Metabolism of stevioside by chickens

In intubation experiments (643-1168 mg per animal), most of the stevioside administered to chickens was recovered unchanged in the excreta, and only about 2% was converted into steviol. Neither stevioside nor steviol could be found in the blood. In chronic studies (667 mg of stevioside/kg of feed) with laying hens and meat-type chickens, no significant differences were found in feed uptake, weight gain, and feed conversion as the result of stevioside administration. The egg production and egg composition of laying hens were not influenced. Most of the stevioside taken up was found untransformed in the excreta, and about 21.5% or 7.3% was converted to steviol by meat-type chickens or laying hens, respectively. No stevioside or steviol could be detected in the blood or in the eggs of the different groups of animals. In anaerobic incubation experiments with chicken excreta, only a 20% conversion of stevioside into steviol was found. No harmful effects were observed in the chronic stevioside supplementation experiments nor in the intubation experiments in which very high stevioside doses were given.     

Effect of soil compaction on hydraulic properties of two loess soils in China

Soil compaction affects hydraulic properties, and thus can lead to soil degradation and other adverse effects on environmental quality. This study evaluates the effects of three levels of compaction on the hydraulic properties of two silty loam soils from the Loess Plateau, China. Undisturbed soil cores were collected from the surface (0–5 cm) and subsurface (10–15 cm) layers at sites in Mizhi and Heyang in Shaanxi Province. The three levels of soil compaction were set by increasing soil bulk density by 0% (C0), 10% (C1) and 20% (C2) through compression and hammering in the laboratory. Soil water retention curves were then determined, and both saturated hydraulic conductivity (K_s) and unsaturated hydraulic conductivity were estimated for all of the samples using standard suction apparatus, a constant head method and the hot-air method, respectively. The high level of compaction (C2) significantly changed the water retention curves of both the surface and subsurface layers of the Heyang soil, and both levels of compaction (C1 and C2) changed the curves of the two layers from the Mizhi site. However, the effects of compaction on the two soils were only pronounced below water tensions of 100 kPa. Saturated hydraulic conductivities (K_s) were significantly reduced by the highest compaction level for both sampled layers of the Heyang soil, but no difference was observed in this respect between the C0 and C1 treatments. K_s values decreased with increasing soil compaction for both layers of the Mizhi soil. Unsaturated hydraulic conductivities were not affected by soil compaction levels in the measured water volume ratio range, and the values obtained were two to five orders of magnitude higher for the Mizhi soil than for the Heyang soil. The results indicate that soil compaction could strongly influence, in different ways, the hydraulic properties of the two soils.     

Prolonged elevated atmospheric CO2 does not affect decomposition of plant material

Prolonged elevated atmospheric CO₂ might alter decomposition. In a 90-day incubation study, we determined the long-term (9 years) impact of elevated CO₂ on N mineralization of Lolium perenne and Trifolium repens plant material grown at ambient and elevated CO₂ and low- and high-¹⁵N fertilizer additions. No significant differences were observed in recovery rates between any of the treatments, except an N addition effect was observed for L. perenne (0.4 versus 0.5% day⁻¹ in high versus low N). The results suggest that elevated CO₂ did not change plant N mineralization in any of the soils, because of a surplus of available N in the fertilized and leguminous systems, and because of insignificant plant responses to elevated CO₂ in the low soil N availability systems.     

Is breakfast consumption related to mental distress and academic performance in adolescents?

