Mussel acclimatization to high, variable temperatures is lost slowly upon transfer to benign conditions
Mussel acclimatization to high, variable temperatures is lost slowly upon transfer to benign conditions
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DOI：
10.1242/jeb.222893
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发表时间：
2020-01
影响因子：
2.8
通讯作者：
N. Moyen;G. Somero;Mark W. Denny-
中科院分区：
文献类型：
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作者：
N. Moyen;G. Somero;Mark W. Denny-
摘要 气候变化正在增加动物面临的温度变化，而热适应使动物能够适应这种变化。尽管已经对热适应率进行了一些研究，但对于在不持续暴露于热应激的情况下这些适应性变化能持续多久仍知之甚少。这项研究探讨了在持续浸没期间温度变化最小化时野外适应状态丧失的速度。从高区和低区（日温度范围分别为~12°C 和~5°C）收集具有不同适应状态的加州贻贝（Mytilus californianus），然后在 15°C 下浸泡 8 周。每周，都会测量贻贝的心脏热性能作为适应状态的指标：记录临界温度（Tcrit）和平线温度（Tflat）。经过 8 周的持续浸没，高区贻贝的平均 Tcrit 较基线下降了 1.07°C，但低区贻贝的平均 Tcrit 没有变化。高区和低区贻贝的平均最大心率 (HR) 和静息 HR 分别下降约 12% 和 35%。两组中的 Tflat 均未变化。这些数据表明，与 Tflat 相比，Tcrit 和 HR 在响应动物每日温度范围缩小时更具生理可塑性，并且动物之前的适应状态（高与低）影响 Tcrit 的适应能力。高区贻贝的心脏热性能大约需要两个月的时间才能达到低区贻贝的水平，这表明对高温和多变温度的适应可能会持续足够长的时间，以使这些动物能够应对间歇性的热应激。摘要：随着持续的浸没，对高温、多变温度的适应能力会慢慢丧失，这可能有助于动物在间歇性应激热事件中生存。先前的适应状态会影响持续浸没时观察到的变化。
ABSTRACT Climate change is increasing the temperature variability animals face, and thermal acclimatization allows animals to adjust adaptively to this variability. Although the rate of heat acclimatization has received some study, little is known about how long these adaptive changes remain without continuing exposure to heat stress. This study explored the rate at which field acclimatization states are lost when temperature variability is minimized during constant submersion. California mussels (Mytilus californianus) with different acclimatization states were collected from high- and low-zone sites (∼12 versus ∼5°C daily temperature ranges, respectively) and then kept submerged at 15°C for 8 weeks. Each week, the cardiac thermal performance of mussels was measured as a metric of acclimatization state: critical (Tcrit) and flatline (Tflat) temperatures were recorded. Over 8 weeks of constant submersion, the mean Tcrit of high-zone mussels decreased by 1.07°C from baseline, but low-zone mussels' mean Tcrit was unchanged. High- and low-zone mussels' mean maximum heart rate (HR) and resting HR decreased ∼12 and 35%, respectively. Tflat was unchanged in both groups. These data suggest that Tcrit and HR are more physiologically plastic in response to the narrowing of an animal's daily temperature range than Tflat is, and that an animal's prior acclimatization state (high versus low) influences the acclimatory capacity of Tcrit. Approximately 2 months were required for the cardiac thermal performance of the high-zone mussels to reach that of the low-zone mussels, suggesting that acclimatization to high and variable temperatures may persist long enough to enable these animals to cope with intermittent bouts of heat stress. Summary: Acclimatization to high, variable temperatures is lost slowly with constant submersion, potentially facilitating animals’ survival during intermittent stressful thermal events. Previous acclimatization state influences the changes observed with constant submersion.