Comparison of intake of nicotine from environmental tobacco smoke between nose and mouth breathers

Two experiments were carried out in order to investigate nicotine intake through passive smoking. In the first study, carboxyhemoglobin (COHb) and serum cotinine were found to increase to a similar extent in seven subjects breathing through the nose only and in another seven subjects breathing through the mouth only during exposure to environmental tobacco smoke. Similarly, no significant difference was found in urinary excretion of nicotine and cotinine over a period of 72 hours, although nicotine and cotinine excretion tended to be slightly higher after inhalation through the nose only. In the second study, nicotine was measured in four subjects who held mainstream or sidestream smoke in the mouth without inhaling. Cotinine levels in serum and amounts of nicotine and cotinine excreted in the urine were low compared with those measured in the breathing study. Nicotine from sidestream smoke, however, is more effectively absorbed by the oral mucosa than nicotine from mainstream smoke. The data suggest that nicotine intake from passive smoking largely takes place in the bronchial tree and that nicotine absorption via the nasal or the oral mucosa is only of minor significance.     

Changes in soil respiration across a chronosequence of tallgrass prairie reconstructions

Close relationships among climatic factors and soil respiration (R_s) are commonly reported. However, variation in R_s across the landscape is compounded by site-specific differences that impede the development of spatially explicit models. Among factors that influence R_s, the effect of ecosystem age is poorly documented. We hypothesized that R_s increases with grassland age and tested this hypothesis in a chronosequence of tallgrass prairie reconstructions in central Iowa, U.S.A. We also assessed changes in root biomass, root ingrowth, aboveground net primary productivity (ANPP), and the strength of soil temperature and moisture in predicting R_s. We found a significant increase in total growing season R_s with prairie age (R² = 0.79), ranging from 714 g C m^?2 in the youngest reconstruction (age 4) to 939 g C m^?2 in the oldest prairie (age 12). Soil temperature was a strong predictor of intra-seasonal R_s among prairies (R² = 0.78–0.87) but mean growing season soil temperature and moisture did not relate to total R_s. The increase in R_s with age was positively correlated with root biomass (r = 0.80) and ANPP (r = 0.87) but not with root ingrowth. Our findings suggest that growing season R_s increases with tallgrass prairie age, root biomass, and ANPP during young grassland development.     

Lipid (energy) reserves,utilisation and provisioning during oocyte maturation and early embryonic development of deepwater chondrichthyans

We studied the lipid dynamics (lipid contents, classes and fatty acids) during oogenesis and early embryogenesis of 7 viviparous and 3 oviparous deepwater chondrichthyans. Mature pre-ovulated ovarian follicles of all species were high in lipid content, indicative of large energetic expenditure and high maternal investment. Larger lipid reserves were found in viviparous dogshark (28–36% wet weight, ww) compared to oviparous chimaeras (19–24% ww) and catshark, F. boardmani (18% ww). Neutral lipids and monounsaturated fatty acids were the main source of lipidic energy during vitellogenesis and gestation. For most species, there was a peak in total lipid content, levels of storage lipids and essential fatty acids at time of ovulation. Interspecific variation of total lipid yolk reserves and lipid class profiles was largely explained by differences in parity mode, reproductive (continuous vs. non-continuous oocytes development) strategy and depth-related physiological adaptations. Fatty acid profiles were less variable among species with the most important fatty acids including: 16:0, 18:1ω9, 20:1ω9, 20:4ω6 and 22:6ω3. These findings provide a greater biochemical understanding of different maternal-embryonic relationships among chondrichthyans, which can be used as a baseline for subsequent comparative studies.     

Corrigendum to “Development and characterization of monoclonal antibodies against human aryl hydrocarbon receptor” [J. Environ. Sci. 39 (2016) 165–174]

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