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1.
Eur J Histochem ; 66(1)2022 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35057584

RESUMO

G-protein-coupled receptor 41 (GPR41) and G-protein-coupled receptor 43 (GPR43) are important short-chain fatty acids (SCFAs) receptors. Previous studies indicated that GPR41 and GPR43 are involved in the secretion of gastrointestinal peptides, and glucose and lipid metabolism, and are closely related to obesity and type II diabetes, and other diseases. The purpose of the study was to explore the relationship between the GPR41 and GPR43 and seasonal breeding, and provide new prospects for further exploring the nutritional needs of breeding. We identified the localization and expression levels of GPR41 and GPR43 in the colon of the wild ground squirrels (Spermophilus dauricus) both in the breeding season and non-breeding season. The histological results revealed that the lumen diameter of the colon had obvious seasonal changes, and the diameter of the colonic lumen in the non-breeding season was larger than that in the breeding season. Immunohistochemical staining suggested GPR41 and GPR43 have expressed in the simple layer columnar epithelium. In addition, compared with the breeding season, the mRNA and protein expression levels of GPR41 and GPR43 in the colon were higher during the non-breeding season. In general, these results indicated GPR41 and GPR43 might play a certain role in regulating seasonal breeding.


Assuntos
Diabetes Mellitus Tipo 2 , Sciuridae , Animais , Colo , Ácidos Graxos Voláteis/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Sciuridae/metabolismo , Estações do Ano
2.
Curr Biol ; 32(12): R605-R607, 2022 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-35728537

RESUMO

Pra et al. provide an overview of ground squirrels and the physiological adaptations these animals have evolved to contend with harsh climates.


Assuntos
Hibernação , Sciuridae , Adaptação Fisiológica , Animais , Clima , Sciuridae/fisiologia
3.
Sensors (Basel) ; 22(12)2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35746126

RESUMO

Squirrel-cage induction motors are increasingly displaying a broken rotor bar fault, which represents both a technical problem and an economic problem. After confirming that the broken rotor bars do not affect the normal start-up and basic working performance of the squirrel-cage induction motor, this paper focuses on the loss and efficiency changes of the motor brought about by the broken rotor bar fault. Using finite element simulation and experimentation, various losses like stator copper loss, iron loss, rotor copper loss, mechanical loss and additional losses, total loss and efficiency are obtained. By combining price and cost factors, the cost-effective measures that can be taken after the occurrence of different degrees of broken bars are evaluated here to provide guidance for correctly handling this problem.


Assuntos
Algoritmos , Sciuridae , Animais , Simulação por Computador , Cobre
4.
Oecologia ; 199(2): 301-312, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35713713

RESUMO

Telomeres are specialized non-coding DNA sequences located at the end of chromosomes and that protect genetic information. Telomere loss over lifespan is generally viewed as a phenomenon associated with aging in animals. Recently, telomere elongation after hibernation has been described in several mammals. Whether this pattern is an adaptation to repair DNA damage caused during rewarming from torpor or if it coevolved as a mechanism to promote somatic maintenance in preparation for the upcoming reproductive effort remains unclear. In a longitudinal study measuring telomere length using buccal swabs, we tested if telomere elongation was related to reproductive success in wild adult female Columbian ground squirrels (Urocitellus columbianus) that were monitored from emergence from hibernation to the end of the reproductive season. We found three key results. First, female telomere length increased at the start of the breeding season, both in breeding and non-breeding individuals. Second, post-emergence telomere lengthening was unrelated to female future reproductive output. Third, telomere length decreased in breeding females during lactation, but remained stable in non-breeding females over a similar period. Within breeders, telomeres shortened more in females producing larger and heavier litters. We concluded that telomere lengthening after hibernation did not constrain immediate female reproductive capacities. It was more likely to be part of the body recovery process that takes place after hibernation. Telomere erosion that occurs after birth may constitute a physiological cost of female reproduction.


