Gold nanoparticles induce nuclear damage in breast cancer cells,which is further amplified by hyperthermia

Gold nanoparticles have emerged as promising tools for cancer research and therapy, where they can promote thermal killing. The molecular mechanisms underlying these events are not fully understood. The geometry and size of gold nanoparticles can determine the severity of cellular damage. Therefore, small and big gold nanospheres as well as gold nanoflowers were evaluated side-by-side. To obtain quantitative data at the subcellular and molecular level, we assessed how gold nanoparticles, either alone or in combination with mild hyperthermia, altered the physiology of cultured human breast cancer cells. Our analyses focused on the nucleus, because this organelle is essential for cell survival. We showed that all the examined gold nanoparticles associated with nuclei. However, their biological effects were quantitatively different. Thus, depending on the shape and size, gold nanoparticles changed multiple nuclear parameters. They redistributed stress-sensitive regulators of nuclear biology, altered the nuclear morphology, reorganized nuclear laminae and envelopes, and inhibited nucleolar functions. In particular, gold nanoparticles reduced the de novo biosynthesis of RNA in nucleoli, the subnuclear compartments that produce ribosomes. While small gold nanospheres and nanoflowers, but not big gold nanospheres, damaged the nucleus at normal growth temperature, several of these defects were further exacerbated by mild hyperthermia. Taken together, the toxicity of gold nanoparticles correlated with changes in nuclear organization and function. These results emphasize that the cell nucleus is a prominent target for gold nanoparticles of different morphologies. Moreover, we demonstrated that RNA synthesis in nucleoli provides quantitative information on nuclear damage and cancer cell survival.     

From protein sequences to 3D-structures and beyond: the example of the UniProt Knowledgebase

With the dramatic increase in the volume of experimental results in every domain of life sciences, assembling pertinent data and combining information from different fields has become a challenge. Information is dispersed over numerous specialized databases and is presented in many different formats. Rapid access to experiment-based information about well-characterized proteins helps predict the function of uncharacterized proteins identified by large-scale sequencing. In this context, universal knowledgebases play essential roles in providing access to data from complementary types of experiments and serving as hubs with cross-references to many specialized databases. This review outlines how the value of experimental data is optimized by combining high-quality protein sequences with complementary experimental results, including information derived from protein 3D-structures, using as an example the UniProt knowledgebase (UniProtKB) and the tools and links provided on its website (). It also evokes precautions that are necessary for successful predictions and extrapolations.     

The transmembrane protein meckelin (MKS3) is mutated in Meckel-Gruber syndrome and the wpk rat

Meckel-Gruber syndrome is a severe autosomal, recessively inherited disorder characterized by bilateral renal cystic dysplasia, developmental defects of the central nervous system (most commonly occipital encephalocele), hepatic ductal dysplasia and cysts and polydactyly. MKS is genetically heterogeneous, with three loci mapped: MKS1, 17q21-24 (ref. 4); MKS2, 11q13 (ref. 5) and MKS3 (ref. 6). We have refined MKS3 mapping to a 12.67-Mb interval (8q21.13-q22.1) that is syntenic to the Wpk locus in rat, which is a model with polycystic kidney disease, agenesis of the corpus callosum and hydrocephalus. Positional cloning of the Wpk gene suggested a MKS3 candidate gene, TMEM67, for which we identified pathogenic mutations for five MKS3-linked consanguineous families. MKS3 is a previously uncharacterized, evolutionarily conserved gene that is expressed at moderate levels in fetal brain, liver and kidney but has widespread, low levels of expression. It encodes a 995-amino acid seven-transmembrane receptor protein of unknown function that we have called meckelin.     

Single mimivirus particles intercepted and imaged with an X-ray laser

X-ray lasers offer new capabilities in understanding the structure of biological systems, complex materials and matter under extreme conditions. Very short and extremely bright, coherent X-ray pulses can be used to outrun key damage processes and obtain a single diffraction pattern from a large macromolecule, a virus or a cell before the sample explodes and turns into plasma. The continuous diffraction pattern of non-crystalline objects permits oversampling and direct phase retrieval. Here we show that high-quality diffraction data can be obtained with a single X-ray pulse from a non-crystalline biological sample, a single mimivirus particle, which was injected into the pulsed beam of a hard-X-ray free-electron laser, the Linac Coherent Light Source. Calculations indicate that the energy deposited into the virus by the pulse heated the particle to over 100,000?K after the pulse had left the sample. The reconstructed exit wavefront (image) yielded 32-nm full-period resolution in a single exposure and showed no measurable damage. The reconstruction indicates inhomogeneous arrangement of dense material inside the virion. We expect that significantly higher resolutions will be achieved in such experiments with shorter and brighter photon pulses focused to a smaller area. The resolution in such experiments can be further extended for samples available in multiple identical copies.     

