Cancer Cell Analyses at the Single Cell-Level Using Electroactive Microwell Array Device

Circulating tumor cells (CTCs), shed from primary tumors and disseminated into peripheral blood, are playing a major role in metastasis. Even after isolation of CTCs from blood, the target cells are mixed with a population of other cell types. Here, we propose a new method for analyses of cell mixture at the single-cell level using a microfluidic device that contains arrayed electroactive microwells. Dielectrophoretic (DEP) force, induced by the electrodes patterned on the bottom surface of the microwells, allows efficient trapping and stable positioning of single cells for high-throughput biochemical analyses. We demonstrated that various on-chip analyses including immunostaining, viability/apoptosis assay and fluorescent in situ hybridization (FISH) at the single-cell level could be conducted just by applying specific reagents for each assay. Our simple method should greatly help discrimination and analysis of rare cancer cells among a population of blood cells.     

Seasonal succession of a microphagotroph community in a small pond during litter decomposition

Temporal dynamics of a lentic microphagotroph community were studied during leaf litter decomposition from December to May. Small plastic vessels containing leaf litter were placed on a pond bottom. They were sampled periodically to collect microphagotrophs. Three abiotic factors and abundance of two food items were also measured to analyze the autogenic and allogenic phenomena during a microphagotroph succession. Three behavior types were recognized in dominant taxa: a free-swimming type, a vagile (creeps on substratum, sometimes swims) type, and a voluntarily fixed type. Dominant taxa changed from the free-swimming to the vagile type up to mid-March, and the reverse change occurred from mid-April. Principal component analysis (PCA) indicated four factors affecting the dynamics of the community: water temperature as a seasonal factor, detritus volume on the litter surface as a habitat factor, and densities of bacteria and small flagellates as food factors. Taxa replacement appeared to occur through two mechanisms. (1) Dominance of small holotrichs, a free-swimming type, was brought about by a high bacterial density caused by seasonal events, i.e., leaf fall in December and detritus formation by litter feeders in mid-April. This is an allogenic aspect of community dynamics. (2) The free-swimming type was replaced by the vagile one during the period with high taxa diversity. This replacement occurred through intertaxa competition for scarce food and/or selective predation by larger microphagotrophs. It is an autogenic process within the community.     

Use of an activated carbon column for the synthesis of disaccharides by use of a reversed hydrolysis activity of β-galactosidase

Summary An activated carbon column was utilized for the synthesis of disaccharides by use of a reversed hydrolysis activity of an immobilized -galactosidase column in order to shift the equilibrium to the direction of condensation. The yields of lactulose and allo-lactulose from galactose and fructose, and N-acetyl lactosamine and N-acetyl allolactosamine from galactose and N-acetyl glucosamine, were 11.3% and 10.0%, respectively.     

Biology of mammary fat pad in fetal mouse: capacity to support development of various fetal epithelia in vivo

Epithelia from the lobular part of submandibular salivary gland, glandular stomach, intestine and colon of 14-day C3H/HeN fetuses, and from pituitary gland and pancreas of 12-day fetuses were recombined with 14-day mammary fat pad precursor tissue and syngrafted under the kidney capsule. The normal organogenetic development typical of the epithelium occurred. The same epithelia taken from earlier stage fetuses did not develop normally. Thus, 14-day fetal mouse mammary fat pad precursor tissue has the capacity to support normal organogenesis of various fetal epithelia of developmentally advanced stages. This supportive capacity is decreased in the fat pad precursor tissue of 17- to 18-day fetal mice and is entirely lost postnatally.     

Hydrophobicity of Fusobacterium necrophorum biovars A and B

Abstract Biovar A strains of Fusobacterium necrophorum exhibited high hydrophobicity when examined by the method of Rosenberg et al. Biovar B strains showed a lower cell surface hydrophobicity than biovar A strains. Biovar B strains were divided into 2 groups according to their hydrophobic activity. The strains of biovar A and the first group of biovar B were increasingly removed from aqueous phase to octane phase by increasing the volume of octane, but the turbidity of the second group of biovar B was not significantly affected. The hydrophobicity of biovar A strains decreased on heating at 60 and 100°C for 30 min.     

Cloning and expression of a novel rat GABAA receptor

Two full-length cDNA clones encoding alpha- and beta-subunits of a GABAA receptor have been isolated from a rat cerebral cortex cDNA library. The mature alpha-subunit protein consists of 428 amino acids with a calculated Mr of 48,680. This protein is highly homologous (approximately 99% amino acid identity) with the bovine brain alpha 1-subunit receptor [(1988) Nature 335, 76-79]. The mature rat beta-subunit receptor is a 448 amino acid polypeptide and shares approximately 80% amino acid identity with the previously characterized bovine GABAA receptor beta-subunit [(1987) Nature 328, 221-227]. Co-expression of the cloned DNA in Xenopus oocytes produces a functional receptor and ion channel with pharmacological characteristics of a GABAA receptor. GABAA alpha- and beta-subunit mRNA is detectable in the cortex, cerebellum and hippocampus.     

Surface Charge Density Estimation of Vigna mungo Protoplasts Using a Fluorescent Dye, 9-Aminoacridine

We showed that the surface charge density of protoplasts canbe estimated by the 9-aminoacridine method. The estimated surfacecharge density of the protoplasts isolated from elongating regionsof Vigna mungo root was – 39 ? 8 mC/m². The negative surfacecharge density increased when protoplasts were treated withglutaraldehyde or when EDTA was added to the protoplast suspensionmedium. These results support the validity of our estimationof the surface charge density of protoplasts by the 9-aminoacridinemethod. The concentration of amino groups at the surface ofthe protoplasts was estimated to be 34 mC/m². (Received June 19, 1987; Accepted April 11, 1988)