Interaction between the mineral content and the occurrence number of aquatic fungi in leaves submerged in a stream in the Atlantic rainforest, São Paulo, Brazil

Leaves of Ficus microcarpa L. f., Quercus robur L., and Alchornea triplinervia (Spreng.) Muell. Arg., submerged in a stream of the Atlantic rainforest in the "Reserva Biológica do Alto da Serra de Paranapiacaba", State of São Paulo, Brazil, were collected monthly, from April to November 1990, in order to determine the number of fungal occurrences (zoosporic fungi and aquatic Hyphomycetes), and the content of total N (%), total P (%), K+ (%), Ca+2 (%), Mg+2 (%), S+3 (%), Fe+3 (ppm), Cu+3 (ppm), Mn+2 (ppm), Zn+2 (ppm), Bo (ppm), Na+2 (ppm) and Al+3 (ppm). According to the tests of Kruskal-Wallis, Mann-Whitney and Wilcoxon, the means of the mineral content of the three types of leaves were significantly different, except for Mg+2 (%), Mn+2 (ppm), Zn+2 (ppm) and Na+2 (ppm). On comparing the mineral content with the number of fungal occurrence, an independence test showed a positive correlation between the presence of zoosporic fungi on the leaves of A. triplinervia and the total nitrogen, phosphorus and S+3 content, whereas the aquatic Hyphomycetes depended on the amount of Ca+2 available. Regarding leaves of F. microcarpa, the occurrence of zoosporic fungi was linked to the S+3 level, and the presence of aquatic Hyphomycetes, to the content of K+, Ca+2, S+3 and Bo. On Q. robur leaves, zoosporic fungi showed a positive correlation with the Ca+2 content, but a negative one with Fe+3 and Al+3 levels, while the occurrence of aquatic Hyphomycetes was influenced by the content of Ca+2, Mg+2, Fe+3, Al+3, Mn+2, Zn+2 and Na+2. The correlation between the occurrence number of aquatic Hyphomycetes and a high mineral content indicates that their nutritional requirements may be more complex than those of zoosporic fungi. Further studies are still required to understand the implications of this tendency on the diversity of aquatic native mycota.

Acute experimental Trypanosoma cruzi infection: establishing a murine model that utilises non-invasive measurements of disease parameters

Trypanosoma cruzi infection has a large public health impact in Latin American countries. Although the transmission rates via blood transfusions and insect vectors have declined sharply in the past 20 years due to policies of the Southern Cone countries, a large number of people are still at risk for infection. Currently, no accepted experimental model or descriptions of the clinical signs that occur during the course of acute murine infection are available. The aim of this work was to use non-invasive methods to evaluate the clinical signs of Balb/c mice infected with the Y strain of T. cruzi. The infected mice displayed evident clinical changes beginning in the third week of infection. The mice were evaluated based on physical characteristics, spontaneous activity, exploratory behaviour and physiological alterations. We hope that the results presented in this report provide parameters that complement the effective monitoring of trypanocidal treatment and other interventions used to treat experimental Chagas disease.

Characterization of capacitive sensors for measurements of the moisture in irrigated soils

The irrigation is a technique developed to supply the hydric needs of the plants. The use of the water should be optimized so that the culture just has enough for its growth, avoiding waste. The objective of this work was to characterize the behavior of capacitive sensors of humidity to monitor the moisture in the soils. In first instance, it was appraised sensors with dielectric built of synthetic pomes stone (Rd = 0,4 and Rd = 0,8) and of soil samples (Rd = 0,8 and Rd = 1,0), being the Rd parameter a geometric factor that relates the distance between the capacitor plates with radius of the plates. For the calibration, the sensors were installed in PVC recipient of cylindrical shape, filled with soil. The set (sensor and soil) was humidified by capillary effect and submitted by a natural drying very slowly. The parameter readings were taken daily, which allowed obtain the curves relating the humidity percentage, expressed in terms of dry weight, with the output voltage fort the sensor. The experiments were performed in sand soil and in dark red latossolo. The obtained results allowed to infer that the behavior of the sensor has a specific feature for each type of soil, being, therefore, necessary to develop a own calibration curve for the sensor, when used in soil with specific characteristic.

Synecological comparisons sustained by ecophysiological fingerprinting of intrinsic photosynthetic capacity of plants as assessed by measurements of light response curves

In some literature variations in photosynthetic rates are considered to be of little relevance for individual fitness. This depends among other things on how one defines fitness, i.e. if one takes strictly Darwinian fitness as seed production or if one needs to evaluate particular traits and consider plant establishment. It also matters if one takes the Darwinian "organism individual" as the central entity in evolution ("individual fitness") or the "species individual" in a modified "Structure of Evolutionary Theory" sensu Stephen Jay Gould. A phenotypically expressed trait like photosynthetic rate, even if intra- and interspecific differences may be small, can matter in habitat performance and niche acquisition. Light dependence curves (LCs) of photosynthetic rates are now readily measured under field conditions using miniaturized equipment of pulse amplitude modulated fluorometers. In contrast to actual momentary measurements of quantum yield of photosynthesis under actually prevailing ambient conditions, LC measurements reflect the expressed intrinsic capacity of photosynthesis. In this review we explore the power of LC measurements yielding cardinal points such as maximum apparent electron transport rate of photosystem II (ETRmax) and saturating photosynthetically active radiation (PARsat) in making intra- and interspecific comparisons of plant performance and synecological fingerprinting in ecophysiological studies across species, sites, habitats and ecosystems.

