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Microsatellites and minisatellites

Joseph C. Bagshaw jbagshaw at wpi.WPI.EDU
Thu Jul 7 07:44:02 EST 1994

Bixing Huang recently asked about the difference between microsatellites
and minisatellites.  I don't claim to be the authority, but since
there has been only one brief response I'll toss in my TCW, based
on what I've read.

As the one response stated, the first difference is size.  Micro-
satellites, aka simple sequence repeats, are repeatas of only a
few bases, like two or three or five.  The number of repeats in a
cluster is variable, thus the variable number of tandem repeats
(VNTR) characteristic that is usefull in gene mapping and is now
implicated in a growing number of genetic diseases.  A "clasic"
example of a microsatellite is the apparently ubiquitous CACA
sequence.  Even shrimp are full of CACA.

Minisatellites are larger, usually from a hundred or so bp up to 
several hundred.  They are sometimes found in tandem arrays, but 
more often are scattered around the genome.  The human et al. 
Alu sequence, and the Jeffreys sequences used in forensic DNA
fingerprinting are good examples.  

Sometimes the difference between micor and mini gets fuzzy. 
For example, how would you characterize the following:

   A tandemly repeated structure consisting of about 130
   bp, fairly constant in sequence, separated by variable
   numbers of a 5 bp repeat?

   A dispersed structure of about 80 bp, consisting of a
   conglomerate of 2 and 3 bp repeats?

Trivia question:  Why are satellite DNAs so named?  Be careful,
if you know the answer, you may reveal your age.
********************  HAVE GENES, WILL TRAVEL  ********************
Joe Bagshaw, Worcester Polytechnic Institute
jbagshaw at wpi.wpi.edu
Roadkill on the information superhighway.

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