagation method ofAnanas through nodule culture

A micropropagation scheme forAnanas comosus Merr. was developed using nodule culture. Nodules were induced from leaf-base or chopped shoot-base explants on modified half-strength MS medium supplemented with 2.69-5.37 M NAA and 4.44 M BA and could be maintained long-term as nodules. The nodules proliferated into more nodules when chopped into pieces of 1–3 mm and placed onto the same medium. They regenerated shoots when transferred to medium supplemented with 0.54–10.74 M NAA and 0.44–8.88 M BA. The regeneration capacity of nodules is higher than that of direct regeneration or callus. Maximum regeneration was obtained from culture medium containing 0.54 M NAA and 0.44 M BA, where shoots could be observed as early as within 2 weeks. Many shoots formed roots in the same medium in which they were regenerated after 10 subcultures, but the best rooting occurred in medium containing 0.54 M NAA and 0.44 M BA. Rooted plantlets ofA. comosus Merr. could be routinely produced at 6-week intervals.Abbreviations NAA naphthaleneacetic acid - BA 6-benzylaminopurine     

Characterization of catecholamine uptake2 in isolated cardiac myocytes

Extraneuronal catecholamine uptake was investigated in isolated quiescent rat myocardial cells. By administration of (³H-)(–)noradrenaline concentration of 22 nmol/l up to 1000 mol/l the following data were obtained: (1) The K_M of the uptake process amounted to 260 mol/l, the V_max to 4.24 nmol/(10 min × mg Protein) corresponding to 179 nmol/(min × g_WWt)(WWT = Wet Weight). (2) The uptake was largely inhibited by the uptake₂-inhibitors corticosterone (100 mol/l), isoprenaline (IC so = 30.6 mol/l), and O-methylisoprenaline (IC₅₀ = 2.1 pmol/l), but not by the uptake₁-inhibitors cocaine (100 mol/l) and desipramine (10 mol/l). (3) The affinity-values K_M and IC₅₀ closely agreed with those already known, but the V_max-value was higher than those obtained in whole rat hearts by a factor of at least 1.79. This is caused presumably by the voltage dependence of the uptake mechanism and the resulting inhibition of uptake 2 during the periods of depolarisation in beating hearts of other studies.     

Adventitious shoot formation and plant regeneration from tissues of tomatillo (Physalis ixocarpa Brot.)

Cultured hypocotyl explants of tomatillo (Physalis ixocarpa Brot.), were evaluated with regard to their morphogenic responses to combinations of benzyladenine (BA, 0–5 M) with either naphthaleneacetic acid (NAA, 0–50 M) or 2,4-dichlorophenoxyacetic acid (2,4-D, 0–50 M). The induction of shoots or roots was dependent on the cytokinin/auxin combination.Hypocotyl explants failed to form shoots when they were grown on media containing either a cytokinin or an auxin alone. The highest frequency of shoot formation was observed on media containing 12.5–25 M BA and 5 M NAA. Likewise the highest frequency of root formation was observed on media supplemented with 1 M BA and 1 M NAA. Complete plants were regenerated and transferred to soil, where they reached maturity.     

Genes of the constant regions of functional immunoglobulin heavy chain of Japanese flounder,<Emphasis Type="Italic"> Paralichthys olivaceus</Emphasis>

IgM and IgD genes of the Japanese flounder were cloned and characterized from a genomic bacterial artificial chromosome (BAC) library. The gene contained four constant region exons (C1–C4), and two transmembrane exons (TM1 and TM2), which conforms to the organizational pattern of all other vertebrate -chain genes examined so far. In the same BAC clone, the gene, which is homologous to the IgD gene in mammals and teleost fish, was found immediately (0.9 kb) downstream of the IgM gene. This gene encoded seven exons (C1–C7) and two TM exons (TM1 and TM2) and had no duplication of C1-C2, as found in Atlantic cod, or C2-C3-C4, as found in Atlantic salmon and channel catfish. Phylogenetic and sequence analyses strongly suggest that teleost is more closely related to non-IgM isotypes than IgM isotypes. The heavy chain (IgH) locus of Japanese flounder, which encodes m, s and m, was found to be fully functional.     

