ALTRUISTIC AMOEBAE (Syllabus: GS Paper 3 – Sci and Tech)

Context: Scientists have recently gained valuable new insights into natural altruism by studying the amoeba Dictyostelium discoideum.

Altruistic amoebae

• About: It is a free-living, fast-growing, unicellular amoeba.
• Habitat and Feeding: In the wild, it feeds on bacteria that grow on decaying vegetation.
• Formation of Multicellular Aggregates: When bacteria run out, the amoebae stop multiplying and gather in the hundreds of thousands to form multicellular aggregates visible to the naked eye.
• Transformation into Fruiting Bodies: The aggregates transform into fruiting bodies, each a few millimetres tall.

oA fruiting body is composed of a slender stalk made of dead cells and holds aloft a droplet of spores.

• tgrB1 and tgrC1: These genes are located next to each other in the D. discoideum genome, and are expressed together (so if one isn’t expressed, the other isn’t either).

oThey contain information for cells to make two cell surface proteins called TgrB1 and TgrC1.  

oThe TgrB1 protein on one cell binds to the TgrC1 protein on another. 

Altruism

• Origin: The term ‘altruism’ was coined by French philosopher and sociologist Auguste Comte.
• Etymology: It is derived from the Italian word ‘altrui’, meaning “to others” or “of others”.
• Definition: It refers to the unselfish concern or act of an individual, group, or organization which is done to serve the needs, interests, and wellness of others.