Localization of callose in microspores and pollen grains in <Emphasis Type="Italic">Sium latifolium</Emphasis> L. plants in different water regimes

Results of studies of the topography and content of callose in the process of microsporogenesis as well as the formation of pollen grain in dry-valley and air-aquatic Sium latifolium L. plants grown under the conditions of different water regimes are presented. An increase in the content of callose in the microspore walls at the tetrad stage and in the pollen grains of dry-valley S. latifolium plants is discovered based on the intensity of fluorescence of the callose and a quantitative luminescence analysis. This result is obviously associated chiefly with the function of callose in maintaining moisture under conditions of water deficit.     

Study of P-glycoprotein effect on the lipid monolayer properties by the Langmuir-Blodgett technique

Expression of the P-glycoprotein (Pgp) is proved to be one of the main reasons for the development of the multidrug resistance (MDR) phenotype by cancer cells. The effect of Pgp on the properties of lipid monolayers was studied using membrane fractions of sensitive and Pgp over-expressing multidrug resistance cancer cells containing 11, 24 or 32% of Pgp relative to the total content of membrane proteins. The effect of the Pgp membrane concentration on the properties of monolayers prepared from the membrane fractions was analyzed by the Langmuir-Blodgett method. The subphase composition was found to play a critical role in the stability of monolayers at any Pgp concentration. The optimal subphase comprised 10 mM tris-HCl buffer, pH 6.5, which made it possible to create very stable monolayer films with the pressure of collapse of about 30-40 mN/m. Monolayers prepared from membrane fractions of sensitive cells and cells containing the maximum (32%) amount of Pgp were found to be much more stable compared with fractions comprising 11 or 24% of Pgp. The analysis of monolayer compression dynamics revealed three distinct stages: (1) the self-organization of lipid molecules, which is characterized by an abrupt change of surface potential; (2) the compression of Pgp molecules at the constant potential of monolayers; and (3) the compression of lipid molecules, which is characterized by a quasilinear increase of both pressure and surface potential. It was shown that the specific surface areas of monolayers formed from sensitive and Pgp-enriched membranes containing 11 or 24% of Pgp are very similar, whereas the surface area of the monolayer formed from membranes containing 32% of Pgp is nearly 1.5-fold greater. This fact may reflect the effect of the threshold rearrangement of the structure of lipid molecules or cooperative modifications of lipid-Pgp interactions induced by the increase in the Pgp content from 24 to 32%. The effect of verapamil, a well-known Pgp modulator, on the properties of monolayers was studied. It was show that verapamil is able to induce changes of the surface of Pgp-containing monolayers, and these modifications are maximal at the Pgp:verapamil 1:1 molar ratio. The data present the first experimental evidence for the possible intervention of Pgp modulator into the processes of lipid-lipid or lipid-Pgp cooperative interactions within Pgp-enriched membranes.     

Effects of forest management on the carbon dioxide emissions of wood energy in integrated production of timber and energy biomass

The aim of this work was to study the sensitivity of carbon dioxide (CO₂) emissions from wood energy to different forest management regimes when aiming at an integrated production of timber and energy biomass. For this purpose, the production of timber and energy biomass in Norway spruce [Picea abies (L.) Karst] and Scots pine (Pinus sylvestris L.) stands was simulated using an ecosystem model (SIMA) on sites of varying fertility under different management regimes, including various thinning and fertilization treatments over a fixed simulation period of 80 years. The simulations included timber (sawlogs, pulp), energy biomass (small‐sized stem wood) and/or logging residues (top part of stem, branches and needles) from first thinning, and logging residues and stumps from final felling for energy production. In this context, a life cycle analysis/emission calculation tool was used to assess the CO₂ emissions per unit of energy (kg CO₂ MWh^?1) which was produced based on the use of wood energy. The energy balance (GJ ha^?1) of the supply chain was also calculated. The evaluation of CO₂ emissions and energy balance of the supply chain considered the whole forest bioenergy production chain, representing all operations needed to grow and harvest biomass and transport it to a power plant for energy production. Fertilization and high precommercial stand density clearly increased stem wood production (i.e. sawlogs, pulp and small‐sized stem wood), but also the amount of logging residues, stump wood and roots for energy use. Similarly, the lowest CO₂ emissions per unit of energy were obtained, regardless of tree species and site fertility, when applying extremely or very dense precommercial stand density, as well as fertilization three times during the rotation. For Norway spruce such management also provided a high energy balance (GJ ha^?1). On the other hand, the highest energy balance for Scots pine was obtained concurrently with extremely dense precommercial stands without fertilization on the medium‐fertility site, while on the low‐fertility site fertilization three times during the rotation was needed to attain this balance. Thus, clear differences existed between species and sites. In general, the forest bioenergy supply chain seemed to be effective; i.e. the fossil fuel energy consumption varied between 2.2% and 2.8% of the energy produced based on the forest biomass. To conclude, the primary energy use and CO₂ emissions related to the forest operations, including the production and application of fertilizer, were small in relation to the increased potential of energy biomass.     

