Trypanosoma brucei rhodesiense and T. b. gambiense are known causes of human African trypanosomiasis (HAT), or "sleeping sickness," which is deadly if untreated. We previously reported that a specific inhibitor of trypanosome alternative oxidase (TAO), ascofuranone, quickly kills African trypanosomes in vitro and cures mice infected with another subspecies, non-human infective T. b. brucei, in in vivo trials. As an essential factor for trypanosome survival, TAO is a promising drug target due to the absence of alternative oxidases in the mammalian host. This study found TAO expression in HAT-causing trypanosomes; its amino acid sequence was identical to that in non-human infective T. b. brucei. The biochemical understanding of the TAO including its 3 dimensional structure and inhibitory compounds against TAO could therefore be applied to all three T. brucei subspecies in search of a cure for HAT. Our in vitro study using T. b. rhodesiense confirmed the effectiveness of ascofuranone (IC(50) value: 1 nM) to eliminate trypanosomes in human infective strain cultures.
BACKGROUND: Xanthomonas oryzae pv. oryzae causes bacterial blight of rice (Oryza sativa L.), a major disease that constrains production of this staple crop in many parts of the world. We report here on the complete genome sequence of strain PXO99A and its comparison to two previously sequenced strains, KACC10331 and MAFF311018, which are highly similar to one another. RESULTS: The PXO99A genome is a single circular chromosome of 5,240,075 bp, considerably longer than the genomes of the other strains (4,941,439 bp and 4,940,217 bp, respectively), and it contains 5083 protein-coding genes, including 87 not found in KACC10331 or MAFF311018. PXO99A contains a greater number of virulence-associated transcription activator-like effector genes and has at least ten major chromosomal rearrangements relative to KACC10331 and MAFF311018. PXO99A contains numerous copies of diverse insertion sequence elements, members of which are associated with 7 out of 10 of the major rearrangements. A rapidly-evolving CRISPR (clustered regularly interspersed short palindromic repeats) region contains evidence of dozens of phage infections unique to the PXO99A lineage. PXO99A also contains a unique, near-perfect tandem repeat of 212 kilobases close to the replication terminus. CONCLUSION: Our results provide striking evidence of genome plasticity and rapid evolution within Xanthomonas oryzae pv. oryzae. The comparisons point to sources of genomic variation and candidates for strain-specific adaptations of this pathogen that help to explain the extraordinary diversity of Xanthomonas oryzae pv. oryzae genotypes and races that have been isolated from around the world.
Lipase-catalyzed acetylation of 2-alkanol with vinyl acetate has been studied kinetically using Burkholderia cepacia lipase (BCL), enantiomerically pure (R)- and (S)-2-alkanols and different organic solvents. The rate equation was derived by the steady state method for the simplified mechanism. The second order rate constants (k(R) and k(S)) for (R)- and (S)-2-alkanols were evaluated from the slopes of the double reciprocal plots, v(-1) vs. [2-alkanol](-1), where v is the initial rate of the reaction. The log k(R) value increased with the solvent hydrophobicity log P, where P is a partition coefficient of a given solvent between octanol and water. The log k(S) value also increased with log P except the bulky solvents such as 1,4-dioxane and cyclohexane, in which the rates were faster than those expected from the log k(S) vs. log P plot. The slope of log k(S) vs. log P plot was larger than that for (R)-2-alkanol. Thus, log E (E=k(R)/k(S): enantioselectivity) decreased with log P except the bulky solvents. The rate constants and the enantioselectivity were different depending on the structure (carbon number CN) of 2-alkanol. The log E vs. CN plot was minimized at CN=8 and 10 and the log k(S) vs. CN plot maximized at CN=8 and 10. In contrast the log k(R) vs. CN plot showed a different feature from the log E vs. CN plot. These facts suggest that dependence of E on CN is more strongly affected by the reactivity of (S)-2-alkanol than that of (R) isomer in this acetylation.
