Japanese Journal of Environmental Toxicology
Online ISSN : 1882-5958
Print ISSN : 1344-0667
ISSN-L : 1344-0667
Volume 7, Issue 2
Displaying 1-9 of 9 articles from this issue
AWARD FOR ENCOURAGEMENT OF RESERACH
  • Narisato Hirai, Ayumi Nanba, Masaaki Koshio, Masatoshi Morita, Masatos ...
    2004 Volume 7 Issue 2 Pages 49-53
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    Sex transformed medaka exposed to 17β-estradiol (E2) in short-term exposure (egg-larva period) and long-term exposure (egg-adult period) was examined the reproductive character in fecundity, spawning times, and fertility. Most genetic males were transformed to phenotypic female by E2 in both exposure periods. On the other hand, reproductivity and GSI of sex-transformed female (XY female) in long-term exposure are lower than that of XY female in short-term exposure and of normal female (XX) in control. In gonad histology of XY females, those in short-term exposure possessed well-matured ovary as well as XX female in control. On the other hand, most XY females in long-term exposure possessed immature ovary, especially, most oocytes are in pre-vitellogenic phase. From these results, it is considered that the exposure to E2 until the end of larval period induce the sex-transformed medaka with high reproductivity as well as XX female in control, but suggesting that the longer exposure to E2 might inhibit to sexual maturation in XY female.
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  • Shusaku Hirakawa, Hisato Iwata, Eun-Young Kim, Shinsuke Tanabe, Nobuyu ...
    2004 Volume 7 Issue 2 Pages 55-59
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    Baikal seal (Pusa sibirica) accumulates high levels of environmental contaminants such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs). In mammalian species, the toxic effects of these chemicals are posed by the modulation of transactivation of multiple target genes including cytochrome P450 (CYP) 1A1 and 1A2 mediated by the aryl hydrocarbon receptor. In order to clarify whether CYP1A1 and CYP1A2 are induced by these dioxin-like congeners in wild Baikal seals, this study attempted to identify these CYP cDNAs and to analyze relationships between the hepatic concentrations of PCDDs/DFs/Co-PCBs and CYP1A1/1A2 mRNA expression levels in the seal population. The full-length CYP1A1 and 1A2 cDNAs were isolated from the liver of Baikal seal. CYP1A1 cDNA encoded 517 amino acid residues with a predicted molecular mass of 58.3 kDa, and CYP1A2 cDNA encoded 512 amino acid residues with a predicted molecular mass of 57.8 kDa. Both CYP1A1 and 1A2 mRNA levels showed significant positive correlations with total TEQs and the majority of individual congener TEQs. Lower correlations were found for 2,3,7,8-T4CDD/DF, O8CDD, PCB77, PCB169, and mono-ortho Co-PCB congeners. This indicated preferential metabolism of 2,3,7,8-T4CDD/DF and PCB77 by induced CYP1A1/1A2, and lower CYP induction potentials as for other congeners. The mRNA levels of CYP1A1/1A2 revealed significant positive correlations with CYP1A-like protein levels, which were immunochemically detected by anti-rat CYP1A1 polyclonal antibody, suggesting that the CYP1A-like protein levels reflect both CYP1A1 and CYP1A2 mRNA levels. These results revealed that both CYP1A1 and 1A2 are induced by PCDDs/DFs/Co-PCBs at transcriptional and translational levels in the liver of Baikal seals.
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ARTICLES
  • Yuji Oshima, Tatsusuke Takeda, Sachie Katayama, Yoshiyuki Inoue, Sugur ...
