Chemotaxis 15 mL of an optimized nematode chemotaxis medium

Chemotaxis plates are
prepared with 10cm Petri dishes containing 10ml of assay agar (2% agar, 5mM KPO4
pH6, 1mM CaCl2, 1mM MgSO4). c.elegans have to be washed
twice in S-basal, once in distilled water and placed onto spot on the plate.
Mark two spots equidistant from center diameter on the bottom of petri dish,
mark them as A and B. Mark the spot X on the circumference of the petri dish
forming a triangle with A and B1µl of 1:100
benzaldehyde:EtOH is placed at test spot A and 1µl of ethanol was applied to
the other spot B. C.Elegans are added at spot X. For each spot, 1µl of 1 M NaN3
was applied to immobilize the worms when they reached the spot. After one hour of
chemotaxis, animals were counted, and Chemotaxis Index (CI)  = A-B/A+B+X is calculated.Repeat the steps 2,3 with a
different concentration of 1µl of 1:1000 benzaldehyde:EtOHFor locomotor assay, take
C.elegans grow on NGM with OP50 in nicotine-free plates. They are placed on
fresh plates 5-6 hours before the behavioral test. C.Elegans are then
transferred to plates with appropriate nicotine concentration. Observations are
recorded.Discard the results from first
10-12 minutes as the elegans get adjusted to new enviroment. The results give
us insight of Acute Locomotor Assay.Elegans from step 5 are then
taken to measure the Locomotor Sensitization Assay. Transfer worms to a clean
plate containing a lawn of OP50 and 100 ?M nicotine before transferring them to
a second clean, nicotine-free plate for an additional hour. Observe how the elegans
crawl on a plate covered in 40 ?L OP50 and a 10 ?M Nicotine concentration. For chemotaxis assays, we
used standard 10 cm Petri dishes containing 15 mL of an optimized nematode
chemotaxis medium 1.6% BBL agar; 1 mM MgSO4; 1 mM CaCl; 5 mM

KPO4. Mark the plates for A,B and X for attractant, control and middle

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Transfer elegans to the
chemotaxis plate by adding 10?L nicotine diluted in ethanol at A and the
control, ethanol diluent at B. Placed the dishes upside
down and allow to sit undisturbed for one hour.Observations are recorded at
the end of the hour. Chemotaxis index (CI) is calculated by counting the number
of elegans using the formula: (A-B)/(A+B+X) = CI.


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