Construction and analysis of a high-CO2-requiring mutant of the cyanobacterium Anabaena sp strain PCC7120

A mutant of Anabaena sp. strain PCC7120 requiring high CO2 was generated using Tn5 mutagenesis. This is the first data for a filamentous cyanobacterium. The mutant was capable of growing at 5% CO2, but incapable of growing at air levels of CO2. Southern hybridization analysis indicated that the Anabaena genome was inserted by the transposon at one site. The apparent photosynthetic affinity of the mutant to external dissolved inorganic carbon (DIC) was about 300 times lower that of the wild type (WT), and the medium alkalization rate as well as the carboxysomal carbonic anhydrase activity of the mutant was also lower than those of the WT. When the mutant was transferred from the culture medium bubbled with 5% CO2 to higher DIC (8.4% CO2) or 1% CO2, it showed similar responses to the WT. However, aberrant carboxysomes were found in the mutant cells through ultrastructural analysis, indicating it was most probably the wrong organization of the carboxysomes that eventually led to the inefficient operation of carboxysomal carbonic anhydrase and the subsequent defectiveness of the mutant in utilizing DIC.

Nitrogen and carbon dynamics in grassland soils and plants after application of digestate

A better understanding of effects after digestate application on plant community, soil microbial community as well as nutrient and carbon dynamics is crucial for a sustainable grassland management and the prevention of species and functional diversity loss. The specific research objectives of the thesis were: (i) to investigate effects after digestate application on grass species and soil microbial community, especially focussing on nitrogen dynamic in the plant-soil system and to examine the suitability of the digestate from the “integrated generation of solid fuel and biogas from biomass” (IFBB) system as fertilizer (Chapter 3). (ii) to investigate the relationship between plant community and functionality of soil microbial community of extensively managed meadows, taking into account temporal variations during the vegetation period and abiotic soil conditions (Chapter 4). (iii) to investigate the suitability of IFBB-concept implementation as grassland conservation measure for meadows and possible associated effects of IFBB digestate application on plant and soil microbial community as well as soil microbial substrate utilization and catabolic evenness (Chapter 5). Taken together the results indicate that the digestate generated during the IFBB process stands out from digestates of conventional whole crop digestion on the basis of higher nitrogen use efficiency and that it is useful for increasing harvestable biomass and the nitrogen content of the biomass, especially of L. perenne, which is a common species of intensively used grasslands. Further, a medium application rate of IFBB digestate (50% of nitrogen removed with harvested biomass, corresponding to 30 50 kg N ha-1 a-1) may be a possibility for conservation management of different meadows without changing the functional above- and belowground characteristic of the grasslands, thereby offering an ecologically worthwhile alternative to mulching. Overall, the soil microbial biomass and catabolic performance under planted soil was marginally affected by digestate application but rather by soil properties and partly by grassland species and legume occurrence. The investigated extensively managed meadows revealed a high soil catabolic evenness, which was resilient to medium IFBB application rate after a three-year period of application.

Optimized synthesis of the melatonin metabolite N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Use of sugar cane bagasse as solid phase extractor for cadmium determination by FAAS

The present paper describes the use of sugar cane bagasse as solid phase extractor for cadmium determination after complexation of the analyte with ammonium diethyldithiophosphate (ADDP) and sorption of the Cd-DDP complexes on the solid support. The concomitants were separated using a flow injection analysis (FIA) system coupled to flame atomic absorption spectrometry (FAAS) for determination. The main parameters such as ADDP concentration, acid medium, flow rate, reaction coil length, and reaction time were investigated.The results obtained with HNO3 showed good accuracy and precision. The enhancement factor was 20.5 times for a 120-second preconcentration time, and the analytical frequency was 25 determinations per hour. The calibration curve was linear over the concentration range of 1-40 mu g L-1 Cd with a LOD of 0.697 mu g L-1 Cd and a relative standard deviation of 0.96% after 12 successive measurements of 30 mu g L-1 Cd.The proposed method was evaluated for the FIA-FAAS analysis of certified reference materials (tomato leaves, spinach leaves, and bovine liver) and Cd-spiked foods (shrimp, sardine, tuna, chicken liver and bovine liver). Good recoveries (80.0-97.1%) for the Cd-spiked samples and certified reference materials were obtained. The results of bagasse-packed minicolumns were compared with Si-C,8 packed minicolumns. The F-test was applied between Si-C-18/Bagasse minicolumns, Si-C-18/certified values, and bagasse/certified values. It was found that the results were in agreement with the certified values at a 95% confidence level.

