Abundance and Activity of 16S rRNA,AmoA and NifH Bacterial Genes During Assisted Phytostabilization of Mine Tailings

Mine tailings in semiarid regions are highly susceptible to erosion and are sources of dust pollution and potential avenues of human exposure to toxic metals. One constraint to revegetation of tailings by phytostabilization is the absence of microbial communities critical for biogeochemical cycling of plant nutrients. The objective of this study was to evaluate specific genes as in situ indicators of biological soil response during phytoremediation. The abundance and activity of 16S rRNA, nifH, and amoA were monitored during a nine month phytostabilization study using buffalo grass and quailbush grown in compost-amended, metalliferous tailings. The compost amendment provided a greater than 5-log increase in bacterial abundance, and survival of this compost-inoculum was more stable in planted treatments. Despite increased abundance, the activity of the introduced community was low, and significant increases were not detected until six and nine months in quailbush, and unplanted compost and buffalo grass treatments, respectively. In addition, increased abundances of nitrogen-fixation (nifH) and ammonia-oxidizing (amoA) genes were observed in rhizospheres of buffalo grass and quailbush, respectively. Thus, plant establishment facilitated the short term stabilization of introduced bacterial biomass and supported the growth of two key nitrogen-cycling populations in compost-amended tailings.     

A Single-fly Assay for Foraging Behavior in Drosophila

For many animals, hunger promotes changes in the olfactory system in a manner that facilitates the search for appropriate food sources. In this video article, we describe an automated assay to measure the effect of hunger or satiety on olfactory dependent food search behavior in the adult fruit fly Drosophila melanogaster. In a light-tight box illuminated by red light that is invisible to fruit flies, a camera linked to custom data acquisition software monitors the position of six flies simultaneously. Each fly is confined to walk in individual arenas containing a food odor at the center. The testing arenas rest on a porous floor that functions to prevent odor accumulation. Latency to locate the odor source, a metric that reflects olfactory sensitivity under different physiological states, is determined by software analysis. Here, we discuss the critical mechanics of running this behavioral paradigm and cover specific issues regarding fly loading, odor contamination, assay temperature, data quality, and statistical analysis.     

Diabetes mellitus and the exocrine pancreas

Diabetes and carbohydrate intolerance can occur in pancreatitis. Although one-half of patients with acute pancreatitis will have some evidence of glucose intolerance during their acute illness, few will require insulin administration on either a short- or long-term basis. The diabetes seen in acute pancreatitis is likely due to a combination of factors, including alerted insulin secretion, increased glucagon release, and decreased glucose utilization by the liver and peripheral tissue. Chronic pancreatitis is often associated with diabetes mellitus, with the incidence as high as 70 percent when pancreatic calcification is present. These patients tend to be very sensitive to the effects of insulin and hypoglycemia. This is probably secondary to concurrent hepatic disease, malnutrition, and a relative decrease in glucagon reserves. The diabetes seen in chronic pancreatitis is associated with decreased insulin production. Finally, although the endocrine pancreas may influence the exocrine gland through a portal system, primary diabetes mellitus probably does not result in clinically significant alterations in pancreatic exocrine function.     

The Chilean Espinal: Restoration for a Sustainable Silvopastoral System

The mediterranean habitats of central Chile are rich in endemic species, but threatened by land‐use changes. In this context, we suggest that restoration of the traditional espinal silvopastoral system could improve its sustainability and conservation value. Past research on the espinal embraced negative stereotypes of peasants, the tree Acacia caven, and the semiarid landscape to recommend abandoning the silvopastoral system. We think that recommendation is premature and ignores the value of the espinal as a classical Chilean cultural landscape. Drawing on lessons from silvopastoral systems in Latin America and the Mediterranean, here we suggest several management interventions and incentives that could be developed to restore the espinal. Particular challenges in espinal include low biomass production due to the semiarid climate and the lack of a traditional sustainable timber or non‐timber product of A. caven. Our recommendations include sustainable production and use of biochar and bark extracts from A. caven to improve espinal soils, the promotion of shrubs and the use of small mammal disturbances, and their artificial analogs to improve A. caven reproduction, and rotational livestock herding to form mosaic landscapes. These techniques could lead to higher forage biomass and increased livestock weights. Incentive structures to implement these management activities could include tax benefits for private protected area (IUCN category VI) creation, REDD+ and PES programs, along with promotion of the cultural value of the espinal. Further research is urgently called for on ecosystem services, ecological baselines, biochar, and other management and incentive structures that could be applied in the espinal.     

Alcohol and Acute Pancreatitis

Alcohol abuse is associated with the development of both acute and chronic pancreatitis. The majority of patients who abuse alcohol will not develop pancreatitis; the reasons for different susceptibilities to alcohol are unknown. Most patients who present with acute alcoholic pancreatitits will have underlying chronic disease, but up to a third will have no evidence of chronic pancreatitis. Alcohol has a number of acute effects on the pancreas that are potentially toxic. These include increasing pancreatic duct pressure, decreasing pancreatic blood flow, generating free radicals, and stimulating pathologic zymogen activation within the pancreatic acinar cell.     

