Larval length as evidence for maternal effects correlated with thepn/K-pn interaction inDrosophila melanogaster

Summary In order to confirm the time and the pleiotropic effects of thepn/K-pn interaction the lengths of second instar larvae were measured. Length-frequency distributions of samples of larvae derived from the crosspn/pn; + +/ + + × +/-; ca K-pn/ ca K-pn are bimodal; the one partial collective covers small lethal male larvae, the other partial collective represents the large viable female larvae (Fig. 1a). The expectation that the progeny of the backcrossespn/ +; ca K-pn/ + + × pn/-; + +/ + + andpn/ +; ca K-pn/ + + × +/-; ca K-pn/ ca K-pn also exhibits a bimodal distribution of larval lengths is not fulfilled: during the whole second larval instar the larval lengths are normally distributed (Figs. I c, d). This results indicates that a maternal effect is involved in thepn/K-pn interaction.     

Close genetic relationship between Nitrobacter hamburgensis nitrite oxidoreductase and Escherichia coli nitrate reductases

The nitrite oxidoreductase (NOR) from the facultative nitrite-oxidizing bacterium Nitrobacter hamburgensis X14 was investigated genetically. In order to develop a probe for the gene norB, the N-terminal amino acid sequence of the NOR -subunit (NorB) was determined. Based on that amino acid sequence, an oligo-nucleotide was derived that was used for the identification and cloning of gene norB. Sequence analysis of DNA fragments revealed three adjacent open reading frames in the order norA, norX, norB. The DNA sequences of norX and norB represented complete genes while the open reading frame of norA was truncated by the cloning site. The deduced amino acid sequence of protein NorB contained four cysteine clusters with striking homology to those of iron-sulfur centers of bacterial ferredoxins. NorB shares significant sequence similarity to the -subunits (NarH, NarY) of the two dissimilatory nitrate reductases (NRA, NRZ) of Escherichia coli. Additionally, the derived amino acid sequence of the truncated open reading frame of norA showed striking resemblance to the -subunits (NarG, NarZ) of the E. coli nitrate reductases.     

Ringworm in rabbit due to Trichophyton quinckeanum

Summary Trichophyton quinckeanum was isolated from a spontaneous infection in rabbit. The hairs were also invaded by the fungus, exibiting a yellowish fluorescence in Wood's light. White mice inoculation of the isolate produced typical scutula with hair penetration fluorescing in green colour. The type of animal hair invasion is also discussed. The morphologic features ofTr. quinckeanum, together with its ability of producing scutula while inoculating the white mice, must be emphasized, when proving its separate identity.     

Mutational specificity of ethyl methanesulfonate in excision-repair-proficient and -deficient strains of Drosophila melanogaster

Summary The vermilion gene was used as a target to determine the mutational specificity of ethyl methanesulfonate (EMS) in germ cells of Drosophila melanogaster. To study the impact of DNA repair on the type of mutations induced, both excision-repair-proficient (exr ⁺) and excision-repair-deficient (exr ^–) strains were used for the isolation of mutant flies. In all, 28 mutants from the exr ⁺ strain and 24 from the exr ^– strain, were characterized by sequence analysis. In two mutants obtained from the exr ⁺ strain, small deletions were observed. All other mutations were caused by single base-pair changes. In two mutants double base-pair substitutions had occurred. Of the mutations induced in the exr ⁺ strain, 22 (76%) were GCAT transitions, 3 (10%) ATTA transversions, 2 (6%) GCTA transversions and 2 (6%) were deletions. As in other systems, the mutation spectrum of EMS in Drosophila is dominated by GCAT transitions. Of the mutations in an exr ^– background, 12 (48%) were GCAT transitions, 7 (28%) ATTA transversions, 5 (20%) GCTA transversions and 1 (4%) was a ATGC transition. The significant increase in the contribution of transversion mutations obtained in the absence of an active maternal excision-repair mechanism, clearly indicates efficient repair of N-alkyl adducts (7-ethyl guanine and 3-ethyl adenine) by the excision-repair system in Drosophila germ cells.     

