Nucleocytoplasmic sorting of macromolecules following mitosis: fate of nuclear constituents after inhibition of pore complex function

PtK2 cells in which pore complex-mediated transport is blocked by microinjection early in mitosis of a monoclonal antibody (specific for an Mr 68000 pore complex glycoprotein) or of wheat germ agglutinin (WGA) complete cytokinesis. However, their nuclei remain stably arrested in a telophase-like organization characterized by highly condensed chromatin and the absence of nucleoli, indicating a requirement for pore-mediated transport for the reassembly of interphase nuclei. We have now examined this requirement more closely by monitoring the behavior of individual nuclear macromolecules in microinjected cells using immunofluorescence microscopy and have investigated the effect of microinjecting the antibody or WGA on cellular ultrastructure. The absence of nuclear transport did not affect the sequestration into daughter nuclei of components such as DNA, DNA topoisomerase I and the nucleolar protein fibrillarin that are carried through mitosis on chromosomes. On the other hand, lamins, snRNAs and the p68 pore complex glycoprotein, all cytoplasmic during mitosis, remained largely cytoplasmic in the telophase-arrested cells. Electron microscopy showed the nuclei to be surrounded by a doublelayered membrane with some inserted pore complexes. In addition, however, a variety of membranous structures with associated pore complexes was regularly noted in the cytoplasm, suggesting that chromatin may not be essential for the postmitotic formation of pore complexes. We propose that cellular compartmentalization at telophase is a two-step process. First, a nuclear envelope tightly encloses the condensed chromosomes, excluding non-selectively all macromolecules not associated with the chromosomes. Interphase nuclear organization is then progressively restored by selective pore complex-mediated uptake of nuclear proteins from the cytoplasm

Functional role of newly formed pore complexes in postmitotic nuclear reorganization

Many nuclear proteins are released into the cytoplasm at prometaphase and are transported back into the daughter nuclei at the end of mitosis. To determine the role of this reentry in nuclear remodelling during early interphase, we experimentally manipulated nuclear protein uptake in dividing cells. Recently we and others have shown that signal-dependent, pore complex-mediated uptake of nuclear protein is blocked in living cells on microinjection of the lectin wheat germ agglutinin (WGA), or of antibodies such as PI1 that are directed against WGA-binding pore complex glycoproteins. In the present study, we microinjected mitotic PtKz cells with WGA or antibody PIt and followed nuclear reorganization of the daughter cells by immunofluorescence and electron microscopy. The inhibitory effect on nuclear protein uptake was monitored by co-injection of the karyophilic protein nucleoplasmin. When injected by itself early in mitosis, nucleoplasmin became sequestered into the daughter nuclei as they entered telophase. In contrast, nucleoplasmin was excluded from the daughter nuclei in the presence of WGA or antibody PI1 . Although PtKz cells with blocked nuclear protein uptake completed cytokinesis, their nuclei showed a telophaselike organization characterized by highly condensed chromatin surrounded by a nuclear envelope containing a few pore complexes. These findings suggest that pore complexes become functional as early as telophase, in close coincidence with nuclear envelope reformation. They further indicate that the extensive structural rearrangement of the nucleus during the telophase-G1 transition is dependent on the influx of karyophilic proteins from the cytoplasm through the pore complexes, and is not due solely to chromosome- associated components

Dositométrie en odontologie (l'expérience du service de consultations et de traitements dentaires des hôpitaux universitaires de Strasbourg)

STRASBOURG-Medecine (674822101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Les vierges noires : perceptions, significations et utilisation symbolique du XVIIe au XIXe siècle

Schwarze jungfrauen : Wahrnehmung, Bedeutung und Bräuche des 17. bis 19. Janrhunderts „Warum ist sie schwarz ?“ ist sehr oft die erste Frage nach der Begegnung mit einer „Schwarzen Madonna" - das sind Bilder der Jungfrau Maria, die im Mittelpunkt der wichtigsten Wallfahrtsorte annähemd aller katholischer Länder während der Gegenreformation standen. Dieser Aufsatz bietet keine Antwort auf die Frage der Herkunft der Farbe an, sondem versucht zu rekonstruieren, ab wann Verehrer begannen, die Hautfarbe der Bilder als besonders dunkel wahrzuneh-men und welche Bedeutungen sie damit verbanden. Es werden Bedeutungen im Kontext der populären Marienverehrung diskutiert sowie theologische Interpretationen, die schließlich von einem säkular - wissenschaftlichen Paradigma der menschlichen Rassen überlagert wurden. So trägt der Artikel zu einer Diskussion der Geschichte der Wahmehmung von schwarzer Haut in Europa bei und erklärt, wie Bilder, die einst hoch verehrt wurden, zu Kuriositäten degradiert werden konnten, weil sie nicht mehr lesbar waren.The black virgins - perceptions, meanings and usages in the 17th to 19th centuries “Why is she black ?” is very often the first question that comes up in connection with the black madonnas, images of Mary which were at the center of the most important pilgrimage sites of virtually all Catholic countries during the Counter-Reformation. This article does not propose an answer to the question of the color’s origin but attempts to reconstruct when worshipers began to perceive the dark complexion of these images and what meanings they connected to it. The meanings from within the context of popular devotion to Mary are discussed, as well as theological interpretations of the color, and finally the effect of the rise of a scientific paradigm of human races on the perception of the skin color. The article thus contributes to the discussion on the European perception of black skin through history and suggests how images once highly revered can become illegible and therefore unexplainable curiosities.«Pourquoi sont-elles noires ?», telle est la question la plus fréquente que posent les Vierges noires, images qui ont été au centre des lieux de pèlerinage les plus importants de pratiquement tous les pays catholiques à l’époque de la Contre-réforme. Cet article ne répond pas à la question de l’origine de leur coloration, mais tente de saisir à partir de quand les fidèles ont pris consciences de cette particularité et quel est le sens qu’ils lui ont attribué. Les discours internes à la dévotion populaire pour la Vierge Marie sont analysés, ainsi que les interprétations théologiques de la couleur, et que finalement l’émergence plus récente d’un paradigme scientifique dans le classement des races en fonction de la couleur de la peau. La perception de la couleur noire de la peau à travers l’histoire permet de comprendre comment des images objets d’une grande vénération peuvent devenir des curiosités incompréhensibles parce qu’illisibles.Scheer Monique, Blaha-Peillex Nathalie. Les vierges noires : perceptions, significations et utilisation symbolique du XVIIe au XIXe siècle. In: Revue des sciences sociales, N°34, 2005. Le rapport à l'image. pp. 76-83

