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Chris G Faulkes - One of the best experts on this subject based on the ideXlab platform.
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DNA methylation clocks as a predictor for ageing and age estimation in naked mole-rats, Heterocephalus glaber.
'Impact Journals LLC', 2020Co-Authors: Lowe R, Af Danson, Vk Rakyan, Yildizoglu S, Saldmann F, Viltard M, Friedlander G, Chris G FaulkesAbstract:The naked mole-rat, Heterocephalus glaber (NMR), the longest-lived rodent, is of significance and interest in the study of biomarkers for ageing. Recent breakthroughs in this field have revealed 'epigenetic clocks' that are based on the temporal accumulation of DNA methylation at specific genomic sites. Here, we validate the hypothesis of an epigenetic clock in NMRs based on changes in methylation of targeted CpG sites. We initially analysed 51 CpGs in NMR livers spanning an age range of 39-1,144 weeks and found 23 to be significantly associated with age (p
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eruption rates of the mandibular incisors of naked mole rats Heterocephalus glaber
Journal of Zoology, 2006Co-Authors: B K B Berkovitz, Chris G FaulkesAbstract:Naked mole-rats Heterocephalus glaber are highly social hystricomorph rodents endemic to the arid regions of East Africa. Living entirely underground, they excavate an extensive system of tunnels with their continuously growing extra-buccal incisors. The majority of the burrow is composed of foraging tunnels, constructed in search of the underground roots and tubers that form their staple diet. Subterranean foraging imposes risks associated with not finding food, and a high energetic cost, and in addition could be limited by the rate of wear of the incisor teeth. The aim of this study was to determine eruption rates for mandibular incisors in naked mole-rats to investigate whether they showed evidence of faster eruption as an adaptation to their subterranean niche and mode of digging. Impeded eruption rates (when the teeth were left in normal occlusion) were initially determined over a period of 1 week in a group of 12 naked mole-rats kept in laboratory conditions. Unimpeded eruption rates were then monitored in the same animals by cutting one mandibular incisor free of occlusion thrice weekly, and measuring growth over a 2-week period. Mean daily impeded eruption rates were c. 228.7±17.5 μm, while mean daily unimpeded rates were higher at c. 624.7±10.4 μm. While impeded eruption rates under laboratory conditions may be an underestimate of the rates occurring in the wild, unimpeded rates (usually about twice the impeded rate) indicate the maximum potential eruption rates of the teeth and are independent of functional activity. These data are not dissimilar from those determined for laboratory rodents and lagomorphs suggesting that the naked mole-rat does not display unusual patterns of eruptive behaviour. Tooth wear resulting from their subterranean lifestyle may be offset as a limiting factor by the social behaviour of the naked mole-rat, where digging activity is distributed among a large workforce during favourable burrowing conditions.
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phylogeographical patterns of genetic divergence and speciation in african mole rats family bathyergidae
Molecular Ecology, 2004Co-Authors: Chris G Faulkes, Erik Verheyen, W VerheyenAbstract:African mole-rats are subterranean Hystricomorph rodents, distributed widely throughout sub-Saharan Africa, and displaying a range of social and reproductive strategies from solitary dwelling to the ‘insect-like’ sociality of the naked mole-rat, Heterocephalus glaber . Both molecular systematic studies of Rodentia and the fossil record of bathyergids indicate an ancient origin for the family. This study uses an extensive molecular phylogeny and mitochondrial cytochrome b and 12s rRNA molecular clocks to examine in detail the divergence times, and patterns of speciation of the five extant genera in the context of rift valley formation in Africa. Based on a value of 40–48 million years ago (Myr) for the basal divergence of the family ( Heterocephalus ), we estimate divergence times of 32–40 Myr for Heliophobius , 20–26 Myr for Georychus / Bathyergus and 12–17 Myr for Cryptomys , the most speciose genus. While early divergences may have been independent of rifting, patterns of distribution of later lineages may have been influenced directly by physical barriers imposed by the formation of the Kenya and Western Rift, and indirectly by accompanying climatic and vegetative changes. Rates of chromosomal evolution and speciation appear to vary markedly within the family. In particular, the genus Cryptomys appears to have undergone an extensive radiation and shows the widest geographical distribution. Of the two distinct clades within this genus, one exhibits considerable karyotypic variation while the other does not, despite comparatively high levels of sequence divergence between some taxa. These different patterns of speciation observed both within the family and within the genus Cryptomys may have been a result of environmental changes associated with rifting.