Accumulation of silver by growing and non-growing populations of Citrobacter intermedius B6

Summary Accumulation of silver is reported for growing and non-growing populations of Citrobacter intermedius B6. In non-growing cultures a maximum uptake of 4.35% (w/w) was observed at an initial silver concentration of 2111.2 mol Ag⁺ l^-1. In contrast the maximum uptake of silver by growing bacteria was 2.81% (w/w) at an effective concentration of silver of 217.8 mol·l^-1. Silver accumulation rates in both resting (460 mol Ag⁺ g^-1 per hour) and continuously grown (41 mol Ag⁺ g^-1 per hour) bacteria are higher than previously reported. Cell fractionation and electron microscopy of continuously grown bacteria indicated that accumulation of silver was associated with the cell envelope, in the form of dense deposits of macromolecular proportions. This observation discounts simple surface adsorption as the process of accumulation in growing cultures.     

Effects of GNA and other mannose binding lectins on development and fecundity of the peach-potato aphid Myzus persicae

Three mannose-binding lectins were assayed in artificial diets for their toxic and growth-inhibitory effects on nymphal development of the peach-potato aphid Myzus persicae. The snowdrop (Galanthus nivalis) lectin GNA was the most toxic, with an induced nymphal mortality of 42% at 1500 g ml^–1 (30 M) and an IC₅₀ (50% growth inhibition) of 630 g ml^–1 (13 M). The daffodil (Narcissus pseudonarcissus) lectin NPA and a garlic (Allium sativum) lectin ASA induced no significant mortality in the range 10–1500 g ml^–1, but did result in growth inhibition of 59% (NPA) and 26% (ASA) at 1500 g ml^–1 (40 M for NPA, 63 M for ASA). All three lectins were responsible for a slight but significant growth stimulation when ingested at 10 g ml^–1, reaching +26%, +18% and +11% over the control values for the garlic lectin, the daffodil lectin and the snowdrop lectin, respectively. GNA, as well as the glucose/mannose binding lectin Concanavalin A, were also provided at sublethal doses throughout the life cycle of the aphids, and effects on adult performance were monitored. Adult survival was not significantly altered, but both lectins adversely affected total fecundity and the dynamics of reproduction, resulting in significant reduction in calculated r _ms (population intrinsic rate of natural increase) on lectin-containing diets. These effects are discussed in relation to the use of transgenic plants expressing these toxic lectins for potential control of aphid populations.     

Methylmercury-injury effect on tube formation by cultured human vascular endothelial cells

The effect of methylmercury chloride (MeHg) on growth and tube formation by cultured human umbilical vein endothelial cells (HUVECs) was investigated. HUVECs were collected by enzymatic digestion with collagenase. Precultivation of HUVECs with MeHg at concentrations of 1.0–50.0 mol/L exerted negligible effects on the viable cell number, while the viable cell number was slightly reduced at 100 mol/L and fell to zero at concentrations exceeding 500.0 mol/L MeHg. The viable cell number was depressed in a concentration-dependent manner. Tube formation was studied by culturing the cells on gelled basement membrane matrix (Matrigel). Treatment of HUVECs with 0.1–5.0 mol/L MeHg for 24 h inhibited tube formation dose-dependently. Fetal bovine serum (FBS) increased tube formation in a dose-dependent manner, with half-maximum stimulation of tube formation at approximately 3.4% FBS. The length of tube formation decreased time-dependently at concentrations of 0.1 and 1.0 mol/L MeHg. Pretreatment of Matrigel with 1 mol/L MeHg before the cell seeding reduced the tube formation by HUVECs. These results suggest that the growth and tube formation by HUVECs is susceptible to MeHg cytotoxicity, and that MeHg could be injurious to endothelial cell function.Abbreviations MeHg methylmercury chloride - HUVECs human umbilical vein endothelial cells     

Rats that consume caffeine show decreased brain protein synthesis

The effect of caffeine on protein synthesis in brain and liver was studied. When caffeine was added to a post-mitochondrial supernatant from rat brain protein synthesis was inhibited, i.e. 1 mM caffeine about 20%. The effect on protein synthesis of two weeks administration of large doses of caffeine in the drinking fluid of rats was also measured. Caffeine decreased protein synthesis in rat brain by about 32% and 20% compared with ad libitum and pair-fed controls. Protein synthesis was calculated taking into account the levels of free leucine determined by HPLC: 0.10 mol/g brain of ad libitum; 0.11 for pair-fed and 0.07 for caffeine. The pattern of proteins synthesized was not significantly altered by caffeine as shown by gel-electrophoresis and fluorography. There was no effect on protein synthesis of liver. The possible significance of these results is briefly discussed.     

