Aerobic and anaerobic degradation of furan-3-carboxylate by Paracoccus denitrificans strain MK33

An organism identified as Paracoccus denitrificans was isolated from an enrichment culture with furan-3-carboxylate as its sole source of carbon and energy. The organism degraded furan-3-carboxylate under aerobic and — in the presence of nitrate - under anaerobic conditions. The aerobic degradation was initiated by an oxygenase reaction to form probably 2-hydroxy-3-furoate. Under anaerobic conditions the first intermediate was 3-furoyl-CoA which was reduced by NADPH to probably 4,5-dihydro-furoyl-CoA. Succinic semialdehyde was an intermediate in both aerobic and anaerobic mechanism of furan-3-carboxylate.Abbreviations F-3-C furan-3-carboxylate - 3-FCoA 3-furoyl-CoA     

Effects of SO2 on photosynthesis and ribulose bisphosphate carboxylase in pine tree seedlings

Fumigations of 4–7 week old seelings of Pinus silvestris , with ca 400 μg SO₂ m^-3 for 4–5 days resulted in a decrease both in net photosynthetic rate and in the levels of ribulose bisphosphate carboxylase activity of the primary needles. The effect on net photosynthesis was reversible. No visible damages were observed on the needles. Lower concentrations, ca 200 μg SO₂ m^-3, for ca 6 days inhibited net photosynthesis reversibly. The effect on net photosynthesis was not the result of stomata closure or of increased respiration. A dose-response relation for the inhibition of net photosynthesis and ribulose bisphosphate carboxylase is suggested. A similar relation was observed for the chlorophyll content of the needles. The reversible inhibition of photosynthesis was evident only at high quantum flux density, and the quantum yield of photosynthesis at rate limiting quantum flux was not affected. This was also suggested from an experiment with Scots pine in the field.     

Effects of bud removal in Scots pine (Pinus silvestris) seedlings

One- and two-“year”-old seedlings of Pinus silvestris L., from which the buds had been removed, were studied for five weeks during the second and third growth period, respectively. Intact seedlings were used as controls. The seedlings were cultivated under controlled conditions in a climate chamber. The growth of the seedlings was determined and the one-“year”-old needles assayed for changes in net photosynthesis and ribulose bisphosphate carboxylase activity and in the levels of protein, Kjeldahl nitrogen, chlorophyll and starch. In the control the carboxylase activity and the content of protein, Kjeldahl nitrogen and starch in the needles increased in the beginning of the “summer” and decreased during the shoot growth period. The starch content was higher after bud removal (decapitation), since the carbohydrate could not be utilized for the growth of the new shoot. Decapitation did not affect the growth rate of the roots. The content of Kjeldahl nitrogen and total and soluble protein in the needles was higher in the decapitated seedlings during the period of shoot elongation in the control. Total nitrogen, but not protein, reached high levels, indicating accumulation of non-protein compounds. The general course of the chlorophyll pattern was not affected. Higher ribulose bisphosphate carboxylase activity than in the control was observed in the later part of the experimental periods. The higher levels of protein and nitrogen as well as of carboxylase activity after decapitation support the interpretation that soluble protein, including the carboxylase, and possibly other nitrogen compounds in the older needles are used for growth of the shoot. The loss of protein and nitrogen and of carboxylase activity in the control did not seem to be due to mineral deficiency in the substrate. Despite higher levels of carboxylase activity and similar chlorophyll concentrations, light-saturated net photosynthesis was lower after decapitation. The ratio between photosynthesis and photorespiration was not affected.     

Nordic equiseticolous Pyrenomycetes

The Pyrenomycete flora on Equisetum has been studied, mainly on Nordic material. With regard to frequency and host specificity these fungi can be divided into three groups, viz. 1) true Equisetum fungi; 2) common species but not restricted to Equisetum; 3) accidental species. An annotated list is given of the two first categories which comprise the following taxa. 1: Didymosphaeria equiseti–hiemalis, Phaeosphaeria berlesei, P. equiseti, Mycosphaerella equiseti, M. equiseticola, Scirrhia castagnei, S. silvalica , and probably Didymella equisetina. 2: Phaeosphaeria eustoma, P. fuckelii, Mycosphaerella cf. aspidii.
Two new taxa and one new combination are published, viz. Phaeosphaeria equiseti (Karst.) L. & K. Holm comb, nov., P. equiseti var. lindii L. & K. Holm var. nov., Scirrhia silvalica L. & K. Holm sp. nov.     

