586 J. T. HOLDEN 
We can now reconsider the mechanism by which sucrose, although excluded from 
most of the internal volume of the cell, promotes a large increase in the amount 
of glutamate accumulated by B,-deficient cells. Cells which have been pretreated 
with acetate, ammonium ion, glutamate and vitamin Bg, and allowed to synthe- 

$ SU a T 
| -----WIGH Bg CELLS 
80 TOW Bg CELLS ye 
famoles GLUTAMATE / 100 mg CELLS 




MINUTES 
Fig. 9. Effect of acetate, NH,+ and vitamin B, on glutamic acid accumulation by vitamin B,- 
deficient cells of L. avabinosus. See ref. 48 for complete experimental details. The indicated 



supplements were added to standard uptake buffer as follows: @ @, no additions; A VINE 
pyridoxamine (1 ug/ml); X———_X, CH,COOK (0.0057 M) and NH,Cl (0.003 M); © @: 
CH;COOK, NH,Cl and pyridoxamine; @—-——-—@, no additions. (———) B,-deficient cells; 
(~—-—), B,-adequate cells. 
size more cell wall material, are still morphologically abnormal (swollen shape) 
It is unlikely that water influx, especially into intracellular structures, would 
be completely restrained in such reactivated cells, nor, therefore, that internal 
accumulation sites would be significantly protected by this procedure. However 
is likely that an unfavorably large swelling of the internal protoplast with a conse- 
TABLE V 
DISTRIBUTION OF [2-!C]ACETATE IN L. avabinosus 
CELL FRACTIONS 

Cell type 

Fraction HB LB, 
& 
(counts/min|/ro mg cells) * 

Cold TCA 3 000 6 000 
Hot TCA 100 300 
Ethanol 114 000 128 000 
Trypsin I 600 500 
Residue (Wall) 38 000 IQ 000 
* Washed cells were incubated at 1.6 mg/ml in 0.12 M phos- 
phate buffer®* containing glucose (0.028 MW), sucrose (0.5 1), 
K/[2-4C]acetate (0.0059 M). After 60 min at 37° cells were 
centrifuged, the pellets frozen and extracted as described by 
PARK AND Hancock®*. Appropriate aliquots were plated and 
radioactivity measured in a gas-flow counter. 
References p. 592/594 
