| blood respiratory properties in the naked mole rat heterocephalus glaber, a mammal of low body temperature. | respiratory properties of whole blood and hb solutions have been studied in heterocephalus glaber, a fossorial rodent, having a low body temperature (30.0-32.0 degrees c) and poor thermoregulatory ability. for comparison similar, measurements were made on laboratory mice, mus musculus. whole blood showed a distinctly higher o2 affinity for heterocephalus at both 30 and 37 degrees c.p50 values were 23.3 mm hg and 33.0 mm hg at 37 degrees c for heterocephalus and mus, respectively, while at 30 deg ... | 1976 | 14363 |
| tissue metabolism and enzyme activities in the rodent heterocephalus glaber, a poor temperature regulator. | 1. tissue oxygen uptake and enzyme activities were investigated in the naked mole rat, heterocephalus glaber, a mammal notable for its low body temperature and metabolism and poor temperature regulating ability. 2. q10 for o2 uptake of heterocephalus crude liver homogenates ranged from 1.91 for the temperature interval 25-30 degrees c to 1.76 within the range 30-38 degrees c, values similar to those reported for typical homoiotherms. 3. km pyruvate of lactate dehydrogenase in heart muscle had th ... | 1977 | 233774 |
| hearing and sound localization in blind mole rats (spalax ehrenbergi). | two blind mole rats were tested for their ability to detect and localize sound. the results indicate that blind mole rats have severely limited, and probably degenerate, auditory abilities. although their 60-db low-frequency hearing limit of 54 hz is within the range for other rodents, the highest frequency they can hear at a level of 60 db spl is only 5.9 khz, giving them the poorest high-frequency sensitivity yet observed in any mammal. in addition they have poor sensitivity as indicated by th ... | 1992 | 1429264 |
| nucleotide sequence variation in the mitochondrial 12s rrna gene and the phylogeny of african mole-rats (rodentia: bathyergidae). | mitochondrial dna (mtdna) sequence variation was examined in eight taxa of the african rodent family bathyergidae, as well as in two taxa representative of the old-world hystricognathid rodent families petromyidae and thryonomyidae. a total of 812 bp, constituting domains i-iii of the 12s ribosomal rrna gene, were compared for each taxon. the high levels of intrafamilial mtdna sequence divergence observed (average 16.8, range 3.5-23.2) support an ancient origin for the five genera, 20-38 mya. th ... | 1992 | 1552839 |
| caecal function provides the energy of fermentation without liberating heat in the poikilothermic mammal, heterocephalus glaber. | this paper presents the first report of a mammalian internal organ with a lower temperature than its abdominal surrounds. heterocephalus glaber, the naked mole-rat, is a poikilothermic mammal that leads a strictly subterranean existence and consumes a high proportion of fibre in its diet. the fermentation chamber in these animals appears to absorb rather than generate heat and the temperature in it was consistently 1.2 +/- 0.5 degrees c (n = 17) lower than rectal temperature. a caecum with a low ... | 1992 | 1613158 |
| queen activation of lazy workers in colonies of the eusocial naked mole-rat. | evolutionary conflicts of interest are expected to arise in genetically diverse social groups. in eusocial insect societies, a potential conflict exists between the queen and her workers over how active the workers should be, and evidence exists that queen aggression increases activity levels of her lazier workers. here i provide evidence that queen aggression (shoving) in laboratory colonies of the eusocial mammal, the naked mole-rat (heterocephalus glaber), is a convergently evolved manifestat ... | 1992 | 1614546 |
| the effect of diet on microfaunal population and function in the caecum of a subterranean naked mole-rat, heterocephalus glaber. | the effect of dietary fibre and starch content on digestibility, microfaunal population and caecal function was investigated in a subterranean mole-rat, heterocephalus glaber (rodentia). mole-rats were fed on a diet of either sweet potato (neutral-detergent fibre (ndf) 65 g/kg dry matter (dm), starch 638 g/kg dm) or carrot (ndf 157 g/kg dm, starch 258.7 g/kg dm) for 4 weeks. daily intake and faecal output were monitored. thereafter caecal microfaunal population, density and function were assesse ... | 1991 | 1645994 |
| social control of reproduction in breeding and non-breeding male naked mole-rats (heterocephalus glaber). | eight male naked mole-rats, from three colonies were studied in captivity. when non-breeding male naked mole-rats were removed from their colonies and paired with a non-breeding female, or removed and housed singly for 6 weeks before pairing with a female, concentrations of urinary testosterone and plasma luteinizing hormone (lh) increased significantly (p less than 0.05). concentration of these hormones were highest while the males were singly housed: urinary testosterone (mean +/- s.e.m.) incr ... | 1991 | 1787462 |
| cholecalciferol has no effect on calcium and inorganic phosphorus balance in a naturally cholecalciferol-deplete subterranean mammal, the naked mole rat (heterocephalus glaber). | naked mole rats, heterocephalus glaber, have no obvious source of cholecalciferol (d3) available to them, given their underground habitat and tubiferous diet. they have undetectable levels of 25-oh-d3 and as such appear to be naturally deplete in d3. the effect of an oral d3 supplement on mineral balance and homeostasis was therefore investigated. this d3 treatment did not affect circulating levels of ca2+ and inorganic phosphorus (p(i]. nor did d3 treatment affect mineral intake and absorption. ... | 1991 | 1851511 |
| morphine induces aggression but not analgesia in the naked mole-rat (heterocephalus glaber). | 1. the antinociceptive effect in the mole-rat of morphine (1, 10, 20 or 30 mg/kg) and nefopam (10 or 20 mg/kg) was studied. 2. in the hotplate test, morphine had no analgesic effect. a reduced response latency after morphine (10 and 20 mg/kg) could possibly be explained by hyperactivity and excited behaviour. 3. after morphine (10, 20 and 30 mg/kg) most of the animals died after fighting when kept in colony cages. aggressive behaviour and death was prevented by naloxone, or by keeping the animal ... | 1990 | 1980869 |
| social suppression of reproduction in male naked mole-rats, heterocephalus glaber. | to investigate possible anatomical and endocrine differences between breeding and non-breeding male naked mole-rats, 113 animals from 24 captive and 4 wild colonies were studied. while breeding males had larger reproductive tract masses compared to non-breeders relative to body mass (p less than 0.01), spermatogenesis was active in all of the non-breeding males examined histologically (n = 9) and spermatozoa were present in the epididymides. compared with non-breeders, breeding males had signifi ... | 1991 | 2013881 |
