Question

If a cell gained a gene that allowed it to produce more or different compatible solutes, what environments could it live in better?

Answer 1

Compatible solutes or osmoprotectants are compounds that accumulate in cytoplasm when there is a drought condition. They are non-toxic to the cells. They include sugars like sucrose, hexose, trehalose; sugar alcohols including cyclic polyols; glycine and betaine; and amino acids( proline). They are involved in adjustment of osmotic environment, scavenging ROS, stabilize proteins/cell membranes. They also help metabolic pathways pathways to adapt.

If a cell acquires a gene for synthesizing one or more compatible solutes, then it can grow in an environment where there is water deprivation. As it will help to balance external osmotic pressure, the cell could now live in low water conditions. These cells can live in high salt concentration, as they will be halotoolerant or halophillic. Solute glycine betaine (GB) can help a cell tolerate extreme salinity, low water conditions (drought) as well as extreme temperature (cold).Water stress is eliminated by compatible solutes the elevating the osmotic pressure in the cell. Taurine is produced during dehydration by mammalian cell by possibly acting as antioxidant, a calcium modulator, a synaptic neuromodulator, and a membrane stabilizer.

Osmolytes can also be produced during anhydrobiosis, wherein the organisms enter an extremely dehydrated dormant state or when exposed to hydrostatic pressure. Some osmolytes are antioxidants. Hypotaurine found in mammalian reproductive fluids, protects sperm and eggs from oxygen radicals. Glycerol and proline may help in redox balance by regenerating NADH during anerobic respiration. Stress induced dormancy can be overcome by producing glucose and trehalose. Thus, other environments that the cell producing compatible solutes can live in better is environments with high reactive oxygen species, reduced redox balance, low osmotic pressure, high hydrostatic pressure etc.