Defective remethylation of homocysteine is related to decreased synthesis of coenzymes B2 in thyroidectomized rats

Summary. We investigated the influence of hypothyroidism on homocysteine metabolism in rats, focusing on a hypothetical deficient synthesis of FAD by riboflavin kinases. Animals were allocated in control group (n=7), thyroidectomized rats (n=6), rats with diet deficient in vitamin B2, B9, B12, choline and methionine (n=7), thyroidectomized rats with deficient diet (n=9). Homocysteine was decreased in operated rats (2.6±1.01 vs. 4.05±1.0mol/L, P=0.02) and increased in deficient diet rats (29.56±4.52 vs. 4.05±1.0mol/L, P=0.001), when compared to control group. Erythrocyte-Glutathione-Reductase-Activation-Coefficient (index of FAD deficiency) was increased in thyroidectomized or deficient diet rats (P=0.004 for both). Methylenetetrahydrofolate-reductase and methionine-synthase activities were decreased in thyroidectomized rats but not in those subjected to deficient diet. Cystathionine--synthase was increased only in operated rats. Taken together, these results showed a defective re-methylation in surgical hypothyroidism, which was due in part to a defective synthesis of vitamin B2 coenzymes. This defective pathway was overcompensated by the increased Cystathionine--synthase activity.     

Theoretical studies of biliverdin: energetics of the reduction pathways to bilirubin

Geometries and energies of formation of bilirubin formed by reduction of biliverdin via three meso carbon sites, the , and positions, have been calculated using semiempirical methods. It has been shown that -bilirubin with a ridge-tile conformation forms six intramolecular hydrogen bonds and is the most stable of the three above mentioned positions by at least 22 kcal mol^–1. Reduction pathways for -, - and -bilirubin formations from biliverdin are studied in detail. The roles of loss of conjugation and hydrogen bond formations in stability of different conformers have been discussed. -Bilirubin was fully optimized by using ab initio methods. Fine refinements of calculated results show excellent agreement with experimental results. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00894-002-0078-9.Electronic Supplementary Material available.     

CK2α - protein phosphatase 2A molecular complex: Possible interaction with the MAP kinase pathway

Despite its wide range of known substrates, the signaling function of protein kinase CK2 is still enigmatic. Mounting evidence suggests that CK2, the catalytic subunit of holoenzymic CK2, may exist free of its usual regulatory partner CK2, raising the possibility that free CK2 has regulation and function distinct from those of the holoenzyme. We previously reported that CK2 could bind to the core dimer of protein phosphatase 2A, and indirectly cause down-regulation of the PP2A substrate MEK1, possibly via activation of PP2A and/or targeting of PP2A to some element of the Ras/Raf/MEK pathway. Here, these results are confirmed and extended. By using transfection experiments and immune kinase assays, we show that endogenous PP2Ac and CK2 are the only major substrates associating with epitope-tagged CK2, and that expression of activated Raf results in disruption of the CK2- PP2A association. Such disruption might be a necessary step for maximal activation of the MAP kinase pathway by Raf. In keeping with this idea, overexpression of CK2 dose-dependently inhibits the mitogen-induced activation of cotransfected, epitope-tagged MAP kinase. We suggest that the CK2 free form of CK2 is both a target and a regulator of Raf/MAPK signaling.     

The HPLC resolution of N-2,4-dinitrophenylated amino acids and peptides stereoisomers on naphthylethylcarbamate-β-cyclodextrin bonded phase using the acetonitrile-based mobile phase: evidence for the chiral recognition pattern

Summary. A facile method of enantioresolving a variety of -amino acids and peptides on naphthylethylcarbamate--cyclodextrin bonded phases (i.e., SN- and RN--CDs) under the elution of acetonitrile-based mobile phase makes use of 2,4-dinitrofluorobenzene (DNFB) as the tagging reagent, which undergoes nucleophilic substitution by the free amino group in alkaline medium to give a N-2,4-dinitrophenyl (DNP) derivative. The resolution is better obtained on RN--CD phase and fails to reproduce on the intact -cyclodextrin bonded phase under the same chromatographic conditions, which strongly suggests that the observed resolution should be due to the interaction of analyte with naphthylethylcarbamate moiety, not with the residual secondary hydroxyl groups on the -cyclodextrin.     

