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Useful Model System (useful + model_system)
Selected AbstractsCentrioles to basal bodies in the spermiogenesis of Mastotermes darwiniensis (Insecta, Isoptera)CYTOSKELETON, Issue 5 2009Maria Giovanna Riparbelli Abstract In addition to their role in centrosome organization, the centrioles have another distinct function as basal bodies for the formation of cilia and flagella. Centriole duplication has been reported to require two alternate assembly pathways: template or de novo. Since spermiogenesis in the termite Mastotermes darwiniensis lead to the formation of multiflagellate sperm, this process represents a useful model system in which to follow basal body formation and flagella assembly. We present evidence of a possible de novo pathway for basal body formation in the differentiating germ cell. This cell also contains typical centrosomal proteins, such as centrosomin, pericentrin-like protein, ,-tubulin, that undergo redistribution as spermatid differentiation proceeds. The spermatid centrioles are long structures formed by nine doublet rather than triplet microtubules provided with short projections extending towards the surrounding cytoplasm and with links between doublets. The sperm basal bodies are aligned in parallel beneath the nucleus. They consist of long regions close to the nucleus showing nine doublets in a cartwheel array devoid of any projections; on the contrary, the short region close to the plasma membrane, where the sperm flagella emerge, is characterized by projections similar to those observed in the centrioles linking the basal body to the plasma membrane. It is hypothesized that this appearance is in connection with the centriole elongation and further with the flagellar axonemal organization. Microtubule doublets of sperm flagellar axonemes are provided with outer dynein arms, while inner arms are rarely visible. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] In vitro Epstein-Barr virus-immortalized lymphoma cell line carrying t(9;14)(p13;q32) chromosome abnormality, derived from splenic lymphoma with villous lymphocytesINTERNATIONAL JOURNAL OF CANCER, Issue 2 2006Masanori Daibata Abstract We herein describe splenic lymphoma with villous lymphocytes (SLVL) carrying t(9;14)(p13;q32). The t(9;14)(p13;q32) is a rare reciprocal chromosome translocation found in a subset of B-cell malignancies, mainly in low-grade non-Hodgkin's lymphomas. In t(9;14)(p13;q32), PAX-5 gene on 9p13 is involved with the immunoglobulin heavy-chain gene on 14q32. It has been thought that the deregulated expression of PAX-5 as a result of t(9;14)(p13;q32) may contribute to abnormal cell proliferation. Although continuous cell lines are invaluable tools for studying lymphomagenesis in the t(9;14)(p13;q32)-bearing lymphomas, establishment of such cell lines is extremely difficult since they are usually mature B-cell malignancies. In an attempt to transform the SLVL cells into a proliferating cell line, we examined the responses of the cells to infection by Epstein-Barr virus (EBV). SLVL cells were found to be susceptible to immortalization by EBV, resulting in a permanent cell line. The cell line, designated SL-15, possessed the t(9;14)(p13;q32). Genotype analysis and immunophenotype profiles confirmed that the cell line arose from the primary lymphoma cells. The cells had characteristic cytoplasmic villi. SL-15 cells has been growing over 2 years equivalent to 350,400 population doubling levels without proliferative crisis that is often observed in EBV-positive lymphoblastoid cell lines. Furthermore, SL-15 cells, when inoculated into nude mice, formed t(9;14)(p13;q32)-bearing tumors with cytoplasmic villi. The validated SLVL-derived cell line provide a useful model system to study molecular biology of t(9;14)(p13;q32)-bearing B-cell malignancies as well as lymphomagenesis of SLVL in vitro and in vivo. © 2005 Wiley-Liss, Inc. [source] Ecosystem science and human,environment interactions in the Hawaiian archipelagoJOURNAL OF ECOLOGY, Issue 3 2006PETER VITOUSEK Summary 1Tansley's ecosystem concept remains a vital framework for ecological research in part because the approach facilitates interdisciplinary analyses of ecological systems. 