We shall go ahead with the absolute pantothenicless when they arrive. Owing to their sterility, they will be of doubtful value
in locating sensitive p locus.
Your concept of the necessity of locating pts is essentially correct. The aberrant region, located by Mal, is by no means
negligible, and the general handling of the diploids is such as to make some readily scored colonial (i.e. fermentative) marker
almost obligatory. It would be best to have data from 58-161 xW677 or 1177 with p segregating, p- and p+ being then compared
for the distribution of Lac, Mal, V1, Mt1, etc. In fact, I should say that there would be very little point in your visiting
to work on the heterozygotes until these data are obtained. Of course, this means you will have to have the necessary 58-161
or W-1177 pts stocks: it would be much better to have pts in W-1177 or in W-677. This may necessitate a brief postponement
of your visit, but perhaps you can have the material ready in time, with some luck.
If you succeed in reisolating W-677 pts, but do not have time to complete the linkage work, it might be profitable to spend
some days on this aspect if next month is the only convenient time for your visit. Let me know what the status of things is
likely to be. In any event, we shall be happy to see and discuss these problems with you.