Polarised Asymmetric Inheritance of Accumulated Protein Damage in Higher Eukaryotes

Disease-associated misfolded proteins or proteins damaged due to cellular stress are generally disposed via the cellular protein quality-control system. However, under saturating conditions, misfolded proteins will aggregate. In higher eukaryotes, these aggregates can be transported to accumulate in aggresomes at the microtubule organizing center. The fate of cells that contain aggresomes is currently unknown. Here we report that cells that have formed aggresomes can undergo normal mitosis. As a result, the aggregated proteins are asymmetrically distributed to one of the daughter cells, leaving the other daughter free of accumulated protein damage. Using both epithelial crypts of the small intestine of patients with a protein folding disease and Drosophila melanogaster neural precursor cells as models, we found that the inheritance of protein aggregates during mitosis occurs with a fixed polarity indicative of a mechanism to preserve the long-lived progeny

Root canals anatomical study of first upper premolar with two roots using diaphanization technique

Se ha demostrado que la anatomía de los conductos radiculares puede presentar gran cantidad de variaciones anatómicas. Conocer dichas variaciones es de suma importancia para la actividad clínica dental, ya que de esto depende el éxito o el fracaso de los tratamientos endodónticos. Con el propósito de describir la anatomía de los conductos radiculares del primer premolar superior con dos raíces, en esta investigación se diafanizaron 40 dientes, a los cuales se les realizó la apertura cameral para ser permeabilizados con limas de endodoncia tipo K nº 6 y n° 8 y fueron colocados en hipoclorito de sodio al 3,5% por 24 horas para disolver su estructura orgánica. Las muestras fueron lavadas con agua corriente y colocadas en ácido nítrico por 3 días. Posteriormente, fueron sumergidas en agua. Una vez completada la descalcificación, se dio inicio al proceso de deshidratación, el cual consistió en colocar las muestras en concentraciones de alcohol al 60%, 80% y 97%; posteriormente. Los dientes fueron transparentados al ser colocados en salicilato de metilo al 99,9%; una vez completado este procedimiento se inyectó la tinta china en el sistema de conductos. Finalmente, las muestras fueron examinadas de acuerdo con la clasificación de Vertucci para analizar la anatomía de los conductos radiculares. El conducto que se presentó con mayor frecuencia en el primer premolar superior con dos raíces fue el tipo I, seguido del tipo V y del tipo VI. El conducto tipo II se observó en dos muestras y el tipo III sólo en una. No se encontraron los conductos radiculares tipo IV, tipo VII ni tipo [email protected]; [email protected] has been demonstrated that root canals anatomy may present big anatomical variations. It is very important for dental clinical activity to know those variations because success or failure of endodontic treatment relies on suck knowledge. The purpose of this research was to describe the anatomy of the roots canals of two roots first upper premolar. Then, 40 teeth were diaphanized, they were opened (cameral opening) to have them waterproofed with type K endodontic files numbers six and eight, the teeth were submerged in sodium hypochlorite at 3.5% by 24 hours to dissolve their organic structure. The samples were washed with normal water and placed in nitric acid for 3 days, later they were immersed in water. After the decalcification was completed, the process of dehydration was started. It consisted of placing the samples in alcohol concentrations at 60%, 80% and 97%. Then, the teeth were grounded on transparency when placed in methyl salicylate at 99.9%. Once the process finished, china ink was injected into the duct system. Finally, the samples were examined according to Vertucci´s classification for the analysis of root canals anatomy. The most frequently observed duct in the first upper premolar with two roots was type I, followed by types V and VI. The duct type II was observed for two samples whereas type III was seen only in one. Type IV, type VII and type VIII were not found

Polyglutamine Aggregates Are Present in Committed Crypt Cells but Absent in Stem Cells in the Small Intestine of SCA3 Patients

