Microbiology of Oil Fly Larvae

One animal beautifully adapted to the viscous asphalt of the La Brea tar pits is the oil fly Helaeomyia petrolei (Syn. Psilopa). As a normal part of its carnivorous existence the oil fly larval guts are filled with tar, with no adverse effects. Surface sterilized larvae 5 contained ca. 2 x 10 heterotrophic bacteria per larva. These bacteria have been identified as a mixture of enteric bacteria, most commonly Providencia rettgeri, and Acinetobacter spp. These bacteria were clearly growing because their numbers in the larval guts were 100 to 1,000 times greater than in free oil/asphalt. There is no evidence yet that these bacteria can degrade the complex aromatic hydrocarbons of the tar/asphalt. However, the bacteria isolated are highly solvent tolerant and they remain a potential source of hydrocarbon/solvent tolerant enzymes. Likely of greatest evolutionary interest, these bacteria were naturally resistant to 9 of 23 common antibiotics tested. This finding suggests that the oil fly bacteria have an active efflux pump for aromatic hydrocarbons, due to the constant selective pressure of La Brea’s solvent-rich environment. We suggest that the oil fly bacteria and their genes for solvent tolerance may provide a microbial reservoir for antibiotic resistance genes

Dynamic Surface Tension Behaviour in a Photoresponsive Surfactant System

We report on the surface properties of a photoresponsive surfactant that incorporates the light-sensitive azobenzene group into its tail. Cis-trans photo-isomerization of this group alters the ability of the surfactant to pack into adsorbed monolayers at an air-water interface or into aggregates in solution, causing a significant variation in bulk and surface properties upon changes in the illumination conditions. NMR studies indicate that a solution left in the dark for an extended period of time contains trans isomer almost exclusively, while samples exposed to light of fixed wavelength eventually reach a photostationary equilibrium with significant amounts of both isomers present. Dynamic surface tension studies performed on this system under different illumination conditions (dark, UV light, visible light) show profoundly different approaches to equilibrium. At concentrations well above the CMC, the same equilibrium tension is reached in all three cases, presumably corresponding to a surface saturated with the trans (more surface active) isomer. The dark sample shows a simple, single-step relaxation in surface tension after creation of a fresh interface, while the UV and visible samples exhibit a more rapid initial decrease in tension, followed by a plateau of nearly constant tension, and end with a final relaxation to equilibrium. It is hypothesized that this behavior of the UV and visible samples is caused by competitive adsorption between the cis and trans isomers present in these mixtures. Presumably the cis surfactant reaches the interface more quickly, leading to a cis-dominated interface having a tension value corresponding to the intermediate plateau, but is ultimately displaced by the trans isomer. Diffusional time scale arguments which consider the extremes of possible micellar dissolution rates are used to analyze the relaxation data of the dark sample, and the results indicate that micellar dissolution in these samples is slow.Singapore-MIT Alliance (SMA

Anthrax lethal toxin induced lysosomal membrane permeabilization and cytosolic cathepsin release is Nlrp1b/Nalp1b-dependent.

NOD-like receptors (NLRs) are a group of cytoplasmic molecules that recognize microbial invasion or 'danger signals'. Activation of NLRs can induce rapid caspase-1 dependent cell death termed pyroptosis, or a caspase-1 independent cell death termed pyronecrosis. Bacillus anthracis lethal toxin (LT), is recognized by a subset of alleles of the NLR protein Nlrp1b, resulting in pyroptotic cell death of macrophages and dendritic cells. Here we show that LT induces lysosomal membrane permeabilization (LMP). The presentation of LMP requires expression of an LT-responsive allele of Nlrp1b, and is blocked by proteasome inhibitors and heat shock, both of which prevent LT-mediated pyroptosis. Further the lysosomal protease cathepsin B is released into the cell cytosol and cathepsin inhibitors block LT-mediated cell death. These data reveal a role for lysosomal membrane permeabilization in the cellular response to bacterial pathogens and demonstrate a shared requirement for cytosolic relocalization of cathepsins in pyroptosis and pyronecrosis

Fiber-optic three axis magnetometer prototype development

The goal of this research program was to develop a high sensitivity, fiber optic, interferometric, three-axis magnetometer for interplanetary spacecraft applications. Dynamics Technology, Inc. (DTI) has successfully integrated a low noise, high bandwidth interferometer with high sensitivity metallic glass transducers. Also, DTI has developed sophisticated signal processing electronics and complete data acquisition, filtering, and display software. The sensor was packaged in a compact, low power and weight unit which facilitates deployment. The magnetic field sensor had subgamma sensitivity and a dynamic range of 10(exp 5) gamma in a 10 Hz bandwidth. Furthermore, the vector instrument exhibited the lowest noise level when only one axis was in operation. A system noise level of 1 gamma rms was observed in a 1 Hz bandwidth. However, with the other two channels operating, the noise level increased by about one order of magnitude. Higher system noise was attributed to cross-channel interference among the dither fields

Geometry of Empty Space is the Key to Near-Arrest Dynamics

We study several examples of kinetically constrained lattice models using dynamically accessible volume as an order parameter. Thereby we identify two distinct regimes exhibiting dynamical slowing, with a sharp threshold between them. These regimes are identified both by a new response function in dynamically available volume, as well as directly in the dynamics. Results for the selfdiffusion constant in terms of the connected hole density are presented, and some evidence is given for scaling in the limit of dynamical arrest.Comment: 11 page

Diurnal Distribution of Very Heavy Precipitation Over the Central and Eastern United States