| lh responses of female naked mole-rats, heterocephalus glaber, to single and multiple doses of exogenous gnrh. | to investigate possible differential pituitary secretion of lh in breeding and non-breeding female naked mole-rats, the lh responses to administration of exogenous gnrh were measured in 55 females from 20 captive colonies. single doses of 0.1, 0.5 or 1.0 micrograms gnrh produced a significant rise in plasma lh concentrations 20 min after s.c. injection in breeding and non-breeding females at all doses (p less than 0.001). while at the highest dose of 1.0 microgram there was no difference in the ... | 1990 | 2197410 |
| brains of mole rats from africa and north america. | the total brain size and quantitative brain composition have been analyzed in four bathyergids and two geomyids in comparison with those in two spalacids. these mole rats show encephalic features corresponding to their phyletic descent from the cricetids. their diversity in brain organization suggests that, in spite of the seeming uniformity of their habitat the world over, they are narrowly adapted, a quantitative-to-qualitative relationship which only detailed eco-ethological information will ... | 1990 | 2309011 |
| dna "fingerprinting" reveals high levels of inbreeding in colonies of the eusocial naked mole-rat. | using the technique of dna fingerprinting, we investigated the genetic structure within and among four wild-caught colonies (n = 50 individuals) of a eusocial mammal, the naked mole-rat (heterocephalus glaber; rodentia: bathyergidae). we found that dna fingerprints of colony-mates were strikingly similar and that between colonies they were much more alike than fingerprints of non-kin in other free-living vertebrates. extreme genetic similarity within colonies is due to close genetic relationship ... | 1990 | 2320570 |
| social suppression of ovarian cyclicity in captive and wild colonies of naked mole-rats, heterocephalus glaber. | to investigate the endocrine cause of reproductive suppression in nonbreeding female naked mole-rats, animals from 35 colonies were studied in captivity. urinary and plasma progesterone concentrations were elevated in pregnant females (urine: 10.0-148.4 ng/mg cr, 27 samples from 8 females; plasma: 3.6-30.0 ng/ml, 5 samples from 5 females; days 21-40 of pregnancy) and cyclic breeding females (urine: 0.5-97.8 ng/mg cr, 146 samples from 7 females; plasma: less than 1.0-35.4 ng/ml, 25 samples from 7 ... | 1990 | 2325019 |
| experimental infection of the naked mole-rat, heterocephalus glaber, with leishmania donovani. | | 1988 | 3256107 |
| [rudimentary prehallux in heterocephalus glaber]. | | 1974 | 4460764 |
| eusociality in a mammal: cooperative breeding in naked mole-rat colonies. | laboratory observations on a field-collected colony of 40 heterocephalus have shown that only a single female breeds. the remaining individuals constitute two or three castes, each containing both sexes and distinguishable by size differences and the tasks they perform. these features, together with long life-spans, overlap of generations, cooperative brood care, and possible age polyethism provide parallels with the eusocial insects. | 1981 | 7209555 |
| the digging behavior and skin differentiations in heterocephalus glaber. | the topography and histology of the skin of the naked mole (heterocephalus glaber) have been correlated with its behavior. the integument is exceptionally loose, thereby reducing integumentary stresses when the animal is digging and moving in narrow tunnels. it also allows the position of the nasolabial sensory patch to change. this patch is exposed to mechanical stimuli when heterocephalus moves along the tunnel, but becomes partially shielded by a transient buccal evagination, the formation an ... | 1981 | 7241605 |
| pineal atrophy and other neuroendocrine and circumventricular features of the naked mole-rat, heterocephalus glaber (rüppell), a fossorial, equatorial rodent. | quantitative aspects of the microanatomy of the pineal gland and other neuroendocrine and circumventricular structures were studied in a small, reproductively suppressed, female naked mole-rat from central kenya, africa. the atrophic pineal is the smallest in absolute size (0.002135 mm3) of any so far described in a species of rodent, and in size relative to body weight is second only to that of another tropical species. the subcommissural organ and posterior collicular recess are also relativel ... | 1981 | 7288432 |
| behavioral and hormonal changes in female naked mole-rats (heterocephalus glaber) following removal of the breeding female from a colony. | colonies of naked mole-rats (heterocephalus glaber) contain a single dominant, breeding female, or "queen", which suppresses reproduction in subordinate females. in this study, the queen and breeding male were removed from a colony at brookfield zoo. we examined behavioral and endocrine changes in the remaining colony females. behavioral observations were conducted weekly and urine samples were collected beginning 3 months prior to the planned removal of animals. prior to the removal, only the q ... | 1995 | 7557925 |
| intestinal calcium transport in mole-rats (cryptomys damarensis and heterocephalus glaber) is independent of both genomic and non-genomic vitamin d mediation. | the role of vitamin d in mineral uptake in the gastrointestinal tract (git) of mole-rats (heterocephalus glaber and cryptomys damarensis; family bathyergidae), animals with a naturally impoverished vitamin d status, was investigated. we measured relative rates of passage of radioactive markers, mode of calcium (ca) uptake, paracellular movement and the opening of voltage-sensitive ca channels (vsccs) along the git with and without oral vitamin d3 supplementation. the ratio of relative absorption ... | 1995 | 7576599 |
| effects of pethidine, acetylsalicylic acid, and indomethacin on pain and behavior in the mole-rat. | the antinociceptive and behavioral effects of pethidine (10, 20, or 30 mg/kg), acetylsalicylic acid (200, 400, or 600 mg/kg) and indomethacin (20, 40, or 50 mg/kg) in the naked mole-rat was studied in the hot-plate test. instead of inducing analgesia, pethidine caused a dose-dependent reduction in response latency. sensorimotor impairment and aggressive behavior were also observed following administration of pethidine (20 or 30 mg/kg). all animals receiving pethidine (30 mg/kg) died following fi ... | 1993 | 7639825 |
| vitamin d3 intoxication in naked mole-rats (heterocephalus glaber) leads to hypercalcaemia and increased calcium deposition in teeth with evidence of abnormal skin calcification. | naked mole-rats have no access to obvious sources of vitamin d and therefore have an impoverished vitamin d status. in an investigation into the effects of vitamin d supplementation, inadvertently supraphysiological doses of 130,000 times the normal dose of vitamin d were administered. within 5 days animals appeared lethargic, with reduced food intake. all but one of the seven animals were killed and blood was collected. plasma vitamin d metabolites 25(oh)d and 1,25(oh)2d and calcium were determ ... | 1995 | 7657155 |
| socializing with non-naked mole rats. | | 1995 | 7824913 |
