The formulation of the control of an expression pattern in a gene network by propositional calculus

In this study we model a gene network as a continuous-time switching network. In this model, each gene has a binary state which indicates if the gene expresses or not. We propose a method to control a sequence of expression patterns in the gene network model by adding another continuous-time switching network. By using propositional calculus, we will show that the control problem can be formulated as a mixed-integer linear programming problem with linear constraints.     

Colominic acid inhibits the proliferation of cultured bovine aortic endothelial cells and injures their monolayers: cell density-dependent effects prevented by sulfation

Colominic acid (CA), produced by Escherichia coli K1, is a polymer of sialic acid linked through alpha (2-->8) glycosidic linkages. Although there are several studies on the biological activities of chemically sulfated CA, the activity of CA has been incompletely understood. In the present study, we investigated the effects of CA, prepared as an alpha2,8-linked homopolymer of N-acetylneuraminic acid, on the proliferation and monolayer maintenance of bovine aortic endothelial cells in culture. The results indicate that CA potently inhibits the proliferation of sparse endothelial cells without nonspecific cell damage. The inhibitory effect of CA was markedly stronger than those of sodium spirulan and calcium spirulan, known polysaccharides that inhibit endothelial cell proliferation. On the other hand, in dense endothelial cells, CA induced nonspecific cell damage and markedly injured the monolayer. These results indicate that CA has two distinct effects on vascular endothelial cells: one is the inhibition of proliferation when the cell density is low, and the other is the nonspecific cytotoxicity when the cell density is high. Interestingly, these cell density-dependent effects of CA could be prevented by sulfation of the CA chains. Therefore, it is concluded that CA not only inhibits the proliferation of sparse endothelial cells without nonspecific cell damage but also injures dense cells in a monolayer by nonspecific cytotoxicity, which can be prevented by sulfation of the polysaccharide.     

Occurrence ofHebeloma vinosophyllum on the forest ground after decomposition of crow carcass

Hebeloma vinosophyllum (Basidiomycota, Agaricales), a member of the ammonia fungi, occurred on the ground in the close vicinity of the decomposed carcass of a jungle crow,Corvus macrorhynchos, in a forest dominated byQuercus spp. in Urawa, Saitama Pref., central Japan. This is the first report of an ammonia fungus occurring at the site of a decomposed wild bird carcass.     

Cryobiological properties of immature zebrafish oocytes assessed by their ability to be fertilized and develop into hatching embryos

As a step to develop a cryopreservation method for zebrafish oocytes, we investigated the cryobiological properties of immature oocytes at stage III by examining their ability to mature and to develop into hatching embryos after fertilization. When oocytes were chilled at −5 °C for 30 min, the maturation rate decreased, but the rates of fertilization and hatching were not significantly different from those of controls. When oocytes were exposed to hypotonic solutions for 60 min at 25 °C, the rates of maturation, fertilization, and hatching decreased in a solution with 0.16 Osm/kg or below. When oocytes were exposed to hypertonic solutions (containing sucrose) at 25 °C for 30 min, the maturation rate decreased in solution with 0.51 Osm/kg, whereas the hatching rate decreased with lower osmolality (0.40 Osm/kg). In an experiment on the toxicity of cryoprotectants (∼10%, at 25 °C), it was found that glycerol and ethylene glycol were toxic both by the assessment of maturation and hatching. Propylene glycol, DMSO and methanol were less toxic by the assessment of maturation, but were found to be toxic by the assessment of hatching. Methanol was the least toxic, but it was less effective to make a solution vitrify than propylene glycol. Therefore, a portion of methanol was replaced with propylene glycol. The replacement increased the toxicity, but could be effective to reduce chilling injury at −5 °C. These results clarified the sensitivity of immature oocytes to various cryobiological properties accurately, which will be useful for realizing cryopreservation of zebrafish oocytes.     

Functional and Phenotypical Analysis of Subsets of Rat CD4+ T Cells

Rat CD4⁺ T cells were divided into two distinct subsets by a monoclonal antibody RTH-1 recognizing a unique epitope on rat CD45R. Cellular distribution of OX-22- and RTH-1-defined antigens was the same. However, OX-22 and RTH-1 recognized different epitopes that exist on rat CD45R. The expression of IL-4 gene was detected only in RTH-1^low CD4+ T cell subset upon various stimulations. In contrast, the expression of IL-2 and IFN-γ gene varied depending upon the nature of stimuli. The increased cell surface expression of CD44 was detected in RTH-1^high CD4+ T cell subset. Conversely the increased expression of CD2 was detected in RTH-1^low CD4+ T cell subset. The expression of CD3 and LFA-1 was not significantly different between RTH-1^high and RTH-1^low subsets.     

Cloning and nucleotide sequence of the gene braB coding for the sodium-coupled branched-chain amino acid carrier in Pseudomonas aeruginosa PAO

Summary The gene braB, encoding the Na^–-coupled carrier for branched-chain amino acids in Pseudomonas aeruginosa PAO, was cloned on cosmid pMMB34. The cosmid clones carrying the braB gene were identified as those that restored growth at low leucine concentration and Na^–-dependent leucine transport activity to P. aeruginosa PAO3536 defective in the transport of branched-chain amino acids. Determination of the nucleotide sequence of the DNA fragment shows that the braB gene comprises 1311 bp and encodes a hydrophobic protein of 437 amino acids with a calculated M_r of 45279. The hydropathy profile suggests that there exist in the carrier protein 12 hydrophobic segments long enough to traverse the membrane. The amino acid sequence shows a high degree of homology with thebrnQ product, a branched-chain amino acid carrier of Salmonella typhimurium, while no homology in the nucleotide sequences is found in the braB and brnQ genes.     

Detection of 1-phenyl-N-methyl-1,2,3,4-tetrahydroisoquinoline and 1-phenyl-1,2,3,4-tetrahydroisoquinoline in human brain by gas chromatography—tandem mass spectrometry

1-Phenyl-N-methyl-1,2,3,4-tetrahydroisoquinoline and 1-phenyl-1,2,3,4-tetrahydroisoquinoline were detected for the first time in parkinsonian human brain using gas chromatography-tandem mass spectrometry (GC-MS-MS). Since these compounds are structural analogues of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that produces parkinsonism in humans, they might be candidates for endogenous MPTP-like neurotoxins.