Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada.
Proc Natl Acad Sci U S A. 2012 Aug 28;109(35):14247-52. doi: 10.1073/pnas.1205012109. Epub 2012 Aug 13.
Global warming is intensifying interest in the mechanisms enabling ectothermic animals to adjust physiological performance and cope with temperature change. Here we show that embryonic temperature can have dramatic and persistent effects on thermal acclimation capacity at multiple levels of biological organization. Zebrafish embryos were incubated until hatching at control temperature (T(E) = 27 °C) or near the extremes for normal development (T(E) = 22 °C or 32 °C) and were then raised to adulthood under common conditions at 27 °C. Short-term temperature challenge affected aerobic exercise performance (U(crit)), but each T(E) group had reduced thermal sensitivity at its respective T(E). In contrast, unexpected differences arose after long-term acclimation to 16 °C, when performance in the cold was ∼20% higher in both 32 °C and 22 °C T(E) groups compared with 27 °C T(E) controls. Differences in performance after acclimation to cold or warm (34 °C) temperatures were partially explained by variation in fiber type composition in the swimming muscle. Cold acclimation changed the abundance of 3,452 of 19,712 unique and unambiguously identified transcripts detected in the fast muscle using RNA-Seq. Principal components analysis differentiated the general transcriptional responses to cold of the 27 °C and 32 °C T(E) groups. Differences in expression were observed for individual genes involved in energy metabolism, angiogenesis, cell stress, muscle contraction and remodeling, and apoptosis. Therefore, thermal acclimation capacity is not fixed and can be modified by temperature during early development. Developmental plasticity may thus help some ectothermic organisms cope with the more variable temperatures that are expected under future climate-change scenarios.
全球变暖加剧了人们对变温动物调节生理机能和应对温度变化机制的兴趣。本研究表明，胚胎温度对生物组织多层次的热适应能力具有显著而持久的影响。研究人员将斑马鱼胚胎在对照温度（T(E) = 27 °C）或接近正常发育极限温度（T(E) = 22 °C 或 32 °C）下孵化，然后在 27 °C 下的常见条件下饲养至成年。短期温度挑战会影响有氧运动性能（U(crit)），但每个 T(E)组在各自的 T(E)下的热敏感性降低。相比之下，在长期适应 16 °C 后出现了意想不到的差异，当在冷水中进行测试时，32 °C 和 22 °C T(E)组的性能比 27 °C T(E)对照组高约 20%。适应冷或暖（34 °C）温度后的性能差异部分可通过游泳肌中纤维类型组成的变化来解释。冷适应改变了在快速肌肉中使用 RNA-Seq 检测到的 19712 个独特和明确鉴定的转录本中的 3452 个转录本的丰度。主成分分析区分了 27 °C 和 32 °C T(E)组对冷的一般转录反应。观察到个别基因在能量代谢、血管生成、细胞应激、肌肉收缩和重塑以及细胞凋亡中表达的差异。因此，热适应能力不是固定的，可以通过早期发育过程中的温度进行修改。发育可塑性可能有助于一些变温动物应对未来气候变化情景下预期会更加多变的温度。
