Biochemistry

Surviving a Dry Spell

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Science  20 Jul 2007:
Vol. 317, Issue 5836, pp. 296
DOI: 10.1126/science.317.5836.296c

Life (as we know it) is based on carbon, and one fortuitous factor is the compatibility of sugars and water. Glucose is readily soluble (at much higher concentrations than the building blocks of other biological polymers), easily handled by enzymes via its chemical functionalities, and benign (and perhaps even beneficial) in its interactions with other biochemicals. In considering the major circulating sugar in insects—trehalose, which is a head-to-head dimer of glucose—the extraordinary tolerance of Polypedilum vanderplanki larvae to dessication comes to mind. When the rock pools where these larvae live dry up, the larval fat body synthesizes trehalose and releases it into the hemolymph in order to protect tissue constituents as water is lost. When water becomes available again, dehydrated larvae undergo rehydration and resume their developmental progression into adult midges. Kikawada et al. have identified a trehalose transporter (called TRET1) in P. vanderplanki. They show that it is specific for trehalose versus maltose, sucrose, and lactose; they also show that it functions as a low-affinity, high-capacity facilitated transporter that can be expressed benignly in mammalian cells. — GJC

Proc. Natl. Acad. Sci. U.S.A. 104, 11585 (2007).

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