Planktonic bacterial community composition of an extremely shallow soda pond during a phytoplankton bloom revealed by cultivation and molecular cloning

Böddi-szék is one of the shallow soda ponds located in the Kiskunság National Park, Hungary. In June 2008, immediately prior to drying out, an extensive algal bloom dominated by a green alga (Oocystis submarina Lagerheim) was observed in the extremely saline and alkaline water of the pond. The aim of the present study was to reveal the phylogenetic diversity of the bacterial communities inhabiting the water of Böddi-szék during the blooming event. Using two different selective media, altogether 110 aerobic bacterial strains were cultivated. According to the sequence analysis of the 16S rRNA gene, most of the strains belonged to alkaliphilic or alkalitolerant and moderately halophilic species of the genera Bacillus and Gracilibacillus (Firmicutes), Algoriphagus and Aquiflexum (Bacteroidetes), Alkalimonas and Halomonas (Gammaproteobacteria). Other strains were closely related to alkaliphilic and phototrophic purple non-sulfur bacteria of the genera Erythrobacter and Rhodobaca (Alphaproteobacteria). Analysis of the 16S rRNA gene-based clone library indicated that most of the total of 157 clone sequences affiliated with the anoxic phototrophic bacterial genera of Rhodobaca and Rhodobacter (Alphaproteobacteria), Ectothiorhodospira (Gammaproteobacteria) and Heliorestis (Firmicutes). Phylotypes related to the phylum Bacteroidetes formed the second most abundant group. Clones related to the mainly anaerobic and alkaliphilic bacterial genera of Anoxynatronum (Firmicutes), Spirochaeta (Spirochaetes) and Desulfonatronum (Deltaproteobacteria) were also abundant. Further clone sequences showed less than 95 % similarity values to cultivated species of the phyla Actinobacteria, Cyanobacteria, Deinococcus-Thermus, Fibrobacteres, Gemmatimonadetes and Lentisphaerae.     

High level functional expression of the ABCG2 multidrug transporter in undifferentiated human embryonic stem cells

Expression of multidrug resistance ABC transporters has been suggested as a functional marker and chemoprotective element in early human progenitor cell types. In this study we examined the expression and function of the key multidrug-ABC transporters, ABCB1, ABCC1 and ABCG2 in two human embryonic stem (HuES) cell lines. We detected a high level ABCG2 expression in the undifferentiated HuES cells, while the expression of this protein significantly decreased during early cell differentiation. ABCG2 in HuES cells provided protection against mitoxantrone toxicity, with a drug-stimulated overexpression of the transporter. No significant expression of ABCB1/ABCC1 was found either in the undifferentiated or partially differentiated HuES cells. Examination of the ABCG2 mRNA in HuES cells indicated the use of selected promoter sites and a truncated 3' untranslated region, suggesting a functionally distinct regulation of this transporter in undifferentiated stem cells. The selective expression of the ABCG2 multidrug transporter indicates that ABCG2 can be applied as a marker for undifferentiated HuES cells. Moreover, protection of embryonic stem cells against xenobiotics and endobiotics may depend on ABCG2 expression and regulation.     

Correlative morphometric and electrochemical measurements of serotonin content in earthworm muscles

Distribution of serotonin (5-HT) content of nervous fibers in both the somatic and the visceral muscle of Eisenia fetida have been investigated using immunocytochemical staining and voltammetric measurements. The somatic muscles in the body wall are richer innervated with serotoninergic fibers than the visceral ones in the pharynx and gizzard. The relative density of immunopositive fibers in the circular muscle layer of the body wall was found to be 2.73% while in the prostomium it was 1.02%. In the case of the muscle in pharynx 1.12% and in gizzard 1.28% density values were found. Differential Pulse Voltammetric (DPV) measurements with carbon fiber electrodes in the above mentioned muscle layers gave 272.5 nA, 135.0 nA, 122.5 nA, 137.5 nA peak heights, respectively. In the statistical analysis T-test was used at a confidence level of 95% (p<0.05). DPV current peak (i(p)) values reflect clearly the 5-HT concentration differences. Significant correlation was found between the innervation density and the i(p) values recorded in different areas. The i(p) values recorded at different times in different locations are determined by instantaneous serotonin concentration of the living tissue. As far as we know this is the first report using in vivo voltammetry investigating serotonin content in earthworm, E. fetida.     

