Dispersal ofAleochara bilineata [Col.: Staphylinidae] following inundative releases in urban gardens

Aleochara bilineata (Gyllenhal) [Coleoptera: Staphylinidae] is a common predator and endoparasite of root maggot [Diptera: Anthomyiidae] in both commercial crops and home gardens. To test dispersal activity ofA. bilineata in home gardens, marked beetles were released at rates of 0 and 1,000 in 1987 and 0, 250, 500, and 1,000/gardens/wk in 1988. Three percent of marked beetles were recaptured in release gardens. NaturalA. bilineata populations were very small in all gardens, and there was no detectable increase from 1987 to 1988. Recaptures were proportional to release rates. There was no significant difference in recapture rates between sexes. Recaptures and non-uniform distributions of markedA. bilineata in control gardens revealed that they were capable of flying at least 5 km under urban conditions, and of selecting particular gardens as suitable mating, foraging, and oviposition sites.      

Stereochemical considerations in the enzymatic phosphorylation and antiviral activity of acyclonucleosides. I. Phosphorylation of 2'-nor-2'-deoxyguanosine

The antiviral compound 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine (2'-nor-2'-deoxyguanosine, 2'-NDG) is phosphorylated by the HSV-1-induced thymidine kinase to the monophosphate (2'-NDG-MP) and this is further phosphorylated by cellular kinases to the triphosphate (2'-NDG-TP) which is a potent inhibitor of DNA polymerases. Since phosphorylation of 2'-NDG creates a chiral center in the molecule, it was of interest to examine whether both monophosphate enantiomers were produced by the viral thymidine kinase, whether they both could be further phosphorylated by cellular kinases and, if so, whether the respective triphosphates were equally inhibitory to the DNA polymerases. The time course of the phosphorylation by GMP kinase of a chemically synthesized, racemic 2'-NDG-MP was compared to that of a 2'-NDG-MP preparation obtained by enzymatic phosphorylation of 2'-NDG with HSV-1 thymidine kinase. The results indicated that the two enantiomeric monophosphates were phosphorylated by GMP kinase with different rates and that phosphorylation of 2'-NDG by HSV-1 thymidine kinase gave only one of the isomers, whose structure was determined to be S. Both enantiomeric diphosphates were further phosphorylated to the respective triphosphates and it was shown that, in contrast to the triphosphate obtained from the 2'-NDG-MP prepared by viral thymidine kinase which was a potent inhibitor of HSV-1 DNA polymerase, the triphosphate obtained from the slow-reacting R isomer had little or no inhibitory activity against this enzyme.     

5-Halo-6-phenyl pyrimidinones and 8-substituted guanosines: biological response modifiers with similar effects on B cells

5-Halo-6-phenyl pyrimidinones, represented by 2-amino-5-bromo-6-phenyl-4(3H)-pyrimidinone (ABPP) and 2-amino-5-iodo-6-phenyl-4(3H)-pyrimidinone (AIPP), and 8-substituted guanosines, represented by 8-bromoguanosine (8-BrGuo) and 8-mercaptoguanosine (8-MGuo), are well-documented biological response modifiers. We have found that these substituted pyrimidinones and guanosines are very similar in their abilities to activate B cells. ABPP, AIPP, 8-BrGuo, and 8-MGuo induced murine B cells to polyclonally proliferate and differentiate in vitro. The maximal B-cell response levels and the kinetics of the responses elicited with both classes of compounds were comparable; however, ABPP and AIPP were approximately 10-fold more potent than 8-BrGuo and 8-MGuo. An additional similarity observed between the two classes was that polyclonal activation of B cells by ABPP, AIPP, 8-BrGuo, and 8-MGuo was limited to large B cells which had probably been activated previously in vivo. This is in contrast to lipopolysaccharide which is capable of inducing both large, activated B cells and small, resting B cells to proliferate and differentiate. Although substituted pyrimidinones and guanosines were not able to induce new DNA synthesis or antibody production in small B cells, both classes of compounds increased the expression of Ia antigens on the surface of both small and large B cells. These data, together with the recent observations that 8-BrGuo, like ABPP and AIPP, can stimulate NK and cytotoxic macrophage activity via the induction of interferon, strongly suggest that 5-halo-6-phenyl pyrimidinones and 8-substituted guanosines belong to the same structural class of biological response modifiers. Thus, the residues held in common by these two classes of stimulators may interact with the same cellular constituent in the target cells.     

Growth inhibition of Clostridium thermocellum by carboxylic acids: A mechanism based on uncoupling by weak acids

Summary The inhibition of Clostridium thermocellum strains by acetate and other organic acids (propionate, butyrate) can be explained by a model based on the chemiosmotic theory and uncoupler action. It is proposed that the charged permeant species in the process of anion exclusion is the dimer HA _- ² . Evidence for this mechanisms is provided by ³¹P-NMR studies of whole cells and cell extracts.Abbreviations CM4-Cb CM4-cellobiose - EPC⁵⁰ equipotency concentration - P _m bilayer partition coefficient - ka acid dissociation constant     

The reactivity of tetracarbonylnickel encapsulated in zeolite X. A case history of intrazeolite coordination chemistry.