Fertility of somatic hybrids from protoplast fusions of Solanum brevidens and S. tuberosum

Summary Two sets of somatic hybrids between Solanum brevidens (2x) and S. tuberosum (2x and 4x) were evaluated for male fertility, meiotic regularity and female fertility. The somatic hybrids were tetraploids from 2x + 2x fusions and hexaploids from 2x + 4x fusions. Pollen stainability ranged from 0 to 83% in tetraploids and from 0 to 23% in hexaploids. The tetraploids had more regular meiosis, lower levels of micropollen and fewer unassociated chromosomes than hexaploids. However, except for a low level of selfing, the pollen of both sets of hybrids was ineffective in pollinations. The tetraploids, as females, crossed poorly with 2x and 4x tester species and selfed only at low levels. The hexaploid fusion hybrids also crossed poorly with the 2x tester species and selfed only to a limited degree; however, they crossed well with 4x testers. Seed set in crosses with S. tuberosum Group Andigena, and S. tuberosum Group Tuberosum cultivars Kathadin and Norland averaged 16.7, 15.6 and 28.6 seeds per fruit, respectively. Progeny from these crosses had 5x or nearly 5x ploidy levels. The results indicate that reasonable levels of female fertility can be obtained in somatic fusion hybrids of S. brevidens and S. tuberosum.Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable     

Stage and organ specificity of the degree of variegation of the 6-phosphogluconate dehydrogenase gene in Drosophila melanogaster

Summary The effects of chromosomal rearrangements pn2, pn3, TE100 and TE101 on variegation of the gene Pgd, which controls the synthesis of 6-phosphogluconate dehydrogenase (PGD), were studied in Drosophila melanogaster. The electrophoretic patterns of PGD activity were first examined at different developmental stages. The degree of variegation of Pgd caused by pn2 and pn3 was higher in adult flies (the calculated percentage of cells with inactive Pgd was 70%–80%) as compared with larvae (about 50%). This difference can be explained by the tissue-specific mosaicism of Pgd expression; variegation was high in the neural ganglia, imaginal discs, and posterior gut but relatively low in the salivary glands, fat bodies and Malpighian tubes. In the case of TE100, neither tissue specificity, nor marked differences in the degree of variegation between larvae and adults were found. None of the rearrangements examined had an effect on the expression of Pgd in the ovary cells, but repression was seen in some cells of the male gonads. The data obtained suggest that the timing of clonal initiation is influenced by the rearrangements studied. The possible mechanisms preventing changes in the expression of the Pgd gene in the nurse cells caused by these rearrangements are discussed.     

Light and dark metabolism ofl- andd-amino acids in 5 strains ofChlorella vulgaris and 4 strains of the genusAnkistrodesmus

In the light, 2 out of the 4 newly testedChlorella vulgaris strains were found to use about as many amino acids as a source of nitrogen as the previously investigated strain Delft; the other 2C. vulgaris strains and 3 of theAnkistrodesmus strains used only a few. The 4thAnkistrodesmus strain used none.On the average,l-amino acids supported better growth thand-amino acids, butd-serine was preferred tol-serine by 3Ankistrodesmus strains.In the dark, growth was only obtained withC. vulgaris strain Delft, and only on a few of thel-amino acids,l-leucine in particular.The author is indebted to the Direction of the Academic Hospital Dijkzigt, Rotterdam and to Prof. Dr. H. Esseveld, Head of the Central Bacteriological Laboratory, Rotterdam, for providing facilities for the performance of this study.He thanks Mrs. Dr. H. J. Leijnse-Ybema for her help in making the chromatograms, and Mr. J. B. Lenstra, pharmacist, for advice in matters of organic chemistry.     

