Gas chromatography�Cmass spectrometry for metabolite profiling of Japanese medaka (Oryzias latipes) juveniles exposed to malathion

Purpose

We evaluate malathion toxicity to Japanese medaka (Oryzias latipes) juveniles by using a mass spectrometry combined with gas chromatography (GC/MS) metabolomics approach.

Methods

Medaka were exposed to low (L) and high (H) concentrations (nominally 20 and 2,000 ??g/L, respectively) of water-borne malathion. Metabolites were extracted from the fish, derivatized, and analyzed by GC/MS. Identified metabolites were subjected to one-way analysis of variance and principal component analysis (PCA). We examined the variations in the amounts of the metabolites during the exposure period.

Results and discussion

At 24 h, control, L, and H groups were separated along PC1, suggesting that the effects of malathion depended on exposure concentration. The PCA results at 96 h suggest that the metabolite profiles variations of the L and H groups differed, and thus that the effects of malathion in groups differed. At 24 h, the amounts of amino acids in both exposed groups were lower than the control group amounts, perhaps owing to accelerated protein synthesis. At 96 h, the amounts of almost all the amino acids increased in the L group but decreased in the H group relative to the control group amounts, suggesting the proteolysis occurred in the L group while protein synthesis continued in the H group, that the high malathion exposure affected the fish. In addition, at 96 h, gluconeogenesis may have been induced in the L group but not in H group.

Conclusions

Malathion exposure may have altered the balance between protein synthesis and degradation and induced gluconeogenesis in medaka. Our results suggest that metabolomics will be useful for comprehensive evaluation of toxicity.     

Economic analysis of gradual “social exhaustion” of waste management capacity

This article proposes to analyze the quantitative effects of a gradual physical and “social” exhaustion of a landfill site on an equilibrium waste management service. A gradual social exhaustion of a landfill is defined here as an upward shift of a “subjective factor” associated with the amount of waste, based on the plausible hypothesis that an individual will not accept excessive presence of landfilled waste. Physical exhaustion occurs when the absolute capacity of a landfill site decreases. The paper shows some numerical examples using specific functions and parameters, and proposes appropriate directions for three policy objectives: to decrease the equilibrium waste disposal, to increase the economic surplus of the individual and/or the waste management firm, and to lower the equilibrium collection fee.     

Cetacean DNA fingerprinting using the oligonucleotide (GGAT)4 as a probe

Since the discovery in 1985 of hypervariable minisatellite regions in human DNA, DNA fingerprinting has been widely used in animals and plants. Although many different probes have been developed recently, most investigators still use 33.15 and 33.6 human polycore minisatellites for hybridization studies of cetaceans. This animal order shows considerably less variability than humans, and thus some limitations have to be taken into account when using these probes. The present study demonstrates that the short repetitive tandem oligonucleotide (GGAT)₄ hybridizes with cetacean (Globicephala macrorhynchus andGrampus griseus) DNA, yielding individual-specific patterns of bands or DNA fingerprints. Freedom of design and shorter hybridization times of oligonucleotides allow an increase in the number of usable probes used, helping to overcome some of the problems found when only human polycore minisatellites are used.     

Modern energy region development and income distribution: An input-output analysis

This paper formulates an input-output method for determining the distributional consequences of energy development projects. The method is oriented to the conditions appearing in many contemporary development settings where large resident populations and other factors are likely to inhibit boomtown scenarios. An analysis of geothermal energy development in Imperial County, California, is presented. The results indicate that personal income inequality is likely to increase by several percentage points as measured by the Gini coefficient. The sensitivity of the results is examined with respect to important factors such as labor supply elasticities, preferential employment of local residents, and the concentration of land holdings.     

Perfluorinated compounds in whole fish homogenates from the Ohio, Missouri, and Upper Mississippi Rivers, USA

A method for the analysis of 10 perfluorinated compounds (PFCs) in whole fish homogenate is presented and applied to 60 fish samples collected from the Ohio, Missouri, and upper Mississippi Rivers in 2005. Method accuracy ranged between 86 and 125% with limits of quantitation between 0.2 and 10 ng/g wet weight. Intra- and inter-batch precision was generally ±20%. Perfluorooctane sulfonate (PFOS) was the predominant compound identified in these samples, contributing over 80% of total PFC composition in the fish from these rivers, with median PFOS concentrations of 24.4, 31.8, and 53.9 ng/g wet wt in the Missouri, Ohio, and Mississippi Rivers, respectively. Median PFOS levels were significantly (p = 0.01) elevated in piscivorous fish (88.0 ng/g) when compared with non-piscivorous fish (15.9 ng/g). The 10 samples with PFOS concentrations above 200 ng/g were broadly scattered across all three rivers, providing evidence of the widespread presence of this compound in these US waterways.