Yeast ribosomal proteins

Summary Homology maps between bacteriophages 81, 80 and were constructed on the basis of electron microscope observation of DNA heteroduplexes. In 81/80 heteroduplex, the left half and the right terminal region of 13% the total molecular length were highly homologous, while the remaining region covering the early gene cluster was entirely nonhomologous. In 81/ heteroduplex, high-degree homologies were detected at the left 14% terminal region covering the head gene cluster, the central 3.8% region covering the att-int-xis region and the 1.3% Q homology region. Low-degree homologies of shorter length were scattered at the tail gene cluster, b2 region, cIII region, PQ region and SR region. Comparing our results with the homology maps of other lambdoid phages reported by Simon et al. (1971) and Fiandt et al. (1971), a phylogenic relation of 81 to other lambdoid phages and the role of recombination in the course of divergence of lambdoid phages are discussed.     

Recombinant interferon γ up-regulates in vivo and down-regulates in vitro monocyte CD14 antigen expression in cancer patients

Summary The expression of the monocyte membrane glycoprotein CD14 was measured and related to the serum interferon (IFN) concentration in thirteen patients with disseminated cancer during treatment with human recombinant interferon (rIFN). The drug was administered by continuous subcutaneous infusion using an escalating dose schedule, starting at 50 µg/day or 100 µg/day and increasing weekly up to 600 µg/day, if tolerated. Treatment was continued at a mean maximal tolerated dose of 200 µg/day for a median duration of 43 days. Serum IFN concentration and monocyte CD14 antigen expression (immunofluorescence with the monoclonal antibody LeuM3 and fluorescence-activated cell sorting analysis) were determined weekly. The serum IFN concentration was positively correlated with the rIFN dose (P <0.05). Therapy induced a dose-dependant enhancement of CD14 antigen expression. The increase in mean CD14 fluorescence intensity was on average 60% after 3 weeks of treatment at a mean dose of 220 µg rIFN/day and was reversed after withdrawal of therapy. Patients with a rapidly rising serum IFN concentration (starting dose 100 µg/day) showed a smaller increment in CD14 fluorescence intensity than those with slowly rising serum IFN levels (starting dose 50 µg/day). Since rIFN is known to down-regulate CD14 antigen expression in vitro, monocytes from patients off therapy and from healthy volunteers were cultured with this cytokine. A similar decrease of CD14 fluorescence was observed in both groups. In patients several factors, such as IFN concentration, duration of drug effect and type of serum, were evaluated and could not explain the discrepant in vivo and in vitro findings. In conclusion, the monocyte marker CD14 was found to be differentially regulated by rIFN in vivo and in vitro. In vivo, secondary mediators, induced by rIFN and acting on a constantly renewed cell population, may contribute to the enhanced CD14 expression.     

Improved production of ginseng polysaccharide by adding conditioned medium to Panax notoginseng cell cultures

By adding 50% (v/v) filtered culture broth to fresh MS medium, the specific growth rate of Panax notoginseng was increased from 0.046 d–1 to 0.068 d–1, and the polysaccharide production and productivity reached 1.21 g l–1 and 61 mg/(ld), respectively, which were 1.3- and 2.3-fold of the control. Further supplementation of the conditioned medium with sucrose, ammonium, nitrate and phosphate gave a cell density of 13.7 g l–1 and a specific growth rate of 0.086 d–1. Polysaccharide production was 1.65 g l–1 and the productivity was 78 mg/(ld).     

CO2 gas exchange of benthic microalgae during exposure to air: a technique for the rapid assessment of primary production

A method of measuring CO₂gas exchange (caused, for example, by microalgal photosynthesis on emersed tidal mudflats) using open flow IR gas analyzers is described. The analyzers are integrated in a conventional portable photosynthesis system (LI-6400, LI-COR, Nebraska, USA), which allows manipulation and automatic recording of environmental parameters at the field site. Special bottomless measuring chambers are placed directly on the surface sediment. Measurements are performed under natural light conditions and ambient CO₂concentrations, as well as under different CO₂concentrations in air, and various PAR radiation levels produced by a LED light source built into one of the measurement chambers. First results from tidal channel banks in a north Brazilian mangrove system at Bragança (Pará, Brazil) under controlled conditions show a marked response of CO₂assimilation to CO₂concentration and to irradiance. Photosynthesis at 100molmol^–1CO₂in air in one sample of a well-developed algal mat was saturated at 309mol photons m^–2s^–1, but increased with increasing ambient CO₂concentrations (350 and 1000mol mol^–1CO₂) in the measuring chamber. Net CO₂assimilation was 0.8mol CO₂m^–2s^–1at 100mol mol^–1CO₂, 5.9mol CO₂m^–2s^–1at 350mol mol^–1CO₂and 9.8mol CO₂m^–2s^–1at 1000mol mol^–1CO₂. Compensation irradiance decreased and apparent photon yield increased with ambient CO₂concentration. Measurements under natural conditions resulted in a quick response of CO₂exchange rates when light conditions changed. We recommend the measuring system for rapid estimations of benthic primary production and as a valuable field research tool in connection with certain ecophysiological aspects under changing environmental conditions.     

