clustering of EMS mutations, again

Gary Vanzin gfv94001 at uconnvm.uconn.edu
Tue Nov 19 00:21:22 EST 1996


Thank you to everyone who replied to my original message.  Your responses 
alerted me to how I slightly mis-stated my predicament.
	I have sequenced seven independently segregating mutant alleles (of 
the same gene), with each allele containing a single mis-sense mutation.  
These mutations, when compared to the cDNA sequence, are clustered within 
about 400 bases.  These seven mutant plants were isolated from 5200 EMS 
mutated lines, originally screened for the mutation through gas 
chromatography.  From 5200 lines, one would normally expect much less than 
seven independent mutations within a single 1.2Kbp gene.   My question is, 
has anyone seen this increase in EMS mutagenesis frequency within a gene?  
Our gene is involved in cell wall synthesis, so we can hypothesize that while 
the EMS is mutating the DNA, our cell wall biosynthesis gene is being highly 
transcribed, thus leaving it open to mutation.  
	For those who replied that there may have been more than seven 
mutations, but they were not phenotypically identified, this makes even less 
sense.  If seven EMS mutations within a 1.2Kbp gene is already above average, 
one would not expect even more, undetected mutations.  
Again, thank you to those who took time to reply.  If anyone has an ideas, 
please contact me.


Gary Vanzin
University of Connecticut
Department of Molecular and Cell biology
Storrs, CT 06268
gfv94001 at uconnvm.uconn.edu




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