Three-dimensional localisation of DNA in the nucleolus of Spirogyra by correlated optical tomography and serial ultra-thin sectioning

1990 ◽  
Vol 95 (3) ◽  
pp. 343-352
Author(s):  
E.G. Jordan ◽  
D.J. Rawlins
Keyword(s):  
Optical Microscopy ◽  
Optical Tomography ◽  
Three Dimensional ◽  
Dense Fibrillar Component ◽  
Fibrillar Centre ◽  
Thin Sectioning ◽  
Distribution Matching ◽  
Fibrillar Component ◽  
Dapi Fluorescence

Spirogyra nucleoli were shown by three-dimensional optical microscopy of DAPI fluorescence to contain DNA with a pattern and distribution matching those of the fibrillar centres. This was confirmed using different species with nucleoli showing different sizes of fibrillar centre. Much lower levels of fluorescence were seen corresponding to the dense fibrillar component. Nearly all the DAPI fluorescence arises from the fibrillar centres or from regions very close to their surface, indicating that this is the site of nucleolar transcription.

scholarly journals A miniaturized optical tomography platform for volumetric imaging of engineered living systems

Lab on a Chip ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 550-561 ◽  
Author(s):  
Adem Polat ◽  
Shabir Hassan ◽  
Isa Yildirim ◽  
Luis Eduardo Oliver ◽  
Maryam Mostafaei ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Biological Sample ◽  
Optical Tomography ◽  
Three Dimensional ◽  
Living Systems ◽  
Volumetric Imaging ◽  
Non Invasive ◽  
3D Information

Volumetric optical microscopy approaches that enable acquisition of three-dimensional (3D) information from a biological sample are attractive for numerous non-invasive imaging applications.

Three-dimensional electron microscopy of the internal nucleolus-associated chromatin and of the nucleolar vacuoles during early germination of Sinapis alba

1986 ◽  
Vol 82 (1) ◽  
pp. 53-71
Author(s):  
R. Deltour ◽  
H. Mosen ◽  
R. Bronchart
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Sinapis Alba ◽  
Serial Sections ◽  
Dense Fibrillar Component ◽  
Dimensional Electron ◽  
Early Germination ◽  
Fibrillar Component ◽  
Dense Chromatin ◽  
Nucleolar Vacuole

Spatial relationships between the internal nucleolus-associated chromatin (NAC) and the numerous nucleolar vacuoles that appear during early germination have been studied in nucleoli of quiescent (non-germinated) and early germinating embryos of Sinapis using serial sections. In quiescent non-vacuolated nucleoli, the transcriptionally inactive internal NAC is a short strand about 900 nm thick that in cross-section appears as heterogeneous fibrillar centres (FCs). At 4 and 6 h after germination one or several large networks of interconnected nucleolar vacuoles develop around the dispersing internal NAC. Clumps of dense chromatin are still present within the nucleolar vacuoles and are probably unfolding into deoxyribonucleoprotein (DNP) fibres (about 110 nm thick), which rapidly intrude within the nucleolar body and form thin chromatin threads. At 24 h after germination the internal NAC is more dispersed and forms, for its greatest part, a long thread (about 240 nm in diameter) wrapped up with a few dense fibrillar component, the whole forming the first outline of a nucleolonema. In cross-section most of the internal NAC appears as homogeneous FCs but short portions remain more condensed and appear as heterogeneous FCs always associated with a nucleolar vacuole. From 48 h the internal NAC is a longer thinner strand (about 160 nm in diameter), probably continuous and surrounded entirely by a homogeneous muff of dense fibrillar component, the whole forming a typical nucleolonema (about 950 nm thick) meandering throughout the nucleolus. Small amounts of the internal NAC still remain undispersed in the form of heterogeneous FCs associated with a nucleolar vacuole. The repeated association of nucleolar vacuoles and dispersing internal NAC suggests that they could play a role in chromatin dispersion and, or, activation by creating a favourable microenvironment.

