The influence of environmental management and animal shelters in vector control of Culicoides (Diptera,Ceratopogonidae) in northeastern Brazil

We investigated whether biting midges in peridomestic environments are affected by environmental management practices and the presence of domestic animals. We used CDC light traps to collect midges in 112 residences across 24 locations along tourism routes of Maranhão, Brazil. The collection areas were characterized as follows: i) peridomestic area with domestic animals and without management (dirty); ii) peridomestic with domestic animals and management (clean); iii) peridomestic without animals and with management (clean); iv) peridomestic without animals and without management (dirty). The first two treatments had higher biting midge species richness and abundance, respectively. Generalized linear models indicated a positive correlation between the presence of domestic animals and midge abundance, with an approximate four‐fold increase in Culicoides (Diptera: Ceratopogonidae) abundance in peridomestic areas with animals. The same model showed that domestic animals have no influence on richness. Environmental management does not appear to influence species richness or abundance of biting midges.     

Real-Time Imaging of the Axonal Transport of Granules Containing a Tissue Plasminogen Activator/Green Fluorescent Protein Hybrid

A hybrid protein, tPA/GFP, consisting of rat tissue plasminogen activator (tPA) and green fluorescent protein (GFP) was expressed in PC12 cells and used to study the distribution, secretory behavior, and dynamics of secretory granules containing tPA in living cells with a neuronal phenotype. High-resolution images demonstrate that tPA/GFP has a growth cone-biased distribution in differentiated cells and that tPA/GFP is transported in granules of the regulated secretory pathway that colocalize with granules containing secretogranin II. Time-lapse images of secretion reveal that secretagogues induce substantial loss of cellular tPA/GFP fluorescence, most importantly from growth cones. Time-lapse images of the axonal transport of granules containing tPA/GFP reveal a surprising complexity to granule dynamics. Some granules undergo canonical fast axonal transport; others move somewhat more slowly, especially in highly fluorescent neurites. Most strikingly, granules traffic bidirectionally along neurites to an extent that depends on granule accumulation, and individual granules can reverse their direction of motion. The retrograde component of this bidirectional transport may help to maintain cellular homeostasis by transporting excess tPA/GFP back toward the cell body. The results presented here provide a novel view of the axonal transport of secretory granules. In addition, the results suggest that tPA is targeted for regulated secretion from growth cones of differentiated cells, strategically positioning tPA to degrade extracellular barriers or to activate other barrier-degrading proteases during axonal elongation.     

In situ probing of Xylella fastidiosa in honeydew of a xylem sap-feeding insect using 16S rRNA-targeted fluorescent oligonucleotides

Xylella fastidiosa is a plant pathogen that threatens a US$ 4.6 billion worldwide wine and citrus industry. Monitoring its presence and distribution in plants and vectors is crucial for designing control strategies, as well as for understanding its ecological role and fate. We developed two fluorescent oligonucleotide probes complementary to different regions of the 16S rRNA gene of X. fastidiosa. The specificity of the newly designed probes S-S-X.fas-0067-a-A-18 and S-S-X.fas-1439-a-A-18 was demonstrated using fluorescence in situ hybridization (FISH) for 12 Xylella isolates, 15 closely related microorganisms and three plant endophytes. These probes were used to detect and quantify X. fastidiosa in plant sap (average value of 2.9 +/- 0.3 x 10(6) cells ml(-1)) from three different citrus orchards. In a second experiment, cells were quantified in honeydew (2.2 +/- 0.2 x 10(4) cells ml(-1)) collected from the insect vector Bucephalogonia xanthophis during the acquisition access period on an infected plant. The number of pathogen cells retained or digested by the insect is 10,000 times greater than the estimated minimum value to ensure an efficient transmission. Polymerase chain reaction (PCR) amplification using specific primers with plant sap and honeydew samples, followed by sequencing, confirmed the presence of the plant pathogen. This is the first demonstration of FISH being used for environmental samples, such as plant sap and insect honeydew, to estimate the abundance of a plant pathogen during infection.     

