Effect of Light to the Growth of Physarum Polycephalum

An Experimental Study on the Effect of Light to the Growth of Physarum Polycephalum Xiaoyang Han BioSci 152, Section 809 Slime Mold Experiment Report INTRODUCTION Long before we came to evolve and even way before the gigantic dinosaurs thrived on Earth, bacteria, fungi, protist, and algae have already existed. They are the first living things that dwell on earth. It is amazing how they have managed to survive despite their simple forms where huge multi-celled organisms die and become extinct. Protist, the focus of this experiment which will be represented by the organism Physarum polycephalum, is a group which is very much diverse and had been acknowledge recently that it is polyphyletic (Sandgren, et al.,6). This means that it consists of organisms that have separate lineages (6). Brown algae, diatoms, dinoflagellates, euglenoids, slime molds, and water molds comprises some of the organisms of this group (6). The representative organism, Physarum polycephalum, is a bright yellow plasmodial slime mold or generally known as true slime mold under the class/superclass Myxogastridae which belongs to the supergroup Amoebozoa (“Genome: Physarum Polycephalum”). A plasmodial slime mold is characterized as one large cell that contains multiple diploid nuclei that undergo division at exactly the same time and can grow from a few millimeters to around 12 inches in diameter depending on the species (“Genome: Physarum Polycephalum”). It has amoeboid movement and survives by engulfing bacteria and other microbes and secretes enzymes to digest the engulf food (“Genome: Physarum Polycephalum”). At critical conditions, it survives by producing a sexual fruiting structure that through meiosis produces walled spores which germinates and releases amoeboid or flagellated cells that can fuse to produce a zygote in thriving conditions (Sandgren et. al., 6). Its vital role in the environment is to decompose organic matter in temperate and deciduous forest thus it can mostly be found in the shady and damp areas of the forests (“Genome: Physarum Polycephalum”). Not only is this organism important in the environment but since the 1960s, it has been used in the study of cell and developmental biology such as cell differentiation, cell fusion, cell cycle regulation, DNA replication and a lot more (Schaap, et al.,). It has even been recently used in studies in Biophysics, the biosensory control of robots, unconventional computing in pathfinding or even on the generation of music (Schaap, et al.). Measuring growth is a basic method used in Microbiology (Ullmman, 371). Growth is defined as having added body substance in an organism which results to an increase in size (Indge 118). This can usually be measured through its growth rate wherein the amount of growth is observed in a specified period of time (Indge 118). This paper will try to study the effect of light on Physarum polycephalum by examining its growth. The organism thrives in shady areas thus the light will have a negative effect on its growth. If the organism is put in a lighted area, then it will only have minimum growth. The accuracy of the above hypothesis will be determined at the end of this paper. METHODS The initial part of the procedure of the experiment was taken from the B...