An ultrastructural pachytene karyotype for Puccinia graminis f.sp. tritici

1992 ◽  
Vol 70 (2) ◽  
pp. 401-413 ◽  
Author(s):  
E. W. A. Boehm ◽  
J. C. Wenstrom ◽  
D. J. McLaughlin ◽  
L. J. Szabo ◽  
A. P. Roelfs ◽  
...  
Keyword(s):  
Key Words ◽  
Synaptonemal Complex ◽  
Electron Micrographs ◽  
Three Dimensional ◽  
Chromosome Length ◽  
Epifluorescence Microscopy ◽  
Puccinia Graminis ◽  
Morphological Markers ◽  
Dimensional Reconstruction ◽  
Pachytene Karyotype

The karyotype for Puccinia graminis f.sp. tritici was determined from reconstructions of electron micrographs of serially sectioned pachytene nuclei. Epifluorescence microscopy was used to select DAPI-stained, pachytene nuclei in teliospore protoplasts from which walls were mechanically removed. Selection increased the probability that pachytene nuclei could be found in the absence of morphological markers. Six pachytene nuclei were reconstructed from four geographically disparate North American isolates. One nucleus was used to obtain a computer-enhanced, three-dimensional reconstruction that could be rendered as rotatable colorized stereo pairs. A karyotype of n = 18 was determined for all six nuclei. The 18 bivalents varied only slightly in size, each ranging from 3.0 to 8.8% of the total length of the genome. Total genomic lengths also proved highly comparable among isolates. Centromeres were not found, precluding use of the centromeric index as an aid in karyotyping. Only the nucleolus-associated bivalent could be cross-correlated among the six reconstructed nuclei. Heterogeneity in length among, but not within, isolates was observed for this bivalent, suggesting that chromosome length may be polymorphic in P. graminis f.sp. tritici, despite a constant total number of chromosomes. Key words: chromosomes, heterobasidiomycete, synaptonemal complex, Uredinales.

The synaptonemal complexes of Achlya recurva (Oomycetes): karyotype analysis and three-dimensional reconstruction of pachytene nuclei in antheridia and oogonia

1991 ◽  
Vol 69 (6) ◽  
pp. 1384-1395 ◽  
Author(s):  
Hobart R. Williamson ◽  
Pesach Ben Yitzchak
Keyword(s):  
Synaptonemal Complex ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolus Organizer Region ◽  
Three Dimensional ◽  
Central Element ◽  
Three Dimensional Reconstruction ◽  
Synaptonemal Complexes ◽  
Sequence Of Events ◽  
Dimensional Reconstruction

Fifteen synaptonemal complexes, as determined by three-dimensional reconstruction of serial, ultrathin sections, were present within both antheridial and oogonial zygotene and pachytene nuclei of the oomyceteous fungus Achlya recurva, thus n = 15. The present study represents the first complete reconstruction of synaptonemal complexes in the genus Achlya. The occurrence of both zygonema and pachynema was simultaneous in antheridia and oogonia. Pachytene nuclei of antheridia and oogonia are small, 13 μm3 in volume, and the average length of the synaptonemal complexes ranged from 1.9 to 4.4 μm. Lateral elements at zygotene ranged from 1.2 to 4.7 μm. Both ends of each synaptonemal complex were attached randomly to the nuclear envelope, so a bouquet formation was not observed at pachytene. In A. recurva, the dimensions of the synaptonemal complex were as follows: overall width = 270 nm; the lateral elements = 75 nm each in width and the central region = 120 nm. There was no central element and associated transverse filaments, which may be associated with development of alternative reproductive strategies other than amphimixis, as in nematodes. Of the 15 synaptonemal complexes present, only the one carrying the nucleolus organizer region could be clearly identified from one nucleus to the next. The nucleolar organizer region was on the average 0.75 μm from the telomere in both zygotene and pachytene nuclei. There were an average of three recombination nodules in each nucleus. Synaptonemal complexes have been reported in over 80 different species of fungi and related protista. Karyotypic evolution in the oomycetes and fungi may be the result of poly-ploidization, followed by cytogenetic diversification involving aneuploidy and differing degrees of polyploidy. Such a sequence of events could explain the apparent polyphyletic formation of this group. Key words: karyotype, Oomycetes, pachytene, synaptonemal complexes, three-dimensional reconstruction.

scholarly journals THE THREE-DIMENSIONAL RECONSTRUCTION OF THE XY CHROMOSOMAL PAIR IN HUMAN SPERMATOCYTES

1970 ◽  
Vol 45 (1) ◽  
pp. 43-53 ◽  
Author(s):  
A. J. Solari ◽  
Laura L. Tres
Keyword(s):  
Synaptonemal Complex ◽  
Three Dimensional ◽  
Strong Support ◽  
Serial Sections ◽  
Lateral Element ◽  
Spatial Reconstruction ◽  
Chromosomal Pair ◽  
Dimensional Reconstruction ◽  
Short Core ◽  
Apparent Association

The spatial reconstruction of the XY pair of chromosomes from human spermatocytes has been made by the study of serial sections 1000 A in thickness. The sex pair during zygotene-pachytene forms a condensed mass of chromatin that has two filamentous, electron-opaque cores: the long and the short core. During early pachytene both cores have a common ending region, about 0.4–0.8 µ long. This common end is a synaptonemal complex, and each of the cores forms a lateral element of that complex. The cores become more convoluted during middle pachytene forming "ringlike bodies." Nucleoli from spermatocytes have three distinct regions: (a) granular; (b) dense fibrillar; and (c) clear intermediate. Occasional association of the XY pair and the heteropycnotic "basal knobs" results in apparent association of nucleoli and the sex pair in a minority of cells. The evidence presented is interpreted as a strong support of the hypothesis of homologous regions in the human XY pair.

