Title
Vitrification is essential for anhydrobiosis in an African chironomid, Polypedilum vanderplanki
Author
Minoru Sakurai, Takao Furuki, Ken-ichi Akao, Daisuke Tanaka, Yuichi Nakahara, Takahiro Kikawada, Masahiko Watanae, and Takashi Okuda
Year
2007
Journal
Proceedings of the National Academy of Sciences of the United States of America
Abstract
Anhydrobiosis is an extremely dehydrated state in which organisms show no detectable metabolism but retain the ability to revive after rehydration. Thus far, two hypotheses have been proposed to explain how cells are protected during dehydration: (i) water replacement by compatible solutes and (ii) vitrification. The present study provides direct physiological and physicochemical evidence for these hypotheses in an African chironomid, Polypedilum vanderplanki, which is the largest multicellular animal capable of anhydrobiosis. Differential scanning calorimetry measurements and Fourier-transform infrared (FTIR) analyses indicated that the anhydrobiotic larvae were in a glassy state up to as high as 65°C. Changing from the glassy to the rubbery state by either heating or allowing slight moisture uptake greatly decreased the survival rate of dehydrated larvae. In addition, FTIR spectra showed that sugars formed hydrogen bonds with phospholipids and that membranes remained in the liquid-crystalline state in the anhydrobiotic larvae. These results indicate that larvae of P. vanderplanki survive extreme dehydration by replacing the normal intracellular medium with a biological glass. When entering anhydrobiosis, P. vanderplanki accumulated nonreducing disaccharide trehalose that was uniformly distributed throughout the dehydrated body by FTIR microscopic mapping image. Therefore, we assume that trehalose plays important roles in water replacement and intracellular glass formation, although other compounds are surely involved in these phenomena.
Full Article
Instrument
IMV-4000/FTIR-6200
Keywords
FTIR Microscopy, trehalose, water replacement, Fourier-transform infrared microspectroscopy, biological glass, cryptobiosis