Expression of the Periplaneta americana\u27s α-adrenergic-like octopamine receptor in the yeast Saccharomyces cerevisiae: A high-throughput screening system in search of biorational insecticides

The use of conventional synthetic insecticides is facing increased scrutiny due to environmental and mammalian health concerns along with resistance to target insects. This has led to an investigation of alternative control measures to combat both economically and medically important arthropods. Octopamine, a biogenic amine, has significant physiological functions in invertebrates, including insects, and signals through G-protein-coupled receptors (GPCRs). Co-evolution of plants with insects has led to plants adapting defensive mechanisms to deter herbivore, microbial, or viral attack. This is sometimes accomplished via the production of essential oils that are composed of a variety of compounds, in particular monoterpenoids, sesquiterpenoids and aromatic compounds. Here we report on the functional coupling of a ligand-independent α-adrenergic-like octopamine receptor from the American cockroach and its expression in the yeast, Saccharomyces cerevisiae. This expression system allows us to screen a large number of compounds to determine efficacy at this octopamine receptor. We have found many monoterpenoids, sesquiterpenoids and aromatic compounds from essential oils that interact with this octopamine receptor and may account for their insecticidal action in this insect

Handshaking Protocols and Jamming Mechanisms for Blind Rendezvous in a Dynamic Spectrum Access Environment

Blind frequency rendezvous is an important process for bootstrapping communications between radios without the use of pre-existing infrastructure or common control channel in a Dynamic Spectrum Access (DSA) environment. In this process, radios attempt to arrive in the same frequency channel and recognize each other’s presence in changing, under-utilized spectrum. This paper refines existing blind rendezvous techniques by introducing a handshaking algorithm for setting up communications once two radios have arrived in the same frequency channel. It then investigates the effect of different jamming techniques on blind rendezvous algorithms that utilize this handshake. The handshake performance is measured by determining the probability of a handshake, the time to handshake, and the increase in time to rendezvous (TTR) with a handshake compared to that without. The handshake caused varying increases in TTR depending on the time spent in each channel. Four different jamming techniques are applied to the blind rendezvous process: noise, deceptive, sense, and Primary User Emulation (PUE). Each jammer type is analyzed to determine how they increase the TTR, how often they successfully jam over a period of time, and how long it takes to jam. The sense jammer was most effective, followed by PUE, deceptive, and noise, respectively

Constructing an External Cavity Diode Laser for the Probing of Rydberg Excitons in Cu2O

Cuprous oxide (Cu2O) is a direct bandgap semiconductor that presents a promising platform for the implementation of a solid state quantum simulator. This promise is in part due to the presence of excitons in the material which have the potential to become excited to Rydberg states, which are robust even in the presence of liquid nitrogen temperature thermal environments. The properties of the Rydberg excitons in Cu2O can be studied by the proxy of a series of P-exciton resonance peaks. For the study of peaks corresponding to principle quantum number n > 12 in the yellow P-series, high resolution spectroscopy methods are required due to the n^(-3) scaling of the width of each resonant peak. However, a tunable narrow linewidth light source, such as an external cavity diode laser, can be used to resolve these states by scanning the wavelength of the laser and measuring its transmission through a sample. Such a laser source can also be used in further experiments to probe and manipulate the excitonic state of the material, by for example inducing a Rydberg blockade. A narrow line-width tunable laser system capable of generating the required wavelengths of light via cavity enhanced second harmonic generation to scan the yellow P-exciton spectrum is constructed, and a high resolution transmission scan is performed. The results of the scan show close agreement with previously and concurrently obtained white light transmission spectroscopy results. This close agreement is somewhat corroborated by further qualitative analysis performed by fitting an asymmetric Lorentzian function to visible exciton resonance spectral features, and comparing the extracted values of the function parameters between the white light and laser light data

Botanical pesticides: identification of a molecular target and mode of action studies

