CONTENTS & ABSTRACTS
In English. Summaries in Estonian
Proceedings of the Estonian Academy of Sciences.
Volume 50 No. 1 March 2001
Editorial; 3–4(full article in PDF format)
Changes in the texture and exchange properties of skeletal quarry detritus under forest during thirty years; 5–13(full article in PDF format)
Abstract. Areas of former open-cast oil-shale mines afforested about 30 years ago were studied at Sirgala, NE Estonia. Synchronously with the development of high productivity pine stands, a rapid progress of Calcaric Regosol has taken place on pure skeletal (450–650 g kg–1 of skeleton) quarry detritus. Organic carbon of the R2O3-humic-fulvic forest humus of litter and root origin amounts to 28 ± 6 g kg–1 in the epipedon formed and to 13 ± 3 g kg–1 in the transitional AC-horizon. The proportion of humus compounds bound with clay and immobile sesquioxides is also significant. Forest humus is active and the soluble fractions make up 60–80% of total organic carbon. Interactions between the formed humus and the mineral stratum of detritus have resulted in the weathering of stone, gravel, and sand fractions and in the accumulation of clay in the epipedon and of silt in the transitional horizon. Subsequent physical and further chemical weathering, progressing in depth, are characteristic of any fraction. The territorial (site) variability of changes in texture is lower than in the composition of organic pedogenetic agents. Ca2+ forms more than 80% of base exchangeable capacity, the proportion of Mg2+ being highly variable. Humus colloids are prevalent in the exchange complex although the formed clay is also important.
Key words: quarry detritus, primary pedogenesis, soil texture, exchangeable properties, Calcaric Regosol.
Distribution of mysids on bank slopes in the Gulf of Riga; 14–21(full article in PDF format)
Ilmar KOTTA and Jonne KOTTA
Abstract. The abundance and biomass distribution of mysids were estimated on two bank slopes of the Gulf of Riga in 1977–80. The distribution of mysids was aggregated and related to the temperature conditions. Higher densities of mysids coincided with the areas where the thermocline boundaries touched the sea floor. In these biotopes with strong temperature gradients mysids were often observed outside of their natural temperature preferences. Mysis relicta was recorded above the thermocline at 10 ºC and Neomysis integer below the thermocline at 2 ºC.
Key words: Mysis, Neomysis, frontal zone, Baltic.
The effect of cytokinin type and concentration and the number of subcultures on the multiplication rate of some decorative plants; 22–32(full article in PDF format)
Rael VARDJA and Tõnis VARDJA
Abstract. Long-term micropropagation of some plants by tissue culture was investigated. The plants studied can be divided into three groups according to their sensitivity to cytokinins benzyladenine (BA) and kinetin (K). (1) Plants (gerbera cultivars) whose multiplication on BA media is not recommended. Permanent high K level must also be avoided. It must be decreased gradually during a long-term culture. After the 8th or 9th subculture the shoots are to be transferred to the resting medium with 0.1 mg/L K and 1.0 mg/L indoleacetic acid. (2) Plants (Cordyline, Dracaena, Dieffenbachia) that may be multiplied on media containing either BA or K, the latter being preferable as its concentration may be varied within a larger range (0.5–4 mg/L) without negative side effects. (3) Plants (Philodendron, Spathiphyllum, Musa) that may be multiplied on BA media without even relatively high BA concentrations (5 mg/L) leading to vitrification. However, in order to obtain the best shoots for rooting, the BA content of the multiplication media has to be reduced to 1/2–1/3 of its original value after the 5th or 6th subculture.
Key words: decorative plants, tissue culture, long-term micropropagation, cytokinins.
Sensitivity of platelets to prostaglandins in patients with coronary artery disease; 33–36(full article in PDF format)
Vilja MARDLA, Gennadi KOBZAR, Indrek RÄTSEP, Madis LÕHMUS, Ivar JÄRVING, and Nigulas SAMEL
Abstract. The platelet sensitivity to the antiaggregatory prostaglandins (PGE1, 13,14-dihydro-PGE1, and 5,6-dihydro-PGE3) was studied in patients with coronary artery disease. Platelets of healthy subjects were used as control. The sensitivity was tested in vitro by inhibiting the adenosine diphosphate-induced platelet aggregation with these prostaglandins of various concentrations. In the patients the antiaggregatory potency of the prostaglandins was significantly lower than in healthy subjects.
Key words: platelets, prostaglandins, coronary artery disease.
Land snails in an afforested oil-shale mining area; 37–41(full article in PDF format)
Raivo MÄND, Annelie EHLVEST, and Piret KIRISTAJA
Abstract. The numbers and species richness of land snails in four (8, 13, 23, and 25 years old) neighbouring pine plantations in an afforested oil-shale mining area were studied. No snails were found in the eight-year-old plantation. In the 13-year-old plantation two species occurred, but the density of individuals was quite low. In the 25-year-old plantation nine snail species were registered. The degree of species richness in older than 20 years pine plantations of the former oil-shale mining area was the same as that in the most base-rich deciduous forests of West-Estonian large islands, while the density of individuals was even higher. Since land snails serve as a very important calcium source for many birds, former oil-shale mining areas may easily turn into far more bird-rich habitats than are most other Estonian pine forests.
Key words: land snails, calcium, afforestation, former mining area, pine plantations.
Estonian Academy of Sciences: Meeting the challenges for 2000–2004.
Framework af activities; 42–43