Human cardiovascular and humoral responses to moderate muscle activation during dynamic exercise.

We examined the hypothesis that activation of the muscle metaboreflex during dynamic exercise would augment influences tending to cause a rise in arginine vasopressin, plasma renin activity, and catecholamines during dynamic exercise in humans. Ten healthy adults performed 30 min of supine cycle ergometer exercise at approximately 50% of peak oxygen consumption with or without moderate muscle metaboreflex activation by application of 35 mmHg lower body positive pressure (LBPP). Application of LBPP during the first 15 or last 15 min of exercise increased mean arterial blood pressure, plasma lactate concentration, and minute ventilation, indicating an activation of the muscle metaboreflex. These changes were rapidly reversed when LBPP was removed. During exercise at this intensity, LBPP augmented the release of arginine vasopressin and catecholamines but not of plasma renin activity. These results suggest that, although in humans hormonal responses are induced by moderate activation of the muscle metaboreflex during dynamic exercise, the thresholds for these responses may not be uniform among the various glands and hormones.     

Lucilia sericata Chymotrypsin Disrupts Protein Adhesin-Mediated Staphylococcal Biofilm Formation

Staphylococcus aureus and Staphylococcus epidermidis biofilms cause chronic infections due to their ability to form biofilms. The excretions/secretions of Lucilia sericata larvae (maggots) have effective activity for debridement and disruption of bacterial biofilms. In this paper, we demonstrate how chymotrypsin derived from maggot excretions/secretions disrupts protein-dependent bacterial biofilm formation mechanisms.     

Nutrient limitation of plant productivity in scrubby flatwoods: does fire shift nitrogen versus phosphorus limitation?

Differences in the biogeochemistry of nitrogen (N) and phosphorus (P) lead to differential losses and inputs during and over time after fire such that fire may affect nutrient limitation of primary productivity. We conducted a nutrient addition experiment in scrubby flatwoods, a Florida scrub community type, to test the hypothesis that nutrient limitation of primary productivity shifts from N limitation in recently burned sites to P limitation in longer unburned sites. We added three levels of N, P, and N and P together to sites 6 weeks, 8 years, and 20 years postfire and assessed the effects of nutrient addition on above- and belowground productivity and nutrient concentrations. At the community level, nutrient addition did not affect aboveground biomass, but root productivity increased with high N?+?P addition in sites 8 and 20 years after fire. At the species level, N addition increased leaf biomass of saw palmetto (Serenoa repens) in sites 6 weeks and 20 years postfire, while P addition increased foliar %P and apical shoot growth of scrub oak (Quercus inopina) in sites 8 and 20 years postfire, respectively. Contrary to our hypothesis, nutrient limitation does not appear to shift with time after fire; recently burned sites show little evidence of nutrient limitation, while increased belowground productivity indicates that scrubby flatwoods are co-limited by N and P at intermediate and longer times after fire.     

Decomposition of Senesced Leaf Litter is Faster in Tall Compared to Low Birch Shrub Tundra

Many Low Arctic tundra regions are currently undergoing a vegetation shift towards increasing growth and groundcover of tall deciduous shrubs due to recent climate warming. Vegetation change directly affects ecosystem carbon balance, but it can also affect soil biogeochemical cycling through physical and biological feedback mechanisms. Recent studies indicate that enhanced snow accumulation around relatively tall shrubs has negligible physical effect on litter decomposition rates. However, these investigations were no more than 3 years, and therefore may be insufficient to detect differences in inherently slow biogeochemical processes. Here, we report a 5-year study near Daring Lake, Canada, comparing Betula neoalaskana foliar litter decay rates within unmanipulated and snowfenced low-stature birch (height: ~?0.3 m) plots to test the physical effect of experimentally deepened snow, and within tall birch (height: ~?0.8 m) plots to test the combined physical and biological effects, that is, deepened snow plus strong birch dominance. Having corrected for carbon gain by the colonizing decomposers, actual litter carbon loss increased by approximately 25% in the tall birch relative to both low birch sites. Decay of lignin-like acid unhydrolizable litter residues also accelerated in the tall birch site, and a similar but lower magnitude response in the snowfenced low birch site indicated that physical effects of deepened snow were at least partially responsible. In contrast, deepened snow alone did not affect litter carbon loss. Our findings suggest that a combination of greater litter inputs, altered soil microbial community, enhanced soil nutrient pools, and warmer winter soils together promote relatively fast decomposition of recalcitrant litter carbon in tall birch shrub environments.     

