C. elegens "Smell/Taste"

 

 

Much of the nervous system and more than 5% of  DNA genes of C. elegens are devoted to the recognition of environmental chemicals. A total of 32 sensory cells detect the chemicals in its environment. These 32 cells have surface monitors that detect molecules outside the cell and activate cellular responses to some 500 to 1000 different chemicals. Which chemicals are detected and what responses are signaled are determined by different DNA genes.The signals create perception of external chemical cues, including odorants, tastants, and pheromones, into information that drives attraction or avoidance motor programs. It uses this chemosensation to find food, avoid noxious conditions, develop appropriately, and mate.

The electron micrograpm shown above is that of the 6-celled "lip" that surround the mouth of C.elegens showing the dendritic chemosensory sensory cilia in the cells in the "lip".

 Chemotaxis of C. elegans to some cations, anions, cyclic nucleotides, and amino acids have been observed by experiment. Detection of most, such as sodium and chlorine ions (table salt in water), are also detected by humans. They too are attracted to diacetyl that produces that buttery smell/taste flavor of popcorn and trimethylthiazole, the result of the Maillard process, producing the pleasant smells of  a searing steak and freshly baked cookies and bread. 

And like human, C. elegens differentiate chemicals as either attractive or repellent. Sodium dodecyl sulfate is a surfactant (surface active agent) or kind of soap, which is repulsive to C. elegens. Humans are repelled by it also because it produces a bitter taste and rancid smell (which is why bath soaps are always scented). It is also toxic to both C. elegens and humans in high consecrations.

And so it is that at the atomic level in DNA the first signs of an attraction for pleasure and avoidance of pain first appears which, with the development of the amygdala in animals, ultimately gives rise to the qualia of emotions of pleasure and pain.