Plant Biology

A Pinch of Salt

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Science  26 Jul 2002:
Vol. 297, Issue 5581, pp. 481
DOI: 10.1126/science.297.5581.481a

The unicellular green alga Dunaliella salina shows remarkable ability to tolerate salt, being able to grow in the presence of as much as 3.5 M NaCl. Among the adjustments the cells make in response to changing osmotic pressure are to adjust internal glycerol concentration and to transcribe certain salt-inducible genes. Azachi et al., analyzing one of the salt-inducible mRNAs, find that a microsomal enzyme is added to the mix as the cells adjust to higher salinities. Osmotic shock alone is not as effective as salt at inducing synthesis of this enzyme. The enzyme, kcs, catalyzes the first rate-limiting step in fatty acid elongation. Cells grown in higher salt concentrations show a shift in membrane composition of microsomes from C16 toward C18 fatty acids as well as an increase in desaturation of the fatty acids. These modifications in membrane composition may serve to adjust to altered dynamics of vesicle transport and membrane fusion in the osmotically accommodated cytoplasmic environment. — PJH

Plant Physiol.129, 1320 (2002).

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