Search results for "elektronimikroskopia"

Cryo-EM structure of ssDNA bacteriophage ΦCjT23 provides insight into early virus evolution.

2022

AbstractThe origin of viruses remains an open question. While lack of detectable sequence similarity hampers the analysis of distantly related viruses, structural biology investigations of conserved capsid protein structures facilitate the study of distant evolutionary relationships. Here we characterize the lipid-containing ssDNA temperate bacteriophage ΦCjT23, which infects Flavobacterium sp. (Bacteroidetes). We report ΦCjT23-like sequences in the genome of strains belonging to several Flavobacterium species. The virion structure determined by cryogenic electron microscopy reveals similarities to members of the viral kingdom Bamfordvirae that currently consists solely of dsDNA viruses wit…

Effects of activated carbon ageing in three PCB contaminated sediments: Sorption efficiency and secondary effects on Lumbriculus variegatus.

2015

The sorption efficiency and possible secondary effects of activated carbon (AC) (o 63-200 μm) was studied with Lumbriculus variegatus in three PCB contaminated sediments applying long AC-sediment contact time (3 years). AC amendment efficiently reduced PCB bioavailability as determined with both, L. variegatus bioaccumulation test and passive samplers. However, dose related secondary effects of AC on egestion rate and biomass were observed (applied doses 0.25% and 2.5% sediment dry weight). The sorption capacity and secondary effects remained similar when the experiments were repeated after three years of AC-sediment contact time. Further, transmission electron microscopy (TEM) samples reve…

Structural mechanism of signal transduction in a phytochrome histidine kinase

2022

AbstractPhytochrome proteins detect red/far-red light to guide the growth, motion, development and reproduction in plants, fungi, and bacteria. Bacterial phytochromes commonly function as an entrance signal in two-component sensory systems. Despite the availability of three-dimensional structures of phytochromes and other two-component proteins, the conformational changes, which lead to activation of the protein, are not understood. We reveal cryo electron microscopy structures of the complete phytochrome from Deinoccocus radiodurans in its resting and photoactivated states at 3.6 Å and 3.5 Å resolution, respectively. Upon photoactivation, the photosensory core module hardly changes its ter…

Electron microscopy of gold nanoparticles at atomic resolution

2014

Detailed structure of a gold nanoparticle Adding only a few atoms or changing the capping ligand can dramatically change the structure of individual metal nanoparticles. Azubel et al. used aberration-corrected transmission electron microscopy to derive a three-dimensional reconstruction of water-soluble gold nanoparticles. Small-angle x-ray scattering and other techniques have also corroborated this model. They used this to determine the atomic structure, which compared favorably with density functional theory calculations, without assuming any a priori structural knowledge or the use of model fitting. Science , this issue p. 909

Characterization of spatial porosity and mineral distribution of crystalline rock using X-ray micro computed tomography, C-14-PMMA autoradiography an…

2019

The spatial porosity and mineral distribution of geological materials strongly affects transport processes in them. X-ray micro computed tomography (X-mu CT) has proven to be a powerful tool for characterizing the spatial mineral distribution of geological samples in 3-D. However, limitations in resolution prevent an accurate characterization of pore space especially for tight crystalline rock samples and 2-D methods such as C-14-polymethylmethacrylate (C-14-PMMA) autoradiography and scanning electron microscopy (SEM) are needed. The spatial porosity and mineral distributions of tight crystalline rock samples from Aspo, Sweden, and Olkiluoto, Finland, were studied here. The X-mu CT were use…

Algorithms and software for biological multiscale image analysis

2013

Development of novel probes for enterovirus B group to study uncoating and infection

2016

Enterovirus B group (EV-B) viruses are important human pathogens which cause a variety of diseases from mild respiratory illnesses to more severe acute infections such as myocarditis and meningitis. EV-Bs have also been associated with chronic infections and autoimmune diseases such as type I diabetes. Because of their significance, better and more accurate methods are necessary to track and visualize viruses in vitro and in vivo. This thesis focus on the development of novel probes to label viruses site-specifically and track infection in vitro. First, we established a covalent conjugation between gold nanocluster markers and EV-B viruses. We were able to visualize through electron microsc…

Nanomanipulaatioon ja elektronimikroskopiaan perustuva hiilinanoputkien käsittelymenetelmä

2008

Imaging connected porosity of crystalline rock by contrast agent-aided X-ray microtomography and scanning electron microscopy

2018

We set out to study connected porosity of crystalline rock using X‐ray microtomography and scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDS) with caesium chloride as a contrast agent. Caesium is an important radionuclide regarding the final deposition of nuclear waste and also forms dense phases that can be readily distinguished by X‐ray microtomography and SEM‐EDS. Six samples from two sites, Olkiluoto (Finland) and Grimsel (Switzerland), where transport properties of crystalline rock are being studied in situ, were investigated using X‐ray microtomography and SEM‐EDS. The samples were imaged with X‐ray microtomography, immersed in a saturated caesium chlorid…

Chemically Selective Imaging of Individual Bonds through Scanning Electron Energy-Loss Spectroscopy : Disulfide Bridges Linking Gold Nanoclusters

2020

As proof-of-principle of chemically selective, spatially resolved imaging of individual bonds, we carry out electron energy-loss spectroscopy in a scanning transmission electron microscopy instrument on atomically precise, thiolate-coated gold nanoclusters linked with 5,5′-bis(mercaptomethyl)-2,2′-bipyridine dithiol ligands. The images allow the identification of bridging disulfide bonds (R–S–S–R) between clusters, and X-ray photoelectron spectra support the finding. peerReviewed