Opsin three domains of life: Archaea, Bacteria, and Eukaryota. In Eukaryota, type I opsins are found mainly in unicellular organisms such as green algae, and in fungi. In most complex multicellular eukaryotes, type I opsins have been replaced with other light-sensitive molecules such as cryptochrome and phytochrome in plants, and type II opsins in Metazoa (animals). Microbial opsins are often known by the rhodopsin form of the molecule, i.e., rhodopsin (in the broad sense) = opsin + chromophore. Among the many kinds of microbial opsins are the proton pumps bacteriorhodopsin (BR) and xanthorhodopsin (xR), the chloride pump halorhodopsin (HR) the photosensors
International Code of Nomenclature for algae, fungi, and plants International Botanical Congress have produced revised versions of these "Rules", later called the "International Code of Botanical Nomenclature", and then "International Code of Nomenclature for algae, fungi, and plants". The Nomenclature Section of the 18th International Botanical Congress in Melbourne, Australia (2011) made major changes: Some important versions are listed below. Specific to botany More general International Code of Nomenclature for algae, fungi, and plants The International Code of Nomenclature for algae, fungi, and plants (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups