Foliar fungi alter reproductive timing and allocation in Arabidopsis under normal and water-stressed conditions

ABSTRACTMicrobes influence plant phenotypes but most known examples of this are from the study of below-ground microbes and plant disease modification. To examine the potential importance of phyllosphere microbes on non-disease related plant traits, we used sterile Arabidopsis clones to test the effects of foliar fungi on flowering phenology and reproductive allocation under conditions of varying water stress. We inoculated the sterile plants with fully-factorial combinations of four fungal isolates, then measured flowering time and reproductive allocation for each treatment group under normal and water-stressed conditions. All plants inoculated with foliar fungi had significantly later flowering and greater seed mass than the sterile control groups. The magnitude of this effect depended on the specific fungi present, but individual fungal effects diminished as inoculum richness increased. Above-ground microbes likely influence other plant traits as well and should be considered in any study measuring plant phenotypes.

Looking Beyond the Gesture: Vocabulary Acceptability Criteria for Gesture Elicitation Studies

The choice of what gestures should be part of a gesture language is a critical step in the design of gesturebased interfaces. This step is especially important when time and accuracy are key factors of the user experience, such as gestural interfaces in vehicle control and sterile control of a picture archiving and communication system (PACS) in the operating room (OR). Agreement studies are commonly used to find the gesture preference of the end users. These studies hypothesize that the best available gesture lexicon is the one preferred by a majority. However, these agreement approaches cannot offer a metric to assess the qualitative aspects of gestures. In this work, we propose an experimental framework to quantify, compare and evaluate gestures. This framework is grounded in the expert knowledge of speech and language professionals (SLPs). The development consisted of three studies: 1) Creation, 2) Evaluation and 3) Validation. In the creation study, we followed an adapted version of the Delphi’s interview/discussion procedure with SLPs. The purpose was to obtain the Vocabulary Acceptability Criteria (VAC) to evaluate gestures. Next, in the evaluation study, a modified method of pairwise comparisons was used to rank and quantify the gestures based on each criteria (VAC). Lastly, in the validation study, we formulated an odd one out procedure, to prove that the VAC values of a gesture are representative and sufficiently distinctive, to select that particular gesture from a pool of gestures. We applied this framework to the gestures obtained from a gesture elicitation study conducted with nine neurosurgeons, to control an imaging software. In addition, 29 SLPs comprising of 17 experts and 12 graduate students participated in the VAC study. The best lexicons from the available pool were obtained through both agreement and VAC metrics. We used binomial tests to show that the results obtained from the validation procedure are significantly better than the baseline. These results verify our hypothesis that the VAC are representative of the gestures and the subjects should be able to select the right gesture given its VAC values.

Pyrite Oxidation by Moderately Thermophilic Microorganisms

The goal of the present work was to compare the rates of pyrite oxidation by different microorganisms, representatives of the groups predominating in biohydrometallurgical processes. The experiments were conducted in flasks with 100 mL of the medium containing mineral salts, 0.02% of yeast extract, and 2 g of pyrite at 45°C on rotation shaker (200 rpm) for 30 days. Strains Acidithiobacillus caldus MBC-1, Sulfobacillus thermosulfidooxidans VKMV 1269T, and Acidiplasma sp. MBA-1 were used in the study. Different combinations of the strains were used in the experiments (pure cultures of S. thermosulfidooxidans VKMV 1269T, Aсidiplasma sp. MBA-1, A. caldus MBC-1, as well as mixed cultures S. thermosulfidooxidans VKMV 1269T + A. caldus MBC-1, Aсidiplasma sp. MBA-1 + A. caldus MBC-1, S. thermosulfidooxidans VKMV 1269T + Aсidiplasma sp. MBA-1). Iron concentrations in the medium were the highest in the variants “S. thermosulfidooxidans VKMV 1269T + A. caldus MBC-1”, “Aсidiplasma sp. MBA-1 + A. caldus MBC-1”, and “Sb. thermosulfidooxidans VKMV 1269T + Aсidiplasma sp. MBA-1” and achieved 3.8, 3.5, and 3.3 g/L, respectively. Iron concentration in sterile control as well as in the experiments with pure cultures of Aсidiplasma sp. MBA-1 and A. caldus MBC-1 were very low. It demonstrated that in these variants pyrite was almost not oxidized. In the experiment with the pure culture of S. thermosulfidooxidans VKMV 1269T, the rate of oxidation was high during 10 d of the experiment but then the oxidation activity drastically decreased. The ferric iron concentration achieved a maximum of 1.8 g/L and then decreased, whereas the ferrous iron concentration began to increase. Revealed differences in pyrite oxidation rates can be explained by differences in the physiological properties between the microorganisms. Results of the present work suggest that different groups of microorganisms have different impact in pyrite biooxidation.

