Wharton D A, To N B
Department of Zoology, University of Otago, Dunedin, New Zealand.
J Comp Physiol B. 1996;166(5):344-9. doi: 10.1007/BF02439922.
The freezing and freezing survival of the Antarctic nematode Panagrolaimus davidi after exposure to solutions of different osmotic concentrations has been examined using a thermoelectric cooling stage and multi-specimen cooling block to see if there is any evidence that freeze-induced desiccation prevents inoculative freezing. The nematodes froze in all the test solutions used (up to 1138 mosmol.l-1) and at all cooling rates and nucleation temperatures tested. Freezing survival was at its maximum in 0.1 mol.l-1 NaCl in artificial tap water after 1 h exposure to the test solution and in artificial tap water after 24 h exposure. Hyperosmotic and hyposmotic stress adversely affected the nematodes' ability to survive freezing. In nonfrozen controls survival declined with increasing osmolality of the test solution. Measurements of the osmolality of water extracted from a variety of moss samples indicate that the nematodes are exposed to an osmotic concentration of about 9 mosmol.l-1 in their natural habitat. This is close to that of artificial tap water. Our experiments, and measurements of freeze concentration effects in the literature, indicate that freeze-induced desiccation is unlikely to prevent inoculative freezing and the survival of nematodes over the winter.
利用热电冷却台和多样本冷却块，研究了南极线虫大卫泛裸囊线虫暴露于不同渗透浓度溶液后的冷冻及冷冻存活情况，以确定是否有证据表明冷冻诱导的干燥会阻止接种性冷冻。线虫在所有使用的测试溶液（高达1138 mosmol·l-1）中以及在所有测试的冷却速率和成核温度下都会冷冻。在接触测试溶液1小时后，于含0.1 mol·l-1 NaCl的人工自来水中，以及接触24小时后于人工自来水中，冷冻存活率最高。高渗和低渗胁迫均会对该线虫的冷冻存活能力产生不利影响。在未冷冻的对照中，存活率会随着测试溶液渗透压的增加而下降。对从各种苔藓样本中提取的水的渗透压测量表明，该线虫在其自然栖息地中所接触的渗透浓度约为9 mosmol·l-1。这与人工自来水相近。我们的实验以及文献中对冷冻浓缩效应的测量表明，冷冻诱导的干燥不太可能阻止接种性冷冻以及线虫越冬存活。