<p>(A) Schematic representation of an intestinal crypt for visualisation of the different cell types present in this tissue. Light micrographs of a 4-μm (B) and 1-μm (C) section of a crypt from an SCA3 patient showing positive staining for anti-Musashi antibody. Note that stem cells are localised in between and on both sides of the morphologically recognizable Paneth cells residing at the base of the crypt. (D) A light micrograph of a crypt of a SCA3 patient showing positive staining for the anti-polyglutamine antibody IC2 in some epithelial cells (arrowheads). The asterisks (marked E–J) show representative positions of cells analyzed by subsequent electron microscopy. (E–J) show digitally modified, pseudo-coloured images of electron micrographs indicating the polyglutamine staining in blue. Differentiated epithelial cells (E), transit epithelial cells (F and I), and Paneth cells (J) contain polyglutamine aggregates (arrowheads). Stem cells (G) are negative for polyglutamine aggregates but occasionally contain micro-aggregates (H). Note that also some electron dense material is stained blue by this digital processing. In (G and H), contours are provided in black dashed lines to indicate the stem cells. Bars: D, 20 μm; E and H, 2 μm; F, 1 μm; G, I and J, 5 μm. (K) Quantification of cells with aggregates in the crypts of two SCA3 patients. As double labelling for aggregates and stem cells failed, only the stem cells that were adjacent to the Paneth cells were counted, because these could be easily identified on this basis.</p

Polyglutamine-Expanded Proteins Form Aggresomes in Hamster O23 Cells and Human HEK293 Cells

<div><p>(A) Percentage of cells containing inclusions 24 h after transfection with a fluorescently tagged huntingtin fragment containing a stretch of either 74 (O23: EGFP-HDQ74) or 119 (HEK293: HDQ119-EYFP) glutamines.</p> <p>(B) Fraction of cells showing either aggresome-like inclusions or non–aggresome-like inclusions (nuclear and/or multiple scattered inclusions). Bars represent standard errors of the mean.</p> <p>(C) Aggresome-like inclusions are either close to (upper panel) or co-localise (lower panel) with the centrosomes (decorated with γ-tubulin antibodies) in interphase O23 cells (likewise in HEK293 cells, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040417#pbio-0040417-sg001" target="_blank">Figure S1</a>).</p> <p>(D) Vimentin microfilaments are redistributed in a cage-like manner around the inclusion, consistent with aggresome morphology. Note that also microtubules (decorated with α-tubulin antibodies) showed partial redistribution to the aggresome.</p> <p>(E) Sequential confocal planes of an aggresome showing both co-localisation with the centrosome and the cage of vimentin. For a full image of this cell see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040417#pbio-0040417-sg001" target="_blank">Figure S1</a>B. DNA is stained with DAPI (blue) and only shown in the overlay images. Bars in (C) and (D) represent 10 μm. Bar in (E) represents 2 μm.</p></div

Polyglutamine Aggregates Are Inherited by De Novo Generated Neuroblast Cells after Mitosis in <i>D. Melanogaster</i>

<div><p>(A) Expression of Htt-Q128 (red) and Pon-GFP (green) was assessed by confocal laser scanning microscopy in whole embryos (Stage 11, in which anterior is at the top). Occasionally, Htt-Q128 aggregates were observed (inset).</p> <p>(B) During mitosis, the aggregated protein Htt-Q128 is associated with only one of the poles in metaphase, anaphase, and telophase, opposing the Pon-GFP crescent, indicative of asymmetric inheritance to de novo generated neuroblast.</p> <p>(C) Spindle pole–associated aggregates were more clearly visualised after α-tubulin (red) staining in Htt-Q128 (cyan), Pon-GFP (green) neuroblasts. DNA is stained with DAPI (blue).</p></div

Aggresomes Do Not Impair Mitotic Cell Division

<div><p>(A) Quantitative analysis of total mitoses in wild-type HEK293 cells and polyglutamine-expressing HEK293-HDQ119 cells. Bars represent standard error of the mean.</p> <p>(B) Relative fraction of mitoses in each population (diffuse, aggresome-containing, and non–aggresome-containing) of HEK293-HDQ119 cells.</p> <p>(C–G) Representative pictures of fixed O23 (C and D) and HEK293 (E–G) aggresome-containing cells in different mitotic phases. The aggresome is associated with only one of the poles during metaphase, anaphase, and telophase. (C) shows that alignment of chromosomes in metaphase appears normal, and (D and F) show that segregation during anaphase-telophase appears to be normal. Similarly, (C and D) show that positioning of the centrosomes is normal, and (E–F) show that distribution of microtubules and (G) cytokinesis are normal. DNA is stained with DAPI (blue). Bars, 5 μm.</p></div