Holoaden Holoaden Holoaden (common name: highland frogs) is a small genus of craugastorid frogs endemic to southeastern Brazil. "Holoaden" is the type genus of subfamily Holoadeninae that was erected in 2008 and placed in family Strabomantidae, erected at the same time. Before that, it was in Brachycephalidae. However, later research has led the whole Strabomantidae, Holoadeninae included, to become included in Craugastoridae. This arrangement is not followed by all, and the AmphibiaWeb still keeps Holoadeninae, and consequently "Holoaden", in Strabomantidae. "Holoaden" grow to snout–vent length at most. Head is narrower than the body. Differentiated tympanic membrane and tympanic annulus are absent.
Biological membrane fatty acid composition in accordance with differing temperatures. In animal cells, membrane fluidity is modulated by the inclusion of the sterol cholesterol. This molecule is present in especially large amounts in the plasma membrane, where it constitutes approximately 20% of the lipids in the membrane by weight. Because cholesterol molecules are short and rigid, they fill the spaces between neighboring phospholipid molecules left by the kinks in their unsaturated hydrocarbon tails. In this way, cholesterol tends to stiffen the bilayer, making it more rigid and less permeable. For all cells, membrane fluidity is important for many reasons. It enables membrane