| vitamin d hydroxylases and their regulation in a naturally vitamin d-deficient subterranean mammal, the naked mole rat (heterocephalus glaber). | the vitamin d hormone 1,25-dihydroxyvitamin d3 (1,25(oh)2d3) is generated by a series of hydroxylation steps in the liver and kidneys. we investigated whether naturally vitamin d-deficient subterranean mammals (naked mole rats, heterocephalus glaber) employ the same enzymatic pathways, and whether these are regulated in a similar manner to that established for other mammals. vitamin d3-25-hydroxylase in the liver and both 25-hydroxyvitamin d3-1-hydroxylase and 25-hydroxyvitamin d3-24 hydroxylase ... | 1993 | 7852893 |
| 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). | 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 weigh ... | 1994 | 8021857 |
| sleep arrhythmia in the eusocial naked mole-rat. | | 1994 | 8058104 |
| kidney concentrating ability of a subterranean xeric rodent, the naked mole-rat (heterocephalus glaber). | the naked mole-rat (heterocephalus glaber) is a strictly subterranean mammal inhabiting the arid zones of north-east africa. these animals have no access to free water and water balance thus might be facilitated by regulating renal water loss. the urinary concentrating ability of the naked mole-rat was determined using five dietary manipulations in which both water and salt content were altered. "control" animals (n = 7) received a high quality protein cereal mixed to a thin paste with water (1 ... | 1994 | 8195471 |
| vitamin d receptors in a naturally vitamin d-deficient subterranean mammal, the naked mole rat (heterocephalus glaber): biochemical characterization. | 1,25-dihydroxyvitamin d3 (1,25(oh)2d3), the hormonally active metabolite of vitamin d3 interacts with its nuclear/cytosolic receptor to induce biological responses in target tissues. naked mole rats appear to be naturally deficient in vitamin d. the questions arise whether these animals possess the 1,25(oh)2d3 receptor (vdr) and whether they are capable of responding to 1,25(oh)2d3 via receptor-mediated pathways. various tissues (intestine, kidney, harderian glands, and skin) were examined for t ... | 1993 | 8224760 |
| ultrastructural study of the testis of non-breeding naked mole-rat (heterocephalus glaber, ruppell). | the testicular structure of the wild caught naked mole rat was studied. it comprises of a large volume of lipid-rich interstitial cells of leydig among which are few scattered seminiferous tubules. in addition, the interstitial cells possess elongated mitochondria and vast network of smooth endoplasmic reticulum (ser). the golgi apparatus (ga) apparently is not conspicuous or well developed. all stages of spermatogenesis occur in the seminiferous tubules although the mature forms (secondary sper ... | 1993 | 8250273 |
| evidence that primer pheromones do not cause social suppression of reproduction in male and female naked mole-rats (heterocephalus glaber). | the role of chemical cues in mediating the reproductive suppression of nonbreeding males and females in colonies of naked mole-rats (heterocephalus glaber) was examined by comparing reproductive activation in isolated nonbreeders with that of isolated nonbreeders maintained in olfactory and gustatory contact with their parent colony. animals were either removed from their colony and paired directly with a member of the opposite sex from the same colony, or were removed, housed singly for 40 days ... | 1993 | 8283442 |
| calcium and inorganic phosphorus metabolism in naked mole rats heterocephalus glaber is only indirectly affected by cholecalciferol. | naked mole rats seem to be naturally deficient in cholecalciferol yet exhibit net calcium and inorganic phosphorus absorption efficiencies that approach a physiological maximum (i.e., exceed 94%). oral supplementation with cholecalciferol therefore does not markedly enhance the efficiency of gastrointestinal absorption of these minerals, but rather exerts indirect effects on mineral metabolism by increasing food intake (1.7x) from 3.6 +/- 0.4 to 6.2 +/- 0.3 g/100 g body wt day-1. this, in turn, ... | 1993 | 8381370 |
| cholecalciferol supplementation alters gut function and improves digestibility in an underground inhabitant, the naked mole rat (heterocephalus glaber), when fed on a carrot diet. | naked mole rats (heterocephalus glaber) lead a strictly subterranean existence and appear to be naturally deficient in cholecalciferol (d3). oral supplementation with d3 (ds) led to a 1.8-fold increase in food intake and the associated enlargement (1.4-fold) of the caecum. the effect of ds, and the concomitant increase in food intake, on caecal fermentation efficiency when animals were fed on a carrot-based diet was determined by measuring the rate of both gas production and short-chain fatty ac ... | 1993 | 8384476 |
| the formalin test in the naked mole-rat (heterocephalus glaber): analgesic effects of morphine, nefopam and paracetamol. | the present experiments were initiated to study the effects of morphine, nefopam and paracetamol in the naked mole-rat, a hairless rodent that lives in subterranean colonies of up to 300, following the inability to demonstrate morphine analgesia in the hot-plate test in the rodent. the formalin test was used. injection of 20 microliters 10% formalin produced two periods of high licking and pain behaviour, the early (0-5 min) and the late phase (15-60 min). morphine (10 or 20 mg/kg), nefopam (10 ... | 1993 | 8422579 |
| effects of codeine, naproxen and dexamethasone on formalin-induced pain in the naked mole-rat. | a dilute solution of formalin (20 microliters of 10% formalin) was injected subcutaneously in the dorsal right hind paw of the naked mole-rat. the injection of the dilute formalin produced two periods of pain behaviour, the early (0-5 minutes) and the late phase (25-60 minutes). these were quantified as the total time spent licking the injected paw. codeine phosphate (10, 25 or 50 mg kg-1) significantly reduced pain behaviour in both the early and late phase. codeine administration also induced ... | 1993 | 8453032 |
| degenerate hearing and sound localization in naked mole rats (heterocephalus glaber), with an overview of central auditory structures. | behavioral tests of absolute sensitivity and sound localization in african naked mole rats show that, despite their communal social structure and large vocal repertoire, their hearing has degenerated much like that of other subterranean species. first, their ability to detect sound is limited, with their maximum sensitivity being only 35 db (occurring at 4 khz). second, their high-frequency hearing is severely limited, with their hearing range (at 60 db sound pressure level [spl]) extending from ... | 1993 | 8514919 |
| a dispersive morph in the naked mole-rat. | close inbreeding is known for a variety of small mammal species for which a high probability of mortality during dispersal makes helping and delayed maturation a relatively secure fitness option. prolonged inbreeding, however, is usually associated with lowered fitness, and it has been shown that most highly inbred small mammals and social insects have inbreeding-avoidance mechanisms that promote some degree of outbreeding. however, previous field and laboratory research on the naked mole-rat (h ... | 1996 | 8602260 |
| naked mole-rats on the move. behavioural ecology. | the discovery of a disperser morph in naked mole-rat colonies has revealed the first possible outbreeding mechanism for this unusual mammal, and provides another remarkable parallel to the eusocial insects. | 1996 | 8805352 |
