In vitro evaluation of atmospheric particulate matter and sedimentation particles using yeast bioassay system.

Little information on the evaluation of airborne particulate matter (APM) and sedimentation particles from subway stations is available. The thermal metamorphism of train wheels generating toxic particles in subway stations is a possibility. In this study, the toxicity and physiological effects of particles from subway stations were evaluated using a yeast bioassay system. Estrogenic and antiestrogenic activities of APM in APM extracts from subway stations were determined. No estrogenic activity was found in the APM fractions and their S9-activated APM samples. Sedimentation dust samples also showed no estrogen activity. In contrast, extracts from sedimentation dust samples showed antiestrogen activity. Marked yeast toxicity was observed in the samples extracted from sedimentation dust. Potent yeast toxicity was also found in the S9-activated extracts from sedimentation dust. The results suggest that sedimentation dust from a semiclosed area of a subway system has antiestrogen activity, although both the origin and generation system of this activity are uncertain. These pollutants in sedimentation dust may change to a more toxic form in vivo by S9 activation.

Effect of estrogenic activity, and phytoestrogen and organochlorine pesticide contents in an experimental fish diet on reproduction and hepatic vitellogenin production in medaka (Oryzias latipes).

Endocrine-disrupting chemicals (EDCs) are giving rise to serious concerns for humans and wildlife. Phytoestrogens, such as daidzein and genistein in plants, and organochlorine pesticides are suspected EDCs, because their chemical structure is similar to that of natural or synthetic estrogens and they have estrogenic activity in vitro and in vivo. We assessed estrogenic activity and dietary phytoestrogen and organochlorine pesticide contents of various fish diets made in the United Kingdom, and compared them with those features of diets made in Japan that were tested in a previous study. Genistein and daidzein were detected in all of the diets. Using an in vitro bioassay, many of these diets had higher activation of estrogen beta-receptors than estrogen alpha-receptors. Organochlorine pesticides such as hexachlorobenzene, beta-benzene hexachloride (BHC), and gamma-BHC were detected in all fish diets. On the basis of these data, we investigated the effect of differing dietary phytoestrogen content in Japanese fish diets on hepatic vitellogenin production and reproduction (fecundity and fertility) in medaka (Oryzias latipes). Assessment of the effects of a 28-day feeding period on reproduction of paired medaka did not indicate significant differences in the number of eggs produced and fertility among all feeding groups. However, hepatic vitellogenin values were significantly higher for male medaka fed diet C (genistein, 58.5 +/- 0.6 microg/g; daidzein, 37.3 +/- 0.2 microg/g) for 28 days compared with those fed diet A (genistein, < 0.8 microg/g; daidzein, < 0.8 microg/g) or diet B (genistein, 1.4 +/- 0.1 microg/g; daidzein, 2.0 +/- 0.1 microg/g). Our findings indicate that fish diets containing high amounts of phytoestrogens, such as diet C, have the potential to induce hepatic vitellogenin production in male medaka, even if reproductive parameters are unaffected. Therefore, some diets, by affecting vitellogenin production in males, may alter estrogenic activity of in vivo tests designed to determine activity of test compounds added to the diet.

Self-assembling of the porphyrin-linked acyclic penta- and heptapeptides in aqueous trifluoroethanol.

The conjugates of porphyrin with links to the acyclic penta- and heptapeptides were synthesized to mimic natural multiple porphyrin systems. The linear penta- and heptapeptide with hydrophilic/hydrophobic alternative sequences took a random structure in aqueous trifluoroethanol (TFE). However, these polypeptides took a beta-sheet structure in the same solvent when the N-terminal Cys linked to the porphyrin, suggesting that the conjugates self-assembled via the intermolecular hydrophobic interaction between the porphyrins. The circular dichroism (CD) spectra, UV/vis spectra, size exclusion chromatography (SEC), and (1)H NMR spectroscopy supported the self-assembling. In the self-assembled structure of the pentapeptide linking porphyrin at the p-phenyl position (9), the porphyrins were involved in two porphyrin-porphyrin interactions, i.e., the side-by-side interaction between the neighboring polypeptide chains and the face-to-face interaction between the first and the third peptide chains. The CD spectra of 9 showed two sets of Cotton effects probably arising from these two interactions. The UV/vis spectra also supported the above interpretation, showing multiple absorptions in the longwave and shortwave shifted regions. The SEC analyses showed the assembled structure of the conjugates. The (1)H NMR signals of the porphyrin rings of 9 were hardly observed in D(2)O-CD(3)OD because of the shortened spin-spin relaxation time T(2)().