Heterochromatin, the synaptonemal complex and crossing over

1984 ◽  
Vol 71 (1) ◽  
pp. 159-176 ◽  
Author(s):  
S.M. Stack
Keyword(s):  
Electron Microscopy ◽  
Lycopersicon Esculentum ◽  
Synaptonemal Complex ◽  
Electron Microscopic Examination ◽  
Differential Staining ◽  
Crossing Over ◽  
Mitotic Metaphase ◽  
Plantago Ovata ◽  
Electron Microscopic ◽  
Metaphase Chromosomes

A combined light- and electron-microscopic examination of chromosomes from two angiospermous plants, Plantago ovata and Lycopersicon esculentum, and a mammal, Mus musculus, was performed. From this investigation three observations have been made that may be relevant to the observed lack of crossing over in heterochromatin. (1) Differential staining indicates that heterochromatin represents a smaller fraction of the length of pachytene chromosomes than it represents in the length of mitotic metaphase chromosomes. Since the synaptonemal complex (SC) runs throughout the length of these pachytene chromosomes, it is under-represented in heterochromatin. Considering the evidence for a rough correlation between the length of SC and the amount of crossing over, this could result in less crossing over in heterochromatin than expected on the basis of its length in mitotic metaphase chromosomes. (2) Electron microscopy indicates that, unlike the SC in euchromatin, the SC in heterochromatin is densely ensheathed in highly compact chromatin. If crossing over occurs in the SC or even in the surrounding chromatin, the compaction of the chromatin may prevent the penetration of enzymes needed in recombination. (3) Finally, a difference in the structure of SCs in euchromatin versus heterochromatin was observed that could be associated with the lack of crossing over in heterochromatin.

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.

A Comparative Study of Fractographic Replicas

1974 ◽  
Vol 32 ◽  
pp. 566-567
Author(s):  
Loren Anderson ◽  
Pat Pizzo ◽  
Glen Haydon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscopic Examination ◽  
Direct Examination ◽  
Electron Microscopic ◽  
Reliable Technique ◽  
Service Failures ◽  
Transmission Electron ◽  
Mode Of Failure ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Transmission electron microscopy of replicas has long been used to study the fracture surfaces of components which fail in service. Recently, the scanning electron microscope (SEM) has gained popularity because it allows direct examination of the fracture surface. However, the somewhat lower resolution of the SEM coupled with a restriction on the sample size has served to limit the use of this instrument in investigating in-service failures. It is the intent of this paper to show that scanning electron microscopic examination of conventional negative replicas can be a convenient and reliable technique for determining mode of failure.

A New Human Breast Tumor Cell Line

1975 ◽  
Vol 33 ◽  
pp. 388-389
Author(s):  
R.E. Nordquist ◽  
R.M. Wasik ◽  
P.J. Riggs ◽  
P.L. Munson ◽  
F.B. Schafer
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Calf Serum ◽  
Tumor Cell Line ◽  
Electron Microscopic Examination ◽  
Epithelial Cell Line ◽  
Electron Microscopic ◽  
Fixed Tissue ◽  
Excised Tissue ◽  
Caucasian Female

An infiltrating ductal cell carcinoma was removed from the breast of a postmenopausal Caucasian female. The excised tissue was divided into three parts; one part for electron microscopy, one part for tissue culture and the remainder frozen for immunological studies.The tissue for culture was minced finely with sterile razor blades and cultured in Falcon flasks containing Eagel's MEM supplemented with 10% heat denatured fetal calf serum. The tissue for electron microscopy was fixed in 6.25% glutaraldehyde in 0.1 M PO4 buffer plus 5% sucrose and postfixed in 1% OsO4 in the same buffer. The fixed tissue was dehydrated in graded ethanol and embedded in Spurr.The tissue which was cultured began to grow out after approximately six weeks and became a continuous epithelial cell line which was designated BOT-2 (Breast Original Tumor). Electron microscopic examination revealed that these cells had epithelial characteristics, i.e. the presence of tonofilaments and well formed desmosomes.

scholarly journals Infectious gastroenteritis in Norfolk Island and recovery of viruses from drinking water

1983 ◽  
Vol 91 (1) ◽  
pp. 139-146 ◽  
Author(s):  
A. M. Murphy ◽  
G. S. Grohmann ◽  
M. F. H. Sexton
Keyword(s):  
Electron Microscopy ◽  
Drinking Water ◽  
Cell Cultures ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Infectious Gastroenteritis ◽  
High Incidence ◽  
Norfolk Island ◽  
High Level

