ADAPTATION TO PANTOTHENATE DEFICIENCY 



22-12 



I 1080 1160 1240 1320 



i:i820 1900 1980 2060 2140 2220 2300 2380 2460 2540 2520 



HOURS 



he 



Fig. 22-4A Growth of 2154 cells in pantothenate - free medium 

 (O'V). In duplicate tubes adaptation occurred at different times. Ih 

 number of cells are shown in Table 22-3. These numbers are converted 

 into Klett readings to make ttiis curve comparai)le to fig. 22-4 of 

 whicli fig- 22-4A is an extension. Iwo different time scales are 

 shown; one for Culture I and one for Culture II. Sampling was dis- 

 continued at the points indicated. It is clear that I was already 

 adapted at about 1200 hours. Adapted cells were found in II at around 

 2400 liours, but it is clear from fig. 22-7 that considerable growth 

 occurred previous to the "secondary" adaptation. 



DEMONSTRATIONS OF THE GENIC NATURE 

 OF THE ADAPTATION 



To determine if a gene mutation were involved, one of the adapted 

 (2154) cultures was crossed with different synthesizing and non-syn- 

 thesizing haploid strains. The following tabulation lists the eight cul- 

 tures from two asci described in table 19-3 showing which grew in 

 Burkholder's medium with added pantothenate and which did not. The 

 superscript over the plus indicates the number of days before full 

 growth appeared. The figure in parenthesis after the minus indicates 

 the time required for the cultures to adapt in the absence of added 

 pantothenate. Culture 2154 becomes capable of growth in a medium 

 without pantothenate after 5 days once it has become adapted to the 

 deficient substrate. 



2113 - 



2114 +' 



2115 +' 



2116 - 



040) 



040) 



2151 



2152 + 



3 



2153 +^ 



2154 - 



O30) 



(>30) - 2154 (+5, adapted) 