Assuntos
Homeostase do Telômero , Telômero , Animais , Feminino , Estudos Longitudinais , Masculino , Reprodução/fisiologia , Sciuridae/genética
5.
Am Nat ; 200(1): 1-16, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35737995

RESUMO

AbstractIndividual diet specialization (IDS) is widespread and can affect the ecological and evolutionary dynamics of populations in significant ways. Extrinsic factors (e.g., food abundance) and individual variation in energetic needs, morphology, or physiology have been suggested as drivers of IDS. Behavioral traits like exploration and boldness can also impact foraging decisions, although their effects on IDS have not yet been investigated. Specifically, variation among individuals in exploratory behavior and their position along the exploration/exploitation trade-off may affect their foraging behavior, acquisition of food items, and home range size, which may in turn influence the diversity of their diet. Here, we analyzed stable carbon and nitrogen isotopes in hair of wild eastern chipmunks, Tamias striatus, to investigate the influence of individual differences in exploration on IDS. We found that exploration profile, sex, and yearly fluctuations in food availability explained differences in the degree of dietary specialization and in plasticity in stable carbon and stable nitrogen over time. Thus, consistent individual differences in exploration can be an important driver of within-population niche specialization and could therefore affect within-species competition. Our results highlight the need for a more thorough investigation of the mechanisms underlying the link between individual behavioral differences and diet specialization in wild animal populations.


Assuntos
Dieta , Individualidade , Animais , Carbono , Comportamento de Retorno ao Território Vital , Isótopos de Nitrogênio , Sciuridae
6.
Physiol Biochem Zool ; 95(4): 288-301, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35588474

RESUMO

AbstractMammals entering hibernation undergo drastic reductions in metabolic rate and body temperature (Tb; to as low as ∼2% of euthermic metabolic rate and 1°C to -2°C). Although ventilation (V˙E) is also greatly reduced in hibernating ground squirrels, their relative ventilatory response (%ΔV˙E) to increases in inspired CO2 (∼400% increase to 7% CO2) dwarfs that of euthermic squirrels (∼60% increase). On the basis of data from earlier studies on hypothermic animals, we hypothesized that this switch in apparent ventilatory sensitivity was the result of the change in state (from euthermic to hibernating) and not due to the change in core Tb. Thus, we used whole-body plethysmography to assess the hypercapnic ventilatory response (HCVR) in thirteen-lined ground squirrels in steady-state hibernation at 20°C, 15°C, 10°C, 7°C, and 5°C. With the transition into hibernation as Tb fell, the breathing pattern became irregular and then episodic. Total V˙E and the oxygen consumption rate (V˙O2) decreased progressively as Tb fell. Hibernating squirrels with a core Tb of 20°C increased V˙E by 150% from normocapnic levels when given 7% CO2 to breathe, while squirrels with a Tb of 7°C increased V˙E by 650% when exposed to the same inspired CO2. When Tb was cooled from 7°C to 5°C, however, the increase in the HCVR fell to 450% and was associated with a rise in V˙O2 and total V˙E. These results reveal progressive changes in breathing pattern and the HCVR with decreasing Tb and suggest that the effects of hibernation state may be Tb dependent. V˙E did not fall in proportion to metabolic rate, and the HCVR increased progressively in both absolute terms and relative terms until a Tb of 7°C, both of which potentially constrain the extent of the metabolic suppression.


Assuntos
Hibernação , Animais , Dióxido de Carbono/metabolismo , Hibernação/fisiologia , Respiração , Sciuridae/fisiologia , Temperatura
7.
Parasit Vectors ; 15(1): 174, 2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35597994

RESUMO

BACKGROUND: Among live wild mammals adapted to urban and peri-urban habitats in Europe, members of the families Felidae, Mustelidae and Sciuridae deserve special attention as pathogen reservoirs because all of these families include members that are kept as pets. We report here the results of our study on two important groups of tick-borne protozoan parasites in ticks and tissues of wild cats, mustelids and red squirrels. METHODS: DNA was extracted from the tissues of carnivores (wild cats, mustelids; n = 16) and red squirrels (n = 4), as well as from ixodid ticks (n = 89) collected from these hosts. These DNA extracts were screened for piroplasms and Hepatozoon spp. using conventional PCR analysis and sequencing. In addition, 53 pooled samples of 259 questing Haemaphysalis concinna ticks were evaluated for the presence of Hepatozoon DNA, followed by phylogenetic analyses. RESULTS: One wild cat was found to be coinfected with Cytauxzoon europaeus and a new genotype of Hepatozoon felis, and two additional wild cats were infected with H. felis from a different phylogenetic group. In mustelids, Hepatozoon martis and two further Hepatozoon genotypes were detected. The latter clustered separately, close to others reported from eastern Asia. In addition, Hepatozoon sciuri was detected in red squirrels. Morphologic and molecular analyses verified eight tick species. One wild cat was infected with a H. felis genotype that was significantly different from that in Ixodes ricinus females infesting this cat. Only three pools of questing H. concinna nymphs tested positive for Hepatozoon, one of which contained H. martis. CONCLUSIONS: This study provides the first evidence of the occurrence of any Cytauxzoon species and of three Hepatozoon species in Hungary. In addition to H. martis, two further mustelid-associated Hepatozoon genotypes were detected, one of which was new in terms of phylogenetic and broader geographical contexts. This may be the first indication that H. felis genotypes from both of its phylogenetic groups occur in Europe. This also appears to be the first evidence of H. felis and C. europaeus coinfection in felids in Europe, and of autochthonous H. felis infection in wild cats north of the Mediterranean Basin. New tick-host associations were also observed in this study. Based on the results, H. felis and H. martis might survive transstadially in I. ricinus and H. concinna, respectively.