2Features of the Hawaiian Islands , particularly the nearly orthogonal variation in many of the factors that control variation among ecosystems elsewhere , make the archipelago a useful model system for interdisciplinary research designed to understand fundamental controls on the state and dynamics of ecosystems, and their consequences for human societies. 3Analyses of rain forest sites arrayed on a substrate age gradient from c. 300 years to over 4 million years across the Hawaiian archipelago demonstrate that the sources of calcium and other essential cations shift from > 80% rock-derived in young sites to > 80% derived from marine aerosol on substrates older than 100 000 years. Rock-derived phosphorus is retained longer within ecosystems, but eventually long-distance transport of continental dust from Asia becomes the most important source of phosphorus. 4A biogeochemical feedback from low nutrient availability to efficient resource use by trees to slow decomposition and nutrient regeneration accentuates the geochemically driven pattern of low phosphorus availability and phosphorus limitation to net primary productivity in the oldest site. 5Variations in ecosystem biogeochemistry across the archipelago shaped the development and sustainability of Polynesian agricultural systems in the millennium between their discovery of Hawai'i and contact by Europeans. Irrigated pondfields were largely confined to stream valleys on the older islands, while rain-fed dryland systems occupied a narrow zone of fertile, well-watered soils on the younger islands. 6The ecosystem approach often represents the most appropriate level of organization for analyses of human influences on ecological systems; it can play a central role in the design and analysis of alternative agricultural, industrial and residential systems that could reduce the human footprint on the Earth. [source] The influence of extracellular matrix and prolactin on global gene expression profiles of primary bovine mammary epithelial cells in vitroANIMAL GENETICS, Issue 1 2010L. G. Riley Summary An in vitro bovine mammosphere model was characterized for use in lactational biology studies using a functional genomics approach. Primary bovine mammary epithelial cells cultured on a basement membrane, Matrigel, formed three-dimensional alveoli-like structures or mammospheres. Gene expression profiling during mammosphere formation by high-density microarray analysis indicated that mammospheres underwent similar molecular and cellular processes to developing alveoli in the mammary gland. Gene expression profiles indicated that genes involved in milk protein and fat biosynthesis were expressed, however, lactose biosynthesis may have been compromised. Investigation of factors influencing mammosphere formation revealed that extracellular matrix (ECM) was responsible for the initiation of this process and that prolactin (Prl) was necessary for high levels of milk protein expression. CSN3 (encoding ,-casein) was the most highly expressed casein gene, followed by CSN1S1 (encoding ,S1-casein) and CSN2 (encoding ,-casein). Eighteen Prl-responsive genes were identified, including CSN1S1, SOCS2 and CSN2, however, expression of CSN3 was not significantly increased by Prl and CSN1S2 was not expressed at detectable levels in mammospheres. A number of novel Prl responsive genes were identified, including ECM components and genes involved in differentiation and apoptosis. This mammosphere model is a useful model system for functional genomics studies of certain aspects of dairy cattle lactation. [source] Germanates of 1D Chains, 2D Layers, and 3D Frameworks Built from Ge,O Clusters by Using Metal-Complex Templates: Host,Guest Symmetry and Chirality TransferCHEMISTRY - AN ASIAN JOURNAL, Issue 10 2007Guang-Zhen Liu Abstract The self-assembly of Ge,O polyhedra by metal-complex templates leads to initial examples of open germanate structures under mild solvothermal conditions. These materials are constructed from Ge,O cluster building bocks (Ge7X19 (X=O, OH, or F) or Ni@Ge14O24(OH)3) and span the full range of dimensionalities from 1D chains of Ge7O13(OH)2F3,Cl,2[Ni(dien)2] (FJ- 6) to 2D layers of Ge7O14F3,0.5[In(dien)2],0.5H3dien, 2H2O (1) and 3D frameworks of Ni@ Ge14O24(OH)3,2[Ni(L)3] (FJ- 1,a/FJ- 1,b) (dien=diethylenetriamine, L=ethylenediamine (en) or 1,2-diaminopropane (enMe)). The Ge7X19 cluster in FJ- 6 