Role of mitochondria in ethanol tolerance of Saccharomyces cerevisiae

The presence of active mitochondria and oxidative metabolism is shown to be essential to maintain low inhibition levels by ethanol of the growth rate (), fermentation rate (v) or respiration rate () of Saccharomyces cerevisiae wild type strain S288C. Cells which have respiratory metabolism show K _i (ethanol inhibition constant) values for , v and , higher (K _i>1 M) than those of petite mutants or grande strains grown in anaerobiosis (K _i=0.7 M). In addition, the relationship between or v and ethanol concentration is linear in cells with respiratory metabolism and exponential in cells lacking respiration. When functional mitochondria are transferred to petite mutants, the resulting strain shows K _i values similar to those of the grande strain and the inhibition of and v by increasing ethanol concentrations becomes linear.     

Taurine protected myocardial mitochondria injury induced by hyperhomocysteinemia in rats

Summary. Taurine can protect against cardiovascular diseases, whereas elevated levels of plasma homocysteine are associated with atherosclerotic and thromboembolic cardiovascular diseases. To illustrate the effects of taurine on hyperhomocysteinemia, we observed the myocardial mitochondria dysfunction in the rats with hyperhomocysteinemia induced by diet methionine loading, and the therapeutic effect of taurine. A methionine diet increased plasma homocysteine concentration (133.51±27.91mol/L vs 12.31±2.58mol/L in control, P<0.01), stimulated the production of reactive oxygen species (ROS) in the myocardial mitochondria, and inhibited the activities of mitochondrial Mn-superoxide dismutase and catalase. The ⁴⁵Ca uptake and Ca²⁺-ATPase activity in the myocardial mitochondria were significantly lowered in rats with hyperhomocysteinemia. Taurine supplements effectively attenuated the hyperhomocysteinemia-induced ROS production and inhibition of Mn-superoxide dismutase and catalase activities in the myocardial mitochondria, and increased its ⁴⁵Ca uptake and Ca²⁺-ATPase activity. Thus, taurine antagonizes the oxidative stress injury in the myocardial mitochondria induced by the hyperhomocysteinemia.     

Immunocytochemical study by two photon fluorescence microscopy of the distribution of GABA<Subscript>A</Subscript> receptor subunits in rat cerebellar granule cells in culture

Summary. An immunocytochemical investigation of the expression of ₁, ₆, _2/3, ₂ and subunits was performed on rat cerebellum granule cells in culture by the two photon microscopy technique.The first four subunits appear to be expressed abundantly in these cells, whereas the one seems to be expressed at a lower level. Another major difference in the distribution of these subunits is that whereas ₆, _2/3 and ₂ appear only on plasma membranes ₁ and are present mainly in the cell bodies cytoplasm. Still another difference was found in that the presence of ₂ on neurites is polarized, preferentially labelling neurites with the appearance of dendrites. The subunits ₆ and _2/3 appear to label all types of neurites, with _2/3 being by far the most heavily expressed subunit type. A final distinct characteristic is that ₆ and, even more, ₂ appear to accumulate in the cytoplasmic domains immediately below the cone of emergence of neurites. This suggests a conspicuous transport of such subunits from the site of synthesis in the cell body to the site of final expression in the neurites (dendrites and axon terminals).     

