Trophodynamic structure of a swampy bog at the climax stage of limnological succession II. Bacterioplankton dynamics

Matsumi-ike Bog is a swampy bog that has attained the climax stage of limnological succession. The dynamics of bacterioplankton were studied in relation to the influence of environment factors. The water temperature was shown primarily affect bacterial dynamics as a limiting factor throughout the year. The second most profound factor on the dynamics was the concentration of dissolved organic carbon (DOC) when dead phytoplankton were the major DOC source in the bog, whereas phosphate concentration was most important in the periods when the dead emergent plants were responsible for the DOC supply.     

Embryo implantation is blocked by intraperitoneal injection with anti-LIF antibody in mice

Leukemia inhibitory factor (LIF) is essential for embryo implantation in mice and plays an important role in other mammals including humans. Intraperitoneal (i.p.) injections with anti-LIF antibody (7.5 μg/g body weight, 3 times) between D3 (D1 = day of vaginal plug detection) and D4 effectively blocked embryo implantation; complete inhibition was achieved in C57BL/6J mice, and implantation was dramatically reduced in ICR mice (reduced to 27%). Normal rabbit IgG used as the control did not disturb embryo implantation. Anti-LIF antibody was localized not only in the stroma, but also in the luminal epithelium and the glandular lumen after i.p. injections. Growth-arrested blastocysts were recovered from the uterus without any implantation sites in both strains. Blastocysts made contact with the LE on the antimesometrial side; however, uterine stromal cells did not undergo secondary decidual reaction, and the uterine lumen was open, even at D7. Several regions of decidualization in ICR mice treated with anti-LIF antibody were smaller than those of the control, and development of blastocysts was delayed. The expression of LIF-regulated genes, such as immune-responsive gene-1 and insulin-like growth factor binding protein-3, was significantly decreased in C57BL/6J mice treated with anti-LIF antibody compared with the control, but not in ICR mice. The present study demonstrated that simple ip injections of an antibody are sufficient to block one of the important factors involved in embryo implantation in mice, and this method should also be easily applicable to the investigation of other factors involved in implantation.     

Differentiation of uterine natural killer cells in pregnant SCID (scid/scid) mice

To determine whether functional T- and B-cells can affect differentiation and/or proliferation of uterine natural killer (uNK) cells, their numbers in SCID mice (genotype, C.B.-17/Icr-scid/scid) were compared with those of control mice (genotype, C.B.-17/Icr-+/+) on days 8, 12 and 16 of pregnancy. Using biotinylated-Dolichos biflorus agglutinin (DBA) lectin staining, uNK cells can be readily classified into 4 subtypes, I to IV, from immature to mature types. The number of uNK cells was significantly lower in the decidua basalis of SCID mice than in that of control mice on day 8 of pregnancy. Particularly, the number of uNK cells of immature subtype II was significantly lower in SCID mice than in the control mice. By day 12, however, the uNK cell number in the SCID mice reached the same level as that of the control mice. It is likely that uNK cell differentiation in SCID mice was delayed during the early placentation period due to a lack of functional T and B cells.     

Soybean preference for Bradyrhizobium japonicum for nodulation

For the increase of the occupation ratio of inoculum strain in the competition with indigenous rhizobia, the relationship between Rj-genotypes of soybean and the preference of Rj-cultivars for various types of rhizobia for nodulation was investigated by using the Rj ₂ Rj ₄-genotype of soybean isolated from the cross between the Rj ₂ Rj ₃-cultivar IAC-2 and Rj ₄-one Hill (Ishizuka et al. 1993: Soil Sci. Plant Nutr., 39, 79-86). Firstly, these Rj ₂ Rj ₄-genotypes were found to harbor the Rj ₃-gene. The Rj ₂Rj₃Rj₄-genotypes of soybean were considered to exhibit a more narrow microsymbiont range for nodulation than the Rj ₂ Rj ₃-and Rj₄-cultivars. Therefore, rhizobia were isolated from the nodules of various Rj-genotypes of soybeans grown in soils, and the preference of the Rj ₂ Rj ₃ Rj ₄-genotype for indigenous rhizobia was examined. The nodule occupancy of serotype 110 was significantly higher in the bacteroids of the nodules from the Rj ₂ Rj ₃ Rj ₄-rgenotypes than in those from the other genotypes, non Rj-, Rj ₂ Rj _3-, and Rj ₄-cultivars. These results demonstrated that the Rj ₂ Rj ³ Rj ⁴-genotype prefers more actively serogroup USDA110 to the others of rhizobia. Thus, Rj ₂ Rj ₃ Rj ₄-genotype is superior to non- Rj-, Rj ₂ Rj ₃-, and Rj ₄-genotypes for the formation of efficient nodules for nitrogen fixation.     

Partial cloning of CYP2C23a genes and hepatic protein expression in eight representative avian species

Large interspecies differences in avian xenobiotic metabolism have been revealed by microsome‐based studies, but specific enzyme isoforms in different bird species have not yet been compared. We have previously shown that CYP2C23 genes are the most induced CYP isoforms in chicken liver. In this study, we collected partial CYP2C23a gene sequences from eight avian species (ostrich, blue‐eared pheasant, snowy owl, great‐horned owl, Chilean flamingo, peregrin falcon, Humboldt penguin, and black‐crowned night heron) selected to cover the whole avian lineage: Paleognathae, Galloanserae, and Neoaves. Genetic analysis showed that CYP2C23 genes of Galloanserae species (chicken and blue‐eared pheasant) had unique characteristics. We found some duplicated genes (CYP2C23a and CYP2C23b) and two missing amino acid residues in Galloanserae compared to the other two lineages. The genes have lower homology than in other avian lineages, which suggests Galloanserae‐specific rapid evolutionary changes. These genetic features suggested that the Galloanserae are not the most representative avian species, considering that the Neoaves comprise more than 95% of birds. Moreover, we succeeded in synthesizing an antipeptide polyclonal antibody against the region of CYP2C23 protein conserved in avians. However, comparative quantitation of CYP2C23 proteins in livers from six species showed that expression levels of these proteins differed no more than fourfold. Further study is needed to clarify the function of avian CYP2C23 proteins.     

