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Peripheral Localization (peripheral + localization)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

Chromosome topology in normal and aneuploid blastomeres from human embryos

PRENATAL DIAGNOSIS, Issue 12 2007
Jan Diblík
Abstract Objectives To find whether chromosomes 13, 16, 18, 21, 22, X and Y in blastomeres of human embryos are nonrandomly localized, whether their aneuploidy affects their localization and if eventual early inactivation of chromosome X with peripheral localization is present. Methods Relative distances from the nucleus center and edge of 1198 fluorescence in situ hybridization signals in 98 human blastomeres were measured in digital images for comparison with a mathematical model of random distribution in spherical nucleus. Results Comparison with the mathematical model revealed that localization of chromosomes 13, 16, 21, 22, X and Y in normal and aneuploid blastomeres and that of chromosome 18 in normal blastomeres was not significantly different from random distribution. Similarly, chromosome X in blastomeres with more than one X did not appear to have a preferential localization. Only chromosome 18 in aneuploid blastomeres was differently distributed (p < 0.0001) with a shift to the nuclear periphery (p = < 0.0001). Conclusions Peripheral localization of chromosome 18 in aneuploid blastomeres is related to embryo aneuploidy. Conversely, a peripheral localization of the inactive X chromosome was not found in blastomeres from 3-4 day old embryos. These results open the possibility to improve embryo selection after pre-implantation diagnosis. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Plectin deposition at podosome rings requires myosin contractility

CYTOSKELETON, Issue 8 2008
Annica Gad
Abstract Metalloproteinase-dependent tissue invasion requires the formation of podosomes and invadopodia for localized matrix degradation. Actin cytoskeleton remodeling via Arp2/3-mediated actin polymerization is essential for podosome formation, and dynamic microtubules have an important role in maintaining podosome turnover in macrophages and osteoclasts. Little is known, however, about the involvement of the intermediate filament cytoskeleton in formation, stabilization, and turnover of podosomes. Here we show that vimentin intermediate filaments colocalize with the early sites of podosome formation at the stress fiber - focal adhesion interface in cultured vascular smooth muscle cells, but do not directly contribute to podosome formation, or stabilization. In unstimulated A7r5 cells the cytolinker protein plectin poorly colocalized with vimentin and the microdomains, but following induction by phorbol ester accumulated in the rings that surround the podosomes. In plectin-deficient A7r5 cells actin stress fiber remodelling is reduced in response to PDBu, and small podosomes remain localized at stable actin stress fibres. Pharmacological inhibition of actomyosin contractility by blebbistatin leads to an aberrant localization of podosomes away from the cell periphery and induces failure of plectin to surround the outer perimeter of these invasive adhesions. Taken together, we conclude that plectin is involved in growth and maturation of podosomes by reducing focal adhesion and stress fiber turnover, and that actomyosin-dependent contractility is required for the peripheral localization and specific deposition of plectin at the podosome rings. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source]

Development and selection of ,, T cells

IMMUNOLOGICAL REVIEWS, Issue 1 2007
Na Xiong
Summary:, Two main lineages of T cells develop in the thymus: those that express the ,, T-cell receptor (TCR) and those that express the ,, TCR. Whereas the development, selection, and peripheral localization of newly differentiated ,, T cells are understood in some detail, these processes are less well characterized in ,, T cells. This review describes research carried out in this laboratory and others, which addresses several key aspects of ,, T-cell development, including the decision of precursor cells to differentiate into the ,, versus ,, lineage, the ordered differentiation over the course of ontogeny of functional ,, T-cell subsets expressing distinct TCR structures, programming of ordered V, gene rearrangement in the thymus, including a molecular switch that ensures appropriate V, rearrangements at the appropriate stage of development, positive selection in the thymus of ,, T cells destined for the epidermis, and the acquisition by developing ,, T cells of cues that determine their correct localization in the periphery. This research suggests a coordination of molecularly programmed events and cellular selection, which enables specialization of the thymus for production of distinct T-cell subsets at different stages of development. [source]

Induction of Phlorotannins During UV Exposure Mitigates Inhibition of Photosynthesis and DNA Damage in the Kelp Lessonia nigrescens

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2010
Ivan Gómez
Phlorotannins of brown algae are multifunctional compounds with putative roles in herbivore deterrence, antioxidation and as primary cell wall components. Due to their peripheral localization and absorption at short wavelengths, a photoprotective role is suggested. We examined the induction of phlorotannins by artificial UV radiation in the intertidal kelp Lessonia nigrescens and whether they attenuate the inhibition of photosynthesis and DNA damage, two major detrimental effects of UV. The soluble and cell wall-bound fractions of phlorotannins were quantified in blades collected in summer and winter. Major findings were that (1) the synthesis of phlorotannins (both forms) was induced by UV only in summer; (2) the induction was fast (within 3 days); and (3) there was a positive relationship between of the contents of insoluble phlorotannins and the suppression of photoinhibition and DNA damage, measured as formation of cyclobutane pyrimidine dimers and 6-4 photoproducts. Overall, the photoprotective role of phlorotannins appears to respond to an interplay between the external UV stimulus, seasonal acclimation and intrinsic morpho-functional processes. In summer, when algae are naturally exposed to high UV irradiances, soluble phlorotannins are induced, while their transition to insoluble phlorotannins could be related with the growth requirements, as active blade elongation occurs during this season. [source]