Direct transfer of viral and cellular proteins from varicella-zoster virus-infected non-neuronal cells to human axons

10.1371/journal.pone.0126081PLoS ONE105e012608

The three-dimensional organization of telomeres in the nucleus of mammalian cells

BACKGROUND: The observation of multiple genetic markers in situ by optical microscopy and their relevance to the study of three-dimensional (3D) chromosomal organization in the nucleus have been greatly developed in the last decade. These methods are important in cancer research because cancer is characterized by multiple alterations that affect the modulation of gene expression and the stability of the genome. It is, therefore, essential to analyze the 3D genome organization of the interphase nucleus in both normal and cancer cells. RESULTS: We describe a novel approach to study the distribution of all telomeres inside the nucleus of mammalian cells throughout the cell cycle. It is based on 3D telomere fluorescence in situ hybridization followed by quantitative analysis that determines the telomeres' distribution in the nucleus throughout the cell cycle. This method enables us to determine, for the first time, that telomere organization is cell-cycle dependent, with assembly of telomeres into a telomeric disk in the G2 phase. In tumor cells, the 3D telomere organization is distorted and aggregates are formed. CONCLUSIONS: The results emphasize a non-random and dynamic 3D nuclear telomeric organization and its importance to genomic stability. Based on our findings, it appears possible to examine telomeric aggregates suggestive of genomic instability in individual interphase nuclei and tissues without the need to examine metaphases. Such new avenues of monitoring genomic instability could potentially impact on cancer biology, genetics, diagnostic innovations and surveillance of treatment response in medicine

<title>Novel spectral bioimaging system as an imaging oximeter in intact rat brain</title>

The use of reflection spectrophotometry to measure the spectra of oxy-hemoglobin and deoxy- hemoglobin, strong absorbers of light in the visible region of the spectrum, is a well established method for determining tissue oxygenation. This type of spectral measurement is typically made with a point-spectrometer and provides information only at a single point. An imaging spectrometer, on the other, can measure the hemoglobin spectra at every pixel in the image, thus providing a two-dimensional (spatial) map of tissue ischemia. A novel spectral bio-imaging system based on the SpectraCube technology, an optical method based on proven Fourier transform (FT) spectroscopy, has been applied successfully in intact rat brain to measure oxy- and deoxy-hemoglobin spectra. Spectral images containing 10,000 spectra were acquired in a rat ventilated with 30% O , and repeated when the inspired gas mixture was switched for 45 seconds to 100% nitrogen. Differences in hemoglobin spectra corresponding to real differences in tissue oxygenation are readily apparent under these two conditions. There is also some evidence that information concerning cytochromes is present in these spectral images, and algorithms are currently being developed to extract the signatures of cytochromes. Details of the spectral bio-imaging system and the results of the measurements made in intact rat brain are discussed

Guidelines for the fitting of anomalous diffusion mean square displacement graphs from single particle tracking experiments.

Single particle tracking is an essential tool in the study of complex systems and biophysics and it is commonly analyzed by the time-averaged mean square displacement (MSD) of the diffusive trajectories. However, past work has shown that MSDs are susceptible to significant errors and biases, preventing the comparison and assessment of experimental studies. Here, we attempt to extract practical guidelines for the estimation of anomalous time averaged MSDs through the simulation of multiple scenarios with fractional Brownian motion as a representative of a large class of fractional ergodic processes. We extract the precision and accuracy of the fitted MSD for various anomalous exponents and measurement errors with respect to measurement length and maximum time lags. Based on the calculated precision maps, we present guidelines to improve accuracy in single particle studies. Importantly, we find that in some experimental conditions, the time averaged MSD should not be used as an estimator