Investigation of concentrations of paddy herbicides and their transformation products in the Sakura River, Japan, and toxicity of the compounds to a diatom and a green alga.

Four paddy herbicides and their transformation products (TPs) were monitored in the Sakura River, Japan, during the rice growing seasons of 2009 and 2010. Toxicity tests to an attached diatom, Mayamaea atomus, and a green alga, Pseudokirchneriella subcapitata, were also conducted. Clomeprop propionic acid, which forms from the degrading herbicide, was detected in the river water at much higher concentrations than the parent compound (the maximum concentration of the TP and the parent compound; 0.

A macro-scale perspective on within-farm management: how climate and topography alter the effect of farming practices.

Organic farming has the potential to reverse biodiversity loss in farmland and benefit agriculture by enhancing ecosystem services. Although the mixed success of organic farming in enhancing biodiversity has been attributed to differences in taxa and landscape context, no studies have focused on the effect of macro-scale factors such as climate and topography. This study provides the first assessment of the impact of macro-scale factors on the effectiveness of within-farm management on biodiversity, using spiders in Japan as an example.

Biodegradation of endosulfan by Mortieralla sp. strain W8 in soil: Influence of different substrates on biodegradation.

To examine the bioremediation potential of Mortierella sp. strain W8 in endosulfan contaminated soil, the fungus was inoculated into sterilized and unsterilized soil spiked with endosulfan. Wheat bran and cane molasses were used as substrates to understand the influence of different organic materials on the degradation of endosulfan in soil.

Reduction in uptake by rice and soybean of aromatic arsenicals from diphenylarsinic acid contaminated soil amended with activated charcoal.

Activated charcoal (AC) amendment has been suggested as a promising method to immobilize organic contaminants in soil. We performed pot experiments with rice and soybean grown in agricultural soil polluted by aromatic arsenicals (AAs). The most abundant AA in rice grains and soybean seeds was methylphenylarsinic acid (MPAA).

Spatial variation in photosynthetic CO(2) carbon and oxygen isotope discrimination along leaves of the monocot triticale (Triticum × Secale) relates to mesophyll conductance and the Péclet effect.

Carbon and oxygen isotope discrimination of CO(2) during photosynthesis (Δ(13)C(obs) and Δ(18)O(obs)) were measured along a monocot leaf, triticale (Triticum × Secale). Both Δ(13)C(obs) and Δ(18)O(obs) increased towards the leaf tip. While this was expected for Δ(18)O(obs) , because of progressive enrichment of leaf water associated with the Péclet effect, the result was surprising for Δ(13) C(obs).

A survey of the cellular responses in Pseudomonas putida KT2440 growing in sterilized soil by microarray analysis.

Genome-wide scanning of gene expression by microarray techniques was successfully performed on RNA extracted from sterilized soil inoculated with Pseudomonas putida KT2440/pSL1, which contains a chloroaromatic degrading plasmid, in the presence or absence of 3-chlorobenzoic acid (3CB). The genes showing significant changes in their expression in both the triplicate-microarray analysis using amplified RNA and the single-microarray analysis using unamplified RNA were investigated. Pathway analysis revealed that the benzoate degradation pathway underwent the most significant changes following treatment with 3CB.

Effect of soil type and fertilizer management on archaeal community in upland field soils.

The effects of soil and fertilizer types on archaeal communities were evaluated by real-time PCR and PCR-denaturing gradient gel electrophoresis (DGGE) targeting the 16S rRNA gene of total DNA directly extracted from upland field soils. Twelve experimental upland field plots containing four different soil types, i.e.

Effects of four rice paddy herbicides on algal cell viability and the relationship with population recovery.

Paddy herbicides are a high-risk concern for aquatic plants, including algae, because they easily flow out from paddy fields into rivers, with toxic effects. The effect on algal population dynamics, including population recovery after timed exposure, must be assessed. Therefore, we demonstrated concentration-response relationships of four paddy herbicides for algal growth inhibition and mortality, and the relationship between the effect on algal cell viability and population recovery following exposure.

Quantitative analyses of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in fields with different soil types.