and 1 is formed by condensation of four GeX4 tetrahedra, two GeX5 trigonal bipyramids, and one GeX6 octahedron with a ,3 -O atom at the center of the cluster, whereas the Ni@ Ge14O24(OH)3 cluster in FJ- 1,a/FJ- 1,b is formed by condensation of nine peripheral GeO4 tetrahedra and five interior GeO3Ni units with one ,5 -Ni atom at the center of the cluster. FJ- 6 is characterized by a pair of racemic Ge7O14(OH)2F3 cluster chains and represents only one example of 1D germanates; 1 exhibits unique germanate layers with uniform 10-membered-ring apertures encapsulating an unknown indium complex, and the framework structure of FJ- 1,a/FJ- 1,b with large 24-membered-ring channels is the first example of porous materials that contain metal,metal bonds (Ge2+Ni+). These initial examples of germanates from metal-complex templates provide a useful model system for understanding the mechanisms of host,guest interactions, which may further facilitate the design and development of new porous materials "on demand". It is shown that the symmetry and configuration of the guest metal complex can be imprinted onto the host inorganic framework through hydrogen bonding between host and guest. [source] EXPRESSION OF P2X PURINOCEPTORS IN PC12 PHAEOCHROMOCYTOMA CELLSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2007Ji-Hu Sun SUMMARY 1The PC12 cell line, which was cloned from a rat adrenal phaeochromocytoma, is a useful model system. It expresses neuronal properties after treatment with nerve growth factor (NGF). The nervous system-specific P2X receptor subtype P2X2 was initially cloned from PC12 cells, but little is known about the expression of other subtypes of P2X receptors in PC12 cells. The aim of the present study was to investigate whether PC12 cells express the other P2X receptors when exposed to NGF. 2Reverse transcription,polymerase chain reaction at the mRNA level and immunocytochemisty at the protein level showed that, among the seven P2X purinoceptor subtypes, only P2X2 was found to be expressed in undifferentiated PC12 phaeochromocytoma cells, but all seven P2X purinoceptor subtypes were expressed in differentiated PC12 cells treated with 50 µg/mL NGF. 3Electrophysiological recordings indicated that ATP (30 µmol/L) but not ,,,-methylene ATP (,,,-meATP; 30 µmol/L) evoked an inward current in undifferentiated PC12 cells, but both ,,,-meATP and ATP evoked inward currents in differentiated PC12 cells. The results indicate that the NGF-induced P2X receptors expressed in PC12 cells are functional channels. 4The present study suggests that the NGF-induced neuronal phenotype of PC12 cells may be a model for the study of P2X heteromeric receptors. [source] ECOLOGICAL DIFFERENTIATION AND DIPLOID SUPERIORITY ACROSS A MOVING PLOIDY CONTACT ZONEEVOLUTION, Issue 1 2007Richard J. A. Buggs Plant polyploid complexes provide useful model systems for distinguishing between adaptive and nonadaptive causes of parapatric distributions in closely related lineages. Polyploidy often gives rise to morphological and physiological changes, which may be adaptive to different environments, but separate distributions may also be maintained by reproductive interference caused by postzygotic reproductive isolation. Here, we test the hypothesis that diploid and descendent polyploid races of the wind-pollinated herb Mercurialis annua, which are found in parapatry over an environmental gradient in northeast Spain, are differentiated in their ecophysiology and life history. We also ask whether any such differences represent adaptations to their different natural environments. On the basis of a series of reciprocal transplant experiments in the field, and experiments under controlled conditions, we found that diploid and polyploid populations of M. annua are ecologically differentiated, but that they do not show local adaptation; rather, the diploids have higher fitness than the polyploids across both diploid- and polyploid-occupied regions. In fact, diploids are currently displacing polyploids by advancing south on two separate fronts in Spain, and previous work has shown that this displacement is being driven to a large extent by asymmetrical pollen swamping. Our results here suggest that ecophysiological superiority of the diploids may also be contributing to their expansion. [source] | |||||||||||||