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Jonathan J M Calede, John D Orcutt, Winifred A Kehl, Bill D Richards
The Clarkia lagerstätte (Latah Formation) of Idaho is well known for its beautifully preserved plant fossils as well as a fauna of insects and fish. Here we present the first known tetrapod fossil from these deposits. This specimen, recovered from the lower anoxic zone of the beds, is preserved as a carbonaceous film of a partial skeleton associated with a partial lower incisor and some tooth fragments. The morphology of the teeth indicates that the first tetrapod reported from Clarkia is a rodent. Its skeletal morphology as well as its bunodont and brachydont dentition suggests that it is a member of the squirrel family (Sciuridae)...
2018: PeerJ
Samantha M Logan, Kenneth B Storey
Background: Inflammation is generally suppressed during hibernation, but select tissues (e.g. lung) have been shown to activate both antioxidant and pro-inflammatory pathways, particularly during arousal from torpor when breathing rates increase and oxidative metabolism fueling the rewarming process produces more reactive oxygen species. Brown and white adipose tissues are now understood to be major hubs for the regulation of immune and inflammatory responses, yet how these potentially damaging processes are regulated by fat tissues during hibernation has hardly been studied...
2018: PeerJ
Ophélie Menant, Marie-Caroline Prima, Mélody Morisse, Fabien Cornilleau, Christian Moussu, Adeline Gautier, Hélène Blanchon, Maryse Meurisse, Philippe Delagrange, Yves Tillet, Elodie Chaillou
The periaqueductal gray (PAG) is a mesencephalic brain structure organised in subdivisions with specific anatomical connections with the rest of the brain. These connections support the different PAG functions and especially its role in emotion. Mainly described in territorial and predatory mammals, examination of the PAG connections suggests an opposite role of the ventral and the dorsal/lateral PAG in passive and active coping style, respectively. In mammals, the organisation of PAG connections may reflect the coping style of each species...
June 4, 2018: Brain Structure & Function
Jessica N Alvarez Guevara, Becky A Ball
Desert ecosystems are one of the fastest urbanizing areas on the planet. This rapid shift has the potential to alter the abundances and species richness of herbivore and plant communities. Herbivores, for example, are expected to be more abundant within urban desert remnant parks located within cities due to anthropogenic activities that concentrate food resources and reduce native predator populations. Despite this assumption, previous research conducted around Phoenix, AZ, USA has shown that top-down herbivory led to equally reduced plant biomass in both urban and outlying locations...
2018: PeerJ
Rudy Zozzoli, Mattia Menchetti, Emiliano Mori
Alien species of concern within the European Union have been recently listed and their populations need to be monitored, to plan addressed eradication or control programs. Therefore, the assessment of their presence should be rapidly carried out, particularly for elusive species or for those living at low densities. The Siberian chipmunk Eutamias sibiricus is a ground-dwelling squirrel, naturally distributed in northern and eastern Asia. Many introduced populations occur in Europe and Italy too. This species has been listed within the invasive species concern within the European Union and, thus, monitoring is mandatory to manage its potential range expansion...
May 30, 2018: Behavioural Processes
Benjamin S Sajdak, Brent A Bell, Tylor R Lewis, Gabriel Luna, Grayson S Cornwell, Steven K Fisher, Dana K Merriman, Joseph Carroll
Purpose: We examined outer retinal remodeling of the euthermic and torpid cone-dominant 13-lined ground squirrel (13-LGS) retina using optical coherence tomography (OCT) imaging and histology. Methods: Retinas and corneas of living 13-LGSs were imaged during euthermic and torpid physiological states using OCT. Retinal layer thickness was measured at the visual streak from registered and averaged vertical B-scans. Following OCT, some retinas were collected immediately for postmortem histologic comparison using light microscopy, immunofluorescence, or transmission electron microscopy...
May 1, 2018: Investigative Ophthalmology & Visual Science
Corinne Beier, Daniel Palanker, Alexander Sher
Proper function of the central nervous system (CNS) depends on the specificity of synaptic connections between cells of various types. Cellular and molecular mechanisms responsible for the establishment and refinement of these connections during development are the subject of an active area of research [1-6]. However, it is unknown if the adult mammalian CNS can form new type-selective synapses following neural injury or disease. Here, we assess whether selective synaptic connections can be reestablished after circuit disruption in the adult mammalian retina...