Molecular species of membrane phospholipids containing arachidonic acid and linoleic acid contribute to the interindividual variability of red blood cell Na+-Li+ countertransport: In vivo and in vitro evidence

Summary Previous studies indicate a particular sensitivity of red blood cell Na⁺-Li⁺ countertransport activity to small variations in the fatty acid composition of membrane phospholipids. To assess whether the interindividual variability of Na⁺-Li⁺ countertransport is related to differences in the species pattern of erythrocyte phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in vivo, the molecular species composition of PC and PE as well as the kinetics of Na⁺-Li⁺ countertransport were analyzed in parallel in normo- and hyperlipidemic donors. Both in diacyl PC and in diacyl-PE the species 160/204 and 160/182 were, respectively, positively and negatively related to the apparent maximal velocity of Na⁺-Li⁺ countertransport. The sum of all species with 204 at sn₂ of diacyl-PE exhibited a strong positive (r = 0.82, 2p < 0.001), and those containing 182 a negative correlation (r = –0.63, 2p < 0.01) to the transport activity. Essentially similar connections were observed between these species and the apparent affinity of the transport system for intracellular Na⁺. To evaluate whether the associations between molecular species of membrane phospholipids and Na⁺-Li⁺ countertransport activity were indicative of a causal relationship, the species 160/204-PC and 160/182-PC were selectively introduced into the erythrocyte membrane by means of the PC-specific transfer protein. Replacement of 11% of native PC by 160/182-PC inhibited the transport rate by about 25%. Exchange of 6 and 9% of PC with 160/204-PC, in contrast, accelerated the transport rate by 30 and 60%, respectively. The accordance between the in vivo relations and the results of the in vitro modification strongly suggests that elevations and reductions in the arachidonic acid and linoleic acid content of membrane PC and PE contribute to the interindividual variability of red blood cell Na⁺-Li⁺ counter-transport activity and its acceleration in hyperlipidemias.The authors wish to thank Dr. W.O. Richter (II. Medizinische Klinik, Klinikum Großhadern, Universität München) for selection of the patients and Dr. T. Brosche (Universität ErlangenNürnberg) for gaschromatographic analyses. This study was supported in part by a grant of the Wilhelm-Sander-Stiftung to B.E.     

Arsenic‐induced NFκβ transactivation through Erks‐ and JNKs‐dependent pathways in mouse epidermal JB6 cells

Carnosine, a alanylLhistidine dipeptide with antioxidant properties is present at high concentrations in skeletal muscle tissue. In this study, we report on the antioxidant activity of carnosine on muscle lipid and protein stability from both in vitro and in vivo experiments. Carnosine inhibited lipid peroxidation and oxidative modification of protein in muscle tissue prepared from rat hind limb homogenates exposed to in vitro Fenton reactant (Fe²⁺, H₂O₂)generated free radicals. The minimum effective concentrations of carnosine for lipid and protein oxidation were 2.5 and 1 mM, respectively. Histidine and alanine, active components of carnosine, showed no individual effect towards inhibiting either lipid or protein oxidation. Skeletal muscle of rats fed a histidine supplemented diet for 13 days exhibited a marked increase in carnosine content with a concomitant reduction in muscle lipid peroxidation and protein carbonyl content in skeletal muscle caused by subjecting rats to a Fenitrilotriacetate administration treatment. This significant in vitro result confirms the in vivo antioxidant activity of carnosine for both lipid and protein constituents of muscle under physiological conditions.     

Six newSalmonella types,isolated in ghana (S. volta,S. agona,S. wa,S. techimani,S. mampong andS. tafo)

Summary Six newSalmonella types isolated in Ghana are described.S. volta, 11: 4: 1,z₁₃, z₂₈ was isolated from a swine;S.agona 4,12: fgs:—,S.wa, 16: b: 1,5S.technimani, 28: c: z₆ andS.tafo, 1, 4 12, 27: z₃₅: 1,7 were isolated from cattle;S.mampong, 13,22: z₃₅: 1,6, was isolated from a lizzard.     

