Circadian Pattern of Wheel-Running Activity of a South American Subterranean Rodent (Ctenomys cf knightii)

Circadian rhythms are regarded as essentially ubiquitous features of animal behavior and are thought to confer important adaptive advantages. However, although circadian systems of rodents have been among the most extensively studied, most comparative biology is restricted to a few related species. In this study, the circadian organization of locomotor activity was studied in the subterranean, solitary north Argentinean rodent, Ctenomys knightii. The genus, Ctenomys, commonly known as Tuco-tucos, comprises more than 50 known species over a range that extends from 12S latitude into Patagonia, and includes at least one social species. The genus, therefore, is ideal for comparative and ecological studies of circadian rhythms. Ctenomys knightii is the first of these to be studied for its circadian behavior. All animals were wild caught but adapted quickly to laboratory conditions, with clear and precise activity-rest rhythms in a light-dark (LD) cycle and strongly nocturnal wheel running behavior. In constant dark (DD), the rhythm expression persisted with free-running periods always longer than 24h. Upon reinstatement of the LD cycle, rhythms resynchronized rapidly with large phase advances in 7/8 animals. In constant light (LL), six animals had free-running periods shorter than in DD, and 4/8 showed evidence of splitting. We conclude that under laboratory conditions, in wheel-running cages, this species shows a clear nocturnal rhythmic organization controlled by an endogenous circadian oscillator that is entrained to 24h LD cycles, predominantly by light-induced advances, and shows the same interindividual variable responses to constant light as reported in other non-subterranean species. These data are the first step toward understanding the chronobiology of the largest genus of subterranean rodents.

Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondonia, Brazil: sources and source processes, time series, diel variations and size distributions

Measurements of polar organic marker compounds were performed on aerosols that were collected at a pasture site in the Amazon basin (Rondonia, Brazil) using a high-volume dichotomous sampler (HVDS) and a Micro-Orifice Uniform Deposit Impactor (MOUDI) within the framework of the 2002 LBA-SMOCC (Large-Scale Biosphere Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate) campaign. The campaign spanned the late dry season (biomass burning), a transition period, and the onset of the wet season (clean conditions). In the present study a more detailed discussion is presented compared to previous reports on the behavior of selected polar marker compounds, including levoglucosan, malic acid, isoprene secondary organic aerosol (SOA) tracers and tracers for fungal spores. The tracer data are discussed taking into account new insights that recently became available into their stability and/or aerosol formation processes. During all three periods, levoglucosan was the most dominant identified organic species in the PM(2.5) size fraction of the HVDS samples. In the dry period levoglucosan reached concentrations of up to 7.5 mu g m(-3) and exhibited diel variations with a nighttime prevalence. It was closely associated with the PM mass in the size-segregated samples and was mainly present in the fine mode, except during the wet period where it peaked in the coarse mode. Isoprene SOA tracers showed an average concentration of 250 ng m(-3) during the dry period versus 157 ng m(-3) during the transition period and 52 ng m(-3) during the wet period. Malic acid and the 2-methyltetrols exhibited a different size distribution pattern, which is consistent with different aerosol formation processes (i.e., gas-to-particle partitioning in the case of malic acid and heterogeneous formation from gas-phase precursors in the case of the 2-methyltetrols). The 2-methyltetrols were mainly associated with the fine mode during all periods, while malic acid was prevalent in the fine mode only during the dry and transition periods, and dominant in the coarse mode during the wet period. The sum of the fungal spore tracers arabitol, mannitol, and erythritol in the PM(2.5) fraction of the HVDS samples during the dry, transition, and wet periods was, on average, 54 ng m(-3), 34 ng m(-3), and 27 ng m(-3), respectively, and revealed minor day/night variation. The mass size distributions of arabitol and mannitol during all periods showed similar patterns and an association with the coarse mode, consistent with their primary origin. The results show that even under the heavy smoke conditions of the dry period a natural background with contributions from bioaerosols and isoprene SOA can be revealed. The enhancement in isoprene SOA in the dry season is mainly attributed to an increased acidity of the aerosols, increased NO(x) concentrations and a decreased wet deposition.

Surface Plasmon-Induced Band Gap in the Photocurrent Response of Organic Solar Cells

A 260 nm layer of organic bulk heterojunction blend of the polymer poly(3-hexylthiophene) (P3HT) and the fullerene [6,6]-phenyl C(61)-butyric (PCBM) was spin-coated in between aluminum and gold electrodes, respectively, on top of a laser inscribed azo polymer surface-relief diffraction grating. Angle-dependent surface plasmons (SPs) with a large band gap were observed in the normalized photocurrent by the P3HT-PCBM layer as a function of wavelength. The SP-induced photocurrents were also investigated as a function of the grating depth and spacing.