Effects of adaptation to periodic and continuous hypoxia in disorders of electrical stability of the heart in postinfarction cardiosclerosis

The effects of adaptation to intermittent and continuous hypoxia on the electrical stability of the heart were compared in middle altitude conditions and in altitude chamber in Wistar rats with postinfarction cardiosclerosis. It has been shown that both forms of adaptation could restore the heart fibrillation threshold and restrict the ectopic activity in postinfarction cardiosclerosis. Beneficial effects of adaptation to intermittent hypoxia in conditions of the altitude chamber appeared to be more radical.     

Morphology and Infraciliature of Three Species of Eutintinnus (Ciliophora; Tintinnina) with Guidelines for Interpreting Protargol-Stained Tintinnine Ciliates

ABSTRACT. The infraciliatures of three Chesapeake Bay species of Eutintinnus conforming in lorica morphology to E. angustatus, E. pectinis , and E. tenuis were compared following Protargol silver impregnation. The kinetome of these species had a number of shared attributes including: 1) a right and left field that were of similar length and kinetal spacing; 2) two, rarely three, long dorsal kineties composed of monokinetids; 3) a ventral kinety; and 4) the absence of a true posterior kinety. Nonetheless, the specific organization of infraciliary components varied considerably among species. For example, the organization of the ventral kinety and several kineties along the border of the left field was different in all three species. In addition, the dorsal kineties of E. angustatus differed positionally from those of E. pectinis and E. tenuis . Some divergence in oral infraciliature was also noted, with the arrangement of infundibular oral polykinetids in E. pectinis and E. tenuis being distinct from that of E. angustatus . The amount of variation in the infraciliature of Eutintinnus spp. was much greater than previously noted for congeneric species of tintinnines and supports the separation E. angustatus, E. pectinis , and E. tenuis at the generic or subgeneric level.     

Life cycle assessment tool for estimating net CO2 exchange of forest production

The study describes an integrated impact assessment tool for the net carbon dioxide (CO₂) exchange in forest production. The components of the net carbon exchange include the uptake of carbon into biomass, the decomposition of litter and humus, emissions from forest management operations and carbon released from the combustion of biomass and degradation of wood‐based products. The tool enables the allocation of the total carbon emissions to the timber and energy biomass and to the energy produced on the basis of biomass. In example computations, ecosystem model simulations were utilized as an input to the tool. We present results for traditional timber production (pulpwood and saw logs) and integrated timber and bioenergy production (logging residues, stumps and roots) for Norway spruce, in boreal conditions in Finland, with two climate scenarios over one rotation period. The results showed that the magnitude of management related emissions on net carbon exchange was smaller when compared with the total ecosystem fluxes; decomposition being the largest emission contributor. In addition, the effects of management and climate were higher on the decomposition of new humus compared with old humus. The results also showed that probable increased biomass growth, obtained under the changing climate (CC), could not compensate for decomposition and biomass combustion related carbon loss in southern Finland. In our examples, the emissions allocated for the energy from biomass in southern Finland were 172 and 188 kg CO₂ MW h^?1 in the current climate and in a CC, respectively, and 199 and 157 kg CO₂ MW h^?1 in northern Finland. This study concludes that the tool is suitable for estimating the net carbon exchange of forest production. The tool also enables the allocation of direct and indirect carbon emissions, related to forest production over its life cycle, in different environmental conditions and for alternative time periods and land uses. Simulations of forest management regimes together with the CC give new insights into ecologically sustainable forest bioenergy and timber production, as well as climate change mitigation options in boreal forests.     

