The naked mole-rat is the longest living rodent with a maximum lifespan exceeding 28 years. In addition to its longevity, mole-rats have an extraordinary resistance cancer as tumors never been observed in these rodents. Furthermore, we show that combination of activated Ras and SV40 LT fails induce robust anchorage-independent growth cells, while it readily transforms mouse fibroblasts. mechanisms responsible for were unknown. Here fibroblasts display hypersensitivity contact inhibition,...

Comparative studies amongst extant species are one of the pillars evolutionary neurobiology. In 20th century, most comparative remained restricted to analyses brain structure volume and surface areas, besides estimates neuronal density largely limited cerebral cortex. Over last 10 years, we have amassed data on numbers neurons other cells that compose entirety (subdivided into cortex, cerebellum, rest brain) 39 mammalian spread over 6 clades, as well their densities. Here provide entire...

Summary In multicellular organisms, telomerase is required to maintain telomere length in the germline but dispensable soma. Mice, for example, express somatic and tissues, while humans almost exclusively germline. As a result, when telomeres of human cells reach critical enter irreversible growth arrest called replicative senescence. Replicative senescence believed be an anticancer mechanism that limits cell proliferation. The difference between mice led hypothesis repression has evolved as...

Brain size scales as different functions of its number neurons across mammalian orders such rodents, primates, and insectivores. In we have previously shown that, a sample 6 species, from mouse to capybara, the cerebral cortex, cerebellum remaining brain structures increase in faster than they gain neurons, with an accompanying decrease neuronal density these [Herculano-Houzel et al.: Proc Natl Acad Sci USA 2006;103:12138–12143]. Important questions are whether scaling rules within order...

SUMMARY Integumentary sensory organs (ISOs) are densely distributed on the jaws of crocodilians and body scales members families Crocodilidae Gavialidae. We examined distribution, anatomy, innervation response properties ISOs face documented related behaviors for an alligatorid (Alligator mississippiensis) a crocodylid (Crocodylus niloticus). Each (roughly 4000 in A. mississippiensis 9000 C. niloticus) was innervated by networks afferents supplying multiple different mechanoreceptors....

Integration of bilateral sensory information is fundamental to stimulus localization in auditory systems and depth perception vision, but the role stereo olfactory cues remains obscure. Here it shown that blind, eastern American moles combine serial sampling with nasal localize odorants. Blocking one nostril causes err direction open strongest effect within 4–5 cm stimulus. Nostril block does not severely disrupt more distant navigation towards odorants a T-maze nor prevent animals from...

Abstract Lateral somatosensory areas have not been explored in detail rats, and theories on the organization of this region are based largely anatomical tracing experiments. We investigated topography by using microelectrode recordings, which were related to flattened cortical sections processed for cytochrome oxidase (CO). Two lateral identified, each containing a complete representation body. A larger, more medial formed mirror image S1 along rostrocaudal axis head corresponding previously...

Abstract The nose of thestar‐nosed mole consists a star‐like array 22 fleshy appendages that radiate from the nostrils and are moved about to explore environment. surface each appendage, or ray, is densely packed with bulbous receptor organs (Eimer's organs) highly responsive tactile stimulation. Here, we report these rays have corresponding morphological specializations in somatosensory cortex. Using stain for metabolic enzyme, cytochrome oxidase (CO), reveal subdivisions cortex, disclosed...

Large, long-lived species experience more lifetime cell divisions and hence a greater risk of spontaneous tumor formation than smaller, short-lived species. are thus expected to evolve elaborate suppressor systems. In previous work, we showed that telomerase activity coevolves with body mass, but not lifespan, in rodents: is repressed the somatic tissues large rodent remains active small ones. Without activity, telomeres replicating cells become progressively shorter until, at some critical...

Fish are elusive prey with a short-latency escape behavior--the C-start--initiated to either the left or right by "race" between 2 giant Mauthner neurons in fish brainstem. Water disturbances usually excite ipsilateral neuron, which massively excites contralateral motor neurons, resulting rapid turn away from striking predators. Here, it is reported that tentacled snakes (Erpeton tentaculatus) exploit this normally adaptive circuitry feinting their body, triggering cell furthest head...

