Algicidal effect of 3-(3-indolyl)butanoic acid, a control agent of the bacterial wilt pathogen, Ralstonia solanacearum

The chemical control agent 3-(3-indolyl)butanoic acid, previously reported as a control agent for the bacterial wilt pathogen Ralstonia solanacearum, was shown to suppress the growth of green algae during hydroponic culture of tomato. The algicidal activity of the compound was effective at 10 μg/ml, completely preventing generation of green algae under non-shaded greenhouse conditions. The algicidal effect was mainly due to suppression of the growth of motile unicellular algal cells tentatively identified as Chlamydomonas spp., which are commonly occurring in the hydroponic solution and vigorously multiply to form an algal mat on the sponge supports. The compound has potential as a non-phytotoxic algicide for hydroponically cultured crop plants.     

Enhancement of flicker by lateral inhibition

Sinusoidal modulation of illumination on the compound eye of the horseshoe crab, Limulus, produces a corresponding variation in the rate of discharge of optic nerve impulses. Increasing the area of illumination decreases the variation at low frequencies of modulation, but unexpectedly enhances-or "amplifies"-the variation at the intermediate frequencies to which the eye is most sensitive. Both effects must result from inhibition since it is the only significant lateral influence in this eye.     

CEP peptide induces susceptibility of Arabidopsis thaliana to non-adapted pathogens

CEP peptide was synthesized and tested for induction of disease susceptibility using Arabidopsis Col-0. When Colletotrichum tropicale was used as a non-adapted fungal pathogen, the conidia germinated to form hyphal-like structures, which successfully penetrated epidermis, eventually causing disease symptoms. In such case, PEN2-, but not PEN3-dependent resistance was likely suppressed by CEP peptide. Similarly, the CEP peptide-mediated disease susceptibility was also effective to a non-adapted bacterial pathogen. Notably, such induced susceptibility was also evident on Arabidopsis mutants lacking the previously identified receptors, suggesting that the CEP peptide modulates Arabidopsis immunity through an unidentified receptor(s).

     

Early detection of urinary bladder carcinogens in rats by immunohistochemistry for γ-H2AX: a review from analyses of 100 chemicals

In safety evaluations of chemicals, there is an urgent need to develop short-term methods to replace long-term carcinogenicity tests. We have reported that immunohistochemistry for γ-H2AX, a well-established biomarker of DNA damage, can detect bladder carcinogens at an early stage using histopathological specimens from 28-day repeated-dose oral toxicity studies in rats. Given the markedly low level of γ-H2AX formation in the bladder urothelium of untreated rats, an increase in γ-H2AX-positive cells following chemical exposure can be relatively easy to identify. Among the 100 compounds examined to date, bladder carcinogens can be detected with high sensitivity (33/39; 84.6%) and specificity (58/61; 95.1%). As expected, γ-H2AX formation levels tended to be high following exposure to genotoxic bladder carcinogens, whereas nongenotoxic bladder carcinogens also increased the number of γ-H2AX-positive cells, probably through secondary DNA damage associated with sustained proliferative stimulation. γ-H2AX formation in the bladder urothelium reflects species differences in susceptibility to bladder carcinogenesis between rats and mice and shows a clear dose-dependency associated with the intensity of tumor development as well as high reproducibility. Some of the bladder carcinogens that showed false-negative results in the evaluation of γ-H2AX alone could be detected by combined evaluation with immunostaining for bladder stem cell markers, including aldehyde dehydrogenase 1A1. This method may be useful for the early detection of bladder carcinogens, as it can be performed by simple addition of conventional immunostaining using formalin-fixed paraffin-embedded tissues from 28-day repeated-dose toxicity studies in rodents, which are commonly used in safety evaluations of chemical substances.     

Mineral Composition of Clay Fractions and Oxygen Vacancies in Silt-Sized Quartz in Soils on the Ka-Etsu Plateau, Fukui, Central Japan—Possibility of Eolian Dust Brought from Northern Asia as Parent Material of Soils

Fine- to medium-textured soils are distributed on the Early Pliocene rocks and Pleistocene sandy sediments in the Ka-Etsu plateau. The Jingaoka (JIN) soil was classified into Aluandic Andosols by WRB, and Low-humic Non-allophanic Kuroboku soils by the Fourth Committee for Soil Classification and Nomenclature of the Japanese Society of Pedology, although it was similar morphologically to Yellow-Brown Forest soils. On the other hand, the Tomitsu (TMI) and Yamamuro (YAM) soils were classified into Hyperdystri-Chromic Cambisols by WRB, and Typic Yellow-Brown Forest soils by the Fourth Committee for Soil Classification and Nomenclature based on the morphological, physical and chemical properties. These soils were influenced considerably by the Akahoya tephra, especially the JIN soil. Based on the results of clay-mineralogical analysis and the measurement of the ESR-signal intensity associated with the oxygen vacancies in fine quartz, a large part of parent materials in the soils distributed on the Ka-Etsu plateau was derived from the eolian dust which was brought with the NW winter monsoon from the Precambrian sediments in the northern part of the Asian continent during MIS 2 (24–11 thousand years ago) at the Last Glacial Maximum. The parent materials of the fine-textured JIN soil located on the highest terrace near the rocky coastline were mostly composed of eolian dust, although the influenced of the Akahoya tephra was recognized. The parent materials of the TMI soil were admixed with a small amount of autochthonous materials from the sandy coast located windward. In the YAM soil which was located on the side of a hilly area distant from the coastline, the ESR-signal intensity in fine quartz was considerably low, and the admixture of autochthonous materials was also considered since the texture of this soil was coarser than that of the JIN and TMI soils.     