Modeling and simulation of cephalosporin C production in a fed-batch tower-type bioreactor

Immobilized cell utilization in tower-type bioreactor is one of the main alternatives being studied to improve the industrial bioprocess. Other alternatives for the production of beta -lactam antibiotics, such as a cephalosporin C fed-batch p recess in an aerated stirred-tank bioreactor with free cells of Cepha-losporium acremonium or a tower-type bioreactor with immobilized cells of this fungus, have proven to be more efficient than the batch profess. In the fed-batch process, it is possible to minimize the catabolite repression exerted by the rapidly utilization of carbon sources (such as glucose) in the synthesis of antibiotics by utilizing a suitable flow rate of supplementary medium. In this study, several runs for cephalosporin C production, each lasting 200 h, were conducted in a fed-batch tower-type bioreactor using different hydrolyzed sucrose concentrations, For this study's model, modifications were introduced to take into account the influence of supplementary medium flow rate. The balance equations considered the effect of oxygen limitation inside the bioparticles. In the Monod-type rate equations, eel concentrations, substrate concentrations, and dissolved oxygen were included as reactants affecting the bioreaction rate. The set of differential equations was solved by the numerical method, and the values of the parameters were estimated by the classic nonlinear regression method following Marquardt's procedure with a 95% confidence interval. The simulation results showed that the proposed model fit well with the experimental data,and based on the experimental data and the mathematical model an optimal mass flow rate to maximize the bioprocess productivity could be proposed.

Accumulation of glucose and protein hydrolysate by natural populations of microorganisms in the Black Sea and Atlantic Ocean

Accumulation rate of dissolved organic matter (DOM) by natural populations varies over a wide range. In the surface layer of the Black Sea accumulation rate of glucose is 0.6-4.82 mg C/m**3 per day, and in the Atlantic Ocean 1.15-12.38 mg C/m**3 per day. This rate is 2-17 times higher when hydrolysate is added to the medium. Accumulation rate of glucose and hydrolysate in the aphotic layer of the Black Sea and the Atlantic Ocean is 1.5-6 times lower than at the surface. The organotrophic coefficient also varied within wide range. Relative amount of DOM used by microorganisms for growth in total production is much less (0.6-39.9%) in areas of intensive photosynthesis than in waters poor in DOM (83.7-99.2%).

Directional Guidance of Nicotiana alata Pollen Tubes in Vitro and on the Stigma1

Pollen tubes navigate the route from stigma to ovule with great accuracy, but the cues that guide them along this route are not known. We reproduced the environment on the stigma of Nicotiana alata by immersing pollen in stigma exudate or oil close to an interface with an aqueous medium. The growth of pollen in this culture system mimicked growth on stigmas: pollen grains hydrated and germinated, and pollen tubes grew toward the aqueous medium. The rate-limiting step in pollen germination was the movement of water through the surrounding exudate or oil. By elimination of other potential guidance cues, we conclude that the directional supply of water probably determined the axis of polarity of pollen tubes and resulted in growth toward the interface. We propose that a gradient of water in exudate is a guidance cue for pollen tubes on the stigma and that the composition of the exudate must be such that it is permeable enough for pollen hydration to occur but not so permeable that the supply of water becomes nondirectional. Pollen tube penetration of the stigma may be the most frequently occurring hydrotropic response of higher plants.

A new rapidly absorbed paracetamol tablet containing sodium bicarbonate. II. Dissolution studies and in vitro/in vivo correlation

The objective of this study was to compare the in vitro dissolution profile of a new rapidly absorbed paracetamol tablet containing sodium bicarbonate (PS) with that of a conventional paracetamol tablet (P), and to relate these by deconvolution and mapping to in vivo release. The dissolution methods used include the standard procedure described in the USP monograph for paracetamol tablets, employing buffer at pH5.8 or 0.05 M HCl at stirrer speeds between 10 and 50 rpm. The mapping process was developed and implemented in Microsoft Excel® worksheets that iteratively calculated the optimal values of scale and shape factors which linked in vivo time to in vitro time. The in vitro-in vivo correlation (IVIVC) was carried out simultaneously for both formulations to produce common mapping factors. The USP method, using buffer at pH5.8, demonstrated no difference between the two products. However, using an acidic medium the rate of dissolution of P but not of PS decreased with decreasing stirrer speed. A significant correlation (r=0.773; p<.00001) was established between in vivo release and in vitro dissolution using the profiles obtained with 0.05 M HCl and a stirrer speed of 30 rpm. The scale factor for optimal simultaneous IVIVC in the fasting state was 2.54 and the shape factor was 0.16; corresponding values for mapping in the fed state were 3.37 and 0.13 (implying a larger in vitro-in vivo time difference but reduced shape difference in the fed state). The current IVIVC explains, in part, the observed in vivo variability of the two products. The approach to mapping may also be extended to different batches of these products, to predict the impact of any changes of in vitro dissolution on in vivo release and plasma drug concentration-time profiles.