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intracolony aggression in the eusocial naked mole rat Heterocephalus glaber
Animal Behaviour, 2001Co-Authors: F M Clarke, Chris G FaulkesAbstract:Abstract In colonies of the eusocial naked mole-rat, breeding is monopolized by one dominant female (the ‘queen’) and one to three males. Aggression in the form of shoving (prolonged pushes involving nose to nose contact) is frequently observed in captive colonies and is principally initiated by breeders. It has been suggested that shoving by queens functions primarily to suppress reproduction in subordinates (threat reduction hypothesis) or to incite work activity in nonbreeding ‘helpers’ (work conflict hypothesis). We tested predictions of both hypotheses by examining shoving in five captive colonies before and after removing breeders. Shoving was strongly associated with reproductive status. The vast majority of shoves were carried out by the queen, and to a lesser extent breeding males, and the onset of reproductive activity coincided with the onset, or greatly increased rates, of shoving. No evidence for the work conflict hypothesis was found. Queens shoved high-ranking and large colony members most, a finding that does not allow discrimination between hypotheses. Those males that posed the greatest threat to the queen's reproductive dominance, namely future breeding males, were shoved most, providing some support for the threat reduction hypothesis. However, evidence that queens targeted those females that posed the greatest threat, females that were to succeed them, was equivocal. Queen shoving may have several functions, depending on social context, in inhibiting reproduction in subordinates of both sexes, maintaining social order, and in inciting work-related behaviours in colony members, all of which ultimately increase the reproductive success of queens.
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Microsatellite primers for the African mole-rat genus Cryptomys and cross-species amplification within the family Bathyergidae
Molecular Ecology Notes, 2001Co-Authors: Tamsin M. Burland, Jacqueline M. Bishop, Colleen O'ryan, Chris G FaulkesAbstract:We report 11 microsatellite loci for the African mole-rat genus Cryptomys (Rodentia: Bathyergidae), isolated from the Damaraland mole-rat (Cryptomys damarensis) and the Common mole-rat (C. hottentotus hottentotus). All loci are highly polymorphic in the source species, with between six and 13 alleles and observed heterozygosity ranging from 0.54 to 0.86. Two C. damarensis loci (DMR1 and 6) may be located on the X-chromosome. Cross-species amplification was investigated in 10 Bathyergid species, representative of the five genera. The majority of loci amplified polymorphic product in all Cryptomys species tested. Amplification was also widespread in the other genera, except in Heterocephalus.
Rochelle Buffenstein - One of the best experts on this subject based on the ideXlab platform.
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Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age
eLife, 2018Co-Authors: J. Graham Ruby, Megan Smith, Rochelle BuffensteinAbstract:The longest-lived rodent, the naked mole-rat (Heterocephalus glaber), has a reported maximum lifespan of >30 years and exhibits delayed and/or attenuated age-associated physiological declines. We questioned whether these mouse-sized, eusocial rodents conform to Gompertzian mortality laws by experiencing an exponentially increasing risk of death as they get older. We compiled and analyzed a large compendium of historical naked mole-rat lifespan data with >3000 data points. Kaplan-Meier analyses revealed a substantial portion of the population to have survived at 30 years of age. Moreover, unlike all other mammals studied to date, and regardless of sex or breeding-status, the age-specific hazard of mortality did not increase with age, even at ages 25-fold past their time to reproductive maturity. This absence of hazard increase with age, in defiance of Gompertz's law, uniquely identifies the naked mole-rat as a non-aging mammal, confirming its status as an exceptional model for biogerontology.