Patchwork, Pastoralists, and Perception: Dune Sand as a Valued Resource Among Herders of Inner Mongolia

Scholars have rarely reflected upon dune sand in any context other than that of environmental hazard. Yet recent anthropological research conducted among ethnic Mongol herders in the Keerqin Sandy Lands of Northeast China indicates that native inhabitants exhibit a surprising degree of tolerance, appreciation, and even preference for dune sand at specific spatio-temporal scales. Survey data, gathered primarily through the use of photographic prompts and pile sort exercises during household interviews, reveal that many residents even regard dune sand as the constituent element of a distinctive home environment and cherished way of life. This research underscores the relevance of perception to the policies and practices of human resource management. It also calls into question the authority with which officials and scholars in China and elsewhere indiscriminantly depreciate the various social utilities of dune sand in stock-herding populations.     

Metabolic Consequences of Altered PhosphoenolpyruvateCarboxykinase Activity in Corynebacterium glutamicum Reveal Anaplerotic Regulation Mechanisms in Vivo

Corynebacterium glutamicum possesses high in vivo activity of the gluconeogenic phosphoenolpyruvate carboxykinase (PEPCk) during growth on glucose, resulting together with anaplerotic carboxylation reactions in a PEP/pyruvate/oxaloacetate substrate cycle. The present study investigated the changes in intracellular fluxes and metabolite concentrations that are caused by altered PEPCk activity in L-lysine-producing C. glutamicum MH20-22B, applying a recently developed (13)C labeling-based strategy for anaplerotic flux resolution and quantification. Abolition of PEPCk activity by deletion of the respective pck gene resulted in increased intracellular concentrations of oxaloacetate L-aspartate, alpha-ketoglutarate, pyruvate, and L-lysine and in a 60% enhanced flux toward L-lysine biosynthesis, whereas increasing the PEPCk activity by pck overexpression had opposite effects. The results of the combined measurements of enzyme activities, in vivo fluxes, and metabolite concentrations were exploited to elucidate the in vivo regulation of anaplerotic reactions in C. glutamicum, and implications for the metabolic engineering of amino-acid-producing strains are discussed.     

Pet Snakes as a Reservoir for Salmonella enterica subsp. diarizonae (Serogroup IIIb): a Prospective Study

Reptile-associated Salmonella infections are an increasing problem for humans. We have prospectively screened two breeding groups of 16 pet snakes for colonization with Salmonella species. Various serovars of S. enterica subsp. diarizonae were found in 81% of the snakes. To avoid transmission, strict hygienic precautions should be applied when reptiles are handled.     

Selective photoreactions in a programmable array microscope (PAM): photoinitiated polymerization, photodecaging, and photochromic conversion.

BACKGROUND: Innovative thinking and experimentation were the hallmarks of Mack Fulwyler's approach to research. This report summarizes some of the ideas and their early realizations that he pursued in the field of imaging cytometry, work that was not published before his untimely death, although he composed the initial draft of this report. METHODS: Included are related experiments implemented in the programmable array microscope (PAM) devised for patterned illumination and detection, the instrument that Mack Fulwyler employed during a sabbatical leave in G?ttingen in 1998. Despite being the originator of instrumentation for flow cytometry and sorting, Mack Fulwyler was intensely interested in imaging systems, recognizing their ability to resolve cellular details obscured by the whole cell signals generally acquired in flow. At one point, these interests merged with those of two other authors (I.T.Y. and T.M.J.), leading to the Image Cytometry and Sorting (ICAS) strategy and project. A major goal was uncomplicated rare cell detection and isolation using a sequential process of cellular labeling via suitable probes, whole field imaging, and selective area-restricted photoinduced reactions designed to encapsulate and/or chemically or physically tag cells in a manner permitting subsequent fractionation by bulk techniques. RESULTS AND CONCLUSION: This publication features photoinduced polymerization, photodecaging, photoactivation, and photochromic conversion reactions carried out by Fulwyler and/or the other authors with the PAM, employing operator designated patterns and locations in various samples. Photopolymerization of polyethylene glycol-diacrylate to a gel-like structure allowing the specific selection of objects (cells) for further analysis and processing techniques was the approach explored personally by Mack Fulwyler in relation to the ICAS concept.