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Journal of Experimental Biology 155,629-641 (1991)
Published by Company of Biologists 1991

Cold-Tolerance Mechanisms of the Antarctic Nematode Panagrolaimus Davidi

D. A. WHARTON ¹ and I. M. BROWN ¹

¹ Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand

When free of surface water in air or liquid paraffin, the antarctic nematode Panagrolaimus davidi is freezing intolerant but avoids freezing by supercooling.

Survival of long-term exposure is enhanced by sub-zero temperatures compared with controls maintained at 99% relative humidity and 15°C.

In water the nematodes are seeded by exogenous ice nucleation and a proportion are freezing tolerant. Ice formation appears to be restricted to the pseudocbel.

The degree of freezing tolerance is dependent upon the age of the culture and its thermal history.

P. davidi is freezing tolerant when exposed to sub-zero temperatures in water and freezing intolerant when free of surface water and able to supercool. These two strategies are not mutually exclusive as they are often thought to be in arthropods.

Key words: nematode, antarctic, Panagrolaimus davidi, cold tolerance, freezing tolerance, freezing intolerance, ice nucleation

Accepted on September 6, 1990