Vitrification is essential for anhydrobiosis in an African chironornid, Polypedilum vanderplanki
Vitrification is essential for anhydrobiosis in an African chironornid, Polypedilum vanderplanki
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DOI：
10.1073/pnas.0706197105
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发表时间：
2008-04-01
影响因子：
11.1
通讯作者：
Okuda, Takashi
中科院分区：
文献类型：
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作者：
Sakurai, Minoru;Furuki, Takao;Okuda, Takashi
脱水是一种极度脱水的状态，在这种状态下，生物体没有可检测到的代谢，但在再水化后仍能复活。到目前为止，已经提出了两种假设来解释细胞在脱水过程中如何受到保护：（i）相容溶质的水置换和（ii）玻璃化。本研究提供了直接的生理和物理化学证据，这些假设在非洲摇蚊，Polypedilurn vanderplanki，这是最大的多细胞动物能够脱水。差示扫描量热法测量和傅里叶变换红外（FTIR）分析表明，脱水幼虫在高达65摄氏度的温度下处于玻璃态。通过加热或允许轻微的水分吸收从玻璃态到橡胶态的变化大大降低了脱水幼虫的存活率。此外，FTIR光谱表明，糖形成的氢键与磷脂和膜保持在液晶状态的脱水幼虫。这些结果表明，幼虫的A vanderplanki生存极端脱水取代正常的细胞内介质与生物玻璃。傅立叶变换红外光谱显微图谱显示，进入脱水生活状态后，范氏藻积累了非还原性二糖海藻糖，并均匀分布在整个脱水体中。因此，我们认为海藻糖在水置换和细胞内玻璃形成中起着重要作用，尽管其他化合物肯定参与了这些现象。
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, Polypedilurn 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 degrees 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 A vanderplanki survive extreme dehydration by replacing the normal intracellular medium with a biological glass. When entering anhydrobiosis, A 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.