Glial cells in the central nervous system of earthworm, Eisenia fetida

Glial elements in the central nervous system of Eisenia fetida were studied at light- and electron microscopic level. Cells were characterized with the aid of toluidine blue, Glial Fibrillary Acidic Protein (GFAP), S100 staining. We identified neurilemmal-, subneurilemmal-, supporting-nutrifying- and myelinsheath forming glial cells. Both neuronal and non-neuronal elements are S100-immunoreactive in the CNS. Among glial cells neurilemmal and subneurilemmal cells are S100-immunopositive. With the antibody against the S100 protein one band is visible at 15 kDa. GFA P-immunopositive supporting-nutrifying glial cells are localized around neurons and they often appear as cells with many vacuoles. GFA P-positive cell bodies of elongated neurilemmal glial cells are also visible. Western blot analysis shows a single 57 kDa GFA P immunoreactive band in the Eisenia sample. At ultrastructural level contacts between neuronal and glial cells are recognizable. Glial cell bodies and their filopodia contain a granular and vesicular system. Close contacts between neuronal cell membranes and glial filopodia create a special environment for material transport. Vesicles budding off glial cell granules move towards the cell membranes, probably emptying their content with kiss and run exocytosis. The secreted compounds in return may help neuronal survival, provide nutrition, and filopodia may also support neuronal terminals.     

Bacterial evolution of antibiotic hypersensitivity

The evolution of resistance to a single antibiotic is frequently accompanied by increased resistance to multiple other antimicrobial agents. In sharp contrast, very little is known about the frequency and mechanisms underlying collateral sensitivity. In this case, genetic adaptation under antibiotic stress yields enhanced sensitivity to other antibiotics. Using large‐scale laboratory evolutionary experiments with Escherichia coli, we demonstrate that collateral sensitivity occurs frequently during the evolution of antibiotic resistance. Specifically, populations adapted to aminoglycosides have an especially low fitness in the presence of several other antibiotics. Whole‐genome sequencing of laboratory‐evolved strains revealed multiple mechanisms underlying aminoglycoside resistance, including a reduction in the proton‐motive force (PMF) across the inner membrane. We propose that as a side effect, these mutations diminish the activity of PMF‐dependent major efflux pumps (including the AcrAB transporter), leading to hypersensitivity to several other antibiotics. More generally, our work offers an insight into the mechanisms that drive the evolution of negative trade‐offs under antibiotic selection.     

Photosynthetic activity of epilithic algal communities in sections of the Torna stream (Hungary) with natural and modified riparian shading

The photosynthetic activity of epilithon grown in the Torna-stream (Hungary) was studied. Samples were collected from natural sections with closed canopy and natural stream bed and from modified sections with trapezoid river bed and shores lacking riparian vegetation. We assumed that human modifications would have a significant impact on epilithic photosynthesis, and therefore expected to observe corresponding changes in photosynthesis–irradiance (P–I) parametric. The laboratory P–I measurements were carried out monthly between April 2008 and September 2009 with epilithon after 3 weeks of in situ colonization. The maximum rate of the photosynthesis (P _max) correlated positively with the chlorophyll a content of the samples. Natural sites had lower biomass and P _max values than modified sites, and the biomass differed substantially in spring and summer, the P _max differed significantly only in spring. Natural sections had higher biomass-specific photosynthesis values than modified sections in all seasons, but the difference was significant only in summer–autumn: in summer the samples from the natural sections had significantly higher photosynthetic efficiency. In spring and summer, the photoadaptation parameters (I _k ) of communities grown in modified sections were substantially higher than in natural sections. Light availability appeared to be the major factor regulating the seasonal photosynthetic activity of epilithic communities.     

Diversity of reed (Phragmites australis) stem biofilm bacterial communities in two Hungarian soda lakes

From reed biofilm samples of Kelemen-szék (Kiskunság National Park, KNP) and Nagy-Vadas (Hortobágy National Park, HNP) altogether 260 bacterial isolates were gained after serial dilutions and plating onto different media. Following a primary selection 164 strains were investigated by "traditional" phenotypic tests and clustered by numerical analysis. Fifty-six representative strains were selected to ARDRA and 16S rDNA sequence analysis for identification. Strains were identified as members of genera Agrobacterium, Paracoccus, Halomonas, Pseudomonas, Bacillus, Planococcus and Nesterenkonia. The species diversity was also investigated by a cultivation independent method. A clone library was constructed using the community DNA isolated from the biofilm sample of Kelemen-szék. Screening of the 140 bacterial clones resulted in 45 different ARDRA groups. Sequence analysis of the representatives revealed a great phylogenetic diversity. A considerable majority of the clones was affiliated with uncultured bacterial clones (with sequence similarity between 93 and 99%) originating from diverse environmental samples (for example salt marshes, compost or wastewater treatment plants). The DNA sequences of other clones showed the presence of genera Flavobacterium, Sphingobacterium, Pseudomonas and Agrobacterium.     

