Approach to the Involvement of Influenza B Neuraminidase in the Cleavage of HA by Host Cell Protease Using Low pH-Induced Cell Fusion Reaction

ts7, a temperature-sensitive mutant defective in neuraminidase (NA) of influenza B/Kanagawa/73, lacks NA enzymatic activity at the nonpermissive temperature (37.5 C). When MDCK cells were infected with the mutant at the permissive temperature (32 C) and exposed to pH 5.2 medium, extensive cell fusion occurred. In contrast, at the nonpermissive temperature cells did not show cell fusion at all unless they were pretreated with trypsin, suggesting that at 37.5 C the hemagglutinin (HA) of ts7 is expressed at the cell surface in an uncleaved form. It was also found that the replacement of RNA segment 6 of ts7 with that of wild-type B/Lee resulted in the emergence of low pH-induced fusion activity as well as NA enzymatic activity at the incubation temperature of 37.5 C and that the addition of bacterial NA to the cultures infected with ts7 at 37.5 C early in infection brought about low pH-induced cell fusion. We suggest that the removal of neuraminic acid from the carbohydrate moiety of HA by NA is essential for the cleavage of HA by cellular protease.     

Cytotoxicity Induced by Monoclonal Antibody to α-Fetoprotein Coadministered with Spleen Cells of Nude Mice

This paper describes an attempt to effectively induce antibody-dependent cell-mediated cytotoxicity (ADCC) in nude mice. A monoclonal antibody against α-fetoprotein, 80G, coadministered with spleen cells from other nude mice bearing HuH-7N (xenograft of human hepatoma cell line, HuH-7) significantly suppressed the growth of HuH-7N as compared to treatment with 80G alone. 80G with spleen cells from normal nude mice also had some suppressive effect. In contrast, no effect was observed with each spleen cells alone as well as 80G alone. These results suggest that further supply of effector cells could enhance ADCC activity in nude mice.     

Elevated serum α-fetoprotein level of nude mice bearing hepatoma cells by treatment with monoclonal antibodies to α-fetoprotein

This study was carried out to clarify the reason for elevation of serum α-fetoprotein (AFP) level of nude mice bearing hepatoma cells after treatment with monoclonal antibodies (MoAbs) to AFP. MoAbs to AFP showed no effect on the cumulative amounts of AFP secreted from human hepatoma cell line, HuH-7, in vitro. However, the treatment of nude mice bearing HuH-7N cells (HuH-7 xenograft) with MoAbs to AFP led to elevation of the serum AFP level in spite of the fact that the growth curve of HuH-7N cells was similar to that for PBS treatment. This apparent elevation of the serum AFP level is thought to be due to the slow elimination of AFP-MoAb immune complexes with little lattice structure from circulation, but not the enhancement of AFP secretion of HuH-7N cells. Thus, when using a MoAb alone or MoAb-drug conjugate, the serum AFP level should only be cautiously used as a tumor marker for evaluating the targeting immunotherapy.     

Isolation and characterization of pock-forming plasmids for Streptomyces griseus from soil actinomycetes

Thirty independent actinomycetes strains carrying plasmids were isolated from soil. These plasmids were purified as cccDNA by CsCl-EtBr equilibrium density-gradient centrifugation. Plasmids that induce "pocks", namely formation of circular zones of sporulation-inhibition, were selected by protoplast transformation of streptomycin-producing strain, Streptomyces griseus ATCC10137. Six pock-forming plasmids, pOA7, pOA11, pOA15, pOA23, pOA29 and pOA30, were obtained, and their cleavage maps, transformation frequencies, and copy numbers, as well as their stability, are described.     

Hernandulcin in hairy root cultures of Lippia dulcis

The hairy root culture of Lippia dulcis Trev., Verbenaceae, was established by transformation with Agrobacterium rhizogenes A4. The transformed roots grew well in Murashige and Skoog medium containing 2% sucrose. The roots turned light green when they were cultured under 16 h/day light. The green hairy roots produced the sweet sesquiterpene hernandulcin (ca. 0.25 mg/g dry wt) together with 20 other mono- and sesquiterpenes, while no terpenes were detected in the nontransformed root cultures. The growth and hernandulcin production in the hairy root cultures were influenced by the addition of auxins to the medium. The addition of a low concentration of chitosan (0.2 – 10.0 mg / l) enhanced the production of hernandulcin 5-fold.Abbreviations Cht chitosan - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - MS Murashige and Skoog(1962)     

Immunochemical Studies on Bacterial Blood Group Substances

Blood group H-active polysaccharide has been prepared from “smooth” strain Escherichia coli 2B-V by Freeman's method. a-Fucosidase derived from Bacillus fulminans caused the liberation of fucose from this polysaccharide, together with concomitant loss of blood group H activity. The results of quantitative microanalysis, borohydride reduction, the Morgan-Elson reaction and enzymic hydrolysis with β-galactosidase using isolated oligosaccharides obtained by partial acid hydrolysis indicated that the O-specific side chain of the polysaccharide has a pentasaccharide unit which is β-d-Gal-(1→3)-d-GalNAc-(1→3)-d-GalNAc-Fuc with a D -glucose residue bound at some undetermined point on this structure. It was considered that terminal non-reducing fucose of the polysaccharide was liberated by partial acid hydrolysis.     

Manganese and Arsenic Oxidation Performance of Bacterium-Yunotaki 86 (BY86) from Hokkaido,Japan, and the Bacterium's Phylogeny

We examined the Mn(II) oxidation performance of a bacterium, BY86, collected at Yunotaki Falls Hokkaido, Japan. The bacterium showed rapid oxidation of Mn(II), and brown precipitates containing Mn formed within a few days of incubation. The presence of higher oxidation states of Mn than Mn(II) was ascertained by the UV-vis and XANES sutdy. This bacterium did not oxidize As(III) to As(V) in the absence of Mn. In the presence of Mn, however, As(III) was rapidly oxidized to As(V) on the cell surfaces. These findings indicate that BY86 does not have the ability to directly oxidize As(III) to As(V) within a short period of contact, but indirectly oxidizes it by the Mn oxides generated on the cell surfaces. A phylogenetical study disclosed that BY86 was most closely related to Bacillus cereus with an identity of 99.90%. It is expected that our findings in this study will contribute to the study of Mn(II)-oxidizing bacteria, which play an important role in the biogeochemical cycling of Mn as well as other trace elements including As.     

Genetic relationships of cichlid fishes from Lake Malawi based on mitochondrial DNA sequences

Limnology - The purpose of this study was to estimate the genetic distance, diversity and relationship of two large groups of Malawian cichlid, ‘mbuna’ living in rocky area and feeding...