Oxidative Capacity of Native Strains from Copahue Geothermal System in the Pretreatment of a Gold Sulfide Ore

In this report we evaluate the oxidative capacity of native microorganisms from Copahue geothermal system applied to a gold concentrate (71.1 g/t) compared to that showed by some culture collection strains. The sulphide ore, in which gold is present as submicroscopic particles contained in a pyrite matrix, came from several reservoirs of polymetallic ores located in Neuquén, Patagonia Argentina. The ore was processed in Andacollo treatment plant for gold concentration. After biooxidation tests, the highest percentages of solubilised iron were reached in the inoculated system (100% mixed native cultures, 47.8% Leptospirillum ferrooxidans ATCC 29047 and 28.5% for Acidithiobacillus ferrooxidans DSM 11477) while in the sterile control it was only 8.8%. The gold recovery was 96.3% and 45.3% for the treated and untreated concentrate respectively.

Effects of Water Stress on Colonization of Poplar Stems and Excised Leaf Disks by Septoria musiva

Septoria musiva causes leaf spot and canker diseases of trees in the genus Populus, and is one of the most damaging fungal pathogens of hybrid poplar in eastern North America. The effect of host water stress on Septoria canker development was studied in two separate greenhouse experiments. Hybrid poplar clones NM6, NC11396, and NE308 were stressed by withholding water until predawn water potential fell below −1.0 MPa. Stems were treated by removing a leaf and applying agar plugs that were either colonized by S. musiva (inoculated) or sterile (control) to the wound. Cankers on inoculated water-stressed trees were significantly larger than those on nonstressed trees. A leaf disk assay also was conducted three times with the NM6 and NE308 trees. We cut two disks from each of 120 stressed and 120 well-watered trees, placing them on water agar in 24-well tissue culture plates. A conidial suspension was applied to one disk in each pair and sterile water to the other. Inoculated disks from water-stressed trees developed less necrosis than those from well-watered trees. These results demonstrate that environmental influences on host condition must be considered in evaluating resistance of clones proposed for widespread culture of hybrid poplar.

The mineral nutrient composition of wheat grains from ears grown to maturity in the field or cultured in media containing different concentrations of P, Mg, K and Ca

A study was conducted to assess the effect of the supply of phosphorus and the major cations on the mineral nutrient composition of whole mature wheat grains and the electron-dense globoid crystals found in the aleurone cells. Ears of wheat plants, growing in the field, were detached after anthesis. The ears were cultured to maturity in a sterile control solution which contained all essential elements. Other ears were cultured in solutions which contained no phoshorus, no calcium, no magnesium, combinations of these (−P, −Ca; −P, −Mg) or a solution which contained additional potassium but no phosphorus, calcium or magnesium. Ears cultured in the control solution produced grains with higher concentrations of P, Mg, K and Ca than grains from ears which matured on plants in the field. All the −P treatments produced grains with lower concentrations of P and higher concentrations of Mg, K and Ca than the plants grown in the field. The appearance and elemental composition of the globoid crystals in the aleurone cells support the hypotheses that the size of globoid crystals is regulated, in part, by the amount of phosphorus deposited in the grain and also by the relative proportions of K, Mg and Ca in the tissue. The culture of individual ears of cereal plants is a useful technique by which to study the transfer to and deposition of mineral nutrients in cereal grains.

Use of Sputter-Deposited 316L Stainless Steel Ultrathin Films for Microbial Influenced Corrosion Studies

ABSTRACTUltra thin films (12nm) were sputter deposited onto cylindrical germanium internal reflection elements pre-coated with a thin (2nm) layer of Cr2O3. Two crystals were inserted into Circle cell flow-through chambers and mounted on the optical bench of an Fourier Transform Infrared (FT-IR) spectrometer. One chamber was maintained as a sterile control while the other was sequentially inoculated with four bacterial species:Pseudomonas aeruginosa, Bacillus subtillis, Hafnia alvei, andDesulfovibrio gigas, in that order. The water absorption band (1640cm−1) was monitored and used to follow the deterioration of the ultra thin films. In this respect, the sterile control and inoculated films exhibited only slight differences during the 1000h course of the experiment. Assay of the visible biofilm that had accumulated on the surface of the inoculated crystal after 1000h revealed that the film incorporated viable cells from all four strains.