| acoustic communication underground: vocalization characteristics in subterranean social mole-rats (cryptomys sp., bathyergidae). | in captive adult zambian mole-rats 14 different sounds (13 true vocalizations) have been recorded during different behavioural contexts. the sound analysis revealed that all sounds occurred in a low and middle frequency range with main energy below 10 khz. the majority of calls contained components of 1.6-2 khz, 0.63-0.8 khz, and/or 5-6.3 khz. the vocalization range thus matched well the hearing range as established in other studies. the frequency content of courtship calls in two species of zam ... | 1997 | 9048440 |
| catecholaminergic innervation of interscapular brown adipose tissue in the naked mole-rat (heterocephalus glaber). | the thermogenic potential of the interscapular brown fat pad in the naked mole-rat heterocephalus glaber, that exhibits poikilothermic thermal responses to changing temperatures is reported. histological and ultrastructural study of the brown fat pad showed that it consists of layers of skeletal muscle interposed between the layers of brown adipose tissue with both unilocular and multilocular adipocytes. large numbers of mitochondria were present between and around the lipid droplets of these ce ... | 1997 | 9147219 |
| combined olfactory contact with the parent colony and direct contact with nonbreeding animals does not maintain suppression of ovulation in female naked mole-rats (heterocephalus glaber). | the study investigated the role of odor cues from two naked mole-rat colonies, in conjunction with behavioral cues from nonbreeding colony members, in maintaining suppression of ovulation in subordinate female naked mole-rats isolated from the two parent colonies. four high ranking nonbreeding female naked mole-rats were removed from their respective parent colonies and singly housed in separate burrow systems. for a 64-day period, the removed females were maintained in daily odor contact with t ... | 1997 | 9213141 |
| micro- and macrogeographical genetic structure of colonies of naked mole-rats heterocephalus glaber. | patterns of genetic structure in eusocial naked mole-rat populations were quantified within and among geographically distant populations using multilocus dna fingerprinting and mitochondrial dna (mtdna) sequence analysis. individuals within colonies were genetically almost monomorphic, sharing the same mtdna control region haplotype and having coefficients of band sharing estimated from dna fingerprints ranging from 0.93 to 0.99. family analysis of a hybrid captive colony of naked mole-rats with ... | 1997 | 9226945 |
| dominance and queen succession in captive colonies of the eusocial naked mole-rat, heterocephalus glaber. | naked mole-rat colonies exhibit a high reproductive skew, breeding being typically restricted to one female (the 'queen') and one to three males. other colony members are reproductively suppressed, although this suppression can be reversed following the removal or death of the queen. we examined dominance and queen succession within captive colonies to investigate the relationship between urinary testosterone and cortisol, dominance rank and reproductive status; and to determine if behavioural a ... | 1997 | 9263466 |
| ecological constraints drive social evolution in the african mole-rats. | the african mole-rats (family bathyergidae) are subterranean hystricomorph rodents occurring in a variety of habitats and displaying levels of sociality which range from solitary to eusocial, making them a unique mammalian taxonomic group to test ecological influences on sociality. here, we use an extensive dna-based phylogeny and comparative analysis to investigate the relationship between ecology, sociality and evolution within the family. mitochondrial cytochrome-b and 12s rrna trees reveal t ... | 1997 | 9404025 |
| measurements of behavior in the naked mole-rat after intraperitoneal implantation of a radio-telemetry system. | the naked mole-rat (heterocephalus glaber) is a unique fossorial mammal that is eusocial, object blind, and virtually poikilothermic. this animal is an ideal model to examine questions pertaining to the thermoregulatory aspects of sleep/wake cycles and other circadian events. however, the monitoring of mammalian sleep usually involves implanting permanent electrodes into the skull which are linked to a counter-weighted cable apparatus. this is not a viable option for h. glaber because of the tun ... | 1998 | 9696320 |
| hormonal and behavioural correlates of male dominance and reproductive status in captive colonies of the naked mole-rat, heterocephalus glaber. | naked mole-rat colonies are societies with a high reproductive skew, breeding being restricted to one dominant female (the 'queen') and 1-3 males. other colony members of both sexes are reproductively suppressed. experimental removal of breeding males allowed us to investigate the relationship between urinary testosterone and cortisol, dominance rank, and male reproductive status. dominance rank was strongly correlated with body weight, age, and urinary testosterone titres in males. no relations ... | 1998 | 9721687 |
| skin morphology and its role in thermoregulation in mole-rats, heterocephalus glaber and cryptomys hottentotus. | the skin structure of 2 bathyergid rodents, the naked mole-rat (heterocephalus glaber) and the common mole-rat (cryptomys hottentotus) is compared, to investigate whether thermoregulatory differences may be attributed to different skin features. histological and ultrastructural studies of the dorsal skin of these closely related species show morphological and structural similarities but differences in the degree of skin folding, thickness of the integument and dermal infrastructure were evident. ... | 1998 | 10029182 |
| factors influencing metabolic rate in naked mole-rats (heterocephalus glaber). | naked mole-rats (heterocephalus glaber) are fossorial, eusocial mammals that live in colonies averaging about 70 individuals. metabolic regulation is of particular interest in this species because it is one of only two naturally occurring small mammals that are hairless. further, relative to other small mammals, naked mole-rats exhibit low body temperature (tb) and weak capacity to maintain tb above the ambient temperature (ta). the present study examined effects of ta, norepinephrine (ne), and ... | 1999 | 10357434 |
| kin discrimination and female mate choice in the naked mole-rat heterocephalus glaber. | naked mole-rats are fossorial, eusocial rodents that naturally exhibit high levels of inbreeding. persistent inbreeding in animals often results in a substantial decline in fitness and, thus, dispersal and avoidance of kin as mates are two common inbreeding avoidance mechanisms. in the naked mole-rat evidence for the former has recently been found. here we address the latter mechanism by investigating kin recognition and female mate choice using a series of choice tests in which the odour, socia ... | 1999 | 10584337 |
