No abstract

T he last half-century has seen momentous and accelerating changes in humankind's economic activities, political relations, and social and demographic profile. A prominent feature of this change is the increasing scale of human impact on Earth's natural biophysical systems: the climate system, stratospheric

Sockeye salmon (Oncorhynchus nerka) were followed during their 1400-km-long migration from cessation of feeding outside British Columbia, Canada, up the Fraser River to spawning. Enzymatic capacity (indicative of glycolysis, β-oxidation, and respiratory chain ATP formation), muscle fibre size distribution, body and muscle conformation, and gross chemical composition in different parts of red and white muscle were monitored to determine energy strategies throughout the migration. The mobilization of extramuscular lipid depots was also monitored. The most conspicuous change in white muscle, concomitant with a large decrease in protein content, was an ordered reduction in muscle fibre size and lipid depots with distance covered, resulting in an accumulation of fibres with a cross section between 2000 and 6000 µm2 and a maintained level of 4% intramuscular fat. A peak in oxidative capacity was noted in red muscle during the strenuous passage of Fraser Canyon. In white muscle, glycolytic capacity was maintained at least until passage of the Fraser Canyon. Enzymatic capacity was higher in the caudal than rostral part of the muscle. Differences were also found between lateral and dorsal parts of the white muscle, indicating significant differences in the timing and magnitude of enzymatic capacity of red and white muscle.

Cells exposed to UV light are not able to induce DNA synthesis in allogeneic cells. HL-A typing before and after irradiation gives identical results. It is suggested that active cell metabolism and not only disparity of cell surface antigens is necessary to provoke the mixed leucocyte culture reaction.

Fluoranthene (FA) was studied with respect to possible mechanisms of its high mutagenicity but low carcinogenicity, in comparison with the corresponding properties of benzo[a]pyrene (BaP), and with regard to the synergism of these two compounds shown by van Duuren and Goldschmidt (J Natl Cancer Inst 56, 1976, 1237). FA and BaP activated by S9 from Aroclor 1254 (PCB)-treated rats induce HPRT mutations in CHO cells with about equal effectiveness at the same exposure doses, which also lead to the same frequencies of repairable DNA adducts, enzyme-induced strand breaks being used as an indirect measure of adducts to DNA. FA was also shown to be an efficient inducer of SCE in human peripheral lymphocytes cocultivated with PCB-treated HepG2 cells or with liver cells from PCB-pretreated rats. For the induction of SCE, FA and BaP were shown to act additively. From metabolic studies with liver microsomes from C57Bl/6 mice it is concluded that, whereas BaP induces the metabolism of BaP to the mutagenic epoxide, neither BaP nor FA is able to induce the metabolism of FA. In mutation experiments with V79 cells (XEM2) constitutive for P450 IA1 activity, BaP 7,8-diol but not FA 2,3-diol provokes a high frequency of HPRT mutations. In cells constitutive for P450 IA2 enzymatic activity FA and BaP are but weakly mutagenic and practically nonmutagenic, respectively. Due to the additivity of the genotoxic effects of FA and BaP, induction of an error-prone condition by the latter compound seems to be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)