Mosquitoes and ticks are vectors of several diseases that affect both humans and animals. Control of mosquito-borne and tick-borne diseases has primarily been achieved with the use of chemical insecticides/acaricides. However, an increase in public concern about the safety of conventional synthetic compounds, along with growing insecticide/acaricide resistance, has resulted in a need to find alternatives to control ticks and mosquitoes. In this dissertation I report on the functional and pharmacological characterization of a tyramine receptor from the southern cattle tick (Rhipicephalus microplus). Additionally, I report on the role of botanical essential oil terpenoids to interact with the southern cattle tick\u27s tyramine receptor. Physiological studies of the southern cattle tick\u27s tyramine receptor, using post-transcription gene silencing, show that the southern cattle tick\u27s tyramine receptor is a target that can result in tick mortality. The significance of these results is the reclassification of the southern cattle tick\u27s tyramine receptor (previously thought to be an octopamine receptor), the identification of a potentially novel target of plant terpenoids in the southern cattle tick and an explanation for the potential role of formamidine resistance, which has been reported in the southern cattle tick. Finally, I present the ability of essential oils to enhance the toxicity and/or knockdown of the synthetic pyrethroid permethrin, against two mosquito species (Aedes aegypti and Anopheles gambiae). The enhancement of toxicity and knockdown is similar to, but in many cases, better than the commercial synergist piperonyl butoxide (PBO). The significance of these findings includes the ability to use natural control measures to replace PBO, which has been under scrutiny for non-target toxicological issues

Biopesticides: State of the Art and Future Opportunities

The use of biopesticides and related alternative management products is increasing. New tools, including semiochemicals and plant-incorporated protectants (PIPs), as well as botanical and microbially derived chemicals, are playing an increasing role in pest management, along with plant and animal genetics, biological control, cultural methods, and newer synthetics. The goal of this Perspective is to highlight promising new biopesticide research and development (R&D), based upon recently published work and that presented in the American Chemical Society (ACS) symposium “Biopesticides: State of the Art and Future Opportunities,” as well as the authors’ own perspectives. Although the focus is on biopesticides, included in this Perspective is progress with products exhibiting similar characteristics, namely those naturally occurring or derived from natural products. These are target specific, of low toxicity to nontarget organisms, reduced in persistence in the environment, and potentially usable in organic agriculture. Progress is being made, illustrated by the number of biopesticides and related products in the registration pipeline, yet major commercial opportunities exist for new bioherbicides and bionematicides, in part occasioned by the emergence of weeds resistant to glyphosate and the phase-out of methyl bromide. The emergence of entrepreneurial start-up companies, the U.S. Environmental Protection Agency (EPA) fast track for biopesticides, and the availability of funding for registration-related R&D for biorational pesticides through the U.S. IR-4 program provide incentives for biopesticide development, but an expanded effort is warranted both in the United States and worldwide to support this relatively nascent industry

Covariant equations for the three-body bound state

The covariant spectator (or Gross) equations for the bound state of three identical spin 1/2 particles, in which two of the three interacting particles are always on shell, are developed and reduced to a form suitable for numerical solution. The equations are first written in operator form and compared to the Bethe-Salpeter equation, then expanded into plane wave momentum states, and finally expanded into partial waves using the three-body helicity formalism first introduced by Wick. In order to solve the equations, the two-body scattering amplitudes must be boosted from the overall three-body rest frame to their individual two-body rest frames, and all effects which arise from these boosts, including the Wigner rotations and rho-spin decomposition of the off-shell particle, are treated exactly. In their final form, the equations reduce to a coupled set of Faddeev-like double integral equations with additional channels arising from the negative rho-spin states of the off-shell particle.Comment: 57 pages, RevTeX, 6 figures, uses epsf.st

Comparison of the Insecticidal Characteristics of Commercially Available Plant Essential Oils Against Aedes aegypti and Anopheles gambiae (Diptera: Culicidae)

Aedes aegypti and Anopheles gambiae are two mosquito species that represent significant threats to global public health as vectors of Dengue virus and malaria parasites, respectively. Although mosquito populations have been effectively controlled through the use of synthetic insecticides, the emergence of widespread insecticide-resistance in wild mosquito populations is a strong motivation to explore new insecticidal chemistries. For these studies, Ae. aegypti and An. gambiae were treated with commercially available plant essential oils via topical application. The relative toxicity of each essential oil was determined, as measured by the 24-h LD50 and percentage knockdown at 1 h, as compared with a variety of synthetic pyrethroids. For Ae. aegypti, the most toxic essential oil (patchouli oil) was ∼1,700-times less toxic than the least toxic synthetic pyrethroid, bifenthrin. For An. gambiae, the most toxic essential oil (patchouli oil) was ∼685-times less toxic than the least toxic synthetic pyrethroid. A wide variety of toxicities were observed among the essential oils screened. Also, plant essential oils were analyzed via gas chromatography/mass spectrometry (GC/MS) to identify the major components in each of the samples screened in this study. While the toxicities of these plant essential oils were demonstrated to be lower than those of the synthetic pyrethroids tested, the large amount of GC/MS data and bioactivity data for each essential oil presented in this study will serve as a valuable resource for future studies exploring the insecticidal quality of plant essential oils

