En2 is a derivative of En1 (wx844) that is deficient in ORF2 and part of ORF1 of the En element. The remainder of the element (11 exons) is intact. When tested for the two genetic functions of En, the S function is expressed. Not, however, completely, because gown coloration is evident in En2 a-m15719 (a-m15719 is colored in the absence of En). The low frequency of spots with this same combination indicates that the M function is minimally expressed. These conclusions are limited to the observation of En2 with a-m15719. Do these observations define the functionality of the element? When another responder is used, a totally different picture is seen. With a-m(Au)pale m(r)871618W-1 the response is relatively quite high mutability. It is this writer's conclusion that the a-m15719 allele does not adequately gauge the potency of En2, implying therefore that the limits of the full functionality of ORF1 have not been determined. A further observation of this functionality of the TNPA (S) function is seen in the progeny of a self of Wx/wx860246x. When heavy gown color is selected, they are all found to be Wx. If this proves to be consistent, it would mean that the dosage (Wx/Wx/wx860246x vs. wx860464/ wx860246x) of the TNPA protein is significant in expressing the potency of the S function.
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