Social interactions among breeding Brünnich's Guillemots Uria lomvia suggest constraints in relation to offspring vulnerability

Brünnich's Guillemots Uria lomvia are adapted to high-density breeding in large colonies on steep cliffs. Because they breed on narrow ledges, egg loss through dislodgement is an important cause of breeding failure. Fighting among breeders presumably raises the risk of accidental dislodgement. In this study, we investigated whether social behaviour among Brünnich's Guillemots shows any adaptations to reduce accidental egg loss by modifying behaviour during incubation. We found that the amount of aggression increased significantly at the time of hatching, perhaps in response to the reduced risk of breeding failure through dislodgement of a chick, compared with an egg. Allopreening followed an inverse trend, falling significantly after the day of hatch. This supports the hypothesis that allopreening is used to reduce aggressive interactions. At the same time, the frequency of allopreening was greatly increased on days when mosquitoes affected the birds, consistent with the hypothesis that allopreening is part of a defence strategy against ectoparasites.     

Biosorption of copper by yeasts

Summary The ability to accumulate copper from aqueous solutions was determined with different yeast species. Yeast cells did not show any significant differences in process kinetics. The uptake was very fast and was influenced by environmental factors. The metal-accumulating capacity differed among the tested strains. The yeastsCandida tropicalis andPichia guilliermondii were chosen for extensive research. Cells of the stationary growth phase were able to adsorb a high amount of copper. The uptake capacity decreased with increasing biomass concentration. Copper adsorption obeyed the Freundlich isotherm. Optimal pH range was between 5 and 7. The biomass could be used repeatedly for biosorption after desorption by mineral acids.     

Kinetics of lymphocyte stimulation in vitro by non-specific mitogens

The role of mitogens during lymphocyte activation was studied with kidney bean leucoagglutinin, concanavalin A and kidney bean phytohemagglutinin. The mitogens were removed by treatment with appropriate antisera, which was demonstrated to remove also mitogens already attached to the cells. The process of lymphocyte activation in vitro can be divided into four distinct steps, three of which are mitogen-dependent and the fourth is mitogen-independent. The first step consists of attachment of the stimulatory molecules to the cell membrane. The second step consists of reaction between mitogen and an activating system. During these two phases the cells become preactivated. The establishment of a preactivated state involves at least some synthesis of cytoplasmic RNA. The preactivated state is reversible and during the third step of lymphocyte activation the final result of preactivation is determined. Depending on the presence or absence of mitogen the cells may remain preactivated for over 60 h, they may return to the resting state or they may proceed through the final stages of the proliferation cycle and eventually divide. This fourth step is independent of the presence or absence of mitogen. A prolonged contact between cells and mitogen is required during the mitogen-dependent steps. The process of lymphocyte activation by mitogen is thus continuously being regulated by the stimulatory molecules on the lymphocyte membrane, which may be of considerable significance also for in vivo immunologicai reactions at the cellular level.     

Calcium dependency of the binding and mitogenicity of phytohemagglutinin: Differentiation between calcium-dependent and independent binding events

The same amount of phytohemagglutinin binds to lymphocytes at 37 °C and at 0 °C. The binding is inhibited by calcium chelators at 37 °C, but not at 0 °C, during the very first minutes of contact between lectin and cells. N-Acetylgalactosamine in high concentrations inhibits binding at both temperatures. The binding at 0 °C is abortive in the sense that it does not result in subsequent DNA synthesis. These findings indicate that the binding of phytohemagglutin (PHA) to the glycoprotein receptor on the cell surface does not in itself activate the immediate transducer of the mitogenic signal. The binding has to be accompanied by some change which involves calcium and occurs very rapidly, but cannot take place at 0 °C, to give a proper mitogenic anchorage of PHA to the cells.     

On the mechanism of action of 15-methyl-PGF2α as an abortifacient

Several hours following administration of long acting vaginal suppositories containing 3.0 mg of 15-methyl-PGF_2α for interruption of second trimester pregnancies there is an up to 10-fold increase in endogenous production of PGE₂ and PGF_2α before abortion as reflected by gas chromatographic-mass spectrometric determination of the major plasma metabolites of PGE₂ and PGF_2α. The data suggest that this increased formation of endogenous prostaglandins contributes to the induced uterine activity during the latter part of the abortion process.