TABLE 1.

Insecticidal activity of B. thuringiensis Cry3A crystal proteins containing the AAPF mutation with first-instar WCR larvae

Samplea	α-Helix 3/α-helix 4 loop regionb	% Mortality (mean ± SD)c
Cry3A	NPVSS_RNP	34 ± 23 A
Cry3A mutant 1	NPAAPF__P	93 ± 4 B
Cry3A mutant 2	NPAAPF_NP	72 ± 13 C
mCry3A	NPAAPFRNP	92 ± 7 B
Chymotrypsin-treated mCry3A	—d	68 ± 7 C
Buffer alone	—	7 ± 7 D

^aAll toxins were purified from B. thuringiensis as crystal preparations. The concentration of each toxin was 100 μg/ml in 50 mM NaHCO₃ (pH 10.0) buffer.

^bThe first N corresponds to N153 of B. thuringiensis Cry3A (49) for the unprocessed toxins.

^cMortality values were transformed using the arcsine square root of the proportion transformation for analysis; actual means are shown. Means followed by the same letter are not significantly different (P > 0.05, Student-Newman-Keul test; n = 6).

^d—, not applicable.