An overview of the Amazonian Aerosol Characterization Experiment 2008 (AMAZE-08)

The Amazon Basin provides an excellent environment for studying the sources, transformations, and properties of natural aerosol particles and the resulting links between biological processes and climate. With this framework in mind, the Amazonian Aerosol Characterization Experiment (AMAZE-08), carried out from 7 February to 14 March 2008 during the wet season in the central Amazon Basin, sought to understand the formation, transformations, and cloud-forming properties of fine-and coarse-mode biogenic aerosol particles, especially as related to their effects on cloud activation and regional climate. Special foci included (1) the production mechanisms of secondary organic components at a pristine continental site, including the factors regulating their temporal variability, and (2) predicting and understanding the cloud-forming properties of biogenic particles at such a site. In this overview paper, the field site and the instrumentation employed during the campaign are introduced. Observations and findings are reported, including the large-scale context for the campaign, especially as provided by satellite observations. New findings presented include: (i) a particle number-diameter distribution from 10 nm to 10 mu m that is representative of the pristine tropical rain forest and recommended for model use; (ii) the absence of substantial quantities of primary biological particles in the submicron mode as evidenced by mass spectral characterization; (iii) the large-scale production of secondary organic material; (iv) insights into the chemical and physical properties of the particles as revealed by thermodenuder-induced changes in the particle number-diameter distributions and mass spectra; and (v) comparisons of ground-based predictions and satellite-based observations of hydrometeor phase in clouds. A main finding of AMAZE-08 is the dominance of secondary organic material as particle components. The results presented here provide mechanistic insight and quantitative parameters that can serve to increase the accuracy of models of the formation, transformations, and cloud-forming properties of biogenic natural aerosol particles, especially as related to their effects on cloud activation and regional climate.

Carbon Stocks and Isotopic Composition of the Organic Matter in Soils Covered by Native Vegetation and Pasture in Sorocaba, SP, Brazil

Land cover change constitutes one of main way of alteration of soil organic matter in both quantitative and qualitative terms. The goal of this study was to compare the carbon stock and the isotopic signature of the organic matter in the soil of areas with different land use,covered with forest and grass (pasture). The study area is located at Sorocaba, SP, Brazil. Using un-deformed soil samples, we measured the carbon content and bulk density. The isotopic signature of soil carbon was determined through the analysis of isotopic ratio (12)C/(13)C. The pasture soil stocks 48% less carbon than the soil covered by natural forest. The isotopic signature indicated that 42.2% of organic matter of the soil covered by pasture is originated from grasses. This characterizes a highly degradation of organic matter in the environment, both quantitatively and qualitatively. Hence, some guidelines of recuperation are described in order to restore the soil organic matter, structure and porosity.

Effect of terbium(III) on the binding of aromatic guests with sodium taurocholate aggregates

The effect of binding Tb(3+) to sodium taurocholate aggregates containing polyaromatic hydrocarbon guests was examined using pyrene and 1-ethylnaphthalene as guests that bind to the primary aggregate, and 1-naphthyl-1-ethanol as a secondary aggregate guest. Time-resolved fluorescence quenching studies were used to study the binding site properties, while laser flash photolysis quenching studies provided information on the dynamics of the guest-aggregate system. Both the primary and secondary aggregate binding sites became more compact in the presence of bound Tb(3+), while only the primary aggregate became more accessible to anionic molecules. The binding dynamics for the guest-primary aggregate system became faster when Tb(3+) was bound to the aggregate. In contrast, for the guest-secondary aggregate the presence of Tb(3+) resulted in a small decrease in the dissociation rate constant. The influence of bound Tb(3+) on the primary and secondary bile salt aggregates is significantly different, which affects how these aggregates can be used as supramolecular host systems to modify guest reactivity.

Effects of 7-Epiclusianone on Streptococcus mutans and Caries Development in Rats

The aim of this study was to evaluate the effects of 7-epiclusianone (7-epi) on specific virulence attributes of Streptococcus mutans in vitro and on development of dental caries in vivo. 7-Epi was obtained and purified from fruits of Rheedia brasiliensis. We investigated its influence on surface-adsorbed glucosyltransferase (Gtf) B activity, acid production, and viability of S. mutans in biofilms, as well as on caries development using a rodent model. 7-Epi (100 mu g/mL) significantly reduced the activity of surface-adsorbed GtfB (up to 48.0 +/- 1.8 of inhibition at 100 mu g/mL) and glyco-lytic pH-drop by S. mutans in biofilms (125 and 250 mu g/mL) (vs. vehicle control, p < 0.05). In contrast, the test compound did not significantly affect the bacterial viability when compared to vehicle control (15% ethanol, p > 0.05). Wistar rats treated topically with 7-epi (twice daily, 60-s exposure) showed significantly smaller number of and less severe smooth-and sulcal-surface carious lesions (p < 0.05), without reducing the S. mutans viable population from the animals` dental biofilms. In conclusion, the natural compound 7-epiclusianone may be a potentially novel pharmacological agent to prevent and control dental caries disease.

