Theoretical study of the electronic structure and conformation of polysilole and its derivatives

The electronic structures and conformations in the optimized geometries of polysilole and its derivatives are studied theoretically, using the one-dimensional tight-binding self-consistent field crystal orbital (SCF-CO) method. It has been found that the copolymer formed by alternating aromatic silole and quinoid thiophene has a relatively small bandgap value. We observe that polysilole may show an interesting thermochromic behavior, because the conformation of polysilole is considerably easier to change at lower temperature than that of polythiophene.     

Electronic structure of siloxene model compounds

The electronic structures of one-dimensional and two-dimensional siloxene (Si₆O₃H₆) model compounds have been examined theoretically, using the semiempirical tight-binding self-consistent field crystal orbital (SCF-CO) method. These compounds are formed by silicon-based chain and planar structures containing a regular array of oxygen atoms. Results show that the two-dimensional polysilane in which OH groups are substituted for H atoms possesses a relatively smaller direct gap than other siloxenes. It is assumed that the electronic structures of siloxenes are affected not only by the dimensionality of Si-Si -conjugational networks due to an array of oxygen atoms, but also by the diminishing of the electron population in the Si-Si bonding orbitals caused by oxygen atoms with large electronegativity.     

Induction of {alpha}-Amylase is Repressed by Uniconazole, an Inhibitor of the Biosynthesis of Gibberellin, in a Dwarf Mutant of Rice, Waito-C

A system for induction of synthesis of     

Expression in Yeast of a Fusion Gene Composed of the Promoter of a Heat-Shock Gene from Arabidopsis and a Bacterial Gene for {beta}-Glucuronidase

Production of a functional ß-glucuronidase (GUS) proteinwas induced by exposure of exponentially growing yeast cellsto heat shock after transformation of the GUS gene under thecontrol of the promoter of the heat-shock gene, HSP18.2, fromArabidopsis. Yeast cyr and bcy mutations appeared to have essentiallyno effect. ¹Present Address: Laboratory of Plant Molecular Biology, TheRockefeller University, 1230 York Avenue, New York, NY 10021-6399,U.S.A.     

Cloning of the blasticidin S deaminase gene (BSD) from Aspergillus terreus and its use as a selectable marker for Schizosaccharomyces pombe and Pyricularia oryzae

Aspergillus terreus produces a unique enzyme, blasticidin S deaminase, which catalyzes the deamination of blasticidin S (BS), and in consequence confers high resistance to the antibiotic. A cDNA clone derived from the structural gene for BS deaminase (BSD) was isolated by transforming Escherichia coli with an Aspergillus cDNA expression library and directly selecting for the ability to grow in the presence of the antibiotic. The complete nucleotide sequene of BSD was determined and proved to contain an open reading frame of 393 bp, encoding a polypeptide of 130 amino acids. Comparison of its nulceotide sequence with that of bsr, the BS deaminase gene isolated from Bacillus cereus, indicated no homology and a large difference in codon usage. The activity of BSD expressed in E. coli was easily quantified by an assay based on spectrophotometric recording. The BSD gene was placed in a shuttle vector for Schizosaccharomyces pombe, downstream of the SV40 early region promoter, and this allowed direct selection with BS at high frequency, following transformation into the yeast. The BSD gene was also employed as a selectable marker for Pyricularia oryzae, which could not be transformed to BS resistance by bsr. These results promise that the BSD gene will be useful as a new dominant selectable marker for eukaryotes.     

Retrotransposon-induced ectopic expression of the Om(2D) gene causes the eye-specific Om(M) phenotype in Drosophila ananassae

Optic morphology (Om) mutations in Drosophila ananassae map to at least 22 loci, which are scattered throughout the genome. Om mutations are all semidominant, neomorphic, nonpleiotropic, and associated with the insertion of a retrotransposon, tom. We have found that the Om(2D) gene encodes a novel protein containing histidine/proline repeats, and is ubiquitously expressed during embryogenesis. The Om(2D) RNA is not detected in wild-type eye imaginal discs, but is abundantly found in the center of the eye discs of Om(2D) mutants, where excessive cell death occurs. D. melanogaster flies transformed with the Om(2D) cDNA under control of the hsp70 promoter display abnormal eye morphology when heat-shocked at the third larval instar stage. These results suggest that the Om(2D) gene is not normally expressed in the eye imaginal discs, but its ectopic expression, induced by the tom element, in the eye disc of third instar larvae results in defects in adult eye morphology.     

