Development of ground vegetation biomass and nutrient pools in a clear-cut disc-plowed boreal forest

Nutrient leaching from forest substrate after clear-cutting and subsequent soil preparation is strongly influenced by the capacity of ground vegetation to sequester the released nutrients. We studied the rates and patterns of biomass and nutrient accumulation in ground vegetation growing on ridges, in furrows and on undisturbed surfaces for 2–5 years after disc-plowing in eastern Finland. The biomass of mosses on ridges remained significantly lower than that in furrows and on undisturbed surfaces. Field layer biomass on ridges and in furrows was significantly lower than on undisturbed surfaces throughout the study period. Field layer biomass increased more on ridges than in furrows. Root biomass on ridges and undisturbed surfaces was considerably higher than in furrows. Five years after disc-plowing, total biomass and nutrient pools for ridges (biomass 4,975 kg ha⁻¹, N 40 kg ha⁻¹, P 5 kg ha⁻¹, K 20 kg ha⁻¹ and Ca 18 kg ha⁻¹) and undisturbed surfaces (biomass 5,613 kg ha⁻¹, N 43 kg ha⁻¹, P 5 kg ha⁻¹, K 22 kg ha⁻¹ and Ca 18 kg ha⁻¹) were similar, but considerably lower for furrows (biomass 1,807 kg ha⁻¹, N 16 kg ha⁻¹, P 2 kg ha⁻¹, K 10 kg ha⁻¹ and Ca 6 kg ha⁻¹). Ridges covered 25% of the area, furrows 30 and 45% was undisturbed surfaces. Taking into account the proportion of each type of surface, values for the whole prepared clear-cut area were 4,312, 34, 4, 18 and 14 kg ha⁻¹ for biomass, N, P, K and Ca, respectively. Biomass and nutrient pools had not returned to uncut forest levels at the end of the 5-year study period. The results indicate that mosses and field layer vegetation respond differently to soil preparation, that the development of biomass on ridges, in furrows and on undisturbed surfaces proceeds at different rates, and that the biomass and nutrient uptake of ground vegetation remains below pre-site preparation levels for several years. However, ridges, which are known to be the most susceptible to leaching, revegetate rapidly. Responsible Editor: Tibor Kalapos.     

Eudismic analysis of tricyclic sesquiterpenoid alcohols: lead structures for the design of potent inhibitors of the human UDP-glucuronosyltransferase 2B7

The epimeric tricyclic sesquiterpenoid alcohols globulol, epiglobulol, cedrol, epicedrol, longifolol, and isolongifolol were investigated in their ability to inhibit the recombinant human UDP-glucuronosyltransferase (UGT) 2B7. The stereoisomers displayed rapidly reversible competitive inhibition, which was substrate-independent. Longifolol and its stereoisomer isolongifolol displayed the lowest competitive inhibition constants (K(ic)) of 23 and 26 nM, respectively. The K(ic) values of cedrol and its epimer epicedrol were 0.15 and 0.21 microM, those of globulol and epiglobulol were 5.4 and 4.0 microM, respectively. The diastereomeric alcohols exhibited nearly identical affinities toward UGT2B7 indicating that the spatial arrangement of the hydroxy group had no influence on the dissociation of the enzyme-terpenoid complex. The high affinities stemmed presumably from mere hydrophobic interactions between the hydrocarbon scaffold of the terpenoid alcohol and the binding site of the enzyme. Glucuronidation assays revealed that there were large differences in the rates at which the epimeric alcohols were conjugated. Therefore, the spatial arrangement of the hydroxy group controlled the rate of the UGT2B7-catalyzed reaction. The introduction of a methyl group into the side chain of isolongifolol and longifolol increased the steric hindrance. As a result, the rate of the UGT2B7-catalyzed reaction was decreased by more than 88%. The findings indicated that the rate of the UGT2B7-catalyzed glucuronidation is significantly controlled by stereochemical and steric factors. Considering the high inhibition levels exerted by the tricyclic sesquiterpenoid alcohols, these compounds might serve as valuable lead structures for the design of potent inhibitors for UGT2B7.     

Forest floor vegetation response to nitrogen deposition in Europe

Chronic nitrogen (N) deposition is a threat to biodiversity that results from the eutrophication of ecosystems. We studied long‐term monitoring data from 28 forest sites with a total of 1,335 permanent forest floor vegetation plots from northern Fennoscandia to southern Italy to analyse temporal trends in vascular plant species cover and diversity. We found that the cover of plant species which prefer nutrient‐poor soils (oligotrophic species) decreased the more the measured N deposition exceeded the empirical critical load (CL) for eutrophication effects (P = 0.002). Although species preferring nutrient‐rich sites (eutrophic species) did not experience a significantly increase in cover (P = 0.440), in comparison to oligotrophic species they had a marginally higher proportion among new occurring species (P = 0.091). The observed gradual replacement of oligotrophic species by eutrophic species as a response to N deposition seems to be a general pattern, as it was consistent on the European scale. Contrary to species cover changes, neither the decrease in species richness nor of homogeneity correlated with nitrogen CL exceedance (ExCL_empN). We assume that the lack of diversity changes resulted from the restricted time period of our observations. Although existing habitat‐specific empirical CL still hold some uncertainty, we exemplify that they are useful indicators for the sensitivity of forest floor vegetation to N deposition.     

