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991.
Timpson P McGhee EJ Erami Z Nobis M Quinn JA Edward M Anderson KI 《Journal of visualized experiments : JoVE》2011,(56):e3089
Cell migration is fundamental to many aspects of biology, including development, wound healing, the cellular responses of the immune system, and metastasis of tumor cells. Migration has been studied on glass coverslips in order to make cellular dynamics amenable to investigation by light microscopy. However, it has become clear that many aspects of cell migration depend on features of the local environment including its elasticity, protein composition, and pore size, which are not faithfully represented by rigid two dimensional substrates such as glass and plastic. Furthermore, interaction with other cell types, including stromal fibroblasts and immune cells, has been shown to play a critical role in promoting the invasion of cancer cells. Investigation at the molecular level has increasingly shown that molecular dynamics, including response to drug treatment, of identical cells are significantly different when compared in vitro and in vivo. Ideally, it would be best to study cell migration in its naturally occurring context in living organisms, however this is not always possible. Intermediate tissue culture systems, such as cell derived matrix, matrigel, organotypic culture (described here) tissue explants, organoids, and xenografts, are therefore important experimental intermediates. These systems approximate certain aspects of an in vivo environment but are more amenable to experimental manipulation such as use of stably transfected cell lines, drug treatment regimes, long term and high-resolution imaging. Such intermediate systems are especially useful as proving grounds to validate probes and establish parameters required to image the dynamic response of cells and fluorescent reporters prior to undertaking imaging in vivo. As such, they can serve an important role in reducing the need for experiments on living animals. 相似文献
992.
Localization of antigens associated with adherens junctions, desmosomes, and hemidesmosomes during murine molar morphogenesis 总被引:3,自引:0,他引:3
993.
M Gloerich JP Ten Klooster MJ Vliem T Koorman FJ Zwartkruis H Clevers JL Bos 《Nature cell biology》2012,14(8):793-801
The microvillus brush border at the apex of the highly polarized enterocyte allows the regulated uptake of nutrients from the intestinal lumen. Here, we identify the small G protein Rap2A as a molecular link that couples the formation of microvilli directly to the preceding cell polarization. Establishment of apicobasal polarity, which can be triggered by the kinase LKB1 in single, isolated colon cells, results in enrichment of PtdIns(4,5)P(2) at the apical membrane. The subsequent recruitment of phospholipase D1 allows polarized accumulation of phosphatidic acid, which provides a local cue for successive signalling by the guanine nucleotide exchange factor PDZGEF, the small G protein Rap2A, its effector TNIK, the kinase MST4 and, ultimately, the actin-binding protein Ezrin. Thus, epithelial cell polarization is translated directly into the acquisition of brush borders through a small G protein signalling module whose action is positioned by a cortical lipid cue. 相似文献
994.
Mariam Siala Radhouane Gdoura Hela Fourati Markus Rihl Benoit Jaulhac Mohamed Younes Jean Sibilia Sofien Baklouti Naceur Bargaoui Slaheddine Sellami Abdelghani Sghir Adnane Hammami 《Arthritis research & therapy》2009,11(4):R102
Introduction
Broad-range rDNA PCR provides an alternative, cultivation-independent approach for identifying bacterial DNA in reactive and other form of arthritis. The aim of this study was to use broad-range rDNA PCR targeting the 16S rRNA gene in patients with reactive and other forms of arthritis and to screen for the presence of DNA from any given bacterial species in synovial fluid (SF) samples.Methods
We examined the SF samples from a total of 27 patients consisting of patients with reactive arthritis (ReA) (n = 5), undifferentiated arthritis (UA) (n = 9), rheumatoid arthritis (n = 7), and osteoarthritis (n = 6) of which the latter two were used as controls. Using broad-range bacterial PCR amplifying a 1400 bp fragment from the 16S rRNA gene, we identified and sequenced at least 24 clones from each SF sample. To identify the corresponding bacteria, DNA sequences were compared to the EMBL (European Molecular Biology Laboratory) database.Results
Bacterial DNA was identified in 20 of the 27 SF samples (74, 10%). Analysis of a large number of sequences revealed the presence of DNA from more than one single bacterial species in the SF of all patients studied. The nearly complete sequences of the 1400 bp were obtained for most of the detected species. DNA of bacterial species including Shigella species, Escherichia species, and other coli-form bacteria as well as opportunistic pathogens such as Stenotrophomonas maltophilia and Achromobacter xylosoxidans were shared in all arthritis patients. Among pathogens described to trigger ReA, DNA from Shigella sonnei was found in ReA and UA patients. We also detected DNA from rarely occurring human pathogens such as Aranicola species and Pantoea ananatis. We also found DNA from bacteria so far not described in human infections such as Bacillus niacini, Paenibacillus humicus, Diaphorobacter species and uncultured bacterium genera incertae sedis OP10.Conclusions
Broad-range PCR followed by cloning and sequencing the entire 16S rDNA, allowed the identification of the bacterial DNA environment in the SF samples of arthritic patients. We found a wide spectrum of bacteria including those known to be involved in ReA and others not previously associated with arthritis. 相似文献995.
Little is known about the composition and function of the mycorrhizal fungal community in riparian areas, or its importance
in competitive interactions between Populus fremontii, a dominant tree in southwestern United States riparian forests which forms arbuscular and ectomycorrhizas, and Tamarix ramosissima, an introduced tree species that has spread into riparian areas. The objectives of this study were to determine the mycorrhizal
status of Tamarixand to evaluate the effect of mycorrhizal fungal inoculation on Tamarix growth and on the coexistence between Tamarix and Populus.Arbuscular mycorrhizal fungal colonization of Tamarix was very low in both field and greenhouse grown roots, but levels of colonization by dark septate endophytes were high. Fungal
inoculation had little effect on Tamarix seedling growth in monoculture. When Populus and Tamarix were grown together in a greenhouse pot experiment, fungal inoculation reduced the height and biomass of Tamarix but had no effect on Populus. Fungal inoculation shifted coexistence ratios. When Tamarix and Populuswere grown together, Tamarixplants averaged 20 of pot biomass in the uninoculated control but only 5 of pot biomass in the inoculated treatment. These
results indicate that Tamarix is non-mycotrophic and that in this greenhouse experiment inoculation altered patterns of coexistence between Populus and Tamarix. 相似文献
996.
