TABLE 4.

Effect of irradiation on P additions in wild-type and SCID cells^a

Cell line	No. of P added	Irradiation
		None [no. (%)]	100 cGy [no. (%)]
VL3-3M2	0	5 (45)	5 (38)
	1–3	6 (55)	8 (62)
	4–11	0 (0)	0 (0)
	Avg, SD	1.33, 0.82	1.63, 0.52
LK6.2	0	3 (18)	13 (43)
	1–3	6 (35)	13 (43)
	4–11	8 (47)	4 (14)
	Avg, SD	4.50, 2.47	2.59, 1.80

^aThe number and percent of intact coding ends that have the indicated numbers of P nucleotides added are shown for each group. Shown is a summary of data from Fig. 1 and 2. Since the time of irradiation (relative to transfection) did not alter the distribution of P nucleotides, all the data for irradiated cells from Fig. 1 and 2 have been pooled. The calculations are restricted to intact coding ends because P additions are not observed when there is deletion from the coding end. The difference between the lengths of P additions in untreated VL3-3M2 and LK6.2 cells is statistically significant (Mann-Whitney U test, U = 7.0; two-tailed P value, 0.003). The difference between the lengths of P additions in untreated and irradiated LK6.2 cells is also statistically significant (Mann-Whitney U test, U = 60.5; two-tailed P value, 0.018).