SUMMARYA high incidence of gastroenteritis in both islanders and tourists has been recorded in recent years on Norfolk Island – a popular tourist resort for Australians and New Zealanders. No bacterial cause has been found. However, electron microscopic examination of 28 faecal specimens revealed viruses associated with gastroenteritis in 21 (75%). No viruses were isolated in cell cultures. Bore water is used for drinking purposes on the island and 32 samples from 15 bores were examined for viruses by electron microscopy and culture as well as for bacterial contamination. Seven polioviruses (all type 1 vaccine strain) and adenoviruses 1 and 5 were isolated in cell cultures. In addition one rotavirus, one adenovirus and two small round viruses were detected by electron microscopy. Six of 21 samples tested showed unacceptably high levels of bacteria for drinking water. The deep ground water has apparently become contaminated with sewage effluent and is almost certainly the main cause of the high level of gastroenteritis on the island.

A comparison of the effects of several antifungal imidazole derivatives and polyenes on Candida albicans: an ultrastructural study by scanning electron microscopy

1982 ◽  
Vol 28 (10) ◽  
pp. 1119-1126 ◽  
Author(s):  
M. Bastide ◽  
S. Jouvert ◽  
J.-M. Bastide
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Candida Albicans ◽  
Cytoplasmic Membrane ◽  
Electron Microscopic Examination ◽  
Yeast Cells ◽  
Electron Microscopic ◽  
Imidazole Derivatives ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

The early events in the interaction of two polyene (amphotericin B and nystatin) and five imidazole (clotrimazole, ketoconazole, miconazole, isoconazole, and econazole) antimycotics used at fungicidal concentrations with the surface of Candida albicans were studied by scanning electron microscopic examination of treated intact young yeast cells, treated spheroplasts, and spheroplasts liberated from treated young yeast cells. In all cases, treatment lasted 2 h. The polyenes passed through the yeast cell wall and interacted with the cytoplasmic membrane causing the spheroplasts to lose their characteristic spheric form and to liberate their contents. Clotrimazole caused the formation of numerous circular openings in the cytoplasmic membrane, but only when the agent was used to treat spheroplasts directly. Ketoconazole, miconazole, isoconazole, and econazole interacted with the cell wall causing formation of convolutions and wrinkles. The three imidazole derivatives that are structurally closely related, miconazole, isoconazole, and econazole, inhibited the enzyme-catalyzed release of spheroplasts from young yeast cells.

The Evaluation of Ciliary Function: Electron versus Light Microscopy

1998 ◽  
Vol 12 (3) ◽  
pp. 199-202 ◽  
Author(s):  
Stephen B. Kupferberg ◽  
John P. Bent ◽  
Edward S. Porubsky
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Primary Ciliary Dyskinesia ◽  
Imaging Techniques ◽  
Electron Microscopic Examination ◽  
Definitive Diagnosis ◽  
Electron Microscopic ◽  
Ciliary Function ◽  
Physical Findings ◽  
Ciliary Dyskinesia

Diagnosing Primary Ciliary Dyskinesia can often be difficult. Physical findings suggest the disease, but definitive diagnosis should be made with a ciliary biopsy. Twenty biopsies were obtained from 16 patients and all underwent both light and electron microscopic examination. In 8/20 (40%) there was a discrepancy between the different imaging techniques. Therefore, light microscopy should be used to assess adequacy of biopsy and motion of the cilia along with electron microscopy to examine ultrastructure.

The desynaptic mutant of maize as a combined defect of synaptonemal complex and chiasma maintenance

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 879-887 ◽  
Author(s):  
M. P. Maguire ◽  
A. M. Paredes ◽  
R. W. Riess
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
Central Region ◽  
Meiotic Prophase ◽  
Heterochromatic Region ◽  
Crossing Over ◽  
Related Strain ◽  
Normal Cells ◽  
Normal Crossing ◽  
Mutant Cells

The phenotype of the desynaptic (dy) mutant of maize in microsporocytes at meiotic prophase was compared with normal microsporocytes of a closely related strain and with microsporocytes of a maize inbred line (KYS) assumed to be normal. Strikingly more univalents and open arms of bivalents were found in the mutant cells than in normal cells at diakinesis, and where there was heterozygosity for a distal knob (heterochromatic region), separation was usually equational, indicating the occurrence of normal crossing-over followed by failure of chiasma maintenance in the mutant. Differences found in the mutant by electron microscopy were a statistically significant wider dimension of the synaptonemal complex central region and also less twisting of synapsed configurations at pachytene. It is suggested that these are side-effect symptoms of a defect in the synaptonemal complex (or associated substance), which is expressed later as sporadic loss of chiasma maintenance.Key words: desynaptic, chiasma maintenance, synaptonemal complex.

