Extracellular Accumulation of DNA by Hydrocarbon-utilizing Bacteria

Some hydrocarbon-utilizing bacteria grown on n-paraffin as the sole source of carbon accumulated extracellularly a considerable amount of DNA (0.1 g to 0.6 g per liter) which was free from intact cells and slime materials. This was particularly noted when the strains belonging to Pseudomonad were employed. n-Paraffin was a preferable carbon source for the accumulation of DNA by Pseudomonad, while a strain of Arthrobacter accumulated DNA by growing it on glucose.

The DNA thus accumulated was easily isolated and purified free from other cellular components. The purified DNA was highly polymerized (above 4 × l0⁶ daltons), having the same base composition as the cellular DNA.     

Production of a New Ammonucleoside, 9-(2′-Amino-2′-deoxypentofuranosyl) Guanine,by Aerobacter sp.

A species of Aerobacter KY 3071 isolated from soil was found to produce a guanosine analog. It was isolated in a crystalline form from the broth culture through chromatographies on ion-exchange resins and porous resin, and characterized as 9-(2′-amino-2′-deoxypentofuranosyl) guanine by paper chromatographies, UV, NMR, IR spectra and chemical analysis.

This compound inhibited the growth of E. coli KY 8323 but not of other bacteria including most of the other strains of E. coli. It also showed antitumor activity against HeLa cell and Sarcoma 180.     

Effect of organic rice farming on planthoppers 4. Reproduction of the white backed planthopper,Sogatella furcifera Horváth (Homoptera: Delphacidae)

The reproduction ofSogatella furcifera was investigated in a chemically fertilized rice field and an organically farmed field. In the latter, the density of immigrants was significantly higher, while the settling rate of female adults and the survival rate of immature stages of ensuing generations were lower. The number of eggs laid by a female of the invading and following generations was smaller, and the percentage of brachypterous females in the next generation was also lower. Consequently, the density of nymphs and adults in the ensuing generations decreased in the organically farmed field. For an experimental comparison, potted rice plants were cultivated using seedlings and soil from the chemically fertilized or the organically farmed fields. WhenSogatella furcifera was reared on these plants, both the reproductive rate and the appearance rate of brachypterous female adults were lower in the organic treatment. Egg hatchability was also lower in the organic treatment. This experiment suggested that a specific nutritional condition in rice plants suppressed the population ofS. furcifera in the organically farmed field.     

Microsomal Prostaglandin E Synthase Type 2 (mPGES2) Is a Glutathione-dependent Heme Protein,and Dithiothreitol Dissociates the Bound Heme to Produce Active Prostaglandin E2 Synthase in Vitro

An x-ray study indicated that microsomal prostaglandin E synthase type 2 (mPGES2) is a heme-bound protein and catalyzes prostaglandin (PG) H₂ degradation, but not PGE₂ formation (Yamada, T., and Takusagawa, F. (2007) Biochemistry 46, 8414–8424). In response to the x-ray study, Watanabe et al. claimed that mPGES2 is a heme-free protein and that both the heme-free and heme-bound proteins have PGE₂ synthesis activity in the presence of dithiothreitol (Watanabe, K., Ito, S., and Yamamoto, S. (2008) Biochem. Biophys. Res. Commun. 367, 782–786). To resolve the contradictory results, the heme-binding scheme of mPGES2 was further characterized in vivo and in vitro by absorption and fluorescence spectroscopies. A substantial amount of heme-bound mPGES2 was detected in cell extracts. The heme content in mPGES2 was increased along with an increase in Fe³⁺ in the culture medium. Heme-free mPGES2 was converted to the heme-bound form by mixing it with pig liver extract, indicating that mPGES2 is capable of forming a complex with heme in mammalian cells. Heme binds to mPGES2 only in the presence of glutathione. The newly determined heme dissociation constant (2.9 nm) supports strongly that mPGES2 is a heme-bound protein in vivo. The bound heme was not dissociated by oxidation by H₂O₂ or reduction by glutathione or 2-mercaptoethanol. However, reduction by dithiothreitol (an artificial reducing compound) induced the bound heme to dissociate from mPGES2 and released heme-free mPGES2, which exhibited PGE₂ synthesis activity in vitro. Imidazole bound to mPGES2 by stacking on the bound heme and inhibited heme oxidation by H₂O₂ and reduction by dithiothreitol.     

Egg size manipulation in the migrant skipper, Parnara guttata guttata (Lepidoptera: Hesperiidae), in response to different host plants

Female adults of the migrant skipper, Parnara guttata guttata, lay different-sized eggs on different host plants in different generations. Moreover, P. g. guttata maintains large egg size variation either in the population or in the individual. Why such phenotypic plasticity in egg size is maintained has not been clarified. In the present study we performed a series of experiments to verify whether or not females of P. g. guttata discriminate between the different host plants, i.e., rice plant Oriza sativa in the first and second generations and cogon grass Imperata cylindrica in the third (overwintering) generation and manipulate egg size accordingly on these host plants. When a caged female was allowed to lay eggs alternatively on soft-leafed rice plant and tough-leafed cogon grass, the size of the eggs laid on cogon grass was significantly larger than that on rice plant. When a caged female was allowed to lay eggs on the two host plants that were supplied on alternate days, the size of eggs laid on cogon grass was also significantly larger than that on rice plant. A preliminary experiment using crude extract from the plants suggested that females did not manipulate egg size in response to chemical stimulants alone. The skipper female was able to lay different-sized eggs instantaneously after assessing the host plant. However, the reaction norm to different host plants differed among females. Eggs of various sizes were matured in each ovariole, and egg size variation at the lowest part of the ovariole ranged from the size of the larger eggs laid on cogon grass to that of the smaller eggs laid on rice plant, although how the female chose the appropriate-sized egg at each occasion is unknown.     

