Specific [3H] Glutamate Binding in the Cerebral Cortex and Hippocampus of Rats During Development: Effect of Homocysteine-Induced Seizures

Specific [³H]glutamate binding to synaptic membranes from the cerebral cortex and hippocampus of 7-, 12- and 18-day-old rats was examined, both in control animals and during seizures induced by homocysteine. In the cerebral cortex a transient peak of glutamate binding was observed in 7-day-old group, whereas in the hippocampus it occurred in 12-day-old animals. Total specific [³H]glutamate binding was not influenced by preceding seizure activity in either of the age groups and both the studied regions. NMDA- and QA-sensitive glutamate bindings represent the highest portion of the total binding. Moreover, NMDA-sensitive binding in the cerebral cortex of 7-day-old rats is significantly higher as compared to the two more mature groups. The proportion of individual receptor subtypes on total binding in each age group was not influenced by preceding seizure activity. However, NMDA-sensitive binding in the hippocampus of 12-day-old rats, sacrificed during homocysteine-induced seizures, was significantly increased as compared to corresponding controls. In contrast to the effect of NMDA, AMPA, kainate and quisqualate which displaced to a different extent [³H]glutamate binding, homocysteine had no effect when added to membrane preparations. Similarly, [³H]CPP and [³H]AMPA bindings were not affected in the presence of homocysteine. It thus seems unlikely that homocysteine is an effective agonist for conventional ionotropic glutamate receptors. Its potential activity at some of the modulatory sites at the NMDA receptor channel complex or at metabotropic receptors has to be clarified in further experiments.     

Surfactin production enhances the level of cardiolipin in the cytoplasmic membrane of Bacillus subtilis

Surfactin is a cyclic lipopeptide antibiotic that disturbs the integrity of the cytoplasmic membrane. In this study, the role of membrane lipids in the adaptation and possible surfactin tolerance of the surfactin producer Bacillus subtilis ATCC 21332 was investigated. During a 1-day cultivation, the phospholipids of the cell membrane were analyzed at the selected time points, which covered both the early and late stationary phases of growth, when surfactin concentration in the medium gradually rose from 2 to 84 μmol·l^− 1. During this time period, the phospholipid composition of the surfactin producer's membrane (Sf⁺) was compared to that of its non-producing mutant (Sf⁻). Substantial modifications of the polar head group region in response to the presence of surfactin were found, while the fatty acid content remained unaffected. Simultaneously with surfactin production, a progressive accumulation up to 22% of the stress phospholipid cardiolipin was determined in the Sf⁺ membrane, whereas the proportion of phosphatidylethanolamine remained constant. At 24 h, cardiolipin was found to be the second major phospholipid of the membrane. In parallel, the Laurdan generalized polarization reported an increasing rigidity of the lipid bilayer. We concluded that an enhanced level of cardiolipin is responsible for the membrane rigidification that hinders the fluidizing effect of surfactin. At the same time cardiolipin, due to its negative charge, may also prevent the surfactin-membrane interaction or surfactin pore formation activity.     

Olfactory Performance Is Predicted by Individual Sex-Atypicality,but Not Sexual Orientation

Many previous studies have reported robust sex differences in olfactory perception. However, both men and women can be expected to vary in the degree to which they exhibit olfactory performance considered typical of their own or the opposite sex. Sex-atypicality is often described in terms of childhood gender nonconformity, which, however, is not a perfect correlate of non-heterosexual orientation. Here we explored intrasexual variability in psychophysical olfactory performance in a sample of 156 individuals (83 non-heterosexual) and found the lowest odor identification scores in heterosexual men. However, when childhood gender nonconformity was entered in the model along with sexual orientation, better odor identification scores were exhibited by gender-nonconforming men, and greater olfactory sensitivity by gender-conforming women, irrespective of their sexual orientation. Thus, sex-atypicality, but not sexual orientation predicts olfactory performance, and we propose that this might not be limited to olfaction, but represent a more general phenomenon.     

Uranium,thorium and rare earth elements in macrofungi: what are the genuine concentrations?

Concentrations of uranium, thorium and rare earth elements (REE) in 36 species of ectomycorrhizal (26 samples) and saprobic (25 samples) macrofungi from unpolluted sites with differing bedrock geochemistry were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Analytical results are supported by use of certified reference materials (BCR-670, BCR-667, NIST-1575a) and the reliability of the determination of uranium was verified by epithermal neutron activation analysis (ENAA). It appears that data recently published on these elements are erroneous, in part because of use of an inappropriate analytical method; and in part because of apparent contamination by soil particles resulting in elevated levels of thorium and REE. Macrofungi from unpolluted areas, in general, did not accumulate high levels of the investigated metals. Concentrations of uranium and thorium were generally below 30 and 125 μg kg⁻¹ (dry weight), respectively. Concentrations of REE in macrofungi did not exceed 360 μg kg⁻¹ (dry weight) and their distribution more or less followed the trend observed in post-Archean shales and loess.     

