Circadian rhythms of locomotor activity in the Lesotho mole-rat, Cryptomys hottentotus subspecies from Sani Pass, South Africa

Schöttner, Konrad; Oosthuizen, Maria K.; Broekman, Marna; Bennett, Nigel C.

doi:10.1016/j.physbeh.2006.06.014

Cited by 22 publications

(25 citation statements)

References 29 publications

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“…Behaviorally, solitary animals display more robust locomotor activity rhythms than social species (Hart et al, 2004;Lovegrove et al, 1993Lovegrove et al, , 1995Oosthuizen et al, 2003;Riccio et al, 2000a;Schöttner et al, 2006;Vasicek et al, 2005a). These studies and the present report indicate that the gradient in responsiveness between solitary and social species is also expressed in terms of the number of individuals in a given species that express distinct rhythms of activity or light-induced Fos expression (Figure 3).…”

Section: Discussionsupporting

confidence: 73%

“…Subjected to an environment devoid of light, evolution of the visual system has led to severe regression in eye size and visual structures of the brain, with the exception of the SCN (Cooper et al, 1993a(Cooper et al, , 1993bNȇmec et al, 2007). Individuals of all mole-rat species investigated to date express lightentrainable circadian activity rhythms as well as light-induced Fos expression in the SCN (Hart et al, 2004;Oosthuizen et al, 2003Oosthuizen et al, , 2005Riccio & Goldman, 2000a;Schöttner et al, 2006;Tobler et al, 1998;Vasicek et al, 2005a;Vuillez et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

“…All species thus far investigated display locomotor activity rhythms that can be entrained to light (Hart et al, 2004;Oosthuizen et al, 2003;Riccio & Goldman, 2000a;Schöttner et al, 2006;Vasicek et al, 2005a). In addition, melatonin secretion (Gutjahr et al, 2004, Hart et al, 2004Richter et al, 2003;Vasicek et al, 2005b) and body temperature (Lovegrove & Muir, 1996;Riccio & Goldman, 2000b) also show rhythmic cycles and light can suppress melatonin secretion in the blind mole-rat (Zubidat et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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PHOTIC INDUCTION OF Fos IN THE SUPRACHIASMATIC NUCLEUS OF AFRICAN MOLE-RATS: RESPONSES TO INCREASING IRRADIANCE

Oosthuizen

Bennett

Cooper

2010

Chronobiology International

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African mole-rats (family Bathyergidae) are strictly subterranean rodent species that are rarely exposed to environmental light. Morphological and physiological adaptations to the underground environment include a severely reduced eye size and regressed visual system. Responses of the circadian system to light, however, appear to be intact, since mole-rats are able to entrain their circadian activity rhythms to the light-dark cycle and light induces Fos expression in the suprachiasmatic nucleus (SCN). Social organization varies from solitary species to highly elaborated eusocial structures, characterized by a distinct division of labor and in which one reproductive female regulates the behavior and reproductive physiology of other individuals in the colony. The authors studied light-induced Fos expression in the SCN to increasing light intensities in four mole-rat species, ranging from strictly solitary to highly social. In the solitary Cape mole-rat, light induces significant Fos expression in the SCN, and the number of Fos-immunopositive cells increases with increasing light intensity. In contrast, Fos induction in the SCN of social species was slightly greater than, but not statistically different from, the dark-control animals as is typical of most rodents. One species showed a trend for an increase in expression with increased light, whereas a second species showed no trend in expression. In the naked mole-rat, Fos expression appeared higher in the dark-controls than in the animals exposed to light, although the differences in Fos expression were not significant. These results suggest a gradient in the sensitivity of the circadian system to light in mole-rats, with a higher percentage of individuals that are unresponsive to light in correlation with the degree of sociality. In highly social species, such as the naked mole-rat that live in a relatively stable subterranean milieu in terms of food availability, temperature, constant darkness, and devoid of 24-h cyclic environmental cues, the temporal coordination of rest-wake activities may be dependent on social interactions and social status rather than on photic regulation of the circadian timing system.