The dynamic effects of inputs to spinal motoneurones of different type upon the outputs of γ-motoneurones mediated via recurrent inhibition

A previous dynamic model of the spinal motoneurone-Renshaw cell system has been extended by integrating -motoneurones (-MNs), which are also supposed to represent Ia inhibitory interneurones mediating reciprocal inhibition. For the recurrent inhibition of -MNs, two cases are considered: -MNs inhibiting themselves via Renshaw cells (RCs), and -MNs not subjected to self-inhibition. Two input systems are taken into account: monosynaptic Ia input distributed inhomogeneously to the three types of -MNs (S, FR, and FF), and spinally descending input from the lateral vestibular nucleus distributed inhomogeneously to the three -MN types and to -MNs. Dynamic input-output relations have been calculated in form of Bode or polar plots. The main results are: Input signals (Ia and VST) to -MNs are transmitted via RCs to -MNs with high-pass characteristics (lower cut-off around 1 Hz). The relatively high gains at high frequencies are attenuated more or less strongly by recurrent self-inhibition of -MNs depending on the overall strength of recurrent inhibition. The phase lags of -MNs with respect to the input are not frequency-independent, but vary between about-90° and-180° (at times up to-200°). To preserve in-phase activation of -and -MNs, certain criteria have to be met which are discussed in terms of additional input systems to -MNs and RCs.     

Adoptions expérimentales de larves entre des fourmis de genres différents (II):Myrmica laevinodis Nylander etAnergates atratulus Schenck

Résumé Nous avons fait élever des larves d'Anergates atratulus par des ouvrières deMyrmica laevinodis à 22°C. Pour y parvenir, il n'est pas utile de faire hivernerensemble les larves d'Anergates et les ouvrières deMyrmica. La présence de larves autochtones n'empêche pas lesMyrmica d'élever des larves d'Anergates. Dans toutes les expériences lesMyrmica ont été soumises au fridavant de recevoir des larves d'Anergates. Aucune reine deMyrmica n'a été utilisée dans ces expériences.Sur les 64 larves d'Anergates que nous avons utilisées, 38 se sont transformées en imagos. C'est au début de l'adoption et au moment des métamorphoses que périrent la plupart des 26Anergates perdus. Les femelles vécurent en général 2 ou 3 jours et cherchèrent très tôt à quitter le nid natal. Les mâles vécurent 2 à 3 semaines.

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Summary Larvae ofAnergates atratulus were experimentally reared by workers ofMyrmica laevinodis, at 22°C. An overwintering of both larvae ofAnergates and workers ofMyrmica is not necessary for the success of that experiment. The presence of larvae ofMyrmica does not keep theMyrmica from rearing larvae ofAnergates. The workers ofMyrmica have been cooled, in all the experiments, before receiving larvae ofAnergates. No queen ofMyrmica have been used in that experiments.38 of the 64 larvae ofAnergates used became imagos. Most of the 26 lostAnergates died at the beginning of the adoption and during the metamorphosis. The females lived generally 2 or 3 days and tried, very early, to leave their native nest. The males lived 2 or 3 weeks.

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Anergates atratulus Myrmica laevinodis, 22 . bmecme Anergates Myrmica. Myrmica Anergates. Myrmica Anergates. Myrmica . 64 Anergates , 38 . 26 Anergates 2 3 . 2 3 .

     

Synthesis of Gal-β-(1→4)-GlcNAc-β-(1→6)-[Gal-β- (1→3)]-GalNAc-α-OBn oligosaccharides bearing O-methyl or O-sulfo groups at C-3 of the Gal residue: specific acceptors for Gal: 3-O-sulfotransferases

Our recent studies have revealed the existence of two distinct Gal: 3-O-sulfotransferases capable of acting on the C-3 position of galactose in a Core 2 branched structure, e.g., Gal14GlcNAc16(Gal13)GalNac1OBenzyl as acceptor to give 3-O-sulfoGal14GlcNAc13(Gal13)GalNAc1OB 20 and Gal14GlcNAc16(3-O-sulfoGal13)GalNAc1OB 23. We herein report the synthesis of these two compounds and also that of other modified analogs that are highly specific acceptors for the two sulfotransferases. Appropriately protected 1-thio-glycosides 7, 8, and 10 were employed as glycosyl donors for the synthesis of our target compounds.     

