J-binding protein increases the level and retention of the unusual base J in trypanosome DNA

The nuclear DNA of Trypanosoma brucei and other kinetoplastid flagellates contains the unusual base beta-d-glucosyl-hydroxymethyluracil, called J, replacing part of the thymine in repetitive sequences. We have described a 100 kDa protein that specifically binds to J in duplex DNA. We have now disrupted the genes for this J-binding protein (JBP) in T. brucei. The disruption does not affect growth, gene expression or the stability of some repetitive DNA sequences. Unexpectedly, however, the JBP KO trypanosomes contain only about 5% of the wild-type level of J in their DNA. Excess J, randomly introduced into T. brucei DNA by growing the cells in the presence of the J precursor 5-hydroxymethyldeoxyuridine, is lost by simple dilution as the KO trypanosomes multiply, showing that JBP does not protect J against removal. In contrast, cells containing JBP lose excess J only sluggishly. We conclude that JBP is able to activate the thymine modification enzymes to introduce additional J in regions of DNA already containing a basal level of J. We propose that JBP is a novel DNA modification maintenance protein.     

Short-term plasticity at the calyx of held

Synapses show widely varying degrees of short-term facilitation and depression. Several mechanisms have been proposed to underlie short-term plasticity, but the contributions of presynaptic mechanisms have been particularly difficult to study because of the small size of synaptic boutons in the mammalian brain. Here we review the functional properties of the calyx of Held, a giant nerve terminal that has shed new light on the general mechanisms that control short-term plasticity. The calyx of Held has also provided fresh insights into the strategies used by synapses to extend their dynamic range of operation and preserve the timing of sensory stimuli.     

Long-term adaptation of methanol-fed thermophilic (55 °C) sulfate-reducing reactors to NaCl

A laboratory-scale upflow anaerobic sludge bed (UASB) reactor was operated during 273 days at increasing NaCl concentrations (0.5–12.5 g NaCl l^–1) to assess whether the stepwise addition of the salt NaCl results in the acclimation of that sludge. The 6.5-l thermophilic (55 °C), sulfidogenic [a chemical oxygen demand (COD) to SO₄^2– ratio of 0.5] UASB reactor operated at an organic loading rate of 5 g COD l^–1 day^–1, a hydraulic retention time of 10 h and was fed with methanol as the sole electron donor. The results show that the adaptation of the thermophilic, sulfidogenic methanol-degrading biomass to a high osmolarity environment is unlikely to occur. Sulfide was the main mineralization product from methanol degradation, regardless of the NaCl concentration added to the influent. However, sulfide production in the reactor steadily decreased after the addition of 7.5 g NaCl l^–1, whereas acetate production was stimulated at that influent NaCl concentration. Batch tests performed with sludge harvested from the UASB reactor when operating at different influent salinities confirmed that acetate is the main metabolic product at NaCl concentrations higher than 12.5 g l^–1. The apparent order of NaCl toxicity towards the different trophic groups was found to be: sulfate-reducing bacteria > methane-producing archaea > acetogenic bacteria.     

Outcome study: periareolar mammaplasty patients' perspective

Residual scars on occasion compromise patient satisfaction with breast reduction procedures. Periareolar breast reduction was proposed to minimize the scarring produced by the operation. This technique was criticized predominantly for producing a breast with low projection, for recurrence of ptosis after surgery, and for widening of the periareolar scar. The purpose of this study was to evaluate patient satisfaction from this technique. In the first branch of the study, 11 patients who had periareolar or circumareolar breast reduction were compared with 13 patients who had vertical scar reduction mammaplasty. The groups were matched for patient's age, size of reduction, and follow-up period. The patients were contacted by phone and requested to comment on four aspects of their operation: breast size, symmetry, quality of scars, and appearance and position of the nipple-areola complex. The replies were converted to numerical values and analyzed statistically. A panel of three women, prospective patients for breast reduction, were presented with standardized five-view before-and-after photographs and requested to score the results using the same criteria. Their responses were analyzed in the same manner. Both phases of the study produced similar results. Breast reduction done through a periareolar scar scored higher than a vertical scar technique. The operation did not differ with respect to shape, symmetry, or nipple-areola shape but did with respect to dissatisfaction with scars, which affected the overall result. This experimental model of assessing results of cosmetic operations is proposed as a tool to assess the patient's rather than the surgeon's perspective of a surgical technique, and it could find application in assessing other cosmetic operations.     

Diffusional properties of methanogenic granular sludge: 1H NMR characterization

The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22 degrees C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H(2)O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H(2)O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55 degrees C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10 degrees C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90 degrees C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl(2) did not affect the H(2)O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors.     