Assuntos
Apicomplexa , Eucoccidiida , Felis , Haemosporida , Ixodes , Ixodidae , Mustelidae , Parasitos , Piroplasmida , Animais , Apicomplexa/genética , Eucoccidiida/genética , Feminino , Hungria/epidemiologia , Filogenia , Piroplasmida/genética , Sciuridae
8.
Artigo em Inglês | MEDLINE | ID: mdl-35506980

RESUMO

Eleven Gram-negative, curved and S-shaped, oxidase activity positive, catalase activity negative bacterial isolates recovered from faeces of Anatolian ground squirrel (Spermophilus xanthoprymnus) in the city of Kayseri, Turkey, were subjected to a polyphasic taxonomic study. Results of a genus-specific PCR revealed that these isolates belonged to the genus Helicobacter. The 16S rRNA gene sequence analysis revealed that the 11 isolates had over 99 % sequence identity with each other and were most closely related to Helicobacter ganmani CMRI H02T with 97.0-97.1 % identity levels and they formed a novel phylogenetic line within the genus Helicobacter. Faydin-H64 and Faydin-H70T strains were subjected to gyrA and atpA gene and whole genome sequence analyses. These two Helicobacter strains formed separate phylogenetic clades, divergent from other known Helicobacter species. The DNA G+C content and genome size of the strain Faydin-H70T were 35.3 mol% and 1.7 Mb, respectively. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain Faydin-H70T and its close phylogenetic neighbour H. winghamensis ATCC BAA-430T were determined as 81.7 and 34.9 %, respectively. Pairwise sequence comparison showed that it was closely related to H. ganmani CMRI H02T however it shared the highest ANI and dDDH values with H. winghamensis ATCC BAA-430T. The data obtained from the polyphasic taxonomy approach, including phenotypic characterization and whole-genome sequences, revealed that these strains represent a novel species within the genus Helicobacter, for which the name Helicobacter turcicus sp. nov., is proposed with Faydin-H70T as the type strain (=DSM 112556T=LMG 32335T).


Assuntos
Helicobacter , Sciuridae , Animais , Técnicas de Tipagem Bacteriana , Composição de Bases , Catalase/genética , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Filogenia , RNA Ribossômico 16S/genética , Sciuridae/genética , Análise de Sequência de DNA , Turquia
9.
Sci Rep ; 12(1): 8264, 2022 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-35585229

RESUMO

Nowadays, remote sensing is being increasingly applied in ecology and conservation, and even underground animals can successfully be studied if they leave clear signs of their presence in the environment. In this work, by combining a field study, analysis of high-resolution aerial images, and machine learning techniques, we investigated the interspecies relationships of two small burrowing mammals: the spotted souslik Spermophilus suslicus and the European mole Talpa europaea. The study was conducted for 3 years (2018-2020) at a 105-ha grass airfield where both species coexist (Poland). Both field studies and the analysis of aerial imagery showed that, in the period of low population numbers, the souslik avoided coexistence with the European mole, and the presence of the mole was found to reduce the area of the habitat suitable for the souslik. The presence of other burrowing species may be an important element in the habitat selectivity of the souslik, but this has not yet been included in the conservation guidelines for this species. We discuss the contribution of our results to the knowledge of the ecology of burrowing mammals and their interspecies relationships. We also assess the possibility of using remote sensing and deep learning methods in ecology and conservation of small burrowing mammals.


