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 Alpha-satellite probes
(chromosome enumeration probes)
Alpha satellite DNA is composed of highly repetitive sequence
elements found near human chromosome centromeres, and in most cases is
chromosome-specific. FISH probes made of this type of DNA are mainly used
to determine aneuploidy and to identify the origin of small "marker"
chromosomes
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A dicentric marker chromosome was discovered to be derived from #14
or #22 as the results of this mixture of alpha satellites shows. The marker
is indicated by the arrow. Notice the double signal, because of the presence
of two centromeres. (See case of the month, 4/97) |
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This picture demonstrates "3-color FISH". The red signals
represent the number of copies of chromosome #6, and the green signals
chromosome #8's. The blue is just a counterstain to visualize the nucleus. |
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In this metaphase, the X chromosome is indicated
by the red signal, and the Y is green. The Y chromosome probe also contains
repetitive DNA from the end of the long arm. Notice the signals present
in the interphase cell at the lower left also. |
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 Back to main FISH page
University of Wisconsin - Madison
Waisman Center Cytogenetics Lab
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