Purification and Properties of Dihydrostreptomyein-Phosphorylating Enzyme from Pseudomonas aeruginosa

The distribution of the dihydrostreptomycin (DHSM)-phosphorylating enzyme was investigated using DHSM-resistant strains of Pseudomonas aeruginosa, indicating that this enzyme was demonstrated from all of 7 DHSM-resistant strains examined but not from a DHSM-sensitive one. The DHSM-phosphorylating enzyme was isolated from P. aeruginosa TI-13 and purified about 205-fold using Sephadex G-75 and DEAE-Sephadex A-50 column chromatography. The optimal pH for the DHSM-inactivation was around 10.0, and both adenosinetriphosphate (ATP) and Mg⁺⁺ were required for the inactivating reaction. It was found that this enzyme inactivated only DHSM but not other aminoglycosidic antibiotics such as kanamycin, aminodeoxykanamycin, neomycin, paromomycin, lividomycin and gentamicin.     

Isolation and characterization of an extremely thermophilic,cellulolytic, anaerobic bacterium

Summary A cellulolyticm obligately anaerobic, extreme thermophile (strain NA10) was isolated from an alkaline hot spring in Nagano Prefecture, Japan. The microorganism was a non-spore-forming, flagellated rod which had a negative reaction to Gram stain, and occurred singly or in pairs. The growth temperature was between 50° C and 85° C with the optimum at 75° C, and the growth pH was between 6.0 and 9.5 with the optimum at 8.1. The anaerobe characteristically fermented cellulose, and produced acetic acid, H₂, CO₂ (main products) and lactic acid (minor product). The DNA had a base composition of 37.7 mol% guanine+cytosine content.     

Thy-1 inhibits mitogen-induced Ca2+ oscillation in ras-transformed mouse fibroblasts.

Cell surface glycoprotein Thy-1 functions as a transformation suppressor in v-ras-transformed NIH/3T3 cells [Sugimoto et al., (1991) Cancer Res. 51, 99-104.]. In order to understand the mechanism of action of Thy-1, we examined the effect of Thy-1 expression on mitogen-induced Ca2+ oscillation which was correlated with v-ras-transformation [Fu et al., (1991) FEBS Lett. 281, 263-266.]. Forced expression of Thy-1 in v-ras-transformed cells inhibited mitogen-induced Ca2+ oscillation. Although v-Ras-free, Thy-1-positive NIH/3T3 cells (major population) did not show Ca2+ oscillation, whereas in Thy-1-negative NIH/3T3 cells (less than 1% of the population) Ca2+ oscillation was observed. Finally, replacement of the carboxyl-half of Thy-1 with that of CD4 abolished the inhibitory effect of Thy-1. These results suggest that Thy-1 directly or indirectly participates in the negative regulation of Ca2+ response by inhibiting Ca2+ oscillation.     

Phylogeography,Interaction Patterns and the Evolution of Host Choice in Drosophila-Parasitoid Systems in Ryukyu Archipelago and Taiwan

Island biotas provide a great opportunity to study not only the phylogeographic patterns of a group of species, but also to explore the differentiation in their coevolutionary interactions. Drosophila and their parasitoids are exemplary systems for studying complex interaction patterns. However, there is a lack of studies combining interaction-based and molecular marker-based methods. We applied an integrated approach combining phylogeography, interaction, and host-choice behavior studies, with the aim to understand how coevolutionary interactions evolve in Drosophila-parasitoid island populations. The study focused on the three most abundant Drosophila species in Ryukyu archipelago and Taiwan: D. albomicans, D. bipectinata, and D. takahashii, and the Drosophila-parasitoid Leptopilina ryukyuensis. We determined mitochondrial COI haplotypes for samples representing five island populations of Drosophila and four island populations of L. ryukyuensis. We additionally sequenced parts of the autosomal Gpdh for Drosophila samples, and the ITS2 for parasitoid samples. Phylogenetic and coalescent analyses were used to test for demographic events and to place them in a temporal framework. Geographical differences in Drosophila-parasitoid interactions were studied in host-acceptance, host-suitability, and host-choice experiments. All four species showed species-specific phylogeographic patterns. A general trend of the haplotype diversity increasing towards the south was observed. D. albomicans showed very high COI haplotype diversity, and had the most phylogeographically structured populations, with differentiation into the northern and the southern population-group, divided by the Kerama gap. Differentiation in host suitability was observed only between highly structured populations of D. albomicans, possibly facilitated by restricted gene flow. Differentiation in host-acceptance in D. takahashii, and host-acceptance and host-choice in L. ryukyuensis was found, despite there being no differentiation in these two species according to molecular markers. Host choice assays show that L. ryukyuensis populations that have had more time to coevolve adapt their behavior to exploit the most suitable host – D. albomicans. L. ryukyuensis parasitoids on border ranges may, on the other hand, benefit from broader host-acceptance, that may facilitate adaptation to uncertain and variable environments. All results indicate that Drosophila-parasitoid populations in the Ryukyu archipelago and Taiwan have different evolutionary trajectories, and coevolve in a dynamic, complex, and local-specific way.     