June 4, 2018: Current Biology: CB
Yasuhiro Yasutomi, Takahiro Tougan, Nobuko Arisue, Sawako Itagaki, Yuko Katakai, Yasuhiro Yasutomi, Toshihiro Horii
The asexual blood stages of the Plasmodium falciparum parasite are responsible for inducing the clinical symptoms and the most severe presentations of malaria infection that causes frequent mortality and morbidity in tropical and subtropical areas of the world, making the blood stages of infection a key target of new malaria treatment and prevention strategies. Progress towards the development of more effective treatment and prevention strategies has been hindered by the limited availability of infection models that permit the sequential analysis of blood stage parasites in vitro followed by in vivo analysis to confirm therapeutic benefits...
May 24, 2018: Parasitology International
Andrew N Rouble, Liam J Hawkins, Kenneth B Storey
The thirteen-lined ground squirrel (Ictidomys tridecemlineatus) is a well-known model for studying hibernation. While in a torpid state, these animals globally suppress energy expensive processes, while supporting specialized pathways necessary for survival. Lysine acetyltransferases (KATs) play a crucial role in modulating the expression and activity of a wide-variety of cellular pathways and processes, and therefore, may play a role during hibernation when the cell is shifting to an energy conservative, cytoprotective state...
May 2018: Journal of Thermal Biology
Ryan J Sprenger, Sherry A Tanumihardjo, Courtney C Kurtz
Retinoic acid, a bioactive metabolite of vitamin A, plays key roles in immune function and vision and adipose tissuedevelopment. Our goal was to study the effect of vitamin A deficiency in physiologic changes seen in hibernating 13-linedground squirrels (Ictidomys tridecemlineatus). In this study, we first developed a model of vitamin A deficiency that wasbased on published mouse models; we then examined the role of RA in the circannual cycle of and adipose accumulation inthis hibernating species. Gravid female ground squirrels began consuming a deficient diet during the last 2 wk of their 4-wkgestation; pups received the diet until they were 8 wk old, when severe symptoms of hypovitaminosis were observed, requiringthe animals' removal from the protocol...
May 25, 2018: Comparative Medicine
Francesca Santicchia, Ben Dantzer, Freya van Kesteren, Rupert Palme, Adriano Martinoli, Nicola Ferrari, Lucas Wauters Armand
1.Invasive alien species can cause extinction of native species through processes including predation, interspecific competition for resources, or disease-mediated competition. Increases in stress hormones in vertebrates may be associated with these processes and contribute to the decline in survival or reproduction of the native species. 2.Eurasian red squirrels (Sciurus vulgaris) have gone extinct across much of the British Isles and parts of Northern Italy following the introduction of North American invasive grey squirrels (Sciurus carolinensis)...
May 23, 2018: Journal of Animal Ecology
Maja Mielke, Jan Wölfer, Patrick Arnold, Anneke H van Heteren, Eli Amson, John A Nyakatura
Background: Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime...
2018: Zoological Letters
Sarah Louise Withey, Michelle R Doyle, Jack Bergman, Rajeev I Desai
Evidence suggests that the α4β2, but not the α7, subtype of nicotinic acetylcholine receptor (nAChR) plays a key role in mediating the behavioral effects of nicotine and related drugs. However, the importance of other nAChR subtypes remains unclear. The present studies were conducted to examine the involvement of nAChR subtypes by determining the effects of selected nicotinic agonists and antagonists in squirrel monkeys: a) responding for food-reinforcement; or b) discriminating the nicotinic agonist (+)-epibatidine (0...
May 21, 2018: Journal of Pharmacology and Experimental Therapeutics
Manouchehr Khazandi, Abd Al-Bar Al-Farha, Geoffrey W Coombs, Mark O'Dea, Stanley Pang, Darren J Trott, Ricardo R Aviles, Farhid Hemmatzadeh, Henrietta Venter, Abiodun D Ogunniyi, Andrew Hoare, Sam Abraham, Kiro R Petrovski
Methicillin-resistant coagulase-negative staphylococci (MRCoNS) have recently emerged as a significant cause of bovine mastitis worldwide. Here we describe the isolation of MRCoNS from cases of bovine mastitis from a single dairy farm in Australia. Fourteen CoNS isolates were identified as MRCoNS on the basis of having an oxacillin MIC of ≥0.5 μg/mL. The isolates were speciated as S. chromogenes (n = 1) S. fleurettii (n = 1), S. haemolyticus (n = 2), S. sciuri (n = 5), S. simulans (n = 1) S...