Effects of emotion-oriented care on elderly people with cognitive impairment and behavioral problems in residential homes

This study investigates the effects of emotion-oriented care on the behavior of elderly people with cognitive impairment and behavioral problems. This approach is mainly based on the validation approach, but uses also insights from other approaches like reminiscence and sensory stimulation. Sixteen homes for the aged with structured day care units were randomly allocated to an intervention or control group. 151 Residents with cognitive impairment and behavioral problems were included in the study. The eight intervention homes received a training program with regard to emotion-oriented care. In the eight control homes usual care was continued. Measurements were performed at baseline and after three, six and twelve months of follow-up (assessment by caregivers and relatives). The primary outcome measure was the change in behavior of the residents. The results of multilevel analyses (overall, subgroup and per protocol) showed no statistically significant, nor clinically relevant effects in favor of the intervention group on the behavioral outcome measures. A possible reason for this is that the intervention did not result in significant contrast between the study groups. There is insufficient scientific evidence yet to justify the implementation of emotion-oriented care in residential homes, for residents with moderate to severe cognitive impairment and behavioral problems, on a large scale. Additional studies are needed in which special attention should be given to the implementation process.     

Plasticity and canalization in the control of reproduction in the lubber grasshopper

The ability to change reproductive tactics during adult developmentin response to environmental variation is predicted to enhancefitness. Many organisms show phenotypic plasticity early innon-embryonic development, but later exhibit phases of developmentalinflexibility (=canalization). Therefore, we studied reproduction-relatedhormones and proteins and their relationships to plasticityin the Eastern lubber grasshopper. Diet-switching experimentsdemonstrated plasticity early in the egg production cycle, buta switch to canalization late in the cycle. We measured developmentaltiters of 4 hemolymph compounds from single individuals fromadult molt until first oviposition. These 4 compounds were theegg-yolk precursor protein vitellogenin, juvenile hormone (thecentral regulator of insect reproduction), major hemolymph proteins,and ecdysteroids (the arthropod molting hormone that ultimatelyis stored in the egg). Using diet manipulations, we investigatedhow these developmental titers relate to the switch from plasticto canalized egg production. All 4 hemolymph compounds reachedtheir peak levels during the canalized phase, about 12 day beforeoviposition. Diet switches after these peak levels did not affectthe timing to oviposition. Therefore, these peak titers werephysiological events that occurred after the individual committedto laying. We compared these patterns in reproduction to thedevelopment toward adult molt, another major life-history eventin insects. We observed an extended canalized phase before theadult molt. This canalized phase always included a peak of ecdysteroids.The similar patterns in the physiology of these life-historyevents suggested that common limitations may exist in majordevelopmental processes of insects that are directed by hormones.     

Biological reduction of nitric oxide in aqueous Fe(II)EDTA solutions

The reduction of nitric oxide (NO) in aqueous solutions of Fe(II)EDTA is one of the core processes in BioDeNOx, an integrated physicochemical and biological technique for NO(x)() removal from industrial flue gases. NO reduction in aqueous solutions of Fe(II)EDTA (20-25 mM, pH 7.2 +/- 0.2) was investigated in batch experiments at 55 degrees C. Reduction of NO to N(2) was found to be biologically catalyzed with nitrous oxide (N(2)O) as an intermediate. Various sludges from full-scale denitrifying and anaerobic reactors were capable to catalyze NO reduction under thermophilic conditions. The NO reduction rate was not affected by the presence of ethanol or acetate. EDTA-chelated Fe(II) was found to be a suitable electron donor for the biological reduction of nitric oxide to N(2), with the concomitant formation of Fe(III)EDTA. In the presence of ethanol, EDTA-chelated Fe(III) was reduced to Fe(II)EDTA. This study strongly indicates that redox cycling of FeEDTA plays an important role in the biological denitrification process within the BioDeNOx concept.     

Noise,not stimulus entropy,determines neural information rate

In the quest for deciphering the neural code, theoretical advances were made which allow for the determination of the information rate inherent in the spike trains of nerve cells. However, up to now, the dependence of the information rate on stimulus parameters has not been studied in any neuron in a systematic way. Here, I investigate the information carried by the spike trains of H1, a motion-sensitive visual interneuron of the blowfly (Calliphora vicina) using a moving grating as a stimulus. Stimulus parameters fall in two classes: those that have only a minor effect on the information rate like increasing the frequency bandwidth or the maximum amplitude of the stimulus velocity, and those which dramatically affect the neural information rate, like varying the spatial size or the contrast of the visual pattern being moved. It appears that, for a broad range of complex stimuli, the neuron covers the stimulus with its whole response repertoire regardless of the stimulus entropy, with the information rate being limited by the noise of the stimulus and the neural hardware.