Reduced chromosome aberration complexity in normal human bronchial epithelial cells exposed to low-LET γ-rays and high-LET α-particles

Figures & data

Figure 1. Survival curve for NHBE cells following exposure to high-LET α-particles (circle) and ⁶⁰Co γ-rays (square; error bars represent standard deviation, n = 3). The variation in surviving fraction, S, as a function of dose, D, was fitted to equation S = exp(−αD − βD²) where α = 2.22 ± 0.02 and β = 0 for alpha-particles and α = 0.27 ± 0.03 and β = 0.021 ± 0.004 for γ-rays.

Table I. Frequency of chromosomal damage induced in NHBE cells after exposure to γ-rays.

Test	Total cells	Frequency Abnormal	Frequency Simple				Frequency Complex				Frequency PCC breaks Total
			Total	Complete	True-incomplete	One-way	Total	Complete	True-incomplete	One-way
Sham	171	0.123	0.006	0	0.006	0	0	0	0	0	0.170
0.5 Gy	179	0.168	0.061	0.022	0	0.039	0.011	0	0	0.011	0.151
1.0 Gy	106	0.217	0.106	0.047	0	0.057	0.038	0	0	0.038	0.198

Table II. Frequency and sub-classification of PCC breaks.

Test	Cells	Frequency of PCC break types
		Total	Terminal deletion		Truncated chromosome	Excess fragments
			Proximal	Non-proximal
Sham	171	0.170	0.070	0.064	0.035	0
0.5 Gy γ-rays	179	0.151	0.056	0.045	0.045	0.006
1 Gy γ-rays	106	0.198	0.047	0.094	0.038	0.019
Sham pooled	422	0.145	0.047	0.050	0.038	0.009
˜ 1 α-particle/nucleus
24 h	230	0.709	0.209	0.339	0.057	0.104
29 h	313	0.310	0.102	0.141	0.042	0.026
34 h	139	0.367	0.058	0.165	0.115	0.029
Pooled	682	0.456	0.129	0.213	0.062	0.053

Table III. Frequency of chromosomal damage induced in NHBE cells after exposure to ˜ 1 α-particle/nucleus.

Test	Total cells	Frequency Abnormal	Frequency Simple				Frequency Complex				Frequency PCC breaks Total
			Total	Complete	True-incomplete	One- way	Total	Complete	True-incomplete	One-way
Sham
24 h	103	0.126	0	0	0	0	0	0	0	0	0.184
29 h	196	0.147	0.015	0	0	0.015	0	0	0	0	0.194
34 h	123	0.041	0.016	0	0	0.016	0	0	0	0	0.033
Pooled	422	0.111	0.012	0	0	0.012	0	0	0	0	0.145
˜ 1 α-particle/ nucleus
24 h	230	0.443	0.156	0.061	0.047	0.047	0.096	0.008	0.043	0.043	0.709
29 h	313	0.275	0.105	0.032	0.038	0.035	0.035	0.009	0.013	0.013	0.310
34 h	139	0.345	0.108	0.036	0	0.072	0.065	0	0.029	0.036	0.370
Pooled	682	0.346	0.123	0.043	0.034	0.047	0.062	0.007	0.026	0.028	0.456

Table IV. Minimum number of chromosomes and breaks in each complex exchange.

Minimum number/complex		Low-LET γ-rays Frequency observed		˜ 1 high-LET α-particle/nucleus Frequency observed
Chromosomes	Breaks	0.5 Gy	1.0 Gy	24 h	29 h	34 h
2	3	–	0.250	0.017	0.013	0.007
	4	0.500	–	0.017	0.003	–
	5	–	–	0.004	–	0.007
3	3	–	0.250	0.017	0.010	0.007
	4	–	0.250	0.017	–	0.022
	5	–	–	0.009	–	–
4	3	–	–	–	–	–
	4	0.500	–	–	0.006	0.014
	5	–	–	0.004	–	–
5	6	–	–	–	–	0.007
	7	–	–	–	–	–
	8	–	–	0.004	–	–
6	6	–	0.250	–	–	–
	7	–	–	0.004	–	–

Figure 2. Distribution of chromosomal exchanges in aberrant spreads observed 24 hours after exposure to (A) 0.5 or (B) 1.0 Gy γ-rays. The fraction of damaged cells that contain 1 (dark), 2 (light) or > 2 (medium) simple exchanges (simple) or simple + complex exchanges (complex) are shown. Error bars represent standard deviation.

Figure 3. Distribution of chromosomal exchanges in aberrant spreads observed (A) 24, (B) 29 and (C) 34 hours after exposure to ˜ 1 high-LET α-particle/nucleus. The fraction of damaged cells that contain 1 (dark), 2 (light) or > 2 (medium) simple exchanges (simple) or simple + complex exchanges (complex) are shown. Error bars represent standard deviation.

Table V. Simple and complex exchanges classified as transmissible.

Test	Cells	Reciprocal translocation (2B)			Transmissible complex
		Total	Complete	One-way	Total	Complete	One-way
Sham pooled	490	0.010	0	0.008	0	0	0
0.5 Gy γ-rays	179	0.045	0.017	0.028	0	0	0
1 Gy γ-rays	106	0.094	0.047	0.047	0	0	0
1 α-particle/nucleus
Pooled	682	0.087	0.032	0.031	0.013	0.001	0.009