Light and electron microscope observations of a meiotic mutant of Neurospora crassa

1978 ◽  
Vol 56 (21) ◽  
pp. 2694-2706 ◽  
Author(s):  
B.C. Lu ◽  
Donna R. Galeazzi
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Genetic Analysis ◽  
Neurospora Crassa ◽  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Light And Electron Microscopy ◽  
Homologous Chromosomes ◽  
Synaptonemal Complexes ◽  
Nuclear Separation

Light and electron microscopy have revealed that the meiotic-1 (mei-1) mutant of Neurospora crassa is defective in chromosome pairing (asynaptic) although plenty of axial components of the synaptonemal complex are produced and occasional tripartite synaptonemal complexes can be formed. The mei-1 mutant is most probably defective in bringing the homologous chromosomes together for pairing and for assembly of the synaptonemal complex. The mei-1 mutant is also defective in nuclear separation which leads to a four-poled spindle at the subsequent division. The lack of chromosome pairing, the incomplete assembly of the synaptonemal complex, and the four-poled spindles account for absence of recombination and for the nondisjunction found in genetic analysis.

A TECHNIQUE FOR LIGHT AND ELECTRON MICROSCOPY OF THE SYNAPTONEMAL COMPLEX OF THE MOUSE OOCYTE

1982 ◽  
Vol 24 (6) ◽  
pp. 675-680 ◽  
Author(s):  
Weng Kong Sung ◽  
Georgiana Jagiello
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
Microscopic Examination ◽  
Light And Electron Microscopy ◽  
Electron Microscopic Examination ◽  
Mouse Oocyte ◽  
Electron Microscopic ◽  
Synaptonemal Complexes

A method is described for obtaining synaptonemal complex preparations from mouse pachytene oocytes for light and electron microscopic examination. A karyotype based on the whole complement of synaptonemal complexes of a pachytene oocyte as visualized by electron microscopy is presented.

Ultrastructure of primary spermatocyte in fish (Tilapia: Oreochromis niloticus): The synaptonemal complex

1986 ◽  
Vol 44 ◽  
pp. 288-289
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Oreochromis Niloticus ◽  
Short Communication ◽  
Primary Spermatocyte ◽  
Mitotic Division ◽  
Meiotic Cell ◽  
Electron Microscope Level ◽  
Homologous Chromosomes

The Primary Spermatocytes represent a stage in spermatogenesis when the first meiotic cell division occurs. They are derived from Spermatogonium or Stem cell through mitotic division. At the zygotene phase of meiotic prophase the Synaptonemal complex appears in these cells in the space between the paired homologous chromosomes. Spermatogenesis and sperm structure in fish have been studied at the electron microscope level in a few species? However, no work has yet been reported on ultrastructure of tilapia, O. niloticus, spermatozoa and spermatogenetic process. In this short communication we are reporting the Ultrastructure of Primary Spermatocytes in tilapia, O. niloticus, and the fine structure of synaptonemal complexes seen in the spermatocyte nuclei.

scholarly journals Lateral Elements Inside Synaptonemal Complex-Like Polycomplexes in ndt80 Mutants of Yeast Bind DNA

Genetics ◽  
2003 ◽  
Vol 163 (2) ◽  
pp. 539-544 ◽  
Author(s):  
Hasanuzzaman Bhuiyan ◽  
Gunilla Dahlfors ◽  
Karin Schmekel
Keyword(s):  
In Situ Hybridization ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Immunoelectron Microscopy ◽  
Meiotic Prophase ◽  
Lateral Element ◽  
Homologous Chromosomes ◽  
Meiotic Prophase I ◽  
Dna Antibodies

Abstract The synaptonemal complex (SC) keeps the synapsed homologous chromosomes together during pachytene in meiotic prophase I. Structures that resemble stacks of SCs, polycomplexes, are sometimes found before or after pachytene. We have investigated ndt80 mutants of yeast, which arrest in pachytene. SCs appear normal in spread chromosome preparations, but are only occasionally found in intact nuclei examined in the electron microscope. Instead, large polycomplexes occur in almost every ndt80 mutant nucleus. Immunoelectron microscopy using DNA antibodies show strong preferential labeling to the lateral element parts of the polycomplexes. In situ hybridization using chromosome-specific probes confirms that the chromosomes in ndt80 mutants are paired and attached to the SCs. Our results suggest that polycomplexes can be involved in binding of chromosomes and possibly also in synapsis.

