The development of azadirachtin as a soil-applied, granular insecticide

The aim of this project was to develop azadirachtin as an insecticide that is applied to the soil, using a granular formulation, for root uptake and subsequent systemic plant protection. A method was developed whereby azadirachtin could be rapidly isolated to approximately 95% purity using flash chromatography. This material was used in all subsequent chemical and biochemical studies. To increase the speed of crude extract analysis, a colorimetric technique was assessed to rapidly quantify azadirachtin. However, this method was generally unsuitable for the requirements of this project because it was non-specific and not stable. Granular formulations based on sodium alginate, starch-kaolin and poly(e-caprolactone), and containing different neem seed extracts were successfully prepared. These granules exhibited differnces in the rate of azadirachtin release into water. Additives such as kaolin clay and rapeseed oil could be used to modify the speed of release. Following application to soil, the position of granules did not affect release rates. However, granule application method was shown to affect the rate at which the limonoid was accumulated within the nasturtium plants. Azadirachtin was shown to be moderately water-soluble (1.29 g/l). During mixing studies between distilled water and n-octanol, the limonoid partitioned more favourably into the non-aqueous phase at a ratio of 7:1. Based on calculated Koc values (<40), azadirachtin was classified as very highly soil mobile. Adsorption occurred principally to the organic matter of soils. Clay minerals were comparably non-sorbent. Desorption from both of these sites occurred readily. Azadirachtin was not persistent within soil where the limonoid’s DT50 was as short as 1.06 days. Initial breakdown resulted in the acetyl moiety being cleaved from the molecule. In addition, azadirachtin was shown to exhibit a pH sensitive hydrolytic degradation. The limonoid’s half-life in solution ranged from 57 days at pH 5 to 7.15 hours at pH 9. In conclusion a suitable granule for a controlled-release of azadirachtin was developed

Spectroscopic characterization and detection of Ethyl Mercaptan in Orion

New laboratory data of ethyl mercaptan, CH$_{3}$CH$_{2}$SH, in the millimeter and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of $gauche$-CH$_3$CH$_2$SH towards Orion KL. 77 unblended or slightly blended lines plus no missing transitions in the range 80-280 GHz support this identification. A detection of methyl mercaptan, CH$_{3}$SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is $\simeq$ 5 times more abundant than ethyl mercaptan in the hot core of Orion KL.Comment: Accepted for publication in ApJL (30 January 2014)/ submitted (8 January 2014

Slot Machine Near Wins: Effects on Pause and Sensitivity to Win Ratios

When a near-win outcome occurs on a slot machine, stimuli presented resemble those presented when money is won, but no money is won. Research has shown that gamblers prefer and play for longer on slot machines that present near wins. One explanation for this is that near wins are conditioned reinforcers. If so, near wins would produce longer latencies to the next response than clear losses. Another explanation is that near wins produce frustration; if so, then near wins would produce shorter response latencies. The two current experiments manipulated win ratio across two concurrently available slot machines and also manipulated near win frequency. Latencies were longer following near wins, consistent with near wins functioning as conditioned reinforcers. We also explored the effects of near wins on sensitivity to relative win rate and found that higher rates of near wins were associated with greater sensitivity to relative win frequency, an effect also consistent with near wins as conditioned reinforcers

Host Subtraction, Filtering and Assembly Validations for Novel Viral Discovery Using Next Generation Sequencing Data.

The use of next generation sequencing (NGS) to identify novel viral sequences from eukaryotic tissue samples is challenging. Issues can include the low proportion and copy number of viral reads and the high number of contigs (post-assembly), making subsequent viral analysis difficult. Comparison of assembly algorithms with pre-assembly host-mapping subtraction using a short-read mapping tool, a k-mer frequency based filter and a low complexity filter, has been validated for viral discovery with Illumina data derived from naturally infected liver tissue and simulated data. Assembled contig numbers were significantly reduced (up to 99.97%) by the application of these pre-assembly filtering methods. This approach provides a validated method for maximizing viral contig size as well as reducing the total number of assembled contigs that require down-stream analysis as putative viral nucleic acids.This work was supported by Wellcome Trust WT091501MAThis is the author accepted manuscript. It is currently under an indefinite embargo pending publication by PLOS

Investigating the efficacy of a proposed marine protected area for the Endangered humphead wrasse Cheilinus undulatus at a remote island group in Seychelles

The humphead wrasse Cheilinus undulatus is an iconic, ecologically important and Endangered fish species associated with coral reefs in the Indo-Pacific region. Due to its large size and complex life history characteristics, it is vulnerable to overfishing and has undergone substantial population declines in parts of its range. Knowledge of the species’ movement ecology is currently limited to only 2 previous studies, and very little is known about populations in the western Indian Ocean. The present study aimed to use passive acoustic telemetry to investigate the importance of a remote coral reef to a population of humphead wrasse in the Republic of Seychelles, and subsequently assess the efficacy of a proposed marine protected area at this location for protection of the species. Tagged fish (n = 20) exhibited persistent (\u3e500 d) site fidelity, with low dispersal distances (mean ± SD: 6.44 ± 4.0 km) and restricted core activity spaces (50% Brownian bridge kernel utilization density: 0.91 ± 0.61 km2). Additionally, the study site was home to a group of large (total length 97.9 ± 20.6 cm) and currently unexploited humphead wrasse that showed long-term predictable site fidelity and thus could be vulnerable to over-exploitation. The establishment of a proposed no-take marine protected area at the study site would encompass the core home range area of all tagged humphead wrasse and could effectively conserve this stronghold of Endangered fish to ensure the persistence of the species in Seychelles waters

Metagenomic study of the viruses of African straw-coloured fruit bats: detection of a chiropteran poxvirus and isolation of a novel adenovirus

Viral emergence as a result of zoonotic transmission constitutes a continuous public health threat. Emerging viruses such as SARS coronavirus, hantaviruses and henipaviruses have wildlife reservoirs. Characterising the viruses of candidate reservoir species in geographical hot spots for viral emergence is a sensible approach to develop tools to predict, prevent, or contain emergence events. Here, we explore the viruses of Eidolon helvum, an Old World fruit bat species widely distributed in Africa that lives in close proximity to humans. We identified a great abundance and diversity of novel herpes and papillomaviruses, described the isolation of a novel adenovirus, and detected, for the first time, sequences of a chiropteran poxvirus closely related with Molluscum contagiosum. In sum, E. helvum display a wide variety of mammalian viruses, some of them genetically similar to known human pathogens, highlighting the possibility of zoonotic transmission