| circadian rhythms of locomotor activity in solitary and social species of african mole-rats (family: bathyergidae). | mole-rats are strictly subterranean and hardly, if ever, come into contact with external light. as a result, their classical visual system is severely regressed and the circadian system proportionally expanded. the family bathyergidae presents a unique opportunity to study the circadian system in the absence of the classical visual system in a range of species. daily patterns of activity were studied in the laboratory under constant temperature but variable lighting regimes in individually house ... | 2003 | 14667149 |
| the endogenous rhythm of plasma melatonin and its regulation by light in the highveld mole-rat (cryptomys hottentotus pretoriae): a microphthalmic, seasonally breeding rodent. | the day- and night-time levels of plasma melatonin were measured in adult male and female highveld mole-rats, cryptomys hottentotus pretoriae. this study aimed to assess whether melatonin secretion in this nocturnal, strictly subterranean but seasonally breeding rodent has a day-night rhythm and whether that rhythm is circadian and can be modified by photoperiod. in experiment 1, a day-night rhythm of plasma melatonin was found in all animals housed on a 12l:12d schedule, with significantly high ... | 2004 | 15357663 |
| characterization of gonadotrophin-releasing hormone precursor cdna in the old world mole-rat cryptomys hottentotus pretoriae: high degree of identity with the new world guinea pig sequence. | regulation of pituitary gonadotrophins by the decapeptide gonadotrophin-releasing hormone 1 (gnrh1) is crucial for the development and maintenance of reproductive functions. a common amino acid sequence for this decapeptide, designated as 'mammalian' gnrh, has been identified in all mammals thus far investigated with the exception of the guinea pig, in which there are two amino acid substitutions. among hystricognath rodents, the members of the family bathyergidae regulate reproduction in respon ... | 2005 | 15869560 |
| fos expression in the suprachiasmatic nucleus in response to light stimulation in a solitary and social species of african mole-rat (family bathyergidae). | mole-rats are strictly subterranean rodents that are rarely exposed to environmental light. they are well adapted to their environment and have reduced eyes and a severely regressed visual system. it has been shown, however, that mole-rats do exhibit endogenous circadian rhythms that can be entrained, suggesting an intact and functional circadian system. to determine whether light is the entraining agent in these animals, fos expression in response to light pulses at different circadian times wa ... | 2005 | 15878641 |
| relations between social status and the gonadotrophin-releasing hormone system in females of two cooperatively breeding species of african mole-rats, cryptomys hottentotus hottentotus and cryptomys hottentotus pretoriae: neuroanatomical and neuroendocrinological studies. | in common (cryptomys hottentotus hottentotus) and highveld (cryptomys hottentotus pretoriae) mole-rats, reproduction is subject to two forms of regulation in addition to incest avoidance. these are the only social bathyergids known to restrict breeding to a particular season; furthermore, subordinate members of their colonies show suppressed reproduction throughout the year. females from both species were assessed and compared for social and seasonal effects on the gonadotrophin-releasing hormon ... | 2006 | 16320240 |
| reproductive suppression in subordinate female highveld mole-rats (cryptomys hottentotus pretoriae): no role for endogenous opioid peptides. | the influence of endogenous opioid peptides (eops) on plasma luteinizing hormone (lh) levels in subordinate female highveld mole-rats (cryptomys hottentotus pretoriae) was investigated to elucidate the physiological mechanisms responsible for inhibiting their gonadotropin-releasing hormone (gnrh) and/or lh release. the opioid antagonist naloxone was administered either alone or with gnrh. a single injection of naloxone failed to alter plasma lh levels in dominant reproductive females or in subor ... | 2006 | 16574170 |
| hemoglobin-oxygen-affinity and acid-base properties of blood from the fossorial mole-rat, cryptomys hottentotus pretoriae. | oxygen affinity and other hematological parameters in strictly subterranean mole-rats, cryptomys hottentotus (subspecies pretoriae) were measured immediately upon capture and after 14-21 days in captivity. the ph, hematocrit, hemoglobin (hb) concentration, blood oxygen content, 2,3 bisphosphoglycerate (2,3 bpg) concentration and oxygen dissociation curves (odc), as well as tonometric measurements, were determined using whole blood. additionally odcs were also determined for stripped hemolysates ... | 2007 | 17276113 |
| heterothermy in two mole-rat species subjected to interacting thermoregulatory challenges. | maintaining a high and constant body temperature (t(b) ) is often viewed as a fundamental benefit of endothermy, but variation in t(b) is likely the norm rather than an exception among endotherms. thus, attempts to elucidate which factors cause t(b) of endotherms to deviate away from the t(b) that maximizes performance are becoming more common. one approach relies on an adaptive framework of thermoregulation, used for a long time to predict variation in t(b) of ectotherms, as a starting poin ... | 2011 | 22105982 |
| the role of host traits, season and group size on parasite burdens in a cooperative mammal. | the distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. host exposure and susceptibility may differ with sexes, reproductive effort and group size. furthermore, environmental factors may affect both the host and parasite directly and contrib ... | 2011 | 22069481 |
| orexinergic neuron numbers in three species of african mole rats with rhythmic and arrhythmic chronotypes. | in the present study, orexinergic cell bodies within the brains of rhythmic and arrhythmic circadian chronotypes from three species of african mole rat (highveld mole rat-cryptomys hottentotus pretoriae, ansell's mole rat--fukomys anselli and the damaraland mole rat--fukomys damarensis) were identified using immunohistochemistry for orexin-a. immunopositive orexinergic (orx+) cell bodies were stereologically assessed and absolute numbers of orexinergic cell bodies were determined for the distinc ... | 2011 | 22056958 |
| locomotor activity and body temperature patterns over a temperature gradient in the highveld mole-rat (cryptomys hottentotus pretoriae). | african mole-rats are strictly subterranean mammals that live in extensive burrow systems. high humidity levels in the burrows prevent mole-rats from thermoregulating using evaporative cooling. however, the relatively stable environment of the burrows promotes moderate temperatures and small daily temperature fluctuations. mole-rats therefore display a relatively wide range of thermoregulation abilities. some species cannot maintain their body temperatures at a constant level, whereas others emp ... | 2017 | 28072840 |
| adult neurogenesis and its anatomical context in the hippocampus of three mole-rat species. | african mole-rats (family bathyergidae) are small to medium sized, long-lived, and strictly subterranean rodents that became valuable animal models as a result of their longevity and diversity in social organization. the formation and integration of new hippocampal neurons in adult mammals (adult hippocampal neurogenesis, ahn) correlates negatively with age and positively with habitat complexity. here we present quantitative data on ahn in wild-derived mole-rats of 1 year and older, and briefly ... | 2014 | 24904308 |
| natural parasite infection affects the tolerance but not the response to a simulated secondary parasite infection. | parasites deplete the resources of their host and can consequently affect the investment in competing traits (e.g. reproduction and immune defence). the immunocompetence handicap hypothesis posits that testosterone (t) mediates trade-offs between parasite defence and reproductive investment by suppressing immune function in male vertebrates while more recently a role for glucocorticoids (e.g. cortisol (c)) in resource allocation has been suggested. these hypotheses however, have not always found ... | 2012 | 23300593 |