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SummaryGrass carp reovirus (GCRV) is a member of the Aquareovirus genus of the family Reoviridae, a large family of dsRNA viruses infecting plants, insects, fishes and mammals. We report the first subnanometer-resolution three-dimensional (3D) structures of both GCRV core and virion by cryoelectron microscopy (cryoEM). These structures have allowed the delineation of interactions among the over 1000 molecules in this enormous macromolecular machine, and a detail comparison with other dsRNA viruses at the secondary structure level. The GCRV core structure shows that the inner proteins have strong structural similarities even at the level of secondary structure elements with those of orthoreoviruses, indicating that the structures involved in viral dsRNA interaction and transcription are highly conserved. In contrast, the level of similarity in structures decreases in the proteins situated in the outer layers of the virion. The proteins involved in host recognition and attachment exhibit the least similarities to other members of Reoviridae. Furthermore, in GCRV, the RNA-translocating turrets are in an open state and lack a counterpart for the σ1 protein situated on top of the close turrets observed in mammalian orthoreovirus (MRV). Interestingly, the distribution and organization of GCRV core proteins resembles those of the cytoplasmic polyhedrosis virus (CPV), a cypovirus and the structurally simplest member of the Reoviridae family. Our results suggest that GCRV occupies a unique structure niche between the simpler cypoviruses and the considerably more complex MRV, thus providing an important model for understanding the structural and functional conservation and diversity of this enormous family of dsRNA viruses.

We report the recording and reconstruction of x-ray diffraction patterns from single, unstained viruses, for the first time. By separating the diffraction pattern of the virus particles from that of their surroundings, we performed quantitative and high-contrast imaging of a single virion. The structure of the viral capsid inside a virion was visualized. This work opens the door for quantitative x-ray imaging of a broad range of specimens from protein machineries and viruses to cellular organelles. Moreover, our experiment is directly transferable to the use of x-ray free electron lasers, and represents an experimental milestone towards the x-ray imaging of large protein complexes.

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Background:Titanium has been the most popular material of choice for dental implantology over the past few decades. Its properties have been found to be most suitable for the success of implant treatment. But recently, zirconia is slowly emerging as one of the materials which might replace the gold standard of dental implant, i.e., titanium.Materials and Methods:Literature was searched to retrieve information about zirconia dental implant and studies were critically analyzed. PubMed database was searched for information about zirconia dental implant regarding mechanical properties, osseointegration, surface roughness, biocompatibility, and soft tissue health around it. The literature search was limited to English language articles published from 1975 to 2015.Results:A total of 45 papers met the inclusion criteria for this review, among the relevant search in the database.Conclusion:Literature search showed that some of the properties of zirconia seem to be suitable for making it an ideal dental implant, such as biocompatibility, osseointegration, favourable soft tissue response and aesthetics due to light transmission and its color. At the same time, some studies also point out its drawbacks. It was also found that most of the studies on zirconia dental implants are short-term studies and there is a need for more long-term clinical trials to prove that zirconia is worth enough to replace titanium as a biomaterial in dental implantology.