- Dosage compensation
A mechanism for regulating chromosome-wide gene expression based on the ratio of autosomes to sex chromosomes. In C. elegans, the hermaphrodite is XX with two X chromosomes while the male is X0 with only one X chromosome. Dosage compensation machinery in these nematodes reduces expression of genes on both X chromosomes in the hermaphrodite.
- Molting
Under good conditions, C. elegans enters and exits four larval stages before becoming a fertile adult. Each developmental stage is punctuated with a molt that entails the shedding of the larval cuticle and the generation of a completely new one. It has been shown that each cuticle is unique in its composition. Molting is a carefully timed process that needs to be coordinated with development, new cuticle synthesis, and cuticle shedding. Mutations in a set of genes called heterochronic genes regulates the timing development and the molts and result in precocious or retarded development of parts of the animals that aren't synchronized with the animals' life stage.
- Gap junction biogenesis and organization
Gap junctions, along with chemical synapses, mediate communication between neurons. Innexins are major components of these junctions. Gap junctions can be identified in electron micrographs as parallel membranes of closely apposed cells.
- Autophagy
Autophagy is the degradation of cytoplasmic components through an autophagolysosome (autolysosome). Of the many types of autophagy in nature, macroautophagy, which involves the sequestration of cellular material by a double-membrane autophagosome, has been observed in C. elegans. The steps in this degradation process include nucleation of vesicle formation, expansion of the membrane with concomitant capture of cellular components (vesicle elongation), autophagolysosome or autolysosome, formation (autophagosome fusion with lysosome), and completion (vesicle breakdown and the lysis of the captured cytoplasmic material).
- P granule biogenesis and organization
Germ granule proteins are found among a wide variety of species. In C. elegans, these granules are known as P granules. They are initially seen in the cytoplasm of oocytes and early embryos. In early embryogenesis they are asymmetrically segregated into blastomeres that eventually give rise to the germ line. In adults, P granules are peri-nuclear and cluster with nuclear pore complexes. They are associated with RNA metabolism and appear to play a role in nascent mRNA release from the nucleus.
- Recombination
The process in which genetic material is exchanged, either between different chromosomes or different regions between the same chromosome, to result in a combination of genetic material different from the starting genotypes. Defects in recombination processes can lead to alterations in the proper segregation of genetic material to daughter nuclei. In C. elegans the rate of recombination was shown to be inversely affected by hermaphrodite age and temperature. Recombination rates decrease with age of the hermaphrodite and increase with temperature.
- Cuticle biogenesis
The C. elegans cuticle is a protective exoskeleton of specialized extracellular matrix (ECM) consisting primarily of collagen, lipids, and glycoproteins and is required for viability. (Chisholm and Hardin 2005; Page and Johnstone 2007). The cuticle determines the shape of the body and, through connection from the epidermis to muscle, provides anchoring points for muscle contraction. The cuticle also serves as a model for ECM formation and function with molecules and pathways involved in cuticle biogenesis conserved in vertebrates (Page and Johnstone 2007). The outer epithelial layer, the epidermis, of the embryo undergoes a series of cell fusions to make large multinucleate, or syncytial, epidermal cells, which secrete the materials needed to make up the cuticle. This protective layer is produced five times during C. elegans development, with each molt ending with an entirely new cuticle.
- DNA damage response
DNA damage can occur during normal recombination events or result from various insults, such as exposure to chemical mutagens or exposure to radiation. Metazoans have evolved mechanisms to detect, assess, and deal with any damage at specific checkpoints during the cell cycle. Studies in yeasts and mammals have identified several genes that are required for proper activation of cell cycle check-points following various types of DNA damage. However, in these metazoans, DNA damage can induce apoptosis as well. The inability to efficiently repair DNA damage or remove cells with severely damaged genomes has been linked to several human cancers.
- Apoptotic DNA degragdation
DNA degadation is a distinct process during cell death that proceeds simultaneously with cell corpse engulfment. Apoptotic DNA degradation has been proposed to require a multi-nuclease complex, the degadeosome, which is composed of nucleases (CPS-6, CRN-1, CRN-4, CRN-5, CYP-13), and mitochondiral nonnuclease components such as WAH-1.
- Signal transduction
Signal transduction begins with a stimulating event, such as a ligand binding to a receptor on the surface of the cell, and is followed by intracellular signaling steps that eventually trigger a response. In many cases the end response is modification of the regulation of gene transcription, but could also be the regulation of a metabolic process.