scholarly journals An Electron Microscope Study of Basophile Substances of Frozen-Dried Rat Liver

1958 ◽  
Vol 4 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Henry Finck
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Rat Liver ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Freeze Drying ◽  
Light And Electron Microscopy ◽  
Enzyme Treatment ◽  
Dense Granules ◽  
Homogeneous Matrix

Small pieces of liver from rats subjected to different dietary regimes were fixed by freeze-drying, and postfixed by in vacuo heating and denaturation with alcohol. Specimens were digested with ribo- or deoxyribonuclease, and stained with gallocyanin-chromalum, azure II, the Feulgen procedure or alcoholic platinic tetrabromide. Some specimens were reserved as controls of the effects of enzyme treatment. Stained and unstained specimens were embedded in methacrylate and examined by light and electron microscopy. Basophilic and Feulgen-positive substances, after contact with watery reagents, were found by electron microscopy to exist as small dense granules embedded in a less dense homogeneous matrix, forming the walls of submicroscopic vacuoles. These granules were absent after digestion with nucleodepolymerases. In specimens (unstained, or stained with platinic tetrabromide) which had not passed through water, the dense (basophile) substances in nuclei and cytoplasm were found to exist, not as granules, but as ill defined submicroscopic concentrates which blended imperceptibly into the homogeneous matrix of the vacuolar walls. Objections to the use of stains for improving contrast conditions in electron microscopy of tissues are discussed, and it is concluded that the reagents do not necessarily produce the observed increases in contrast by selectively stabilizing certain structures. The concept of microsomes as pre-existing distinct morphological entities in intact (unhomogenized) cells is thought to be inconsistent with the distribution of basophile substances in frozen-dried liver.

Mouse ovarian tissue vitrification on copper electron microscope grids versus slow freezing: a comparative ultrastructural study

2015 ◽  
Vol 27 (7) ◽  
pp. 1020 ◽  
Author(s):  
Ferda Topal-Celikkan ◽  
Sinan Ozkavukcu ◽  
Deniz Balci ◽  
Sibel Serin-Kilicoglu ◽  
Esra Atabenli-Erdemli
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Cancer Therapy ◽  
Ovarian Tissue ◽  
Light And Electron Microscopy ◽  
Slow Freezing ◽  
Ovarian Tissue Cryopreservation ◽  
Control Group ◽  
Primordial Follicles ◽  
User Friendly

There are many reasons, including cancer therapy, for premature ovarian failure and infertility. Oocyte, embryo and ovarian cryopreservation are current options for fertility preservation. Ovarian tissue cryopreservation is essential in patients whose cancer therapy cannot be delayed, including prepubertal girls, and is mostly performed using slow freezing. In the present study, mouse ovarian tissues were vitrified on copper electron microscope grids (n = 18) or conventionally slow frozen (n = 18). Post-thaw tissues were examined histologically using light and electron microscopy and compared with the control group. According to light microscopy observations, antral follicles were found to be better preserved with the slow freezing technique rather than vitrification. Electron microscopy revealed swollen mitochondria in the oocyte cytoplasm, condensations in the zona pellucida, breakages in the junctions of granulosa cells and vacuolisation in the extracellular space in pathologic follicles, which were relatively more frequent, in the vitrification group after thawing. These results indicate that ovarian slow freezing is preferable than vitrification on copper electron microscope grids, especially for larger follicles. Conversely, vitrification of ovarian pieces using cooper grids is user-friendly and provided good protection for primordial follicles and stromal cells. There is a need for further studies into advanced tissue vitrification techniques and carriers.

