Myrabelle B. Lopez Zoo 120.1-AB EXERCISE 1B The Responses of Paramecium to Various Stimuli Stimuli + - + Response Their motion favors the cathode side or the negatively charged electrode over the other. GALVANOTAXIS (electrical current) GEOTAXIS (gravity) + They are situated more on the uppermost layer of the obtained sample and only a few are found in the middle and bottom. Larger number of the organism are perceived in the uncovered section. PHOTOTAXIS (light) THIGMOTAXIS (contact) + CHEMOTAXIS (chemical) Characterized by erratic movements which may be an attempt to avoid the obstacle. Its motion is directed towards the introduced stimuli as it is surrounding the thread dipped in a solution of acetic acid. What Mediates the Response -They are positively charged. -Influence of depolarization and hyperpolarization of its cell membrane. -Upward swimming motion. -Buoyancy and hydrodynamics. -Better access of food in lighter illumination. -Hypersensitivity when stimulated by light. -Tactile response to avoid being preyed on. -Its senses are stimulated by the familiar weak acids being released by its food. Guide Questions 1. Do the Paramecium show any signs of being electrically charged? If so, do they carry a positive or a negative charge? Explain. Yes, it showed signs of being positively charged as it prefers the cathode side over the anode. Its cells manifest a strong negative galvanotaxis due to its ciliary motion that is controlled by the shifts in membrane potential and ion concentration (Machemer & de Peyer, 1977). When an electrical current stimulus is introduced, it modifies the membrane potential which in turn, changes the ciliary movements and affects the cell motion. The cilia on the anode side beat more frequently This study source was downloaded by 100000805920178 from CourseHero.com on 02-24-2022 01:35:16 GMT -06:00 https://www.coursehero.com/file/85985759/Exercise-1B-Lopezdocx/ causing ciliary augmentation (Kamada ,1931) whereas those in the cathodal end beat in the same intensity but in the opposite direction resulting in ciliary reversal (Ludloff,1895). This phenomenon causes asymmetry in the ciliary beatings which is enough to generate a rotational force to orient the cell towards the cathode. From this, a torque is generated due to the interaction between the negative membrane potential (~30 mV) and potential gradient distribution in the medium (Ogawa et al.,2006). Since the cell is forced to swim toward the cathode, it can be inferred that the depolarization occurs and causes the voltage dependent Ca 2+ channels (VDCCs) to be activated and since the intracellular concentration of Ca 2+ ions is extremely low, it further flows into the cell of the Paramecium causing further activation making it positively charged (Naitoh & Kaneko, 1972). 2. In which portions of the upright test tube do Paramecium tend to aggregate. Explain. What is geotaxis? Are the Paramecium positively or negatively geotactic? It is apparent that the Paramecia tend to aggregate in the top layer of the test tube which is congruent with the findings in the study of Kanda (1914) wherein a similar setup of suspending a culture of Paramecia in a vertical test tube resulted in the upward motion of the said specimen. The mentioned experiment is a method devised to observe the impact of gravity to the said protozoan termed as geotaxis or as defined by Temmerman et al. (2013) is the “intriguing phenotype that induces a preference of movement away from or towards the source of gravity.” With the acquired results, it can be deduced that a Paramecium is negatively geotactic as its motion opposes that of gravity. Several studies offer various explanations behind this observed response which are all tested using different setups. Based on the findings of Roberts (2010), the preferential upward swimming pattern and orientation of Paramecium is the primary reason behind its upward trajectories. Roberts also suggested that the mentioned specimen has developed gravikinesis through the interaction of its ciliary propulsion system enabling it to effectively orient itself upward. 