June 2018: Veterinary Microbiology
William Corrêa Tavares, Hector N Seuánez
Several rodent lineages independently acquired the ability to dig complex networks of tunnels where fossorial and subterranean species spend part or their whole life, respectively. Their underground lifestyles imposed harsh physiological demands, presumably triggering strong selective pressures on genes involved in energy metabolism like those coding for mitochondrial proteins. Moreover, underground lifestyles must have increased inbreeding and susceptibility to population bottlenecks as well as restricted migration, leading to small effective population size (Ne ) that, in turn, must have reduced the effectiveness of selection...
May 18, 2018: Mammalian Genome: Official Journal of the International Mammalian Genome Society
Dennis Tappe, Kore Schlottau, Daniel Cadar, Bernd Hoffmann, Lorenz Balke, Burkhard Bewig, Donata Hoffmann, Philip Eisermann, Helmut Fickenscher, Andi Krumbholz, Helmut Laufs, Monika Huhndorf, Maria Rosenthal, Walter Schulz-Schaeffer, Gabriele Ismer, Sven-Kevin Hotop, Mark Brönstrup, Anthonina Ott, Jonas Schmidt-Chanasit, Martin Beer
Limbic encephalitis is commonly regarded as an autoimmune-mediated disease. However, after the recent detection of zoonotic variegated squirrel bornavirus 1 in a Prevost's squirrel (Callosciurus prevostii) in a zoo in northern Germany, we retrospectively investigated a fatal case in an autoantibody-seronegative animal caretaker who had worked at that zoo. The virus had been discovered in 2015 as the cause of a cluster of cases of fatal encephalitis among breeders of variegated squirrels (Sciurus variegatoides) in eastern Germany...
June 2018: Emerging Infectious Diseases
Lanna M Desantis, Jeff Bowman, Mathilakath M Vijayan, Gary Burness
Southern flying squirrels have higher circulating cortisol levels than most vertebrates. However, regulation of tissue exposure to cortisol by the hormone's carrier protein, corticosteroid-binding globulin (CBG), appears to be altered due to lower-than-expected CBG expression levels, and a reduced affinity for cortisol. To assess the capacity of flying squirrels to regulate acute stress-mediated cortisol levels, we used the dexamethasone (DEX) suppression test followed by the adrenocorticotropic hormone (ACTH) stimulation test in both the breeding and non-breeding seasons, and quantified resultant changes in plasma cortisol and relative CBG levels...
May 12, 2018: General and Comparative Endocrinology
Yanhong Wei, Lingchen Gong, Weiwei Fu, Shenhui Xu, Zhe Wang, Jie Zhang, Er Ning, Hui Chang, Huiping Wang, Yunfang Gao
As a typical hibernator, the Daurian ground squirrel (Spermophilus dauricus) spends considerable time in a state of reduced activity with prolonged fasting. Despite this, they experience little muscle atrophy and have thus become an interesting anti-disuse muscle atrophy model. The IKKβ/NF-κB signaling pathway is significant to muscle atrophy due to the protein degradation resulting from the upregulation of the E3 ubiquitin ligase MuRF1. The current study showed that the IKKβ/NF-κB signaling pathway and MuRF1 maintained relatively steady mRNA and protein expression levels, with little muscle atrophy observed in the soleus (slow-twitch, SOL) or extensor digitorum longus (fast-twitch, EDL) during hibernation (HIB); however, mRNA expression significantly increased in the SOL and EDL muscle during interbout arousal (IBA), as did the MuRF1 mRNA level in the SOL and MuRF1 protein level in the EDL...
May 15, 2018: Journal of Cellular Physiology
M D Morin, D Lang-Ouellette, P J Lyons, N Crapoulet, P Morin
BACKGROUND: Mammalian hibernation is a fascinating phenomenon that involves multiple molecular and biochemical changes to proceed. While the molecular picture associated with torpor has become clearer in recent years, the function of non-coding RNAs, and especially of microRNAs, solicited during this process is not well understood. OBJECTIVE: To better characterize a signature of cold torpor-associated miRNAs in the hibernating thirteen-lined ground squirrel Ictidomys tridecemlineatus...
July 2017: Cryo Letters
Roberto Refinetti, G J Kenagy
Although inbred domesticated strains of rats and mice serve as traditional mammalian animal models in biomedical research, the nocturnal habits of these rodents make them inappropriate for research that requires a model with human-like diurnal activity rhythms. We conducted a literature review and recorded locomotor activity data from four rodent species that are generally considered to be diurnally active, the Mongolian gerbil ( Meriones unguiculatus), the degu ( Octodon degus), the African (Nile) grass rat ( Arvicanthis niloticus), and the antelope ground squirrel ( Ammospermophilus leucurus)...
January 1, 2018: Laboratory Animals
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