OBJECTIVE: To examine the relationship between mental distress, academic performance and regular breakfast consumption across gender and immigration status. DESIGN: Cross-sectional population-based study. Two four-page questionnaires were filled in during two school sessions. SETTING: All junior high schools in Oslo, Norway using the classroom as the setting for the study. SUBJECTS: All 10th grade students 15-16 years olds in 2000 and 2001. Of 8316 eligible students, 7343 (88.3%) participated in the study. RESULTS: All immigrant groups, except the Western countries group, are skipping breakfast more often than Norwegian students, and girls more often than boys (27 versus 19%). After adjustment for possible confounding factors, the odds ratio (OR) for being mentally distressed when eating breakfast seldom/never compared with every day was 3.0 (2.0-4.5) for boys, 1.6 (1.2-2.1) for girls and 1.6 (1.5-2.6) for the immigrant group. The comparable OR for having low school grades was similar for boys and girls, 2.0 (1.3-3.0), and 1.6 (1.5-2.6) for the immigrant groups. CONCLUSIONS: Skipping breakfast is a common feature among 10th grade students. The implications of skipping breakfast on mental distress and academic performance are stronger for boys than girls and stronger for Norwegians compared with immigrants.     

Biphasic effect of falcarinol on caco-2 cell proliferation, DNA damage, and apoptosis

The polyacetylene falcarinol, isolated from carrots, has been shown to be protective against chemically induced colon cancer development in rats, but the mechanisms are not fully understood. In this study CaCo-2 cells were exposed to falcarinol (0.5-100 microM) and the effects on proliferation, DNA damage, and apoptosis investigated. Low-dose falcarinol exposure (0.5-10 microM) decreased expression of the apoptosis indicator caspase-3 concomitantly with decreased basal DNA strand breakage. Cell proliferation was increased (1-10 microM), whereas cellular attachment was unaffected by <10 microM falcarinol. At concentrations above 20 microM falcarinol, proliferation of CaCo-2 cells decreased and the number of cells expressing active caspase-3 increased simultaneously with increased cell detachment. Furthermore, DNA single-strand breakage was significantly increased at concentrations above 10 microM falcarinol. Thus, the effects of falcarinol on CaCo-2 cells appear to be biphasic, inducing pro-proliferative and apoptotic characteristics at low and high concentrations of falcarinol, respectively.     

Significance of old aspen (Populus tremula) trees for the occurrence of lichen photobionts

In the boreal forest landscape, aspen has been effectively selected against in favour of conifers. The decrease in aspen is of particular concern, since it has more host-specific species associated with it than any other boreal tree species. Recently, forest management systems have begun to include green-tree retention in order to maintain structural diversity. Earlier studies have focused on the importance of remnant aspen trees for lichen species prevalence. We have focused on the occurrence of free-living photobionts, i.e. cyanobacteria and green-algae, since a successful establishment of sexually dispersed lichens will depend upon the presence of the photobiont. Our study shows that the abundances of Gloeocystis, Nostoc, Scytonema and Trentepohlia increased with stand age, while the abundance of Trebouxia decreased. The response to clear-felling differed between genera. The two cyanobacterial genera were able to persist in clear-cuts, although they were more abundant on the northern side of the remnant trees. The green-algae showed no consistent pattern, Trentepohlia was affected while Trebouxia was unaffected. Our study indicates that the prerequisites for new-establishment for spore dispersed lichen species, on remnant aspen, may be fulfilled in terms of availability of free-living photobionts on the northern side of the trunks. In support of this interpretation we found that the occurrence of cyanolichens was positively correlated with the occurrence of free-living cyanobacteria in the clear-cuts. We conclude that tree retention is likely to provide a useful tool for increasing biodiversity in managed forest landscapes provided that source populations still exist in the surrounding landscape.     

Can artificial introductions of diaspore fragments work as a conservation tool for maintaining populations of the rare peatmoss Sphagnum angermanicum?

