Patrick Ferris and Ursula Goodenoough need an allele that can serve
as a control in an experiment designed to assess mutation frequencies
in sex-related genes in Chlamy. The allele need to carry a point
mutation, as determined by DNA sequencing, that is known to revert
very infrequently under standard lab culture conditions. It cannot
be linked to mating type, nor can it heavily compromise mating
efficiency when carried by gametes of both mating types in a cross
(i.e. most pfs would not be suitable). Revertants need to be
detectable by some screening procedure that can be applied at the
plate level (e.g. auxotrophy --> prototrophy), and ideally they
should not be readily confused with mutations at other loci, albeit
this could be sorted out genetically.
If any of you knows of a marker with these properties, please let us know!