Pharmacological induction of ferritin prevents osteoblastic transformation of smooth muscle cells

Vascular calcification is a frequent complication of atherosclerosis, diabetes and chronic kidney disease. In the latter group of patients, calcification is commonly seen in tunica media where smooth muscle cells (SMC) undergo osteoblastic transformation. Risk factors such as elevated phosphorus levels and vitamin D₃ analogues have been identified. In the light of earlier observations by our group and others, we sought to inhibit SMC calcification via induction of ferritin. Human aortic SMC were cultured using β‐glycerophosphate with activated vitamin D₃, or inorganic phosphate with calcium, and induction of alkaline phosphatase (ALP) and osteocalcin as well as accumulation of calcium were used to monitor osteoblastic transformation. In addition, to examine the role of vitamin D₃ analogues, plasma samples from patients on haemodialysis who had received calcitriol or paricalcitol were tested for their tendency to induce calcification of SMC. Addition of exogenous ferritin mitigates the transformation of SMC into osteoblast‐like cells. Importantly, pharmacological induction of heavy chain ferritin by 3H‐1,2‐Dithiole‐3‐thione was able to inhibit the SMC transition into osteoblast‐like cells and calcification of extracellular matrix. Plasma samples collected from patients after the administration of activated vitamin D₃ caused significantly increased ALP activity in SMC compared to the samples drawn prior to activated vitamin D₃ and here, again induction of ferritin diminished the osteoblastic transformation. Our data suggests that pharmacological induction of ferritin prevents osteoblastic transformation of SMC. Hence, utilization of such agents that will cause enhanced ferritin synthesis may have important clinical applications in prevention of vascular calcification.     

The Effects of Temperature, Nitrogen, and Phosphorus on the Encystment of Peridinium cinctum, Stein (Dinophyta)

For avoiding the unfavorable environmental conditions several aquatic microorganisms are capable of forming specialized resistance cells like akinets, hypnospores, statospores, etc. Recognition of the important role of cysts in the life cycles of dinoflagellates increased the need to study their role in the ecology of phytoplanktons, and this, combined with the knowledge of chemical and biological characteristics of the water, may lead to a better understanding of the spatial and temporal dynamics of dinoflagellates. This paper reports on the effects of temperature, nitrogen, and phosphorus on the percentage of encystment of the dinoflagellate Peridinum cinctum Stein. The phosphorus content of the medium affected encystment only at the highest temperature applied (22 °C). Nitrogen content and temperature were the most important factors controlling the encystment.     

Autolytic hydrolases affect sexual and asexual development of <Emphasis Type="Italic">Aspergillus nidulans</Emphasis>

Radial growth, asexual sporulation, and cleistothecia formation as well as extracellular chitinase and proteinase formation of Aspergillus nidulans were monitored in surface cultures in order to study the physiological role of extracellular hydrolase production in carbon-stressed cultures. We set up carbon-stressed and carbon-overfed experimental conditions by varying the starting glucose concentration within the range of 2.5 and 40 g/L. Glucose starvation induced radial growth and hydrolase production and enhanced the maturation of cleistothecia; meanwhile, glucose-rich conditions enhanced mycelial biomass, conidia, and cleistothecia production. Double deletion of chiB and engA (encoding an extracellular endochitinase and a β-1,3-endoglucanase, respectively) decreased conidia production under carbon-stressed conditions, suggesting that these autolytic hydrolases can support conidia formation by releasing nutrients from the cell wall polysaccharides of dead hyphae. Double deletion of prtA and pepJ (both genes encode extracellular proteases) reduced the number of cleistothecia even under carbon-rich conditions except in the presence of casamino acids, which supports the view that sexual development and amino acid metabolism are tightly connected to each other in this fungus.     

