ER-associated degradation
Correctly folding proteins is a severely complicated process. Within eukaryotes an optimal environment for protein folding is provided by the endoplasmic reticulum (ER). In addition, proper folding requires the activity of numerous molecular chaperones and folding enzymes. Despite the controlled environment and numerous molecular helpers, misfolded proteins do sometimes occur. ER-associated degradation (ERAD) is a normal cell function that detects and deals with these occurrences. Through the ERAD process, misfolded proteins are recognized, retrotranslocated to the cytosol, ubiquinated, and then degraded by the proteosome.
Defecation
In C. elegans the expulsion of intestinal contents occurs every 45-50 seconds. This cycle is characterized by a pattern of muscle contractions under both muscle and neuronal control. The steps of the defecation cycle are a posterior body contraction (pBoc), an anterior body contraction (aBoc), and the final expulsion step (Exp) where the enteric muscles contract, opening the anus and allowing the intestinal contents to be released. Each step is independently controlled as mutations exist that affect one step but do not alter the timing or occurrence of the other. Further, Ca++ oscillations in the intestine, rather than neuronal stimulation, have been shown to control the initiating pBoc step. The contractions of the enteric muscles are controlled by GABA motor neurons AVL and DVB through an excitatory GABA-gated cation channel. The periodicity of the cycle is influenced by the presence of food, is temperature compensated, and can be reset by mechanosensory input.