Behavioral specificity of non-genomic glucocorticoid effects in rats: effects on risk assessment in the elevated plus-maze and the open-field

The rapid effects of glucocorticoids on various behaviors suggest that these hormones play a role in rapidly coping with challenging situations. The variety of behaviors affected in different situations raise, however, questions regarding the specificity and roles of glucocorticoids in controlling behavior. To clarify this issue, we assessed the rapid behavioral effects of glucocorticoids in the elevated plus-maze (EPM) and the open-field (OF) tests in male rats. Both tests measure three different kinds of behavioral responses: locomotion, anxiety-like behaviors (central area and open arm exploration in the OF and EPM tests, respectively), and risk assessment (investigating aversive areas in a stretched attend posture). The acute inhibition of glucocorticoid synthesis by metyrapone decreased risk assessment but did not affect locomotion and anxiety-like behaviors. Corticosterone administration increased risk assessment, without affecting locomotion and anxiety-like behaviors. Moreover, plasma corticosterone levels measured immediately after testing strongly correlated with the intensity of risk assessment. The effects of corticosterone were rapid, as occurred even when the hormone was injected 2 min before behavioral testing. In addition, the effect was resistant to protein synthesis inhibition. These data demonstrate that glucocorticoids are able to increase specifically risk assessment behaviors by non-genomic mechanisms in two different, novelty-related, non-social challenging situations. Thus, glucocorticoids appear to rapidly induce specific behavioral adjustments to meet immediate requirements set by the challenge. These data support earlier assumptions on the role of glucocorticoids in coping, and it can be hypothesized that the rapid activation of the HPA-axis may play a role in forming coping responses.     

First record of picophytoplankton diversity in Central European hypersaline lakes

Our survey has revealed that the phytoplankton in the anthropo-hypersaline lakes of the Transylvanian Basin (Romania) was often dominated by photoautotrophic picoplankton (PPP, cells with a diameter <2?μm). Therefore, the aim of this study was to identify PPP members both in the summer and the winter communities using molecular biological techniques, denaturing gradient gel electrophoresis (DGGE) and sequence analysis. The applied PCR-DGGE methods were highly specific to cyanobacteria and green algae. A total of 11 different plankton taxa were identified that were related to several distant taxonomic groups. PPP were represented by a simple community and consisted of two major genotypes, one from the green algal species Picochlorum oklahomense and the other related to marine Synechococcus isolates (Cyanobacteria). These marine PPP species were recorded for the first time in inland saline lakes from Europe. Besides picoplankton, several additional marine taxa (e.g. cryptophytes and haptophytes) were detected among the nanoplankton species. The presence of the identified marine and hypersaline species could be explained by wind, precipitation or waterfowl transfer; however, this latter could have smaller importance.     

Pseudodioon akyoli gen. et sp. nov., an extinct member of Cycadales from the Turkish Miocene

Fossil cycadalean leaves recorded from the Miocene plant assemblage of Soma, western Turkey, are described and assigned to an extinct genus and species, Pseudodioon akyoli. Leaf macromorphology suggests affinity with members of the Zamiaceae (subfam. Encephalartoideae), particularly with modern Dioon. Micromorphological features on the other hand indicate affinity with modern Cycas (Cycadaceae). Ordinary cells on the adaxial epidermis are isodiametric and are not differentiated into thick- and thin-walled cells. This is similar to Encephalartoideae-like fossils reported from the Cenozoic of the Northern Hemisphere, and even from the Mesozoic. Shared macromorphological traits of P. akyoli and other coeval Encephalartoideae-like fossil cycadalean leaves from Europe suggest that an extinct group of cycads inhabited southern Europe from the western part of Turkey, through Greece and France to Switzerland in the north during the Oligo-Miocene.     

Oligotrophication of Lake Balaton over a 20-year period and its implications for the relationship between phytoplankton and zooplankton biomass

Hydrobiologia - Lake Balaton, the largest lake in Central Europe, underwent severe eutrophication from the 1960s to the 1990s, due to phosphorus loadings from external anthropogenic sources. The...