Ultrastructural organization, sites of transcription and distribution of fibrillar centres in the nucleolus of the mouse oocyte

1981 ◽  
Vol 48 (1) ◽  
pp. 105-126
Author(s):  
C. Mirre ◽  
A. Stahl
Keyword(s):  
Time Course ◽  
Secondary Constriction ◽  
Three Dimensional ◽  
Ultrastructural Organization ◽  
Late Pachytene ◽  
Uridine Incorporation ◽  
Fibrillar Centre ◽  
Nucleolar Organizers ◽  
Dimensional Reconstruction ◽  
Fibrillar Component

The emergence of newly formed nucleoli and their development have been studied in mouse oocytes from pachytene to diplotene stages. At mid-pachytene, the nucleolus first appears as a fibrillar centre surrounded by a layer of electron-dense fibrils and penetrated by chromatin fibres emanating from the secondary constriction region of the nucleolar bivalent. Since this bivalent contains 2 paired nucleolar organizers, 2 nucleoli are formed in a symmetrical fashion. At advanced pachytene, the nucleoli are extended by strands of fibrillar component which become fibrillogranular distally. The 2 nucleoli fuse together at late pachytene. At diplotene, the nucleolus becomes large and reticulated. The development of the nucleolonema coincides with the appearance of numerous secondary fibrillar centres. Three-dimensional reconstruction of the reticulated nucleolus shows that the number of fibrillar centres largely exceeds that of nucleolar organizers. Radioautography after [3H]uridine incorporation demonstrates that during the first step of nucleologenesis the labelling is limited to the layer of electron-dense fibrils surrounding the fibrillar centre. Study of the time course of tritiated uridine incorporation from pachytene to diplotene shows that the labelling extends with the extending strands of fibrillar component. In the fully developed nucleolus, all fibrillar strands are labelled and contain, therefore, actively transcribed rDNA. These observations suggest that the rDNA, which is initially compacted in the primary fibrillar centre at the onset of nucleogenesis, progressively unravels and becomes distributed throughout the fibrillar parts of the nucleolonema. The lack of labelling of the secondary fibrillar centres suggests that they are zones of inactivity of the ribosomal genes where the rDNA remains locally compacted. A model of the ultrastructural organization of the nucleolus is proposed based on our observations.

Ultrastructure and activity of the nucleolar organizer in the mouse oocyte during meiotic prophase

1978 ◽  
Vol 31 (1) ◽  
pp. 79-100
Author(s):  
C. Mirre ◽  
A. Stahl
Keyword(s):  
Ribosomal Rna ◽  
Meiotic Prophase ◽  
Nucleolar Organizer ◽  
Mouse Oocyte ◽  
Synthetic Activity ◽  
Dense Fibrillar Component ◽  
Rdna Transcription ◽  
Lateral Element ◽  
Fibrillar Centre ◽  
Fibrillar Component

The mouse oocyte is the site of nucleolar synthesis during pachytene. The chromosomes containing a nucleolar organizer are attached to the nuclear envelope by their paracentromeric heterochromatin, either alone or by taking part in the formation of a chromocentre. The nucleolus appears at the junction of the paracentromeric heterochromatin with the euchromatic portion of the bivalent. In this zone, 5.0-nm-diameter fibres, thinner than those of the rest of the chromosome (10.0 nm), extend from the lateral element of the synaptonemal complex up to the nucleolar fibrillar centre in which they penetrate. At the onset of its synthesis, the nucleolus only contains the fibrillar centre and an electron-dense fibrillar component in continuity with the latter. Growth of the nucleolus often takes place in the form of a strand whose proximal end, in contact with the fibrillar centre, is formed by preribosomal fibrils and whose distal end is at first fibrillo-granular then granular. Following brief incorporation of tritiated uridine, nucleolar labelling is active in oogonia. No ribosomal RNA-synthetic activity is revealed during leptotene and zygotene. Incorporation resumes at mid-pachytene, with labelling located over the electron-dense fibrillar component adjacent to the fibrillar centre. These observations suggest that the rDNA is located in both the fibrillar centre and its associated electron-dense fibrillar component and that the rDNA transcription occurs in the latter.

scholarly journals Hyperspectral Three-Dimensional Fluorescence Imaging Using Snapshot Optical Tomography

