TABLE 3.

Effect of embryonic stage on microinjection efficiency in embryos of parthenogenetic strain B. mori 1–31 incubated at 15°C.

Timing of injection after heat-shock activation (at 15°C)	No. of injected eggs	No. of died eggs	Expression of EGFP		Hatched larvae
			Not expressed	Expressed
12 h	48	12 (25%)	2 (6%)	34 (94%)	0 (0%)
18 h	48	5 (10%)	3 (7%)	40 (93%)	7 (16%)
24 h	48	10 (21%)	2 (5%)	36 (95%)	2 (5%)
30 h	48	12 (25%)	1 (3%)	35 (97%)	1 (3%)
48 h	48	3 (6%)	30 (67%)	15 (33%)	3 (7%)
72 h	47	1 (2%)	33 (72%)	13 (28%)	16 (35%)

GFP-containing DNA plasmid was injected into the heat-shock-activated eggs during the first 72 h AEA at the times indicated in the first column. The number of GFP-positive embryos examined 4 days before hatching reflects the efficiency of microinjection. Mortality of injected embryos and hatchability success of transgenic larvae were also examined. The corresponding percentages are given in parentheses.