Identification of pathogenic Leptospira species by conventional or real-time PCR and sequencing of the DNA gyrase subunit B encoding gene

BACKGROUND: Leptospira is the causative genus of the disease, leptospirosis. Species identification of pathogenic Leptospira in the past was generally performed by either DNA-DNA hybridisation or 16s rRNA gene sequencing. Both methods have inherent disadvantages such as the need for radio-labelled isotopes or significant homology between species. A conventional and real-time PCR amplification and sequencing method was developed for an alternate gene target: DNA gyrase subunit B (gyrB). Phylogenetic comparisons were undertaken between pathogenic Leptospira 16srRNA and gyrB genes using clustering and minimum evolution analysis. In addition 50 unidentified Leptospira isolates were characterised by gyrB sequencing and compared with conventional 16s rRNA sequencing. RESULTS: A conventional and real-time PCR methodology was developed and optimised for the amplification of the gyrB from pathogenic Leptospira species. Non pathogenic and opportunistic Leptospira species such as L. fainei and L. broomi were not amplified. The gyrB gene shows greater nucleotide divergence (3.5% to 16.1%) than the 16s rRNA gene (0.1% to 1.4%). Minimum evolution analysis reveals that the gyrB has a different evolution topology for L. kirschneri and L. interrogans. When the two genes were compared for the identification of the 50 unknown isolates there was 100% agreement in the results. CONCLUSION: This research has successfully developed a methodology for the identification of pathogenic Leptospira using an alternate gene to 16s rRNA. The gyrB encoding gene shows higher nucleotide/evolutionary divergence allowing for superior identification and also the potential for the development of DNA probe based identification

Development of a Multiple-Locus Variable number of tandem repeat Analysis (MLVA) for Leptospira interrogans and its application to Leptospira interrogans serovar Australis isolates from Far North Queensland, Australia

BACKGROUND: Leptospirosis is a zoonotic disease caused by the genus, Leptospira. Leptospira interrogans is the most common genomospecies implicated in the disease. Epidemiological investigations are needed to distinguish outbreak situations or to trace reservoirs of the organisms. Current methodologies used for typing Leptospira have significant drawbacks. The development of an easy to perform yet high resolution method is needed for this organism. METHODS: In this study we have searched the available genomic sequence of L. interrogans serovar Copenhageni strain Fiocruz L1-130 for the presence of tandem repeats [1]. These repeats were evaluated against reference strains for diversity. Six loci were selected to create a Multiple Locus Variable Number of Tandem Repeats (VNTR) Analysis (MLVA) to explore the genetic diversity within L. interrogans serovar Australis clinical isolates from Far North Queensland. RESULTS: The 39 reference strains used for the development of the method displayed 39 distinct patterns. Diversity Indexes for the loci varied between 0.80 and 0.93 and the number of repeat units at each locus varied between less than one to 52 repeats. When the MLVA was applied to serovar Australis isolates three large clusters were distinguishable, each comprising various hosts including Rattus species, human and canines. CONCLUSION: The MLVA described in this report, was easy to perform, analyse and was reproducible. The loci selected had high diversity allowing discrimination between serovars and also between strains within a serovar. This method provides a starting point on which improvements to the method and comparisons to other techniques can be made

Cryptocurrency reaction to fomc announcements: Evidence of heterogeneity based on blockchain stack position

We examine the response of a broad set of digital assets to US Federal Fund interest rate and quantitative easing announcements, specifically examining associated volatility spillover and feedback effects. We classify each digital asset into one of three categories: Currencies; Protocols; and Decentralised Applications (dApps). Currency-based digital assets experience idiosyncratic spillovers in the period immediately after US monetary policy announcements, while application or protocol-based digital assets are largely immune to policy volatility spillover and feedback. Mineable digital assets are found to be more susceptible to monetary policy volatility spillovers and feedback than non-mineable. Responses indicate a diverse market within which, not all assets are comparable to Bitcoin

The influence of central bank monetary policy announcements on cryptocurrency return volatility

The emergence of Bitcoin in 2009 has received considerable attention surrounding the validity of cryptocurrencies as a viable and, in some jurisdictions, a legal currency alternative. Despite widespread concern that these cryptocurrencies are fostering the environment within which a substantial bubble can occur, it is important to analyze whether these new assets are behaving similarly to major international currencies. This paper investigates the effects of international monetary policy changes on bitcoin returns using a GARCH (1.1) estimation model. The results indicate that monetary policy decisions based on interest rates taken by the Federal Open Market Committee in the United States significantly impact upon bitcoin returns. After controlling for international effects, we find significant evidence of volatility effects driven by United States, European Union, United Kingdom and Japanese quantitative easing announcements. These results show that, despite its nature and ideals, bitcoin seems to be subject to the same economic factors as traditional fiat currencies, and is not entirely unaffected by government policies. This result has implications for investors using bitcoin as a hedging or diversification tool. In addition, we contribute to the existing debate regarding the classification of bitcoin as an asset class, by illustrating that bitcoin volatility exhibits various reactions that bear resemblance to both currency pairs and store-of-value assets

