Effect of experimental nitrogen load on methane and nitrous oxide fluxes on ombrotrophic boreal peatland

Methane (CH₄) and nitrous oxide (N₂O) dynamics were studied in a boreal Sphagnum fuscum pine bog receiving annually (from 1991 to 1996) 30 or 100 kg NH₄NO₃-N ha^–1. The gas emissions were measured during the last three growing seasons of the experiment. Nitrogen treatment did not affect the CH₄ fluxes in the microsites where S. fuscum and S. angustifolium dominated. However, addition of 100 kg NH₄NO₃-N ha^–1 yr^–1 increased the CH₄ emission from those microsites dominated by S. fuscum. This increase was associated with the increase in coverage of cotton grass (Eriophorum vaginatum) induced by the nitrogen treatment. The differences in the CH₄ emissions were not related to the CH₄ oxidation and production potentials in the peat profiles. The N₂O fluxes were negligible from all microsites. Only minor short-term increases occurred after the nitrogen addition.     

Evaluation of Bioremediation Treatments in a Shoreline-Simulating Microcosm

A microcosm test was designed to study the efficiency of bioremediation treatments at oil contaminated shorelines. The biodegradation in the hermetically closed microcosm was monitored by measuring the total cumulative inorganic carbon evolved during the bioremediation process. The effects of three different additives, medium-release methylene urea (MU) + apatite, fast-release MU + superphosphate, and a biosorbent, on the biodegradation of weathered crude oil (North Sea Brent) were evaluated at +10°C. All the additives significantly increased mineralization. The total amount of inorganic carbon evolved during the 10-week study was measured in the microcosm treated with oil, and with oil and medium-release MU + apatite, fast-release MU + superphosphate, and biosorbent. The amounts were 40,670,490, and 580 mg, respectively. The respirometric measurements were supported by microbiological determinations, ATP content in the sand, number of heterotrophic bacteria, and amount of biomass-C determined by the substrate-induced respiration method. Nutrient analysis indicated that biodegradation was nitrogen limited. The microcosm test proved to be suitable for comparing the effectiveness of different treatments in enhancing the biodegradation of crude oil-contaminated shores.     

Combined UV and Liquid Scintillation Detection in HPLC. Formation and Depurination of Substitution Inert Pt(II) Complexes of Purine Nucleosides

Abstract

Combined UV- and liquid scintillation-HPLC has been applied to study the complexing of purine nucleosides with Pt(II)-diamine ions, and the effect of the complex formation on the acidic depurination.     

The effect of progesterone on the localization of progesterone receptors in the nuclei of chick oviduct cells

Summary The location of occupied and unoccupied progesterone receptors (PR) in chick oviduct cells was studied by immuno-electron microscopy with the use of a highly specific polyclonal anti-PR antibody and pre-embedding modifications of the peroxidase-anti-peroxidase-(PAP-) or immunogold-silver methods. Both methods revealed a nuclear localization of the PRs. The location of the PR in the nucleus was studied in detail by means of the immunogold-silver method. The most intense labelling for unoccupied PRs was in the condensed chromatin. After occupation of PRs with progesterone (P), decondensation or dispersion of chromatin was observed. At the same time, the labelling in the border area of condensed and dispersed chromatin, and in the dispersed chromatin, increased. The changes were statistically significant. The results can be explained by conformational changes of the PR-containing chromatin rather than by translocation of PRs from one site to another.     

Intermediate filament proteins and epithelial differentiation in the embryonic ovary of the rat

Abstract. The development and sexual differentiation of gonads in female rat embryos and fetuses between the ages of 11 and 17 days was studied by immunocytochemical analysis of intermediate filament proteins and laminin by light and electron microscopy. In the 11-day-old pregonadal embryo, the surface epithelial cells in the ventral cortex of the mesonephros contained desmin but not cytokeratin or vimentin. The development of the gonad began on the following day by proliferative growth of the mesonephric surface cells, which like the subepithelial cells soon expressed vimentin in addition to desmin. The differentiation continued by formation of separate epithelial cell clusters, which joined into cords, irregular in shape and size. Desmin disappeared from the cord cells and cytokeratins appeared while vimentin remained in all somatic cell types. Desmin was especially abundant in some stromal cells adjacent to the epithelial tissues. After the segration of the basic ovarian tissues, vimentin and desmin decreased and cytokeratins appeared in the surface epithelial cells. New changes in cytokeratin expression appeared with the differentiation of the embryonic cords in a sex-specific manner with gradual decrease of reactivity for cytokeratin 18. No immunoreaction to the neurofilament proteins was found at the present ages, and the germ cells were negative for intermediate filaments. The results show that desmin is expressed in several primitive ovarian and mesonephric cells even though they are not myogenic. The sexual differences emerge after the incipient formation of the genetically female gonad, as different organization of the internal epithelial tissue with different timing of changes in intermediate filament proteins when compared with the male gonad.     