D-Penicillamine: analysis of the mechanism of copper-catalyzed hydrogen peroxide generation

Recent studies have suggested that the inhibition of lymphocyte mitogenesis by D-penicillamine in the presence of copper could be mediated by the formation and action of hydrogen peroxide. To explore this possibility further, we first sought evidence of H2O2 generation by D-penicillamine in a cell-free system by a) measurement of copper-catalyzed D-penicillamine oxidation and the requirement for oxygen in this process; b) direct measurement of H2O2 formation during D-penicillamine oxidation by the peroxidase-mediated oxidation of fluorescent scopoletin; and c) evaluation of the possible synthesis of O2- during D-penicillamine oxidation. The addition of copper to D-penicillamine in physiologic buffer catalyzed D-penicillamine oxidation in a dose-dependent fashion. D-penicillamine oxidation was accompanied by O2 consumption with a molar ratio of approximately 2:1, but did not occur under anaerobic conditions. Furthermore, D-penicillamine oxidation resulted in the formation of amounts of H2O2 stoichiometrically equivalent to oxygen consumption (i.e., 1:1). Copper-catalyzed D-penicillamine oxidation caused reduction of nitroblue tetrazolium in a reaction blocked by superoxide dismutase, suggesting the formation of O2-. Additional studies confirmed that D-penicillamine inhibited PHA-induced mitogenesis of lymphocytes in the presence of copper, and that catalase protected the cells from this action. Furthermore, when polymorphonuclear leukocytes were incubated with D-penicillamine plus copper, hexose monophosphate shunt activity increased up to threefold with abrogation of this stimulation by catalase. None of the effects of D-penicillamine plus copper on cells were diminished by hydroxyl radical scavengers mannitol or benzoate. These results are consistent with oxygen-dependent copper-catalyzed oxidation of D-penicillamine in aqueous solutions leading to the formation of O2- and H2O2. H2O2 produced by this reaction can inhibit lymphocyte mitogenesis and stimulate neutrophil hexose monophosphate shunt activity in vitro and may be relevant to the therapeutic effects of D-penicillamine in vivo.     

A Procedure for Implanting Organized Arrays of Microwires for Single-unit Recordings in Awake,Behaving Animals

In vivo electrophysiological recordings in the awake, behaving animal provide a powerful method for understanding neural signaling at the single-cell level. The technique allows experimenters to examine temporally and regionally specific firing patterns in order to correlate recorded action potentials with ongoing behavior. Moreover, single-unit recordings can be combined with a plethora of other techniques in order to produce comprehensive explanations of neural function. In this article, we describe the anesthesia and preparation for microwire implantation. Subsequently, we enumerate the necessary equipment and surgical steps to accurately insert a microwire array into a target structure. Lastly, we briefly describe the equipment used to record from each individual electrode in the array. The fixed microwire arrays described are well-suited for chronic implantation and allow for longitudinal recordings of neural data in almost any behavioral preparation. We discuss tracing electrode tracks to triangulate microwire positions as well as ways to combine microwire implantation with immunohistochemical techniques in order to increase the anatomical specificity of recorded results.     

A new method for the noninvasive determination of abdominal muscle feedforward activity based on tissue velocity information from tissue Doppler imaging.

Rapid arm movements elicit anticipatory activation of the deep-lying abdominal muscles; this appears modified in back pain, but the invasive technique used for its assessment [fine-wire electromyography (EMG)] has precluded its widespread investigation. We examined whether tissue-velocity changes recorded with ultrasound (M-mode) tissue Doppler imaging (TDI) provided a viable noninvasive alternative. Fourteen healthy subjects rapidly flexed, extended, and abducted the shoulder; recordings were made of medial deltoid (MD) surface EMG and of fine-wire EMG and TDI tissue-velocity changes of the contralateral transversus abdominis, obliquus internus, and obliquus externus. Muscle onsets were determined by blinded visual analysis of EMG and TDI data. TDI could not distinguish between the relative activation of the three muscles, so in subsequent analyses only the onset of the earliest abdominal muscle activity was used. The latter occurred <50 ms after the onset of medial deltoid EMG (i.e., was feedforward) and correlated with the corresponding EMG onsets (r = 0.47, P < 0.0001). The mean difference between methods was 20 ms and was likely explained by electromechanical delay; limits of agreement were wide (-40 to +80 ms) but no greater than those typical of repeated measurements using either technique. The between-day standard error of measurement of the TDI onsets (examined in 16 further subjects) was 16 ms. TDI yielded reliable and valid measures of the earliest onset of feedforward activity within the anterolateral abdominal muscle group. The method can be used to assess muscle dysfunction in large groups of back-pain patients and may also be suitable for the noninvasive analysis of other deep-lying or small/thin muscles.