Experimental evidence for parasite‐induced over‐winter mortality in juvenile Rhodeus amarus

In this study, the effects of the eye fluke Diplostomum pseudospathaceum (Trematoda) infection on over‐winter survival of young‐of‐the‐year (YOY) European bitterling Rhodeus amarus (Cyprinidae) were examined between September 2010 and April 2011. The fish were reared in semi‐natural conditions to ensure that results were not confounded by other parasite infections. The cumulative mortality of R. amarus from November until April was significantly higher in D. pseudospathaceum‐infected fish (57·3%) compared to controls (42·1%). Infection of the parental generation did not have any effect on the mortality of juveniles. The results indicate that D. pseudospathaceum infection increases over‐winter mortality of YOY R. amarus. The possible mechanisms causing mortality are discussed.     

Activation of protein kinase C suppresses fragmentation of pig oocytes aged in vitro

When cultured for an extended time, pig oocytes that matured in vitro to the stage of metaphase II undergo the complex process designated as ageing. Under our conditions, some pig oocytes aged 3 days remained at the stage of metaphase II (22%), but others underwent spontaneous parthenogenetic activation (45%), and still others perished through fragmentation (28%) or lysis (5%). Activation of protein kinases C (PKCs) using phorbol-12-myristate-13-acetate (PMA) protects oocytes from fragmentation. None of the oocytes were fragmented after 3 days of aging in 50 nM of PMA. A similar effect (8% of fragmented oocytes) was observed after a 3-day treatment of aging oocytes with 100 μM of 1-stearoyl-2arachidonoyl-sn-glycerol (STEAR). PMA and STEAR activate both calcium-dependent and calcium-independent PKCs. This combined effect on PKCs seems to be essential for the protection of oocytes from fragmentation. Neither the specific activator of calcium-dependent PKCs 1-oleoyl-2-acetyl-sn-glycerol (OLE) nor the specific activator of calcium-independent PKCs dipalmitoyl-l-α-phosphatidylinositol-3,4,5-triphosphate heptaammonium salt (DIPALM) suppressed the fragmentation of aging pig oocytes. Twenty-one percentage of oocytes fragmented when aged for 3 days in 10 μM OLE and 26% of aged oocytes fragmented in 100 nM of DIPALM. However, fragmentation was significantly suppressed to 7% when the oocytes were exposed to the combination of both 10 μM OLE and 100 nM DIPALM. Aging pig oocytes cultured for 1 day with PMA maintained a high capability of being parthenogenetically activated (86% of activated oocytes), using calcium ionophore with 6-dimethylaminopurine. Ageing oocytes treated with PMA also had high capability of cleavage (82%) after their artificial parthenogenetic activation. However, their ability to develop to the stage of blastocyst (12%) was suppressed when compared with oocytes activated immediately after their maturation (29%).     

In vitro reactivation of sarin-inhibited brain acetylcholinesterase from different species by various oximes

In vitro as well as in vivo evaluation of the reactivating efficacy of various oximes against nerve agent-inhibited acetylcholinesterase has been usually done with the help of animal experiments. Nevertheless, previously published data indicate that the reactivation potency of oximes may be different in human and animal species, which may hamper the extrapolation of animal data to human data. Therefore, to better evaluate the efficacy of various oximes (pralidoxime, obidoxime, HI-6, K033) to reactivate brain acetylcholinesterase inhibited by sarin by in vitro methods, human, rat and pig brain acetylcholinesterase were used to calculate kinetic parameters for the reactivation. Our results show differences among the species, depending on the type of oxime, and indicate that data from animal experiments needs to be carefully evaluated before extrapolation to humans.     

