In This Issue

PNAS u December 18, 2012 u vol. 109 u no. 51 u 20775–20776 www.pnas.org/cgi/doi/10.1073/iti5112109 Water is considered essential for active life, but some organisms can survive severe desiccation for extended periods by expressing various protective proteins such as late embryogenesis abundant (LEA) proteins. Shumin Li et al. (pp. 20859–20864) engineered a human liver cancer cell line to express LEA2 or LEA3, both of which are naturally found in brine shrimp embryos, and investigated whether either protein protected the cells against desiccation. Because many desiccation-tolerant organisms also accumulate low molecular weight solutes— such as the sugar trehalose, which protects cells against osmotic stress during desiccation—the authors also engineered the cells to express trehalose transporter (TRET1) to enable trehalose uptake. Cells were incubated in medium containing trehalose prior to desiccation. The authors then immediately rehydrated the cells and examined membrane integrity by microscopy. In the absence of trehalose and LEA proteins, the authors found no membrane integrity, but cells that contained trehalose and expressed either LEA protein showed 98% integrity. Moreover, cells containing LEA3 and trehalose proliferated 18-fold after 7 days in culture, whereas nondried controls proliferated 27-fold; cells expressing LEA2 with or without trehalose proliferated more slowly. The findings may aid the development of strategies for long-term storage of desiccated cells, according to the authors. — N.Z. Engineering cultured human cells to survive desiccation