Cryptocurrency reaction to FOMC announcements: evidence of heterogeneity based on blockchain stack position

We examine the response of a broad set of digital assets to US Federal Fund interest rate and quantitative easing announcements, specifically examining associated volatility spillover and feedback effects. We classify each digital asset into one of three categories: Currencies; Protocols; and Decentralised Applications (dApps). Currency-based digital assets experience idiosyncratic spillovers in the period immediately after US monetary policy announcements, while application or protocolbased digital assets are largely immune to policy volatility spillover and feedback. Mineable digital assets are found to be more susceptible to monetary policy volatility spillovers and feedback than non-mineable. Responses indicate a diverse market within which, not all assets are comparable to Bitcoin

Does cryptocurrency pricing response to regulatory intervention depend on underlying blockchain architecture?

Blockchain technology appears to be ready to revolutionise a broad number of industries. However, the blockchain itself contains a number of inefficiencies and areas for improvement, namely: transaction fees and transaction speeds. Directed acyclic graphs (DAGs) address, and improve on these inefficiencies and a number of digital currencies utilising this technology have already begun to appear. This paper provides an explanation of the technology behind DAG-based assets, while identifying and highlighting strategic advantages that DAGs possess over traditional blockchains. We conduct an EGARCH volatility analysis of a range of blockchain-based and DAGbased cryptocurrencies in the aftermath of a range of market shocks, taking the form of regulatory announcements such as bans and broad restrictions for cryptocurrencies. We find that DAG-based assets become increasingly responsive to market shocks as they mature. Such behaviour mirrors that of established cryptocurrencies such as Bitcoin, Ethereum and Litecoin, providing evidence that DAG-based cryptocurrencies now share similar characteristics to traditional blockchain-chain based products

Optimisation of estrogen receptor subtype-selectivity of a 4-Aryl-4H-chromene scaffold previously identified by virtual screening

4-Aryl-4H-Chromene derivatives have been previously shown to exhibit anti-proliferative, apoptotic and anti-angiogenic activity in a variety of tumor models in vitro and in vivo generally via activation of caspases through inhibition of tubulin polymerisation. We have previously identified by Virtual Screening (VS) a 4-aryl-4H-chromene scaffold, of which two examples were shown to bind Estrogen Receptor α and β with low nanomolar affinity and \u3c20-fold selectivity for α over β and low micromolar anti-proliferative activity in the MCF-7 cell line. Thus, using the 4-aryl-4H-chromene scaffold as a starting point, a series of compounds with a range of basic arylethers at C-4 and modifications at the C3-ester substituent of the benzopyran ring were synthesised, producing some potent ER antagonists in the MCF-7 cell line which were highly selective for ERα (compound 35; 350-fold selectivity) or ERβ (compound 42; 170-fold selectivity)

The 3rd Fermi GBM Gamma-Ray Burst Catalog: The First Six Years

Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two gamma-ray bursts (GRB) every three days. Here we present the third of a series of catalogs of GRBs detected by GBM, extending the second catalog by two more years, through the middle of July 2014. The resulting list includes 1405 triggers identified as GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM detected GRBs. For each GRB the location and main characteristics of the prompt emission, the duration, peak flux and fluence are derived. The latter two quantities are calculated for the 50-300~keV energy band, where the maximum energy release of GRBs in the instrument reference system is observed, and also for a broader energy band from 10-1000 keV, exploiting the full energy range of GBM's low-energy NaI(Tl) detectors. Using statistical methods to assess clustering, we find that the hardness and duration of GRBs are better fitted by a two-component model with short-hard and long-soft bursts, than by a model with three components. Furthermore, information is provided on the settings and modifications of the triggering criteria and exceptional operational conditions during years five and six in the mission. This third catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).Comment: 225 pages, 13 figures and 8 tables. Accepted for publication in Astrophysical Journal Supplement 201

The GLAST Burst Monitor

The next large NASA mission in the field of gamma-ray astronomy, GLAST, is scheduled for launch in 2007. Aside from the main instrument LAT (Large-Area Telescope), a gamma-ray telescope for the energy range between 20 MeV and > 100 GeV, a secondary instrument, the GLAST burst monitor (GBM), is foreseen. With this monitor one of the key scientific objectives of the mission, the determination of the high-energy behaviour of gamma-ray bursts and transients can be ensured. Its task is to increase the detection rate of gamma-ray bursts for the LAT and to extend the energy range to lower energies (from ~10 keV to \~30 MeV). It will provide real-time burst locations over a wide FoV with sufficient accuracy to allow repointing the GLAST spacecraft. Time-resolved spectra of many bursts recorded with LAT and the burst monitor will allow the investigation of the relation between the keV and the MeV-GeV emission from GRBs over unprecedented seven decades of energy. This will help to advance our understanding of the mechanisms by which gamma-rays are generated in gamma-ray bursts.Comment: 8 pages, 7 figures, to appear in SPIE conference proceedings vol 5488, "UV-Gamma Ray Space Telescope Systems," Glasgow UK, 21-24 June 200