Michel Fausther Jessica R. Goree élise G. Lavoie Alicia L. Graham Jean Sévigny Jonathan A. Dranoff 《PloS one》2015,10(3)
The major sources of scar-forming myofibroblasts during liver fibrosis are activated hepatic stellate cells (HSC) and portal fibroblasts (PF). In contrast to well-characterized HSC, PF remain understudied and poorly defined. This is largely due to the facts that isolation of rodent PF for functional studies is technically challenging and that PF cell lines had not been established. To address this, we have generated two polyclonal portal myofibroblast cell lines, RGF and RGF-N2. RGF and RGF-N2 were established from primary PF isolated from adult rat livers that underwent culture activation and subsequent SV40-mediated immortalization. Specifically, Ntpdase2/Cd39l1-sorted primary PF were used to generate the RGF-N2 cell line. Both cell lines were functionally characterized by RT-PCR, immunofluorescence, immunoblot and bromodeoxyuridine-based proliferation assay. First, immortalized RGF and RGF-N2 cells are positive for phenotypic myofibroblast markers alpha smooth muscle actin, type I collagen alpha-1, tissue inhibitor of metalloproteinases-1, PF-specific markers elastin, type XV collagen alpha-1 and Ntpdase2/Cd39l1, and mesenchymal cell marker ecto-5’-nucleotidase/Cd73, while negative for HSC-specific markers desmin and lecithin retinol acyltransferase. Second, both RGF and RGF-N2 cell lines are readily transfectable using standard methods. Finally, RGF and RGF-N2 cells attenuate the growth of Mz-ChA-1 cholangiocarcinoma cells in co-culture, as previously demonstrated for primary PF. Immortalized rat portal myofibroblast RGF and RGF-N2 cell lines express typical markers of activated PF-derived myofibroblasts, are suitable for DNA transfection, and can effectively inhibit cholangiocyte proliferation. Both RGF and RGF-N2 cell lines represent novel in vitro cellular models for the functional studies of portal (myo)fibroblasts and their contribution to the progression of liver fibrosis. 相似文献
997.
Jean‐Bernard Dongmo Champlain Djieto‐Lordon Pierre Ngassam 《African Journal of Ecology》2015,53(3):312-319
Evidence of sexual dimorphism in body size and the existence of morphological differences were studied in the yellow‐whiskered Greenbul Andropadus latirostris. We measured fresh body weight and seven linear parameters of external morphology in mature individuals of this species from three localities in Cameroon and two localities in Ghana. Based on general linear model analysis, we showed that males are significantly larger than females. We applied a discriminant analysis on eight morphometric parameters to create two discriminant functions, one for each country. The overall rate of well‐classified birds was 93.3% for Cameroon and 92.7% for Ghana. Wing length was the most accurate character for separating the sexes in both study areas. Significant sexual size dimorphism might be explained by sexual selection on male competitive ability and intraspecific competition. We also found morphological divergence in this species between the two study areas, including marked differences in size of the beak. This work provides statistical evidence of a substantial sexual size dimorphism in A. latirostris and geographic variation in morphology. 相似文献
998.
Lieve de Clercq Claude Remacle Jean Demal 《In vitro cellular & developmental biology. Plant》1977,13(2):85-90
Summary The use of a semi-natural medium (Eagle’s MEM supplemented with chicken embryo extract) appears to be satisfactory for ovarian
and testicular fragment cultures ofCarassius auratus. The male germ cells show a normal degeneration which might be attributed to a lack of pituitary hormones: gonadotropic and,
possibly, somatotropic hormone. The ovarian fragments maintain a normal organization during 21 days of culture. Only the occytes
in late vitellogenesis massively atresiate at the beginning of culture. The addition of fetal bovine serum to this medium
produces surprising effects on the testicular explants, particularly on the spermatogonial mitoses. This might be attributed
to the presence of STH and androgen in the serum. The modifications of ovarian explants, on the other hand, are identical
to those observed with Eagle’s MEM supplemented with chicken embryo extract. M 199 has been tested as a synthetic medium;
the preliminary results are encouraging. Testosterone, when added to the semi-natural medium, permits complete spermatogenesis
in the testicular fragments during the 21 days of culture, but does not produce any effect on the ovarian explants. 相似文献
999.
Bonamy C Labarre J Cazaubon L Jacob C Le Bohec F Reyes O Leblon G 《Journal of biotechnology》2003,104(1-3):301-309
IS1207 is the insertion most frequently found among the spontaneous mutations that abolish the activity of an Escherichia coli phage lambda cI gene integrated in the Corynebacterium Brevibacterium lactofermentum ATCC21086 genome. We examined the transposition of transposon-like structures composed of a selective kanamycin resistance gene (aph3), and one or two IS1207 sequences. One of these, the Tn5531 transposon, transposed efficiently in Corynebacterium glutamicum. A replicative and a non-replicative Tn5531 delivery vector were used in Tn5531 mutagenesis. As IS1207, transposon Tn5531 shows a high frequency of transposition and mutagenesis, and a low target specificity. These features make of Tn5531 an adequate choice for gene identification and gene tagging experiments. 相似文献
1000.