Screening for microorganisms with specific characteristics by flow cytometry and single-cell sorting

Flow cytometry used in combination with single-cell sorting is a powerful technique for the identification and isolation of microbial cells with particular characteristics, especially when such cells grow more slowly than other cells in a large heterogeneous population. Many applications of flow cytometry with cell sorting, originally used by specialists studying mammalian cells, have been modified so that microorganisms also can be evaluated. The methods can now be used more widely because of the increasing availability of the expensive equipment. There are means for the fluorescence detection of a wide variety of properties, such as amounts of various cell components, specific sequences of peptides and nucleotides, cell functions, and enzyme activities. From the extensive literature, representative reports of an assortment of uses of flow cytometry with cell sorting are reviewed in this article, intended to introduce the technique and its many advantages to microbiologists.     

Molecular Design, Characterization, and Application of Multiinformation Dyes (MIDs) for Optical Chemical Sensings. 3. Application of MIDs for λ(max)-Tunable Ion-Selective Optodes

By utilizing "multiinformation dyes (MIDs)", which have plural spectral change characteristics such as an absorption maximum wavelength (λ(max)) shift based on a polarity change and an absorbance change due to protonation, novel λ(max)-tunable ion-selective optodes were proposed and prepared by employing MIDs with membrane solvents having different polarities. For controlling the detecting λ(max) of the optode, the novel polar membrane solvent [2-[[6-(2-nitrophenoxy)hexyl]oxy]methyl]isobutane-1,3-diol was designed and synthesized, which was used together with a typical membrane solvent nitrophenyl octyl ether. By mixing these two membrane solvents, the λ(max) position of the optode detection wavelength can be shifted and controlled and was successfully applied to a λ(max)-tunable Li(+)-selective optode based on a highly Li(+)-selective ionophore TTD14C4. The λ(max) tuning technique is useful for preparing an optode system using a low-cost light source such as a light-emitting diode or a popular laser.     

Photoautotrophic cultures of the host and transformed cells of Marchantia polymorpha under controlled incident light intensity

Photoautotrophic cultures of the host and transformed cells of the liverwort, Marchantia polymorpha, were examined. In cultures in flat glass flasks under various light intensities, it was found that the growth rates of both the cells increased with increase in light intensity in the range of 0 to 25 W/m2, but further increase in light intensity caused photoinhibition of the growth of the cells. Cultures of both the types of cells under light-controlled conditions using an externally illuminated bioreactor were carried out taking into consideration the inhibition of cell growth by excessive light and the light intensity distributions in the cell suspensions. In these cultures, 2.1 (transformed cells) and 3.3 (host cells) kg dry cell weight per m3 were harvested at culture times of 9.0 and 10 d, respectively. These values were larger than those obtained in cultures of the respective cells at a fixed incident light intensity of 25 W/m2.     

Gene therapy for hematological malignancies

The management of avascular necrosis of the capitellum of the adolescent elbow continues to be a dilemma. This article is a critical retrospective analysis of 12 pediatric patients (mean age at surgery 14.5 years) who underwent arthroscopic debridement alone followed by early range of motion. Follow-up at a mean of 3.2 years (range, 2.0 to 5.7 years) indicated that the average flexion contracture improved from 23 degrees preoperatively to 10 degrees postoperatively. All patients had remodeling of the capitellum by plain radiographs; however, five patients had associated enlargement of the radial head. Eleven patients had minimal mechanical symptoms after the procedure and were highly satisfied. One patient had substantial enlargement of the radial head with continued loss of supination and mechanical symptoms requiring radial head resection 2 years after the index procedure. Five patients had a triangular avulsion fragment present off the lateral capsule. A statistically significant worse subjective outcome was associated with the presence of this fragment (P < .005). There were no complications.     

Human buprenorphine N-dealkylation is catalyzed by cytochrome P450 3A4

Buprenorphine (BN) is a thebaine derivative with analgesic properties. To identify and characterize the cytochrome P450 (CYP) enzyme(s) involved in BN N-dealkylation, in vitro studies using human liver microsomes and recombinant human CYP enzymes were performed. Norbuprenorphine formation from BN was measured by a simple HPLC-UV assay method, without extraction. The BN N-dealkylation activities in 10 human liver microsomal preparations were strongly correlated with microsomal CYP3A-specific metabolic reactions, i.e. triazolam 1'-hydroxylation (r = 0.954), midazolam 1'-hydroxylation (r = 0.928), and testosterone 6beta-hydroxylation (r = 0.897). Among the eight recombinant CYP enzymes studied (CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4), only CYP3A4 could catalyze BN N-dealkylation. The apparent KM value for recombinant CYP3A4 was similar to that for human liver microsomes (23.7 vs. 39.3 +/- 9.2 microM). The demonstration of BN N-dealkylation by recombinant CYP3A4 and the agreement in the affinities (apparent KM values) of human liver microsomes and recombinant CYP3A4 provide the most supportive evidence for BN N-dealkylation being catalyzed by CYP3A4.     

New electro-optical effect: optical activity of electric-field-induced twisted-nematic liquid crystal

A new electro-optical effect in nematic or nematic-cholesteric mixed liquid crystals is described which allows a 90° polarisation plane rotation of linearly polarised incident light induced by the electric field.     

Mutations in the large subunit of U2AF disrupt pre-mRNA splicing, cell cycle progression and nuclear structure

The prp2 gene of fission yeast has previously been shown to encode the large subunit of the splicing factor spU2AF. SpU2AF(59) is an evolutionarily conserved protein that has an arginine/serine-rich region and three RNA recognition motifs (RRMs). We have sequenced three temperature-sensitive alleles of prp2 and determined that the mutations result in single amino acid changes within one of the RRMs or between RRMs. All mutant alleles of prp2 have pre-mRNA splicing defects at the non-permissive temperature. Although the mutant strains are growth-arrested at 37 degrees C, they do not elongate like typical fission yeast cell cycle mutants. The DNA of the prp2(-) strains stains more intensely than a wild-type strain, suggesting that the chromatin may be condensed. Ultrastructural studies show differences in the mutant nuclei including a prominent distinction between the chromatin- and non-chromatin-enriched regions compared to the more homogenous wild-type nucleus. Two-hybrid assays indicate that some of the wild-type protein interactions are altered in the mutant strains. These results suggest that normal functioning of spU2AF(59) may be essential not only for pre-mRNA splicing but also for the maintenance of proper nuclear structure and normal cell cycle progression.     

Microanalyses on the RuO2 Particle–Glass Matrix Interface in Thick-Film Resistors with Piezoresistive Effects

The piezoresistive mechanisms of composite thick films based on RuO₂ particles and both calcium-borosilicate and bismuth-borosilicate glass matrices were investigated by chemical and electrical microanalyses. The resistor based on bismuth-borosilicate glass showed higher sensitivity than that based on calcium-borosilicate glass. It was confirmed that the diffusion of ruthenium into glass affects the binding state of RuO₂ at the interface of the glass. Furthermore, an intermediate resistive layer is detected around the RuO₂ particle. These results suggest that the piezoresistive effect is related to a change in the electrical conductivity of the interfacial reaction layer caused by the diffusion of ruthenium into glass.     

Photoconductive terahertz transceiver

A photoconductive dipole antenna can be used as a transceiver, which alternately transmits pulsed electromagnetic radiation and receives the return signal. Preliminary results of using a photoconductive terahertz transceiver with femtosecond optics are reported