CDNA microarray assessment for ozone-stressed Arabidopsis thaliana

Various detrimental factors in the environment damage plants, resulting in growth inhibition or withering. However, it is not easy to identify causal factors by visually inspecting the damaged plants. Therefore, we have developed a sensitive and reliable method for plant diagnosis, based on measuring changes in expression of a set of genes in a DNA microarray. With this method, we have been able to detect and discriminate between plants stressed by ozone, drought, or wounding.     

Examination of dioxin fluxes recorded in dated aquatic-sediment cores in the Kanto region of Japan using multivariate data analysis

Past dioxin (coplanar polychlorinated biphenyl (Co-PCB), 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin (PCDD) and 2,3,7,8-substituted polychlorinated dibenzofuran (PCDF)) fluxes recorded in dated aquatic-sediment cores were analyzed using principal component analysis (PCA). The data set consisted of samples from four cores collected from the Kanto region of Japan. Time trends and spatial differences in the dioxin flux were examined, and the potential relationship to emission sources was investigated. Twenty-five compounds and 58 core slices, corresponding to the later half of the 20th century, were subjected to the analysis. The PCA of both log-transformed and maximum-value-standardized data successfully divided the dioxin compounds into a small number of groups, and three similar clusters of Co-PCBs, PCDDs and penta- to hepta-CDFs were identified. PCB formulations used in the past are judged to have been responsible for the major part of the Co-PCB flux recorded in the sediment cores. However, the relationship to emission sources needs further investigation. It is suggested that most 2,3,7,8-substituted PCDDs and PCDFs are different from Co-PCBs in their emission sources or movements in the environment. The subcore clusters obtained from the PCA of log-transformed data show that the cores from different sampling areas exhibited distinct dioxin fluxes and compositions. Common time trends among the cores were more effectively summarized by the PCA of maximum-value-standardized data focusing on relative time trends. PC scores show that recently the flux of each dioxin compound in the four cores has been generally declining after having reached a peak.     

Bioconcentration factor of relatively low concentrations of chlorophenols in Japanese medaka

Bioconcentration factors (BCF) for pentachlorophenol (PCP) and 2,4-dichlorophenol (2,4-DCP) in Japanese medaka (Oryzias latipes) were determined at five different concentrations of the chemicals, between 0.1 and 10 microg/l (PCP), 0.3 and 30 microg/l (2,4-DCP), in the ambient water. Medaka were exposed to each chemicals in a continuous-flow system during the embryonic development period and 60 days after hatching from eggs collected in the laboratory. Both the exposure time and the aqueous concentrations are much more realistic and closer to natural aquatic environments than those used in conventional BCF studies. The BCF values of PCP were from (4.9+/-2.8)x10(3) at the aqueous concentration of 0.074+/-0.028 microg/l to (2.1+/-1.4)x10(3) at 9.70+/-0.56 microg/l. The BCF value of 2,4-DCP were from (3.4+/-3.0)x10(2) at 0.235+/-0.060 microg/l to 92+/-27 at 27.3+/-1.6 microg/l. Generally, BCF values increased as the aqueous concentrations of PCP or 2,4-DCP decreased. This finding suggests that a relatively low and realistic aqueous concentration of these compounds is necessary to more accurately determine their BCF values in natural aquatic environments. Conventional BCF experiments at higher aqueous concentrations may underestimate the BCF values.     

Biofilm formation and lipopeptide antibiotic iturin A production in different peptone media

Biofilm fermentation is a newly developed promising technique in fermentation technology. In this study no.3 and no.3S media have been used for the lipopeptide antibiotic iturin A production by Bacillus subtilis RB14. The main component of no.3 and no.3S media is Polypepton and Polypepton S, respectively. B. subtilis RB14 produces thick stable biofilm and high amount of iturin A in no.3S medium. Whereas, impaired biofilm formation and lower iturin A production was observed in no.3 medium. From the analytical information it was observed that the amounts of metal ions, such as K⁺, Ca²⁺ and Mn²⁺, cysteine and cellulose are lower in Polypepton compared to the Polypepton S. To investigate their effect on biofilm formation and iturin A production cysteine, cellulose, K⁺, Ca²⁺ and Mn²⁺ were added respectively into the no.3 medium at similar amount that Polypepton S contains. It was observed that individual addition of K⁺, Ca²⁺, cysteine and cellulose had no effect on biofilm formation, cellular growth induction or iturin A production. However, when Mn²⁺ was supplemented in no.3 medium, biofilm development was restored with an improved production of iturin A. Finally, combined addition of investigated substances into the no.3 medium resulted with highly folded, thick biofilm with high cellular growth and iturin A production compared to the original no.3 medium.     

