- Adaptation
Adaptation occurs when a stimulus that once elicited a particular response, now elicits the opposite reaction. In C. elegans, this behavior has been shown through chemotaxis studies where extended exposure to an odor in the absence of food will result in a suppression of the chemotaxis response. In addition, by coupling an attractive stimulus to a starvation environment, the once attractive chemical is responded to as a repellent. However, these adaptations can be restored by brief exposure to the stimulus in the presence of food.
- Cell death
The death of a cell is a highly regulated process that occurs frequently throughout development. Current research shows that there are four different ways a cell can die, programmed cell death, necrosis, autophagy, and cytotoxic cell death. Research in C. elegans pioneered the discovery of the molecular pathway responsible for programmed cell death. More recent work using this model organism has made headways into elucidating the genes involved in regulating and impacting these other methods of cell death. There is controversy as to whether or not cell death by autophagy has been observed in C. elegans animals; however, an aspect of autophagy, macroautophagy, has been reported.
- Ceramide biosynthesis
Ceramides are essential to animal development. Depletion of ceramides by completely eliminating the key enzymes in the ceramide synthesis pathway results in larval lethality.
- Intestine development
The C. elegans intestine is attached to the posterior pharynx and extends the length of the worm, ending at the rectum. This major organ of the worm consists of 20 large, polyploid epithelial cells arranged in pairs, forming a tube. The intestine is responsible for food digestion, nutrient absorption, and synthesizing and storing macromomlecules such as fat droplets and birefringent gut granules. The intestine also plays major roles in the rhythmic behavior of the defecation cycle as well as stress responses and lifespan.
- Muscular system development and organization
The coordinated specification and functional assemblage of cells and tissues into the contractile organ system in the animal. C. elegans muscles are of two types: single sarcomere with focal attachment points at the ends (alimentary system and sex muscles) and obliquely striated muscles with many sarcomeres and no one substantial focal attachment point (body-wall muscles). Components of C. elegans muscles are similar to other animals and include heavy and light-chain myosin, actin, tropomyosin, troponin-like proteins, and paramyosin. Unlike other muscle systems, C. elegans muscles send neuron-like processes to neuropils that contain motor neuron axons rather than motor neurons sending axons to innervate the muscle. Contractile tissue is found throughout C. elegans and is required for locomotion (body wall muscle), eating (pharyngeal muscle), egg laying (vulval and uterine muscles, and gonad sheath), male mating (male tail muscles), and defecation (enteric muscles).
- Necrosis
Necrosis and apoptosis are contrasting modes of cell death. Whereas apoptotic cell death is associated with development and characterised by distinct stages of cell disassembly and engulfment, necrotic cell death is not a programmed cell fate and is characterised by an catastrophic disruption of the plasma membrane. Necrotic cell death is an important response to and in some cases, defense mechanism of, environmental or viral/bacterial pathogen assault.
- Neurotransmission
Neurons communicate across synaptic junctions with target cells, such as neurons, muscles, or specialized secretory cells through chemical messengers that are released from the neuron and bind to and activate receptors on the target cell. Pre-synaptic release of neurotransmitters can be evoked, such as through mechanical or chemical stimulation, as well as can occur spontaneously at a low rate. Depending on the neurotransmitter released and or the receptors of the post-synaptic cell, the activation of receptors can trigger excitatory or inhibitory actions in the target cell. These neuronal communications can also result in short term post-synapatic cellular changes to the membrane potential or can cause the activation of signaling cascades, resulting in longer term changes in the cell.