Species can become regionally rare when limited by the availability of suitable habitats or by limited dispersal ability. We tested if the presence of a rare bryophyte species (Sphagnum angermanicum) was dispersal or habitat limited and at the same time investigated the possibility of establishing new populations of this rare species. Further, we tested how propagule (fragment) size and small scale disturbances affected establishment success. All field experiments were performed by artificially transporting propagules (of various sizes) to new and old sites for the species in Sweden.We show that S. angermanicum is dispersal limited on a regional scale, as no significant differences in establishment success were found between new suitable sites and old occupied sites. The larger the propagule the better was the establishment success; the best establishment success was found when transplanting whole shoots. Disturbances did not increase establishment success, in contrary, when compared to controls success was reduced by the more intensive disturbance treatments. We suggest that disturbance maybe more important for increasing direct dispersal than for making the microhabitat more advantageous for establishment. However, an intermediate disturbance, which slightly reduces the Sphagnum-community length increment, might also be beneficial for the establishment success of S. angermanicum propagules.The reasonably high establishment success of S. angermanicum propagules in new suitable sites suggests that artificial introductions of fragments could be considered as an active management regime for the species if the number of localities continues to decrease.     

History and forest biodiversity of woodland key habitats in south boreal Sweden

Forest exploitation has destructed forest habitats in Fennoscandia during last centuries. Vital components of existing forest biodiversity have been identified as small (a few ha) woodland key habitats (WKHs). Many WKHs in boreal forest landscapes are assumed to represent remnant near-natural forests from before the phase of industrial forest exploitation. Thus, WKHs are supposed to (i) exhibit a low degree of exploitation, (ii) have old-growth characteristics and (iii) host Red-list species. Yet, WKHs’ history and biodiversity have not been systematically investigated. Thus, their conservation values remain unclear. This study investigates history and biodiversity of 15 WKHs in central Sweden with retrospective methods and field studies. We analyze (1) forest structure before, during and after the forest exploitation period, (2) existing biodiversity, i.e. species and structural elements, and (3) to what extent human activities (forestry) have influenced current biodiversity. Our results indicate that forest structure within the areas that currently are classified as WKHs has changed dramatically since the mid-19th century, when forests were unaffected by logging. The results suggest that fire-suppression during last century, gradually increased logging until mid-20th century and abandonment by modern forestry during the late 20th century, are main causes behind this transformation. Less than 10% of studied WKHs had biological features that resembled those of pristine boreal forests. Thus, most studied WKHs cannot be classified as near-natural or remnants of pristine forest. We suggest that the program for WKHs give more focus to pre-industrial forest structure, local historical aspects being seriously regarded and ecological restoration efforts being introduced.     

Efficiency of Bark, Activated Charcoal, Foam and Sand Filters in Reducing Pollutants from Greywater

Greywater is a potential resource of water that can be improved to meet the quality needed for irrigation. This study evaluated the performance of bark, activated charcoal, polyurethane foam and sand filters in removing biochemical oxygen demand (BOD₅), surfactants, phosphorus, nitrogen and microbial indicators from greywater during start-up and steady state. In column experiments, 0.6?m high filters (diameter 20?cm) were fed for 113?days with artificial greywater at a hydraulic loading rate of 0.032?m³?m^?2?day^?1 and an organic loading rate of 0.014?kg BOD₅ m^?2?day^?1. Bark and activated charcoal efficiently reduced the concentrations of organics (BOD₅), surfactants (methylene blue active substances??MBAS), total phosphorus (Tot-P) and total thermotolerant coliform numbers, while sand and foam were less efficient. Bark, activated charcoal, foam and sand reduced influent BOD₅ by 98, 97, 37 and 75?%; MBAS by >99, >99, 73 and 96?%; Tot-P by 97, 91, 36 and 78?%; and total nitrogen by 19, 98, 13 and 5?%, respectively. BOD₅ and MBAS were efficiently reduced directly from start-up by bark and activated charcoal, while foam needed 30?days to achieve about 50?% reduction in BOD₅. Bark was the most efficient filter in reducing thermotolerant faecal coliforms (2.4 log₁₀), while foam achieved the lowest reduction (0.5 log₁₀). Overall, bark and activated charcoal filters appeared to be the most suitable filters for improving greywater quality to reach irrigation quality in terms of organic matter reduction. Performance of these filters under higher and fluctuating loadings and the long-term sustainability of the filter materials need further investigation.