Figure 8.

Inhibition of apyrase activity in pollen tubes by antibodies decreases tube growth rate and increases the [eATP]. A, Treatment of growing pollen tubes with polyclonal antiapyrase antibodies rapidly decreases their growth rate. Error bars are ±sd and asterisk marks growth rates that are significantly different from that of the buffer control (P ≤ 0.02; n ≥20). The differences in growth rates of tubes treated with preimmune serum and of tubes treated with buffer are not statistically different (P > 0.6; n ≥ 20). Protein concentration of the preimmune sera was 0.3 μg/μL, and of the immune sera was 0.4 μg/μL. B, Treatment of growing pollen tubes with polyclonal antiapyrase antibodies rapidly increases the concentration of eATP in the medium. Medium [ATP] was measured at 1 and 15 min after addition of the treatment solution (buffer control, preimmune sera, or immune sera as in A), and the bar height gives the average fold increase in [eATP] ±sd between the two time point comparisons. The average [eATP] at 1 min was 6.1 ± 0.41 nm for buffer controls, 8.22 ± 1.81 nm for samples treated with preimmune sera, and 6.77 ± 1.38 nm for samples treated with immune sera. Different letters above the bars indicate mean values that are significantly different from one another (P < 0.05; n = 4).