3. Is there any other factor which may account for the observed aggregation of Paramecia in the test tube? Enumerate. When subjected to changes in orientation in relation to gravity, this organism actively alters its swimming speed in order to fight sedimentation as a means of seeking favorable conditions (Guevorkian & Valles, 2006). Another factor that may have contributed to the said observation is the concept that the regulation of the swimming speed is primarily related to the buoyancy of the cell and that the anterior end of the Paramecium is heavier than that of the posterior thereby producing a weak effect of the pull of gravity (Kanda, 1914). 4. At which half of the petri dish are Paramecium most numerous? This study source was downloaded by 100000805920178 from CourseHero.com on 02-24-2022 01:35:16 GMT -06:00 https://www.coursehero.com/file/85985759/Exercise-1B-Lopezdocx/ Most number of the said protozoan is situated in the uncovered portion of the petri dish which is exposed to the light. 5. What is phototaxis? Are the Paramecium negatively or positively phototactic? In the broadest sense, phototaxis is the reaction of an organism with respect to light stimulation and it may either result in positive or negative displacement (Access Science Editors, 2016). From the generated response of the Paramecium as viewed in the video, it is apparent that it is positively phototactic. In his study, Okumura (1963), discovered that when stimulated by light after being adapted to a dark and shaded region, changes in a Paramecium’s ciliary beating direction occurred as its photo response is evoked when the ordinary illumination of light was not present. In turn, even when the light source applied is weak, their ciliary activity and swimming velocity recovered. 6. Could this taxis be demonstrated with the tube in a vertical position? Explain. No, this setup will not effectively demonstrate how the Paramecium would react as it is an experimental design that would only show the effect of gravity and not light. With this, the expected result is that they would favor swimming upwards. Furthermore, subjecting these protozoans to a horizontal position shows the necessary transition to test positive and negative phototactic response with 1.5 W m-2, an excess from the 30 W m-2 required to reverse the upward swimming due to the two different stimuli present when in a vertical position (Grell,1973). 7. Distinguish taxis from a tropism. Both taxis and tropism refer to directional response but applies only in specific organisms. Taxis describes how an animal orients itself when a stimulus is introduced which may take the form of a change in its position or movement (Encyclopaedia Britannica, n.d.). On the other hand, tropism mainly refers on how plants and other sessile organisms react to external stimuli which can either be towards or away from the stimuli such as light and gravity (Mead,2008). 8. What is thigmotaxis? Describe what happens when the Paramecium bumps against something. As defined by Patricelli (2010), thigmotaxis is the directed motion towards or away from a contact or touch. From the video, erratic movements of Paramecia were shown as an attempt to avoid and escape the obstacle that it encountered. This study source was downloaded by 100000805920178 from CourseHero.com on 02-24-2022 01:35:16 GMT -06:00 https://www.coursehero.com/file/85985759/Exercise-1B-Lopezdocx/ 9. What is chemotaxis? Does the acid solution cause a positive or negative response in the Paramecia? Chemotaxis is the response generated by an organism from a chemical stimulus. The used chemical stimuli, acetic acid solution rendered a positive response to the Paramecium as its motion is directed towards it. This obtained findings is also mentioned in the study of Nakatani (1968) as the said organism can release filamentous trichocysts, one that is used to deter preys, but for this purpose, it is utilized to also cling to an object to stabilize its position that helps in its optimal ingestion of food. 10. Discuss the implications of the results observed. For this experiment, Paramecium, a widely-studied ciliate was subjected to various stimuli. Despite being a unicellular organism, it is capable of having mechanosensitive organs allowing it to produce a response similar with other higher order organisms. The results showed a Paramecium’s positive response towards electrical current, light, and chemical. From this, it can be deduced that it is positively charged and its movement towards cathode is