Livers of LEC rats were histochemically stained for copper according to the modified Timm's method, which includes trichloroacetic acid (TCA) treatment. TCA pretreatment was effective in removing zinc and iron, leaving as the major metal in the liver. Hepatocytes in 3-month-old rats were stained intensely by the modified Timm's method, both in frozen sections and in paraffin-embedded specimens. The centrilobular hepatocytes were usually stained, but positive cells were also randomly distributed in the hepatic lobes, showing a mosaic pattern. The staining was intensified in 8- compared to 3-month-old LEC rats. In contrast hepatocytes from LEA rats, the normal counterpart of LEC rats, were faintly stained for copper. Proliferating cholangioles found in older LEC rats were shown to lack copper deposition, and hepatocellular carcinoma showed less copper deposits than the hepatocytes surrounding the tumor. The copper staining was augmented in livers of LEC rats subjected to copper-loading, but was less intense in the livers treated with D-penicillamine. The staining intensity under the various experimental conditions showed good correlation with the copper concentration. Lysosomal deposition of copper in hepatocytes was demonstrated by electron microscopic analysis for copper. Thus the modified Timm's method was shown to produce valuable results in demonstrating copper in LEC rat livers, providing important information for an understanding of the mechanism of copper deposition and hepatic disease of the animal.

Frequency-dependent selection is a fundamental principle of adaptive sex ratio evolution in all sex ratio theories but has rarely been detected in the wild. Through long-term censuses, we confirmed large fluctuations in the population sex ratio of the aphid Prociphilus oriens and detected frequency-dependent selection acting on these fluctuations. Fluctuations in the population sex ratio were partly attributable to climatic factors during the growing season. Climatic factors likely affected the growth conditions of host plants, which in turn led to yearly fluctuations in maternal conditions and sex ratios. In the process of frequency-dependent selection, female proportion higher or lower than ca. 60% was associated with a reduction or increase in female proportion, respectively, the next year. The rearing of aphid clones in the laboratory indicated that mothers of each clone produced an increasing number of females as maternal size increased. However, the mean male number was not related to maternal size, but varied largely among clones. Given genetic variance in the ability to produce males among clones, selection should favour clones that can produce more numerous males in years with a high female proportion. Population-level sex allocation to females was on average 71%-73% for three localities and more female-biased when maternal conditions were better. This tendency was accounted for by the hypothesis of competition among foundresses rather than the hypothesis of local mate competition. We conclude that despite consistent operation of frequency-dependent selection, the sex ratio continues to fluctuate because environmental conditions always push it away from equilibrium.

New Bromine-Containing Unsaturated Fatty Acid Derivatives from the Okinawan Marine Sponge Xestospongia sp.-17 Title acids of type (I)-(IV) are isolated.-(LI, Y.; ISHIBASHI, M.; SASAKI, T.; KOBAYASHI, J.; J.

Formation and Breakdown of Anodic Oxide Films on Aluminum in Boric Acid/Borate Solutions.-The effect of borate concentration on the formation and breakdown of anodic films on Al at a current density of 25 A/m2 at 293 K is studied in 0.5 M H3BO3/0, 0.005, or 0.05 M Na2B4O7·10H2O solutions by ICP-AES, EL, PL, FE-SEM, TEM, and EIS. Differences in the film formation and breakdown between boric acid/borate and boric acid solutions are discussed in terms of the pH-buffering ability of the solutions. The electronic structure of the anodic oxide films is correlated with the electroand photoluminescence spectra. -(LI, Y.; SHIMADA, H.; SAKAIRI, M.; SHIGYO, K.; TAKAHASHI, H.; SEO, M.; J.

The structures of the title compounds (I)-(III), which are isolated together with nine known taxoids, are confirmed by spectroscopic means and photochemical synthesis. They increase vincristine accumulation in multidrug-resistant tumor cells and show weak cytotoxicity. (II) also reduces CaCl2-induced depolymerization of microtubules. -(KOBAYASHI, J.; OGIWARA, A.; HOSOYAMA, H.; SHIGEMORI, H.; YOSHIDA, N.; SASAKI, T.; LI, Y.; IWASAKI, S.; NAITO, M.; TSURUO, T.; Tetrahedron 50 (1994) 25, 7401-7416; Fac. Pharm. Sci., Hokkaido Univ., Sapporo 060, Japan; EN)