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fibroblasts from naked mole rats are resistant to multiple forms of cell injury but sensitive to peroxide ultraviolet light and endoplasmic reticulum stress
Journals of Gerontology Series A-biological Sciences and Medical Sciences, 2008Co-Authors: Adam B Salmon, Rochelle Buffenstein, Amir Sadighi A Akha, Richard A MillerAbstract:Fibroblasts from long-lived mutant mice are resistant to many forms of lethal injury as well as to the metabolic effects of rotenone and low-glucose media. Here we evaluated fibroblasts from young adult naked mole-rats (NMR; Heterocephalus glaber), a rodent species in which maximal longevity exceeds 28 years. Compared to mouse cells NMR cells were resistant to cadmium, MMS, paraquat, heat, and low glucose media, consistent with the idea that cellular resistance to stress may contribute to disease resistance and longevity. Surprisingly, NMR cells were more sensitive than mouse cells to H2O2, UV light, and rotenone. NMR cells, like cells from Snell dwarf mice, were more sensitive to tunicamycin and thapsigargin, which interfere with the function of the endoplasmic reticulum (ER stress). The sensitivity of both Snell dwarf and NMR cells to ER stress suggests that alterations in the unfolded protein response might modulate cell survival and aging rate.
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Vascular aging in the longest-living rodent, the naked mole rat.
American journal of physiology. Heart and circulatory physiology, 2007Co-Authors: Anna Csiszar, Rochelle Buffenstein, Nazar Labinskyy, Zsuzsanna Orosz, Zhao Xiangmin, Zoltan UngvariAbstract:The naked mole rat (NMR; Heterocephalus glaber) is the longest-living rodent known [maximum lifespan potential (MLSP): >28 yr] and is a unique model of successful aging showing attenuated declines ...
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A stereotaxic atlas of the brain of the naked mole-rat (Heterocephalus glaber)
Neuroscience, 2006Co-Authors: J. Xiao, Jonathan B. Levitt, Rochelle BuffensteinAbstract:The naked mole-rat (Rodentia, Bathyergidae: Heterocephalus glaber) is a strictly subterranean eusocial mammal. These rodents show a suite of morphological and physiological adaptations, including brain specializations, to this underground milieu that they have inhabited since the early Miocene. Recently, naked mole-rats have received considerable attention as the longest living rodent known, and some of these brain specializations may be potentially important to their exceptional longevity. To serve as a basis for future brain studies, we have constructed a stereotaxic atlas of the brain of this species, labeling all major brain structures.
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The Naked Mole Rat--A New Record for the Oldest Living Rodent
Science of aging knowledge environment : SAGE KE, 2002Co-Authors: Rochelle Buffenstein, Jennifer U M JarvisAbstract:We report a new record for the world's longest-lived rodent, a male naked mole rat (Heterocephalus glaber). On the basis of his weight at capture, this animal was approximately 1 year old when collected near Mtito Andei, Kenya in July/August 1974. He died in April 2002, indicating that he lived for more than 28 years. As such, his life-span surpassed the previous longevity record for a rodent, which was held by a porcupine (Hystrix brachyura) that lived for 27 years and 4 months.
Thomas J Park - One of the best experts on this subject based on the ideXlab platform.
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fructose driven glycolysis supports anoxia resistance in the naked mole rat
Science, 2017Co-Authors: Thomas J Park, Jane Reznick, Bethany L Peterson, Damir Omerbasic, Henning P J L Kuich, Christin Zasada, Brigitte M Browe, Gregory R C Blass, Wiebke HamannAbstract:The African naked mole-rat’s (Heterocephalus glaber) social and subterranean lifestyle generates a hypoxic niche. Under experimental conditions, naked mole-rats tolerate hours of extreme hypoxia and survive 18 minutes of total oxygen deprivation (anoxia) without apparent injury. During anoxia, the naked mole-rat switches to anaerobic metabolism fueled by fructose, which is actively accumulated and metabolized to lactate in the brain. Global expression of the GLUT5 fructose transporter and high levels of ketohexokinase were identified as molecular signatures of fructose metabolism. Fructose-driven glycolytic respiration in naked mole-rat tissues avoids feedback inhibition of glycolysis via phosphofructokinase, supporting viability. The metabolic rewiring of glycolysis can circumvent the normally lethal effects of oxygen deprivation, a mechanism that could be harnessed to minimize hypoxic damage in human disease.
