Localization of P42 and F1-ATPase α-Subunit Homolog of the Gliding Machinery in Mycoplasma mobile Revealed by Newly Developed Gene Manipulation and Fluorescent Protein Tagging

Mycoplasma mobile has a unique mechanism that enables it to glide on solid surfaces faster than any other gliding mycoplasma. To elucidate the gliding mechanism, we developed a transformation system for M. mobile based on a transposon derived from Tn4001. Modification of the electroporation conditions, outgrowth time, and colony formation from the standard method for Mycoplasma species enabled successful transformation. A fluorescent-protein tagging technique was developed using the enhanced yellow fluorescent protein (EYFP) and applied to two proteins that have been suggested to be involved in the gliding mechanism: P42 (MMOB1050), which is transcribed as continuous mRNA with other proteins essential for gliding, and a homolog of the F₁-ATPase α-subunit (MMOB1660). Analysis of the amino acid sequence of P42 by PSI-BLAST suggested that P42 evolved from a common ancestor with FtsZ, the bacterial tubulin homologue. The roles of P42 and the F₁-ATPase subunit homolog are discussed as part of our proposed gliding mechanism.     

Inhibition of Topoisomerases by Fatty Acids

The inhibitory effects of various fatty acids on topoisomerases were examined, and their structure-activity relationships and mechanism of action were studied. Saturated fatty acids (C_6:0 to C_22:0) did not inhibit topoisomerase I, but cis-unsaturated fatty acids (C_16:1 to C_22:1) with one double bond showed strong inhibition of the enzyme. The inhibitory potency depended on the carbon chain length and the position of the double bond in the fatty acid molecule. The trans-isomer, methyl ester and hydroxyl derivative of oleic acid had no or little inhibitory effect on topoisomerases I and II. Among the compounds studied petroselinic acid and vaccenic acid (C_18:1) with a cis-double bond were the potent inhibitors. Petroselinic acid was a topoisomerase inhibitor of the cleavable complex-nonforming type and acted directly on the enzyme molecule in a noncompetitive manner without DNA intercalation.     

Effect of carotenoid deficiency on photosensitivities in the silkworm, Bombyx mori

The silkworm, Bombyx mori, was reared aseptically on a synthetic diet with and without β-carotene and the effects of carotenoid and vitamin A deficiency on photosensitivities in larval phototaxis, visual function and adult eclosion were studied.β-Carotene or vitamin A acted as a growth-promoting factor in continuous darkness and under photoperiodic conditions. The deficiency of β-carotene decreased the larval phototactic response as growth proceeded. The offspring larvae from eggs laid by β-carotene-deficient moths also lost the phototactic response, but successive rearing with dietary β-carotene or vitamin A re-established the response. The deficiency of β-carotene caused the loss of the electric response by light stimuli in the ocelli of fifth instar larvae and the compound eyes of adult moths. These results indicate that vitamin A is essential for visual function in the silkworm, as reported in other insects. The lack of carotenoid did not affect the development of the pupae or the specific time of eclosion which is regulated by a photoperiodic condition of pupal stage. This observation suggests that the carotenoid and its derivative are not involved in photoreception for the entrainment of the adult eclosion of the silkworm.     

Ultrastructural analysis of the developing follicle during early vitellogenesis in tilapia,Oreochromis niloticus,with special reference to the steroid-producing cells

The development and distribution of steroid producing cells (SPCs) in the ovary of tilapia have been studied by light and electron microscopy. At 40–50 d after hatching, these cells are seen only in the vicinity of blood vessels; there are no SPCs in the interstitial region, nor in the thecal layer enclosing young oocytes at the peri-nucleolus stage. By 70–80 d after hatching, the number of SPCs in the area near blood vessels has increased, and the capillaries have spread among the developing peri-nucleolar stage oocytes, and into the ovarian tunica. Clusters of SPCs have also migrated into the interstitial region and into the tunica along with these capillaries. In the ovary 100 d after hatching, some SPCs can be found in the thecal layer enclosing vitellogenic oocytes. Moreover, masses of SPCs can now be observed infiltrating the thecal layer of the oocyte. Serum testosterone (T) and estradiol-17 (E2) levels at 40–70 d after hatching, are low (T, 0.75–1.10 ng/ml, E2, 0.36–1.08 ng/ml), but at 100 d, plasma E2, but not T, is elevated (T, 1.95 ng/ml, E2, 4.65 ng/ml). These results suggest that SPCs appearing in the vicinity of blood vessels move into the interstitial region between oocytes, and finally enclose the oocytes at an early vitellogenic stage. It is interesting to note that the enclosure of oocytes by SPCs coincides with significant increases in E2 production.     

