ALBERT

Notes: 1 The present study aimed to evaluate the role of κ-opioid receptors at two peripheral sites, the vas deferens and the proximal colon, in κ-opioid receptor knockout mice. We investigated the role of the κ-opioid receptor in the vas deferens twitch response and in the colonic ‘off-contraction’, a rebound contractile response which follows the inhibitory response to low frequencies stimulation (10, 20, 30 Hz) and which has been suggested to ‘locally’ reproduce the contractile component of the peristaltic reflex. 2 Transmural stimulation of the vas deferens at lower frequencies (10 Hz, 10 V, 1 ms pulse trains lasting 0.5 s) evoked a contractile response that was significantly higher in the preparations from knockout mice because of lack of κ-opioid receptors than in wild type mice. A selective κ-opioid receptor agonist, U-50,488H, induced a dose-dependent inhibition of the electrically stimulated contraction in vas deferens. The percentages of reduction of the twitch response were significantly lower in knockout mice than in wild type mice after treatment with U-50,488H. The reduction of twitch response caused by U-50,488H was not reversed by administration of nor-binaltorphimine (nor-BNI) (5 × 10−6 m), a selective κ-opioid receptor antagonist, in preparations from both knockout mice and wild type mice. U-50,488H has no effect on postsynaptic adrenergic receptors, as its administration did not affect the direct contractile response to noradrenaline. 3 Transmural stimulation (5 Hz, 20 V, 2 ms pulse trains lasting 30 s) induced inhibition of spontaneous activity of colonic strips during the period of stimulation, followed by an ‘off-contraction’ after the cessation of stimulation. The statistical evaluation of the ‘off-contraction’ responses between the two strains showed no significant difference. The off-contraction, measured in specimens from knockout mice, was inhibited concentration-dependently by U-50,488H (P 〈 0.01) and significantly less than from wild type mice. 4 The effect of U-50,488H was not reversed by administration of nor-BNI (5 × 10−6 m), either in preparations from knockout mice or from wild type mice. 5 Our data may suggest that κ-opioid receptors are involved in some peripheral responses to the nerve stimulation, as indicated by the effect of U-50,488H, a selective κ-opioid receptor agonist. However, the involvement of κ-opioid receptor was also present, although less apparent, in κ -opioid receptor knockout mice, suggesting either that this drug acts not only on κ-opioid receptors but also on other receptor sites, such as κ-like receptors. An alternative interpretation can be related to a sodium channel blocking action of U-50,488H, which could explain the inhibitory effects of twitch response still present but less evident in knockout strain and the lack of effect of the antagonist nor-BNI.

Notes: A new filtering technique for single-fold wide-angle reflection/refraction seismic data is presented. The technique is based on the wavelet decomposition of a set of adjacent traces followed by coherence analysis. The filtering procedure consists of three steps. In the first, a wavelet decomposition of traces into different detail levels is performed. In the second, the coherence attributes for each level are evaluated by calculating cross-correlation functions of detail portions contained in a space–time moving window. Finally, the filtered traces are obtained as a weighted reconstruction of the trace details. Each weight is obtained from the coherence-attributes distribution estimated in a proper interval. A sequence of tests is then conducted in order to select possible optimum or unsuitable wavelet bases. The efficiency of the filter proposed was assessed by calculating some properly designed parameters in order to compare it with other standard de-noising techniques. The proposed method produced a clear signal enhancement in high-density wide-angle seismic data, thus proving that it is a useful processing tool for a reliable correlation of seismic phases.

Notes: The mineralization of nitrogen from soil organic matter is important when one tries to optimize nitrogen fertilization and assess risks of N losses to the environment, but its measurement is laborious and expensive. We have explored the possibilities for monitoring N mineralization directly using time domain reflectometry (TDR). Net N and S mineralization were monitored over a 101-day period in two layers (0–30 and 30–60 cm) of a loamy sand soil during aerobic incubation in a laboratory experiment. At the same time electrical conductivity of the bulk soil, σa, was measured by TDR. A series of calibration measurements with different amounts of KNO3 at different soil moisture contents was made with the topsoil to calculate the electrical conductivity, σw, of the soil solution from σa and θ. The actual σw was determined from the conductivity of 1:2 soil:water extracts (σ1:2) with a mass balance approach using measured NO3– concentrations, after correction for ions present prior to the addition of KNO3. The average N mineralization rate in the topsoil was small (0.12 mg N kg−1 day−1), and, as expected, very small in the subsoil (0.023 mg N kg−1 day−1). In the top layer NO3– concentrations calculated from σa determined by TDR slightly underestimated measured concentrations in the first 4 weeks, and in the second half of the incubation there was a significant overestimation of measured NO3–. Using the sum of both measured NO3– and SO42– reduced the overestimation. In the subsoil calculated NO3– concentrations strongly and consistently overestimated measured concentrations, although both followed the same trend. As S mineralization in the subsoil was very small, and initial SO42– concentrations were largely taken into account in the calibration relations, SO42– concentrations could not explain the overestimation. The very small NO3– and SO42– concentrations in the B layer, at the lower limit of the concentrations used in the calibrations, are a possible explanation for the discrepancies. A separate calibration for the subsoil could also be required to improve estimates of NO3– concentrations.