Factors affecting the growth of Cladophora in relation to river pollution

Nuisance growths of Cladophora have been associated with eutrophication. A review of the literature, however, reveals a scarcity of relevant experimental growth studies. Sampling experimental streams reveals that the addition of sewage effluent to good quality water alters the flora from that dominated by Potamogetan crispus to one dominated by CLadophora. Spatial and temporal differences in biomass of taxa present are discussed in the context of accompanying physicochemical data. In laboratory batch culture, growth of unialgal C. glomerata was accompanied by elevation of medium pH - considered largely responsible for the poor growth in such culture. However, appropriate experimental conditions and indices of growth were selected and the effects of various herbicides assessed. Diquat and terbutryne were shown to possess algicidal activity towards Cladophora. A closed continuous culture apparatus was developed: growth proceeded through lag, logarithmic and linear phases. Inoculum size and medium flow rate had significant effects on growth, and were standardized. In continuous culture, specific growth rate increased linearly with increased duration of light per day, up to 24 hours, and increased light intensity, up to 6000 lux - the highest intensity tested. Comparison of field and laboratory results suggests that ammonia toxicity is attributable to the undissociated form. In the laboratory, 185 µg/1 undissociated ammoniacal nitrogen reduced specific growth rate to 50% of that at 10 µg/1 undissociated ammcniacal nitrogen. 0.077-1.057 mg/1 NO2-N had no significant effect on growth. 7.2-15.2 mg/1 NO3-N had no significant effect on specific growth rate. Neither was any nitrate/phosphate interaction significant. At 4.9 mg/1 PO4-1, specific growth rate was only 48% of that at 1.9 g/1 P04-P. The critical medium PO4-P concentration was <0.1 mg/i. Specific growth rate was reduced to 50% of that in natural water by 0.036 mgCu/l, 0.070 mgzn/1 and 1.03 mgPb/l. Metal uptake was evaluated.

Exploratory Study of the Download Speed of Leading University Hospitality and Tourism Department Websites Worldwide

Increased broadband penetration (BP) rates around the world have encouraged web designers to include more web content and additional functions on their web sites, thereby enhancing the richness and playfulness of the information. However, it is often very difficult for web surfers who are still using narrowband connections to access such web sites. Many university web sites target international audiences; therefore their download performance should be considered, as it may directly influence the user experience. This exploratory study examined 331 university hospitality and tourism department web sites in 37 countries. The empirical results showed that entry web pages of universities in Asia, with a medium BP rate (mid-BP), have the slowest download speeds, and those in Australia and New Zealand perform the best. The adoption rate of the Cascade Style Sheet (CSS) in Asia is relatively lower than that of other regions.

High rate filtration using buoyant medium : experiments and mathematical models

In this study, the high rate filtration system using buoyant medium of polypropylene or polystyrene was introduced with the study on its performance evaluation via: (i) specific surface coverage, (ii) ultimate specific deposit, (iii) blocking effect and (iv) particle detachment. The filter system was arranged in the downflow mode with an in-line flocculation. Experimental results obtained were analyzed using filtration models. This study showed that: (i) the specific surface coverage increased with the increase in the velocity; (ii) the ultimate specific deposit changed slightly at different filtration velocities and different flocculants; (iii) the blocking effect was significant in the transient stage removal of flocs; and (iv) the detachment model parameter was found to decrease with the increase in the adhesive force, Fad that acts on the flocs (above-micron size).

Sperm motility of Prochilodus lineatus in relation to dilution rate and temperature of the activating medium

