Abstract Objective/background Mycobacterium africanum (MAF) remains an important TB causing pathogen in West Africa; however, little is known about its population structure and actual diversity which ...may have implications for diagnostics and vaccines. We carried out comparative genomics analysis of candidate Mycobacterium tuberculosis (MTB) and MAF using whole genome sequencing. Methods Clinical MTB complex strains ( n = 187) comprising L4 ( n = 22), L5 ( n = 126), and L6 ( n = 39) isolated over 8 years from Ghana were whole genome sequenced. The reads were mapped onto a reference genome for phylogenetic and functional genomics analysis. A maximum likelihood tree with 100 bootstraps was constructed from the single nucleotide polymorphisms (SNPs) found using RAxML and clustered with hierBAPS. A total of 147 (18 L4, 36 L6, and 93 L5) of the genomes were de novo assembled and annotated for comparative pangenome analysis using Roary. Results The population structure of MAF revealed at least five clusters of L5 as compared to three for L6. We also identified a group of three multi-drug-resistants (MDRs) within a single cluster of L5 strains from Southern Ghana isolated in 2013. Among the global collection of MTB complex, there were four Ghana-specific L5 clusters of which one (L5.1.1) had traits of clonal expansion. From the 5947 pan genes extracted from the collection, 3215 (54.1%) were core to all the 147 genomes whereas 719 (12.1%) were found in single genomes. Most of the variable genes were PE-PGRS/PPE (1,281) duplicates of other genes (431). The genome degradation was more pronounced in Lineages 4 and 6 as compared to Lineage 5. We identified the absence of some unique genes among specific lineages and/or clades with possible clinical implications. For example, mpt64 and mlaD encoding respectively an immunogenic protein and a mammalian cell entry protein were missing from all L6 genomes. In addition, all L5 strains had an amino acid substitution I43 N within the mpt64 gene. Analysis of SNPs within some genes encoding proteins for substrate metabolism, ion transport and secretory systems showed higher proportion of SNPs among L6 compared to L5 and L4. We also identified a number of lineage/sublineage specific SNPs and indels that may be utilized in rapid PCR based genotyping of MTB complex. Conclusion This work emphasizes on the possibility that the mpt64 -based rapid diagnostic kit would not be effective in MAF endemic settings. More mutations in ESAT-6 secretory system of MAF compared to MTB sensu stricto can affect efficacy of ESAT-6-based vaccines in the future.
The decay of Λ-hypernuclei without π emission, known as Non-Mesonic Weak Decay (NMWD), gives an effective tool to investigate ΔS=1 four-baryon interactions. It was theoretically suggested that the ...two-nucleon induced mechanism could play a substantial role in reproducing the observed NMWD decay rates and nucleon spectra, but at present no direct evidence of such a mechanism has been obtained. The FINUDA experiment, exploiting the possibility to detect both charged and neutral particles coming from the hypernucleus decay, has allowed us to deduce the relative weight of the two nucleon induced decay rate to the total NMWD rate. The value of Γ2N/ΓNMWD=0.21±0.07stat−0.02sys+0.03sys has been deduced, well consistent with the previous determinations.
This Letter is concerned with the study of the Kstop−A→π±Σ∓A′ reaction in p-shell nuclei, i.e., 6,7Li, 9Be, 13C and 16O. The π±Σ∓/Kstop− emission rates are reported as a function of A. These rates ...are discussed in comparison with previous findings. The ratio π−Σ+/π+Σ− in p-shell nuclei is found to depart largely from that on hydrogen, which provides support for large in-medium effects possibly generated by the sub-threshold Λ(1405). The continuum momentum spectra of prompt pions and free sigmas are also discussed as well as the π±Σ∓ missing mass behavior and the link with the reaction mechanism. The apparatus used for the investigation is the FINUDA spectrometer operating at the DAΦNEϕ-factory (LNF-INFN, Italy).
On the muon neutrino mass Angelov, N.; Balestra, F.; Batusov, Yu ...
Nuclear physics. A,
12/2006, Letnik:
780, Številka:
1
Journal Article
Recenzirano
During the runs of the PS 179 experiment at LEAR of CERN, we photographed an event of antiproton–Ne absorption, with a complete
π
+
→
μ
+
→
e
+
chain. From the vertex of the reaction a very slow ...energy
π
+
was emitted. The
π
+
decays into a
μ
+
and subsequently the
μ
+
decays into a positron. At the first decay vertex a muon neutrino was emitted and at the second decay vertex an electron neutrino and a muon antineutrino. Measuring the pion and muon tracks and applying the momentum and energy conservation and using a classical statistical interval estimator, we obtained an experimental upper limit for the muon neutrino mass:
m
ν
<
2.2
MeV
at a 90% confidence level. A statistical analysis has been performed of the factors contributing to the square value of the neutrino mass, to deduce the possibility to reach experimentally the lowest muon neutrino mass limit from the
π
→
μ
ν
decays.
The J-PARC E15 experiment searches for the simplest kaonic nuclear bound state, K−pp, via the 3He(K−,n) reaction at the K1.8BR beam-line in the J-PARC hadron experimental facility. We performed the ...first data-taking in May, 2013, with 5 × 109 incident kaons on the 3He target. The preliminary results are reported focusing on the forward-neutron spectrum, which shows a clear peak structure composed of the quasi-elastic K−"n" → K−n and the charge-exchange K−"p" → 0n reactions as expected.
The FINUDA experiment collected data to study the production of hypernuclei on different nuclear targets. The hypernucleus formation occurred through the strangeness-exchange reaction ...Kstop−+ZA→ZΛA+π−. From the analysis of the momentum of the emerging π−, binding energies and formation probabilities of LiΛ7, BeΛ9, CΛ13 and OΛ16 have been measured and are here presented. The behavior of the formation probability as a function of the atomic mass number A is also discussed.
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