− 1 − ABSTRACT We investigated the growth and chlorophyll-related parameters of the marine diatom Skeletonema marinoi-dohrnii complex (NIES-324) exposed to tributyltin (TBT) or photosystem (PS) II inhibitor Irgarol as a reference chemical for elucidating the effect of TBT on photosynthetic activity. Fifty percent effective concentrations for growth (EC50) were 2.14 μg/L in TBT and 1.14 μg/L in Irgarol. Chlorophyll a content per one cell (pg/cell) was significantly decreased at the highest Irgarol concentration (1.0 μg/L) but chlorophyll c content was not affected. Following TBT treatment, however, both chlorophyll a and c content per cell increased significantly at the highest concentration (2.0 μg/L). The ratio of chlorophyll a and c content (chl. a/c ratio) decreased significantly and the minimum level of chlorophyll fluorescence (Fo) per μg/ mL of chlorophyll a (Fo/chl. a) increased significantly in all Irgarol treatment groups, but TBT had no effect on either parameter. The present results suggest that TBT has no direct effect on electron flow in the photosystem and that the chl. a/c ratio and Fo/chl. a are sensitive bio-markers for detecting the effect of the PSII inhibitor in diatoms.
1.緒言 カエルは,幼生(オタマジャクシ)が水生昆虫 等 の,成体がヘビ類 やサギ等鳥類 の主要 な餌となることから,水系及び周辺域の生態系の 多様性維持において重要な位置を占めるとされ, また,大量の昆虫類を補食することから土着天敵 としての活用 も模索されており,その保全が 求められている 。ニホンアマガエル(Hyla japonica)は日本全国に生息し,水田やその周辺 域で現在最も普遍的に見られるカエルである 。 水田を主な産卵場所とし,水田で農薬が使用され る 5 7 月に産卵して幼生(オタマジャクシ)の 時期を過ごすため,農薬等化学物質の影響を受け ることが懸念される。本種幼生に関しては,除草 剤のペンタクロロフェノールナトリウム塩(PCPNa)とベンチオカーブに対する感受性の測定例 ABSTRACT Sensitivity to several rice paddy pesticide formulations(4 nursery-box-applied insecticides and 7 herbicides)for the tadpoles of Japanese Tree Frog(Hyla japonica) was tested. LC50 values of 4 insecticides and 4 paddy herbicides for the tadpoles were high(> 100mg/L), however, those of 3 herbicides(Kirifuda one kilo granule, Boss one kilo granule and Sparkstar one kilo granule)were relatively low(10-30mg/L). In the active ingredients of the 3 herbicides, which showed high toxicity, LC50 values of indanofan, esprocarb, pretilachlor and dimethametryn were low(0.3-5mg/L). Concentration changes of these active ingredients in paddy water was calculated by the simulation model(PADDY), and the calculated maximum concentrations of indanofan, esprocarb, pretilachlor and dimethametryn were less than LC50 values of these active ingredients for the tadpoles. These results suggest that the tested rice paddy pesticides are less likely to influence to the Japanese Tree Frog’s tadpoles.
91 ABSTRACT Studies on the accumulation of waterborne nitrated polycyclic aromatic hydrocarbons (NPAHs), commonly known as nitroarenes, by fish are not well known. In this study, bioconcentration of NPAHs by marbled flounder, Pleuronectes yokohamae exposed to a mixture of six NPAHs was investigated in a continuous flow-through system for a period of seven days exposure followed immediately with seven days elimination. P. yokohamae is one of commercially important fish in Japan and is known to accumulate pollutants. Results show that NPAHs steady-state conditions were established from day 1 to 4 of exposure. Estimated bioconcentration factors(BCFs)ranged from 4 to 422 with 6-nitrochrysene and 2-nitrofluorene having the lowest and highest BCFs, respectively. Half-lives were from 0.96 to 5.59 days with 2-nitroflourene and 6-nitrochrysene being the shortest and the longest, respectively. The present study showed that waterborne NPAHs were accumulated by marbled flounder but the BCFs were lower than reported values of their parent PAHs. Furthermore, the difference in BCFs between NPAHs and PAHs could be attributed to the biotransformation processes and steric hindrance of these compounds.
Manufactured Nanomaterials （ MNs ） are excellent industrial materials that are not only widely used in the manufacture of displays, Micro Electro Mechanical Systems （ MEMS ） , composite materials, energy cells, fibers, actuators and heat-exchangers, but also in cosmetics, medical equipment and pharmaceutical products. Accordingly, the concerned regulating authorities are those involved in the control of chemicals for industrial use, drugs, food, the environment, scientific technology, as well as communications, etc. As of August 2012, however, no specific laws that regulate the safety evaluation of MNs exist. Each of the major MN producers, such as EU, the United States, and Japan, is separately going through the process of discussing the methodology of systematically evaluating and regulating MNs. The MN producers have started to organize independent consortiums or working groups to discuss the safety assessments of the products. In this context, we investigated the activities towards the setting of regulations in each country, and clarified the differences between their directions. We also introduce reference materials that have been published as a general scheme for safety evaluation.