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PHOTIC INDUCTION OF Fos IN THE SUPRACHIASMATIC NUCLEUS OF AFRICAN MOLE-RATS: RESPONSES TO INCREASING IRRADIANCE

Oosthuizen

Bennett

Cooper

2010

Chronobiology International

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“…These include the blind mole rat, Spalax ehrenbergi (Tobler et al 1998), the naked mole rat, Heterocephalus glaber (Riccio and Goldman 2000), the solitary Cape mole rat, Georhychus capensis, and four mole rat species of the Cryptomys genus of South Africa (Oosthuizen et al 2003; Hart et al 2004; Schöttner et al 2006). Despite the subterranean habitats, strong rhythms of activity are exhibited in all studied species (Tobler et al 1998; Riccio and Goldman 2000; Oosthuizen et al 2003; Hart et al 2004; Schöttner et al 2006) and clear rhythms in clock gene expression are seen in Spalax ehrenbergi which also possess the circadian photoreceptor melanopsin and a functional, spectrally tuned photopigment (Fig. 4c; David-Gray et al 1998, 1999; Hannibal et al 2002; Avivi et al 2002, 2004).…”

Section: A Review Of Rhythmic Physiology Research In Animals From Arrmentioning

confidence: 99%

Life in a dark biosphere: a review of circadian physiology in “arrhythmic” environments

2016

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Most of the life with which humans interact is exposed to highly rhythmic and extremely predictable changes in illumination that occur with the daily events of sunrise and sunset. However, while the influence of the sun feels omnipotent to surface dwellers such as ourselves, life on earth is dominated, in terms of biomass, by organisms isolated from the direct effects of the sun. A limited understanding of what life is like away from the sun can be inferred from our knowledge of physiology and ecology in the light biosphere, but a full understanding can only be gained by studying animals from the dark biosphere, both in the laboratory and in their natural habitats. One of the least understood aspects of life in the dark biosphere is the rhythmicity of physiology and what it means to live in an environment of low or no rhythmicity. Here we describe methods that may be used to understand rhythmic physiology in the dark and summarise some of the studies of rhythmic physiology in “arrhythmic” environments, such as the poles, deep sea and caves. We review what can be understood about the adaptive value of rhythmic physiology on the Earth’s surface from studies of animals from arrhythmic environments and what role a circadian clock may play in the dark.

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“…Mole-rats rarely venture above ground and therefore are not in frequent contact with photoperiodic cues. However, despite a regressed visual system, most mole-rat species are still able to entrain their daily activity rhythms to a circadian light cycle (Oosthuizen et al 2003;Hart et al 2004;Vasicek et al 2005;Schöttner et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Seasonal Variation in Gonadal Steroids of Males and Females in the Cape Mole-Rat (Georychus capensis): The Potential for Opportunistic Breeding

Oosthuizen

Bennett

2009

African Zoology

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Urinary testosterone concentrations in males and urinary progesterone and oestradiol concentrations in females were measured in the Cape mole-rat (Georychus capensis) and compared for the summer and winter periods. The Cape mole-rat breeds seasonally, with sexual activity and subsequent pregnancy recorded during the winter months in the southern hemisphere. Despite the fact that it has a distinct breeding season, seasonal differences in urinary hormone concentrations of both male and female Cape mole-rats were not statistically significant. This finding supports the notion the Cape mole-rat may have the opportunity to operate as an opportunistic breeder if fortuitous environmental conditions arise, such as unseasonal rainfall, occurring at these normally non-favourable times of the year.

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Circadian rhythms of locomotor activity in the Lesotho mole-rat, Cryptomys hottentotus subspecies from Sani Pass, South Africa

Cited by 22 publications

References 29 publications

PHOTIC INDUCTION OF Fos IN THE SUPRACHIASMATIC NUCLEUS OF AFRICAN MOLE-RATS: RESPONSES TO INCREASING IRRADIANCE

PHOTIC INDUCTION OF Fos IN THE SUPRACHIASMATIC NUCLEUS OF AFRICAN MOLE-RATS: RESPONSES TO INCREASING IRRADIANCE

Life in a dark biosphere: a review of circadian physiology in “arrhythmic” environments

Seasonal Variation in Gonadal Steroids of Males and Females in the Cape Mole-Rat (Georychus capensis): The Potential for Opportunistic Breeding

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