Characterization of the suppressive effects of the biological control strain VAR03-1 of <Emphasis Type="Italic">Rhizobium vitis</Emphasis> on the virulence of tumorigenic <Emphasis Type="Italic">R. vitis</Emphasis>

Rhizobium vitis: strain VAR03-1 is a biological control agent that suppresses grapevine crown gall disease caused by a tumorigenic strain of R. vitis (Ti). Both acetosyringone-induced expression of a virulence gene and the growth of Ti were suppressed in vitro when it was cultivated in the VAR03-1 culture filtrate. These inhibitory effects were reduced by high-temperature treatment or incubation for 72 h. Both activities were detected in the high molecular weight fraction (>?100 kDa) of the filtrate. Our results suggest that the antagonistic effects of VAR03-1 on Ti are mediated by large particle(s) released in the culture media.     

An electric field strongly deters whiteflies from entering window-open greenhouses in an electrostatic insect exclusion strategy

Dual functions (insect repelling and capturing) of a single-charged dipolar electric field screen were evaluated to successfully exclude whiteflies from a window-open greenhouse. The screen consisted of three parts: 1) insulated conductor wires (ICWs) arrayed in parallel at 5?mm intervals, 2) two earthed stainless nets placed within 3?mm of both sides of the ICW layer, and 3) a voltage generator for the negatively charged ICWs. The screen formed two electric fields between the ICW-layer and the ICW-side surface of the earthed net and between the ICWs. At negative charging of 1.5–2.5?kV, all whiteflies reaching the outer surface of the screen net avoided entering the electric field and flew away from the screen. This avoidance was disturbed by 3?m s^?1 wind, as the insects were compulsorily blown inside. However, almost all whiteflies (99.4?%) were captured with the ICW. These results indicate that the insect-capturing function is effective to complement a failure to repel. A greenhouse assay was conducted in the screen-attached and non-screened parts in which a greenhouse was divided with a partition. During the 3-month operation, the screen was durable and functional for excluding pests, and better air ventilation changed the climate conditions in the greenhouse. Thus, the present study demonstrated that our electric field screen can provide an airy condition for tomatoes in a window-open greenhouse and successfully exclude whiteflies using dual screen functions.     

The Intravenous Xylitol Tolerance Test in Non-Lactating Cattle

Xylitol is a five-carbon sugar alcohol that is often used for treatment of ketosis in dairy cattle in Japan. An intravenous xylitol tolerance test (IVXTT, 0.1 g/kg, bolus injection through the jugular vein) was performed in 4 non-lactating cows (n = 4) and the results were compared with those of an intravenous glucose tolerance test (IVGTT) performed under equivalent conditions. The serum xylitol concentration reached a peak value (41.4±9.0 mg/dl) at 5 min, and then rapidly decreased and almost disappeared within 2 h. The C ₀ for xylitol was 56.9±16.6 mg/dl and the t _1/2was 8.5±0.9 min. The administration of xylitol appeared to cause similar secretion of insulin to that caused by glucose. There was also a reduction in the concentration of free fatty acids. It seems that xylitol has value for the treatment of ketosis. However, rapid administration of xylitol appeared to have an osmotic diuretic action and might be a cause of dehydration.     

Regulation of elicitin-induced ethylene production in suspension-cultured tobacco BY-2 cells

INF1 elicitin, a proteinaceous elicitor produced by Phytophthora infestans, induces a hypersensitive response in tobacco BY-2 cells. In response to elicitin, tobacco cells produce both reactive oxygen species (ROS) and ethylene (ET). To investigate the regulation of elicitin-induced ET production, we pharmacologically analyzed the effects of several chemicals on ET production. Inhibitors of ROS generation or ROS chelators efficiently inhibited ET production, whereas simultaneous treatment of a superoxide anion-generating system with salicylhydroxamic acid recovered ET production. In an in vitro experiment, superoxide anion was necessary and sufficient for conversion of 1-aminocyclopropane-1-carboxylate (ACC) to ET because ET was produced from ACC solely in the presence of the superoxide-generating chemical KO₂. ET production was also inhibited by lipoxygenase (LOX) inhibitors, indicating a possible involvement of LOX-mediated generation of superoxide anion and ET production itself. Furthermore, elicitin-induced ET production was completely inhibited by the protein synthesis inhibitor cycloheximide but recovered after exogenous application of ACC, indicating that de novo protein synthesis is required for ACC accumulation, leading to ET production. We also investigated the effects of several phytohormones on elicitor-induced ET production and discuss their role in the defense response.