Identification and characterization of rhizobacteria isolated by enrichment culture on spinach roots

Rhizobacteria can be used for biological control and environmental restoration. In this study, we performed enrichment culture of rhizobacteria, identified isolates, and investigated the physiological properties of the bacterial isolates. Five bacteria differing in their colony morphology were isolated from spinach roots as enriched rhizobacteria. Four isolates were identified by sequencing of 16S rDNA as β and γ-Proteobacteria; 16S rDNA sequencing was not completed on one isolate. Based on microscopic observation, we determined that at least two types of bacteria differing in their morphology co-existed in this isolate, and that it may not be possible to culture the two types separately. Based on tests of substrate utilization, we could not find the characteristics that were common to the isolates. One of the five isolates was inoculated into non-sterile soil, and we examined its root-colonizing ability. The test strain which was not detected in the non-rhizosphere soil, accounted for about 20% of the total bacteria on the roots. These results suggested that enrichment culture might be useful for isolating bacteria with a high root-colonizing ability     

Nitrogen-fixing microorganisms in paddy soils (Part 2) distribution of blue-green algae in paddy soils and the relationship between the growth of them and soil properties

As was shown in the previous report^l), a close connection between the photosynthetic autotrophs and nitrogen fixation in paddy soils was demonstrated.     

Effects of oral glucosamine hydrochloride administration on plasma free amino acid concentrations in dogs

We examined the effects of oral glucosamine hydrochloride (GlcN), N-acetyl-D-glucosamine (GlcNAc) and d-glucose (Glc) administration on plasma total free amino acid (PFAA) concentrations in dogs. The PFAA concentrations increased in the control group and the GlcNAc group at one hour after feeding, and each amino acid concentration increased. On the other hand, in the GlcN group and the Glc group PFAA concentrations decreased at one hour after feeding. A significant decrease in amino acid concentration was observed for glutamate, glycine and alanine. Our results suggest the existence of differences in PFAA dynamics after oral administration of GlcN and GlcNAc in dogs.     

Determination of antigenic proteins of housedust mites in 90 dogs suffering from atopic dermatitis

Housedust mites, Dermatophagoides pteronyssinus (D. pteronyssinus) and Dermatophagoides farinae (D. farinae), are the important causative agents of allergic diseases in human and animals. By using 165 dogs suffering from atopic dermatitis (AD), serum levels of immunogloblin E (IgE) antibody against 25 kinds of allergen including housedust mites were determined. Housedust mites were the most frequent allergen against which 90 of the 165 allergic dogs (54.5%) by IMMUNODOT assay. With the further analysis of immunoblotting assay in the 90 dogs sensitized with housedust mites, antigenic proteins of housedust mites recognized by IgE antibodies were with the apparent molecular masses of 15, 76, 90, 98, and 170-kD. Among them, the 15-kD protein that might be identical to Group 2 antigens (Der f2, Der p2) was prominently observed (52/90). This study indicates that about a half of dogs with AD were sensitized to housedust mites, suggesting that Group 2 antigens of housedust mites may be a major allergen in canine AD.     

Establishment of ES cells from inbred strain mice by dual inhibition (2i)

A number of mouse ES cells from inbred strains have been established to date, but efficiency varies across the different strains. The 129 strain mouse is efficient to establish, whereas C57BL/6 and BALB/c strains are not. It is possible that their genetic backgrounds account for the difference in their ability to establish ES cell lines. In this study, we attempted to establish C57BL/6J and BALB/c Cr ES cells by dual inhibition (2i) using two inhibitors (PD0325901 and CHIR99021) of extracellular signal regulated-kinase (ERK) and glycogen synthase kinase-3 (GSK-3), which promote ES cell differentiation. The results revealed that the establishment efficiencies of C57BL/6J and BALB/c Cr ES cells were remarkably increased by 2i. These ES cells stably expressed pluripotent markers and generated high-contribution chimeras with germline transmission. Furthermore, we generated germline chimeras from C57BL/6J ES cells through the method of gene modification. These findings indicate that 2i is a powerful tool for establishing C57BL/6J and BALB/c Cr ES cells with the ability to generate germline chimeras.     

Modeling the spatially dynamic distribution of humans in the Oregon (USA) Coast Range

A common approach to land use change analyses in multidisciplinary landscape-level studies is to delineate discrete forest and non-forest or urban and non-urban land use categories to serve as inputs into sets of integrated sub-models describing socioeconomic and ecological processes. Such discrete land use categories, however, may be inappropriate when the socioeconomic and ecological processes under study are sensitive to a range of human habitation. In this paper, we characterize the spatial dynamic distribution of humans throughout the forest landscape of western Oregon (USA). We develop an empirical model describing the spatial distribution and rate of change in historic building densities as a function of a gravity index of development pressure, existing building densities, slope, elevation, and existing land use zoning. We use the empirical model to project changes in building densities that are applied to a 1995 base map of building density to describe future spatial distributions of buildings over time. The projected building density maps serve as inputs into a multidisciplinary landscape-level analysis of socioeconomic and ecological processes in Oregon's Coast Range Mountains. This revised version was published online in July 2006 with corrections to the Cover Date.     

Application of DGGE analysis to the study of bacterial community structure in plant roots and in nonrhizosphere soil

To analyze the structure of bacterial communities in spinach roots and in the nonrhizosphere soil, we used PeR-amplified 16S rRNA gene fragments separated by denaturing gradient gel electrophoresis (DGGE). DGGE revealed a large number of band patterns, which were ascribed to various bacterial species composing each of the bacterial communities. The pattern from the roots was less complex than that from the soil. It is considered that DGGE analysis is suitable for studies of bacterial community structure in soil-plant ecosystems.     

Effect of placental soluble factors on growth and differentiation of mouse ectoplacental cone in vitro.

The effect of soluble fractions derived from the placenta on the outgrowth and giant cell transformation of the ectoplacental cone (EPC) was investigated in vitro. EPCs taken from the fetal mice on day 7.5 post coitum (pc) were incubated with alpha-MEM-containing fetal calf serum (FCS) (FCS-alpha-MEM) for 24 hr. Then, the medium was exchanged with alpha-MEM alone, FCS-alpha-MEM, or alpha-MEM containing a crude extract from placental region on day 8.5, 10.5 or 12.5 pc (10 ml phosphate buffer/g placenta). Each EPC was continued to be incubated for 6 days, and the rate of EPC outgrowth and the number of trophoblastic giant cells (TGCs) were evaluated under a phase-contrast microscope. As a result, the administration of each placental extract significantly induced the cell spreading and TGC transformation of EPC as compared with the culture in alpha-MEM alone. The rate of cell-spreading rapidly increased on the 2nd day after incubation in the medium containing placental extracts. In particular, EPC outgrowth was more remarkable in the medium containing the 10.5-day placental extract than in the other media including FCS-containing medium. The number of transformed TGCs was also the largest in the 10.5-day medium among the groups examined. These results indicate that certain placental factors at mid-gestation, especially on day 10.5 pc, may facilitate the EPC differentiation.