ABSTRACT
One of the major discoveries in modem biology is the remarkable cellular and molecular similarity of life on Earth in all its diverse forms. However, addition of betaine with high urea partly or fully restored normal growth, in accordance with the counteracting hypothesis. A large number of different carbohydrate osmolytes are known, including monosaccharides, disaccharides such as sucrose, heterosides, linear polyols with three to six carbons, and cyclic polyols. The major evolutionary question is, of course, why osmolytes are constrained by natural selection to a few solute types, mostly metabolically costly organic compounds, with the inorganic ions usually disfavored. Examination of a wide variety of biological processes in vitro have shown a widespread sensitivity to changes in inorganic ion concentration. Independently of biologists working on functional compatibility of cell osmolytes, biochemists had found as early as 1929 that sugars and polyols exhibit another widespread property: the ability to stabilize macromolecular structure under extreme conditions.
