Marker and function analysis of natural killer and alloreactive T cells during early stages of dimethylbenzanthracene carcinogenesis. The immunity system during the precancer period

The effect of the chemical carcinogen dimethylbenzanthracene (DMBA) on cellular immunity was studied at a 6-mg dose which induces adenocarcinomas and adenoacanthomas in more than 70% of BalB/c mice within 1 year after administration. DMBA caused a significant reduction of splenic natural killer (NK) activity and responsiveness to alloantigens in mixed lymphocyte reactions (MLR). These activities decreased soon after the carcinogen treatment and remained suppressed during the entire tumor induction period. There was a linear correlation between the reduction in NK activity and a selective decrease in the number of asialo GM1 positive cells in the spleen. However, cell sorting experiments using the flow cytometer have shown that the lytic activity per cell of asialo GM-1 positive cells in untreated mice and in DMBA-treated ones was similar. There was no correlation between the suppressed response of the T cells in MLR and the percentage of T cell subpopulations residing in the spleen of the DMBA-treated mice. The decrease in the number of NK cells and the reduced MLR activity in the spleen occurred simultaneously with a decrease in the potential of bone marrow precursor cells to reconstitute NK and MLR activity in the spleen of lethally irradiated mice. These results indicate that the carcinogen DMBA effects the immune system at various levels and either eliminates or inactivates precursor cells as well as mature lymphoid cells.     

The structure and genetics of a montane population of the checkerspot butterfly,Chlosyne palla

Summary The population structure, genetics and ecology of the checkerspot butterfly, Chlosyne palla, in an area of Gunnison County, Colorado were investigated. The population structure was found to be quite different from that of most butterflies and from all of those aspects known for its thoroughly studied relative, Euphydryas editha. The population unit of Chlosyne palla may cover an area some five to eight times the size of the largest known Euphydryas population and twice the size of an Erebia epipsodea population in the same county of Colorado.Genetic variation at eleven loci of Chlosyne palla was examined by electrophoresis. Three samples of Chlosyne palla separated by 1.6, 4.7, and 12.0 km were not significantly different. Comparison with Euphydryas editha yields a genetic similarity of 0.186, about the same level as found by Ayala (1975) for different genera of Drosophila. Euphydryas editha from the same Colorado location were more similar to California E. editha than to C. palla, showing concordance with the phenetic classification. Decreased heterozygosity was observed for the Colorado E. editha and C. palla compared to California populations of E. editha and E. chalcedona.     

Infants' exploration of scented toys: effects of prior experiences

To evaluate breastfed infants' responses to scented objects, we videotaped the facial and bodily reactions of sixty-three infants as they explored, in succession, three toys that were identical in appearance but different in their characteristic odor. Two of the toys were scented with odorants previously shown to be transmitted to human milk, one with ethanol and the other with vanilla, whereas the third toy was unscented. Each videotape was subjected to frame-by-frame analysis to measure a variety of behaviors that are considered either to be exploratory in nature in that they lead to perceptual information about the object or to reflect the infants' hedonic reaction. Analyses of these behaviors revealed that the infants looked more and vocalized less in the presence of the vanilla-scented toy and spent less time manipulating the ethanol-scented toy when compared with the unscented toy. Moreover, differential exposure to the odors of ethanol and vanilla, as indicated by differential consumption of alcohol by a parent or use of vanilla-scented product by the mother, was related to differential responses to these odors. These findings suggest that human infants are able to detect and retain information about the chemical features of their environment.