A method for the sequential study of synaptonemal complexes by light and electron microscopy

1981 ◽  
Vol 59 (4) ◽  
pp. 419-421 ◽  
Author(s):  
J. Navarro ◽  
F. Vidal ◽  
M. Guitart ◽  
J. Egozcue
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Synaptonemal Complexes ◽  
Sequential Study

scholarly journals ZYP1 is required for obligate cross-over formation and cross-over interference in Arabidopsis

2021 ◽  
Vol 118 (14) ◽  
pp. e2021671118
Author(s):  
Martin G. France ◽  
Janina Enderle ◽  
Sarah Röhrig ◽  
Holger Puchta ◽  
F. Chris H. Franklin ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Synaptonemal Complex ◽  
Class Ii ◽  
Class I ◽  
Crossing Over ◽  
Wild Type ◽  
Homologous Chromosomes ◽  
Virtual Absence ◽  
Meiotic Progression ◽  
Null Mutants

The synaptonemal complex is a tripartite proteinaceous ultrastructure that forms between homologous chromosomes during prophase I of meiosis in the majority of eukaryotes. It is characterized by the coordinated installation of transverse filament proteins between two lateral elements and is required for wild-type levels of crossing over and meiotic progression. We have generated null mutants of the duplicated Arabidopsis transverse filament genes zyp1a and zyp1b using a combination of T-DNA insertional mutants and targeted CRISPR/Cas mutagenesis. Cytological and genetic analysis of the zyp1 null mutants reveals loss of the obligate chiasma, an increase in recombination map length by 1.3- to 1.7-fold and a virtual absence of cross-over (CO) interference, determined by a significant increase in the number of double COs. At diplotene, the numbers of HEI10 foci, a marker for Class I interference-sensitive COs, are twofold greater in the zyp1 mutant compared to wild type. The increase in recombination in zyp1 does not appear to be due to the Class II interference-insensitive COs as chiasmata were reduced by ∼52% in msh5/zyp1 compared to msh5. These data suggest that ZYP1 limits the formation of closely spaced Class I COs in Arabidopsis. Our data indicate that installation of ZYP1 occurs at ASY1-labeled axial bridges and that loss of the protein disrupts progressive coalignment of the chromosome axes.

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.

Vacuolar ATPase of Neurospora crassa: electron microscopy, gene characterization and gene inactivation/mutation.

1992 ◽  
Vol 172 (1) ◽  
pp. 57-66
Author(s):  
B J Bowman ◽  
W J Dschida ◽  
E J Bowman
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Neurospora Crassa ◽  
Specific Inhibitor ◽  
Vacuolar Atpase ◽  
Gene Inactivation ◽  
Bafilomycin A1 ◽  
Gene Characterization ◽  
Atpase Gene ◽  
Genes Encoding

We are using three approaches to investigate the vacuolar ATPase, V-ATPase, from Neurospora crassa. (1) Examination in the electron microscope shows the enzyme has a 'ball and stalk' structure like the F-type ATPases. However, the vacuolar ATPase is significantly larger, has a prominent cleft in the head sector, and has extra components associated with the stalk and membrane sectors. (2) Genes encoding three of the major subunits of the vacuolar ATPase and the homologous subunits of the mitochondrial F-ATPase have been isolated. The exon/intron structures of the genes have been analyzed and the chromosomal locations have been determined. Two of the vacuolar ATPase genes map very close to each other, suggesting the possibility of a cluster of ATPase genes. (3) The function of the ATPase is being investigated by isolating strains with altered or inactivated ATPase. We are characterizing strains that are resistant to bafilomycin A1, a potent and specific inhibitor of the vacuolar ATPase. Initial attempts to inactivate a vacuolar ATPase gene indicate that the enzyme may be essential for growth.

XVIII.—The Spermatozoon of the Spider BeetlePtinus tectusBoieldieu as seen by Light and Electron Microscopy

1951 ◽  
Vol 64 (3) ◽  
pp. 353-366 ◽  
Author(s):  
Jozef Dlugosz ◽  
John W. Harrold
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscope ◽  
Light And Electron Microscopy ◽  
Sperm Head ◽  
Central Axis

SynopsisThe mature Ptinid sperm examined under the light microscope is found to be specialised in that the chromatin is not contained within a sperm head but is distributed along a central axis. The migration of chromatin resembles that found in Coccids by Hughes-Schrader (1948). Surrounding the axis is a more flexible helical membrane extending the whole length of the sperm.Under the electron microscope the membrane appears to consist of eighteen or twenty thin fibres and two thick fibres with striated sheaths. Near the posterior end of the membrane the fibres are surrounded by a ring. The structure is simpler than that of mammalian and avian sperms examined by other workers with similar techniques. Under the electron microscope, stages in the migration of chromatin in the immature sperm show a number of discrete opaque bodies which may be chromosomes. The approximate dimensions of the various structures are given.

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