Dictyostelium discoideum Sample Clauses

Dictyostelium discoideum. ‌ Dictyostelium discoideum is a single celled organism that can, when environmental conditions deteriorate, aggregate into a multicelled structure called a pseudoplas- modium or a slug. This pseudoplasmodium gains the ability to sense heat and light in order to guide itself towards the soil surface where it transforms into a fruiting body bearing stalk that releases spores. Taken away by the wind or passing animals, these spores are allowed to germinate in more favourable regions. The first person that became fascinated by these organisms was the German botanist Xxxxx Xxxxxxx. In 1869 he carefully described the process of cellular ag- gregation and culmination into a spore containing fruiting body. About 80 years later, in 1946, Xxxx Xxxxx Xxxxxx showed (using axenically growing mutants) that he could manipulate the characteristic aggregation process by creating a flow in the cell medium. His experiments proved the involvement of a chemical substance in the directional movement that leads to cell aggregation. With this discovery Xxxxxx paved the road towards extensive research in the area of chemotaxis. This process, in which cells compute the direction of a concentration gradient and initiate directional movement based on this computation, plays a role in many cellular behaviors criti- cal to the existence of multi-cellular organisms. Examples include: embryogenesis, wound healing and the detection of infection by the immune system. The discov- ery of cyclic adenosine mono-phosphate (cAMP) as the chemoattractant that Xxxxxx proposed by Xxxxxx and others in 1967 [51] lead to a more systematic way of inves- tigating the phenomenon. Since the advent of molecular biology, a lot has become clear as to how these cells can sense and move directionally towards cAMP sources. The publication of the genome [20] meant that many unknown factors could be eas- ily identified and investigated using knockout techniques. Moreover, the discovery of green fluorescent protein (GFP) technology and its straightforward application in D. Discoideum combined with high gene sequence homology to higher eukaryotes has made it an immensely popular model organism for the study of chemotaxis.