Enhanced plasma ghrelin levels in rats with streptozotocin-induced diabetes

Human saliva, which contains nitrite, is normally mixed with gastric juice, which contains ascorbic acid (AA). When saliva was mixed with an acidic buffer in the presence of 0.1 mM AA, rapid nitric oxide formation and oxygen uptake were observed. The oxygen uptake was due to the oxidation of nitric oxide, which was formed by AA-dependent reduction of nitrite under acidic conditions, by molecular oxygen. A salivary component SCN⁻ enhanced the nitric oxide formation and oxygen uptake by the AA/nitrite system. The oxygen uptake by the AA/nitrite/SCN⁻ system was also observed in an acidic buffer solution. These results suggest that oxygen is normally taken up in the stomach when saliva and gastric juice are mixed.     

Improvement in thermostability and psychrophilicity of psychrophilic alanine racemase by site-directed mutagenesis

A psychrophilic alanine racemase from Bacillus psychrosaccharolyticus has a higher catalytic activity than a thermophilic alanine racemase from Bacillus stearothermophilus even at 60 °C in the presence of pyridoxal 5′-phosphate (PLP), although the thermostability of the former enzyme is lower than that of the latter one [FEMS Microbial. Lett. 192 (2000) 169]. In order to improve the thermostability of the psychrophilic enzyme, two hydrophilic amino acid residues (Glu150 and Arg151) at a surface loop surrounding the active site of the enzyme were substituted with the corresponding residues (Val and Ala) in the B. stearothermophilus alanine racemase. The mutant enzyme (ER150,151VA) showed a higher thermostability, and a markedly lower K_m value for PLP, than the wild type one. In addition, the catalytic activities at low temperatures and kinetic parameters of the two enzymes indicated that the mutant enzyme was more psychrophilic than the wild type one. Thus, the psychrophilic alanine racemase was improved in both psychrophilicity and thermostability by the site-directed mutagenesis. The mutant enzyme may be useful for the production of stereospecifically deuterated NADH and various -amino acids.     

Hormonal control of storage protein synthesis and uptake by the fat body in the silkworm, Bombyx mori

The female silkworm, Bombyx mori, rapidly accumulates two storage proteins, that are synthesized by the fat body, in the haemolymph during the feeding stage of the last-larval instar, and then sequesters them from the haemolymph into fat body during the larval-pupal transformation.The rapid synthesis and uptake of storage proteins by the fat body are shown to be induced by allatectomy in the early-penultimate larval instar. A juvenile hormone analogue, methoprene, is highly effective in inhibiting the allatectomy-induced synthesis, and, in a higher dosage, further blocks the uptake. Allatectomy in the late-penultimate larval instar shortly before moulting does not enhance the storage protein synthesis, but causes the uptake to occur two days earlier in the last-larval instar. Injection of 20-hydroxyecdysone is not stimulatory for synthesis of the proteins, but is effective to induce their uptake. Starvation during the early last-larval instar completely blocks the synthesis.From these results, it is suggested that storage protein synthesis is induced in the absence of juvenile hormone by some supplementary stimulus, possibly the supply of nutrient after feeding, and uptake is induced by ecdysteroids after a decline in the juvenile hormone level.     

Introduction of an active enzyme into permeable cells of Escherichia coli: acquisition of ultraviolet light resistance by uvr mutants on introduction of T4 endonuclease V.

Summary Plasmolysed cells of Escherichia coli N212 (uvrA recA) acquired ultraviolet resistance when the cells were exposed to high concentrations of T4 endonuclease V. With increasing concentrations of T4 enzyme, survivals of plasmolysed cells after ultraviolet irradiation increased while colony-forming ability of unirradiated plasmolysed cells was not significantly affected by the enzyme treatment. Under appropriate conditions more than 200 fold increase in survivals was observed. When plasmolysed cells were treated with a pre-heated enzyme preparation or enzyme fractions derived from T4v ₁(endonuclease V-deficient mutant)-infected cells, only little or no reactivation took place.Permeabilization of cells prior to the enzyme treatment was essential for the effective reactivation. Treatment of intact cells with the T4 enzyme did not cause any reactivation. Cells treated with 20 mM EGTA or 50 mM CaCl₂ in cold were reactivated to certain extents by the enzyme, but the extents of the reactivation were far less compared to those of plasmolysed cells.Plasmolysed cells of strains carrying a mutation in one of uvrA, uvrB and uvrC genes were reactivated by introduction of T4 endonuclease V, as was the uvrA recA double mutant. UvrD mutants were also reactivated, but rather slightly. However, wild type strain as well as strains having a mutation in recA or polA gene were not reactivated. From these results it was suggested that T4 endonuclease V, taken up into permeable cells, can function in vivo to replace defective functions, which are controlled by the uvr genes. The conditions established in the present study may be used for introduction of other proteins into viable bacterial cells.     