Soil type is one of the key factors affecting soil microbial communities. With regard to ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), however, it has not been determined how soil type affects their community size and soil nitrification activity. Here we quantitatively analyzed the ammonia monooxygenase genes (amoA) of these ammonia oxidizers in fields with three different soil types (Low-humic Andosol [LHA], Gray Lowland Soil [GLS], and Yellow Soil [YS]) under common cropping conditions, and assessed the relationships between soil nitrification activity and the abundance of each amoA.

Evaluation of the risk of mixtures of paddy insecticides and their transformation products to aquatic organisms in the Sakura River, Japan.

To assess the risk of mixtures of six paddy insecticides and their transformation products (TPs) to aquatic organisms in the Sakura River, Japan, their concentrations in the river water were monitored during the rice cultivation season in 2008 and 2009, and acute toxicity tests for Cheumatopsyche brevilineata (caddisflies) and Daphnia magna (daphnids), surrogate test species for caddisflies and cladocerans, respectively, were conducted. The mixture of fipronil, applied in the rice nursery box, and its desulfinyl, sulfide, and sulfone TPs were detected in the river for several months after transplanting, and they were more toxic to C. brevilineata than the other tested compounds.

Analytical evaluation of enzyme-linked immunosorbent assay for neonicotinoid dinotefuran for potential application to quick and simple screening method in rice samples.

The analytical performance of a kit-based enzyme-linked immunosorbent assay (ELISA) for the determination of a neonicotinoid insecticide dinotefuran residue in rice samples is addressed. The sensitivity (I(50) value) was 5.4 ng/mL, with the limit of detection, 0.

Transformation of diphenylarsinic acid in agricultural soils.

We investigated the transformation and fate of diphenylarsinic acid (DPAA) during incubation in two types of soils (Entisol and Andisol) under aerobic and anaerobic conditions. Under anaerobic conditions only, DPAA was transformed into methyldiphenylarsine oxide by methylation. Under both aerobic and anaerobic conditions, DPAA was degraded to phenylarsonic acid by dephenylation, and phenylarsonic acid was subsequently methylated to form methylphenylarsinic acid and dimethylphenylarsine oxide.

Risk assessment of non-target effects caused by releasing two exotic phytoseiid mites in Japan: can an indigenous phytoseiid mite become IG prey?

Two exotic phytoseiid mites, Neoseiulus cucumeris and Amblyseius swirskii, are commercially available in Japan for the control of thrips and other pest insects. As part of a risk assessment of the non-target effects of releasing these two species, we investigated intraguild predation (IGP) between these exotic phytoseiid mites and an indigenous phytoseiid mite Gynaeseius liturivorus, which is promising as an indigenous natural enemy for the control of thrips in Japan. To understand IGP relations between the exotic and indigenous phytoseiid mites after use of the exotic mites for biological control, we investigated IGP between them in the absence of their shared prey.

Arsenic release from flooded paddy soils is influenced by speciation, Eh, pH, and iron dissolution.

Arsenic (As) is highly mobilized when paddy soil is flooded, causing increased uptake of As by rice. We investigated factors controlling soil-to-solution partitioning of As under anaerobic conditions. Changes in As and iron (Fe) speciation due to flooded incubation of two paddy soils (soils A and B) were investigated by HPLC/ICP-MS and XANES.

Lack of cross-resistance to a novel succinate dehydrogenase inhibitor, fluopyram, in highly boscalid-resistant isolates of Corynespora cassiicola and Podosphaera xanthii.

Background: Recently in Japan, isolates resistant to boscalid, a succinate dehydrogenase inhibitor (SDHI), have been detected in Corynespora cassiicola (Burk. & Curt.) Wei and Podosphaera xanthii (Castaggne) Braun & Shishkoff, the pathogens causing Corynespora leaf spot and powdery mildew disease on cucumber, respectively.

Immunochromatography for the rapid determination of cadmium concentrations in wheat grain and eggplant.