The effect of growth rate and culturing conditions on the stability of plasmid pCJ55 and on the level of expression of a large fragment of DNA-polymerase I, cloned in Escherichia coli

Plasmid pCJ55 with a cloned gene for the large fragment of Escherichia coli DNA polymerase I is stable in the population of a recombinant strain under the conditions of batch and continuous cultivation at different dilution rates in the presence of ampicillin. The level of Klenow fragment expression is determined by at least two factors: the stability of the recombinant strain and its specific growth rate. The maximal activity of the Klenow fragment was found after thermoinduction of the culture growing at a rate of mu = 0.6 h-1 in a synthetic medium with bactopeptone and glucose as a carbon source.     

Development of polymorphic microsatellite markers in sesame (Sesamum indicum L.)

Fifty microsatellite sequences (SSRs) were isolated from an enriched library of sesame (Sesamum indicum L.) using a modified protocol. After screening, 10 polymorphic microsatellites were used to determine their usefulness in diversity analysis among 16 sesame accessions. The number of alleles ranged from three to six alleles per locus with an average of 4.6 alleles. The fragment size varied from 150 bp to 307 bp. Expected heterozygosites (H_E) and polymorphism information contents (PICs) ranged from 0.437 to 0.858 and 0.34 to 0.80, respectively, which indicates the highly informative nature of the microsatellites reported here. These microsatellite markers will be very useful in diversity analysis among a large germplasm collection of sesame present in our Korean gene bank and also in the establishment of its core collection.     

No regulatory role for adult predation in cyclic population dynamics of the autumnal moth,Epirrita autumnata

1. Multiannual population cycles of geometrid moths are thought to be driven by trophic‐level interactions involving a delayed density‐dependent component. Predation on adult moths has been a little‐studied mechanism of this phenomenon. 2. Using 29 daytime and 61 night‐time predation trials in the field, we exposed living autumnal moth (Epirrita autumnata Borkhausen, Lepidoptera: Geometridae) females to their natural predators during each autumn throughout the 10‐year population cycle. 3. In our northern study location (70°N), insectivorous passerines had already migrated, and harvestman Mitopus morio Fabricius (Opiliones: Phalangiidae) was found to be the main predator of the adult moths. The predation mortality occurred mainly at night and was positively correlated with the minimum temperature measured during the predation trial. 4. Despite high annual variability in the degree of adult predation, both direct and delayed density‐dependent effects were weak and indicate that predation on adult moths in the autumn does not have any regulatory role in cyclic population dynamics of the autumnal moth in northern Fennoscandia.     

Hot spots for nitrous oxide emissions found in different types of permafrost peatlands

Recent findings on large nitrous oxide (N₂O) emissions from permafrost peatlands have shown that tundra soils can support high N₂O release, which is on the contrary to what was thought previously. However, field data on this topic have been very limited, and the spatial and temporal extent of the phenomenon has not been known. To address this question, we studied N₂O dynamics in two types of subarctic permafrost peatlands, a peat plateau in Russia and three palsa mires in Finland, including also adjacent upland soils. The peatlands studied have surfaces that are uplifted by frost (palsas and peat plateaus) and partly unvegetated as a result of wind erosion and frost action. Unvegetated peat surfaces with high N₂O emissions were found from all the studied peatlands. Very high N₂O emissions were measured from peat circles at the Russian site (1.40±0.15 g N₂O m^?2 yr^?1). Elevated, sparsely vegetated peat mounds at the same site had significantly lower N₂O release. The N₂O emissions from bare palsa surfaces in Northern Finland were highly variable but reached high rates, similar to those measured from the peat circles. All the vegetated soils studied had negligible N₂O release. At the bare peat surfaces, the large N₂O emissions were supported by the absence of plant N uptake, the low C : N ratio of the peat, the relatively high gross N mineralization rate and favourable moisture content, together increasing availability of mineral N for N₂O production. We hypothesize that frost heave is crucial for high N₂O emissions, since it lifts the peat above the water table, increasing oxygen availability and making it vulnerable to the the physical processes that may remove the vegetation cover. In the future, permafrost thawing may change the distribution of wet and dry surfaces in permafrost peatlands, which will affect N₂O emissions.