Rhizome-associated bacterial communities of healthy and declining reed stands in Lake Velencei,Hungary

Lake Velencei is a shallow soda lake with extensive reed coverage. In this study, the bacterial communities of reed (Phragmites australis (Cav.) Trin. ex Steudel) rhizomes from healthy and declining stands were compared. Inner and outer rhizome surfaces were sampled. Samples were plated and isolated in September 1998 and June 1999. Phenotypic data of 371 bacterial strains were used for cluster analysis. Identification of phena was based on partial 16S rDNA sequence analysis of representative strains. Healthy reed stand rhizomes in fall 1998 were dominantly colonised by facultatively fermentative organisms, like Erwinia billingiae, Aeromonas sobria, Pantoea agglomerans, and Pseudomonas azotoformans. In the June 1999 sample, mainly Kocuria rosea and various Bacillus spp. dominated. In declining stands of September 1998, a saprotrophic community was found: Acinetobacter spp., Aeromonas hydrophila, Curtobacterium luteum, Agrobacterium vitis, and two further groups representing presumably new taxa. In June 1999, reed rhizomes were colonised by Kocuria rosea, but Dietzia maris and Bacillus cohnii could be isolated as well. Healthy and declining reed stand rhizomes can be distinguished based on the culturable bacterial community. No obligately plant pathogenic bacteria were found, however the possibility of a local, opportunistic bacterial invasion can not be ruled out (e.g. Curtobacterium). The presence of potentially beneficial bacterial species was demonstrated in the healthy reed rhizome rhizosphere (e.g. Pseudomonas azotoformans, Pantoea agglomerans).

     

Primary production of epipsammic algal communities in Lake Balaton (Hungary)

Benthic algal communities can play an important role in matter and energy flux of shallow lakes. Their contribution to total primary production of lakes has been largely unexplored. The aim of this study was to estimate the primary production of the epipsammic algal communities at different water depths in Lake Balaton (Hungary) with photosynthetic measurements performed in laboratory. The photosynthesis of the benthic algae of different origin was studied at nine different irradiance levels, in three replicates. The maximum photosynthetic rate (P _max) was always higher in samples from the shallow parts than those from the deeper regions of the lake. Along the west–east longitudinal axis of the lake P _max decreased in the southern part and increased in the middle of the lake as a consequence of differences in the chlorophyll-a concentrations. Knowing P _max, I _k, global radiation and extinction coefficient, the primary production (mg C m⁻² day⁻¹) of the epipsammic algal community was calculated at different water depths. In the shallow regions at 0.5 and 1 m water depth 75–95% and 60–85% of the production was attributable to the epipsammon. The percentage contribution of epipsammon was at 2 m water depth 20–65%. In the deeper pelagic region (>3 m) more than 85% of the primary production originated from the phytoplankton.     

Regional Grey Matter Structure Differences between Transsexuals and Healthy Controls—A Voxel Based Morphometry Study

Gender identity disorder (GID) refers to transsexual individuals who feel that their assigned biological gender is incongruent with their gender identity and this cannot be explained by any physical intersex condition. There is growing scientific interest in the last decades in studying the neuroanatomy and brain functions of transsexual individuals to better understand both the neuroanatomical features of transsexualism and the background of gender identity. So far, results are inconclusive but in general, transsexualism has been associated with a distinct neuroanatomical pattern. Studies mainly focused on male to female (MTF) transsexuals and there is scarcity of data acquired on female to male (FTM) transsexuals. Thus, our aim was to analyze structural MRI data with voxel based morphometry (VBM) obtained from both FTM and MTF transsexuals (n = 17) and compare them to the data of 18 age matched healthy control subjects (both males and females). We found differences in the regional grey matter (GM) structure of transsexual compared with control subjects, independent from their biological gender, in the cerebellum, the left angular gyrus and in the left inferior parietal lobule. Additionally, our findings showed that in several brain areas, regarding their GM volume, transsexual subjects did not differ significantly from controls sharing their gender identity but were different from those sharing their biological gender (areas in the left and right precentral gyri, the left postcentral gyrus, the left posterior cingulate, precuneus and calcarinus, the right cuneus, the right fusiform, lingual, middle and inferior occipital, and inferior temporal gyri). These results support the notion that structural brain differences exist between transsexual and healthy control subjects and that majority of these structural differences are dependent on the biological gender.