Rest-activity rhythm of the blind mole rat Spalax ehrenbergi under different lighting conditions

Tobler, Irene; Herrmann, Miriam; Cooper, Howard M.; Negroni, Julia; Nevo, Eviatar; Achermann, Peter

doi:10.1016/s0166-4328(98)00012-6

Cited by 42 publications

(27 citation statements)

References 30 publications

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“…One of the most remarkable adaptations is the ability of this species to discriminate between light and dark ambient lighting and to entrain the internal circadian clock accordingly (Negroni et al, 1997;Tobler et al, 1998). Clearly, the photoperiodic responses of S.…”

Section: Discussionmentioning

confidence: 99%

“…Rhythmicity in biological functions has been described in several rodent species, including social voles, Microtus socialis (Haim et al, 2005; and the 'blind' mole rats, Spalax ehrenbergi (Ben-Shlomo et al, 1996b;Tobler et al, 1998). The cycles of day and night and the annual pattern of changing day lengths generate a reliable photosignal for temporal coordination of a wide array of circadian and seasonal functions, respectively, in mammals living outside the tropics (Goldman, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Photosensitivity to different light intensities in blind and sighted rodents

Zubidat

Nelson

Haim

2009

Journal of Experimental Biology

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SUMMARYPhotoperiod is an important cue regulating biological rhythms in mammals, including 'blind' subterranean and sighted fossorial rodent species. These species may respond differentially to changes in light quality according to their retinal complexity. The effects of increasing light intensity on daily rhythms of urine excretion and urinary output of 6-sulfatoxymelatonin levels were compared in 'blind' mole rats Spalax ehrenbergi and sighted social voles, Microtus socialis. Our results show that the threshold irradiance required to entrain rhythms of voles is three magnitudes greater than that for mole rats. The results suggest that mole rats have an operational photoreceptive pathway with a lower threshold irradiance than voles. Such a low threshold reflects the remarkable capability of this 'blind' species to utilize light signals even under challenging light conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photosensitivity to different light intensities in blind and sighted rodents

Zubidat

Nelson

Haim

2009

Journal of Experimental Biology

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“…behavioral studies in Spalax (11) and link the activity pattern of these species with the cellular cycling in sighted animals. The poor sPer3 oscillation and the absence of light influence on sPer3 expression levels may suggest a role for sPer3 outside the central pacemaker.…”

Section: Discussion Adaptive Selection On Per Genes In Spalax To Lifementioning

confidence: 99%

“…Spalax lives in total darkness, yet, it perceives the daily and seasonal temporal cycles underground (9). Behaviorally, Spalax displays polyphasic and polytypic day-night activity patterns (10,11) coupled with polymorphic (12) and seasonal ʈ variation, supported by a unique photoperiodic perception mechanism (9). Spalax has a degenerated s.c. functional eye (13,14), which, together with the harderian gland, participates in photoperiodic perception (9,(15)(16)(17)(18).…”

Section: The Evolutionary Model Of Blind Subterranean Mammalsmentioning

confidence: 99%

Circadian genes in a blind subterranean mammal II: Conservation and uniqueness of the threePeriodhomologs in the blind subterranean mole rat,Spalax ehrenbergisuperspecies