Reduced Pain and Inflammation in Juvenile and Adult Rats Fed a Ketogenic Diet

The ketogenic diet is a high-fat, low-carbohydrate regimen that forces ketone-based rather than glucose-based cellular metabolism. Clinically, maintenance on a ketogenic diet has been proven effective in treating pediatric epilepsy and type II diabetes, and recent basic research provides evidence that ketogenic strategies offer promise in reducing brain injury. Cellular mechanisms hypothesized to be mobilized by ketone metabolism and underlying the success of ketogenic diet therapy, such as reduced reactive oxygen species and increased central adenosine, suggest that the ketolytic metabolism induced by the diet could reduce pain and inflammation. To test the effects of a ketone-based metabolism on pain and inflammation directly, we fed juvenile and adult rats a control diet (standard rodent chow) or ketogenic diet (79% fat) ad libitum for 3–4 weeks. We then quantified hindpaw thermal nociception as a pain measure and complete Freund''s adjuvant-induced local hindpaw swelling and plasma extravasation (fluid movement from the vasculature) as inflammation measures. Independent of age, maintenance on a ketogenic diet reduced the peripheral inflammatory response significantly as measured by paw swelling and plasma extravasation. The ketogenic diet also induced significant thermal hypoalgesia independent of age, shown by increased hindpaw withdrawal latency in the hotplate nociception test. Anti-inflammatory and hypoalgesic diet effects were generally more robust in juveniles. The ketogenic diet elevated plasma ketones similarly in both age groups, but caused slowed body growth only in juveniles. These data suggest that applying a ketogenic diet or exploiting cellular mechanisms associated with ketone-based metabolism offers new therapeutic opportunities for controlling pain and peripheral inflammation, and that such a metabolic strategy may offer significant benefits for children and adults.     

Migration of exogenous immature hematopoietic cells into adult mouse brain parenchyma under GFP-expressing bone marrow chimera.

Bone marrow transplantation with GFP-expressing cells from GFP-transgenic mice resulted in migration of GFP-positive cells into peripheral tissues and brain parenchyma. Most of these cells were observed as colony-like clusters. GFP-positive clusters in the brain were stained by antibody for ER-MP12, but those in the peripheral tissues were not. Since ER-MP12 antigen has been reported as a marker for murine early-stage myeloid precursor, this might suggest that some parts of phagocytic cells in the brain parenchyma such as microglia are derived from undifferentiated pluripotent hematopoietic cells.     

Book Reviews

Book reviewed in this article:
Narody Afriki [The Peoples of Africa]. D. A. Ol'derogge and I. I. Potekhin.
Die Völker Afrikas: Ihre Vergangenheit und Gegenwart. D. A. Ol'derogge and I. I. Potekhin.     

Production of Acetone and Butanol Using Immobilized Growing-cells of Clostridium acetobutylicum

The biosynthetic route for chloromonilicin, an antifungal substance from cherry rot fungus, was investigated using deuterium-labeled precursors. The incorporation of synthetic deuterium-labeled moniliphenone into chloromonilicin and into its xanthone precursor, 4-chloropinselin, was confirmed by ’H-NMR spectrometry.