Strain‐specific consumption and transformation of alga‐derived dissolved organic matter by members of the Limnohabitans‐C and Polynucleobacter‐B clusters of Betaproteobacteria

We investigated changes in quality and quantity of extracellular and biomass‐derived organic matter (OM) from three axenic algae (genera Rhodomonas, Chlamydomonas, Coelastrum) during growth of Limnohabitans parvus, Limnohabitans planktonicus and Polynucleobacter acidiphobus representing important clusters of freshwater planktonic Betaproteobacteria. Total extracellular and biomass‐derived OM concentrations from each alga were approximately 20 mg l^?1 and 1 mg l^?1 respectively, from which up to 9% could be identified as free carbohydrates, polyamines, or free and combined amino acids. Carbohydrates represented 54%–61% of identified compounds of the extracellular OM from each alga. In biomass‐derived OM of Rhodomonas and Chlamydomonas 71%–77% were amino acids and polyamines, while in that of Coelastrum 85% were carbohydrates. All bacteria grew on alga‐derived OM of Coelastrum, whereas only Limnohabitans strains grew on OM from Rhodomonas and Chlamydomonas. Bacteria consumed 24%–76% and 38%–82% of all identified extracellular and biomass‐derived OM compounds respectively, and their consumption was proportional to the concentration of each OM compound in the different treatments. The bacterial biomass yield was higher than the total identifiable OM consumption indicating that bacteria also utilized other unidentified alga‐derived OM compounds. Bacteria, however, also produced specific OM compounds suggesting enzymatic polymer degradation or de novo exudation.     

Effects of α,β-methylene-adenosine-5′-diphosphate on blood platelet aggregation

The effects on platelet aggregation of α,β-methylene-adenosine-5′-diphosphate (Ado-PCP) have been investigated. Using human citrated platelet-rich plasma it has been shown that: (i) at concentrations of 10^?3 M or higher Ado-PCP is able to induce platelet aggregation; (ii) the rate of Ado-PCP-induced aggregation increases on raising the pH of platelet-rich plasma above the pK_a for the secondary phosphonyl dissociation of Ado-PCP; (iii) at concentrations from 1 · 10^?4 to 5 · 10^?4 M Ado-PCP does not cause platelet aggregation itself, but it inhibits ADP-induced aggregation. This inhibition is also observed in washed platelet suspensions. The data suggest that Ado-PCP acts at the same site on the platelet membrane as does ADP and that ADP to AMP transformation is not a prerequisite for the process of aggregation. The observed effect of pH on the rate of Ado-PCP induced aggregation suggests that the ionization state of a nucleotide terminal acid group is important in the process of aggregation.     

Possible role of histidine in the L-proline transport system of Saccharomyces cerevisiae

The L-proline transport system of Saccharomyces cerevisiae is shown to be specifically inactivated upon incubation of intact yeast cells with the histidine modifier diethylpyrocarbonate. The extent of inactivation is half-maximum at 0.5 mM diethylpyrocarbonate for an incubation of 2 min at 30 degrees C and pH 6.0. Under the same conditions, the time dependence of inactivation is monophasic with the second-order rate constant of 5.5 M-1 X s-1 and the maximum rate Jmax of L-proline transport is lowered by about 50%, while the KT value remains unchanged. Moreover, L-proline afforded significant protection against diethylpyrocarbonate inactivation. The complete reactivation of a partially inactivated L-proline transport system by neutral hydroxylamine and the elimination of the possibility that the modification of other amino acid residues are responsible for the inactivation, suggested that the transport protein inactivation occurs solely by a modification of histidine residues.     

Campylobacter sepsis with multiple organ failure in IgG subclass deficiency

Some patients with immunodeficiency develop clinical features of autoimmune disorders. A previously asymptomatic antibody deficiency can underlie the development of autoimmune diseases and a severe course of infection, with a risk of sepsis; such cases are known in selective IgA deficiency. On the other hand, little information is available on selective IgG subclass deficiencies. An unexpectedly severe course of Campylobacter infection in a 19-year-old woman with a previously undiagnosed complex immune disorder, including selective IgG1 immunodeficiency, Hashimoto's autoimmune thyroiditis with hypothyroidism combined with Addison's disease presumably due to autoimmune adrenalitis, autoimmunity and allergy is described. The pathophysiological mechanisms of autoimmunity in latent humoral defects are discussed.     

Diagnoses of and illustrated key to the species of <Emphasis Type="Italic">Ixodes</Emphasis> Latreille, 1795 (Acari: Ixodidae) from Brazil

The current Brazilian Ixodes fauna is composed of the following eight species: I. amarali Fonseca, 1935; I. aragaoi Fonseca, 1935; I. auritulus Neumann, 1904; I. fuscipes Koch, 1844; I. loricatus Neumann, 1899; I. luciae Sénevet, 1940; I. paranaensis Barros-Battesti, Arzua, Pichorim &; Keirans, 2003; and I. schulzei Aragão &; Fonseca, 1951. Further studies are needed to establish the taxonomic status of I. serrafreirei Amorim, Gazeta, Bossi &; Linhares, 2003, a recently proposed species based solely on the nymphal stage. We present an up-to-date key to adults of the currently valid Brazilian species of Ixodes based on scanning electron microscopy. The relationships between Brazilian and other Neotropical Ixodes are also discussed.     

Seasonal morphological variations in bird schistosomes

The present work is a contribution to the systematics of Bilhorziello and Dendritobilharzio. Wildfowl was killed in hunting seasons or found dead in Champagne-Ardenne region, France, and autopsied with focus on schistosomes. Seven Anas plotyrhynchos (mallards), one Ardeo cinerea (grey heron) and two Cygnus olor (mute swans) were parasitized by Bilharziella. One C. olor was parasitized by Dendritobilharzia. Depending on season and hosts, various morphological forms of Bilharziello suggesting several species were observed. The differences in male and female worms concerned the morphology of genital apparatus, the spination on suckers, the body size and proportions. However, the comparison of DNA sequences led to a conclusion that these forms belonged to one species, Bilharziella polonica (Kowalewski, 1895). The morphological features and the body sizes of our samples of Dendritobilharzia seemed to differ from the type species of D. pulverulenta (Braun, 1901). Nevertheless, molecular analysis confirmed identity. We hypothesize that the differences in Bilharziella and Dendritobilharzia might be linked to internal host factors (e.g. hormonal levels), and influenced by season, host, and worm age. The definition of the genera Bilharziello and Dendritobilharzio was amended.     

Enhancement of Isoflavone Synthase Activity by Co-expression of P450 Reductase from Rice

Plant cytochrome P450s interact with a flavoprotein, NADPH-cytochrome P450 reductase (CPR), to transfer electrons from NADPH. The gene for rice P450 reductase (RCPR) was cloned and expressed in Saccaromyces cerevisiae, where the specific activity of the expressed RPCR was 0.91 U/mg protein. When isoflavone synthase gene (IFS) from red clover, used as a model system of plant cytochrome P450, was co-expressed with RCPR in yeast, the production of genistein from naringein increased about 4.3-fold, indicating that the RCPR efficiently interacts with cytochrome P450 to transfer electrons from NADPH.     

Tree species and position matter: the role of pests for survival of other insects

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