Construction of stable lactose-utilizing Xanthomonas campestris by chromosomal integration of cloned lac genes using filamentous phage ϕLf DNA

Summary Previously, we constructed a lactose-utilizing strain of Xanthomonas campestris, Xc17 (pKMLT), by cloning lacZY genes with the RK2-derived vector pLAFR1. In this study, the narrow-host-range, -galactosidase expression plasmid pKM was fused with an integration vector pS19 to form pSF14. Following insertion into Xc17, pSF14 was integrated into the host chromosome. The integration function was provided by the 0.85-kb EcoRI-PstI fragment from the filamentous phage Lf. The integration caused no adverse effect to the cells and was stable for at least 66 generations without selection. The engineered strain, Xc17::pSF14, was able to grow as well and produce as much xanthan gum in lactose medium as the wild-type cells did in glucose medium, and the Xc17(pKMLT) in lactose medium. Therefore, Xc17::pSF14 is potentially useful for xanthan production by direct use of whey lactose as the fermentation substrate. This study has advanced one more step our efforts to contruct lactose-utilizing X. campestris and confirmed the feasibility of using pS19 as an integration vector.     

Speculations on the origin of the genetic code

The most primitive code is assumed to be a GC code: GG coding for glycine, CC coding for proline, GC coding for alanine, CG coding for arginine. The genetic code is assumed to have originated with the coupling of glycine to its anticodon CC mediated by a copper-montmorillonite. The polymerization of polyproline followed when it was coupled to its anticodon GG. In this case the aminoacyl-tRNA synthetase was a copper-montmorillonite. The first membrane is considered to be a sheet formed from polyglycine. As the code grew more complicated, the alternative hydrophobic-hydrophilic polypeptide (alanine-arginine) was coded for by the alternating CG copolymer. This alternating polypeptide (ala-arg) began to function as both a primitive membrane and as an aminoacyl-tRNA synthetase. The evolution of protein structure is tightly coupled to the evolution of the membrane. The a helix was evolved as lipids became part of the structure of biological membranes. The membrane finally became the fluid mosaic structure that is now universal.Based on a presentation made at a workshop-Aminoacyl-tRNA Synthetases and the Evolution of the Genetic Code-held at Berkeley, CA, July 17–20, 1994     

Greek classicism in living structure? Some deductive pathways in animal morphology

Classical temples in ancient Greece show two deterministic illusionistic principles of architecture, which govern their functional design: geometric proportionalism and a set of illusion-strengthening rules in the proportionalism's stochastic margin. Animal morphology, in its mechanistic-deductive revival, applies just one architectural principle, which is not always satisfactory. Whether a Greek Classical situation occurs in the architecture of living structure is to be investigated by extreme testing with deductive methods.Three deductive methods for explanation of living structure in animal morphology are proposed: the parts, the compromise, and the transformation deduction. The methods are based upon the systems concept for an organism, the flow chart for a functionalistic picture, and the network chart for a structuralistic picture, whereas the optimal design serves as the architectural principle for living structure. These methods show clearly the high explanatory power of deductive methods in morphology, but they also make one open end most explicit: neutral issues do exist.Full explanation of living structure asks for three entries: functional design within architectural and transformational constraints. The transformational constraint brings necessarily in a stochastic component: an at random variation being a sort of free management space. This variation must be a variation from the deterministic principle of the optimal design, since any transformation requires space for plasticity in structure and action, and flexibility in role fulfilling. Nevertheless, finally the question comes up whether for animal structure a similar situation exists as in Greek Classical temples. This means that the at random variation, that is found when the optimal design is used to explain structure, comprises apart from a stochastic part also real deviations being yet another deterministic part. This deterministic part could be a set of rules that governs actualization in the free management space.     

The relationships between the structure of paddy levees and the plant species diversity in cultural landscapes on the west side of Lake Biwa,Shiga, Japan

Paddy levees form networks of narrow linear habitats and play various roles in cultural landscapes. Traditional landscapes on the west side of Lake Biwa consist of paddy field terraces and both stone and soil levees that have been maintained by paddy field management using local resources. Paddy levees in this study site are principally classified into five different types. Our study points out how differences in paddy levee structure as well as in management practices influence the plant species. Seventeen paddy levee transects were split into four habitat types based on their species components by TWINSPAN. Spatial characteristics and physical structures of paddy levees depended on natural conditions and human activities. The species–area curves of each levee type showed a clear distinction: the soil, stone and abandoned curves were steep, while the concrete and consolidated ones were gentle. The vegetation on consolidated levees was utterly different from the vegetation on traditional levee types from the aspect of species richness and species components. Soil type levees contained various woody plant species and included more diverse and indigenous plant species than abandoned type levees.