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.

RNA splicing

During pre-messenger RNA (pre-mrRNA) processing, cis-splicing reactions remove non-coding introns and joins coding exons. The majority of splicing is catalyzed by spliceosomes, large RNA-protein complexes composed of small nuclear ribonucleoproteins (snRNPs) that recognize splice donor and acceptor sites within the nascent RNA strand. Alternative mRNAs for a given gene can be created during the splicing reactions through varying the degree of cutting and splicing of introns and exons guided by alternative splice sites. C. elegans also exhibits trans-splicing where sequences from different primary RNA transcripts are used to make the mRNA. In C. elegans, ~70% of transcripts are trans-spliced with either a splice leader sequence SL1 or SL2 joined to the final transcript. Splice leaders are important

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.