related to the influence of depolarization and hyperpolarization of its cell membrane, thereby affecting its ciliary movements. Its response towards light shows that it prefers moving rather than being stagnant to an environment devoid of illumination, which may be one of their employed mechanism to have better access for food. Being attracted to weak acids serves as an indicator of food since in the natural setting, they usually prey for microbes that produce weak acid. On the other hand, negative responses for gravity and contact implies their natural preference to inhabit the surface and as explained by various studies, buoyancy and its upward swimming motion mainly contributes to the observed response. Its tactile response demonstrates its mechanism to avoid any barrier which mirrors their natural avoidance to being a prey to other organisms. 11. How do organisms with less complex systems such as those in protozoans are able to respond to stimuli compared to higher forms of organisms? Although they have simple anatomical and physiological aspects, they are equipped with the necessary organelles that enable them to generate a response that would most likely result in a higher chance of survival and engage in efforts that maximizes the presence of favorable conditions. Like every other organism, these simple protozoans are designed to have innate behaviors and learned behaviors that contributes to their ability to thrive. This study source was downloaded by 100000805920178 from CourseHero.com on 02-24-2022 01:35:16 GMT -06:00 https://www.coursehero.com/file/85985759/Exercise-1B-Lopezdocx/ References Access Science Editors. (2016). Phototaxis. AccessScience. doi:10.1036/10978542.br0505161 Encyclopaedia Britannica. (n.d.). Orientation. Retrieved March 02, 2021, from https://www.britannica.com/topic/locomotion/Orientation#ref497026 Grell, K.G. (1973) Behavior. In: Protozoology. https://doi.org/10.1007/978-3-642-61958-8_9 Springer, Berlin, Heidelberg. Kanda, S. (1914). On the geotropism of paramecium and spirostomum. The Biological Bulletin, 26(1), 1-24. doi:10.2307/1535991 Mead, K. (2008). Taxis. Encyclopedia of Ecology, 3483-3489. doi:10.1016/b978008045405-4.00551-6 Nakatani, I. (1968) Chemotactic response of PARAMECIUM CAUDATUM (with 8 TEXTFIGURES). Retrieved March 03, 2021, from http://hdl.handle.net/2115/27465 Okumura, H. (1963). Response to light In Paramecium. Retrieved March 02, 2021, from http://hdl.handle.net/2115/27366 Patricelli, G. (2010). Robotics in the study of animal behavior. Encyclopedia of Animal Behavior, 91-99. doi:10.1016/b978-0-08-045337-8.00227-8 Roberts, A. M. (2010). The mechanics of gravitaxis in paramecium. Journal of Experimental Biology, 213(24), 4158-4162. doi:10.1242/jeb.050666 Temmerman, L., Meelkop, E., & Schoofs, L. (2013). Pigment dispersing factor. Handbook of Biologically Active Peptides, 298-303. doi:10.1016/b978-0-12-3850959.00041-5 Naitoh, Y. & Kaneko, H. (1972). Reactivated Triton-extracted models of This study source was downloaded by 100000805920178 from CourseHero.com on 02-24-2022 01:35:16 GMT -06:00 https://www.coursehero.com/file/85985759/Exercise-1B-Lopezdocx/ Paramecium: modification of ciliary movement by calcium ions. Science 176, 523–524. Machemer, H. & de Peyer, J. (1977). Swimming sensory cells: electrical membrane parameters, receptor properties and motor control in ciliated Protozoa. Ver. Deut. Zool. gesell. 86–110. Kamada, T. (1931). Reversal of electric polar effect in Paramecium according to the change of current strength. J. Fac. Sci. Imp. Univ.Tokyo, Sect. IV, Zoology 2, 299–307. Ludloff, K. (1895). Untersuchungen u¨ber den Galvanotropismus. Arch.Ges. Physiol. 59, 525–554. Ogawa, N., Oku, H., Hashimoto, K., & Ishikawa, M. (2006). A physical model for galvanotaxis of paramecium cell. Journal of Theoretical Biology, 242(2), 314-328. doi:10.1016/j.jtbi.2006.02.021 Guevorkian, K., & Valles, J. M. (2006). Swimming paramecium in magnetically simulated enhanced, reduced, and inverted gravity environments. Proceedings of the National Academy of Sciences, 103(35), 13051-13056. doi:10.1073/pnas.0601839103 This study source was downloaded by 100000805920178 from CourseHero.com on 02-24-2022 01:35:16 GMT -06:00 https://www.coursehero.com/file/85985759/Exercise-1B-Lopezdocx/ Powered by TCPDF (www.tcpdf.org)
