Here we report the discovery of two Tupanvirus strains, the longest tailed Mimiviridae members isolated in amoebae. Their genomes are 1.44–1.51 Mb linear double-strand DNA coding for 1276–1425 predicted proteins. Tupanviruses share the same ancestors with mimivirus lineages and these giant viruses present the largest translational apparatus within the known virosphere, with up to 70 tRNA, 20 aaRS, 11 factors for all translation steps, and factors related to tRNA/mRNA maturation and ribosome protein modification. Moreover, two sequences with significant similarity to intronic regions of 18 S rRNA genes are encoded by the tupanviruses and highly expressed. In this translation-associated gene set, only the ribosome is lacking. At high multiplicity of infections, tupanvirus is also cytotoxic and causes a severe shutdown of ribosomal RNA and a progressive degradation of the nucleus in host and non-host cells. The analysis of tupanviruses constitutes a new step toward understanding the evolution of giant viruses.
h i g h l i g h t sWe evaluate the effect of biodiesel on commercial rubber at molecular level. The new CMP-NMR probe was successful to study the phases in the fuel-rubber system. We observed that the biodiesel penetrates at EPDM despite the opposite report. It is observed the increasing on rubbers softening after biodiesel immersion. a b s t r a c t Biodiesel has been incorporated into the energy matrix in several countries, but its compatibility with some materials used in automotive engines is of growing concern. In the present study, comprehensive multiphase (CMP) NMR is applied to understand the different phases in fuel-rubber systems. CMP NMR is a novel technology that integrates all the hardware from solution-, gel-and solid-state into a single NMR probe, permitting all phases to be studied in samples in their natural unaltered state. Transverse relaxation experiments in combination with inverse diffusion editing permit the increasing mobility of the rubbers chains with biodiesel exposure to be monitored. Conversely diffusion editing and RADE experiments highlight the more rigid domains. In summary NR and NBR showed the absence of highly rigid domains after exposure to biodiesel whereas SBR and EPDM especially better retained their structural integrity. 13 C editing protocols and 13 C-1 H HSQC confirmed the increasing gel-like properties of NR, NBR and SBR with exposure to biodiesel. However, variable contact time experiments showed that biodiesel penetrates even the most resilient EPDM pores causing relaxation of the polymer chains and demonstrates that NMR is sensitive enough to highlight even the very slight swelling of the EPDM. Through these results it is possible to observe that the elastomer that exhibits the lowest susceptibility to biodiesel in molecular terms was EPDM, followed by SBR, NR, and NBR. It was also observed that biodiesel molecules were present in the EPDM structure despite the literature reporting its general resilience to biodiesel.
The discovery of giant viruses in the last years has fascinated the scientific community due to virus particles size and genome complexity. Among such fantastic discoveries, we have recently described tupanviruses, which particles present a long tail, and has a genome that contains the most complete set of translation-related genes ever reported in the known virosphere. Here we describe a new kind of virus-host interaction involving tupanvirus. We observed that tupanvirus-infected amoebas were induced to aggregate with uninfected cells, promoting viral dissemination and forming giant host cell bunches. Even after mechanical breakdown of bunches, amoebas reaggregated within a few minutes. This remarkable interaction between infected and uninfected cells seems to be promoted by the expression of a mannose receptor gene. Our investigations demonstrate that the pre-treatment of amoebas with free mannose inhibits the formation of bunches, in a concentration-dependent manner, suggesting that amoebal-bunch formation correlates with mannose receptor gene expression. Finally, our data suggest that bunch-forming cells are able to interact with uninfected cells promoting the dissemination and increase of tupanvirus progeny.
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