Differentiation-associated changes in membrane proteins of mouse myeloid leukemia cells

The mouse myeloid leukemia cell line (M1) is known to differentiate in vitro into macrophages and granulocytes upon treatment with various inducer including mouse ascitic fluid. Changes of cell surface proteins during differentiation of M1 cells were analyzed by the lactoperoxidase-catalyzed radioiodination method and SDS-polycrylamide slab gel electrphoresis. Treatment of the cells with ascitic fluid changed the electrophoretic pattern of the iodinated proteins, the prominent change being the appearance of a new protein with a molecular weight of 180 000 (P180). Iodinated P180 was also detected in normal macrophages in granulocytes, which are similar to differentiated M1 cells. This protein was metabolically labeled with l-[¹⁴C]fucose, increasing with the period of the treatment. P180 was not expressed on ascitic fluid-treatment of a resistant clone of M1 cells that could not be induced to differentiate. These results indicate that P180 is a glycoprotein that is exposed on the outer surface of differentiated M1 cells, and that its expression is associated with differentiation of the cells.P180 was solubilized from ¹²⁵I-labeled macrophages with detergents bound to concanavalin A-Sepharose. This suggests that P180 is one of the receptors for concanavalin A. Therefore, P180 may contribute partly to the increases in agglutinability by concanavalin A and in the number of concanavalin A binding sites on the surface of M1 cells, which are known to be associated with differentiation of M1 cells.     

Indoor environmental study and post occupancy evaluation in an office environment

1. 1. The objective of this paper is to investigate the indoor environment from the viewpoint of interaction between physical environment and the human responses. The field survey has been conducted over 1 year.

2. 2. A continuous measurement has been carried out for 1 week and distribution of variables have been measured for 1 day.

3. 3. The attitude of workers was investigated by a questionnaire.

4. 4. As the result, average luminance represented more than 1000 lx in the new building, in contrast with less tha 300 lx in the existing building.

5. 5. There was a significant difference of the occupants' response to the light environment between the two buildings.

6. 6. Measured thermal conditions are on the edge of the ASHRAE comfort envelope in summer, and in the neighborhood of the lower dry limit of the envelope in spring.

7. 7. The occupants' evaluations were remarkably changed before and after the moving. The office environment is better than that of the factory.

Apparent gene conversion in an Escherichia coli rec+ strain is explained by multiple rounds of reciprocal crossing-over

Summary Gene conversion, the non-reciprocal transfer of sequence information between homologous DNA sequences, has been reported in lower eukaryotes, mammals and in Escherichia coli. In an E. coli rec ⁺ strain, we established a plasmid carrying two different deleted neo genes (neoDL and neoDR) in an inverted orientation and then selected for homologous recombination events that had reconstructed an intact neo ⁺ gene. We found some plasmids that had apparently experienced intramolecular gene conversion. Further evidence, however, suggests that they are products of multiple rounds of reciprocal crossing-over,apparently involving two plasmid molecules. First, most of the Neo⁺ clones contained multiple types of Neo⁺ plasmids, although the frequency of producing the neo ⁺ clones was low. Second, all the neo ⁺ clones also contained, as a minority, one particular form of dimer, which can be formed by reciprocal crossing-over between neoDL of one plasmid molecule and neoDR of another plasmid molecule. Third, in reconstruction experiments, we cloned and purified this dimer and transferred it back into the rec ⁺ cells. The dimer gave rise to clones containing multiple types of neo ⁺ recombinant monomers, including those apparent gene conversion types, and containing only few molecules of this dimer plasmid.     

Genomic imprinting and evolution of insect societies

Reproductive division of labor is a hallmark of social insect societies where individuals follow different developmental pathways resulting in distinct morphological castes. There has been a long controversy over the factors determining caste fate of individuals in social insects. Increasing evidence in the last two decades for heritable influences on division of labor put an end to the assumption that social insect broods are fully totipotent and environmental factors alone determine castes. Nevertheless, the genes that underlie hereditary effects on division of labor have not been identified in any social insects. Studies investigating the hereditary effects on caste determination might have overlooked non-genetic inheritance, while transmission to offspring of factors other than DNA sequences including epigenetic states can also affect offspring phenotype. Genomic imprinting is one of the most informative paradigms for understanding the consequences of interactions between the genome and the epigenome. Recent studies of genomic imprinting show that genes can be differentially marked in egg and sperm and inheritance of these epigenetic marks cause genes to be expressed in a parental-origin-specific manner in the offspring. By reviewing both the eusocial Hymenoptera and termites, I highlight the current theoretical and empirical evidence for genomic imprinting in eusocial insects and discuss how genomic imprinting acts in caste determination and social behavior and challenges for future studies. I also introduce the new idea that genomic imprinting plays an essential role in the origin of eusociality.     

Comparison of neuronal responses in primate inferior-temporal cortex and feed-forward deep neural network model with regard to information processing of faces

Journal of Computational Neuroscience - Feed-forward deep neural networks have better performance in object categorization tasks than other models of computer vision. To understand the relationship...     

Preparation of optically active 4-chlorophenylalanine from its racemate by deracemization technique using transformant Escherichia coli cells

We have developed a method for the preparation of l-4-chlorophenylalanine from its racemate with Escherichia coli cells expressing a single foreign gene. l-4-Chlorophenylalanine was obtained in a high optical yield by the inversion of configuration of its d-form via the tandem reactions catalyzed by d-amino acid dehydrogenase (DadA) and branched-chain amino acid aminotransferase (BCAAT). While we constructed a plasmid for BCAAT utilizing the gene from Sinorhizobium meliloti ATCC 51124, the first enzyme DadA was the dadA-gene product from E. coli host cell itself, which was activated by the addition of l-alanine in the growth medium.