Background: A simple and quick on-site test for trace levels of cadmium (Cd) in food is needed because of the human toxicity of this heavy metal. We developed an immunochromatography kit which uses the antigen-antibody complex reaction between the Cd-ethylenediaminetetraacetic acid (Cd-EDTA) complex and an anti-Cd-EDTA antibody. We previously reported the successful use of this kit to determine Cd concentrations in brown rice with respect to the international standard: 0.

Evaluation of methods of determining humic acids in nucleic acid samples for molecular biological analysis.

It is important in molecular biological analyses to evaluate contamination of co-extracted humic acids in DNA/RNA extracted from soil. We compared the sensitivity of various methods for measurement of humic acids, and influences of DNA/RNA and proteins on the measurement. Considering the results, we give suggestions as to choice of methods for measurement of humic acids in molecular biological analyses.

Rapid changes in δ¹³C of ecosystem-respired CO₂ after sunset are consistent with transient ¹³C enrichment of leaf respired CO₂.

The CO₂ respired by darkened, light-adapted, leaves is enriched in ¹³C during the first minutes, and this effect may be related to rapid changes in leaf respiratory biochemistry upon darkening. We hypothesized that this effect would be evident at the ecosystem scale. High temporal resolution measurements of the carbon isotope composition of ecosystem respiration were made over 28 diel periods in an abandoned temperate pasture, and were compared with leaf-level measurements at differing levels of pre-illumination.

Effects of arsenic compound amendment on arsenic speciation in rice grain.

Rice consumption is a major source of arsenic for Asian populations. Arsenic is present in rice grain both as inorganic arsenic and as dimethylarsinic acid (DMA). It is unclear whether DMA in rice is taken up from the soil or synthesized in planta.

Male killing and incomplete inheritance of a novel spiroplasma in the moth Ostrinia zaguliaevi.

Bacteria of the genus Spiroplasma are widely found in plants and arthropods. Some of the maternally transmitted Spiroplasma endosymbionts in arthropods are known to kill young male hosts (male killing). Here, we describe a new case of Spiroplasma-induced male killing in a moth, Ostrinia zaguliaevi.

Method for simple and rapid enumeration of total epiphytic bacteria in the washing solution of rice plants.

The phyllosphere is one of the most common habitats for terrestrial bacteria. However, little is known about the populations of bacteria, including unculturable bacteria, that thrive on plant surfaces. Here, we developed a fluorescent nuclear staining technique to easily and rapidly observe and enumerate populations of total and living epiphytic bacteria, with particular emphasis on the concentration by centrifugation and fixation of the epiphytic bacteria.

Hybridization between GM soybean (Glycine max (L.) Merr.) and wild soybean (Glycine soja Sieb. et Zucc.) under field conditions in Japan.

Accumulation of information about natural hybridization between GM soybean (Glycine max) and wild soybean (Glycine soja) is required for risk assessment evaluation and to establish biosafety regulations in Japan. This is particularly important in areas where wild relatives of cultivated soybean are grown (i.e.

Effect of Storage Temperature on Soil Nematode Community Structures as Revealed by PCR-DGGE.

The optimal duration and conditions for storage of soils collected for nematode community analyses are unknown. To study this issue, three types of soils with different geographical origins from the subarctic to cool-temperate Japan were kept at three temperature levels (5, 10, and 20(°)C) for up to 8 wk following collection. During the storage period, nematode population density was measured, and community structure was assessed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE).

Microarray analysis of Arabidopsis plants in response to allelochemical L-DOPA.

Velvetbean (Mucuna pruriens) plants impede the growth of neighboring plants. One compound, 3-(3',4'-dihydroxyphenyl)-L-alanine (L-DOPA), is responsible for the allelopathic capacity of velvetbean. This compound is an active allelochemical that decreases root growth of several plant species.

Carbon sources of natural cyanamide in Vicia villosa subsp. varia.

The ¹³C labels of [¹³C]carbon dioxide and D-[¹³C₆]glucose were incorporated into cyanamide (NH₂CN) when they were administered to Vicia villosa subsp. varia shoots. In contrast, the administration of sodium [2,3-¹³C₂]pyruvate did not affect the relative area of the [M + 1]+ ion of cyanamide in the gas chromatography-mass spectrometry analysis.