Poly(ADP-ribosyl)ation of chromatin: kinetics of relaxation and its effect on chromatin solubility

1985 ◽  
Vol 63 (7) ◽  
pp. 764-773 ◽  
Author(s):  
André Frechette ◽  
Ann Huletsky ◽  
Rémy J. Aubin ◽  
Gilbert de Murcia ◽  
Paul Mandel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Enzyme Activity ◽  
Chromatin Structure ◽  
Microscopic Examination ◽  
Electron Microscopic Examination ◽  
Histone H1 ◽  
Electrophoretic Separation ◽  
Electron Microscopic ◽  
Kinetics Of ◽  
Modified Forms

We have studied the kinetics of relaxation of poly(ADP-ribosyl)ated polynucleosomes produced by endogenous enzyme activity by comparing the generation of hyper(ADP-ribosyl)ated histone H1 and its effect on the chromatin structure as revealed by electron microscopy. A correlation can be established between the appearance of histone H1 modified forms and the localized relaxation of the chromatin. We have also noticed, in parallel, that poly(ADP-ribosyl)ated chromatin showed increased solubility in the presence of Mg2+ and 0.2 M NaCl. Electron microscopic examination of the solubilized chromatin produced by poly(ADP-ribosyl)ation shows polynucleosomes exhibiting more relaxed conformation, whereas an increasing amount of hyper(ADP-ribosyl)ated histone H1 is found in the pellet, as shown by acid–urea–polyacrylamide electrophoretic separation of histone extracts.

scholarly journals Using of the method of electron microscopy for the identification and analysis of clinically implicit pathogenetic manifestations

2018 ◽  
Vol 7 (3) ◽  
pp. 113-116
Author(s):  
L. G. Nikonova ◽  
V. V. Banin ◽  
I. G. Stel'nikova
Keyword(s):  
Diabetes Mellitus ◽  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
B Cells ◽  
Secretory Granules ◽  
Electron Microscopic Examination ◽  
The Body ◽  
Electron Microscopic ◽  
Latent Form ◽  
Insulin Cells

Electron microscopic examination of B cells of pancreatic islets of the pancreas in dogs with normal (n=10) and impaired glucose tolerance (n=10) was performed. Ultrastructural features of the organization of insulin cells associated with an increased requirement of the hormone in the body with the latent form of diabetes mellitus are established. In B cells, signs of functional tension due to unregulated secretion, manifested by the expansion of endoplasmic reticulum cisterns, Golgi complex hypertrophy, an increase in the number of immature secretory granules and vacuoles in the cytoplasm are revealed in B cells.

Electron Microscopic Observations of Purified Oat Phytochrome

1971 ◽  
Vol 29 ◽  
pp. 362-363
Author(s):  
J. T. Stasny ◽  
F. E. Mumford
Keyword(s):  
Electron Microscopy ◽  
Ammonium Sulphate ◽  
Microscopic Examination ◽  
Protein Concentration ◽  
Electron Microscopic Examination ◽  
Distilled Water ◽  
Phytochrome A ◽  
Electron Microscopic ◽  
Isolation And Purification ◽  
Molecular Dimensions

The following describes the gross morphology of purified oat phytochrome, as examined by negative staining for electron microscopy. Phytochrome, a chromoprotein important in plant photomorphogenesis, has two photoconvertible forms: PR, absorbing maximally at 664 nm and PFR at 724 nm. Although the isolation and purification of this photoreceptor has been achieved in several laboratories, its molecular dimensions have not been adequately characterized.Phytochrome was extracted from etiolated oat seedlings and purified by a previously published method. The purified oat phytochrome was prepared for electron microscopic examination by precipitation at 50 percent saturation with ammonium sulphate, followed by centrifugation at 30,000xg for 20 minutes. The resulting pellet was dissolved in twice-distilled water to give a protein concentration of approximately 200 ug/ml and then dialyzed against 1000X its volume of distilled water for 18 hours at 4°C.

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