Biobleaching of unbleached and oxygen-bleached hardwood kraft pulp by culture filtrate containing manganese peroxidase and lignin peroxidase fromPhanerochaete chrysosporium

Unbleached and oxygen-bleached hardwood kraft pulp (UKP and OKP), respectively, were bleached with a culture filtrate containing manganese peroxidase (MnP) and lignin peroxidase (LiP) fromPhanerochaete chrysosporium Burds. The brightness increases of UKP upon biobleaching with the culture filtrate with and without MnSO₄ were the same. The brightness increase of OKP with MnSO₄ decreased to about half that seen without MnSO₄. Changes in the brightness of UKP and OKP by treatment with the culture filtrate were determined. The brightness increased sharply by about eight points during the first 3h. The 3-h treatment was repeated seven times. The brightness increased linearly with the bleaching of UKP. On bleaching of OKP, the brightness increased slowly and stopped at about 78%.Part of this report was presented at the 62nd Pulp and Paper Research Conference of the Japan Tappi, Tokyo, June 1995     

Establishment of a LacZ marker rescue assay to detect infectious RD114 virus

Cats have an infectious endogenous retrovirus, named RD114 virus, and there is a possibility that RD114 virus has contaminated live attenuated vaccines, for which feline cells are used as a substrate. To monitor infectious RD114 virus in vaccines for cats, we developed a LacZ marker rescue assay to detect infectious RD114 virus. Among four human cell lines examined, TE671 cells (human rhabdomyosarcoma) were most susceptible to RD114 virus and supported RD114 replication efficiently. Infection was enhanced approximately 5 times by the addition of polybrene at concentrations of 2 to 8 microg/ml in the medium during viral adsorption. A 4-hr viral adsorption period was sufficient to obtain the maximum titer. By inoculating samples into TE671 cells transduced with the lacZ marker gene, the limiting diluted sample (i.e., less than 10 infectious units) was detected at 12 days post-inoculation by the LacZ marker rescue assay. Based on the results obtained in this study, we propose a standard protocol of the LacZ marker rescue assay to detect infectious RD114 virus.     

Analysis of acrylamide in a complex matrix of polyacrylamide solutions treated by heat and ultraviolet light

A recently developed headspace/solid-phase microextraction/gas chromatograph (GC) equipped with a nitrogen-phosphorus detector (NPD) (HS/SPME/GC/NPD) method was used to analyze acrylamide formed in an aqueous polyacrylamide solution (25%) treated by heat or photo-irradiation. Original polyacrylamide contained 0.43 +/- 0.11 microg/mL of acrylamide. When polyacrylamide solution was heated at 70 degrees C for 16 h with 0.5% potassium persulfate, the amount of acrylamide increased to 1.02 +/- 0.11 microg/mL. When polyacrylamide solution was irradiated by UV (lambda = 300 nm) for 16 h with 0.05% 2-anthraquinone sulfate sodium salt, the amount of acrylamide increased to 1.14 +/- 0.54 microg/mL. Polyacrylamide has been used in cosmetic formulations. The present study, therefore, suggests that there is another route of acrylamide exposure to humans in addition to foods and beverages.     

Spatial structures of N2O, CO2, and CH4 fluxes from Acacia mangium plantation soils during a relatively dry season in Indonesia

We investigated spatial structures of N₂O, CO₂, and CH₄ fluxes during a relatively dry season in an Acacia mangium plantation stand in Sumatra, Indonesia. The fluxes and soil properties were measured at 1-m intervals in a 1 × 30-m plot (62 grid points) and at 10-m intervals in a 40 × 100-m plot (55 grid points) at different topographical positions of the upper plateau, slope, and valley bottom in the plantation. Spatial structures of each gas flux and soil property were identified using geostatistical analysis. The means (±SD) of N₂O, CO₂, and CH₄ fluxes in the 10-m grids were 0.54 (±0.33) mg N m⁻² d⁻¹, 2.81 (±0.71) g C m⁻² d⁻¹, and −0.84 (±0.33) mg C m⁻² d⁻¹, respectively. This suggests that A. mangium soils function as a larger source of N₂O than natural forest soils in the adjacent province on Sumatra during the relatively dry season, while CO₂ and CH₄ emissions from the A. mangium soils were less than or consistent with those in the natural forest soils. Multiple spatial dependence of N₂O fluxes within 3.2 m (1-m grids) and 35.0 m (10-m grids), and CO₂ fluxes within 1.8 m (1-m grids) and over 65 m (10-m grids) was detected. From the relationship among N₂O and CO₂ gas fluxes, soil properties, and topographic elements, we suggest that the multiple spatial structures of N₂O and CO₂ fluxes are mainly associated with soil resources such as readily mineralizable carbon and nitrogen in a relatively dry season. The soil resource distributions were probably controlled by the meso- and microtopography. Meanwhile, CH₄ fluxes were spatially independent in the A. mangium soils, and the water-filled pore space appeared to mainly control the spatial distribution of these fluxes.