Agrobacterium-mediated transformation of apple (Malus x domestica Borkh.): an assessment of factors affecting regeneration of transgenic plants

We have previously developed a protocol for efficient gene transfer and regeneration of transgenic calli following cocultivation of apple (cv. Jonagold) explants with Agrobacterium tumefaciens (De Bondt et al. 1994, Plant Cell Reports 13: 587–593). Now we report on the optimization of postcultivation conditions for efficient and reproducible regeneration of transgenic shoots from the apple cultivar Jonagold. Factors which were found to be essential for efficient shoot regeneration were the use of gelrite as a gelling agent and the use of the cytokinin-mimicing thidiazuron in the selective postcultivation medium. Improved transformation efficiencies were obtained by combining the hormones thidiazuron and zeatin and by using leaf explants from in vitro grown shoots not older than 4 weeks after multiplication. Attempts to use phosphinothricin acetyl transferase as a selectable marker were not successful. Using selection on kanamycin under optimal postcultivation conditions, about 2% of the leaf explants developed transgenic shoots or shoot clusters. The presence and expression of the transferred genes was verified by -glucuronidase assays and Southern analysis. The transformation procedure has also been succesfully applied to several other apple cultivars.Abbreviations BAP benzylaminopurine - CTAB hexadecyltrimethylammoniumbromide - Na₂EDTA ethylenediamine-tetra-acetate ferric-sodium salt - FeNaEDTA ethylenediamine-tetra-acetate ferric-sodium salt - GA₃ gibberellic acid 3 - GusA -glucuronidase - gusA -glucuronidase gene of Escherichia coli - IAA indole acetic acid - IBA indole butyric acid - 2iP N6-2-isopentenyl adenine - NAA naphthalene acetic acid - nptII neomycinphosphotransferase II gene - bar phosphinothricin acetyl transferase gene - PCR polymerase chain reaction - PPT phosphinothricin - STS silver thiosulphate - T-DNA transferred DNA - TDZ thidiazuron - X-Gluc 5-bromo-4-chloro-3-indolyl -D-glucuronide - Zea trans-Zeatin     

4-Isobutyl homologs of farnesyl bacteriochlorophyll c in carbon tetrachloride

Absorption (ABS) and circular dichroism (CD) spectra were recorded for 3 concentrations (2.3, 19 and ca. 75 M) of 4-isobutyl homologs. Monomer spectra were the same as those for 4-n-propyl-5-ethyl farnesyl bacteriochlorophyll c. Pure polymer spectra were obtained by subtracting the 2.3-M spectra appropriately scaled from the ca. 75-M spectra. The polymer showed an ABS peak at 742 nm and a CD trough at ca. 742 nm. These properties are in harmony with the aggregate model proposed by Smith KM, Kehrs LA and Fajer J (1983, J Am Chem Soc 105: 1387–1389). A log-logplot of absorbance at 742 nm vs. monomer concentration could be fitted by a straight line of slope 1.6.Abbreviations ABS absorbance - BChl bacteriochlorophyll - CD circular dichroism - iBM/EF 4-isobutyl-5-methyl/ethyl farnesyl - PEF 4-n-propyl-5-ethyl farnesyl     