Avivi

Oster

Joel

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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We demonstrated that a subterranean, visually blind mammal has a functional set of three Per genes that are important components of the circadian clockwork in mammals. The mole rat superspecies Spalax ehrenbergi is a blind subterranean animal that lives its entire life underground in darkness. It has degenerated eyes, but the retina and highly hypertrophic harderian gland are involved in photoperiodic perception. All three Per genes oscillate with a periodicity of 24 h in the suprachiasmatic nuclei, eye, and harderian gland and are expressed in peripheral organs. This oscillation is maintained under constant conditions. The light inducibility of sPer1 and sPer2, which are similar in structure to those of other mammals, indicates the role of these genes in clock resetting. However, sPer3 is unique in mammals and has two truncated isoforms, and its expressional analysis leaves its function unresolved. Per's expression analysis in the harderian gland suggests an important participation of this organ in the stabilization and resetting mechanism of the central pacemaker in the suprachiasmatic nuclei and in unique adaptation to life underground. L ife on Earth is adapted to cyclical phenomena imposed by the external environment (1). Most organisms have circadian systems that synchronize physiological events to the external 24-h cycle (2). The underlying molecular-genetic mechanisms of these clocks exhibit an extraordinary evolutionary conservation from cyanobacteria through plants, fruit flies, and mammals. All of these clock systems consist of autoregulatory transcriptional͞ translational feedback loops with positive͞negative regulatory elements and similar genetic machinery (3, 4).Two basic helix-loop-helix PAS (PER-ARNT-SIM) transcription factors, CLOCK and MOP3 (BMAL1), form the positive elements of the system and drive transcription of three Period (Per 1, 2, 3) and two Cryptochrome (Cry 1, 2) genes. The protein products of these genes are thought to be components of a negative feedback complex that inhibits the CLOCK͞MOP3 heterodimer, thereby closing the circadian loop.The enigma of circadian rhythms in a blind subterranean mammal is intriguing (5-7). We have already shown that a CLOCK͞MOP3-driven clock exists in Spalax (8). Here we continue to decipher its circadian machinery. The Evolutionary Model of Blind Subterranean MammalsThe blind subterranean mammals, mole rats of the Spalax ehrenbergi superspecies in Israel, consist of four species that have been studied multidisciplinarily as an evolutionary model of speciation and adaptation (5-7). Spalax lives in total darkness, yet, it perceives the daily and seasonal temporal cycles underground (9). Behaviorally, Spalax displays polyphasic and polytypic day-night activity patterns (10, 11) coupled with polymorphic (12) and seasonal ʈ variation, supported by a unique photoperiodic perception mechanism (9). Spalax has a degenerated s.c. functional eye (13,14), which, together with the harderian gland, participates in photoperiodic perception (9, 15-18). The retina h...

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“…Expression of circadian genes in blind Spalax may highlight the genetic basis of its behavioral pattern of circadian rhythmicity (19)(20)(21)(22). We have already cloned the Spalax cDNA homologs of Per1, Per2, Per3, Tim, Cry1, and Cry2 (unpublished results).…”

Section: Discussionmentioning

confidence: 99%

Biological clock in total darkness: TheClock/MOP3circadian system of the blind subterranean mole rat

Avivi

Albrecht

Oster

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

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Blind subterranean mole rats retain a degenerated, subcutaneous, visually blind but functionally circadian eye involved in photoperiodic perception. Here we describe the cloning, sequence, and expression of the circadian Clock and MOP3 cDNAs of the Spalax ehrenbergi superspecies in Israel. Both genes are relatively conserved, although characterized by a significant number of amino acid substitutions. The glutamine-rich area of Clock, which is assumed to function in circadian rhythmicity, is expanded in Spalax compared with that of humans and mice, and is different in amino acid composition from that of rats. We also show that MOP3 is a bona fide partner of Spalax Clock and that the Spalax Clock͞MOP3 dimer is less potent than its human counterpart in driving transcription. We suggest that this reduction in transcriptional activity may be attributed to the Spalax Clock glutamine-rich domain, which is unique in its amino acid composition compared with other studied mammalian species. Understanding Clock͞MOP3 function could highlight circadian mechanisms in blind mammals and their unique pattern as a result of adapting to life underground.

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Rest-activity rhythm of the blind mole rat Spalax ehrenbergi under different lighting conditions

Cited by 42 publications

References 30 publications

Photosensitivity to different light intensities in blind and sighted rodents

Photosensitivity to different light intensities in blind and sighted rodents

Circadian genes in a blind subterranean mammal II: Conservation and uniqueness of the threePeriodhomologs in the blind subterranean mole rat,Spalax ehrenbergisuperspecies

Biological clock in total darkness: TheClock/MOP3circadian system of the blind subterranean mole rat

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