On 2014 Nov 09, Gary Ward commented:

We reported in this paper that the enhancers of invasion and motility identified in the screen do not stimulate an increase in parasite intracellular calcium levels. This conclusion was based on semiquantitative microscopy-based measurements of the fluorescence intensity of the calcium reporter Fluo-4 in individual parasites, before and after treatment with enhancer. More recent quantitative experiments on populations of parasites using the ratiometric calcium reporter Fura-2 showed that treatment with three of the four enhancers tested does in fact stimulate an increase in parasite intracellular calcium levels (Tang Q, 2014); results with the fourth were inconclusive due to spectral overlap between the compound and indicator.

The discovery that some, and perhaps all, of the enhancers identified in the screen increase parasite intracellular calcium levels provides a rationale for how this group of structurally diverse compounds can cause the same set of phenotypes, i.e, enhanced invasion, microneme secretion and motility.

On 2014 Nov 09, Gary Ward commented:

We reported in this paper that the enhancers of invasion and motility identified in the screen do not stimulate an increase in parasite intracellular calcium levels. This conclusion was based on semiquantitative microscopy-based measurements of the fluorescence intensity of the calcium reporter Fluo-4 in individual parasites, before and after treatment with enhancer. More recent quantitative experiments on populations of parasites using the ratiometric calcium reporter Fura-2 showed that treatment with three of the four enhancers tested does in fact stimulate an increase in parasite intracellular calcium levels (Tang Q, 2014); results with the fourth were inconclusive due to spectral overlap between the compound and indicator.

The discovery that some, and perhaps all, of the enhancers identified in the screen increase parasite intracellular calcium levels provides a rationale for how this group of structurally diverse compounds can cause the same set of phenotypes, i.e, enhanced invasion, microneme secretion and motility.