Community structure of insect herbivores is driven by conservatism,escalation and divergence of defensive traits in Ficus

Escalation (macroevolutionary increase) or divergence (disparity between relatives) in trait values are two frequent outcomes of the plant‐herbivore arms race. We studied the defences and caterpillars associated with 21 sympatric New Guinean figs. Herbivore generalists were concentrated on hosts with low protease and oxidative activity. The distribution of specialists correlated with phylogeny, protease and trichomes. Additionally, highly specialised Asota moths used alkaloid rich plants. The evolution of proteases was conserved, alkaloid diversity has escalated across the studied species, oxidative activity has escalated within one clade, and trichomes have diverged across the phylogeny. Herbivore specificity correlated with their response to host defences: escalating traits largely affected generalists and divergent traits specialists; but the effect of escalating traits on extreme specialists was positive. In turn, the evolution of defences in Ficus can be driven towards both escalation and divergence in individual traits, in combination providing protection against a broad spectrum of herbivores.     

Shading enhances the quality of willow leaves to leaf beetles – but does it matter?

Plant shading is commonly recognised as a factor, which increases susceptibility of plants to attack by herbivorous insects. In this study we experimentally investigated the effect of host plant shading on two willow-feeding leaf beetles, Galerucella lineola feeding upon Salix phylicifolia and Phratora vitellinae feeding upon Salix myrsinifolia . Both beetle species were more abundant on potted willows growing in open habitats than on the same clones placed under the shade of trees. However, in the laboratory the food preference by adults and larval performance showed that the shaded willows are actually better food for both beetle species. On the contrary, when larvae were reared in the field under natural abiotic conditions, we found no difference in larval performance, or if any, even better performance in open habitats. Apparently, higher and more variable daily temperatures in open habitats accelerated the growth of the larvae. When adults were let to emigrate from or immigrate to potted willows, which had been grown in the same conditions but placed either in the open or shady habitats, adults preferred exposed willows. Invertebrate predators were more abundant in open habitats, but we found no differences in leaf beetle mortality by natural enemies between the habitats. Although the larval performance appeared to be approximately equal in the two habitats during the unusually warm study period, we suggest that under suboptimal temperatures the better abiotic conditions of open sites can easily override the better food provided by shaded habitats. The selection of abiotic habitat thus plays a significant role in the adaptive habitat and host plant selection of these beetles within the gradient of shadiness.     

Body Weight and Health Status: Importance of Socioeconomic Position and Working Conditions

Objective: To examine the association between relative body weight and health status and the potential modifying effects of socioeconomic position and working conditions on this association. Research Methods and Procedures: The data were derived from three identical cross‐sectional surveys conducted in 2000, 2001, and 2002. Respondents to postal surveys were middle‐aged employees of the City of Helsinki (7148 women and 1799 men, response rate 67%). BMI was based on self‐reported weight and height. Health status was measured by the Short‐Form 36 subscales and component summaries. Results: Body weight was inversely associated with physical health, but in mental health, differences between BMI categories were small and inconsistent. In women, physical health deteriorated monotonically with increasing BMI, whereas in men, poor physical health was found among the obese only. Socioeconomic position did not modify the association between BMI and health. In women, the association between body weight and physical health became stronger with decreasing job control and increasing physical work load, whereas in men, a similar modifying effect was found for high job demands. Discussion: Body weight was associated with physical health only. Lower levels of relative weight in women than in men may be associated with poor physical health. High body weight combined with adverse working conditions may impose a double burden on physical health.