A joint theoretical/experimental study of the structure, dynamics, and Li+ transport in bis([tri]fluoro[methane]sulfonyl)imide [T]FSI-based ionic liquids.

The structure and dynamics of N-butyl-N-methyl pyrrolidinium(+) bis([tri]fluoro[methane]sulfonyl)imide(-) (PYR14(+)-[T]FSI(-)) ionic liquids doped with Li(T)FSI are investigated by combining experimental measurements to molecular dynamics simulations. The polarizable force field calculations indicate that the lithium cations are coordinated by (T)FSI anion oxygens forming lithium adducts stabilized over a large temperature range by strong Li-O bonds. Lithium aggregation is found to be negligible at the doping level considered here (10% mole fraction), and Li(+) diffusion occurs primarily by exchanging the (T)FSI anions in their first coordination shell. The resulting calculated transport properties are in good agreement with the corresponding nuclear magnetic resonance data.

Characterization of a Xenopus tropicalis endogenous retrovirus with developmental and stress-dependent expression.

We report on the identification and characterization of XTERV1, a full-length endogenous retrovirus (ERV) within the genome of the western clawed frog (Xenopus tropicalis). XTERV1 contains all the basic genetic elements common to ERVs, including the classical 5'-long terminal repeat (LTR)-gag-pol-env-3'-LTR architecture, as well as conserved functional motifs inherent to each retroviral protein. Using phylogenetic analysis, we show that XTERV1 is related to the Epsilonretrovirus genus. The X. tropicalis genome harbors a single full-length copy with intact gag and pol open reading frames that localizes to the centromeric region of chromosome 5. About 10 full-length defective copies of XTERV1 are found interspersed in the genome, and 2 of them could be assigned to chromosomes 1 and 3. We find that XTERV1 genes are zygotically transcribed in a regulated spatiotemporal manner during frog development, including metamorphosis. Moreover, XTERV1 transcription is upregulated under certain cellular stress conditions, including cytotoxic and metabolic stresses. Interestingly, XTERV1 Env is found to be homologous to FR47, a protein upregulated following cold exposure in the freeze-tolerant wood frog (Rana sylvatica). In addition, we find that R. sylvatica FR47 mRNA originated from a retroviral element. We discuss the potential role(s) of ERVs in physiological processes in vertebrates.