The biogenic silica extracted from samples of 28 alpine plant species belonging to 23 genera and nine families collected in the Swiss Alps (Valais) accounted for between 0.01 and 5.9% of the dry ...biomass of leaves and wood. Silica content, and plant contribution to the soil biogenic silica pool, varied widely among taxa. Plant net productivity and biogenic silica production from this study and from the literature have been used to predict the input made by different subalpine and alpine plant communities to soil-borne phytolith assemblages, and their contribution to the silicon biocycle.
Objective: Histoplasmosis is a granulomatous fungal disease caused by Histoplasma capsulatum. The objective of the present paper was to describe the prevalence of oral histoplasmosis (OH) in two ...services from an endemic area in Argentina between 1991 and 2002 and to compare the clinicopathological profile of OH between HIV‐positive and HIV‐negative patients.
Methods: About 733 HIV+ (group A) and 14 260 patients (group B) were examined. Clinical diagnosis was confirmed by cytology, biopsy or culture.
Results: About 21 (3%) and 10 (0.07%) cases of OH were diagnosed in group A and B respectively. Most patients were male. A total of 90% of patients in group A were <45 years old whereas 70% of group B were more than 45 years old. Palate, gingiva and oropharynx were the most frequent locations. The importance of including histoplasmosis in the differential diagnosis of ulcerated oral lesions in immunocompromised patients was discussed.
This paper reports general patterns of relative growth rate and
related traits in response to elevated atmospheric
CO2 in eight woody species ranging widely in life form, leaf
habit, taxonomy and ...ecology. Young plants of these
species, all of comparable ontogenetic phases, were grown simultaneously
in large containers with favourable
nutrient and water availability in transparent outdoor chambers at 350
and 700 μl l−1 CO2 for one growing season.
We found the following consistent responses. (1) All species grew faster
at elevated CO2, whereas the following
leaf and allocation traits were consistently lower in CO2-enriched
environments: specific leaf area (quotient of leaf
area and leaf weight), leaf area ratio (quotient of total leaf area and
plant weight), weight-based foliar N
concentration and, to a smaller extent, leaf weight fraction (quotient
of leaf weight and plant weight). (2) There
was important interspecific variation in the magnitude of the response
of relative growth rate to CO2. Specific leaf
area at ambient CO2 explained 88% of the variation in relative
growth rate response to CO2 among the eight
species. At ambient CO2, relative growth rate itself, was significantly
correlated with the relative growth rate
response to CO2 only if the leafless species Ulex gallii
was excluded from analysis. (3) The four deciduous species
had a significantly stronger relative growth rate response to CO2
than the four evergreens. This corresponded with
their generally higher specific leaf area. (4) Specific leaf area and leaf
habit might be useful for scaling up exercises,
as easy-to-measure substitutes for growth responses of (woody) vegetation
to elevated CO2. However, the
usefulness of such traits in this context needs to be tested in realistic,
longer-term manipulative experiments in
real ecosystems.
1 Stands of the annual Brassica kaber were grown at a range of six densities in both ambient and elevated CO2environments, and measurements of shoot growth were made from seedling emergence through ...to reproduction. 2 Early in stand development (21 days following emergence), CO2enhancement (β) for above-ground biomass was highly density-dependent, ranging from 1.41 at the lowest density (20 plants m-2) to 0.59 at the highest density (652 plants m-2). 3 As stands matured and total biomass exceeded a relatively low threshold level (< 10.0 g m-2; c. 20% of final yield), the density-dependence of β disappeared. Above this shoot biomass threshold, β-values remained remarkably stable (β = 0.34) across a broad range of stand biomass, independent of a stand's initial density or age. 4 Average stand-level reproductive β-values at a final harvest were very similar to biomass values (β = 0.38) and, as with biomass values at later stages, showed no apparent density-dependence. 5 These results highlight the importance of considering density and the time-course of stand development simultaneously when assessing the potential for CO2-induced growth enhancements in plants.
