CHEMOTAXIS OF SLIME MOLD Shuntarou Oishi Haruka Tsuruoka

CHEMOTAXIS OF SLIME MOLD Shuntarou Oishi 　　 Haruka Tsuruoka　　 　　Miku Nariyama　 　　 Haruka Nishimura

Summary Slime mold naturally avoids chemical substances that it dislikes. We tried to make an evacuation map to test this ability. We found out about how slime mold reacts to chemical substance because we had questions about the nature of slime mold.

Introduction Slime molds are single-celled organisms. They are divided into two kinds. They are Physarum and Dictyostelium. 　 Both of them like dark and wet places. Slime molds can move freely. Slime molds avoid citric acid. So we tested using other acids.

Experiment 1 Does slime mold spread equally without stimuli? Do slime molds move differently on the outside and the inside?

Hypothesis Slime mold spread equally when it gets a stimulus. The outside of slime mold is more expandable than the inside of it.

Result ①They spread equally without stimuli. ②They didn’t spread equally without stimuli. A Outside Inside B C 　① 100% 　① 90% 　② 10% 　① 70% 　① 100% 　 　② 30% 　① 80% 　② 20%

Slime mold spread equally without stimulus. Slime molds don’t move differently on the outside and the inside. 　　

Tube structure of Slime mold 　　　　　 Inner layer 　　　　　 　　　　　

Experiment 2 How does slime mold react to each chemical substance?

①Succinic acid 0. 1 mol/L Succinic acid 0. 5 mol/L 1. 0 mol/L

Experimental method Negative　ｃhemotaxis 　　　　　　　　Positive　chemotaxis 　　　　　　　

For measuring p. H

Hypothesis Slime mold shows negative chemotaxis.

Result negative chemotaxis 　　 positive chemotaxis

p. H～Succinic acid～ 〈0. 1 mol/L〉 〈1. 0 mol/L〉 p. H 6. 3 p. H 5. 4 p. H 4. 8 p. H 4. 5 p. H 5. 4 p. H 4. 6 p. H 4. 2 p. H 4. 0 〈0. 5 mol/L〉 p. H 5. 9 p. H 4. 2 p. H 4. 9 p. H 4. 4 : 3 cm : 2 cm : 1 cm : 0 cm

②Oxalic acid ＜The chemical substance which I used＞ 　　☆oxalic acid　 0. 1 mol/L , 0. 5 mol/L , 1. 0 mol/L

Experimental method 　☆We did the same experiment as with succinic acid. 　☆But we didn’t experiment to examine positive chemotaxis against oxalic acid of 0. 5 mol/L and 1. 0 mol/L.

Hypothesis Slime mold will show negative chemotaxis.

Result(negative)～ 0. 1 mol/L～ Immediately after the experiment One day later ↑Experiment of negative chemotaxis p. H 6. 1（Center）

Result(positive)～ 0. 1 mol/L～ Experiment of positive chemotaxis↓ One day later Immediately after the experiment p. H 6. 6(0. 7 cm) p. H 6. 9(3. 0 cm) Slime mold

Result～ 0. 5 mol/L～ the next day of experiment 　0. 8 cm→ 　　1. 1 cm→ One day later Experiment of 　 negative chemotaxis

Result☆p. H☆ p. H 4. 7(1. 1 cm) 　slime mold p. H 4. 4(0. 8 cm)

Result～ 1. 0 mol/L～ Immediately after the experiment One day later Experiment of 　 negative chemotaxis 2 cm the next day of experiment

the next day of experiment Continuation Experiment of 　 negative chemotaxis Four day later After 5 days of the experiment

☆p. H☆～ 1. 0 mol/L～ 　 p. H 4. 3(2. 0 cm) the next day of experiment ※we could not find the outside boundary. p. H 4. 1(2 cm) p. H 3. 8(0. 6 cm) p. H 3. 8(0. 4 cm) After 5 days of the experiment

Result～Oxalic acid～ 0. 1 mol/L 0. 5 mol/L 1. 0 mol/L Positive negative⇒ Oxalic acid chemotaxis positive ※『negative⇒positive』 means after the slime mold showed a negative chemotaxis, it showed positive chemotaxis.

Discussion of Experiment 2 ☆We think slime mold doesn’t have chemotaxis against succinic acid. ☆At first, slime mold made a stop circle because 　 p. H of oxalic acid was less than 4. 　 But then, slime mold showed positive chemotaxis 　 when the p. H was more than 4. 　 Because there was a slime mold in less than p. H 4 , when we experimented with oxalic acid 1. 0 mol/L, slime mold is likely to exhibit some chemotaxis to something other than p. H.

Outlook 　We want to examine the chemotaxis of slime molds against substances with a carboxyl group. 　And, slime molds don’t move by only p. H, so we want to test how substances affect slime molds For example: The relationship of organic acids and cell membrane receptors.

Thank you for listening!!