Long-acting beta(2)-agonist in addition to tiotropium versus either tiotropium or long-acting beta(2)-agonist alone for chronic obstructive pulmonary disease

BackgroundLong-acting bronchodilators comprising long-acting beta(2)-agonists and the anticholinergic agent tiotropium are commonly used for managing persistent symptoms of chronic obstructive pulmonary disease. Combining these treatments, which have different mechanisms of action, may be more effective than the individual components. However, the benefits and risks of combining tiotropium and long-acting beta2-agonists for the treatment of chronic obstructive pulmonary (COPD) disease are unclear.ObjectivesTo assess the relative effects of treatment with tiotropium in addition to long-acting beta(2)-agonist compared to tiotropium or long-acting beta2-agonist alone in patients with chronic obstructive pulmonary disease.Search methodsWe searched the Cochrane Airways Group Specialised Register of trials and clinicaltrials.gov up to January 2012.Selection criteriaWe included parallel group, randomised controlled trials of three months or longer comparing treatment with tiotropium in addition to long-acting beta2-agonist against tiotropium or long-acting beta2-agonist alone for patients with chronic obstructive pulmonary disease.Data collection and analysisTwo review authors independently assessed trials for inclusion and then extracted data on trial quality and the outcome results. We contacted study authors for additional information. We collected information on adverse effects from the trials.Main resultsFive trials were included in this review, mostly recruiting participants with moderate or severe chronic obstructive pulmonary disease. All of them compared tiotropium in addition to long-acting beta(2)-agonist to tiotropium alone, but only one trial additionally compared a combination of the two types of bronchodilator with long-acting beta2-agonist (formoterol) alone. Two studies used the long-acting beta2-agonist indacaterol, two used formoterol and one used salmeterol.Compared to tiotropium alone (3263 patients), treatment with tiotropium plus long-acting beta2-agonist resulted in a slightly larger improvement in the mean health-related quality of life (St George's Respiratory Questionnaire (SGRQ) MD -1.61; 95% CI -2.93 to -0.29). In the control arm, tiotropium alone, the SGRQ improved by falling 4.5 units from baseline and with both treatments the improvement was a fall of 6.1 units from baseline (on average). High withdrawal rates in the trials increased the uncertainty in this result, and the GRADE assessment for this outcome was therefore moderate. There were no significant differences in the other primary outcomes (hospital admission or mortality).The secondary outcome of pre-bronchodilator FEV1 showed a small mean increase with the addition of long-acting beta2-agonist (MD 0.07 L; 95% CI 0.05 to 0.09) over the control arm, which showed a change from baseline ranging from 0.03 L to 0.13 L on tiotropium alone. None of the other secondary outcomes (exacerbations, symptom scores, serious adverse events, and withdrawals) showed any statistically significant differences between the groups. There were wide confidence intervals around these outcomes and moderate heterogeneity for both exacerbations and withdrawals.The results from the one trial comparing the combination of tiotropium and long-acting beta2-agonist to long-acting beta2-agonist alone (417 participants) were insufficient to draw firm conclusions for this comparison.Authors' conclusionsThe results from this review indicate a small mean improvement in health-related quality of life for patients on a combination of tiotropium and long-acting beta2-agonist compared to tiotropium alone, but it is not clear how clinically important this mean difference may be. Hospital admission and mortality have not been shown to be altered by adding long-acting beta(2)-agonists to tiotropium. There were not enough data to determine the relative efficacy and safety of tiotropium plus long-acting beta2-agonist compared to long-acting beta2-agonist alone. There were insufficient data to make comparisons between the different long-acting beta2-agonists when used in addition to tiotropium

Dynamical coupled-channel model of meson production reactions in the nucleon resonance region

A dynamical coupled-channel model is presented for investigating the nucleon resonances in the meson production reactions induced by pions and photons. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method. By applying the projection operator techniques,we derive a set of coupled-channel equations which satisfy the unitarity conditions within the channel space spanned by the considered two-particle meson-baryon states and the three-particle $\pi\pi N$ state. We present and explain in detail a numerical method based on a spline-function expansion for solving the resulting coupled-channel equations which contain logarithmically divergent one-particle-exchange driving terms resulted from the $\pi\pi N$ unitarity cut. We show that this driving term can generate rapidly varying structure in the reaction amplitudes associated with the unstable particle channels. It also has large effects in determining the two-pion production cross sections. Our results indicate that cautions must be taken to interpret the $N^*$ parameters extracted from using models which do not include $\pi\pi N$ cut effects.Comment: 73 pages, 20 figure