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selective inflammatory pain insensitivity in the african naked mole rat Heterocephalus glaber
PLOS Biology, 2008Co-Authors: Thomas J Park, Ewan St John Smith, Ying Lu, Rene Juttner, Jing Hu, Antje Brand, Christiane Wetzel, Nevena Milenkovic, Bettina Erdmann, Paul A HeppenstallAbstract:In all mammals, tissue inflammation leads to pain and behavioral sensitization to thermal and mechanical stimuli called hyperalgesia. We studied pain mechanisms in the African naked mole-rat, an unusual rodent species that lacks pain-related neuropeptides (e.g., substance P) in cutaneous sensory fibers. Naked mole-rats show a unique and remarkable lack of pain-related behaviors to two potent algogens, acid and capsaicin. Furthermore, when exposed to inflammatory insults or known mediators, naked mole-rats do not display thermal hyperalgesia. In contrast, naked mole-rats do display nocifensive behaviors in the formalin test and show mechanical hyperalgesia after inflammation. Using electrophysiology, we showed that primary afferent nociceptors in naked mole-rats are insensitive to acid stimuli, consistent with the animal's lack of acid-induced behavior. Acid transduction by sensory neurons is observed in birds, amphibians, and fish, which suggests that this tranduction mechanism has been selectively disabled in the naked mole-rat in the course of its evolution. In contrast, nociceptors do respond vigorously to capsaicin, and we also show that sensory neurons express a transient receptor potential vanilloid channel-1 ion channel that is capsaicin sensitive. Nevertheless, the activation of capsaicin-sensitive sensory neurons in naked mole-rats does not produce pain-related behavior. We show that capsaicin-sensitive nociceptors in the naked mole-rat are functionally connected to superficial dorsal horn neurons as in mice. However, the same nociceptors are also functionally connected to deep dorsal horn neurons, a connectivity that is rare in mice. The pain biology of the naked mole-rat is unique among mammals, thus the study of pain mechanisms in this unusual species can provide major insights into what constitutes “normal” mammalian nociception.
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growth deficient vomeronasal organs in the naked mole rat Heterocephalus glaber
Brain Research, 2007Co-Authors: Timothy D Smith, Kunwar P Bhatnagar, John C Dennis, Edward E Morrison, Thomas J ParkAbstract:The naked mole-rat (Heterocephalus glaber) is unusual in numerous life history characteristics as well as its eusocial organization. This species demonstrates widespread sexual suppression and prominent scent marking, behaviors that have been associated with pheromonal communication involving the vomeronasal organ in other rodents. Yet, previous studies indicate that urinary signals do not mediate sexual suppression in Heterocephalus. Surprisingly, no previous studies have examined the vomeronasal organ in this species. Here, we show that Heterocephalus is unique among rodents in showing no evidence of postnatal volumetric growth in the vomeronasal neuroepithelium. Subadults from birth to weaning fell within the same volume range as adults regardless of breeding/non-breeding status of the latter. A comparison of existing ontogenetic data on other mammals suggests that the proportionally small VNOs of Heterocephalus may be explained by a deficiency in VNNE growth. Growth deficiency of the vomeronasal organ in Heterocephalus may relate to a diminished role that pheromones play in certain social interactions for this species, such as breeding suppression. In light of the unique aspects of the vomeronasal organ in Heterocephalus, comparative studies of rodents may provide a model for understanding variation of this sensory system in other mammalian orders including primates, an order which shows a range from vestigial to demonstrably functional vomeronasal organs.