Three-dimensional reconstruction of a human metaphase chromosome from electron micrographs

Chromosoma ◽  
1987 ◽  
Vol 95 (5) ◽  
pp. 366-374 ◽  
Author(s):  
George Harauz ◽  
Lisa Borland ◽  
Gunter F. Bahr ◽  
Elmar Zeitler ◽  
Marin van Heel
Keyword(s):  
Electron Micrographs ◽  
Metaphase Chromosome ◽  
Three Dimensional ◽  
Three Dimensional Reconstruction ◽  
Dimensional Reconstruction

Three-dimensional structure analysis of melanocytes and keratinocytes in senile lentigo

Microscopy ◽  
2020 ◽  
Author(s):  
Yuki Mizutani ◽  
Mika Yamashita ◽  
Rie Hashimoto ◽  
Toru Atsugi ◽  
Akemi Ryu ◽  
...  
Keyword(s):  
Electron Micrographs ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Normal Skin ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Confocal Laser ◽  
Scanning Electron Micrographs ◽  
Large Numbers ◽  
Dimensional Reconstruction

Abstract Senile lentigo or age spots are hyperpigmented macules of skin that commonly develop following long-term exposure to ultraviolet radiation. This condition is caused by accumulation of large numbers of melanosomes (melanin granules) produced by melanocytes within neighboring keratinocytes. However, there is still no consensus regarding the melanosome transfer mechanism in senile lentigo. To date, most pathohistological studies of skin have been two-dimensional and do not provide detailed data on the complex interactions of the melanocyte–keratinocyte network involved in melanosome transfer. We performed a three-dimensional reconstruction of the epidermal microstructure in senile lentigo using three different microscopic modalities to visualize the topological melanocyte–keratinocyte relationship and melanosome distribution. Confocal laser microscopy images showed that melanocyte dendritic processes are more frequently branched and elongated in senile lentigo skin than in normal skin. Serial transmission electron micrographs showed that dendritic processes extend into intercellular spaces between keratinocytes. Focused ion beam-scanning electron micrographs showed that dendritic processes in senile lentigo encircle adjacent keratinocytes and accumulate large numbers of melanosomes. Moreover, melanosomes transferred to keratinocytes are present not only in the supranuclear area but throughout the perinuclear area except on the basal side. The use of these different microscopic methods helped to elucidate the three-dimensional morphology and topology of melanocytes and keratinocytes in senile lentigo. We show that the localization of melanosomes in dendritic processes to the region encircling recipient keratinocytes contributes to efficient melanosome transfer in senile lentigo.

Three-Dimensional reconstruction of the synaptonemal complex from high-pressure frozen maize meiocytes using IVEM Tomography

1994 ◽  
Vol 52 ◽  
pp. 14-15
Author(s):  
Jennifer C. Fung ◽  
David A. Agard ◽  
John W. Sedat
Keyword(s):  
Synaptonemal Complex ◽  
Three Dimensional ◽  
Central Element ◽  
Homologous Chromosomes ◽  
Macromolecular Assembly ◽  
Dimensional Reconstruction ◽  
Protein Components ◽  
Basic Features ◽  
General Architecture ◽  
Internal Architecture

The synaptonemal complex (SC) is a key macromolecular assembly formed during meiosis of most eukaryotes. It has a crucial role in maintaining synapsis between homologous chromosomes and in ensuring proper segregation of the homologs through the establishment of functional chiasmata. Recently, biochemical and genetic efforts have begun to identify some of the protein components of the SC. As these efforts progress, a more detailed analysis of SC structure will also be needed to incorporate these new components into the overall organization of the SC.Early efforts into the analysis of SC structure have established that its general architecture is conserved throughout many organisms. The basic features found in every SC are the two lateral elements and the central element, both which run longitudinally between the homologs during the pachytene stage of prophase I. Transverse elements which run perpendicular to the homolog axis through the central region are also often found. Although the general features of the SC are conserved, the internal architecture of these components can differ.

Three-Dimensional reconstruction of the synaptonemal complex from pachytene maize meiocytes using Electron Microscopy tomography

1993 ◽  
Vol 51 ◽  
pp. 182-183
Author(s):  
Jennifer C. Fung ◽  
Bethe A. Scalettar ◽  
David A. Agard ◽  
John W. Sedat
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
Chromosome Segregation ◽  
Three Dimensional ◽  
Central Element ◽  
Amorphous Structure ◽  
Two Dimensional ◽  
Homologous Chromosomes ◽  
Exact Function ◽  
Dimensional Reconstruction

The synaptonemal complex (SC) is a structure involved in the synapsis of homologous chromosomes during the prophase I stage of meiosis. Although the exact function of the complex is unknown, it has been suggested that one possible role might be to promote recombination by ensuring close synapsis of the homologous chromosomes. In addition, it is thought that the SC may also be required to convert the resulting recombination events into functional chiasmata to provide for proper chromosome segregation at the end of the first stage of meiosis.The SC structure itself is highly conserved across a variety of species. The organization of the SC is tripartite consisting of lateral, central and transverse elements. Two-dimensional cytological observations have been made to characterize the general features of these SC components. The lateral elements are 300 - 500 Å wide proteinaceous structures which flank the synapsed regions of the chromosome bivalent. Between the two lateral elements is a central region containing the central element commonly characterized as a less dense amorphous structure.

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