The Effect of Sodium Chloride on The Swimming Behavior of Paramecium

The Paramecium tetraurelia is a unicellular organism belonging to the kingdom of Protists. It can be found mostly in a fresh water environment and is covered in hair-like structures known as cilia. The cilia help with locomotion, allowing it to move forward and backwards. It also helps in “bringing” the food to the cells. The Paramecium is an ideal cell to study do to the fact that its swimming response changes when introduced to new stimuli. The cells are also easily observable and its cell membrane “contains many proteins, including calcium, potassium, and sodium ion channels”. The channels in the cell membrane allow ions to cross over from high concentrated areas to low concentrated areas. This controls the cells membrane potentials which consequently “controls the swimming behavior” of the Paramecia. (Clarke et al. , 2002) Sodium Chloride, NaCl, is known as table salt.

Sodium chloride in the physical form is a white crystalline cube. It is essential in maintaining our blood pressure, absorb and transport nutrients, and retain the right balance of fluid. If there is too little or too much of NaCl in your body, there will be issues. (Haskins, 2016)) As a result, we decided to observe what happens when sodium chloride is introduced into the environment of the Paramecium. From previous experiments we found that when the Paramecium was exposed to chemicals, their swimming behavior would change. We wanted to see how NaCl, which is so prevalent in the environment, would affect them. The hypothesis was that if we added NaCl to the Paramecium tetraurelia culture then the vector changes per second would increase. The null hypothesis, subsequently, was that the when NaCl is added to the Paramecium tetraurelia culture then the vector changes per second will decrease. To conduct our experiment, we needed Paramecium tetraurelia culture, NaCl, 1x Dryl’s Medium, Pipettes, a dissecting microscope, a millimeter grid, electrophoresis chamber, and a 50mL/100mL graduated cylinder. The independent variable in the experiment was sodium chloride, the dependent variable was behavior of the cell, how many vectors changes per second. The standardized variables are the Paramecium tetraurelia culture, electrophoresis chamber, and Dryl’s solution. There are two levels of treatment in this experiment. In the first level of treatment was conducted without NaCl added to the Dryl’s solution. The second level of treatment was conducted with NaCl added to the Dryl’s solution. The control treatment was that NaCl was not added to the Dryl’s solution. We had six replications and ad a sample size of 12.

We started with the control treatment, which included 250 mL of Dyl’s solution alone. We first gathered our materials and then connected the dissecting microscope. We then collected 250 mL of Dryl’s solution in a graduated cylinder which we then poured into the electrophoresis chamber. We placed a millimeter grid on the stage of the electrophoresis chamber, and poured the Paramecium culture into the solution. After waiting for 1 minute, to allow the Paramecium to get used to the environment, we then took turns to observe the Paramecium. Each person looked through the microscope and focused on one Paramecium while another person held the stopwatch. The person observing would tell the person with the stopwatch to start the stopwatch after they had focused on one Paramecium to observe. After the stopwatch beeped, alerting the observer that ten seconds was done, they recorded how many vectors the Paramecium had done in the 10 seconds and then divided that by 10 to get vectors per second. After each person observed and recorded the data 4 times each, we continued on to the experimental treatment.

The experimental treatment included Dryl’s solution with NaCl. For this treatment, however, we decreased the amount of Dryl’s solution in order to maintain a constant volume of 250 mL, we added 225 mL of Dryl’s solution and 25 mL of sodium chloride. After making sure we cleaned out our electrophoresis chamber thoroughly, we added 225 mL of Dryl’s solution from the graduated cylinder, placed the millimeter grid and then evenly dispensed 25 mL of NaCl from the graduated cylinder. We then poured the Paramecium culture and waited for one minute, allowing the Paramecium to get used to the new environment and NaCl. We then continued on as for the control treatment, where each person observed a Paramecium for 10 seconds while another person held the stopwatch. After each person had recorded their data we compared the two data from each level of treatment. We calculated the mean, standard deviation, and a t-test. In Figure 1, the bar graph shows the data for vector changes per second for both the control and experimental treatment. The columns represent the average vector change per second for each of the treatment levels, control and experimental. The error bars represent the standard deviation for each of them. Based on the figure you can see that there was a decrease in vector changes per second when NaCl was added. However, the difference is too small to conclude whether or not the number of vector changes was due to the addition of NaCl. The mean for the control treatment was 1. 0 vector changes per second and the standard deviation was 0. 453 vectors/sec. The mean for the experimental treatment was 0. 8 vectors per second and the standard deviation was 0. 280vectors/sec. In Table 2 you can see that the t-calculatedwas 1. 333, the t-critical for 95% confidence level was 1. 654, the degrees of freedom was 172. The t-calculated was less than t-critical at 95%, which means that there wasn’t a significant difference between the control treatment and experimental treatment. Discussion and Conclusions:

The class hypothesis was that when NaCl is introduced to the Paramecium’s environment, the vector changes per second would increase. However, after conducting the experiment we concluded that our hypothesis was wrong, the data did not support our hypothesis. The null hypothesis was correct, which stated that the presence of NaCl will decrease the vector changes per second. The results show us that there was a decrease in the vector changes per second in the experimental group, however, since the difference is so small we cannot conclude if decrease was due to the NaCl or other factors. The different culture taken during the experimental group could have been slower causing the difference in the number of vector changes. Also, the amount of NaCl added to the Dry’s solution could’ve been too small to result in better outcomes.

For future directions, new levels of treatment can be added in which there is a control treatment, and experimental treatments in which each level has different amounts of NaCl. If a significant amount of NaCl is added, there is a possibility that it would increase the vector changes per second thus proving the hypothesis. In addition, a basic guideline can be set to determine how to count the vector changes. Someone might count turning a little as a vector change while another says a vector change is when the flip to another direction. Having a guideline to follow, everyone can measure the vector changes correctly, so no confusion is created in determining which should and shouldn’t be considered as a vector change.