A dynamic model of a two-synapse feedback loop in the vertebrate retina

The theoretical properties of synapses such as those in the retina which operate on graded potentials are developed using work on tetrodotoxin-treated synapses as a basis. A linearized model of a two-synapse negative feedback loop analogous to the bipolaramacrine feedback loop in the retina possesses a frequency response which developes an increasingly prominent resonance peak at higher input levels and under some circumstances shows instability. Psychophysical studies have shown that the visual system also exhibits this behaviour suggestive of progressive underdamping in a harmonic oscillator. Evidence in favor of the hypothesis that resonance originates in the loop is presented, the conclusions being that the loop functions to tune the retina to a range of temporal frequencies.Symbol Table V millivolts depolarisation relative to resting membrane potential - V _n , V _out pre-synaptic, post-synaptic depolarisation respectively - V _e , V _i reversal potential or e.m.f. of post-synaptic battery of excitatory, inhibitory synapses respectively - V _out (max) maximal post-synaptic depolarisation defined by Eq.(10c) - V ₀ input depolarisation for feedback loop - depolarisation potential normalised with respect to V _out(max) - I milliamperes of depolarising current - I _s post-synaptic membrane current - I _c cable current - I ₀ input depolarising current for feedback loop - I _max maximal physiological value for I ₀ =V _e ·G ₀ - i depolarising current normalised with respect to I_max - e reversal potential normalised with respect to V _e - r _i specific resistivity of internal medium - R _m membrane resistance - C _m membrane capacitance - cable space constant = R _m /2R _i - g ₀ characteristic cable conductance = 2/R _m ·R _i - G conductance of post-synaptic membrane - G _s maximal post-synaptic membrane conductance - g fraction of receptors occupied by transmitter = G/G _s - r the ratio G _s/G ₀ - membrane time constant = R _m·C_m - ₁ time constant of transmitter release in response to presynaptic depolarisation [Eq. (6)] - ₂ time constant of decay of g [Eq. (7a)] - _{2 2}·[1+k·exp(b·v _in)]^–1 - k equilibrium constant for transmitter-receptor interaction [Eq. (7a)] - b constant determining increase in rate of transmitter release with pre-synaptic depolarisation [Eq. (6)] - c concentration of transmitter in synaptic cleft normalised with respect to resting concentration - H _jk (s) linearised transfer function for synaptic transmission from neurone j to neurone k - G(s) H₁₂(s) - H(s) -H₂₁(s) - F(s) linearised closed-loop transfer function - _x 2 times spatial frequency of counterphase grating pattern - the ratio (1+s)/(_x)₂ - a the product (1+r)·k - d density of bipolars per unit area     

DNA polymorphism in cytokine genes based on length variation in simple-sequence tandem repeats

The possibility of the involvement of cytokines in the genetic predisposition to various diseases has been suggested by a large variety of studies. However, the study of potential disease linkage of cytokine genes has been hampered by a lack of sufficiently polymorphic markers at the restriction fragment length polymorphism (RFLP) level. We have investigated the distribution, the length polymorphism, the informativeness, and the efficiency of analysis, of simple-sequence tandem repeats in the mouse cytokine genes. Highly polymorphic sequences have been identified in the IL-1, IL-1ra, IL-2, IL-4, IL-6, IL-7, and IFN- genes. The utility and the value of these sequences as gene markers is exemplified by mapping the IL-7 gene to mouse chromosome 3 close to pgk-1ps3 and Car-2 loci and the IFN- gene to chrrmosome 10 near the pg locus. Advantages of short tandemly repeated sequences as genetic markers are discussed in comparison with RFLPs.     

β-structures of polypeptides with L- and D-residues

Summary A series of five alternating poly(leucyl-lysyl) samples with varying amounts of L- and D-residues randomly distributed along the chain, but evenly shared out amongst leucyl and lysyl residues were synthesized by condensation of a mixture of the four diastereoisomeric dipeptidep-nitro-phenylesters. Their behavior in aqueous solution at various ionic strengths was studied by infrared spectroscopy which allowed measurement of the total amount of-structures, and by circular dichroism which gives the excess of L-residues over D-residues in the same structures. Comparison with the properties of the all L-poly(Lys-Leu-Lys-Leu) shows that incorporation of a few D-residues in a L-chain seems to reduce the width of the-sheets obtained in presence of salt. Higher proportions of D-isomers prevent the coil transition from occurring when the ionic strength is increased except for segments containing at least 6 to 7 adjacent residues of the same configuration.     

