Superb resolution and contrast of transmission electron microscopy images of unstained biological samples on graphene-coated grids

MED15 prion-like domain forms a coiled-coil responsible for its amyloid conversion and propagation

A disordered to β-sheet transition was thought to drive the functional switch of Q/N-rich prions, similar to pathogenic amyloids. However, recent evidence indicates a critical role for coiled-coil (CC) regions within yeast prion domains in amyloid formation. We show that many human prion-like domains (PrLDs) contain CC regions that overlap with polyQ tracts. Most of the proteins bearing these domains are transcriptional coactivators, including the Mediator complex subunit 15 (MED15) involved in bridging enhancers and promoters. We demonstrate that the human MED15-PrLD forms homodimers in solution sustained by CC interactions and that it is this CC fold that mediates the transition towards a β-sheet amyloid state, its chemical or genetic disruption abolishing aggregation. As in functional yeast prions, a GFP globular domain adjacent to MED15-PrLD retains its structural integrity in the amyloid state. Expression of MED15-PrLD in human cells promotes the formation of cytoplasmic and perinuclear inclusions, kidnapping endogenous full-length MED15 to these aggregates in a prion-like manner. The prion-like properties of MED15 are conserved, suggesting novel mechanisms for the function and malfunction of this transcription coactivator.

Applications of Graphene and Its Derivatives in Bone Repair: Advantages for Promoting Bone Formation and Providing Real-Time Detection, Challenges and Future Prospects

During continuous innovation in the preparation, characterization and application of various bone repair materials for several decades, nanomaterials have exhibited many unique advantages. As a kind of representative two-dimensional nanomaterials, graphene and its derivatives (GDs) such as graphene oxide and reduced graphene oxide have shown promising potential for the application in bone repair based on their excellent mechanical properties, electrical conductivity, large specific surface area (SSA) and atomic structure stability. Herein, we reviewed the updated application of them in bone repair in order to present, as comprehensively, as possible, their specific advantages, challenges and current solutions. Firstly, how their advantages have been utilized in bone repair materials with improved bone formation ability was discussed. Especially, the effects of further functionalization or modification were emphasized. Then, the signaling pathways involved in GDs-induced osteogenic differentiation of stem cells and immunomodulatory mechanism of GDs-induced bone regeneration were discussed. On the other hand, their applications as contrast agents in the field of bone repair were summarized. In addition, we also reviewed the progress and related principles of the effects of GDs parameters on cytotoxicity and residues. At last, the future research was prospected.

High-resolution analyses of the mineralisation process at bio/inorganic interfaces

To gain insight into bio-inspired mineralisation processes that may be directed or influenced by the protein coat of tobacco mosaic virus (TMV), microscopic studies are crucial. The authors elucidate key steps towards the understanding of the mineralisation mechanism by high-resolution transmission electron microscopy imaging of the organic/inorganic interfaces. Wild-type TMV and mutants with distinct surface properties are used to investigate the processes of nucleation and mineral formation based on ZnO and ZnS deposition. The development of suitable sample preparation methods is central in the study, as well as finding the optimal imaging conditions in combination with the use of a latest-generation high-end microscope. The mineralisation is to be analysed with respect to the underlying nucleation process: Correlation of structure findings with mechanical properties will pave the way to the goal of the design of materials with enhanced mechanical properties.

Prions

Infectious proteins (prions) are usually self-templating filamentous protein polymers (amyloids). Yeast prions are genes composed of protein and, like the multiple alleles of DNA-based genes, can have an array of "variants," each a distinct self-propagating amyloid conformation. Like the lethal mammalian prions and amyloid diseases, yeast prions may be lethal, or only mildly detrimental, and show an array of phenotypes depending on the protein involved and the prion variant. Yeast prions are models for both rare mammalian prion diseases and for several very common amyloidoses such as Alzheimer's disease, type 2 diabetes, and Parkinson's disease. Here, we describe their detection and characterization using genetic, cell biological, biochemical, and physical methods.

Herpes simplex virus type-1 attachment inhibition by functionalized graphene oxide

Graphene oxide and its derivatives have lately been the subject of increased attention in the field of bioscience and biotechnology. In this article, we report on the use of graphene oxide (GO) derivatives to inhibit herpes simplex virus type-1 (HSV-1) infections, mimicking the cell surface receptor heparan sulfate, and the GO derivatives compete with the latter in binding HSV-1. The inhibition does not affect cell-to-cell spreading. Media content has a significant effect on the inhibition properties of the nanomaterials. These have no cytotoxic effect, suggesting that this is a promising approach for the development of antiviral surfaces and for diagnostic purposes.