The chromatin remodelling complex WSTF–SNF2h interacts with nuclear myosin 1 and has a role in RNA polymerase I transcription

Nuclear actin and myosin 1 (NM1) are key regulators of gene transcription. Here, we show by biochemical fractionation of nuclear extracts, protein–protein interaction studies and chromatin immunoprecipitation assays that NM1 is part of a multiprotein complex that contains WICH, a chromatin remodelling complex containing WSTF (Williams syndrome transcription factor) and SNF2h. NM1, WSTF and SNF2h were found to be associated with RNA polymerase I (Pol I) and ribosomal RNA genes (rDNA). RNA interference-mediated knockdown of NM1 and WSTF reduced pre-rRNA synthesis in vivo, and antibodies to WSTF inhibited Pol I transcription on pre-assembled chromatin templates but not on naked DNA. The results indicate that NM1 cooperates with WICH to facilitate transcription on chromatin

Delayed cortical gray matter development in neonates with severe congenital heart disease

BACKGROUND: This study aimed to assess cortical gray matter growth and maturation in neonates with congenital heart disease (CHD). METHODS: Thirty-one (near) term neonates with severe CHD (8 univentricular heart malformation (UVH), 21 d-transposition of great arteries (d-TGA) and 2 aortic coarctation) underwent cerebral MRI before (postnatal-day 7) and after (postnatal-day 24) surgery. Eighteen controls with similar gestational age had one MRI (postnatal-day 23). Cortical gray matter volume (CGM), inner cortical surface (iCS), and median cortical thickness were extracted as measures of volumetric growth, and gyrification index (GI) as measure of maturation. RESULTS: Over a median of 18 d, CGM increased by 21%, iCS by 17%, thickness and GI both by 9%. Decreased postoperative CGM and iCS were seen for CHD compared to controls (P values < 0.01), however with similar thickness and GI. UVH showed lower postoperative iCS, thickness (P values < 0.05) and GI (P value < 0.01) than d-TGA and controls. Infants requiring preoperative balloon-atrioseptostomy (BAS, 61%) had reduced postoperative CGM, iCS, and GI (P values < 0.05). CONCLUSION: Infants with severe CHD show reduced cortical volumes compared to controls with gyrification being delayed in UVH, but not in d-TGA. Infants requiring BAS show higher risk of impaired cortical volume and gyrification

Delayed cortical gray matter development in neonates with severe congenital heart disease

Background: This study aimed to assess cortical gray matter growth and maturation in neonates with congenital heart disease (CHD). Methods: Thirty-one (near) term neonates with severe CHD (8 univentricular heart malformation (UVH), 21 d-transposition of great arteries (d-TGA) and 2 aortic coarctation) underwent cerebral MRI before (postnatal-day 7) and after (postnatal-day 24) surgery. Eighteen controls with similar gestational age had one MRI (postnatal-day 23). Cortical gray matter volume (CGM), inner cortical surface (iCS), and median cortical thickness were extracted as measures of volumetric growth, and gyrification index (GI) as measure of maturation. Results: Over a median of 18 d, CGM increased by 21%, iCS by 17%, thickness and GI both by 9%. Decreased postoperative CGM and iCS were seen for CHD compared to controls (P values <0.01), however with similar thickness and GI. UVH showed lower postoperative iCS, thickness (P values <0.05) and GI (P value <0.01) than d-TGA and controls. Infants requiring preoperative balloon-atrioseptostomy (BAS, 61%) had reduced postoperative CGM, iCS, and GI (P values <0.05). Conclusion: Infants with severe CHD show reduced cortical volumes compared to controls with gyrification being delayed in UVH, but not in d-TGA. Infants requiring BAS show higher risk of impaired cortical volume and gyrification