Table 1.

Biological activity of mutant binary toxins against mosquito larvae

MutantAmino acid(s) replaced with alanineMutated site in binary toxinLarvicidal effectLC50a for second-instar larvae of:
51-kDa peptide42-kDa peptideC. quinquefasciatusA. stephensi
pSV15None (wild-type toxin) ______________ ______________ Toxic20100
 N          C  N           C
51N4S38KK40
______________

______________
Nontoxicb
51C2I392Q393          ↓
______________

______________
Nontoxic
42N2C47
______________

______________
Nontoxic
42C2R312
______________
          ↓
______________
Nontoxic
51N4
______________

______________
Toxic80200
51C2          ↓
______________

______________
42N2
______________

______________
Toxic140300
42C2
______________
          ↓
______________
  • a Protein concentration, in nanograms per milliliter of the assay medium, required to kill 50% of the larvae in 24 h.

  • b —, not toxic at up to 10 μg of protein per ml.