Dale, The use of the term hemizygous is not "hair splitting" it is just what you should have learned in your first genetics course! Again it is very humorous of you to pretend that elementary genetics does not matter and that you can use misleading terms suggesting that there are natural alleles to the bacterial transgenes, you provide great comic relief! Sincerely, Joe Dale Wilson wrote: Hi Chuck,Friends, the ongoing dialogue over GM crop genetics is getting into very interesting deep water.I just got back from a little vacation on Kelly's Island. Looks like I missed some interesting debate. But I will catch up as time allows."Transgenic crops are either homozygous or hemizygous but practically never heterozygous. A heterozygous transgene would normally arise ifahomozygous diploid suffered a mutational change on one of the alleles to inactivate the allele or to alter its activity."Some people use the term hemizygous when there is not a corresponding allel on the homologous chromosome. I think this is needless hair-splitting. My point was that most transgenic corn varieties only have the transgene on one of the homologous chromosomes. The transgene is only placed in one of the parents used in hybrid seed production, usually the male parent. This is done because it is cheaper and more flexible. Thus, when typical transgenic corn produces gametes, half bear the transgene and half do not.First, if Monsanto had a RR soybean variety that was heterozygous, it would deep six it because it would not perform with sufficient reliability, right?The situation is entirely different with soybeans because they are a self-pollinating species. They are essentially homozygous at all loci. They must be so to be stable and to breed true. But hybrid corn does not breed true, whether it is transgenic or not. It is not a pure line, it is a hybrid.when the pollen from a homozygote RR variety crosses with a non-GMO variety. The seed produced by that conventional-non-GMO plant pollinated cross could be heterozygous -- or if I understand Joe, hemizygous -- but never homozygous, or perhaps I just drowned.Don't drown in the jargon. In this context, heterozygous and hemizygous have the same practical consequence. That is that the frequency of the transgene is one-half the frequency of the frequency of transgenic individuals. The only reason this is important is to allow accurate estimation of the frequency of transgenic contamination in OP populations of cross-pollinated species. The situation is more complicated for stacked products (more than one transgene). But in all these cases, the methods to calculate the probability of encountering any particular combination have long been worked out based on gene frequencies. Dale __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com ******************************************************** To unsubscribe from SANET-MG: 1- Visit http://lists.sare.org/archives/sanet-mg.html and unsubscribe by typing in your e-mail address or; 2- Send a message to <listserv@sare.org> from the address subscribed to the list. Type "unsubscribe sanet-mg" in the body of the message. Visit the SANET-MG archives at: http://lists.sare.org/archives/sanet-mg.html &NBSP; ***************************************************** To unsubscribe from SANET-MG: 1- Visit http://lists.sare.org/archives/sanet-mg.html
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