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RFLPs Theory

Keith Robison robison at ribo.harvard.edu
Tue Nov 19 13:01:57 EST 1991


>From:   FRCU::NAGEL        "MUHAMMAD W. HEGAZY" 19-NOV-1991 15:11:49.60

>Can anybody explain in details the theory of using RFLPs in determining
>the genetic variation between 2 organisms giving an example of a simple
>Mendelian trait like plant height ??

>I care very much about the relation between Mendelian Genetics and
>Molecular Genetics.

>Khaled Mahmoud
>Research Assistant
>National Agricultural Genetic Engineering Laboratory (NAGEL)

	I'm no expert in this area, but I'll give it a try.

	For the most part, RFLPs behave as phenotypically-neutral Mendelian
co-dominant traits.  The great advantage of RFLPs and other such molecular
markers ("RAPDs" and some types of PCR-based DNA fingerprinting) is that it is
easy to generate large numbers of these markers.  You can then perform 
conventional crosses and look at large numbers of Mendelian traits, giving a 
high probability of the locus controlling the phenotypic trait of interest 
landing near one or more marker loci (the RFLPs), allowing mapping of the 
	The neutrality of most RFLPs is one of their key advantages, because
it means that there are enormous numbers of them lying around in natural 
genomes (because there has been little selection against them).  No 
mutagenesis or mass screening of organisms needed. In general, RFLPs are 
most easily found be comparing two distantly-related but still interfertile
organisms (For example in mouse M.spretus x M.Musculus crosses are used)
	If you need further information, David Botstein, Eric Lander, and
Steven Tanksley have written a number of papers on the subject (I name
these authors because they pop into my head -- I know there are many others).
Tanksley in particular works with using RFLPs to nail down quantitative trait
loci in plants, so you might find him particularly interesting.

To the community: If I've made any gross errors, please feel free to correct 

Keith Robison   G1
Harvard University
Program in Biochemistry, Molecular, Cellular, and Developmental Biology

robison at nucleus.harvard.edu

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