Osmotic adaptation

Wyn Jones, R.G. (1984). Phytochemical aspects of osmotic adaptation. In Recent Advances in Phytochemistry 18, Phytochemical Adaptations to Stress, ed. B.N. Timmermann,K.C. SteelinandF. A. Loewns, pp. 55-78. New York Plenum Press. 

Singh, N.K., Bracket, C.A.S., Hasegawa, P.M., Handa, A.K., Bruckel, S., Hermondson, M.A., Pfankoch, E., Regnier, F.E. Bressan, R.A. (1987o). Characterisation of osmotin. A Thaumatin-like protein associated with osmotic adaptation in plant cells. Plant Physiology, 85, 528-36. 

Harms, C.T. Oertli, J.J. (1985). The use of osmotically adapted cell cultures to study salt tolerance in vitro. Journal of Plant Physiology, 120, 29-38. 

Figure 6.18. The three common elements in the osmosensory signal transduction cascade of cells (1) osmosensors that monitor osmolality (2) signal transduction pathways that transmit the information provided by the primary osmosensors to (3) osmotic response elements that regulate gene expression and activities of proteins (enzymes and transporters) that are essential for osmotic adaptation.

Plants as well as other organisms have evolved several adaptive strategies to counter these types of abiotic stresses (Csonka, 1989 Bohnert et al., 1995). At the cellular level, the most common type of osmotic adaptation is the accumulation of compatible solutes in the cytoplasm and the sequestration of NaCl into the vacuole (Rhodes and Hanson 1993 Bohnert et al., 1995). Compatible solutes arc small molecules that can act as nontoxic cytoplasmic osmolytes to raise osmotic pressure, and stabilize enzymes and membranes against damage by high salt levels (Wyn Jones, 1984). 

Rov 0-R Polyol Pathway The Biosynthesis of Streptomycin Osmotic Adaptation Genetic Diseases of Glycogen... 

It is not surprising that most of our knowledge on osmoadaptation in microorganisms comes from research conducted in mesophiles, and that little is known about the response to salt stress in thermophiles and hyperthermophiles. However, the same interest that fuels research into so many aspects of life at extremely high temperatures also fuels research into osmotic adaptation in thermophilic and hy-perthermophilic organisms, leading to the rapid increase in the knowledge of the compatible solutes themselves, their role in the protection of macromolecules, and the mechanisms of osmotic adaptation. 

Unlike Tc. litoralis, hyperthermophiles do not appear to uptake many osmolytes from the medium, resorting, in general, to the synthesis of specific compatible solutes such as cBPG, MG, DIP, and diglycerol phosphate. For example, P.furiosus resorts exclusively to de novo synthesis of MG for osmotic adaptation, and DIP... 

Several questions have already been answered regarding osmotic adaptation in organisms that live at high temperatures, hut many remain to be answered. It... 

The definite elucidation of the physiological role of compatible solutes in thermophiles and hyperthermophiles must await the development of suitable genetic tools. Compatible solutes in thermophiles and, particularly, in hyperthermophiles serve as excellent examples of evolutionary strategies developed to cope with adaptation to selective pressures, and their role in cell protection and their function in osmotic adaptation or thermal protection will, undoubtedly, lead to surprising new results. 

Borngen, K., Battle, A.R., Moker, N., Morbach, S. et al (2010) The properties and contribution of the Corynebacterium glutamicum MscS variant to fine-tuning of osmotic adaptation. Biochim. Biophys. Acta, 1798, 2141-2149. 

Dickson DM, Wyn Jones RG and Davenport J, 1980, Steady state osmotic adaption in ulva lactuca. Planta, 150, 158-165. 

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