Gonadotropic effects of dopamine in isolated workers of the primitively eusocial wasp, Polistes chinensis

In social insects, biogenic amines are thought to play regulatory roles in the transition between reproductive states in females. To determine the effect of dopamine on the reproductive development of workers in primitively eusocial societies, isolated workers of the paper wasp Polistes chinensis were supplied with oral dopamine. Ovarian development was accelerated in dopamine-fed workers as compared to control workers of the same age fed only sucrose solution. Oral dopamine increased brain levels of dopamine and its metabolite (N-acetyldopamine). Brain levels of tyramine or octopamine were also increased by dopamine application in one of two colonies; levels of the tyramine metabolite N-acetyltyramine were unchanged. These results indicate that dopamine plays a gonadotropic role in isolated workers in the primitively eusocial wasp, similar to the gonadotropic role previously reported for juvenile hormone. This is the first study to report effects of dopamine on ovarian development in workers of the paper wasp.     

Sugar receptor response of the food-canal taste sensilla in a nectar-feeding swallowtail butterfly, Papilio xuthus

The feeding behavior in nectar-feeding insects is triggered by a sugar-receptor response in contact chemosensilla. The contact chemosensilla are distributed not only on tarsi and the outside of the proboscis but also on the inside of the food canal in Lepidoptera. Although the chemosensilla inside the food canal are assumed to detect sweet taste during the passage of nectar through the food canal, their electrophysiological function has received little attention. In the nectar-feeding Asian swallowtail butterfly, Papilio xuthus (Lepidoptera: Papilionidae), we found 15- to 30-μm-long sensilla neatly lined up along the inside galea wall, which forms the food canal in the proboscis. The receptor neurons of these sensilla responded to sucrose. We hypothesized that starch and sucrose compete with each other for a taste receptor site on the sensilla. When we added starch and sucrose to the food-canal sensilla, the electrophysiological responses of food-canal sensilla were inhibited in parallel with the food-sucking behavior of the butterflies. These results suggest that the food-canal sensilla are involved in the behavioral control of nectar-sucking in this butterfly species.     

Pharmacophagous acquisition of clerodendrins by the turnip sawfly (Athalia rosae ruficornis) and their role in the mating behavior

Summary. Adults of the turnip sawfly, Athalia rosae ruficornis (Tenthredinidae: Hymenoptera), frequently visit a plant, Clerodendron trichotomum (Verbenaceae), and feed pharmacophagously on the glandular trichomes on the leaf surface. A series of neo-clerodane diterpenoids (e.g. clerodendrins B and D) contained in glandular organs on the leaf surface stimulate feeding of the sawflies (both males and females). The adults fed selectively on the trichomes were found to sequester a series of the bitter-tasting diterpenes (clerodendrin D, ajugachin A, athaliadiol) in the body tissues, which suggested their primary role as defense substances against predators. Females fed on Clerodendron leaves or on clerodendrin B or D were more successful in mating than unfed females. Thus, females seem to obtain an advantage in mating success through the acquisition of the defensive principles from the Clerodendron plant. Received 20 April 1999; accepted 29 June 1999     

Simulation of long-term nutrient removal in a full-scale closed-loop bioreactor for sewage treatment: an example of Bayesian inference

In this study, the performance of nitrogen and phosphorus removal in a full-scale closed-loop bioreactor (oxidation ditch) system was simulated using the ASM2d model. Routine data describing the process for two years were compiled for calibration and validation. To overcome the identifiability problem, the classic Bayesian inference approach was utilized for parameter estimation. The calibrated model could describe the long-term trend of nutrient removal and short-term variations of the process performance, showing that the Bayesian method was a reliable and useful tool for the parameter estimation of the activated sludge models. The anoxic phosphate uptake by polyphosphate accumulating organisms (PAO) contributed 71.2% of the total Poly-P storage, which reveals the dominance of denitrifying phosphorus removal process under the oxygen limiting conditions. It was found that 58.7% of the anoxic Poly-P storage and denitrification by PAO in the reactor was achieved in the aerated compartment, implying that the PAO’s anoxic activity was significantly stimulated by the low dissolved oxygen (DO) level in this compartment due to the oxygen gradient caused by brush aerator.     

Photosynthetic and growth responses of Japanese sasabamo (Potamogeton wrightii Morong) under different photoperiods and nutrient conditions

Controlled laboratory experiments were conducted to examine how photosynthesis and growth occur in Potamogeton wrightii Morong under different photoperiods and nutrient conditions. The experiment was based on a 3×2 factorial design with three photoperiods (16, 12 and 8 h) of 200 μE · m^?2·s^?1 irradiance and two nutrient conditions, high (90 μmol N · L^?1·d^?1 and 9 μmol P · L^?1·d^?1) and low (30 μmol N L^?1·d^?1 and 3 μmol P · L^?1·d^?1). After 14, 28, 56 and 70 days of growth, plants were harvested to determine net photosynthesis rate and various growth parameters. Above- and below-ground biomass were investigated on days 56 and 70 only. Plants under low nutrient conditions had greater leaf area, more chlorophyll a, a higher rate of net photosynthesis and accumulated more above- and below-ground biomass than plants in the high nutrient condition. Plants with an 8 h photoperiod in the low nutrient condition had a significantly higher rate of net photosynthesis, whereas 8 h photoperiod plants in the high nutrient condition had a lower rate of net photosynthesis and their photosynthetic capacity collapsed on day 70. We conclude that P. wrightii has the photosynthetic plasticity to overcome the effects of a shorter photoperiod under a tolerable nutrient state.