The chemical reactions and pathways resulting in the breakdown of choline (2-hydroxyethyltrimethylammonium), an amino alcohol that occurs widely in living organisms as a constituent of certain types of phospholipids and in the neurotransmitter acetylcholine.

Any process that mediates the transfer of information from one cell to another. This process includes signal transduction in the receiving cell and, where applicable, release of a ligand and any processes that actively facilitate its transport and presentation to the receiving cell. Examples include signaling via soluble ligands, via cell adhesion molecules and via gap junctions.

The process whose specific outcome is the progression of the embryo sac over time, from its formation to the mature structure. The process begins with the meiosis of the megasporocyte to form four haploid megaspores. Three of the megaspores disintegrate, and the fourth undergoes mitosis giving rise to a binucleate syncytial embryo sac. The two haploid nuclei migrate to the opposite poles of the embryo sac and then undergo two rounds of mitosis generating four haploid nuclei at each pole. One nucleus from each set of four migrates to the center of the cell. Cellularization occurs, resulting in an eight-nucleate seven-celled structure. This structure contains two synergid cells and an egg cell at the micropylar end, and three antipodal cells at the other end. A binucleate endosperm mother cell is formed at the center. The two polar nuclei fuse resulting in a mononucleate diploid endosperm mother cell. The three antipodal cells degenerate.

A fatty acid oxidation process in which the methyl group at the end of the fatty acid molecule (the omega carbon) is first oxidized to a hydroxyl group, then to an oxo group, and finally to a carboxyl group. The long chain dicarboxylates derived from omega-oxidation then enter the beta-oxidation pathway for further degradation.

The chemical reactions and pathways involving nitriles, an organic compound containing trivalent nitrogen attached to one carbon atom. The nitriles are named with reference to the acids produced by their decomposition; for example, hydrocyanic acid is formic nitrile, and methyl cyanide is acetic nitrile.

The space external to the outermost structure of a cell. For cells without external protective or external encapsulating structures this refers to space outside of the plasma membrane. This term covers the host cell environment outside an intracellular parasite.