Isolation and characterization of wheat peroxidase isoenzyme B1

Two pure peroxidase isoenzymes B1 and D4 were isolated from the upper parts of 10-day-old wheat seedlings by means of gel and ion-exchange chromatography. Their MWs were 85000 and 24000 respectively. B1 was unstable and under various conditions it was converted to another isoenzyme, electrophoretically identical with D4. B1 contains about 40% of neutral sugars: 17.2% arabinose, 15.3% galactose, 5% glucose and traces of mannose. D4 is free of neutral sugars. None of the isoenzymes contained amino sugars. B1 oxidizes ferulic and p-coumaric acids. This oxidation has two pH optima of 4.4 and 5.4–5.6 and is inhibited by high concentrations of substrates, cyanide and azide. B1 oxidizes IAA in the presence of phenolic cofactor and Mn²⁺ ions. IAA oxidation has two pH optima of 4.5 and 5.6 and is inhibited by high substrate concentration, cyanide and azide, and by a number of indole derivatives. The main products of IAA oxidation are 3-methyleneoxindole and indole-3-methanol. o- and p- diphenols induce a lag period prior to IAA oxidation. Ferulic acid is oxidized during this lag period, probably to a dimer. B1 is able to produce H₂O₂ from oxygen. Mn²⁺ ions, a phenolic cofactor and an electron donor (IAA or NADH) are needed. B1 oxidizes α-keto-γ- methylmercaptobutyric acid to ethylene. D4 has a low peroxidatic activity and is inactive as an IAA oxidase. Thus B1 is probably an active cell wall-bound peroxidase isoenzyme, whereas D4 is its decomposition product.     

Isolation and sequence analysis of the genomic DNA fragment encoding an aspartic proteinase inhibitor homologue from potato (Solanum tuberosum L.)

A genomic DNA clone encoding an aspartic proteinase inhibitor of potato was isolated from a lambda EMBL3 phage library using the aspartic proteinase inhibitor cDNA as a hybridization probe. The gene has all characteristic sequences normally found in eucaryotic genes. Typical CAAT and TATA box sequences were found in the 5-upstream region. In this part are also two putative regulatory AGGA box sequences located. In the genomic sequence there are no intron sequences interrupting the coding region. An open reading frame of the gene encodes a precursor protein of 217 amino acids which shows high percent identity with the aspartic proteinase inhibitor cDNA.     

From Mesolithic hunters to Iron Age herders: a unique record of woodland use from eastern central Europe (Czech Republic)

Vegetation History and Archaeobotany - In a continuous, perfectly stratified sedimentary sequence which was discovered under a large sandstone overhang in northern Bohemia, Czech Republic, we...     

Photosynthesis of Cockspur [Echinochloa crus-galli (L.) Beauv.] at Sites of Naturally Elevated CO2 Concentration

High abundance of cockspur (Echinochloa crus-galli) at the geothermal carbon dioxide spring area in Staveinci indicates that this species is able to grow under widely varying CO₂ concentrations. Living cockspur plants can even be found very close to gas-releasing vents where growth is significantly reduced. Plant height correlated well with CO₂ exposure. The ¹³C value of the CO₂ spring air was –3.9 and ¹³C values of high-, medium-, and low-CO₂ plants were –10.14, –10.44, and –11.95 , respectively. Stomatal response directly followed the prevailing CO₂ concentrations, with the highest reduction of stomatal conductance in high CO₂ concentration grown plants. Analysis of the curves relating net photosynthetic rate to intercellular CO₂ concentration (P _N-C_i curves) revealed higher CO₂ compensation concentration in plants growing at higher CO₂ concentration. This indicates adjustment of respiration and photosynthetic carbon assimilation according to the prevailing CO₂ concentrations during germination and growth. There was no difference in other photosynthetic parameters measured.     

Soil chemical properties affect the concentration of elements (N,P, K,Ca, Mg,As, Cd,Cr, Cu,Fe, Mn,Ni, Pb,and Zn) and their distribution between organs of Rumex obtusifolius

Background and aims

The ionome (elemental composition) of grassland species has rarely been studied at the level of individual organs and little is known about effects of soil chemical properties on the ionome. Using the model oxalate plant Rumex obtusifolius, we asked how its biomass production and the distribution of elements between its organs is affected by soil chemical properties.

Methods

We established a pot experiment with R. obtusifolius planted in acidic non-contaminated control and in slightly acidic and alkaline soils anthropogenically contaminated by the risk elements As, Cd, Pb, and Zn. Both contaminated soils were untreated and treated by lime and superphosphate. We determined biomass production and the concentrations of elements in its organs.

Results

Biomass production was negatively related to the mobility of micro- and risk elements. Restricted transport of micro- and risk elements from belowground organs into leaves was recorded in untreated contaminated soils. In both lime-treated soils and in superphosphate-treated alkaline soil, elevated transport of micro- and risk elements from belowground organs into leaves was recorded in comparison to untreated contaminated soils. The lowest concentrations of micro- and risk elements were recorded in stems and seeds, followed by belowground organs and leaves.

Conclusions

R. obtusifolius is an As-, Cd-, Pb-, and Zn-excluder and is sensitive to high availability of micro- and risk elements in the soil. Soil chemical properties affect the distribution of essential elements within the plant greatly.