Genetic exchanges caused by ultraviolet photoproducts in phage λ DNA molecules: The role of DNA replication

Summary Genetic recombination induced by structural damage in DNA molecules was investigated in E. coli K12 () lysogens infected with genetically marked phage . Photoproducts were induced in the phage DNA before infection by exposing them either to 313 nm light in the presence of acetophenone or to 254 nm light. To test the role of the replication of the damaged phage DNA on the frequency of the induced recombination, both heteroimmune and homoimmune crosses were performed.First, samples of a heteroimmune phage imm434 P80 exposed to these treatments were allowed to infect cells lysogenic for prophage cI857 P3. Phage DNA replication and maturation took place, and the resulting progeny phages were assayed for the frequency of P ⁺ recombinants. Recombination was less frequent in infected cells exposed to visible light and in wild type cells able to perform excision repair than in excision-defective lysogens. Therefore, much of the induced recombination can be atributed to the pyrimidine dimers in the phage DNA, the only photoproducts known to be dissociated by photoreactivating enzyme.Second, in homoimmune crosses, samples of similarly treated homoimmune P3 phages were allowed to infect lysogens carrying cI857 P80. Replication of the phage DNA containing ultraviolet photoproducts was repressed by immunity, and was futher blocked by the lack of the P gene product needed for replication. The lysogens were purified and scored for both colony forming ability and for P ⁺ recombinant prophages. The 254 nm photoproducts increased the frequency of recombination in these homimmune crosses, even though phage DNA replication was blocked. Irradiation with 313 nm light and acetophenone M, which produces dimers and unknown photoproducts, was not as effective per dimer as the 254 nm light.It is concluded from these results that certain unidentified 254 nm photoproducts can cause recombination even in the absence of DNA replication. They are not pyrimidine dimers, as they are not susceptible to excision repair or photoreactivation. In contrast, pyrimidine dimers appear to cause recombination only when the DNA containing them undergoes replication.     

Performance of cell immobilized packed bed bioreactor for continuous fermentation of alcohol

Experiments were conducted in a packed bed bio-reactor consisting of entrapped yeast cells in alginate matrix for continuous production of alcohol. The variables include initial substrate level, reactor diameter, diameter of the bead and residence time. The influence of these parameters on the conversion of substrate was studied. The film and pore diffusional effects were observed by varying the column and bead diameters, respectively. The pseudo first order reaction rate constant was calculated and correlated with the bead diameter. The effectiveness factor and the Thiele modulus were estimated. A correlation was proposed for fractional conversion in terms of operating variables. It is possible to predict the residence time required and volumetric productivity achieved in a bioreactor for any given initial substrate concentration at any fractional conversion obtained.List of Symbols a _m m²/kg surface are per unit mass of catalyst particle - D m diameter of the reactor - D _e m²/s effective diffusivity - d m particle diameter - h m bed height - k m/s first order reaction rate constant - k m³/(kg · s) pseudo first order reaction rate constant - k _in m³/(kg · s) intrinsic reaction rate constant, (=K/gh) - k _m m/s mass transfer coefficient - P kmol/(m³ · s) volumetric productivity - Q m³/s flow rate of the feed - S kmol/m³ substrate concentration at any time - S _o kmol/m³ initial substrate concentration - S _p kmol/m³ substrate concentration on the gel bead surface - t s reaction time - T (kg · cat · s)/m³ space time (weight of the biocatalyst/flow rate of the feed) - v kmol/(kg · cat · s) reaction rate - V _pfr m³ volume of the packed bed reactor - X [1-(S/S _o)] fraction of the substrate converted in to product Greek Symbols effectiveness factor - Thiele modulus - kg/m³ density of the catalyst particle - s residence time, (= D² h/4Q) - voidage     

Pepper pathogenesis‐related protein 4c is a plasma membrane‐localized cysteine protease inhibitor that is required for plant cell death and defense signaling