Multiple Dimensions of Socioeconomic Position and Obesity among Employees: The Helsinki Health Study

Objective: To examine socioeconomic differences in obesity using several different socioeconomic indicators, ranging from childhood socioeconomic environment and adult socioeconomic status to material resources and economic satisfaction. Research Methods and Procedures: The data derived from the Helsinki Health Study baseline surveys in 2000 and 2001. Respondents to postal surveys were middle‐aged employees of the City of Helsinki (4, 975 women and 1, 252 men, response rate 68%). Associations between eight socioeconomic indicators and obesity (BMI ≥ 30 kg/m²), calculated from self‐reported data, were examined by fitting a series of logistic regression models. Results: In women, all socioeconomic indicators except household income and economic satisfaction were associated with obesity. Parental education and childhood economic difficulties, i.e., socioeconomic conditions in childhood, remained associated with obesity after adjusting for all indicators of current socioeconomic position. Indicators of adult socioeconomic status, own education and occupational class, were no longer associated with obesity when childhood socioeconomic conditions were adjusted for. Home ownership and economic difficulties were associated with obesity after full adjustments. In men, the findings paralleled those among women, but few associations reached statistical significance. Discussion: Obesity was associated with several dimensions of socioeconomic position. Childhood socioeconomic disadvantage was associated with obesity independently of the various indicators of current socioeconomic position. Associations between obesity and both educational level and occupational class disappeared after adjustment for other indicators of socioeconomic position. This suggests that the variation observed in the prevalence of obesity by these key socioeconomic indicators may reflect differences in the related material resources.     

Gene defect in hypodontia: exclusion of MSX1 and MSX2 as candidate genes

Hypodontia, congenital lack of one or a few teeth, is an autosomally inherited dominant trait. Homeobox genes MSX1 and MSX2 are expressed in presumptive dental tissues at the stage of initiation of tooth development. Recently, tooth development was shown to be inhibited in transgenic mice lacking a functional Msx1 gene. Here, we studied the relationship of the MSX1 and MSX2 genes to familial hypodontia in five Finnish families with a total of 20 affected individuals, by linkage analysis. The pairwise lod-scores regarding the intragenic microsatellites in the MSX1 and MSX2 genes at a recombination fraction of 0.0 were -3.1 and -3.0, respectively, thus excluding these genes as causative loci for hypodontia in these families.     

LATERAL MANDIBULAR WALL THICKNESS IN TURSIOPS TRUNCATUS: VARIATION DUE TO SEX AND AGE

In odontocetes the mandibular bone serves two functions: to capture prey, and as a means of the reception and transmission of sound waves through a fat body in the mandibular canal, which opens posteriorly as the mandibular foramen. The posterior part of the lateral wall of the odontocete mandible is thin, and appears to represent a compromise between a strong mandible for prey capture and a thin vibrating plate for hearing. We studied the intraspecific variation of minimum thickness of the lateral mandibular wall along four transects (T1-T4) at the area of the mandibular foramen, in relation to the skull size and the mandibular size in different-aged bottlenose dolphins, Tursiops truncatus (18 females between 1 and 42 yr, 17 males between 1 and 32 yr). The minimum thickness was absolutely at its lowest at the most posterior transect T1, but did not vary significantly between the sexes or between the ages. The minimum thickness varied significantly at the two most anterior transects, T3 and T4, both between the sexes and among the ages. The thickness increased throughout life among males, whereas in females it first increased and then starts to decrease around the age of 20.     

Cell surface proteins of encapsulated Streptococcus cremoris: identification and immunochemical characterization

Cell surface proteins of two slime-forming, encapsulated Streptococcus cremoris strains, MLS96 and T₅ from the fermented milk product viili, were extracted with the non-ionic detergent Triton X-100. The isolated protein antigens were characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immuno-blotting with antisera produced against whole Strep. cremoris cells. When protein profiles of these strains were compared, seven prominent polypeptides were found common to both and were recognized by both antisera. Five of these polypeptides with molecular weights of 70000, 54000, 50000, 47000 and 40000 were identified as cell wall components. The remaining two polypeptides with molecular weights of 42000 and 26000 are being studied further in connection with slime formation for which modified Triton X-100 extraction provides a suitable method for isolation of the surface-associated antigens of lactic streptococci.