Characteristics of the ATP-ase activity of isolated neurons of rabbit

Summary Isolated and homogenised Deiters' neurons from the lateral vestibular nucleus of rabbit in a Krebs-Ringer solution containing no added Mg⁺⁺, 1.3 moles/ ml and 5 moles/ml Mg⁺⁺, broke down ATP at the maximal rate of 0.29+-0.20, 2.40+–0.20, and 5.95+–0.63 moles/cell/hr. In 1.3 mM Mg⁺⁺ solution the single cell homogenates took up phosphate at the mean rate of 2.6+–0.2 moles/cell/hr. If the rabbits were injected 1 hour before with 20 mg/kg body weight of 2-amino-1-propene-1,1,3, tricarbonitrile (triap), the breakdown of ATP in these latter media was 0.82+–0.44, 2,5+–0.60, and 6.7+– 1.1 moles/cell/hr, respectively, and the quantity of inorganic liberated did not decrease.     

Calpain-PKC Inter-Relations in Mouse Hippocampus: A Biochemical Approach

In previous studies, we isolated and identified a -calpain/PKC complex from rabbit skeletal muscle. Here, we have used specific purification procedures in order to study the interactions between -calpain and PKC in mouse hippocampus, a brain structure implicated in memory processes. We observed that -calpain and conventional PKCs (, II and ) are co-eluted after anion exchange chromatography. In contrast to our previous results obtained on skeletal muscle, -calpain and PKC isoenzymes were dissociated after gel filtration chromatography. Furthermore, -calpain induced the proteolytic conversion of PKC, II, and into PKM, II, and with a preferential hydrolysis of PKC, a specific isoenzyme of the nervous system. Although the -calpain/PKC interactions in the hippocampus are quite different from skeletal muscle, our results however, point out the functional importance of these inter-relations. Moreover, as PKC has been involved in the biochemical events underlying learning and memory, the preferential relationship between -calpain and PKC promotes the importance of the role that -calpain could play in the cellular mechanisms of memory formation.     

Plasma α- and γ-tocopherol have different pattern during normal human pregnancy

Plasma - and -tocopherol were monitored in pregnant women throughout healthy gestational periods and after delivery and were compared with that of non pregnant women. The mean plasma -tocopherol and -tocopherol concentrations in non pregnant Saudi women (15.2 ± 1.3 and 1.8 ± 0.2 ol/l respectively) were found within normal range. The maternal plasma -tocopherol level steadily increased reaching maximum level (19.1 ± 1.6 mol/l) at late gestation and then gradually decreased after delivery. On the contrary, the optimum level of -tocopherol (2.1 ± 0.2 mol/l) was at mid gestation, followed by a progressive decrease until one month after delivery (1.5 ± 0.1 ol/l). This study shows that the maternal plasma - and -tocopherol have different profiles that may be attributed to their different responses to the changes in maternal lipids during pregnancy.     

Thermal Stability of Glucose Oxidase from Penicillium adametzii

The thermal stability of glucose oxidase was studied at temperatures between 50 and 70°C by kinetic and spectroscopic (circular dichroism) methods. The stability of glucose oxidase was shown to depend on the medium pH, protein concentration, and the presence of protectors in the solution. At low protein concentrations (<15 g/ml) and pH > 5.5, the rate constants k _in, s^–1, for thermal inactivation of glucose oxidase were high. Circular dichroic spectra suggested an essential role of structures in stabilizing the protein globule. At a concentration of 15 g protein/ml, the activation energy E _Aof thermal inactivation of glucose oxidase in aqueous solution was estimated at 79.1 kcal/mol. Other thermodynamic activation parameters estimated at 60°C had the following values: H= 78.4 kcal/mol, G= 25.5 kcal/mol, and S= 161.9 entropy units. The thermal inactivation of glucose oxidase was inhibited by KCl, polyethylene glycols, and polyols. Among polyols, the best was sorbitol, which stabilized glucose oxidase without affecting its activity. Ethanol, phenol, and citrate exerted destabilizing effects.     