Zeolite X shows a high capacity for tetracarbonylnickel (up to 28 weight percent) such that complete pore filling with ‘liquid like’ material takes place. The adsorbed material may be removed simply by evacuation at room temperature. Partial decomposition of the Ni(CO)₄ occurs on standing at room temperature under N₂. The resultant orange species is highly reactive and has spectroscopic properties consistent with a coordinatively unsaturated ‘Ni(CO)₃’. Complete and irreversible decomposition by heating to 200 °C in vacuo gives a black zeolite, with an undefined metal phase, which is unreactive towards carbon monoxide. Reaction of the zeolite supported Ni(CO)₄ with various phosphorus ligands is highly dependent on the original loading level as well as the physical size of the ligands involved. At low loadings two kinds of reactivity are observed: 1) With ligands too large to gain access to the zeolite crystal interior, reaction occurs only in solution and so drags the Ni(CO)₄ from the zeolite: 2) With smaller ligands, reaction takes place inside the zeolite cages leading to well-defined, encapsulated, ship-in-bottle complexes which have a stoichiometry dictated by the available space in the cages. At high loading levels, pore blocking phenomena lead to inhomogeneous distributions of encapsulated complexes wherein a complete shell of phosphorous ligand substituted nickel carbonyl species forms at the crystal surface layers and prevents further reaction deeper inside the crystal. The reactivity with large phosphines has been used to study the diffusion of Ni(CO)₄ from the zeolite. Monitoring the appearance of the Ni(CO)₃L (where L = phosphine) by 31-P NMR of the supernatant solution shows that Ni(CO)₄ leaves the zeolite with a first order rate constant of at least 2 × 10^?2 sec^?1 at 298 K.     

BOOK REVIEWS

Accidental hypothermia was studied in 11 patients, five of whom died. This condition occurs spontaneously, usually in a cold environment, and should be suspected in the comatose hypotensive patient. It is easily missed because regular clinical thermometers do not record extremely low body temperatures. It is distinguished from other forms of hypothermia by the very low body temperature and by the absence of recognized causes of hypothermia. Ten of the 11 patients were either alcoholic or diabetic. Intravascular thrombosis was the most common complication leading to death.     

NMR characterization of an engineered domain fusion between maltose binding protein and TEM1 β‐lactamase provides insight into its structure and allosteric mechanism

RG13 is a 72 kDa engineered allosteric enzyme comprised of a fusion between maltose binding protein (MBP) and TEM1 β‐lactamase (BLA) for which maltose is a positive effector of BLA activity. We have used NMR spectroscopy to acquire [¹⁵N, ¹H]‐TROSY‐HSQC spectra of RG13 in the presence and absence of maltose. The RG13 chemical shift data was compared to the published chemical shift data of MBP and BLA. The spectra are consistent with the expectation that the individual domain structures of RG13 are substantially conserved from MBP and BLA. Differences in the spectra are consistent with the fusion geometry of MBP and BLA and the maltose‐dependent differences in the kinetics of RG13 enzyme activity. In particular, the spectra provide evidence for a maltose‐dependent conformational change of a key active site glutamate involved in deacylation of the enzyme‐substrate intermediate. Proteins 2010. © 2009 Wiley‐Liss, Inc.     

2'-Deoxy-2'-halonucleotides as alternate substrates and mechanism-based inactivators of Lactobacillus leichmannii ribonucleotide reductase

The interaction of the ribonucleoside-triphosphate reductase of Lactobacillus leichmannii with various 2'-halogenated ribo- and arabinonucleoside triphosphates has been investigated. All analogues examined acted as mechanism-based inactivators of the enzyme, producing base, triphosphate, and halide. In all cases, the inactive enzyme had developed the distinctive chromophore at 320 nm that is characteristic of enzyme inactivated by 2-methylene-3(2H)-furanone. The striking similarities between these results and those previously reported for the inactivation of this enzyme by 2'-chloro-2'-deoxyuridine triphosphate suggest a common reaction path for all 2'-halonucleotides. In the pyrimidine series, it was found that 2'-fluoro- and 2'-chloronucleotides partitioned between inactivation and formation of the normal reduction product 2'-deoxynucleotide. Normal reduction predominated with 2'-fluoronucleotides, whereas it was a minor pathway for 2'-chloro-2'-deoxyuridine triphosphate. With 2'-chloro-2'-deoxyuridine triphosphate, the relative partitioning between the two modes was pH dependent: the amount of 2'-deoxyuridine triphosphate formed increased 2.8-fold upon changing from pH 6.1 to pH 8.3. The ability of 2'-arabinohalonucleotides to inactivate ribonucleotide reductase and the variation of partitioning of the pyrimidine analogues with leaving group and reaction pH are consistent with our radical cation hypothesis and support the proposal that the difference between normal catalysis and inactivation is related to the protonation state of the reductase.     

Phenylacetic acid derivatives as hPPAR agonists

Beginning with the weakly active lead structure 1, a new series of hPPAR agonists was developed. In vivo glucose and triglyceride lowering activity was obtained by homologation and oxamination to 3, then conversion to substituted benzisoxazoles 4 and 5. Further manipulation afforded benzofurans 6 and 7. Compound 7 was of comparable potency as a glucose and triglyceride lowering agent in insulin resistant rodents to BRL 49653.     

Gram scale purification and preparation of rabbit liver zinc metallothionein.

A simplified procedure for purifying gram quantities of rabbit liver metallothionein (MT) using gel filtration and anion exchange chromatography is presented. The MT purification made use of anion exchange batch elution chromatography which greatly shortened the procedure. Quantitation techniques for use with crude and purified MT are discussed. This paper also describes the preparation of large amounts of ZnMT from Cd,ZnMT.