Previously, as a new type of pH-sensitive liposome, we prepared egg yolk phosphatidylcholine (EYPC) liposomes bearing succinylated poly(glycidol), that is a poly(ethylene glycol) derivative having carboxyl groups, and showed that fusion ability of the liposomes increases under weakly acidic and acidic conditions (Kono, K., Zenitani, K. and Takagishi, T. (1994) Biochim. Biophys. Acta 1193, 1-9). In this study, we examined intracellular delivery of a water-soluble molecule, calcein, mediated by the succinylated poly(glycidol)-modified liposomes. When CV-1 cells, an established line of African green monkey kidney cells, were incubated with bare EYPC liposomes containing calcein at 37 degrees C, only weak and vesicular fluorescence of calcein was observed by using a fluorescence microscope. In contrast, the cells treated with the polymer-modified liposomes containing calcein displayed more intensive and diffuse fluorescence, indicating that calcein was transferred into the cytoplasm. Uptake of the polymer-modified liposomes by the cells was shown to decrease slightly as amount of the polymer fixed on the liposome increases. However, the fluorescence of calcein observed in the liposome-treated cell was, on the contrary, enhanced as amount of the polymer fixed on the liposome increases, indicating that the liposome modified with a higher amount of the polymer transfers its content into cytoplasm more efficiently after internalization into the cell. Fusion assay by resonance energy transfer using N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)phosphatidylethanolamine and lissamine rhodamine B-sulfonylphosphatidylethanolamine suggested occurrence of fusion between the polymer-modified liposomes and endosomal and/or lysosomal membranes. Moreover, the liposome with a higher polymer content revealed higher percent fusion after internalization into the cell. These results imply that the polymer-modified liposomes transfer the content into the cytoplasm by fusing with the endosomal membrane after internalization into the cells through an endocytic pathway.
A survey on seasonal concentration changes of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was performed for surface water in Lake Biwa (14 sites) from February to November in 2009. The concentrations of PFOS and PFOA were 0.8-1.6 and 7.0-10 ng/L in northern basin of Lake Biwa (eight sites), 0.9-1.7 and 8.3-13 ng/L in southern basin of Lake Biwa except Akanoi Bay (four sites), 1.4-2.8 and 9.1-17 ng/L in Akanoi Bay (8C) and 2.4-5.3 and 12-26 ng/L in Akanoi Bay (168), respectively. Seasonal changes were recognized for both of PFOS and PFOA in the two sites of Akanoi Bay but not in the other sites of the southern and northern basins of Lake Biwa. Monthly detailed surveys in the surface water were performed on the changes of PFOS and PFOA concentrations from June in 2009 to May in 2010 and further on the changes of conductivity values. The changes of PFOS and PFOA concentrations were well consistent with those of conductivity values.
A survey of various pesticide contaminations was performed for water in Yanamune River flowing into Lake Biwa from 1988 to 2009. Ten pesticides (diazinon and fenitrothion as insecticides, iprobenfos and isoprothiolane as fungicides and chlornitrofen, thiobencarb, molinate, bromobutide, simetryne and pretilachlor as herbicides) were selected and concentration changes of the pesticides were evaluated based on their shipment amounts. Yearly maximum concentrations of eight of the pesticides in Yanamune River water were compared with their no observed effect concentration and their predicted no effect concentration values and initial ecological risk assessment was conducted for five pesticides (diazinon, fenitrothion, iprobenfos, isoprothiolane and thiobencarb) by their predicted no effect concentration values. All of the diazinon (0.01-0.28 μg/L) and fenitrothion (0.005-0.31 μg/L) concentrations from 1988 to 2007, the iprobenfos (2.7 and 2.4 μg/L) concentrations in 1988 and 1990 and the thiobencarb (0.24-2.7 μg/L) concentrations in 1988, 1992, 1993 and 1995 exceeded their predicted no effect concentration (PNEC) (0.00026, 0.00021, 1.0 and 0.17 μg/L) values.
Summar yConcentrations of 10 perfluorinated compounds in water and fish from rivers and lakes in the world were reviewed from the surveys in the years of 1998-2011. A yearly decreasing tendency was recognized in the concentrations of Perfluorooctane sulfonate (PFOS) and Perfluorooctanoic acid (PFOA) in water from several rivers in Japan. The concentrations of PFOA in water from rivers and lakes in Japan had a tendency to be higher than those of PFOS but the concentration levels of both compounds were equal in Europe. Further, the concentrations of PFOS in water from rivers in Europe and North America were higher than those in Japan and Asia. Composition of the perfluorinated compounds was PFOA >> Perfluorononanoic acid (PFNA) ≧ Perfluorohexanoic acid (PFHxA) in water from rivers and lakes in Japan and PFOS ≧ PFOA in Asia, Europe and North America. Perfluorinated compounds with more carbon atoms were more highly accumulated in fish, and bioconcentration factor (BCF) of PFOS was lower than that of Perfluorododecanoic acid (PFDDA) and nearly equal to that of Perfluoroundecanoic acid (PFUA) or Perflurorodecanoic acid (PFDA). Each of the BCF data of the perfluorinated compounds by field survey data (Field BCF) was nearly in the same order as each of the BCF data by laboratory experimental data (Laboratory BCF). However, absolute values of the Field BCF had a tendency to be higher than those of the Laboratory BCF. To verify this tendency, it is necessary to accumulate additional data on Laboratory and Field BCF and to advance the research development in future on adding the uptake of the compounds via food for the uptake of the compounds via gill in the Field BCF values or on the differences of the environmental conditions. 以外は PFOA が PFOS より高い濃度を示し,滋賀県の琵琶湖(Lake Biwa) , 福井県の北潟湖 (Lake Kitagata) および岡山県の児島湖 (Lake Vol.22, No.4(2012) Vol.22, No.4(2012) Vol.22, No.4(2012) Vol.22, No.4(2012) Vol.22, No.4(2012) 世界河川および湖沼生息魚類における PFC 組成 比率 世界河川および湖沼生息魚類における有機フッ 素化合物の濃縮性および汚染評価炭素数 6,8,10,11 および 12 の有機フッ素化合物について,魚 類の実験データによる BCF 値 118-120)を湿重量単位で Table 3 Vol.22, No.4(2012) 20000(PFUA)および 100000(PFDDA,いずれも European chub Detection of perfluorooctane surfactants in Great Lakes water.Environ. Sci. Technol., 38, 4064-4070 (2004) Environ. Sci. Technol., 44, 2549-2554 114) Malinsky, M.D., Jacoby, C.B. and Reagen, W.K.: Determination ─ 173 ─ 環境化学 Vol.22, No.4(2012) 118) Martin, J.W., Mabury, S.A., Solomon, K.R. and Muir, D.C.G.:Bioconcentration and tissue distributionof perfluorinated acids in raibow trout (Oncorhynchus mykiss). Environ. Toxicol. Chem., 22, 196-204 (2003)
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