    2004 Volume 7 Issue 2 Pages 61-68
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    We evaluated the relation between oxygen consumption rate (MO2), which correlates with water temperature and pharmacokinetic parameters of florfenicol (FFC) in carp (Cyprinus carpio). We administered FFC (dose, 10 mg/kg) intravascularly or orally to fish at 8, 14, 18, and 23°C. Blood was intermittently sampled via cannulae for 170 h, and the concentration of FFC in the serum was measured. We also determined the (MO2) at each temperature. Data were analyzed using a 1-compartment pharmacokinetic model, and absorption (ka) and elimination (ke) rate constants were estimated. We found that both ka and ke varied exponentially with (MO2) (r = 0.92 and 0.93 respectively) and with temperature (r = 0.91 and 0.94 respectively). These findings clearly demonstrate that the rates of absorption and elimination of FFC in carp decrease as (MO2) and water temperature drop.
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  • Jianqiang ZHANG, Izumi WATANABE, Hirokazu Ozaki, Katsuji KUNO
    2004 Volume 7 Issue 2 Pages 69-80
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    Tolerance of various plants to Cr was studied at the following different Cr6+ concentrations of water cultural solutions: 0.0, 0.5, 2.0, 8.0 mg l-1 (w/v). The plants used for the trials were Oryza sativa L., Phaseolus vulgaris L., Morus bombycis Koidz, Brassica oleracea var. captata L., Glycine max (L.) Merr., Brassica campestris L.var. pervirdis. The cultivation was designed for 10 days of operation to measure the dry weight growth (dry increment) of the plants and the concentration change of Cr in plant tissues. Growth analysis has been used to analyze the tolerance of plant toward Cr. The plants were categorized into three types based on their Cr tolerance through the measurement of dry weight growth (dry increment), relative growth rate (RGR), net assimilation rate (NAR) and leaf dry weight ratios (LWR) of the plants before, during and after the cultivation. High tolerance plants were Oryza sativa L. and Phaseolus vulgaris L.; medium tolerance plants were Morus bombycis Koidz. and Brassica oleracea var. captata L.; and the low or poor tolerance plants were Glycine max (L.) Merr. And Brassica campestris L.var. pervirdis.
    Increase of Cr concentration added to various plants was linear to the dry weight growth, relative growth rate and net assimilation rate. The Cr concentration of the upper parts of plants above the soil and the Cr transferring rate to those parts dominated the Cr tolerance of a plant. This because the increase of the Cr concentration of the upper parts of plants above the soil and the Cr transferring rate to those parts can inhibit or interfere the physiological functioning a plant, which results in the decrease of organic assimilation capacity or photosynthesis function of the plant, measuring as the decreases of chlorophyll contents, dry weight growth, relative growth rate and net assimilation rate.
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  • Akira KAKUNO, Jiro KOYAMA
    2004 Volume 7 Issue 2 Pages 81-95
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    Hematological analysis for evaluating sublethal toxicity of chemicals is highly developed and reliable in mammalian studies, but the principles and methods have been only partially extended to fish. Therefore, in order to confirm the usefulness of the hematological approach to estimate toxicity of chemicals for fish, we determined the hematological parameters in red sea bream, Pagrus major. Fish were exposed to sublethal concentrations of bis(tributyltin) oxide (TBTO: 0.031, 0.112, 0.52, 1.98, 0.66, or 1.59 μgTBT/L), triphenyltin chloride (TPTC: 0.13, 1.16, or 3.23 μg/L), naphthalene (0.06, 0.21, 0.8, or 2.42 mg/L), and cadmium chloride (Cd: 0.01, 0.06, or 0.37 mg/L) for 8 or 9 weeks. The lowest observed effect concentrations (LOECs) and the no observed effect concentrations (NOECs) of pollutants were determined from red blood cell count, hematocrit (Ht), or hemoglobin concentration. LOECs and NOECs of TBTO, TPTC, naphthalene and Cd determined by Ht were 0.52μg/L and 0.112μg/L, 3.23μg/L and 1.16μg/L, 0.80mg/L and 0.21mg/L, and 0.37mg/L and 0.06mg/L, respectively. These values were similar to the LOEC and the NOEC determined by the growth parameters, which were reported previously. Additionally, Ht was the most sensitive parameter among the hematological parameters described above. These results suggest that hematological parameter, especially Ht, was a very useful parameter to estimate chronic toxicity of chemicals for fish.