Electric eels can incapacitate prey with an electric discharge, but the mechanism of eel’s attack is unknown. Through a series experiments, I show that eel high-voltage discharges activate motor neurons, and hence muscles, allowing to remotely control their target. Eels prevent escape in free-swimming using high-frequency volleys induce immobilizing whole-body muscle contraction (tetanus). Further, when are hidden, emit periodic two or three cause massive involuntary twitch, revealing prey’s...

Significance Electric eels are shown to leap from the water directly electrify threats. This shocking behavior likely allows electric defend themselves during Amazonian dry season, when they may be found in small pools and danger of predation. The results support Alexander von Humboldt’s story attacking horses that had been herded into a muddy pool season 1800. finding highlights sophisticated behaviors have evolved concert with eel’s powerful electrical organs.

We determined the somatotopy of face and oral cavity representation in cortical area 3b New World owl monkeys squirrel monkeys. Area is apparent as a densely myelinated strip brain sections cut parallel to surface flattened cortex. A narrow myelin-light septum that we have termed "hand-face septum" separates hand from more lateral mouth representation. The further divided into series myelin-dense ovals. show three ovals adjacent correspond upper face, lip, chin plus lower whereas or four...

Eleven fleshy appendages, or rays, surround each of the nostrils star-nosed mole. Each ray is covered with tactile sensory organs, and represented in cortex by a stripe tissue visible brain sections processed for cytochrome oxidase. Here we report that 11th, ventral behavioral focus nose. This preferentially used to explore prey items touch, behavior pattern similar use fovea visual system. After first contacted any nasal ray, subsequent touches are centered on 11th ray. Although small has...

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 hairs along the body tail, reduced eyes, ears sensitive low frequencies. However, chief among their adaptations behaviorally important, enlarged incisors permanently exterior oral cavity that used digging,...

Abstract Lateral line sensory receptors and their cranial nerves in axolotls arise from a dorsolateral series of placodes, including the octaval placode, that gives rise to inner ear nerve. Anterodorsal anteroventral placodes occur rostral placode give anterodorsal lateral electroreceptors mechanoreceptors snout, cheek, lower jaw. Middle, supratemporal, posterior caudal similarly named nerves, occipital region head, trunk neuromasts. All except elongate, forming ridges, following genesis...

American water shrews (Sorex palustris) are aggressive predators that feed on a variety of terrestrial and aquatic prey. They often forage at night, diving into streams ponds in search food. We investigated how locate submerged prey using high-speed videography, infrared lighting, stimuli designed to mimic Shrews attacked brief movements, indicating motion is an important cue used detect active or escaping also bit, retrieved, attempted eat model fish made silicone preference other objects...

Ampullary organ electroreceptors excited by weak cathodal electric fields are used for hunting both cartilaginous and non-teleost bony fishes. Despite similarities of neurophysiology innervation, their embryonic origins remain controversial: fish ampullary organs derived from lateral line placodes, whereas a neural crest origin has been proposed electroreceptors. This calls into question the homology in two lineages jawed vertebrates. Here, we test hypothesis that placodes form fishes...

Here we provide the most comprehensive study to date on cranial ossification sequence in Lipotyphla, group which includes shrews, moles and hedgehogs. This unique group, encapsulates diverse ecological modes, such as terrestrial, subterranean, aquatic lifestyles, is used examine evolutionary lability of osteogenesis investigate modularity development. An acceleration developmental timing vomeronasal complex has occurred common ancestor moles. However, nasal bone shifted late more terrestrial...

Cortical organization was examined in five shrew species. In three species, Blarina brevicauda, Cryptotis parva, and Sorex palustris, microelectrode recordings were made cortex to determine the of sensory areas. then related flattened sections processed for cytochrome oxidase or myelin reveal architectural borders. An additional two species (Sorex cinereus longirostris) with visible cortical subdivisions based on histology alone analyzed without electrophysiological mapping. A single basic...