Kerryn L Grenfell, Paul J Jacobs, Nigel C Bennett, Daniel W Hart
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引用次数: 0
摘要
光被认为是哺乳动物生物节律(包括运动活动)的主要诱导因素。然而,哺乳动物会经历不同的环境和光照条件,其中包括那些主要没有光照刺激的环境,如地下环境。在这项研究中,我们以昼夜节律(LA)为代表,调查了在没有光刺激的生活环境中,哪种环境线索(光或环境温度(Ta))对哺乳动物的昼夜节律具有最强的调节作用。为了解决这个问题,本研究将一种非洲地下鼹鼠--达玛兰鼹鼠(Fukomys damarensis)暴露于六种不同组合的光照和Ta周期中。与之前的文献相反,当提供可靠的光提示时,达玛兰鼹鼠在恒定的Ta下表现出夜间、昼夜或心律不齐的LA模式。在模拟洞穴环境的恒定黑暗和 24 小时 Ta 循环条件下,所有鼹鼠都在最冷的 12 小时内最为活跃。这一发现表明,在没有可靠光照提示的地下环境中,达玛拉尔鼹鼠在挖掘活动中经历的有限散热和能量限制使Ta成为一个可靠而稳定的 "计时 "变量。此外,当在 24 小时 Ta 周期下为达玛兰鼹鼠提供可靠的光提示(12 亮:12 暗)时,本研究首次提出了 Ta 周期比光照和黑暗周期更强烈地影响地下哺乳动物 LA 节律的证据。同样,达玛兰鼹鼠在最凉爽的 12 小时内更为活跃,而不管这段时间是在光照阶段还是在黑暗阶段。然而,这项研究并没有将 "Ta "节律与 "掩蔽 "节律明确区分开来,因此,我们建议在今后的研究中继续这样做。
The role of ambient temperature and light as cues in the control of circadian rhythms of Damaraland mole-rat.
Light is considered the primary entrainer for mammalian biological rhythms, including locomotor activity (LA). However, mammals experience different environmental and light conditions, which include those predominantly devoid of light stimuli, such as those experienced in subterranean environments. In this study, we investigated what environmental cue (light or ambient temperature (Ta)) is the strongest modulator of circadian rhythms, by using LA as a proxy, in mammals that experience a lifestyle devoid of light stimuli. To address this question, this study exposed a subterranean African mole-rat species, the Damaraland mole-rat (Fukomys damarensis), to six light and Ta cycles in different combinations. Contrary to previous literature, when provided with a reliable light cue, Damaraland mole rats exhibited nocturnal, diurnal, or arrhythmic LA patterns under constant Ta. While under constant darkness and a 24-hour Ta cycle mimicking the burrow environment, all mole-rats were most active during the coolest 12-hour period. This finding suggests that in a subterranean environment, which receives no reliable photic cue, the limited heat dissipation and energy constraints during digging activity experienced by Damaraland mole-rats make Ta a reliable and consistent "time-keeping" variable. More so, when providing a reliable light cue (12 light: 12 dark) to Damaraland mole-rats under a 24-hour Ta cycle, this study presents the first evidence that cycles of Ta affect the LA rhythm of a subterranean mammal more strongly than cycles of light and darkness. Once again, Damaraland mole-rats were more active during the coolest 12-hour period regardless of whether this fell during the light or dark phase. However, conclusive differentiation of entrainment to Ta from that of masking was not achieved in this study, and as such, we have recommended future research avenues to do so.
期刊介绍:
Chronobiology International is the journal of biological and medical rhythm research. It is a transdisciplinary journal focusing on biological rhythm phenomena of all life forms. The journal publishes groundbreaking articles plus authoritative review papers, short communications of work in progress, case studies, and letters to the editor, for example, on genetic and molecular mechanisms of insect, animal and human biological timekeeping, including melatonin and pineal gland rhythms. It also publishes applied topics, for example, shiftwork, chronotypes, and associated personality traits; chronobiology and chronotherapy of sleep, cardiovascular, pulmonary, psychiatric, and other medical conditions. Articles in the journal pertain to basic and applied chronobiology, and to methods, statistics, and instrumentation for biological rhythm study.
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