scholarly journals THE EFFECT OF PREFIXATION ON THE DIAMETER OF CHROMOSOME FIBERS ISOLATED BY THE LANGMUIR TROUGH-CRITICAL POINT METHOD

1968 ◽  
Vol 37 (3) ◽  
pp. 610-620 ◽  
Author(s):  
Stephen L. Wolfe
Keyword(s):  
Critical Point ◽  
Average Diameter ◽  
Point Method ◽  
Root Tip ◽  
Langmuir Trough

The effect of prefixation on the diameter of chromosome fibers isolated by the Langmuir trough-critical point method has been investigated in several species of plants and animals. In barley, fibers isolated from endosperm without prefixation have an average diameter of between 240 and 250 A, and are similar in dimensions and structure to the chromosome fibers isolated from animals by this method. Chromosome fibers from other tissues of the same plant are smaller in diameter when isolated without prefixation, approximating 200 A. After prefixation in 2% buffered formalin, isolated fibers from the three barley tissues studied are reduced in diameter, to approximately 120–130 A for endosperm and leaflet and to 140 A for root tip. Chromosome fibers isolated from newt erythrocytes also show a significantly reduced diameter after formalin prefixation, to approximately 120 A.

scholarly journals THE STRANDEDNESS OF MEIOTIC CHROMOSOMES FROM ONCOPELTUS

1966 ◽  
Vol 31 (1) ◽  
pp. 31-42 ◽  
Author(s):  
Stephen L. Wolfe ◽  
Godfrey M. Hewitt
Keyword(s):  
Electron Microscope ◽  
Critical Point ◽  
Living Cells ◽  
Point Method ◽  
Oncopeltus Fasciatus ◽  
Langmuir Trough ◽  
Ringer’S Solution ◽  
Meiotic Chromosomes ◽  
Parallel Folding

Meiotic chromosomes were isolated from male Oncopeltus fasciatus by dissecting the testes under insect Ringer's solution and spreading the living cells on the Langmuir trough. After being dried by the critical point method, preparations were examined under the electron microscope. Chromosomes at all stages of prophase prove to be multistranded. A significant increase in the number of parallel 250 A fibers in the chromosomes occurs between zygotene and diakinesis. Parallel folding, rather than true multistrandedness, is interpreted as the mechanism responsible for this observed increase in multistrandedness. It has not been possible to determine whether the multistrandedness observed at leptotene represents true multistrandedness or is the result of parallel folding. Apparent multistrandedness is lost at metaphase when the 250 A fibers of the chromosomes become coiled more tightly. In preparations isolated by these methods, no structures other than the 250 A chromosome fibers are visible in the chromomeres, which appear as regionally coiled or folded areas of the fibers along the arm of the chromosome.

Scanning Electron Microscopy of Dried and Acid Treated Shells of Difflugia

1973 ◽  
Vol 31 ◽  
pp. 448-449
Author(s):  
Barry S. Eckert ◽  
S. M. McGee-Russell
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Critical Point ◽  
Point Method ◽  
External Structure ◽  
Cell Locomotion ◽  
Single Opening ◽  
Scanning Electron

Difflugia lobostoma is a shelled amoeba. The shell is an external structure of considerable mass which presents the animal with special restrictions in cell locomotion which are met by the development of active pseudopodial lobopodia containing, apparently, an organized system of thick and thin microfilaments (Eckert and McGee-Russell, 1972). The shell is constructed of sand grains picked up from the environment, and cemented into place with a secretion. There is a single opening through which lobopods extend. The organization of the shell was studied by scanning electron microscopy (SEM).Intact shells or animals with shells were dried by the critical point method of Anderson (1966) or air dried, after primary fixation in glutaraldehyde.

A multiaxial criterion for notch high-cycle fatigue using a critical-point method

2008 ◽  
Vol 75 (7) ◽  
pp. 1864-1874 ◽  
Author(s):  
Andrea Carpinteri ◽  
Andrea Spagnoli ◽  
Sabrina Vantadori ◽  
Danilo Viappiani
Keyword(s):  
Critical Point ◽  
High Cycle Fatigue ◽  
Point Method ◽  
Cycle Fatigue

scholarly journals THE HUMAN CHROMOSOME

1969 ◽  
Vol 41 (1) ◽  
pp. 73-90 ◽  
Author(s):  
J. G. Abuelo ◽  
Dorothy E. Moore
Keyword(s):  
Tissue Culture ◽  
Electron Microscope ◽  
Human Chromosome ◽  
Critical Point ◽  
Human Lymphocytes ◽  
Langmuir Trough ◽  
Trypsin Treatment ◽  
Short Term ◽  
Dnase Digestion ◽  
Critical Point Drying

Human lymphocytes were grown in short-term tissue culture and were arrested in metaphase with Colcemid. Their chromosomes were prepared by the Langmuir trough-critical point drying technique and were examined under the electron microscope. In addition, some chromosomes were digested with trypsin, Pronase, or DNase. The chromosomes consist entirely of tightly packed, 240 ± 50-A chromatin fibers. Trypsin and Pronase treatments induce relaxation of fiber packing and reveal certain underlying fiber arrangements. Furthermore, trypsin treatment demonstrates that the chromatin fiber has a 25–50 A trypsin-resistant core surrounded by a trypsin-sensitive sheath. DNase digestion suggests that this core contains DNA.

Comparison of the Second-derivative Critical-point Method with Fourier Analysis for Noise Removal

2014 ◽  
Vol 64 (10) ◽  
pp. 963-967
Author(s):  
Han Gyeol PARK ◽  
Tae Jung KIM* ◽  
Jun Seok BYUN ◽  
Yu Ri KANG ◽  
Young Dong KIM†
Keyword(s):  
Fourier Analysis ◽  
Critical Point ◽  
Noise Removal ◽  
Point Method ◽  
Second Derivative
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