Jagdale G B, Grewal P S
Department of Entomology, Ohio State University, Ohio Agricultural Research and Development Center, 1680 Madison Avenue, Wooster, OH 44691, USA.
Int J Parasitol. 2003 Feb;33(2):145-52. doi: 10.1016/s0020-7519(02)00257-6.
The effect of thermal acclimation on trehalose accumulation and the acquisition of thermotolerance was studied in three species of entomopathogenic nematodes adapted to either cold or warm temperatures. All three Steinernema species accumulated trehalose when acclimated at either 5 or 35 degrees C, but the amount of trehalose accumulation differed by species and temperature. The trehalose content of the cold adapted Steinernema feltiae increased by 350 and 182%, of intermediate Steinernema carpocapsae by 146 and 122% and of warm adapted Steinernema riobrave by 30 and 87% over the initial level (18.25, 27.24 and 23.97 microg trehalose/mg dry weight, respectively) during acclimation at 5 and 35 degrees C, respectively. Warm and cold acclimation enhanced heat (40 degrees C for 8h) and freezing (-20 degrees C for 4h) tolerance of S. carpocapsae and the enhanced tolerance was positively correlated with the increased trehalose levels. Warm and cold acclimation also enhanced heat but not freezing tolerance of S. feltiae and the enhanced heat tolerance was positively correlated with the increased trehalose levels. In contrast, warm and cold acclimation enhanced the freezing but not heat tolerance of S. riobrave, and increased freezing tolerance of only warm acclimated S. riobrave was positively correlated with the increased trehalose levels. The effect of acclimation on maintenance of original virulence by either heat or freeze stressed nematodes against the wax moth Galleria mellonella larvae was temperature dependent and differed among species. During freezing stress, both cold and warm acclimated S. carpocapsae (84%) and during heat stress, only warm acclimated S. carpocapsae (95%) maintained significantly higher original virulence than the non-acclimated (36 and 47%, respectively) nematodes. Both cold and warm acclimated S. feltiae maintained significantly higher original virulence (69%) than the non-acclimated S. feltiae (0%) during heat but not freezing stress. In contrast, both warm and cold acclimated S. riobrave maintained significantly higher virulence (41%) than the non-acclimated (14%) nematodes during freezing, but not during heat stress. Our data indicate that trehalose accumulation is not only a cold associated phenomenon but is a general response of nematodes to thermal stress. However, the extent of enhanced thermal stress tolerance conferred by the accumulated trehalose differs with nematode species.
研究了热驯化对三种适应低温或高温的昆虫病原线虫海藻糖积累和耐热性获得的影响。当在5℃或35℃下驯化时，所有三种斯氏线虫属线虫都会积累海藻糖，但海藻糖积累量因物种和温度而异。适应低温的斯氏小卷蛾线虫海藻糖含量在5℃和35℃驯化期间，相对于初始水平（分别为18.25、27.24和23.97微克海藻糖/毫克干重）分别增加了350%和182%，中间型的苹果蠹蛾斯氏线虫增加了146%和122%，适应高温的里奥勇敢斯氏线虫增加了30%和87%。高温和低温驯化增强了苹果蠹蛾斯氏线虫对热（40℃处理8小时）和冷冻（-20℃处理4小时）的耐受性，且增强的耐受性与海藻糖水平的增加呈正相关。高温和低温驯化也增强了斯氏小卷蛾线虫的耐热性，但未增强其耐冻性，增强的耐热性与海藻糖水平的增加呈正相关。相反，高温和低温驯化增强了里奥勇敢斯氏线虫的耐冻性，但未增强其耐热性，仅高温驯化的里奥勇敢斯氏线虫增加的耐冻性与海藻糖水平的增加呈正相关。驯化对热应激或冻应激线虫对大蜡螟幼虫的原始毒力维持的影响取决于温度，且因物种而异。在冷冻应激期间，低温和高温驯化的苹果蠹蛾斯氏线虫（84%），在热应激期间，只有高温驯化的苹果蠹蛾斯氏线虫（95%）维持的原始毒力显著高于未驯化的线虫（分别为36%和47%）。在热应激而非冷冻应激期间，低温和高温驯化的斯氏小卷蛾线虫维持的原始毒力（69%）均显著高于未驯化的斯氏小卷蛾线虫（0%）。相反，在冷冻应激而非热应激期间，高温和低温驯化的里奥勇敢斯氏线虫维持的毒力（41%）均显著高于未驯化的线虫（14%）。我们的数据表明，海藻糖积累不仅是一种与寒冷相关的现象，而且是线虫对热应激的普遍反应。然而，积累的海藻糖赋予的热应激耐受性增强程度因线虫物种而异。
