Identification and characterization of ice nucleators transmitting from prey to predator

作为鉴定家蛛(Achaearanea Tepidaroirum)外源冰核物质的第一步，研究了冰核物质在捕食性动物(Porcellio Scaber)体内的定位及其热敏性。摄取等足类动物的肠道将蜘蛛的过冷却点从-5摄氏度提高到-9摄氏度，这一效果与猎物全身的效果相当。这意味着冰核至少存在于被捕食动物的消化道中，从而表明被捕食动物在进食过程中将它们结合在一起。以加热的等足类动物的肠道为食的蜘蛛的过冷却点低于那些以未加热的肠道为食的蜘蛛。因此，从猎物传递给捕食者的冰核对热很敏感，这表明它是起源于有机的。为了表征冰核的特征，研究了它们在野外的季节和地理丰度。我发现，从日本北部到南部，冰核全年都存在，地理范围很广。几乎所有野外采集的猎物动物，如蟋蟀、蚂蚁和等足类动物都含有它们。这些观测结果有力地表明，冰核从猎物向捕食者传播的现象在野外很常见。由于冰核的普遍存在，细菌等冰核活性微生物可以作为冰核的催化剂。

As the first step to identify the exgenous ice nucleators of the house spider, Achaearanea tepidaroirum, location of ice nucleators in the body of prey animals (Porcellio scaber) and its heat susceptibility were examined. Ingestion of the isopod's gut elevated the spider's supercooling point from -5 to -9C and this effect was comparable to that of whole body of the prey. This means that the ice nucleators exist at least in the alimentary canal of the prey animals, thus suggesting that the prey animals incorporate them in the process of feeding. Spiders that fed on a heated isopod's gut had a lower supercooling point than those fed on an unheated gut. Thus, the ice nucleators transmitting from prey to predator were susceptible to heat, thus suggesting that it is organic in origin.To characterize the ice nucleators, their seasonal and geographical abundance in the field was examined. I found that the ice nucleators occur whole the year round and wide geographical range from northern to southern Japan. Almost all field-collected prey animals such as cricket, ants and isopods contain them. These observatons strongly suggest that the ice nucleators transmitting from prey to predator are common in the field. Because of the ubiquity, ice nucleating active microorganism such as bacteria can be the candicates as the ice nucleator.