Electrophysiological measurements of spectral sensitivities: a review

Spectral sensitivities of visual systems are specified as the reciprocals of the intensities of light (quantum fluxes) needed at each wavelength to elicit the same criterion amplitude of responses. This review primarily considers the methods that have been developed for electrophysiological determinations of criterion amplitudes of slow-wave responses from single retinal cells. Traditional flash methods can require tedious dark adaptations and may yield erroneous spectral sensitivity curves which are not seen in such modifications as ramp methods. Linear response methods involve interferometry, while constant response methods involve manual or automatic adjustments of continuous illumination to keep response amplitudes constant during spectral scans. In DC or AC computerized constant response methods, feedback to determine intensities at each wavelength is derived from the response amplitudes themselves. Although all but traditional flash methods have greater or lesser abilities to provide on-line determinations of spectral sensitivities, computerized constant response methods are the most satisfactory due to flexibility, speed and maintenance of a constant adaptation level

Validation of transit-time flowmetry for chronic measurements of regional blood flow in resting and exercising rats

The objective of the present study was to validate the transit-time technique for long-term measurements of iliac and renal blood flow in rats. Flow measured with ultrasonic probes was confirmed ex vivo using excised arteries perfused at varying flow rates. An implanted 1-mm probe reproduced with accuracy different patterns of flow relative to pressure in freely moving rats and accurately quantitated the resting iliac flow value (on average 10.43 ± 0.99 ml/min or 2.78 ± 0.3 ml min-1 100 g body weight-1). The measurements were stable over an experimental period of one week but were affected by probe size (resting flows were underestimated by 57% with a 2-mm probe when compared with a 1-mm probe) and by anesthesia (in the same rats, iliac flow was reduced by 50-60% when compared to the conscious state). Instantaneous changes of iliac and renal flow during exercise and recovery were accurately measured by the transit-time technique. Iliac flow increased instantaneously at the beginning of mild exercise (from 12.03 ± 1.06 to 25.55 ± 3.89 ml/min at 15 s) and showed a smaller increase when exercise intensity increased further, reaching a plateau of 38.43 ± 1.92 ml/min at the 4th min of moderate exercise intensity. In contrast, exercise-induced reduction of renal flow was smaller and slower, with 18% and 25% decreases at mild and moderate exercise intensities. Our data indicate that transit-time flowmetry is a reliable method for long-term and continuous measurements of regional blood flow at rest and can be used to quantitate the dynamic flow changes that characterize exercise and recovery

Comparison of bone quantity by ultrasound measurements of phalanges between white and black children living in Paraná, Brazil, with Europeans

The objective of this study was to determine bone quantity by ultrasound measurements of the proximal finger phalanges (AD-SoS = amplitude-dependent speed of sound) of healthy Brazilian schoolchildren living in Paraná, Brazil and to compare these values with European populations. The sample was composed of 1356 Brazilian schoolchildren of both genders (660 males, 696 females), aged 6 to 11 years, divided into white (840) and black (516) groups and compared to age- and gender-matched Europeans. AD-SoS of the schoolchildren increased significantly with age for both genders. Significantly higher AD-SoS values were observed for the white children (1916 ± 58) compared to their black counterparts (1898 ± 72) and for the female gender (1920 ± 61) compared to the male gender (1898 ± 66). Overall, the AD-SoS outcomes for females were similar to those of European studies. However, the AD-SoS of the Brazilian schoolchildren of both genders and skin colors was lower than that reported for children in Poland. AD-SoS outcomes for Brazilian schoolboys were similar to those obtained in Italian studies and were lower than those of the Spanish children. In conclusion, Brazilian schoolchildren of both genders and skin colors showed lower bone quantities than Polish children and Spanish males, and levels similar to Italian children and Spanish females.

A comparative study among methods used for wheat flour analysis and for measurements of gluten properties using the Wheat Gluten Quality Analyser (WGQA)

This study aimed at comparing both the results of wheat flour quality assessed by the new equipment Wheat Gluten Quality Analyser (WGQA) and those obtained by the extensigraph and farinograph. Fifty-nine wheat samples were evaluated for protein and gluten contents; the rheological properties of gluten and wheat flour were assessed using the WGQA and the extensigraph/farinograph methods, respectively, in addition to the baking test. Principal component analysis (PCA) and linear regression were used to evaluate the results. The parameters of energy and maximum resistance to extension determined by the extensigraph and WGQA showed an acceptable level for the linear correlation within the range from 0.6071 to 0.6511. The PCA results obtained using WGQA and the other rheological apparatus showed values similar to those expected for wheat flours in the baking test. Although all equipment used was effective in assessing the behavior of strong and weak flours, the results of medium strength wheat flour varied. WGQA has shown to use less amount of sample and to be faster and easier to use in relation to the other instruments used.