| evidence from intron 1 of the nuclear transthyretin (prealbumin) gene for the phylogeny of african mole-rats (bathyergidae). | a 900- to 1100-bp fragment encompassing intron 1 of the nuclear transthyretin (prealbumin) gene was examined in 12 taxa of old world hystricognath rodents of the families bathyergidae, petromuridae, thryonomyidae, and hystricidae. within the bathyergidae, heterocephalus glaber (naked mole-rat) was basal, and the other east african species, heliophobius argenteocinereus (silvery mole-rat), was sister to a southern african clade containing bathyergus, cryptomys, and georychus (dune, common, and ca ... | 2000 | 10991798 |
| morphological castes in a vertebrate. | morphological specialization for a specific role has, until now, been assumed to be restricted to social invertebrates. herein we show that complete physical dimorphism has evolved between reproductives and helpers in the eusocial naked mole-rat. dimorphism is a consequence of the lumbar vertebrae lengthening after the onset of reproduction in females. this is the only known example of morphological castes in a vertebrate and is distinct from continuous size variation between breeders and helper ... | 2000 | 11087866 |
| cold-induced changes in thyroid function in a poikilothermic mammal, the naked mole-rat. | cold acclimation induces very divergent responses in thyroid function in reptiles and mammals reflective of their different thermoregulatory modes. naked mole-rats, unlike other small mammals, are unable to effectively employ endothermy and are operatively poikilotherms. we therefore investigated changes in their thyroid status with chronic cold exposure. under simulated burrow conditions, free thyroxine (t(4); 0.39 +/- 0.09 ng/dl) and thyroid stimulating hormone (tsh; 1.12 +/- 0.56 microiu/ml) ... | 2001 | 11124146 |
| circadian rhythms of locomotor activity in naked mole-rats (heterocephalus glaber). | a wide variety of organisms exhibit various circadian rhythms in their behavior and physiology. circadian rhythms are regulated by internal clocks that are generally entrained primarily by the environmental light:dark (l:d) cycle. there have been few studies of circadian rhythms in fossorial species that inhabit an environment where day-night variations are minimal and where exposure to light occurs infrequently. in this study, circadian patterns of wheel-running activity were examined in naked ... | 2000 | 11134679 |
| circadian rhythms of body temperature and metabolic rate in naked mole-rats. | body temperature (t(b)) and metabolic rate (o(2) consumption) were measured continuously in naked mole-rats. circadian rhythms were observed for both parameters. body temperature increased at the end of the light phase in a 12l:12d cycle in three of four animals. the remaining animal exhibited a freerunning rhythm of t(b). when animals had access to running wheels, the time of elevated t(b) coincided closely with the time of increased running wheel activity. rhythms of t(b) continued following r ... | 2000 | 11134680 |
| family values: group dynamics and social control of reproduction in african mole-rats. | to exploit ecological niches where constraints have favoured selection for group living and cooperation, both vertebrates and invertebrates have evolved elaborate social systems. in mammals, numerous divergent taxa have converged at similar solutions to these ecological challenges (such as food distribution and predator avoidance), culminating in the social insect-like behaviour of the naked mole-rat. characteristically, breeding is partitioned unequally in such groups, resulting in a 'reproduct ... | 2001 | 11245941 |
| perineal muscles and motoneurons are sexually monomorphic in the naked mole-rat (heterocephalus glaber). | naked mole-rats are eusocial mammals that live in colonies with a single breeding female and one to three breeding males. all other members of the colony, known as subordinates, are nonreproductive and exhibit few sex differences in behavior or genital anatomy. this raises questions about the degree of sexual differentiation in subordinate naked mole-rats. the striated perineal muscles associated with the phallus [the bulbocavernosus (bc), ischiocavernosus (ic), and levator ani (la) muscles], an ... | 2002 | 11920726 |
| somatosensory cortex dominated by the representation of teeth in the naked mole-rat brain. | we investigated naked mole-rat somatosensory cortex to determine how brain areas are modified in mammals with unusual and extreme sensory specializations. naked mole-rats (heterocephalus glaber) have numerous anatomical specializations for a subterranean existence, including rows of sensory hairs along the body and tail, reduced eyes, and ears sensitive to low frequencies. however, chief among their adaptations are behaviorally important, enlarged incisors permanently exterior to the oral cavity ... | 2002 | 11943853 |
| naked mole-rats: unique opportunities and husbandry challenges. | the naked mole-rat is a relative newcomer to biomedical and behavioral studies. the authors review this unusual rodent's uses in research, husbandry, reproduction, and common diseases. | 2002 | 11984550 |
| eusociality in african mole-rats: new insights from patterns of genetic relatedness in the damaraland mole-rat (cryptomys damarensis). | after the discovery of eusociality in the naked mole-rat, it was proposed that inbreeding and high colony relatedness in this species were the major underlying factors driving cooperative breeding in african molerats. by contrast, field and laboratory studies of the eusocial damaraland mole-rat (cryptomys damarensis) have raised the possibility that this species is an obligate outbreeder, although the build-up of inbreeding over several generations could still occur. using microsatellite markers ... | 2002 | 12028759 |
| localization of the cytochrome p450 side-chain cleavage enzyme in the inactive testis of the naked mole-rat. | spermatogenesis was histologically examined in non-breeding male of the naked mole rat (heterocephalus glaber) using a light microscopy. spermatogonia, spermatocytes and spermatids were confirmed in the seminiferous tubules. however, the spermatogenesis was disordered, and many spermatocytes and spermatids were sloughing. sperms could not be seen in the lumen of the tubules. the characteristic accumulation of interstitial cells was the most noteworthy. in the immunohistochemistry for cytochrome ... | 2002 | 12130795 |
| pretender punishment induced by chemical signalling in a queenless ant. | animal societies are stages for both conflict and cooperation. reproduction is often monopolized by one or a few individuals who behave aggressively to prevent subordinates from reproducing (for example, naked mole-rats, wasps and ants). here we report an unusual mechanism by which the dominant individual maintains reproductive control. in the queenless ant dinoponera quadriceps, only the alpha female reproduces. if the alpha is challenged by another female she chemically marks the pretender who ... | 2002 | 12214231 |
| thermogenic changes with chronic cold exposure in the naked mole-rat (heterocephalus glaber). | the naked mole-rat (heterocephalus glaber) lives communally in a thermally buffered underground habitat. here, it relies primarily on ectothermic (behavioral) mechanisms to maintain body temperature (t(b)). outside this milieu, it is unable to effectively regulate t(b) and t(b) tracks that of ambient temperature (t(a)). although naked mole-rats, in their natural habitat have little need for cold-tolerance, we questioned whether or not thermogenic capacity would change with prolonged (>1 year) ex ... | 2002 | 12443938 |