The objective of this study was to assess the effects of an activating solution on the sperm motility duration (SMD) of 'curimbatá', Prochilodus lineatus through of the definition of qualitative and quantitative parameters of the semen pool used in the experiment; evaluation of the effects of different ratios of semen dilution corresponding to 1-:-1, 1-:-2, 1-:-20, 1-:-200, 1-:-2000, 1-:-20-000 and 1-:-100-000 semen:dilute solution on the SMD and, assessment of the effects of different temperatures of the activating solution (5, 10, 15, 20, 25, 30, 35, 40, 45 and 50°C) on the SMD. The results of SMD were directly proportional to the dilution (P<0.05), starting from the dilution of 1-:-2 (semen:water), with 23.04-s. Were used three replicates of the semen pool for each test. Two-year-old brookstock were maintained in ponds culture conditions. In November-December 2006, twelve mature males broodfish were selected (mean weight and length of 405.8±134.2-g and 25.6±3.1-cm, respectively). The males released that semen under slight pressure of the urogenital papilla were selected for the experiment. The SMD increased proportionally to the increase in dilution, until it reached a maximum of 28.83-s for the ratio 1-:-100-000 semen: dilute solution. The results of SMD in relation to the temperature of the activating solution exhibited a quadratic behavior (P<0.05) with a maximum theoretical performance in terms of sperm motility duration of 21.36-s at a temperature of 17.3°C. Thus, for the species considered, the increase in the dilution ratio proved favorable for the rise in motility duration until the maximum value studied of 1-:-100-000 semen:dilute solution. As for the temperature of the activating solution, the best results of SMD were obtained at the temperature of 17.3°C. At higher temperatures used in the experiment (25, 30, 35, 40, 45 and 50°C), a decrease in motility duration. © 2010 Blackwell Verlag, Berlin.

Investigating the cosmic-ray ionization rate in the galactic interstellar medium through observations of H3+

Observations of H3+ in the Galactic diffuse interstellar medium (ISM) have led to various surprising results, including the conclusion that the cosmic-ray ionization rate (zeta_2) is about 1 order of magnitude larger than previously thought. The present survey expands the sample of diffuse cloud sight lines with H3+ observations to 50, with detections in 21 of those. Ionization rates inferred from these detections are in the range (1.7+-1.0)x10^-16 s^-1 < zeta_2 < (10.6+-6.8)x10^-16 s^-1 with a mean value of zeta_2=(3.3+-0.4)x10^-16 s^-1. Upper limits (3sigma) derived from non-detections of H3+ are as low as zeta_2 < 0.4x10^-16 s^-1. These low upper-limits, in combination with the wide range of inferred cosmic-ray ionization rates, indicate variations in zeta_2 between different diffuse cloud sight lines. Calculations of the cosmic-ray ionization rate from theoretical cosmic-ray spectra require a large flux of low-energy (MeV) particles to reproduce values inferred from observations. Given the relatively short range of low-energy cosmic rays --- those most efficient at ionization --- the proximity of a cloud to a site of particle acceleration may set its ionization rate. Variations in zeta_2 are thus likely due to variations in the cosmic-ray spectrum at low energies resulting from the effects of particle propagation. To test this theory, H3+ was observed in sight lines passing through diffuse molecular clouds known to be interacting with the supernova remnant IC 443, a probable site of particle acceleration. Where H3+ is detected, ionization rates of zeta_2=(20+-10)x10^-16 s^-1 are inferred, higher than for any other diffuse cloud. These results support both the concept that supernova remnants act as particle accelerators, and the hypothesis that propagation effects are responsible for causing spatial variations in the cosmic-ray spectrum and ionization rate. Future observations of H3+ near other supernova remnants and in sight lines where complementary ionization tracers (OH+, H2O+, H3O+) have been observed will further our understanding of the subject.

Effects of different practice task constraints on fluctuations of player heart rate in small-sided football games

This paper analyzes effects of different practice task constraints on heart rate (HR) variability during 4v4 smallsided football games. Participants were sixteen football players divided into two age groups (U13, Mean age: 12.4±0.5 yrs; U15: 14.6±0.5). The task consisted of a 4v4 sub-phase without goalkeepers, on a 25x15 m field, of 15 minutes duration with an active recovery period of 6 minutes between each condition. We recorded players’ heart rates using heart rate monitors (Polar Team System, Polar Electro, Kempele, Finland) as scoring mode was manipulated (line goal: scoring by dribbling past an extended line; double goal: scoring in either of two lateral goals; and central goal: scoring only in one goal). Subsequently, %HR reserve was calculated with the Karvonen formula. We performed a time-series analysis of HR for each individual in each condition. Mean data for intra-participant variability showed that autocorrelation function was associated with more short-range dependence processes in the “line goal” condition, compared to other conditions, demonstrating that the “line goal” constraint induced more randomness in HR response. Relative to inter-individual variability, line goal constraints demonstrated lower %CV and %RMSD (U13: 9% and 19%; U15: 10% and 19%) compared with double goal (U13: 12% and 21%; U15: 12% and 21%) and central goal (U13: 14% and 24%; U15: 13% and 24%) task constraints, respectively. Results suggested that line goal constraints imposed more randomness on cardiovascular stimulation of each individual and lower inter-individual variability than double goal and central goal constraints.