Isothermal microcalorimetry allows detection of 'aquaporines' in quinoa seeds

Aquaporines are channels specifically involved in the overall transport of water through plasma membrane and tonoplast cells. In order to test their p resence in quinoa (Chenopodium quinoa Willd.) seeds, we used isothermal mic rocalorimetry to monitor germination and root elongation processes. Measure ments were made in the presence of distilled water or HgCl2 solution, which inhibits the function of aquaporines. When the seeds were allowed to take up water in the presence of the mercury salt, lower values were found for t he specific thermal power, from the beginning of the process, as compared w ith results of the control experiments. The inhibition by the mercurial sol ution was reverted by EDTA and thiourea solutions. (C) 2000 Elsevier Scienc e B.V. All rights reserved.