| prolonged longevity in naked mole-rats: age-related changes in metabolism, body composition and gastrointestinal function. | aging is characterized by declines in all physiological processes and concomitant changes in body composition. age-related changes in metabolism, body composition and gastrointestinal function were investigated in naked mole-rats (heterocephalus glaber), rodents that exhibit extended longevity. maximum lifespan of these 40 g rodents (>27 year) is approximately 9 times greater than predicted allometrically. we investigated changes in basal metabolic rate (bmr), body composition and intestinal glu ... | 2002 | 12443939 |
| somatosensory organization and behavior in naked mole-rats: ii. peripheral structures, innervation, and selective lack of neuropeptides associated with thermoregulation and pain. | african naked mole-rats are subterranean rodents that have a robust orienting response to stimulation of unique vibrissa-like body hairs that are widely spaced over an otherwise hairless skin. to determine whether these large body hairs have a specialized organization similar to facial vibrissae, the structure and innervation of facial vibrissa follicles, body hair follicles, and intervening skin in naked mole-rats was compared with that in rats and a furred african mole-rat species (the common ... | 2003 | 12926019 |
| somatosensory organization and behavior in naked mole-rats i: vibrissa-like body hairs comprise a sensory array that mediates orientation to tactile stimuli. | orientation guided by mechanosensory stimuli is a fundamental behavior that has been analyzed most effectively in simple systems, but has been difficult to assess in mammals. this study demonstrates that sparsely distributed sensory 'hairs' on the body of naked mole-rats provide an ideal detector array for the assessment of touch guided orienting behavior. naked mole-rats are fully subterranean rodents that are functionally blind and lack fur. about 40 tactile hairs (resembling facial vibrissae) ... | 2003 | 12966188 |
| the naked mole rat--a new record for the oldest living rodent. | 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. | 2002 | 14602989 |
| [husbandry appropriate to the species for african naked mole rats (heterocephalus glaber)]. | it is reported about the keeping of a group of naked mole rats (heterocephalus glaber; nine males and 13 females), which had been imported from kenya in 1996. the animals are kept in a small experimental room without windows at permanent darkness, 30 degrees c environmental temperature and relative humidity above 70%. they live in a glass container, to which a collapsible system of plexiglass tubes is connected. the moles are daily fed ad libitum with different fresh root crops. until today thre ... | 2003 | 14633051 |
| phylogeographical patterns of genetic divergence and speciation in african mole-rats (family: bathyergidae). | 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 cl ... | 2004 | 14871365 |
| postnatal development of the eye in the naked mole rat (heterocephalus glaber). | the naked mole rat (heterocephalus glaber) is a subterranean rodent whose eyes are thought to be visually nonfunctional and as such is an ideal animal with which to pursue questions in evolutionary developmental biology. this report is the first in-depth study on the development and morphology of the naked mole rat eye. using standard histological analysis and scanning and transmission electron microscopy, we describe the structural features of the eye. we further report on the morphological cha ... | 2004 | 15052660 |
| unusual cone and rod properties in subterranean african mole-rats (rodentia, bathyergidae). | we have determined the presence of spectral cone types, and the population densities of cones and rods, in subterranean mole-rats of the rodent family bathyergidae, for which light and vision seems of little importance. most mammals have two spectral cone types, a majority of middle- to long-wave-sensitive (l-) cones, and a minority of short-wave-sensitive (s-)cones. we were interested to see whether the subterranean bathyergids show the same pattern. in three species, ansell's mole-rat cryptomy ... | 2004 | 15066151 |
| colony structure and parentage in wild colonies of co-operatively breeding damaraland mole-rats suggest incest avoidance alone may not maintain reproductive skew. | colonies of co-operatively breeding african mole-rats have traditionally been thought to be composed of a single breeding female, one or two breeding males, and their offspring. in the naked mole-rat (heterocephalus glaber), the occurrence of facultative inbreeding means incest avoidance cannot prevent reproduction in subordinate group members, and physiological suppression of reproductive function by the breeding female occurs in both sexes. in contrast, previous studies of captive colonies of ... | 2004 | 15245409 |
| identification of retinal neurons in a regressive rodent eye (the naked mole-rat). | the retina consists of many parallel circuits designed to maximize the gathering of important information from the environment. each of these circuits is comprised of a number of different cell types combined in modules that tile the retina. to a subterranean animal, vision is of relatively less importance. knowledge of how circuits and their elements are altered in response to the subterranean environment is useful both in understanding processes of regressive evolution and in retinal processin ... | 2004 | 15259562 |
| adaptive size modification by dominant female meerkats. | in species of cooperative insects that live in large groups, selection for increased fecundity has led to the evolution of an increased body size among female reproductives, but whether this is also true of cooperative vertebrates is unknown. among vertebrates, morphological modification of female breeders has only been documented in a single species; in naked mole rats (heterocephalus glaber), acquisition of alpha status is associated with a significant increase in body size through an elongati ... | 2004 | 15341161 |
| the pancreas of the naked mole-rat (heterocephalus glaber): an ultrastructural and immunocytochemical study of the endocrine component of thermoneutral and cold acclimated animals. | endocrine cell distribution within the islets of langerhans may vary both between species and under different energetically demanding conditions such as cold acclimation. the naked mole-rat, heterocephalus glaber, lacking an effective insulatory pelage, is effectively a poikilotherm, yet it shows a typical mammalian cold-acclimation response by substantially increasing food intake to meet higher energy requirements when housed at lower temperatures. the endocrine component of the pancreas of the ... | 2004 | 15560867 |