Regional and subcellular distribution of taurine-synthesizing enzymes in the rat central nervous system

The distribution of cysteine oxidase (CO) and cysteine sulfinate decarboxylase (CSD) was examined in 12 regions of the rat central nervous system (CNS). The distribution of CO activity, expressed as mol of cysteine sulfinate formed per h per g, was the following: hypothalamus, superior and inferior colliculi, 94–99 mol/h/g; olfactory bulbs, cerebral cortex, striatum, and hippocampus, 44–51 mol/h/g; cerebellum, 71 mol/h/g; pons-medula and spinal cord, 94 and 60 mol/h/g, respectively. The distribution of CSD activity expressed as mol of cysteine sulfinate decarboxylated per h per g was the following: hypothalamus and colliculi, 14–21 mol/h/g; olfactory bulbs, cerebral cortex, striatum, hippocampus, and cerebellum, 8–13 mol/h/g; pons-medulla, 7.3; and spinal cord, 3.6 mol/h/g. No CSD activity was detected in sciatic nerve. The subcellular distribution of CO and CSD activities was studied in hypothalamus, colliculi, and cerebral cortex. CO activity was localized in synaptosomes, mitochondria, and microsomes. CSD was primarily confined to the crude mitochondrial fraction and after subfraction, recovered mainly in the synaptosomal fraction.     

Regeneration of simon poplar (Populus simonii) from protoplast culture

Simon poplar (Populus simonii) protoplasts were isolated from suspension cells, with protoplast yield of 3.8×10⁷ g^–1 F. W. They were cultured in a K8P liquid medium containing 13.57M 2,4-D, 1.07M NAA and 0.93 M KT. Protoplast culture was influenced by the plating density, osmotic pressure, and the sources and amounts of nitrogen and carbon in the culture medium. Multiple shoots were produced from protoplast-derived callus after culture on MS medium containing 4.44 M BA, 2.32M KT, 2.28 M ZT, and 0.54M NAA. Shoots 2–3 cm in height were isolated from the calli and rooted on 1/2 MS medium. After transplantation into pots, the regenerated plants grew vigorously in greenhouse.Abbreviations BA N⁶-benzyladenine - NAA 1-naphthalene acetic acid - 2,4-D 2,4-dichlorophenoxy acetic acid - KT Kinetin - ZT Zeatin - 2ip 2-isopentenyl-adenine - FDA fluorescein diacetate - MES 2-(N-morpholino) ethane sulfonic acid - MS Murashige and Skoog basal medium (1962) - K8P Kao basal medium (1977) - CPW Cell and Protoplast Wash solution (Power and Davey 1980)     

In vitro somatic embryogenesis and plant regeneration in Acacia arabica

In vitro somatic embryogenesis and subsequent plant regeneration was achieved in callus cultures derived from immature zygotic embryos of Acacia arabica on semi-solid Murashige and Skoog (MS) basal salts and vitamins supplemented with 8.88 MBA, 6.78 M2,4-D and 30 g l^–1 (w/v) sucrose. Somatic embryos proliferated rapidly by secondary somatic embryogenesis after transfer to MS medium supplemented with 6.66 M BA, 6.78 M 2,4-D. The maximum number of somatic embryos per callus was 72.6 after 8 weeks of culture on medium containing 6.66 M BA and 6.78 M 2,4-D. The isolated somatic embryos germinated on half-strength basal MS salts and vitamins supplemented with 0.04 M BA, 0.94 M ABA and 2% (w/v) sucrose. The embryo-derived plantlets were acclimatized in the greenhouse and subsequently showed normal growth.     

The kinetics of photoinhibition and its recovery in the red alga Porphyridium cruentum

When Porphyridium cruentum cells were illuminated with high fluence rate between 1900 and 4800 mol photons m^-2s^-1, a decrease in the photosynthetic activity of the cells was observed. Within the time frame of 20 min, and under the fluence rates studied, the sum of photons to be absorbed by cells (mg of chlorophyll (Chl), sufficient to initiate photoinhibition was calculated to be 9235.8 mol. The minimal specific light absorption rate to initiate photoinhibition in P. cruentum ranges between 2.29 and 4.26 mol photons s^-1 mg^-1 chl.a. There was a linear relationship between the specific rate of photoinhibition and the specific light absorption rate. A photon number of 2.56×10⁴ mol mg^-1 chl.a photoinhibited photosynthesis instantaneously. At 15°C, no photoinhibitory effect was observed at 2300 mol photons m^-2 s^-1 even after 45 min of illumination. At the other extreme of 35°C, 84% inhibition of photosynthetic activity was observed within 10 min of exposure to 2300 mol photons m^-2 s^-1. Between 20 and 30°C, the photoinhibitory effect was comparable. Photoinhibited P. cruentum cells recovered readily when transferred to low light (90 mol photons m^-2 s^-1) and darkness, and the specific rate of recovery was independent of the light intensity to which the cells were exposed, during the photoinhibitory treatment.Abbreviations Chlorophyll QL, specific light absorption rate Publication No. 28 of the Microalgal Biotechnology Laboratory     

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