The California (LGCA) and Butte Sink (LGBS) strains of the sterol auxotrophic fungus Lagenidium giganteum (Oomycetes: Lagenidiales) enter the sexual cycle on media supplemented with sterols.
http://spaces.wikiprofessional.org/spaces/conceptNavigator%3FknowletId%3Dumls/C1080933
Sterols, or steroid alcohols are a subgroup of steroids with a hydroxyl group at the 3-position of the A-ring.[1] They are amphipathic lipids synthesized from acetyl-coenzyme A via the HMG-CoA reductase pathway. The overall molecule is quite flat. The hydroxyl group on the A ring is polar. The rest of the aliphatic chain is non-polar.
Sterols of plants are called phytosterols and sterols of animals are called zoosterols. Important zoosterols are cholesterol and some steroid hormones; notable phytosterols include campesterol, sitosterol, and stigmasterol. Ergosterol is a sterol present in the cell membrane of fungi, where it serves a role similar to cholesterol in animal cells.
Sterols and related compounds play essential roles in the physiology of eukaryotic organisms. For example, cholesterol forms part of the cellular membrane in animals, where it affects the cell membrane's fluidity and serves as secondary messenger in developmental signaling. In humans and other animals, corticosteroids, such as cortisol act as signalling compounds in cellular communication and general metabolism.
Phytosterols may block cholesterol absorption sites in the human intestine thus helping to reduce cholesterol in humans.http://en.wikipedia.org/wiki/Sterol
Animals, plants, fungi, and protists are eukaryotes (IPA: /juːˈkærɪɒt/ or IPA: /-oʊt/), organisms whose cells are organized into complex structures enclosed within membranes. The defining membrane-bound structure which differentiates eukaryotic cells from prokaryotic cells is the nucleus. The presence of a nucleus gives these organisms their name, which comes from the Greek ευ (eu), meaning "good/true", and κάρυον (karyon), "nut". Many eukaryotic cells contain other membrane-bound organelles such as mitochondria, chloroplasts and Golgi bodies.
Cell division in eukaryotes is different from organisms without a nucleus (prokaryotes). It involves separating the duplicated chromosomes, through movements directed by microtubules. There are two types of division processes. In mitosis, one cell divides to produce two genetically-identical cells. In meiosis, which is required in sexual reproduction, one diploid cell (having two instances of each chromosome, one from each parent) undergoes recombination of each pair of parental chromosomes, and then two stages of cell division, resulting in four haploid cells (gametes). Each gamete has just one complement of chromosomes, each a unique mix of the corresponding pair of parental chromosomes.
Eukaryotes appear to be monophyletic, and so make up one of the three domains of life. The two other domains, bacteria and archaea, are prokaryotes, and have none of the above features. But eukaryotes do share some aspects of their biochemistry with archaea, and so are grouped with archaea in the clade Neomura.
http://en.wikipedia.org/wiki/Eukaryote