Biodegradation of pentachlorophenol in soil: the response to physical, chemical, and biological treatments

The effects of physical, chemical, and biological treatments on biodegradation of pentachlorophenol (PCP) were studied in a silt-loam soil contaminated with 175 mg PCP/kg and uniformly 14C-labelled PCP. Biodegradation of 14C-labelled PCP and technical-grade PCP were monitored over 210 days incubation. Mineralization of labelled PCP was significantly (p = 0.05) influenced by soil treatments. Negligible biodegradation occurred in either the sterile control soil or the uninoculated control soil, with less than 1% of added 14C recovered as 14CO2. Inoculation of unamended soil with a strain of Flavobacterium (ATCC 39723) known to degrade PCP increased biodegradation of PCP; approximately 60% of the [14C]PCP was recovered as 14CO2. Increased soil water content (60% versus 30%, w/w) enhanced biodegradation (67% recovery of 14C as CO2), while increased chloride ion concentration and anoxic conditions were inhibitory (20 and 1% recoveries, respectively). Residual soil PCP concentrations were also influenced by various treatments. In the sterile control soil and noninoculated control, after 210 days incubation, concentrations of PCP were 143 and 123 mg/kg, respectively, while the PCP concentration in the inoculated soil was 21 mg/kg. When soil organic matter was increased by adding finely ground red clover leaf and stem material, the residual PCP concentration was reduced to 6 mg/kg after 210 days. Increased soil water content resulted in a residual PCP concentration of 5 mg/kg. High-pressure liquid chromatography of soil extracts revealed no accumulation of partial PCP degradation products. These results indicated that biodegradation of PCP in soil was significantly influenced by various soil amendments. Key words: biodegradation, pentachlorophenol, soil, Flavobacterium.

Bacteriologie Studies on Electronic Hospital Thermometers

Electronic thermometers used in many hospitals require insertion into the mouth of a temperature-sensing probe covered by a pre-packaged probe cover. Handling procedures used by hospital personnel can lead to inadvertent manual contact with the probe cover. We attempted to determine the rate of non-sterility of these probe covers under normal hospital conditions and the extent to which pathogens could be detected on these and other components of the thermometer. Probe covers were removed before entry into the patient's mouth and aseptically inoculated into fluid thioglycollate medium. Subcultures were made to appropriate differential media. Over a 13-week period, 180 covers were cultured on two private hospital services. Forty-three percent were found to be non-sterile; control covers from central supply were only 6% non-sterile. Four percent of the probe covers harbored potential pathogens: coagulase positive Staphylococcus aureus, Streptococcus pyogenes, Enterobacter, and Bacteroides. No attempt was made to correlate these findings with infection. These results indicated a potential infection hazard for high-risk patient groups and a need by hospital personnel to consider this as a possible source of contamination [Infect Control 1981; 2(4):315-6.]

Pathophysiology of gas exchange and pulmonary perfusion in pneumococcal lobar pneumonia in dogs

We placed an inoculum of Streptococcus pneumoniae type III into a left lower lobe bronchus of six dogs (group P), and in six other dogs (Group C) a sterile control inoculum was used. Measurements of shunt (Qs/Qt) and venous admixture (Qva/Qt) were made immediately before (day 1) and 48 h after (day 3) inoculation. All dogs in group P had extensive lobar pneumonia confirmed radiologically and at autopsy, whereas Group C had only small sterile lesions at the site of inoculation. In group P, mean Qs/Qt and Qva/Qt increased significantly to 0.15 and 0.21, respectively. Mean lobar Qs/Qt, calculated using blood samples from lobar veins at thoracotomy on day 3, was markedly increased in the pneumonia lobe (0.69) compared with the contralateral lower lobe (0.08), and alveolar ventilation of that lobe approached zero. Perfusion of the infected lobe determined by radioactive microspheres showed a variable and statistically nonsignificant decrease between control and infected states that was not affected by oxygen breathing. In group C there was no change between days 1 and 3 in gas exchange or in distribution of pulmonary perfusion. We conclude that hypoxemia in pneumonia was due to both increased shunt and venous admixture in the infected regions, and that local hypoxic vasoconstriction was in most instances ineffective in directing blood flow away from the consolidated lobe.