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Features of visual function in the naked mole-rat Heterocephalus glaber
Journal of Comparative Physiology A, 2005Co-Authors: John R. Hetling, Monica S. Baig-silva, Christopher M. Comer, Machelle T. Pardue, Dalia Y. Samaan, Nasser M. Qtaishat, David R. Pepperberg, Thomas J ParkAbstract:The eyes and visual capacity of the naked mole-rat, Heterocephalus glaber , a subterranean rodent, were evaluated using anatomical, biochemical, and functional assays, and compared to other rodents of similar body size (mouse and gerbil). The eye is small compared to mouse, yet possesses cornea, lens, and retina with typical mammalian organization. The optic nerve cross-sectional area and fiber density are ~10% and ~50% that of gerbil, respectively. Levels per unit retinal area of 11- cis and all- trans retinal, derivatives of vitamin A associated with the visual cycle, are comparable to mouse. The corneal electroretinogram (ERG) exhibits early and late negative components that scale with flash strength; raising the body temperature of this poikilothermic animal from 30°C (normal for H. glaber ) to 37°C (normal for mouse) revealed an ERG response with typically mammalian features, but greatly attenuated and with slower kinetics. Leaving the nest chamber was a behavior correlated with light onset displayed preferentially by breeding females. Optical models of five mole-rat eyes suggest reasonable, but variable, image formation at the retina, possibly related to age. Results are consistent with amorphous light detection, possibly useful for circadian entrainment or escape behavior in the event of tunnel breeches.
Melissa M Holmes - One of the best experts on this subject based on the ideXlab platform.
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aggression and motivation to disperse in eusocial naked mole rats Heterocephalus glaber
Animal Behaviour, 2020Co-Authors: Ilapreet Toor, Phoebe D Edwards, Nagham Kaka, Rebecca Whitney, Justine Ziolkowski, Ashley D Monks, Melissa M HolmesAbstract:Naked mole-rats are eusocial mammals that live in hierarchies consisting of one breeding female, one to three male consorts and their reproductively suppressed offspring. A ‘disperser morph’ subcaste has been suggested with a subset of nonbreeders exhibiting motivation to leave their natal colony and mate with unfamiliar conspecifics. To test the hypotheses that intrinsic colony variables (e.g. population density, sex ratio, queen temperament) influence the dispersal phenotype, and that males and females differ in responsiveness to these variables, we evaluated dispersal behaviour in 17 laboratory colonies. Queen aggression was associated with the number of female, but not male, dispersers, although dispersers were not themselves targets of queen aggression. Female dispersers were more aggressive than their nondispersing sisters, although still less aggressive than queens overall. Following outpairing with an unfamiliar opposite-sex animal, dispersers and nondispersers produced litters at similar rates, demonstrating that motivation to leave the colony, and not anticipatory reproductive maturation, is the key to successful dispersal. Collectively, these data suggest that aggressive naked mole-rat queens motivate dispersal in their daughters and that female dispersers show traits consistent with successful queens (e.g. aggression).
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olfaction and social cognition in eusocial naked mole rats Heterocephalus glaber
Animal Behaviour, 2015Co-Authors: Ilapreet Toor, David Clement, Erika N Carlson, Melissa M HolmesAbstract:Olfaction is the primary sensory modality involved in social cognition among rodents. Eusocial naked mole-rats live in large subterranean colonies with different castes and subcastes of individuals showing unique behavioural profiles. Thus, these animals are constantly faced with social decisions, which are key to colony maintenance and survival. Previous evidence suggests that naked mole-rats use olfaction for colony-level and individual recognition. To explicitly test a role for olfaction in naked mole-rat social decision making, we impaired function of the main olfactory system using zinc sulphate and measured performance in three behavioural paradigms: social dominance, social recognition and olfactory preference. We report that olfactory impairment significantly affected social dominance scores but that body mass was by far the most important variable for this behaviour. We confirm that naked mole-rats perform individual-level social recognition and that they prefer familiar versus unfamiliar colony olfactory cues. Although zinc sulphate decreased chemoinvestigatory behaviour in both the social recognition and olfactory preference paradigms, animals were still able to discriminate between stimuli, demonstrating that the main olfactory system is not necessary for social decision making in this species. A role for the accessory olfactory system is implied, although additional sensory cues, particularly auditory, must also be considered.