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  • Yoshio Sugaya
    2004 Volume 7 Issue 2 Pages 97-104
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    Susceptibility of populations of the midge Chironomus yoshimatsui (Diptera: Chironomidae) to fenitrothion was investigated at 32 sites. Resistance (48h-LC50>1,000 μg/l) to the insecticide was found in populations on 23 sites, nine of which had no records of fenitrothion use. Susceptible populations (ranging from 6.7 to 17.7 μg/l of the 48h-LC50) were found on 6 of 9 sites in Hokkaido, but only two of 23 sites in other districts. However, a susceptible population was found in Yumoto, while the population in Tokorono (30 km from Yumoto) where there are neighboring rice fields, comprised both susceptible and resistant individuals; no susceptible individuals were found in Honshu districts, except for Yumoto and Shirahone.
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  • Osamu Saika, Yoko Kohayakawa, Yoshinobu Fujii, Akihiko Hara
    2004 Volume 7 Issue 2 Pages 105-112
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    The acute toxicity of 3 metal irons, copper (II) , chromium (IV) and zinc (II) and the long-term toxicity (21-day exposure) of copper were evaluated in both male and female Daphnia magna (Cladocera, Branchiopoda) to investigate sex differences. Prior to toxicity tests, environmental conditions, in which daphnids produced male neonates at a higher ratio and with predictable timing, were examined and a practical method to obtain males was determined. Male and female neonates were obtained from female parents exposed to a shorter photoperiod and reduced food supply, and were used for the acute and long-term toxicity tests. There was no significant difference between the male and female 48hr- EC50 values in the acute toxicity test or mortality, fecundity or growth parameters in the long-term toxicity test. It is therefore considered that there is no large sex difference in the acute toxicity of copper, chromium, zinc and in the long-term toxicity of copper.
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  • Hidehiro Kaneko, Masato Yoshikawa, Keiko Katayama-Hirayama, Kimiaki Hi ...
    2004 Volume 7 Issue 2 Pages 113-121
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    A rapid toxicity test based on the movement of the trunk limbs of Daphnia was developed using Daphnia pulex. A decrease in the frequency of the trunk limb movement by exposure to toxicants was measured. In developing the test method, the effects of food condition, body size, temperature management and exposure period on the movement of the trunk limbs were examined. The food condition did not affect the frequency of the trunk limb movement, provided that the Daphnia were removed from the breeding vessel after one or two days from feeding. Although the frequency tended to slightly decrease with the increase in body size, the ratio of the frequency after and before testing was not affected by the body size. Controlling the temperature at 20°C was helpful for improving the reproducibility. Considering the labor to manually count the trunk limb movements, the test period was 3 hours. Although this test was less sensitive than the Daphnia Immobilization Test, it was considered that this test may possibly be used to evaluate the ecotoxicity of wastewater and/or solid waste as a screening test.
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  • Yuji Oshima, Jiro Koyama, Kei Nakayama, Yoshiyuki Inoue, Yohei Shimasa ...
    2004 Volume 7 Issue 2 Pages 123-129
    Published: 2004
    Released on J-STAGE: July 01, 2010
    JOURNAL FREE ACCESS
    Cytochrome P4501A activities (measured as ethoxyresorufin-O-deethylase (EROD)) in the liver of flounder, Paralichthys olivaceus, were measured as a biomarker of the response to dispersed oil exposure. EROD activities in flounder administered crude oil (0.1, 0.3 and 1 mg/kg body weight/day) in their diets increased to more than 20-fold of those in control fish. The increased activities persisted for 6 days after cessation of exposure to heavy oil. These results demonstrated that EROD in the liver of Japanese flounder is a good biomarker of oil pollution. However, no significant increase in EROD activity was observed in flounder collected from Nakhodka oil spill areas compared with those collected from control sites.
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