Sigma viruses from three species of Drosophila form a major new clade in the rhabdovirus phylogeny

The sigma virus (DMelSV), which is a natural pathogen of Drosophila melanogaster, is the only Drosophila-specific rhabdovirus that has been described. We have discovered two new rhabdoviruses, D. obscura and D. affinis, which we have named DObsSV and DAffSV, respectively. We sequenced the complete genomes of DObsSV and DMelSV, and the L gene from DAffSV. Combining these data with sequences from a wide range of other rhabdoviruses, we found that the three sigma viruses form a distinct clade which is a sister group to the Dimarhabdovirus supergroup, and the high levels of divergence between these viruses suggest that they deserve to be recognized as a new genus. Furthermore, our analysis produced the most robustly supported phylogeny of the Rhabdoviridae to date, allowing us to reconstruct the major transitions that have occurred during the evolution of the family. Our data suggest that the bias towards research into plants and vertebrates means that much of the diversity of rhabdoviruses has been missed, and rhabdoviruses may be common pathogens of insects

Host Phylogeny Determines Viral Persistence and Replication in Novel Hosts

Pathogens switching to new hosts can result in the emergence of new infectious diseases, and determining which species are likely to be sources of such host shifts is essential to understanding disease threats to both humans and wildlife. However, the factors that determine whether a pathogen can infect a novel host are poorly understood. We have examined the ability of three host-specific RNA-viruses (Drosophila sigma viruses from the family Rhabdoviridae) to persist and replicate in 51 different species of Drosophilidae. Using a novel analytical approach we found that the host phylogeny could explain most of the variation in viral replication and persistence between different host species. This effect is partly driven by viruses reaching a higher titre in those novel hosts most closely related to the original host. However, there is also a strong effect of host phylogeny that is independent of the distance from the original host, with viral titres being similar in groups of related hosts. Most of this effect could be explained by variation in general susceptibility to all three sigma viruses, as there is a strong phylogenetic correlation in the titres of the three viruses. These results suggest that the source of new emerging diseases may often be predictable from the host phylogeny, but that the effect may be more complex than simply causing most host shifts to occur between closely related hosts

Iron alloys with new functional properties obtained during reverse martensitic transformation

It was shown that different types of the austenite (homogeneous and inhomogeneous polyhedral, or submicrocrystalline and nanocrystalline plate austenite) can be formed, providing new functional properties of various steels and alloys. The austenite formed during a partial $\alpha\to\gamma$ transformation increases considerably the strength of the martensite, enhances the coercive force and improves the square shape of the hysteresis loop of maraging steels. The thermal expansion coefficient of the austenitic alloy type 32Ni can be adjusted over broad limits thanks to different $\alpha\to\gamma$ transformation conditions. A stainless steel with a structure of alternating laths of the martensite and the austenite has a high resistance to radiation void formation

Hydrogen-induced reduction of electric field gradient in La(2)Fe(14)BHx studied by NMR on (139)LA

The La-139 NMR spin-echo spectra of La2Fe14BHx are reported. Since lanthanum has no 4f electrons, the observed quadrupole splittings are directly proportional to the lattice part of the electric field gradient, V-zz(lat). This quantity decreases as the content of interstitial hydrogen x grows. To describe the fall-off of V-zz(lat), a dimensionless function f(2)(x) is introduced, normalised so that f(2)(0) = 1. Analysis of the new and earlier published data obtained by several experimental techniques demonstrates that the reduction of both the second-order crystal field parameter AN and the lattice electric field gradient V-zz(lat) is described by the same function f(2)(x) in all R2Fe14BHx. The only distinction that needs to be made is between R being a light and a heavy rare earth. (C) 2003 Elsevier Ltd. All rights reserved.</p

Hydrogen-induced reduction of electric field gradient in La(2)Fe(14)BHx studied by NMR on (139)LA

The La-139 NMR spin-echo spectra of La2Fe14BHx are reported. Since lanthanum has no 4f electrons, the observed quadrupole splittings are directly proportional to the lattice part of the electric field gradient, V-zz(lat). This quantity decreases as the content of interstitial hydrogen x grows. To describe the fall-off of V-zz(lat), a dimensionless function f(2)(x) is introduced, normalised so that f(2)(0) = 1. Analysis of the new and earlier published data obtained by several experimental techniques demonstrates that the reduction of both the second-order crystal field parameter AN and the lattice electric field gradient V-zz(lat) is described by the same function f(2)(x) in all R2Fe14BHx. The only distinction that needs to be made is between R being a light and a heavy rare earth. (C) 2003 Elsevier Ltd. All rights reserved.</p