Notes: Control of transcription in prokaryotes often involves direct contact of regulatory proteins with RNA polymerase. For the σ54 RNA polymerase, regulatory proteins bound to distally located enhancers engage the polymerase via DNA looping. The σ54-dependent nifA promoter of Herbaspirillum seropedicae (Hs) is activated under nitrogen-limiting growth conditions. Potential enhancers for the nitrogen control activators NTRC and NIFA and binding sites for integration host factor (IHF) and σ54-holoenzyme were identified. DNA footprinting experiments showed that these sites functioned for protein binding. Their involvement in the promoter regulation was explored. In vitro, activation of the Hs nifA promoter by NTRC is stimulated by the DNA bending protein IHF. In marked contrast, activation by NIFA is greatly reduced by IHF, thus diminishing potentially destabilizing autoactivation of the nifA promoter by NIFA. Additionally, high levels of NIFA appear to limit NTRC-dependent activation. This inhibition is IHF dependent. Therefore, IHF acts positively and negatively at the nifA promoter to restrict transcription activation to NTRC and one signal transduction pathway.

Notes: Haemophilus influenzae is an obligate commensal of the upper respiratory tract of humans that uses simple repeats (microsatellites) to alter gene expression. The mod gene of H. influenzae strain Rd has homology to DNA methyltransferases of type III restriction/modification systems and has 40 tetranucleotide (5′-AGTC) repeats within its open reading frame. This gene was found in 21 out of 23 genetically distinct H. influenzae strains, and in 13 of these strains the locus contained repeats. H. influenzae strains were constructed in which a lacZ reporter was fused to a chromosomal copy of mod downstream of the repeats. Phase variation occurred at a high frequency in strains with the wild-type number of repeats. Mutation rates were derived for similarly engineered strains, containing different numbers of repeats. Rates increased linearly with tract length over the range 17–38 repeat units. The majority of tract alterations were insertions or deletions of one repeat unit with a 2:1 bias towards contractions of the tract. These results demonstrate the number of repeats to be an important determinant of phase variation rate in H. influenzae for a gene containing a microsatellite.

Notes: : :Soymilk (SM), a potential culture medium for applying conductimetric techniques to evaluate the behavior of probiotic lactobacilli and bifidobacteria was examined. Media LAPTg, LM, and SM was standardized for the growth of Lactobacillus fermentum and Bifidobacterium longum. A dilution of 1/100 for L. fermentum and 1/1 for B. longum were considered optimal to obtain a detection time (DT) between 5 and 10 min. The relationship between the initial number of cells and the DT was linear throughout the incubation period considered (40 h). The effect of temperature (30, 37, and 42 °C) on the metabolic activity of the cells was also determined after 40 h of fermentation. The higher metabolic changes were observed at 42 °C with conductance values from 600 to 800 μS and DT of 5-7 min. Results obtained were confirmed by viable counts.

Notes: Different populations of Colletotrichum were characterized and quantified on floral parts of banana plants from flowering until harvest. Isolates of Colletotrichum found to be pathogenic and attributed to the species C. musae (77% of isolates) were differentiated from other species by abundant sporulation, a short mycelium, and rapid growth. Colletotrichum musae was isolated from floral parts mainly during the month following bunch emergence. The respective involvement of different sources of inoculum (leaves, bunch bracts, floral parts) in the levels of fruit contamination was evaluated. When the floral parts and bunch bracts were removed at flowering, the severity of anthracnose disease was considerably reduced. The severity of the disease is strongly correlated with cumulative rainfall during the first 35 days after bunch emergence, and was considerably reduced when rainwater runoff over the bunches was limited by placing plastic sleeves over them. The disease was not observed on banana fruit grown under shelters, protected from rain. The results obtained from this study show clearly that contamination of fruit by conidia takes place largely due to the trickling of rainfall over the floral parts, which are the main source of inoculum. The application of these results for integrated control is discussed.

Notes: Rabbit serum against the cysteine-proteinases papain has been employed for the cellular localization of cysteine-proteinases of in Leishmania amazonensis promastigotes. By immunocytochemistry, immune complexes were found in the plasma membrane and in the flagella pocket of the parasite. The antiserum immunoprecipitated major iodinated proteins with molecular masses of 66, 45, 28 and 24 kDa and a wide partitioning of the Triton X-114 detergent phase. The presence of cysteine-proteinase at the cell surface membrane was also suggested by the detection of proteolytic activity in living cells (19.0 μg azocasein min−1 10−7 promastigotes (1.0 S.D.)).