An Alkalophilic Bacillus sp. Produces 2-Phenylethylamine

A large amount of 2-phenylethylamine was produced in cells of alkalophilic Bacillus sp. strain YN-2000. This amine is secreted in the medium during the cell growth. The amounts of 2-phenylethylamine in both cells and medium change upon changing the pH of the medium.     

Calcium Permeability of Non-N-Methyl-D-Aspartate Receptor Channels in Immature Cerebellar Purkinje Cells: Studies Using Fura-2 Microfluorometry

Abstract: Using fura-2 microfluorometry, I investigated the mechanism by which non-N-methyl-d -aspartate (NMDA) receptor agonists increase the cytosolic free calcium concentration ([Ca]_in) in single cerebellar Purkinje cells isolated from 3–10-day-old rats. Kainate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate dose-dependently increased the cytosolic free Na⁺ concentration, which was measured using sodium-binding benzofuran isophthalate microfluorometry, confirming the Na⁺ influx through ion channels linked to non-NMDA receptors. The [Ca²⁺] increases induced by relatively lower concentrations of agonists were entirely dependent on external Ca²⁺ and were reduced by removal of external Na⁺ or by addition of a Ca²⁺ channel blocker, D600. The results indicate that the non-NMDA agonist–induced [Ca]_in increase was due mainly to Ca²⁺ influx through voltage-dependent Ca²⁺ channels, which were activated by a massive Na⁺ influx. On the other hand, higher concentrations of agonists dose-dependently increased [Ca]_in under conditions in which activation of voltage-dependent Ca²⁺ channels were blocked by a combination of Na⁺ removal with D600. These [Ca]_in increases were Ca²⁺ dependent and little affected by adding a competitive NMDA antagonist. Non-NMDA agonists also stimulated influxes of Mn²⁺ and Co²⁺, both of which can be monitored by quenching fura-2 fluorescence under the same conditions. These results suggest that ion channels linked to non-NMDA receptors on immature Purkinje cells are permeable to Ca²⁺, Mn²⁺, and Co²⁺.     

Plant regeneration from cell suspension-derived protoplasts of Saintpaulia ionantha Wendl

Summary Friable calli were induced on leaf segments of Saintpaulia ionantha Wendl. on B5 medium containing 1 mg l^–1 2,4-D and 2 g l^–1 casein hydrolysate. Cell suspension cultures were readily established from these friable calli and protoplasts could be isolated from the cells with yields of 1–3×10⁷/g f. wt.. By culturing in 0.1 % gellan gum-solidified B5 medium supplemented with 1 mg l^–1 2,4-D and 0.1 M each of sucrose and mannitol at a density of 1×10⁵/ml, the protoplasts divided within 6 days and formed macro-colonies after 2 months of culture. Shoot regeneration from protoplast-derived calli was obtained by sequential treatment of the calli with plant growth regulators: initially with 1 mg l^–1 each of NAA and BA for 2 months followed by 0.01 mg l^–1 NAA and 5 mg l^–1 BA for 4 months. Regenerated plants were established after rooting of the shoots on half-strength MS medium, and successfully transferred to the greenhouse. The regenerated plants grew into flowering stage and showed the same phenotype as the parent plant.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - FDA fluorescein diacetate - f. wt fresh weight - MES 2-(N-morpholino)-ethanesulfonic acid - MS Murashige and Skoog (1962) - NAA -naphthaleneacetic acid - PE plating efficiency     

Cytokine-gene-modified tumor vaccination intensified by a streptococcal preparation OK-432

Vaccinations with tumor cells engineered to express certain cytokines have been demonstrated to induce potent and specific antitumor immunity. In our previous report, we carried out a comparative study on the ability of cytokine-gene-modified tumor vaccines to induce host immune responses, and found that irradiated tumor cells, genetically modified to secrete granulocyte/macrophagecolony-stimulating factor (GM-CSF tumor vaccine), were the most potent stimulators of systemic antitumor immunity. In this report, using the experimental tumor models in which the GM-CSF tumor vaccine was less effective in immunopotentiation, we found that the combined use of a biological response modifier (BRM) OK-432 remarkably enhanced the antitumor activity induced by the GM-CSF tumor vaccine. These data indicate the possible role of a BRM such as OK-432 to intensify further the specific tumor vaccination therapy.     

Short Communication: Ames assay with Salmonella typhimurium TA102 for mutagenicity and antimutagenicity of metallic oxide powders having antibacterial activities

Metallic oxide powders (magnesium oxide, calcium oxide and zinc oxide) having antibacterial activity were examined for their mutagenicity and antimutagenicity by the Ames test with Salmonella typhimurium TA 102. These powders were not mutagenic to the tester strain and reduced the mutagenicity of methylglyoxal.