Stimulatory effect of β-alanyl-L-histidinato zinc on cell proliferation is dependent on protein synthesis in osteoblastic MC3T3-E1 cells

The effect of -alanyl-L-histidinato zinc (AHZ) on bone metabolism was investigated in osteoblastic MC3T3-El cells. Cells were cultured for 3 days at 37°C in a CO₂ incubator in plastic dishes containing -modified minimum essential medium supplemented with 10% fetal bovine serum. After the cultures, the medium was exchanged for that containing 0.1% bovine serum albumin plus various concentrations of AHZ or other reagents, and the cells were cultured further for appropriate periods of time. The presence of AHZ (10^–7–10^–5M) stimulated the proliferation of cells. AHZ (10^–6 and 10^–5M) increased deoxyribonucleic acid (DNA) content in the cells with 48hr-culture. This increase was completely blocked by the presence of cycloheximide (10^–6M) or hydroxyurea (10^–3M). Also, the presence of cycloheximide (10^–6M) completely inhibited the AHZ (10^–5M)-induced increase in the proliferation of cells. Meanwhile, parathyroid hormone (10^–7M), estrogen (10^–9M) and insulin (10^–M) significantly increased cellular DNA content. However, these hormonal effects clearly lowered in comparison with that of AHZ (10^–5M). Dibutyryl cyclic AMP (10^–4M) and zinc sulfate (10^–5M) did not cause a significant increase in cellular DNA content. The present results support the view that AHZ has a direct specific proliferative effect on osteoblastic cellsin vitro and that this effect is dependent on protein synthesis.     

Establishing a new genus,Chiharadinium gen. nov. (Peridiniales,Dinophyceae) for a tidal pool dinoflagellate formerly known as Scrippsiella hexapraecingula

To determine its accurate taxonomic position, a tidal pool bloom-forming dinoflagellate, Scrippsiella hexapraecingula was re-investigated using light, scanning and transmission electron microscopy together with a phylogenetic analysis based on concatenated ribosomal DNA sequences. The culture strains used in this study were established from intertidal rock pool samples taken from Jogashima, Kanagawa prefecture and Heisaura, Chiba prefecture, Japan and were identified as S. hexapraecingula originally described by Horiguchi and Chihara from a tidal pool in Hachijo Island, Tokyo, Japan in 1983. The thecal plate arrangement was determined as Po, X, 4′, 3a, 6″, 6c, 5s, 5″′, 2″″. The internal structure was investigated for the first time. The organism has typical dinoflagellate cellular organelles such as a dinokaryotic nucleus, mitochondria with tubular cristae, trichocysts and pusule. The chloroplast was single and connected to the central pyrenoid (stalked type). The eyespot found in the sulcus is of the B type with two rows of superficial intraplastidal lipid globules directly overlain by an extraplastidal single layer of crystalline bricks enveloped by a common membrane. The apical pore is plugged by a double-layered stub-like structure. Stalk building material for attachment covered the apical pore. Phylogenetic analysis indicated that S. hexapraecingula was most closely related to a freshwater dinoflagellate, Peridiniopsis borgei, the type species of the genus Peridiniopsis. However, clear differences exist between these two organisms, including their thecal plate arrangement, habitat and habit. As a result, a new genus, Chiharadinium Dawut & T. Horiguchi gen. nov. has been proposed rather than attempting to accommodate S. hexapraecingula in the genus Peridiniopsis. The new combination, Chiharadinium hexapraecingulum (T. Horiguchi & Chihara) Dawut & T. Horiguchi comb. nov. has been proposed.     

Correction to: Comparison of the usability of an automatic sleep staging program via portable 1-channel electroencephalograph and manual sleep staging with traditional polysomnography

Sleep and Biological Rhythms -