Table 3.

Influence of X-ray irradiation on the viability of F1 progeny from RNAi-treated animals

X-ray dose (Gy)	Hatching rate (%)
	Control	D2005.5 (RNAi)	rad-51 (RNAi)	Y66D12A.15 (RNAi)
0	91.8 (n = 622)	32.5 (n = 382)	62.4 (n = 86)	1.1 (n = 451)
40	62.8 (n = 756)	0.6 (n = 313)	3.2 (n = 313)	0.0 (n = 574)

The cDNA fragments corresponding to D2005.5 and rad-51(Y43C5A.6) were amplified from phage cDNA clones yk331a2 and yk401c3 (a kind gift of Dr Y. Kohara, National Institute of Genetics, Japan), respectively, by PCR with the primer set yk5′-F (5′-TGGCGGCCGCTCTAGAACTAGTGGATC-3′) and yk3′-SmaR (5′-TTCCCGGGTGAATTGTAATACGACTCACTATAGGGCG-3′). These cDNAs were used for X-ray-induced embryonic lethality assay. The genomic DNA fragment (∼2.3 kb) corresponding to Y66D12A.15 was amplified from C. elegans genomic DNA (N2 strain) by PCR using the primer set Y66Dex1-3F (5′-AAGCTTGAAAAACCCAGAAAAATGGCA-3′) and Y66Dex1-3R (5′-TTCCACTCCAACCTTGGTCGCATCGGC-3′). These fragments were cloned into the dsRNA expression vector, and the nucleotide sequences were confirmed by sequencing. Four young adult worms were fed bacteria-expressing dsRNA to the target gene on an RNAi plate for 18 h and were subsequently X-ray-irradiated (Radioflex 320CG, RIGAKU, Tokyo) at a rate of 2 Gy/min. Irradiated animals were transferred onto a fresh RNAi plate, cultured for 2 days to lay eggs and then removed. After 24 h, the hatching rate of eggs laid on the plate was determined. The total numbers of eggs counted are indicated in parentheses.