140 research outputs found
Ovarian follicle dynamics in the rat: regulation and flexibility
No full textReproduction is the most important factor for the maintenance of a species. The key event in
this process Is fertilization: combination of haploid cells from male and female parents,
spermatozoon and oocyte, respectively. Before spermatozoa and oocytes are formed and ready
for fertilization many processes have taken place. which are very different for spermatozoa
and oocytes. One of the most striking differences is the continuous production of newly
formed spermatozoa in the fertile male, while the formation of oocytes is already complete
before birth. The oocyte is surrounded by supporting cells. In the complex of the oocyte with
the surrounding cells, called the follicle, close collaboration exists between the oocyte and the
surrounding cells. The main part of this thesis describes the dynamics of follicle development
and the hormonal factors influencing this development
Stepwise androgen receptor dimerization
No full textAndrogen-regulated gene expression is a highly coordinated dynamic process mediated by androgen receptor (AR) ligand binding and DNA binding, and by specific AR protein-protein interactions. The latter include DNA-binding domain (D-box) interactions in AR homodimers, and the interaction of the FQNLF motif in the AR N-terminal domain and the coactivator groove in the ligand-binding domain (N/C interaction). We have studied these interactions in AR homodimerization using quantitative imaging techniques. We found that the initial cytoplasmic intramolecular AR N/C interaction after ligand binding is followed by a D-box-dimerization-dependent transition to intermolecular N/C interaction in a proportion of nuclear ARs. The consecutive steps leading to homodimerization are initiated prior to DNA binding. Our data indicate the presence of nuclear pools of both AR homodimers and monomers. On the basis of AR-regulated reporter assays we propose specificity in regulation of gene expression by AR homodimers and monomers mediated by AR domain interactions. Moreover, our findings elucidate important steps in the spatiotemporal organization of AR intra- and intermolecular interactions
Ex vivo time-lapse confocal imaging of the mouse embryo aorta
No full textTime-lapse confocal microscopy of mouse embryo slices was developed to access and image the living aorta. In this paper, we explain how to label all hematopoietic and endothelial cells inside the intact mouse aorta with fluorescent directly labeled antibodies. Then we describe the technique to cut nonfixed labeled embryos into thick slices that are further imaged by time-lapse confocal imaging. This approach allows direct observation of the dynamic cell behavior in the living aorta, which was previously inaccessible because of its location deep inside the opaque mouse embryo. In particular, this approach is sensitive enough to allow the experimenter to witness the transition from endothelial cells into hematopoietic stem/progenitor cells in the aorta, the first site of hematopoietic stem cell generation during development. The protocol can be applied to observe other embryonic sites throughout mouse development. A complete experiment requires similar to 2 d of practical work
Induction of superovulation in cyclic rats by administration of decreasing doses of recombinant follicle stimulating hormone(Org32489)
No full textAdvanced Level-Set-Based Cell Tracking in Time-Lapse Fluorescence Microscopy (vol 29, pg 852, 2010)
No full textTracking in cell and developmental biology
No full textThe past decade has seen an unprecedented data explosion in biology. It has become evident that in order to take full advantage of the potential wealth of information hidden in the data produced by even a single experiment, visual inspection and manual analysis are no longer adequate. To ensure efficiency, consistency, and completeness in data processing and analysis, computational tools are essential. Of particular importance to many modern live-cell imaging experiments is the ability to automatically track and analyze the motion of objects in time-lapse microscopy images. This article surveys the recent literature in this area. Covering all scales of microscopic observation, from cells, down to molecules, and up to entire organisms, it discusses the latest trends and successes in the development and application of computerized tracking methods in cell and developmental biology. (C) 2009 Elsevier Ltd. All rights reserved
Advanced Level-Set-Based Cell Tracking in Time-Lapse Fluorescence Microscopy
No full textCell segmentation and tracking in time-lapse fluorescence microscopy images is a task of fundamental importance in many biological studies on cell migration and proliferation. In recent years, level sets have been shown to provide a very appropriate framework for this purpose, as they are well suited to capture topological changes occurring during mitosis, and they easily extend to higher dimensional image data. This model evolution approach has also been extended to deal with many cells concurrently. Notwithstanding its high potential, the multiple-level-set method suffers from a number of shortcomings, which limit its applicability to a larger variety of cell biological imaging studies. In this paper, we propose several modifications and extensions to the coupled-active-surfaces algorithm, which considerably improve its robustness and applicability. Our algorithm was validated by comparing it to the original algorithm and two other cell segmentation algorithms. For the evaluation, four real fluorescence microscopy image datasets were used, involving different cell types and labelings that are representative of a large range of biological experiments. Improved tracking performance in terms of precision (up to 11%), recall (up to 8%), ability to correctly capture all cell division events, and computation time (up to nine times reduction) is achieved
Energy minimization methods for cell motion correction and intracellular analysis in live-cell fluorescence microscopy
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