A climatology of heavy precipitation events for the states of Nebraska, Missouri, Illinois, Kentucky, Tennessee, West Virginia, Pennsylvania, and Virginia is developed from 10 years (1968-1977) of Hourly Precipitation Data. Hourly precipitation events are categorized by severity, ranging from 1 to 2 inches (2.5 to 5.1 cm) in one hour or less (Type 1) to 4 or more inches (greater than 10.2 cm) in eight hours or less (Type 4). Hourly distributions of heavy precipitation events indicate that intense rainfalls of short duration occur most frequently during the afternoon and evening hours; whereas Type 4 events, which pose the most serious threat of flash flooding occur most often during the night and early morning hours in the central and eastern United States

Adoption of site-specific variable rate sprinkler irrigation systems

More than 20 years of private and public research on site-specific variable rate sprinkler irrigation (SS-VRI) technology on self-propelled center pivot and linear move irrigation systems has resulted in limited commercial adoption of the technology. Competing patents, liability, and proprietary software have affected industry’s willingness to move into a new technology area. Documented and proven water conservation strategies using site specific irrigation are quite limited. Marginal costs associated with site-specific technologies are high. Although sales of SS-VRI are increasing, they are primarily being used for eliminating irrigation and chemigation on non-cropped areas of a field or for land application of liquid agricultural and municipal wastes. Various aspects of SS-VRI technologies for general crop production are beginning to slowly gain widespread acceptance; however, their uses are largely focused on addressing symptoms of poor design and suboptimal water and nutrient management. Although currently underutilized, SS-VRI technology has the potential to positively impact crop water productivity, water and energy conservation, and the environment. There are also few economic incentives to motivate growers to move to higher levels of SS-VRI management. Greater adoption rates will likely require higher costs for water and energy, severely restricted water diversions on a broad scale, and enforcement of compliance with environmental and other regulations. Sustainable use of SS-VRI will require strong research support, which is currently limited. In the short term, adoption of SS-VRI technologies will be enhanced by addressing equipment deficiencies and research developing basic criteria and systems for defining management zones and locations of various sensor systems for both arid and humid regions. Training adequate personnel to help write site-specific variable rate irrigation prescriptions in humid and arid areas to assist growers with the decision-making process is also a high priority. There is also a large need to educate government boards and bankers on the potential benefits of these systems. The long-term challenges will be to demonstrate that SS-VRI will improve water management or increase net returns. There is a critical need to develop fully integrated management systems with supporting elements that accurately and inexpensively define dynamic management zones, sense within-field variability in real time, and then adaptively control site-specific variable rate water applications, which will be challenging as significant knowledge gaps exist

Nonenzymatic Glycosylation of Lepidopteran-Active \u3ci\u3eBacillus thuringiensis\u3c/i\u3e Protein Crystals

We used high-pH anion-exchange chromatography with pulsed amperometric detection to quantify the monosaccharides covalently attached to Bacillus thuringiensis HD-1 (Dipel) crystals. The crystals contained 0.54% sugars, including, in decreasing order of prevalence, glucose, fucose, arabinose/rhamnose, galactose, galactosamine, glucosamine, xylose, and mannose. Three lines of evidence indicated that these sugars arose from nonenzymatic glycosylation: (i) the sugars could not be removed by N- or O-glycanases; (ii) the sugars attached were influenced both by the medium in which the bacteria had been grown and by the time at which the crystals were harvested; and (iii) the chemical identity and stoichiometry of the sugars detected did not fit any known glycoprotein models. Thus, the sugars detected were the product of fermentation conditions rather than bacterial genetics. The implications of these findings are discussed in terms of crystal chemistry, fermentation technology, and the efficacy of B. thuringiensis as a microbial insecticide

Evaluation of Metals in a Defined Medium for \u3ci\u3ePichia pastoris\u3c/i\u3e Expressing Recombinant β-Galactosidase

Culture growth and recombinant protein yield of the Pichia pastoris GS115 methanol utilization positive system were studied in response to the types and levels of metals present in the growth medium and the supplemental salts typically used for these fermentations. Magnesium and zinc were both required to support cell growth but at significantly reduced levels compared to the control. However, supplementation with calcium, cobalt, iron, manganese, iodine, boron, and molybdenum were not required to sustain cell mass. When the medium was reformulated with only zinc and magnesium, the cells grew to 12–15 generations, which are expected for high cell density fed-batch fermentations. Product yields of the recombinant protein β-galactosidase were significantly influenced by the trace metal concentrations. By using response surface and full factorial designs, maximum protein yield occurred when the concentration of zinc salt was limited to the level necessary only to support cell mass while protein yield positively correlated to increasing levels of the remaining trace metal salts. These studies are the first to show that excess trace metals must be optimized when developing P. pastoris based fed-batch fermentations

Validation of Aircraft Noise Models at Lower Levels of Exposure

Noise levels around airports and airbases in the United States arc computed via the FAA's Integrated Noise Model (INM) or the Air Force's NOISEMAP (NMAP) program. These models were originally developed for use in the vicinity of airports, at distances which encompass a day night average sound level in decibels (Ldn) of 65 dB or higher. There is increasing interest in aircraft noise at larger distances from the airport. including en-route noise. To evaluate the applicability of INM and NMAP at larger distances, a measurement program was conducted at a major air carrier airport with monitoring sites located in areas exposed to an Ldn of 55 dB and higher. Automated Radar Terminal System (ARTS) radar tracking data were obtained to provide actual flight parameters and positive identification of aircraft. Flight operations were grouped according to aircraft type. stage length, straight versus curved flight tracks, and arrival versus departure. Sound exposure levels (SEL) were computed at monitoring locations, using the INM, and compared with measured values. While individual overflight SEL data was characterized by a high variance, analysis performed on an energy-averaging basis indicates that INM and similar models can be applied to regions exposed to an Ldn of 55 dB with no loss of reliability