| diverse aging rates in metazoans: targets for functional genomics. | aging, or senescence, has typically been measured by demographic analysis, which has its merits but is blind to key aspects of functional development and deterioration. if one uses demographic analyses, however, the approach providing most insight is the analysis of age-specific mortality. the continuing increase in dna sequencing power combined with emerging computational techniques will allow in the near future detailed investigation of mechanisms of aging in diverse species beyond the typical ... | 2005 | 15610761 |
| features of visual function in the naked mole-rat heterocephalus glaber. | 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 approximately 10% and approximately 50% that of gerbil, respectively. levels per unit retin ... | 2005 | 15647925 |
| crossing the taxonomic divide: conflict and its resolution in societies of reproductively totipotent individuals. | reproduction in groups may be unequal, with one or a few individuals monopolizing direct reproduction assisted by nonbreeding helpers. in social insects this has frequently led to a pronounced queen-worker dichotomy and a loss of reproductive totipotency among workers. however, in some invertebrate and all vertebrate societies, all or most individuals remain reproductively totipotent. in these groups, conflicts of interest over reproduction are potentially greatest. here, we synthesize previous ... | 2005 | 15715844 |
| plasticity of the cortical dentition representation after tooth extraction in naked mole-rats. | naked mole-rats (heterocephalus glaber) have a large cortical representation of their behaviorally important front teeth, accounting for 30% of primary somatosensory cortex (si). here we investigated the plasticity of this dental representation after the extraction of a single lower tooth. the representation of the contralateral lower incisor normally accounts for approximately 15% of somatosensory cortex in mole-rats. in five mole-rats the lower right incisor was extracted on either postnatal d ... | 2005 | 15776439 |
| antioxidants do not explain the disparate longevity between mice and the longest-living rodent, the naked mole-rat. | the maximum lifespan of naked mole-rats (nmrs; heterocephalus glaber) is greater than that of any other rodent. these hystricognaths survive in captivity >28 years, eight-times longer than similar-sized mice. the present study tested if nmrs possess superior antioxidant defenses compared to mice and if age-related interspecies changes in antioxidants were evident. activities of cu/zn superoxide dismutase (cu/zn, sod), mn sod, catalase and cellular glutathione peroxidase (cgpx) were measured in l ... | 2005 | 16087218 |
| the naked mole-rat: a new long-living model for human aging research. | tremendous variation in maximum life span among species overshadows modest increases in longevity resulting from experimental manipulation. few aging studies focus on long-lived mammals even though these species may expose mechanisms involved in resisting aging. naked mole-rats (nmrs approximately 35 grams) are the longest-living (>28.3 years) rodents known. this review describes their biology and potential use in aging research. lifestyle features concur with most evolutionary theories with the ... | 2005 | 16339321 |
| central visual system of the naked mole-rat (heterocephalus glaber). | naked mole-rats are fossorial rodents native to eastern africa that spend their lives in extensive subterranean burrows where visual cues are poor. not surprisingly, they have a degenerated eye and optic nerve, suggesting they have poor visual abilities. however, little is known about their central visual system. to investigate the organization of their central visual system, we injected a neuronal tracer into the eyes of naked mole-rats and mice to compare the neural structures mediating vision ... | 2006 | 16419086 |
| the use of a novel and simple method of revealing neural fibers to show the regression of the lateral geniculate nucleus in the naked mole-rat (heterocephalus glaber). | the lateral geniculate nucleus (lg) is an important subcortical nucleus in the visual system. it receives primary projections from the retina and relays these to central visual structures. although there are studies on the retina and visual cortex of animals with regressed vision, little is known about the lg in such animals. the strictly subterranean naked mole-rat (heterocephalus glaber) has markedly reduced visual acuity with concomitant pronounced changes in the visual cortex. we used a nove ... | 2006 | 16483554 |
| organization of somatosensory cortical areas in the naked mole-rat (heterocephalus glaber). | multiunit electrophysiology was combined with histological analysis of cortical sections to investigate the organization of somatosensory areas in the naked mole-rat. we provide new details for the organization of primary somatosensory cortex (s1) and identify cortical modules and barrels that correspond to the representations of different body parts. in addition, details of the location and organization of secondary somatosensory cortex (s2) are reported, and evidence for a third somatosensory ... | 2006 | 16485289 |
| influence of gonadal sex hormones on behavioral components of the reproductive hierarchy in naked mole-rats. | naked mole-rats (heterocephalus glaber) are fossorial, eusocial rodents that live in colonies which typically include 60-80 individuals. generally, only one of the females and 1-3 of the males in a colony are reproductives. the reproductives engage in mutual genital nuzzling behavior that is rarely exhibited by subordinates (non-reproductives). thus, genital nuzzling may represent a mechanism of bonding and/or specific recognition between reproductive individuals. we investigated whether gonadal ... | 2006 | 16537080 |
| population coding strategies and involvement of the superior colliculus in the tactile orienting behavior of naked mole-rats. | even simple behaviors of vertebrates are typically generated by the concerted action of large numbers of brain cells. however, the mechanisms by which groups of neurons work together as functional populations to guide behavior remain largely unknown. one of the major model systems for exploring these mechanisms has been mammalian visuomotor behavior. we describe here experiments that establish a new model system for analyzing the sensory control of behavior by neuronal populations using a mammal ... | 2006 | 16603320 |
| cortical, callosal, and thalamic connections from primary somatosensory cortex in the naked mole-rat (heterocephalus glaber), with special emphasis on the connectivity of the incisor representation. | we investigated the distribution of cortical, callosal, and thalamic connections from the primary somatosensory area (s1) in naked mole-rats, concentrating on lower incisor and forelimb representations. a neuronal tracer (wga-hrp) was injected into the center of each respective representation under guidance from microelectrode recordings of neuronal activity. the locations of cells and terminals were determined by aligning plots of labeled cells with flattened cortical sections reacted for cytoc ... | 2006 | 16652365 |
| a stereotaxic atlas of the brain of the naked mole-rat (heterocephalus glaber). | 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 s ... | 2006 | 16793211 |
