scholarly journals MICROFLUOROMETRIC ANALYSIS OF DEOXYRIBONUCLEIC ACID REPLICATION KINETICS AND SISTER CHROMATID EXCHANGES IN HUMAN CHROMOSOMES

1974 ◽  
Vol 22 (7) ◽  
pp. 478-491 ◽  
Author(s):  
SAMUEL A. LATT
Keyword(s):  
High Resolution ◽  
Dna Synthesis ◽  
Sister Chromatid ◽  
Deoxyribonucleic Acid ◽  
Sister Chromatid Exchanges ◽  
Human Chromosomes ◽  
Metaphase Chromosomes ◽  
Banding Patterns ◽  
Human Leukocytes ◽  
Chromatid Exchanges

Fluorescence of the dye 33258 Hoechst, when bound to chromosomes, is partially quenched by the incorporation of 5-bromodeoxyuridine into chromosomal deoxyribonucleic acid (DNA). This effect allows microfluorometric analysis of DNA synthesis. Metaphase chromosomes from cultured human leukocytes which have incorporated 5-bromodeoxyuridine for a portion of the DNA synthesis period exhibit reduced 33258 Hoechst fluorescence in 5-bromodeoxyuridine-containing regions. Regions synthesizing DNA during a particular interval can thus be highlighted by the appropriate protocol of 5-bromodeoxyuridine administration. Chromosomes from cells which have replicated twice in medium containing 5-bromodeoxyuridine exhibit one brightly and one dully fluorescing chromatid, reflecting incorporation of 5-bromodeoxyuridine into one or two chains of chromatid DNA, respectively. Sister chromatid exchanges, evident as sharply demarcated reciprocal alterations in fluorescence along chromosomes, can be located relative to quinacrine banding patterns. This fluorometric approach should be useful in many instances as a convenient, high resolution alternative to autoradiography.

Possible role of DNA synthesis in formation of sister chromatid exchanges

Nature ◽  
1974 ◽  
Vol 252 (5485) ◽  
pp. 739-741 ◽  
Author(s):  
HATAO KATO
Keyword(s):  
Dna Synthesis ◽  
Sister Chromatid ◽  
Sister Chromatid Exchanges ◽  
Chromatid Exchanges

Inhibitors of DNA synthesis induce sister chromatid exchanges at the early S phase of the cell cycle

Chromosoma ◽  
1984 ◽  
Vol 90 (1) ◽  
pp. 46-49 ◽  
Author(s):  
G. Rainaldi ◽  
M. R. Sessa ◽  
T. Mariani
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Sister Chromatid ◽  
Sister Chromatid Exchanges ◽  
S Phase ◽  
Chromatid Exchanges

scholarly journals Automatic measurement of sister chromatid exchange frequency.

1977 ◽  
Vol 25 (7) ◽  
pp. 741-753 ◽  
Author(s):  
G W Zack ◽  
W E Rogers ◽  
S A Latt
Keyword(s):  
Sister Chromatid ◽  
Sister Chromatid Exchange ◽  
Detection System ◽  
Automatic Measurement ◽  
Sister Chromatid Exchanges ◽  
Metaphase Chromosomes ◽  
Exchange Frequency ◽  
Sister Chromatid Exchange Frequency ◽  
Chromatid Exchanges ◽  
Microscope Slides

An automatic system for detecting and counting sister chromatid exchanges in human chromosomes has been developed. Metaphase chromosomes from lymphocytes which had incorporated 5-bromodeoxyuridine for two replication cycles were treated with the dye 33258 Hoechst and photodegraded so that the sister chromatids exhibited differential Giemsa staining. A computer-controlled television-microscope system was used to acquire digitized metaphase spread images by direct scanning of microscope slides. Individual objects in the images were identified by a thresholding procedure. The probability that each object was a single, separate chromosome was estimated from size and shape measurements. An analysis of the spatial relationships of the dark-chromatid regions of each object yielded a set of possible exchange locations and estimated probabilities that such locations corresponded to sister chromatid exchanges. A normalized estimate of the sister chromatid exchange frequency was obtained by summing the joint probabilities that a location contained an exchange within a single, separate chromosome over the set of chromosomes from one or more cells and dividing by the expected value of the total chromosome area analyzed. Comparison with manual scoring of exchanges showed satisfactory agreement up to levels of approximately 30 sister chromatid exchanges/cell, or slightly more than twice control levels. The processing time for this automated sister chromatid exchange detection system was comparable to that of manual scoring.

scholarly journals Automatic detection and localization of sister chromatid exchanges.

1976 ◽  
Vol 24 (1) ◽  
pp. 168-177 ◽  
Author(s):  
G W Zack ◽  
J A Spriet ◽  
S A Latt ◽  
G H Granlund ◽  
I T Young
Keyword(s):  
Computer Analysis ◽  
Sister Chromatid ◽  
Automatic Detection ◽  
Sister Chromatid Exchanges ◽  
Banding Patterns ◽  
Sister Chromatids ◽  
Manual Methods ◽  
Detection And Localization ◽  
Chromatid Exchanges

Sister chromatids of human metaphase chromsomes from cells which have replicated twice in medium containing 5-bromodeoxyuridine exhibit unequal fluorescence when stained with the dye 33258 Hoechst. Sister chromatid exchanges occurring in these chromosomes are apparent as interchanges of brightly and dully fluorescing chromatids. A technique for detecting such exchanges by computer analysis of chromsome images has been developed and found to campare favorably with manual methods. The exchanges have been localized in the context of quinacrine banding patterns.

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