Xanthomonas campestris pv. vesicatoria (Xcv) type III effector AvrBsT triggers programmed cell death (PCD) and activates the hypersensitive response (HR) in plants. Here, we isolated and identified the plasma membrane localized pathogenesis‐related (PR) protein 4c gene (CaPR4c) from pepper (Capsicum annuum) leaves undergoing AvrBsT‐triggered HR cell death. CaPR4c encodes a protein with a signal peptide and a Barwin domain. Recombinant CaPR4c protein expressed in Escherichia coli exhibited cysteine protease‐inhibitor activity and ribonuclease (RNase) activity. Subcellular localization analyses revealed that CaPR4c localized to the plasma membrane in plant cells. CaPR4c expression was rapidly and specifically induced by avirulent Xcv (avrBsT) infection. Transient expression of CaPR4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H₂O₂ and significant induction of some defense‐response genes. Deletion of the signal peptide from CaPR4c abolished the induction of HR cell death, indicating a requirement for plasma membrane localization of CaPR4c for HR cell death. CaPR4c silencing in pepper disrupted both basal and AvrBsT‐triggered resistance responses, and enabled Xcv proliferation in infected leaves. H₂O₂ accumulation, cell‐death induction, and defense‐response gene expression were distinctly reduced in CaPR4c‐silenced pepper. CaPR4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis. These results collectively suggest that CaPR4c plays an important role in plant cell death and defense signaling.     

Dinuclear versus mononuclear ruthenium(II) and osmium(II) complexes as potent mediators of glucose oxidase; crystal structure of [OsCl(4,4′-bpy)(bpy)<Subscript>2</Subscript>]BF<Subscript>4</Subscript>

New and known homo- and heterodinuclear Ru^II and Os^II complexes with 4,4-bipyridine (4,4-bpy), pyrazine, and 4-pyCH=CHpy-4 as bridging ligands (LL) of the type [Cl(bpy)₂M(LL)MCl(bpy)₂]X₂ (bpy=2,2-bipyridine; X=PF₆ or BF₄) have been studied in their capacity to exchange electrons with a reduced active site of glucose oxidase (GO) from Aspergillus niger. Cyclic voltammograms (CVs) of the dimers in the aqueous buffered solution, when compared with CVs of the parent monomeric species [MCl(LL)(bpy)₂]BF₄ and [MCl₂(bpy)₂] which could be generated at pH7, if the dimers undergo monomerization, indicate that the dimers are the dominating species under such conditions. All electrochemically oxidized dinuclear complexes studied show high rates of oxidation of GO reduced by d-glucose and the corresponding observed second-order rate constants are in the range (5–64)×10⁵ M^–1 s^–1 at 25 °C. However, these values are lower than that for the mononuclear complex [OsCl(4,4-bpy)(bpy)₂]BF₄ (1.1×10⁷ M^–1 s^–1), suggesting that potentially two-electron dimeric mediators have no advantage compared with corresponding monomeric complexes of Ru^II and Os^II. The structure of [OsCl(4,4-bpy)(bpy)₂]BF₄ was confirmed by X-ray crystallography. The monodentate 4,4-bpy ligand is coordinated cis to the chloride. Its higher reactivity toward reduced GO is accounted for in terms of the antenna effect of the monodentate 4,4-bpy ligand. The antenna length equals 9.2 Å and matches the depth of the enzyme active site pocket of ca. 10 Å. The mechanism of the antenna effect is discussed     

Increased alpha3-fucosylation of alpha1-acid glycoprotein in Type I diabetic patients is related to vascular function

Diabetic mellitus is attended by the development of endothelial dysfunction which is suggested to be accompanied with a chronic low-degree of inflammation. During a chronic hepatic inflammatory response, specific changes in glycosylation of the acute phase protein ₁-acid glycoprotein (AGP) can be detected. In this report we studied the changes in glycosylation of AGP in more detail and evaluated the relation between a change in glycosylation of AGP and urinary albumin secretion in Type I diabetic patients. The glycosylation of AGP, studied by crossed affinity immunoelectrophoresis (CAIE) and high pH anion exchange chromatography with pulse amperometric detection (HPAEC-PAD), showed an increase in 3-fucosylation. Staining with an antibody against sialyl Lewis^x (sLe^x) implied that part of the 3-fucosylation was present in a sLe^x-conformation. In the group of Type I diabetic patients with increased urinary albumin excretion, a significant increase in 3-fucosylation of AGP (p[emsp4 ]<[emsp4 ]0.0005) could be detected. Therefore, the increased 3-fucosylation of AGP can be used as an additional marker for the development of vascular complications in Type I diabetic patients.