Mapping the β-Cell in 3D at the Nanoscale Using Novel Cellular Electron Tomography and Computational Approaches

Noske, Andrew B.; Marsh, Brad J.

doi:10.1007/978-1-4419-6956-9_8

Cited by 3 publications

(3 citation statements)

References 171 publications

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“…to form new vesicles/ immature granules) the crystalline core is proximal to organelle membrane (Figure 4.1 C) prior to forming new vesicles (Figure 4.1 D). This figure is consistent with previous reports (Noske and Marsh, 2011) and provides a structural key for insulin granule development. Insulin granules were divided into two distinctive 'types'; the 'immature granules' and the 'mature granules' based on their morphology (Figure 4.2).…”

Section: Insulin Granulessupporting

confidence: 82%

Multiple, object-oriented segmentation methods of mammalian cell tomograms

Ruhaiyem¹

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Electron tomography (ET) is a powerful tool for the 3D mapping of the complex 3D sub-cellular structures of cells. It can provide detailed structural data for the extraction, segmentation and annotation (e.g. organelle type, spatial location, volume, surface area, shape and cellular interactions). The ability to map and model sub-cellular volumes is dependent on the quality of the electron tomography data and the ability to segment the resolved features accurately. In particular low signal to noise ratios can resolute in the loss of structural data as well as the incorrect identification of false positives. Manual segmentation is currently considered the gold standard but is subjective and the process is slow. This is highlighted by the finding that the careful segmentation of ~1% of an insulin-secreting HIT-T15 cell required approximately 3600 person-hours (Marsh et al., 2001a). Consequently as the volume and quality of cellular electron tomography data increases so will the need for automated segmentation approaches. Such automated processes will likely require the integration of image filtrations methods, boundary-based and region-based segmentation algorithms and edge detector algorithms. To be of real utility these automated methods must be fast as well as accurate ideally across multiple scales ranging from tissues to molecules. Semiautomated approaches will also be of value if they are able to yield significant gains in data quality and speed.The process of segmentation is principally made difficult by limitations caused by low signal-tonoise ratio (SNR) of volumetric image data typical of that generated by electron tomography.Indeed compared with MRI and CT data-sets electron microscopy has a low SNR and so is good test system for the development of segmentation algorithm. To date the low SNR of electron tomography data has resulted in limited examples of successful automatic segmentation. Improved image pre-processing techniques, such as increasing the SNR through improved sample preparation and imaging, as well as the careful application of denoising algorithms in conjunction with carefully managed segmentation processes have proven most beneficial, but there is still substantial scope for improvement.The aim of this project has been to analyse the pancreatic beta cell tomograms and to conduct a detailed investigation into the structural diversity of their insulin granules, mitochondria and the Golgi apparatus to provide a framework for their classification. The image and structural data obtained by this process was used to guide the development of an image processing pipeline for the iii semi-automated segmentation of specific classes of these organelles on the path to developing more advanced automated processes.Chapter 1 provides an overview of biology of pancreatic beta cells and the process of insulin secretion as well as electron tomography and the motivation for the development of automated segmentation processes.Chapter 2 describes the methods used to prepare and analyse these data sets...

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Section: Insulin Granulessupporting

confidence: 82%

Multiple, object-oriented segmentation methods of mammalian cell tomograms

Ruhaiyem¹

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“…3D reconstruction by ET of each of the two β -cells (designated 'ribbon01' and 'ribbon02') indicated that ribbon01 responded more vigorously to glucose-stimulation than ribbon02 and contained about twice as many branched mitochondria (26 out of a total number of 249 mitochondria) as ribbon02 (with 10 branched mitochondria out of a total of 168 mitochondria). See also the recent Marsh and Noske [33] in this volume. Now, from our electromagnetic point of view, the advantage of branched mitochondria is clear for the generating of a field wave (i.e., the pulsating Ca 2+ oscillations through the whole length of the cell): a single (non rotating) dipole can not generate or initiate a (directed, oriented) field wave.…”

Section: Postulated Electrodynamic Field Charactermentioning

confidence: 98%

Geometric and Electromagnetic Aspects of Fusion Pore Making

Apushkinskaya

Apushkinsky

Booss-Bavnbek

et al. 2011

BetaSys

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For regulated exocytosis, we model the morphology and dynamics of the making of the fusion pore or porosome as a cup-shaped lipoprotein structure (a dimple or pit) on the cytosol side of the plasma membrane. We describe the forming of the dimple by a free boundary problem. We discuss the various forces acting and analyze the magnetic character of the wandering electromagnetic field wave produced by intracellular spatially distributed pulsating (and well observed) release and binding of calcium ions anteceding the bilayer membrane vesicle fusion of exocytosis. Our approach explains the energy efficiency of the observed dimple forming prior to hemifusion and fusion pore, and the observed flickering in secretion. It provides a frame to relate characteristic time length of exocytosis to the frequency, amplitude and direction of propagation of the underlying electromagnetic field wave.Comment: To appear as the closing chapter in a monograph "BetaSys - Systems Biology of Regulated Exocytosis in Pancreatic Beta-Cells", Vol. 4 of the Springer-Verlag Series in Systems Biolog

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“…The diameter of mature granules has been a matter of debate. Chemical fixation yields a diameter of around 350 nm, however, this may well be an artefact and rapid freezing techniques concluded upon a diameter of some 250 nm [55][56][57].…”

Section: Vesicles and Poolsmentioning

confidence: 99%

Fusion pore in exocytosis: More than an exit gate? A β-cell perspective

et al. 2017

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Secretory vesicle exocytosis is a fundamental biological event and the process by which hormones (like insulin) are released into the blood. Considerable progress has been made in understanding this precisely orchestrated sequence of events from secretory vesicle docked at the cell membrane, hemifusion, to the opening of a membrane fusion pore. The exact biophysical and physiological regulation of these events implies a close interaction between membrane proteins and lipids in a confined space and constrained geometry to ensure appropriate delivery of cargo. We consider some of the still open questions such as the nature of the initiation of the fusion pore, the structure and the role of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (SNARE) transmembrane domains and their influence on the dynamics and regulation of exocytosis. We discuss how the membrane composition and protein-lipid interactions influence the likelihood of the nascent fusion pore forming. We relate these factors to the hypothesis that fusion pore expansion could be affected in type-2 diabetes via changes in disease-related gene transcription and alterations in the circulating lipid profile. Detailed characterisation of the dynamics of the fusion pore in vitro will contribute to understanding the larger issue of insulin secretory defects in diabetes.

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Mapping the β-Cell in 3D at the Nanoscale Using Novel Cellular Electron Tomography and Computational Approaches

Cited by 3 publications

References 171 publications

Multiple, object-oriented segmentation methods of mammalian cell tomograms

Multiple, object-oriented segmentation methods of mammalian cell tomograms

Geometric and Electromagnetic Aspects of Fusion Pore Making

Fusion pore in exocytosis: More than an exit gate? A β-cell perspective

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