CYTOKINES INVOLVING gp130 IN SIGNAL TRANSDUCTION SUPPRESSED GROWTH OF A MOUSE HYBRIDOMA CELL LINE AND ENHANCED ITS ANTIBODY PRODUCTION

Three cytokines, interleukin 6 (IL-6), leukaemia inhibitory factor (LIF), and oncostatin M (OSM), that bind to composite receptors including a common signal transducer gp130 suppressed proliferation of a mouse B-cell hybridoma cell line 2E3-O cultured in serum-free medium, while they enhanced antibody production of the cells. The specific growth rate of the cells reduced from 1.0/day for control to 0.6/day for the cultures supplemented with IL-6, LIF, or OSM at 1, 4, or 2 ng/ml, respectively. The antibody productivity increased five-fold when the cells were cultured with IL-6, LIF, or OSM at 1, 25, or 20 ng/ml, respectively. Transforming growth factor β1 (TGF-β1) similarly suppressed growth of the cells at the concentration of 5 ng/ml, while it did not enhance the antibody production. Cell cycle analysis revealed that IL-6 induced the cells to be arrested at G₁phase of the cell cycle more intensively than TGF-β1, indicating that IL-6 and TGF-β1 suppressed the growth through mutually different mechanisms. As a whole, this work suggests that gp130, which is commonly involved in each receptor for IL-6, LIF, OSM, transduces signals for suppressing proliferation and possibly for enhancing antibody production in the hybridoma cells.     

Descriptive models for the system of the natural spread of infection of rice dwarf virus (RDV) by the green rice leafhopper,Nephotettix cincticeps Uhler (Hemiptera: Deltocephalidae)

Seasonal changes in the densities of eggs and of 1st instar nymphs of N. cincticeps, a vector of the rice dwarf virus (RDV) and those in the proportion of virus-infected rice hills were examined by regular field censuses during the period of 1964–69 at two localities in Kochi, Nangoku and Ino. The proportion of virus-infected insects in the vector population was measured by the serological test. Mean fecundity of adult females of N. cincticeps in different generations was assessed by the method proposed byHokyo andKiritani (1968) in 1966 and 1967. Using observed variables as mentioned above, two mathematical models were built up for the system of the natural spread of infection of RDV. Submodels describing generation-to-generation changes in densities of eggs, 1st instar nymphs and leafhopper adults were involved in both Models 1 and 2. In Model 1, the proportion (P) of infected insects in the vector population was assumed to be determined directly by the amount (I_v) of infected rice plants in the field. In Model 2, instead of relating P directly to I_v,P was related to the acquisition rate (W) of RDV by the insects and to the effect of RDV (αr) on fecundity and survival of infected insects. Then, W was related to I_v. The estimates of P by these models fitted well to the observed values for 1st to 3rd generations but a great deviation was noted in 4th and 5th generations. For the percentage of infected rice hills, both models gave relatively good estimates in the early planted rice, though they gave overestimated values in the late planted rice.     

Corynecin (chloramphenicol analogs) fermentation studies: Selective production of Corynecin I by Corynebacterium hydrocarboclastus grown on acetate

Corynebacterium hydrocarboclastus KY 8835 grew in the acetate medium and accumulated 28mM Corynecins which was the highest production yield among the processes using various carbon sources. Selective production of Corynecin I (over 90% of all Corynecins), which had been desired for increase of the product yield, was achieved in this acetate medium. To keep the concentration of acetate, ammonium, and phosphate ions in the optimum range throughout the fermentation, a solution containing CH₃COOH (50%), CH₃COONH₄ (9%), and KH₂PO₄(0.2%) was fed continuously to the culture medium as the pH controlling agent. The addition of KCl (1%) and NaCl (1%) to the medium at 12 hr after inoculation stimulated the production of Corynecins.     

Cellular Level of Purine Compounds in Ischemic Gerbil Brain by High Performance Liquid Chromatography

Abstract: The cellular level of ATP and related compounds in ischemic gerbil brain was investigated by high performance liquid chromatography (HPLC). Brain samples were obtained in situ following ligation of the common carotid artery. AMP and ADP peaks in the brain extracts in the ischemic group became much larger whereas the ATP peak decreased dramatically. The most striking finding was an extensive increase of adenosine: 50–100 fold. The levels of inosine and hypoxanthine also increased greatly in typical symptomatic gerbil.