Title: [Optical resolution of 2-alkanol by lipase-catalyzed acetylation with vinyl acetate in packed-bed reactor with recycling system] Yanagishita H, Sakaki K, Hirata H Ref: J Oleo Sci, 56:137, 2007 : PubMed
The lipase-catalyzed acetylation of 2-alkanol with vinyl acetate was studied using Burkholderia cepacia lipase (BCL), three alcohol and three organic solvents in a packed-bet reactor with a recycling system (flow method). The optical resolution data were found in agreement with those of the batch method in which BCL was suspended in the substrate solution. Repeated reaction results clearly indicated BCL in the packed-bed to be quite stable and to be usable for at least 50 reaction runs or to remain effective for as long as two months in the water-insoluble solvents such as hexane and 1,2-dichloroethane. In the reaction using a water-soluble solvent such as acetonitrile, the catalytic power of BCL showed only a 1% decrease of conversion per run or solvent recycling possibly owing to compression of BCL in the bed although enantioselectivity was independent of the number of reaction repetitions. The present method showed thus be applicable to kinetic resolution by enzyme-catalyzed acylation in hydrophobic organic solvents with no waste of enzyme.
Using an animal model of forebrain ischemia in spontaneously hypertensive rats (SHR) by 3-h bilateral carotid occlusion, and various indices of the cerebral cholinergic system were assessed for periods up to 24 weeks. The lesions observed histologically in the hippocampus of SHR 2 weeks after ischemia were less severe than those in the frontal cortex. Marked elevation of acetylcholine concentration was transiently observed in the frontal cortex, hippocampus and thalamus + midbrain at 2 weeks, and in the striatum at 1-4 weeks after ischemia. Choline acetyltransferase activity remained unchanged in all regions throughout the experimental period except for a minimal decrease in the frontal cortex at 4 weeks. Choline esterase (ChE) activity was slightly decreased in the frontal cortex at 2-4 weeks after ischemia but recovered by 8 weeks. A decrease in the hippocampus was seen at 8 weeks. The B(max) for the M1-receptor was significantly reduced by 2 weeks in the frontal cortex and by 4 weeks in the hippocampus. Low B(max) values in both regions persisted through week 24. These delayed hippocampal changes in the ChE activity and M1-receptor in SHR were similar to those of the very much delayed changes in M1-receptor previously reported in the gerbil model for transient ischemia. In contrast, Wistar-Kyoto rats (WKY), used as normotensive controls, exhibited no histological or biochemical changes for up to 24 weeks. The difference between SHR and WKY may depend on the more severe cerebral blood flow depletion during carotid ligation in the former. The chronic state of SHR after the transient ischemia may be a useful pathophysiological model for human cerebral infarctions with hypertension.
Title: Effects of the acetylcholinesterase inhibitor ENA-713 on ischemia-induced changes in acetylcholine and aromatic amine levels in the gerbil brain Tanaka K, Ogawa N, Asanuma M, Hirata H, Kondo Y, Nakayama N, Mori A Ref: Archives Internationales de Pharmacodynamie et de Therapie, 323:85, 1993 : PubMed
The effects of a new acetylcholinesterase inhibitor, ENA-713, on ischemia-induced changes in acetylcholine, monoamines, and their metabolites, were studied in the gerbil. ENA-713 (0.2 mg/kg) or saline was administered intraperitoneally to gerbils 30 min before induction of cerebral ischemia by bilateral carotid occlusion. Pretreatment with ENA-713 mitigated the ischemia-induced abnormalities of the cholinergic, dopaminergic and serotoninergic systems in the gerbil brain, although it had virtually no effect on acetylcholine, monoamines, or their metabolites in any region of the normal gerbil brain. These findings suggest that ENA-713 has beneficial effects against ischemia-induced cerebral disorders. Thus, ENA-713 seems to be promising as a preventive or therapeutic agent for cerebrovascular dementia due to cerebral ischemia and might be useful for the treatment of Alzheimer-type dementia which is associated with multiple neurotransmitter abnormalities in the brain.