Nanoscale Oxidative Patterning of Metallic Surfaces to Modulate Cell Activity and Fate

In the field of regenerative medicine, nanoscale physical cuing is clearly becoming a compelling determinant of cell behavior. Developing effective methods for making nanostructured surfaces with well-defined physicochemical properties is thus mandatory for the rational design of functional biomaterials. Here, we demonstrate the versatility of simple chemical oxidative patterning to create unique nanotopographical surfaces that influence the behavior of various cell types, modulate the expression of key determinants of cell activity, and offer the potential of harnessing the power of stem cells. These findings promise to lead to a new generation of improved metal implants with intelligent surfaces that can control biological response at the site of healing.

Bunodosine 391: An Analgesic Acylamino Acid from the Venom of the Sea Anemone Bunodosoma cangicum

A new acylamino acid, bunodosine 391 (BDS 391), was isolated from the venom of the sea anemone Bunodosoma cangicum. The structure was elucidated by spectroscopic analyses (2D NMR, ESIMS/MS) and verified by its synthesis. Intraplantar injection of BDS 391 into the hind paw of a rat induced a potent analgesic effect. This effect was not altered by naloxone (an opioid receptor antagonist), but was completely reversed by methysergide (a serotonin receptor antagonist), indicating that the effect is mediated by activation of serotonin receptors:

Development and Validation of a Mice liar Electrokinetic Chromatography Method for Quantitative Determination of Butenolides in Piper malacophyllum (C. Presl) C. DC.

Introduction - A large number of natural and synthetic compounds having butenolides as a core unit have been described and many of them display a wide range of biological activities. Butenolides from P. malacophyllum have presented potential antifungal activities but no specific, fast, and precise method has been developed for their determination. Objective - To develop a methodology based on micellar electrokinetic chromatography to determine butenolides in Piper species. Methodology - The extracts were analysed in an uncoated fused-silica capillaries and for the micellar system 20 mmol/L SDS, 20% (v/v) acetonitrile (ACN) and 10 mmol/L STB aqueous buffer at pH 9.2 were used. The method was validated for precision, linearity, limit of detection (LOD) and limit of quantitation (LOQ) and the standard deviations were determined from the standard errors estimated by the regression line. Results - A micellar electrokinetic chromatography (MEKC) method for determination of butenolides in extracts gave full resolution for 1 and 2. The analytical curve in the range 10.0-50.0 mu g/mL (r(2) = 0.999) provided LOD and LOQ for 1 and 2 of 2.1/6.3 and 1.1/3.5 mu g/mL, respectively. The RSD for migration times were 0.12 and 1.0% for peak area ratios with 100.0 +/- 1.4% of recovery. Conclusions - A novel high-performance MEKC method developed for the analysis of butenolides 1 and 2 in leaf extracts of P. malacophyllum allowed their quantitative determined within an analysis time shorter than 5 min and the results indicated CE to be a feasible analytical technique for the quantitative determination of butenolides in Piper extracts. Copyright (C) 2010 John Wiley & Sons, Ltd.

Absolute Configuration and Selective Trypanocidal Activity of Gaudichaudianic Acid Enantiomers

Gaudichaudianic acid, a prenylated chromene isolated from Piper gaudichaudianum, has been described as a potent trypanocidal compound against the Y-strain of Trypanosoma cruzi. We herein describe its isolation as a racemic mixture followed by enantiomeric resolution using chiral HPLC and determination of the absolute configuration of the enantiomers as (+)-S and (-)-R by means of a combination of electronic and vibrational circular dichroism using density functional theory calculations. Investigation of the EtOAc extract of the roots, stems, and leaves from both adult specimens and seedlings of P. gaudichaudianum revealed that gaudichaudianic acid is biosynthesized as a racemic mixture from the seedling stage onward. Moreover, gaudichaudianic acid was found exclusively in the roots of seedlings, while it is present in all organs of the adult plant. Trypanocidal assays indicated that the (+)-enantiomer was more active than its antipode. Interestingly, mixtures of enantiomers stowed a synergistic effect, with the racemic mixture being the most active.

