l
Mix a second color of food coloring to view the liquid.
(c) Control: water.
l
Mix a third color of food coloring to view the liquid.
5.5.3 Procedure
l
Suspend the nematode in 100 ml water.
l
Melt 2% agar to make a solution and leave it in a water bath
(55
C).
l
Load a chemoeffector solution into the inlet tubing.
l
Meanwhile, mix the nematode isopropanol mixture with the 2%
agar solution in a 3:1 ratio, and the final agar concentration must
be 0.5% (0.5 ml of the nematode suspension with 1.5 ml of the
2% agar solution).
l
Pipette the mixture of nematode–agar into the other inlet opening after mixing instantly.
l
Draw rapidly and carefully the two solutions into the channel
immediately as the suspension of nematode fills the inlet opening, with the help of the tubing-tipped syringe kept at the outlet
opening.
l
Visualize the channels with a microscope.
l
Observe the nematode number on each side of the channel over
time 5, 10, and 15 min and record.
l
Measure the response of the nematode to the chemoeffector,
applying the equation as follows and calculate the chemotaxis
index (CI):
CI ¼
Number nematodes on chemoeffector side
Total number of nematodes in device
l
A chemotaxis index of 1 indicates that the chemical is a resilient
chemoattractant, and a value of 0 indicates a strong
chemorepellant.
Note: Nematodes may be eliminated by washing them down
a sink or liberating them to the soil outside. The channels used
may be drained with hot water and reused or disposed.
Chemotaxis Assay
45
Mix a second color of food coloring to view the liquid.
(c) Control: water.
l
Mix a third color of food coloring to view the liquid.
5.5.3 Procedure
l
Suspend the nematode in 100 ml water.
l
Melt 2% agar to make a solution and leave it in a water bath
(55
C).
l
Load a chemoeffector solution into the inlet tubing.
l
Meanwhile, mix the nematode isopropanol mixture with the 2%
agar solution in a 3:1 ratio, and the final agar concentration must
be 0.5% (0.5 ml of the nematode suspension with 1.5 ml of the
2% agar solution).
l
Pipette the mixture of nematode–agar into the other inlet opening after mixing instantly.
l
Draw rapidly and carefully the two solutions into the channel
immediately as the suspension of nematode fills the inlet opening, with the help of the tubing-tipped syringe kept at the outlet
opening.
l
Visualize the channels with a microscope.
l
Observe the nematode number on each side of the channel over
time 5, 10, and 15 min and record.
l
Measure the response of the nematode to the chemoeffector,
applying the equation as follows and calculate the chemotaxis
index (CI):
CI ¼
Number nematodes on chemoeffector side
Total number of nematodes in device
l
A chemotaxis index of 1 indicates that the chemical is a resilient
chemoattractant, and a value of 0 indicates a strong
chemorepellant.
Note: Nematodes may be eliminated by washing them down
a sink or liberating them to the soil outside. The channels used
may be drained with hot water and reused or disposed.
Chemotaxis Assay
45