CCN1: a novel inflammation-regulated biphasic immune cell migration modulator

In this study, we performed a comprehensive analysis of the effect of CCN1 on the migration of human immune cells. The molecule CCN1, produced by fibroblasts and endothelial cells, is considered as an important matrix protein promoting tissue repair and immune cell adhesion by binding various integrins. We recently reported that CCN1 therapy is able to suppress acute inflammation in vivo. Here, we show that CCN1 binds to various immune cells including T cells, B cells, NK cells, and monocytes. The addition of CCN1 in vitro enhances both actin polymerization and transwell migration. Prolonged incubation with CCN1, however, results in the inhibition of migration of immune cells by a mechanism that involves downregulation of PI3Kγ, p38, and Akt activation. Furthermore, we observed that immune cells themselves produce constitutively CCN1 and secretion is induced by pro-inflammatory stimuli. In line with this finding, patients suffering from acute inflammation had enhanced serum levels of CCN1. These findings extend the classical concept of CCN1 as a locally produced cell matrix adhesion molecule and suggest that CCN1 plays an important role in regulating immune cell trafficking by attracting and locally immobilizing immune cells.     

STED microscopy reveals that synaptotagmin remains clustered after synaptic vesicle exocytosis

Synaptic transmission is mediated by neurotransmitters that are stored in synaptic vesicles and released by exocytosis upon activation. The vesicle membrane is then retrieved by endocytosis, and synaptic vesicles are regenerated and re-filled with neurotransmitter. Although many aspects of vesicle recycling are understood, the fate of the vesicles after fusion is still unclear. Do their components diffuse on the plasma membrane, or do they remain together? This question has been difficult to answer because synaptic vesicles are too small (approximately 40 nm in diameter) and too densely packed to be resolved by available fluorescence microscopes. Here we use stimulated emission depletion (STED) to reduce the focal spot area by about an order of magnitude below the diffraction limit, thereby resolving individual vesicles in the synapse. We show that synaptotagmin I, a protein resident in the vesicle membrane, remains clustered in isolated patches on the presynaptic membrane regardless of whether the nerve terminals are mildly active or intensely stimulated. This suggests that at least some vesicle constituents remain together during recycling. Our study also demonstrates that questions involving cellular structures with dimensions of a few tens of nanometres can be resolved with conventional far-field optics and visible light.     

Die Wirkung der Lipoid- und Polysaccharid-Komponente endotoxischer Lipopolysaccharide gram-negativer Bakterien auf die Leukozytenkultur

Summary Highly purified lipopolysaccharides derived from gramnegative bacteria (endotoxins) stimulate the migration of leucocytes from cultures of chick leucocytes. This effect, as well as many endotoxic manifestations of the preparationsin vivo (pyrogenicity, toxicity, etc.), is induced by their lipid fraction (lipid A), while the respective species-specific polysaccharide functions as lyophilizing carrier which, fundamentally, can be substituted by other inert carriers (e.g. protein).     

Astronomical pacing of late Palaeocene to early Eocene global warming events

At the boundary between the Palaeocene and Eocene epochs, about 55 million years ago, the Earth experienced a strong global warming event, the Palaeocene-Eocene thermal maximum. The leading hypothesis to explain the extreme greenhouse conditions prevalent during this period is the dissociation of 1,400 to 2,800 gigatonnes of methane from ocean clathrates, resulting in a large negative carbon isotope excursion and severe carbonate dissolution in marine sediments. Possible triggering mechanisms for this event include crossing a threshold temperature as the Earth warmed gradually, comet impact, explosive volcanism or ocean current reorganization and erosion at continental slopes, whereas orbital forcing has been excluded. Here we report a distinct carbonate-poor red clay layer in deep-sea cores from Walvis ridge, which we term the Elmo horizon. Using orbital tuning, we estimate deposition of the Elmo horizon at about 2 million years after the Palaeocene-Eocene thermal maximum. The Elmo horizon has similar geochemical and biotic characteristics as the Palaeocene-Eocene thermal maximum, but of smaller magnitude. It is coincident with carbon isotope depletion events in other ocean basins, suggesting that it represents a second global thermal maximum. We show that both events correspond to maxima in the approximately 405-kyr and approximately 100-kyr eccentricity cycles that post-date prolonged minima in the 2.25-Myr eccentricity cycle, implying that they are indeed astronomically paced.     

Frühe Stadien der Erholung bei bestrahlten ratten und Mäusen

Summary A split dose experiment was performed in 12-, 24- or 32-day-old Wistar rats. About 4000 animals were used. The first dose given was 200 R whole-body X-irradiation in the 2 younger groups, and 260 R in the oldest group. At intervals from 6–48 h after the first, a second irradiation was given in order to estimate the LD50(30). No recovery was seen in terms of the LD50(30) differences between preirradiated and normal animals 6 h after the first dose. At the 12 h interval marked recovery was found in all 3 age groups, but less recovery was apparent at the later intervals.