Sarcolemmal phospholipid fatty acid composition and permeability

In this study, the mechanism of ischaemia-induced increased sarcolemmal permeability, as manifested by release of intracellular enzymes, was investigated. The role of changes in the sarcolemmal phospholipid bilayer in this process was evaluated by experimental modulation of the phospholipid fatty acid composition. The isolated perfused rat heart subjected to low-flow hypoxia, was used as a model of global ischaemia. Glucose as well as saturated (palmitate) and unsaturated (linoleate) long-chain fatty acids were used as substrates. Hearts perfused with palmitate or linoleate (1.5 mM, fatty acid/albumin ratio, 3.4) showed a significantly higher rate of lactate dehydrogenase release in both control and ischaemic conditions than hearts perfused with glucose (10 mM). Lactate dehydrogenase release in the fatty acid-perfused hearts was associated with a significant increase in the percentage unsaturation of the sarcolemmal phospholipid fatty acids. Glucose-perfused hearts, on the other hand, showed only minor changes in the sarcolemmal phospholipid fatty acid composition. Attempts to correlate enzyme release directly with an increase in the percentage unsaturation of phospholipid fatty acids failed, since enzyme release was also stimulated in control fatty-acid-perfused hearts which (when compared with glucose) contained a higher percentage saturated phospholipid fatty acids. The results suggest that myocardial ischaemia, apart from changes in the sarcolemmal phospholipid fatty acid composition, also induces several other changes in sarcolemmal composition (e.g., cholesterol loss) which may affect is permeability for macromolecules.     

Inositolpolyphosphates and their binding proteins —a short review

Since 1983, when it was discovered that inositol 1,4,5-trisphosphate can act as second messenger to release Ca²⁺ from the endoplasmic reticulum, widespread research has focused on the phosphatidylinositol signalling transduction pathway and the host of inositolphosphates formed intracellularly after stimulation thereof. Although the polyphosphates, inositoltetrakisphosphate (InsP₄) and inositolhexakisphosphate (InsP₆), have received their share of attention, a definite physiological role has not been ascribed to them as yet. Different binding proteins for these two polyphosphates have been demonstrated, especially in brain tissue, indicating their possible importance in the cell.InsP₆ is known as one of nature's most powerful antioxidants and has already been demonstrated to possess the abilities to be of use in the industry as well as in the medical profession. As its natural actions are poorly understood and its possible side-effects have not been widely investigated, basic research regarding its cellular and subcellular activities is urgently called for.Recipient of Servier Investigator Award     

D2-dopaminergic blockade does not influence post-exercise ketosis in non-athletes

Metoclopramide has previously been shown to inhibit the ketosis of starvation in rats and humans. The effect of D2-dopaminergic blockade on post-exercise ketosis was, therefore, studied in 6 carbohydrate-starved non-athletic persons who had just completed a 9-km walk in mountainous terrain. There were nine control subjects who went on the walk, but who did not ingest metoclopramide. Metoclopramide (0.15 mg·kg⁻¹ body mass) caused a highly significant rise in the plasma prolactin concentration, but did not influence blood concentrations of 3-hydroxybutyrate, free fatty acid, glucose, insulin or glucagon. Unlike ketosis in starvation, therefore, neither prolactin, nor the D2-dopaminergic system play a part in the genesis of post-exercise ketosis.     

Early electrochemical events in lectin-lymphocyte interaction. I. Mechanism of lectin-mediated changes in the electrophoretic mobility of lymphocytes

Concanavalin A, at extremely low concentrations, will produce significant increases in the electrophoretic mobility of murine splenic T lymphocytes. It has been established that the alteration in cellular surface charge is mediated by a factor produced by those lymphocytes that have reacted directly with con A. We originally conjectured that the mobility change might be the consequence of an alteration in the distribution of the charged moieties of membrane glycoproteins. The results of experiments conducted at low temperature raise some questions about this mechanism. Further experiments have been performed to establish the nature of the physicochemical alterations in the peripheral zone of the factor-stimulated lymphocytes that are manifest as changes in cellular surface charge. The results of these studies indicate that, subsequent to the interaction of T lymphocytes with con A, there is a reduction in the number of positively charged amino groups effective at the electrophoretic surface of the cells.