Effects of Molybdenum, Nickel, and Nitrogen Sources on the Mineral Nutrition and Growth of Rice Plants

Upland rice plants, cultivar `IAC 202,` were grown in nutrient solution until full tillering. Treatments consisted of ammonium nitrate (AN) or urea (UR) as nitrogen (N) source plus molybdenum (Mo) and/or nickel (Ni): AN + Mo + Ni, AN + Mo - Ni, AN - Mo + Ni, UR + Mo + Ni, UR + Mo - Ni, and UR - Mo + Ni. The experiment was carried out to better understand the effect of these treatments on dry-matter yield, chlorophyll, net photosynthesis rate, nitrate (NO3 --N), total N, in vitro activities of urease and nitrate reductase (NR), and Mo and Ni concentrations. In UR-grown plants, Mo and Ni addition increased yield of dry matter. Regardless of the N source, chlorophyll concentration and net photosynthesis rate were reduced when Mo or Ni were omitted, although not always significantly. The omission of either Mo or Ni led to a decrease in urease activity, independent of N source. Nitrate reductase activity increased in nutrient solutions without Mo, although NO3 --N increased. There was not a consistent variation in total N concentration. Molybdenum and Ni concentration in roots and shoots were influenced by their supply in the nutrient solution. Molybdenum concentration was not influenced by N sources, whereas Ni content in both root and shoots was greater in ammonium nitrate-grown plants. In conclusion, it can be hypothesized that there is a relationship between Mo and Ni acting on photosynthesis, although is an indirect one. This is the first evidence for a beneficial effect of Mo and Ni interaction on plant growth.

Three filter beds for arsenite and chromate removal

Arsenic (As) and chromium (Cr) are two of the most toxic pollutants introduced into natural waters from a variety of sources, and they cause various adverse effects on living bodies when their concentrations exceed permissible limits. Laboratory experiments have been conducted to investigate the sorption of As and Cr on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of As and Cr species for iron/iron carbide (Fe/Fe3C) sites is the key factor in controlling the removal of the elements. The method is based on the use of powder carbon steel, powdered block carbon, and ball ceramic in the ion-sorption columns as a cleaning process. The presence of carbon steel in a system that contains As3+ and Cr6+ might have a potential effect.

Antimicrobial activity of Rheedia brasiliensis and 7-epiclusianone against Streptococcus mutans

This in vitro study evaluated the antimicrobial activity of extracts obtained from Rheedia brasiliensis fruit (bacupari) and its bioactive compound against Streptococcus mutans. Hexane, ethyl-acetate and ethanolic extracts obtained (concentrations ranging from 6.25 to 800 mu g/ml) were tested against S. mutans UA159 through MIC/MBC assays. S. mutans 5-days-old biofilms were treated with the active extracts (100 x MIC) for 0, 1, 2, 3 and 4 h (time-kill) and plated for colony counting (CFU/ml). Active extracts were submitted to exploratory chemical analyses so as to isolate and identify the bioactive compound using spectroscopic methods. The bioactive compound (concentrations ranging from 0.625 to 80 mu g/ml) was then tested through MIC/MBC assays. Peel and seed hexane extracts showed antimicrobial activity against planktonic cells at low concentrations and were thus selected for the time kill test. These hexane extracts reduced S. mutans biofilm viability after 4 h, certifying of the bioactive compound presence. The bioactive compound identified was the polyprenylated benzophenone 7-epiclusianone, which showed a good antimicrobial activity at low concentrations (MIC: 1.25-2.5 mu g/ml; MBC: 10-20 mu g/ml). The results indicated that 7-epiclusianone may be used as a new agent to control S. mutans biofilms; however, more studies are needed to further elucidate the mechanisms of action and the anticariogenic potential of such compound found in R. brasiliensis. (C) 2008 Elsevier GmbH. All rights reserved.

Yield, Potassium Uptake, and Use Efficiency in Upland Rice Genotypes

Potassium (K) is an essential nutrient for higher plants. Information on K uptake and use efficiency of upland rice under Brazilian conditions is limited. A greenhouse experiment was conducted with the objective to evaluate influence of K on yield, K uptake, and use efficiency of six upland rice genotypes grown on Brazilian Oxisol. The K rate used was zero (natural soil level) and 200 mg K kg-1 of soil. Shoot dry weight and grain yield were significantly influenced by K level and genotype treatments. However, K x genotype interactions were not significant, indicating similar responses of genotypes at two K levels for shoot dry weight and grain yield. Genotypes produced grain yield in the order of BRS Primavera BRA 01596 BRSMG Curinga BRS 032033 BRS Bonanca BRA 02582. Potassium concentration in shoot was about sixfold greater compared to grain, across two K levels and six genotypes. However, K utilization efficiency ratio (KUER) (mg shoot or grain yield / mg K uptake in shoot or root) was about 6.5 times greater in grain compared to shoot, across two K level and six genotypes. Potassium uptake in shoot and grain and KUER were significantly and positively associated with grain yield. Soil calcium (Ca), K, base saturation, acidity saturation, Ca saturation, K saturation, Ca/K ratio, and magnesium (Mg)/K ratio were significantly influenced by K application rate.