| complex evolution of x and y autosomal translocations in the giant mole-rat, cryptomys mechowi (bathyergidae). | cross-species chromosome painting was used to determine homologous chromosomal regions between two species of mole-rat, the naked mole-rat, heterocephalus glaber (2n = 60), and the giant mole-rat, cryptomys mechowi (2n = 40), using flow-sorted painting probes representative of all but two of the h. glaber chromosomal complement. in total 43 homologous regions were identified in the c. mechowi genome. eight h. glaber chromosomes are retained in toto in c. mechowi, and 13 produce two or more signa ... | 2006 | 16964575 |
| breeding status affects motoneuron number and muscle size in naked mole-rats: recruitment of perineal motoneurons? | naked mole-rats live in large colonies and exhibit a strict reproductive hierarchy. each colony has one breeding female and one to three breeding males; all other individuals are nonreproductive subordinates. subordinates show a remarkable lack of sex differences in behavior and anatomy, but can become reproductive if removed from the colony. we recently reported that the striated perineal muscles and their innervating motoneurons, which are sexually dimorphic in all other mammals examined to da ... | 2006 | 16967507 |
| high oxidative damage levels in the longest-living rodent, the naked mole-rat. | oxidative stress is reputed to be a significant contributor to the aging process and a key factor affecting species longevity. the tremendous natural variation in maximum species lifespan may be due to interspecific differences in reactive oxygen species generation, antioxidant defenses and/or levels of accrued oxidative damage to cellular macromolecules (such as dna, lipids and proteins). the present study tests if the exceptional longevity of the longest living (> 28.3 years) rodent species kn ... | 2006 | 17054663 |
| oxidation-resistant membrane phospholipids can explain longevity differences among the longest-living rodents and similarly-sized mice. | underlying causes of species differences in maximum life span (mls) are unknown, although differential vulnerability of membrane phospholipids to peroxidation is implicated. membrane composition and longevity correlate with body size; membranes of longer-living, larger mammals have less polyunsaturated fatty acid (pufa). we determined membrane phospholipid composition of naked mole-rats (mls > 28.3 years) and similar-sized mice (mls = 3-4 years) by gas-liquid chromatography to assess if the appr ... | 2006 | 17077193 |
| comparison of endothelial function, o2-* and h2o2 production, and vascular oxidative stress resistance between the longest-living rodent, the naked mole rat, and mice. | vascular aging is characterized by decreased nitric oxide (no) bioavailability, oxidative stress, and enhanced apoptotic cell death. we hypothesized that interspecies comparative assessment of vascular function among rodents with disparate longevity may offer insight into the mechanisms determining successful vascular aging. we focused on four rodents that show approximately an order of magnitude range in maximum longevity (ml). the naked mole rat (nmr; heterocephalus glaber) is the longest-livi ... | 2006 | 17090784 |
| stimulation of mu and delta opioid receptors induces hyperalgesia while stimulation of kappa receptors induces antinociception in the hot plate test in the naked mole-rat (heterocephalus glaber). | the antinociceptive effects of highly selective mu (damgo), delta (dpdpe) and kappa (u-50488 and u-69593) opioid agonists were evaluated following intraperitoneal (i.p.) administration in the naked mole-rat. a hot plate test set at 60 degrees c was used as a nociceptive test and the latency to the stamping of the right hind paw (response latency) was used as the end-point. damgo (5-10 mg/kg) and dpdpe (2.5-5 mg/kg) caused a naloxone-reversible significant decrease in the mean response latency. s ... | 2006 | 17113929 |
| disparate patterns of age-related changes in lipid peroxidation in long-lived naked mole-rats and shorter-lived mice. | a key tenet of the oxidative stress theory of aging is that levels of accrued oxidative damage increase with age. differences in damage generation and accumulation therefore may underlie the natural variation in species longevity. we compared age-related profiles of whole-organism lipid peroxidation (urinary isoprostanes) and liver lipid damage (malondialdehyde) in long living naked mole-rats [maximum lifespan (mls) > 28.3 years] and shorter-living cb6f1 hybrid mice (mls approximately 3.5 years) ... | 2006 | 17129214 |
| distribution of vasopressin in the brain of the eusocial naked mole-rat. | naked mole-rats are eusocial rodents that live in large subterranean colonies in which one queen breeds with one to three males. all other animals are nonbreeding subordinates. the external features of male and female subordinates, including their genitalia, are remarkably monomorphic, as is their behavior. because vasopressin (vp) is associated with social behaviors and sex differences in other species, its distribution in naked mole-rats was of interest. we used immunohistochemistry to examine ... | 2007 | 17183541 |
| growth-deficient vomeronasal organs in the naked mole-rat (heterocephalus glaber). | 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 vomeronas ... | 2007 | 17188655 |
| growing out of a caste--reproduction and the making of the queen mole-rat. | naked mole-rats have a eusocial colony structure consisting of non-reproductive workers and a reproductively active caste where a single, dominant queen and 1-3 males produce all of the offspring. well-established queens have elongated bodies that characterize their caste. worker females retain the ability to transform into queens, however the trigger and time course for this physical transformation remain a mystery. here, we show a direct link between periods of pregnancy and vertebral lengthen ... | 2007 | 17210962 |
| savanna chimpanzees, pan troglodytes verus, hunt with tools. | although tool use is known to occur in species ranging from naked mole rats [1] to owls [2], chimpanzees are the most accomplished tool users [3-5]. the modification and use of tools during hunting, however, is still considered to be a uniquely human trait among primates. here, we report the first account of habitual tool use during vertebrate hunting by nonhumans. at the fongoli site in senegal, we observed ten different chimpanzees use tools to hunt prosimian prey in 22 bouts. this includes im ... | 2007 | 17320393 |
| a new coordinate system for rodent brain and variability in the brain weights and dimensions of different ages in the naked mole-rat. | traditionally, the skull landmarks, i.e., bregma, lambda, and the interaural line, are the origins of the coordinate system for almost all rodent brain atlases. the disadvantages of using a skull landmark as an origin are: (i) there are differences among individuals in the alignment between the skull and the brain; (ii) the shapes of sutures, on which a skull landmark is determined, are different for different animals; (iii) the skull landmark is not clear for some animals. recently, the extreme ... | 2007 | 17320969 |