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3652
Author(s):  
Cory Juntunen ◽  
Isabel M. Woller ◽  
Yongjin Sung
Keyword(s):  
Fourier Transform ◽  
3D Imaging ◽  
Optical Tomography ◽  
Three Dimensional ◽  
High Spectral Resolution ◽  
Functional Information ◽  
Fluorescent Beads ◽  
Different Depths ◽  
Projection Images ◽  
Imaging Performance

Hyperspectral three-dimensional (3D) imaging can provide both 3D structural and functional information of a specimen. The imaging throughput is typically very low due to the requirement of scanning mechanisms for different depths and wavelengths. Here we demonstrate hyperspectral 3D imaging using Snapshot projection optical tomography (SPOT) and Fourier-transform spectroscopy (FTS). SPOT allows us to instantaneously acquire the projection images corresponding to different viewing angles, while FTS allows us to perform hyperspectral imaging at high spectral resolution. Using fluorescent beads and sunflower pollens, we demonstrate the imaging performance of the developed system.

scholarly journals Imaging the Human Thyroid Using Three-Dimensional Diffuse Optical Tomography: A Preliminary Study

2021 ◽  
Vol 11 (4) ◽  
pp. 1670
Author(s):  
Tetsuya Mimura ◽  
Shinpei Okawa ◽  
Hiroshi Kawaguchi ◽  
Yukari Tanikawa ◽  
Yoko Hoshi
Keyword(s):  
Optical Tomography ◽  
Tumor Hypoxia ◽  
Three Dimensional ◽  
Diffuse Optical Tomography ◽  
Element Model ◽  
Needle Aspiration ◽  
Human Thyroid ◽  
Tissue Oxygen Saturation ◽  
Preliminary Study ◽  
First Time

Thyroid cancer is usually diagnosed by ultrasound imaging and fine-needle aspiration biopsy. However, diagnosis of follicular thyroid carcinomas (FTC) is difficult because FTC lacks nuclear atypia and a consensus on histological interpretation. Diffuse optical tomography (DOT) offers the potential to diagnose FTC because it can measure tumor hypoxia, while image reconstruction of the thyroid is still challenging mainly due to the complex anatomical features of the neck. In this study, we attempted to solve this issue by creating a finite element model of the human neck excluding the trachea (a void region). By reconstruction of the absorption coefficients at three wavelengths, 3D tissue oxygen saturation maps of the human thyroid are obtained for the first time by DOT.

Three-dimensional surface reconstruction within noncontact diffuse optical tomography using structured light

2012 ◽  
Vol 17 (12) ◽  
pp. 126009 ◽  
Author(s):  
Kirstin Baum ◽  
Raimo Hartmann ◽  
Tobias Bischoff ◽  
Jan O. Oelerich ◽  
Stephan Finkensieper ◽  
...  
Keyword(s):  
Surface Reconstruction ◽  
Structured Light ◽  
Optical Tomography ◽  
Three Dimensional ◽  
Diffuse Optical Tomography ◽  
Dimensional Surface

Acceleration of the EM-like reconstruction method for diffuse optical tomography with ordered-subsets method

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
Caifang Wang
Keyword(s):  
Numerical Experiments ◽  
Imaging Modality ◽  
Random Medium ◽  
Optical Tomography ◽  
Back Propagation ◽  
Three Dimensional ◽  
Diffuse Optical Tomography ◽  
Optical Parameters ◽  
Reconstruction Method ◽  
Boundary Measurements

Abstract.Diffuse optical tomography (DOT) is an optical imaging modality, which provides the spatial distribution of the optical parameters inside a random medium. A propagation back-propagation method named EM-like reconstruction method for stationary DOT problem has been proposed yet. This method is really time consuming. Hence the ordered-subsets (OS) technique for this reconstruction method is studied in this paper. The boundary measurements of DOT are grouped into nonoverlapping and overlapping ordered sequence of subsets with random partition, sequential partition and periodic partition, respectively. The performance of OS methods is compared with the standard EM-like reconstruction method with two-dimensional and three-dimensional numerical experiments. The numerical experiments indicate that reconstruction of nonoverlapping subsets with periodic partition, overlapping subsets with periodic partition and standard EM-like method provide very similar acceptable reconstruction results. However, reconstruction of nonoverlapping subsets with periodic partition spends a minimum of time to get proper results.

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