Electron cryomicroscopy methods.

V M Unger

doi:10.1016/s0959-440x(00)00260-8

Home/Archive/PubMed

PubMed · 11785754

Electron cryomicroscopy methods.

V M Unger

View original source ↗Export metadata ↓

Abstract

Electron cryomicroscopy methods comprise a rapidly expanding field providing insights into the structure and function of biological macromolecules and their supramolecular assemblies. The 3.8 A resolution structure of the membrane protein aquaporin, a view of the herpesvirus capsid at 8.5 A and the 10 A resolution structure of the spliceosomal U1 small nuclear ribonucleoprotein complex are three outstanding examples emphasizing the versatility of this technique.

Explore related subjects

Aquaporins Capsid Cryoelectron Microscopy Crystallography Herpesviridae Image Processing, Computer-Assisted Macromolecular Substances Models, Molecular Protein Conformation Ribonucleoprotein, U1 Small Nuclear Solubility Tomography Journal Article Review

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

V M Unger. 2001. Electron cryomicroscopy methods.. https://doi.org/10.1016/s0959-440x(00)00260-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2003

Liquid-vapor oscillations of water in hydrophobic nanopores.

Water plays a key role in biological membrane transport. In ion channels and water-conducting pores (aquaporins), one-dimensional confinement in conjunction with strong surface effects changes the physical behavior of water. In molecular dynamics simulations of water in short (0.8 nm) hydrophobic pores the water density in the pore fluctuates on a nanosecond time scale. In long simulations (460 ns in total) at pore radii ranging from 0.35 to 1.0 nm we quantify the kinetics of oscillations between a liquid-filled and a vapor-filled pore. This behavior can be explained as capillary evaporation alternating with capillary condensation, driven by pressure fluctuations in the water outside the pore. The free-energy difference between the two states depends linearly on the radius. The free-energy landscape shows how a metastable liquid state gradually develops with increasing radius. For radii > approximately 0.55 nm it becomes the globally stable state and the vapor state vanishes. One-dimensional confinement affects the dynamic behavior of the water molecules and increases the self diffusion by a factor of 2-3 compared with bulk water. Permeabilities for the narrow pores are of the same order of magnitude as for biological water pores. Water flow is not continuous but occurs in bursts. Our results suggest that simulations aimed at collective phenomena such as hydrophobic effects may require simulation times >50 ns. For water in confined geometries, it is not possible to extrapolate from bulk or short time behavior to longer time scales.

Aquaporins↗

PubMed2003

The poplar root transcriptome: analysis of 7000 expressed sequence tags.

To date, most poplar expressed sequence tags (ESTs) are from above-ground tissues such as wood, leaf and buds. Here, we present a large-scale production of ESTs from roots of the hybrid cottonwood, Populus trichocarpaxdeltoides. cDNA libraries were generated from the root system of 2-month-old rooted cuttings, and roots of 2.5-month-old cuttings water-stressed for 19 days. Partial sequences obtained from 7013 clones were assembled into 1347 clusters and 3527 singletons. This set of ESTs represents 4874 unique transcripts expressed in roots. Putative functions could be assigned to 3021 (62%) of the transcripts. A significant portion of the ESTs encode proteins of common metabolic pathways; energy and metabolism represented 5% and 8% of total transcripts, respectively. Of specific interest to root functions are the 6% of ESTs involved in signalling pathways and hormone metabolism, and 4% encoding transporters and channels. The current poplar root ESTs and the aspen root ESTs present in public databases represent 6700 unique transcripts. The Unigene set was selected from the ESTs and used to generate nylon microarrays. Changes in aquaporins and transporter transcripts were then studied during adventitious root development.

Aquaporins↗

PubMed2003

Arbuscular mycorrhizal symbiosis and alleviation of osmotic stress. New perspectives for molecular studies.

Water deficit is considered one of the most important abiotic factors limiting plant growth and yield in many areas on earth. Several eco-physiological studies have demonstrated that the arbuscular mycorrhizal (AM) symbiosis often results in altered rates of water movement into, through and out of the host plants, with consequent effects on tissue hydration and plant physiology. It is now accepted that the contribution of AM symbiosis to plant drought tolerance is the result of accumulative physical, nutritional, physiological and cellular effects. This review considers several aspects that should be investigated at a molecular level in order to gain a whole understanding of the different mechanisms by which the AM symbiosis protects the host plants against the detrimental effects of water deficit.

Aquaporins↗