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olfaction and social cognition in eusocial naked mole rats Heterocephalus glaber
Animal Behaviour, 2015Co-Authors: Ilapreet Toor, David Clement, Erika N Carlson, Melissa M HolmesAbstract:Olfaction is the primary sensory modality involved in social cognition among rodents. Eusocial naked mole-rats live in large subterranean colonies with different castes and subcastes of individuals showing unique behavioural profiles. Thus, these animals are constantly faced with social decisions, which are key to colony maintenance and survival. Previous evidence suggests that naked mole-rats use olfaction for colony-level and individual recognition. To explicitly test a role for olfaction in naked mole-rat social decision making, we impaired function of the main olfactory system using zinc sulphate and measured performance in three behavioural paradigms: social dominance, social recognition and olfactory preference. We report that olfactory impairment significantly affected social dominance scores but that body mass was by far the most important variable for this behaviour. We confirm that naked mole-rats perform individual-level social recognition and that they prefer familiar versus unfamiliar colony olfactory cues. Although zinc sulphate decreased chemoinvestigatory behaviour in both the social recognition and olfactory preference paradigms, animals were still able to discriminate between stimuli, demonstrating that the main olfactory system is not necessary for social decision making in this species. A role for the accessory olfactory system is implied, although additional sensory cues, particularly auditory, must also be considered.
Jennifer U M Jarvis - One of the best experts on this subject based on the ideXlab platform.
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a case of natural queen succession in a captive colony of naked mole rats Heterocephalus glaber
African Zoology, 2013Co-Authors: L A Van Der Westhuizen, Jennifer U M JarvisAbstract:Naked mole-rats occur in large colonies where usually a single queen monopolizes reproduction. Queen succession occurs from within usually as a result of aggressive encounters with subordinate females that queue for reproductive succession following colony instability, which inevitably results in death of either the queen or the challenging conspecific. We monitored a queen succession following the death of the breeding male in a colony of the naked mole-rat, Heterocephalus glaber, prior to, during as well as after replacement of the original breeding female. The response of the pituitary luteotrophs was investigated in the non-reproductive females during this period of instability by the administration of endogenous gonadotrophin releasing hormone (GnRH) and evaluating the subsequent luteinising hormone (LH) response in the blood. Larger and older non-breeding females engaged in aggressive encounters that culminated in death. The new breeding successor which arose from within the colony was a large femal...
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burrowing and burrow patterns of east african mole rats tachyoryctes heliophobius and Heterocephalus
Journal of Zoology, 2010Co-Authors: Jennifer U M Jarvis, John B SaleAbstract:The burrowing behaviour and burrow patterns of the mole-rats Tachyoryctes (Family Rhizomyidae), Heliophobius and Heterocephalus (Family Bathyergidae) were compared. Remarkable similarities were found both in the method of digging and the basic burrow pattern of the three genera. Dissimilarities in burrow length can be attributed to the availability of food and the number of animals occupying one burrow system. Thus, the solitary Tachyoryctes, which eats a wide range of foods, has the shortest burrow system; while the colonial Heterocephalus, which eat a limited range of foods and live in arid regions, have very extensive burrow systems. All the mole-rats bite at the earth face with well developed incisors; collect the excavated soil with their fore and hind feet and push it behind them. Tachyoryctes differs from the bathyergids in then turning round and using one side of its face and one fore foot to push the excavated soil along the burrow and out onto the surface. The bathyergids back up to the soil and push with their hind feet. Tachyoryctes has a multi-purpose nest chamber used for sleeping, food storage and sanitary purposes; the bathyergids have a simple nest chamber used solely for sleeping, they do not store food but instead partly expose tubers in the foraging burrows and eat pieces from them when hungry. Differences between the bathyergids are largely attributable to their social structure; Heliophobius is solitary and Heterocephalus colonial. Digging and soil disposal are essentially similar but in Heterocephalus the various stages are taken by different members of the colony and a digging chain is established. Soil type and moisture content influence mound formation; Heterocephalus kicks out a spray of fine dry soil through an open hole. The other two mole-rats live in areas with higher soil moisture content and push out solid cores of soil.