The effect of controlled proteolysis on the plasma membrane (PM) Ca2+-ATPase was studied at the molecular level in PM purified from radish (Raphanus sativus L.) seedlings. Two new methods for ...labeling the PM Ca2+-ATPase are described. The PM Ca2+-ATPase can be selectively labeled by treatment with micromolar fluorescein isothiocyanate (FITC), a strong inhibitor of enzyme activity. Both inhibition of activity and FITC binding to the PM Ca2+-ATPase are suppressed by millimolar MgITP. The PM Ca2+-ATPase maintains the capability to bind calmodulin also after sodium dodecyl sulfate gel electrophoresis and blotting; therefore, it can be conveniently identified by 125I-calmodulin overlay in the presence of calcium. With both methods a molecular mass of 133 kD can be calculated for the PM Ca2+-ATPase. FITC-labeled PM Ca2+-ATPase comigrates with the phosphorylated intermediate of the enzyme-- labeled by incubation with gamma-32PGTP in the presence of calcium--on acidic sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Controlled trypsin treatment of purified PM determines a reduction of the molecular mass of the PM Ca2+-ATPase from 133 to 118 kD parallel to the increase of enzyme activity. Only the 133-kD but not the 118-kD PM Ca2+-ATPase binds calmodulin. These results indicate that trypsin removes from the PM Ca2+-ATPase an autoinhibitory domain that contains the calmodulin-binding domain of the enzyme
In this work, we exploited the capability of the plasma membrane Ca-ATPase to utilize ITP as a substrate to study its characteristics in plasma membrane vesicles purified from radish (Raphanus ...sativus L.) seedlings. The majority of the ITPase activity of plasma membrane was Ca2+-dependent. The Ca2+-dependent ITPase activity was Mg2+-dependent and was stimulated by the calcium ionophore A23187. It was inhibited by erythrosin B (concentration giving 50% inhibition, 50 nanomolar) and by vanadate (concentration giving 50% inhibition, 3 micromolar) and displayed a broad pH optimum around pH 7.2 to 7.5. Both the hydrolytic and the transport activity of the plasma membrane Ca-ATPase were half-saturated by Ca2+ in the micromolar concentration range. No major effect of EGTA on the saturation kinetics of the enzyme was observed. The affinity of the plasma membrane Ca-ATPase for Ca2+ was about fourfold higher at pH 7.5 than at pH 6.9. The Ca2+-dependent ITPase activity was stimulated about twofold by polyoxyethylene 20 cetyl ether, although it was inhibited by Triton X-100 and by lysolecithin.
Biogenic silica extracted from 21 species commonly occurring in subalpine and alpine plant communities in the central Swiss Alps were examined using light and SEM microscopes; 19 species being ...screened here for the first time. An inventory of phytolith types is provided and type-frequencies are assessed. Light microscope photographs and SEM micrographs provided illustrations of the types described. The monocotyledons analysed belonged to the genera
Calamagrostis,
Festuca,
Nardus,
Poa and
Carex. Monocotyledons yielded mainly types of epidermal origin (short cells, rods, cork cells, silicified stomata and trichomes).
Dicotyledons analysed were from five genera of the Ericaceae family (
Arctostaphylos,
Calluna,
Loiseleuria,
Rhododendron,
Vaccinium) and from one genus of the Betulaceae (
Alnus). In dicotyledons, silicified epidermal jigsaw cells, stomata complexes and vessels were recovered.
Conifer species of the genera
Abies,
Juniperus,
Picea,
Pinus and
Larix were studied. Distinctive conifer cells were mainly silicified endodermids and transfusion tissues. Phytolith taxonomic diagnostic potential was tested by cluster analysis and principal component analysis (PCA). It was shown that grass and sedge species could be easily differentiated on the basis of phytolith types. In general, Ericaceae and conifers could also be distinguished on the basis of phytoliths; however, some species yielding mainly redundant types were not unequivocally identifiable.
The aim of the present work is to provide a framework for phytolith-based plaeoecological studies at the treeline in the European Alps.
The effects of calmodulin and of controlled trypsin treatments on the activity of the Ca2+ pump were investigated in plasma membrane purified from radish (Raphanus sativus L.) seedlings. Treatment of ...the plasma membrane with ethylenediaminetetra-acetate (EDTA), which removed about two-thirds of the plasma membrane-associated calmodulin, markedly increased the stimulation of the Ca2+ pump by calmodulin. In EDTA-treated plasma membrane, stimulation by calmodulin of the Ca2+ pump activity was maximal at low free Ca2+ (2-5 muM) and decreased with the increase of free Ca2+ concentration. The Ca2+ pump activity was stimulated also by a controlled treatment of the plasma membrane with trypsin: the effect of trypsin treatment depended on the concentration of both trypsin and plasma membrane proteins and on the duration of incubation. Stimulation of the Ca2+ pump activity by trypsin treatment of the plasma membrane was similar to that induced by calmodulin both in extent and in dependence on the free Ca2+ concentration in the assay medium. Moreover, the Ca2+ pump of trypsin-treated plasma membrane was insensitive to further stimulation by calmodulin, suggesting that limited proteolysis preferentially cleaves a regulatory domain of the enzyme that is involved in its activation by calmodulin.
The uppermost limits of past treelines in the Alps are established using soil type and soil charcoal mass. In all the studied sites, a sharp decrease of soil charcoal mass is correlated with the ...upper altitudinal limit of podzols. On the basis of this evidence, the uppermost tree limit reached 2500±100m a.s.l. in the Valaisan Alps during the Holocene, i.e., it was 250±100 m higher than today's potential treeline. Consequently, the timberline would have reached 2400±100m a.s.l.. From the strong decline of charcoals concentration in soils above 2500m a.s.l., we infer that conifer species were rare or very rare above this altitude during the Holocene. Joint interpretation of charcoal, pollen, soil and macrofossil data suggest that alpine meadows with at most scattered conifers were present throughout the Holocene in the today's middle and upper alpine belt.
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