Inter-laboratory validation studies of analytical method for determination of chloramphenicol in royal jelly

Inter-laboratory validation studies were conducted in 6 laboratories to validate the analytical method for determination of chloramphenicol in royal jelly. Chloramphenicol spiked at the levels of 0.1 and 0.5 ppm was analyzed. Mean recoveries were 89 and 89%, reproducibility relative standard deviations (RSD(R)) were 10.5 and 6.8%, HORRAT(R) values were 0.5 and 0.4. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 89 and 84%, RSD(R) were 9.8 and 12.3%, and HORRAT(R) values were 0.5 and 0.7. The determination limit was 0.05 ppm. These results show that this method has good performance.     

A study on phenoxy-resin esters of cinnamylideneacetic acid and its derivatives

Photocrosslinkable polymers were prepared from phenoxy resin which was photoactivated by esterifying cinnamylideneacetic acid, α-cyanocinnamylideneacetic acid or cinnamylidenepyruvic acid. Relative sensitivities and spectral sensitivities of these polymers were determined by comparing with the phenoxy resin ester of cinnamic acid. It was found that the polymer which was photo-activated with cinnamylidenepyruvic acid had the highest photosensitivity and its spectral sensitivity extended up to 500 nm without the aid of any additional sensitizing dye. The mechanism of the photocrosslinking of these polymers was also considered.     

Design and development of optical fiber joining techniques forefficient construction of aerial distribution cable systems

Two new optical fiber joining techniques have been developed for aerial distribution cables. One employs a compact mass-fusion splicer and the other involves a small mechanical splice. This paper describes their design and performance. These techniques are excellent for use in aerial sites and enable aerial distribution cable systems to be constructed efficiently. They will be useful for the economical construction of optical access networks for fiber-to-the-home     

Visualizing language evolution as an emergent phenomenon based on biological evolution and learning

From the perspective of artificial life, language can be viewed as a complex adaptive system emerging from linguistic interactions between individuals. Language and the human brain have evolved in parallel and by interacting with each other. In this study, we propose a model of language evolution based on biological evolution and learning. In our model, the linguistic space is expressed in the polar coordinate system in which each possible language is expressed as a point. We conduct evolutionary experiments based on this model, and visualize the results in linguistic space. The distribution trajectory of innate linguistic abilities shows the diversification and complexity of language growth. In the extended experiment, in which the angular coordinates represent the additional effect of the cost of plasticity, we observe a general tendency that the cost of plasticity evolves to become smaller. However, it never evolves to be zero, which might suggest that some cost of plasticity producing the Baldwin effect is adaptive in language evolution.     

Identification of 3,4-Dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine Derivatives as Novel Selective Inhibitors of Plasmodium falciparum Dihydroorotate Dehydrogenase

Plasmodium falciparum’s resistance to available antimalarial drugs highlights the need for the development of novel drugs. Pyrimidine de novo biosynthesis is a validated drug target for the prevention and treatment of malaria infection. P. falciparum dihydroorotate dehydrogenase (PfDHODH) catalyzes the oxidation of dihydroorotate to orotate and utilize ubiquinone as an electron acceptor in the fourth step of pyrimidine de novo biosynthesis. PfDHODH is targeted by the inhibitor DSM265, which binds to a hydrophobic pocket located at the N-terminus where ubiquinone binds, which is known to be structurally divergent from the mammalian orthologue. In this study, we screened 40,400 compounds from the Kyoto University chemical library against recombinant PfDHODH. These studies led to the identification of 3,4-dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine and its derivatives as a new class of PfDHODH inhibitor. Moreover, the hit compounds identified in this study are selective for PfDHODH without inhibition of the human enzymes. Finally, this new scaffold of PfDHODH inhibitors showed growth inhibition activity against P. falciparum 3D7 with low toxicity to three human cell lines, providing a new starting point for antimalarial drug development.     

Dissimilatory nitrate reduction metabolisms and their control in fungi

Most fungi grow under aerobic conditions by generating ATP through oxygen respiration. However, they alternatively express two pathways of dissimilatory nitrate reduction in response to environmental oxygen tension when the oxygen supply is insufficient. The fungus Fusarium oxysporum expressed the pathway of respiratory nitrate denitrification that is catalyzed by the sequential reactions of nitrate reductase and nitrite reductase. These enzymes are coupled with ATP generation through the respiratory chain and produce nitric oxide. Fungal nitric oxide reductase uses NADH as the direct electron donor in contrast to bacterial systems and thus might function in regeneration of NAD+ and detoxification of the toxic radical, nitric oxide. Another pathway of nitrate dissimilation by fungi reduces nitrate to ammonium and couples acetogenic reaction with substrate-level phosphorylation. This metabolic mechanism is also in feature of a variety of fungi and it is called ammonia fermentation. Thus, fungi adapt to various aerated conditions using these pathways of nitrate dissimilation in addition to conventional oxygen respiration.     

Genetic engineering using fungal flavohemoglobin for constructing Pseudomonas stutzeri strain emitting less nitrous oxide

Most denitrifiers produce the greenhouse gas nitrous oxide (N2O) due to insufficient anaerobiosis. We constructed a recombinant Pseudomonas stutzeri strain producing Fusarium oxysporum flavohemoglobin (fhb) and found that it emitted less N2O than the wild-type strain under aerobic and anaerobic conditions. The rate of N2 production was higher than in the wild-type strain after the depletion of oxygen in culture, suggesting that fhb enhanced the reduction of N2O to N2. The strain is the first recombinant bacterial denitrifier that reduces N2O production.     

A comprehensive evaluation of the methods for evolving a cooperative team

This article focuses on the techniques of evolutionary computation for generating players performing tasks cooperatively. However, in using evolutionary computation for generating players performing tasks cooperatively, one faces fundamental and difficult decisions, including the one regarding the so-called credit assignment problem. We believe that there are some correlations among design decisions, and therefore a comprehensive evaluation of them is essential. We first list three fundamental decisions and possible options in each decision in designing methods for evolving a cooperative team. We find that there are 18 typical combinations available. Then we describe the ultimately simplified soccer game played on a one-dimensional field as a testbed for a comprehensive evaluation for these 18 candidate methods. It has been shown that some methods perform well, while there are complex correlations among design decisions. Also, further analysis has shown that cooperative behavior can be evolved, and is a necessary requirement for the teams to perform well even in such a simple game. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005