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extraordinary life spans of naked mole rats Heterocephalus glaber
Journal of Zoology, 2002Co-Authors: Paul W Sherman, Jennifer U M JarvisAbstract:Senescence is the internal physiological deterioration that accompanies advancing age. Evolutionary hypotheses predict that rates of senescence should vary directly with extrinsic mortality and inversely with fecundity. If so, naked mole-rats (Heterocephalus glaber) should live a long time (senesce slowly) because in nature they inhabit heavily protected burrows, and large, old breeding females make disproportionate reproductive contributions. In addition H. glaber has an exceptionally low metabolic rate, which may reduce oxidative stress. We have maintained naked mole-rats in captivity since 1974. Here we report that individuals can live a very long time: many are alive after more than 20 years and some are 26 years old (and counting). Although we do not yet know how long naked mole-rats can live, they already are older than the maximum longevity of all but one of 156 rodent species that have been maintained in captivity from birth to death.
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The Naked Mole Rat--A New Record for the Oldest Living Rodent
Science of aging knowledge environment : SAGE KE, 2002Co-Authors: Rochelle Buffenstein, Jennifer U M JarvisAbstract:We report a new record for the world's longest-lived rodent, a male naked mole rat (Heterocephalus glaber). On the basis of his weight at capture, this animal was approximately 1 year old when collected near Mtito Andei, Kenya in July/August 1974. He died in April 2002, indicating that he lived for more than 28 years. As such, his life-span surpassed the previous longevity record for a rodent, which was held by a porcupine (Hystrix brachyura) that lived for 27 years and 4 months.
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investigation of numbers and motility of spermatozoa in reproductively active and socially suppressed males of two eusocial african mole rats the naked mole rat Heterocephalus glaber and the damaraland mole rat cryptomys damarensis
Reproduction, 1994Co-Authors: Chris G Faulkes, S N Trowell, Jennifer U M JarvisAbstract:Reproductive tracts and spermatozoa from reproductively active and reproductively suppressed non-breeding males from two species of eusocial African mole-rats Cryptomys damarensis and Heterocephalus glaber were examined. In two captive colonies of Heterocephalus glaber, reproductive tracts from seven non-breeding males removed from their colonies, and housed singly for 5-6 weeks to cause reproductive activation, were compared with reproductive tracts from seven non-breeding males. The body weight of the separated, reproductively active males increased significantly (P < 0.01), and the mean testis weights relative to body weight of the reproductively active males were significantly larger (P < 0.05) than those of non-breeding males. The number of spermatozoa, in one half of the reproductive tract, was higher in active males than in non-breeding males (mean +/- SEM: 8.59 x 10(6) +/- 2.69 x 10(6) versus 1.78 x 10(6) +/- 1.43 x 10(6), respectively; P < 0.05). In addition, six of the seven reproductively active males, but only two of seven non-breeding males, had motile spermatozoa. A total of 28 wild Cryptomys damarensis from two colonies were examined in the field. The testis weights relative to body weight of breeding males (n = 7) were higher than those of non-breeding males (n = 19; P < 0.01), but the number of spermatozoa did not differ significantly between the two groups (0.13 x 10(6) +/- 0.06 x 10(6), n = 7 versus 0.29 x 10(6) +/- 0.14 x 10(6), n = 21, respectively). Breeding and non-breeding males produced similar numbers of motile spermatozoa.(ABSTRACT TRUNCATED AT 250 WORDS)