The filter paper is sealed in a freeze vial. Open the vial and take out the filter paper. Some cultures may exhibit a prolonged lag period and should be given twice the normal incubation time before being discarded as nonviable. Pick several isolated colonies and check for markers and ploidy. If only a patch of growth occurs, streak out to obtain isolated colonies, pick several and check as above.
Every effort is made to provide strains having the exact requirements as listed in the catalog.
We urge checking the strains before extensive use. Spontaneous papillation to canavanine resistance also occurs in haploid cells but at a much lower level. Viability patterns of dissected spores are indicative of ploidy and of other chromosomal rearrangements. If all cells have diploidized and one needs the haploid mutant, it is necessary to go through genetic manipulations. YGSC scientists are always ready to suggest the easiest route to be followed and will substitute other haploid strains, if available, or will try to provide appropriate strains for any genetic analyses that may be required.