Bathypelagic percid fry,a strongly predominating fry community in a deep European reservoir

The distribution, species composition, abundance and shoaling behaviour of young-of-year fish were studied in the canyon-shaped Vír Reservoir (Czech Republic) in mid-June 2010. Using the SIMRAD EK60 echosounder (frequency 120 kHz), fry were acoustically sampled along the longitudinal profile of the reservoir. A framed trawl was used simultaneously to collect fry in the open water. Apparent differences were found in the density of fry between the epipelagic, littoral and bathypelagic zones. Bathypelagic fry strongly predominated in the total fry community creating 95.3% while epipelagic and littoral fry contributed only 4.7%. The bathypelagic fry were represented by perch Perca fluviatilis (84.8%), zander Sander lucioperca (14.9%) and ruffe Gymnocephalus cernua (0.15%) and were observed all along the longitudinal profile of the reservoir creating a distinct layer on the echogram. The layer, composed of shoaling and non-shoaling fry individuals, reached its greatest depth in the Bay part of the reservoir (7.5–14.5 m) and it was rising in the water column towards the tributary. The situation that the bathypelagic percid fry predominate in the reservoir is absolutely unique and it is completely different from published observations from other canyon-shaped reservoirs where epipelagic percid fry prevailed.

     

POLYPHASIC CHARACTERIZATION OF THREE STRAINS OF ANABAENA RENIFORMIS AND APHANIZOMENON APHANIZOMENOIDES (CYANOBACTERIA) AND THEIR RECLASSIFICATION TO SPHAEROSPERMUM GEN. NOV. (INCL. ANABAENA KISSELEVIANA)1

Occurrences of rare cyanobacteria Anabaena reniformis Lemmerm. and Aphanizomenon aphanizomenoides (Forti) Horecká et Komárek were recently detected at several localities in the Czech Republic. Two monoclonal strains of An. reniformis and one strain of Aph. aphanizomenoides were isolated from distant localities and different sampling years. They were characterized by a combination of morphological, genetic, and biochemical approaches. For the first time, partial 16S rRNA gene sequences were obtained for these morphospecies. Based on this gene, all of these strains clustered separately from other planktonic Anabaena and Aphanizomenon strains. They appeared in a cluster with Cylindrospermopsis Seenaya et Subba Raju and Raphidiopsis F. E. Fritsch et M. F. Rich, clustered closely together with two An. kisseleviana Elenkin strains available from GenBank. A new generic entity was defined (Sphaerospermum gen. nov., with the type species S. reniforme, based on the traditional species An. reniformis). These results contribute significantly to the knowledge base about genetic heterogeneity among planktonic Anabaena–like and Aphanizomenon–like morphospecies. Accordingly, the subgenus Dolichospermum, previously proposed for the group of planktonic Anabaena, should be revaluated. Secondary metabolite profiles of the An. reniformis and Aph. aphanizomenoides strains differed considerably from 17 other planktonic Anabaena strains of eight morphospecies isolated from Czech water bodies. Production of puwainaphycin A was found in both of the An. reniformis strains. Despite the relatively short phylogenetic distance from Cylidrospermopsis, the production of cylindrospermopsin was not detected in any of our strains.     

Novel Television-Based Cognitive Training Improves Working Memory and Executive Function

The main study objective was to investigate the effect of interactive television-based cognitive training on cognitive performance of 119 healthy older adults, aged 60–87 years. Participants were randomly allocated to a cognitive training group or to an active control group in a single-blind controlled two-group design. Before and after training interactive television cognitive performance was assessed on well validated tests of fluid, higher-order ability, and system usability was evaluated. The participants in the cognitive training group completed a television-based cognitive training programme, while the participants in the active control group completed a TV-based programme of personally benefiting activities. Significant improvements were observed in well validated working memory and executive function tasks in the cognitive training but not in the control group. None of the groups showed statistically significant improvement in life satisfaction score. Participants'' reports of “adequate” to “high” system usability testify to the successful development and implementation of the interactive television-based system and compliant cognitive training contents. The study demonstrates that cognitive training delivered by means of an interactive television system can generate genuine cognitive benefits in users and these are measurable using well-validated cognitive tests. Thus, older adults who cannot use or afford a computer can easily use digital interactive television to benefit from advanced software applications designed to train cognition.     

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

Photothermal beam deflection together with photo-acoustic calorimetry and thermal grating belongs to the family of photothermal methods that monitor the time-profile volume and enthalpy changes of light induced conformational changes in proteins on microsecond to millisecond time-scales that are not accessible using traditional stop-flow instruments. In addition, since overall changes in volume and/or enthalpy are probed, these techniques can be applied to proteins and other biomacromolecules that lack a fluorophore and or a chromophore label. To monitor dynamics and energetics of structural changes associated with Ca²⁺ binding to calcium transducers, such neuronal calcium sensors, a caged calcium compound, DM-nitrophen, is employed to photo-trigger a fast (τ < 20 μsec) increase in free calcium concentration and the associated volume and enthalpy changes are probed using photothermal beam deflection technique.