Assuntos
Aprendizado Profundo , Toupeiras , Animais , Ecossistema , Tecnologia de Sensoriamento Remoto , Sciuridae
10.
Sensors (Basel) ; 22(9)2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35591060

RESUMO

In this article, we propose to determine the dynamic model of a squirrel-cage induction motor from a reduced amount of information. An adaptive observer is also built from this model in order to obtain a speed estimation and to perform rotor fault monitoring by Tacholess Order Tracking (TOT). We also propose a generalization of the notion of angular sampling in order to adapt to this type of defect. The procedure is validated in the laboratory on a test bench dedicated to the study of rotor bar defects.


Assuntos
Algoritmos , Sciuridae , Animais , Registros
11.
12.
Commun Biol ; 5(1): 492, 2022 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-35606540

RESUMO

Hibernation involves prolonged intervals of profound metabolic suppression periodically interrupted by brief arousals to euthermy, the function of which is unknown. Annual cycles in mammals are timed by a photoperiodically-regulated thyroid-hormone-dependent mechanism in hypothalamic tanycytes, driven by thyrotropin (TSH) in the pars tuberalis (PT), which regulates local TH-converting deiodinases and triggers remodeling of neuroendocrine pathways. We demonstrate that over the course of hibernation in continuous darkness, arctic ground squirrels (Urocitellus parryii) up-regulate the retrograde TSH/Deiodinase/TH pathway, remodel hypothalamic tanycytes, and activate the reproductive axis. Forcing the premature termination of hibernation by warming animals induced hypothalamic deiodinase expression and the accumulation of secretory granules in PT thyrotrophs and pituitary gonadotrophs, but did not further activate the reproductive axis. We suggest that periodic arousals may allow for the transient activation of hypothalamic thyroid hormone signaling, cellular remodeling, and re-programming of brain circuits in preparation for the short Arctic summer.


Assuntos
Hibernação , Animais , Hibernação/fisiologia , Iodeto Peroxidase , Sciuridae/fisiologia , Hormônios Tireóideos , Tireotropina
13.
J Comp Physiol B ; 192(3-4): 529-540, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35503574

RESUMO

Omega 3 polyunsaturated fatty acids (PUFAs) are well-documented for their influence on health and weight loss. Recent studies indicate omega 3 PUFAs may exert a negative impact on cellular stress and physiology in some hibernators. We asked if physiological stress indicators, lipid peroxidation and mass gain in Arctic Ground Squirrels (AGS) were negatively influenced by naturally occurring dietary omega 3 PUFA levels compared to omega 3 PUFA levels found in common laboratory diets. We found plasma fatty acid profiles of free-ranging AGS to be high in omega 3 PUFAs with balanced omega 6:3 ratios, while standard laboratory diets and plasma of captive AGS are high in omega 6 and low in omega 3 PUFAs with higher omega 6:3 ratios. Subsequently, we designed a diet to mimick free-range AGS omega 6:3 ratios in captive AGS. Groups of wild-caught juvenile AGS were either fed: (1) Mazuri Rodent Chow (Standard Rodent chow, 4.95 omega 6:3 ratio), or (2) balanced omega 6:3 chow (Balanced Diet, 1.38 omega 6:3). AGS fed the Balanced Diet had plasma omega 6:3 ratios that mimicked plasma profiles of wild AGS. Balanced Diet increased female body mass before hibernation, but did not influence levels of cortisol in plasma or levels of the lipid peroxidation product 4-HNE in brown adipose tissue. Overall, as the mass gain is critical during pre-hibernation for obligate hibernators, the results show that mimicking a fatty acid profile of wild AGS facilitates sex-dependent mass accumulation without increasing stress indicators.


Assuntos
Ácidos Graxos Ômega-3 , Ácidos Graxos Ômega-6 , Animais , Ácidos Graxos , Ácidos Graxos Insaturados , Feminino , Sciuridae/fisiologia , Estresse Fisiológico
14.
J Med Entomol ; 59(3): 1053-1059, 2022 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-35380675

RESUMO

Prairie dogs in the western United States experience periodic epizootics of plague, caused by the flea-borne bacterial pathogen Yersinia pestis. An early study indicated that Oropsylla hirsuta (Baker), often the most abundant prairie dog flea vector of plague, seldom transmits Y. pestis by the classic blocked flea mechanism. More recently, an alternative early-phase mode of transmission has been proposed as the driving force behind prairie dog epizootics. In this study, using the same flea infection protocol used previously to evaluate early-phase transmission, we assessed the vector competence of O. hirsuta for both modes of transmission. Proventricular blockage was evident during the first two weeks after infection and transmission during this time was at least as efficient as early-phase transmission 2 d after infection. Thus, both modes of transmission likely contribute to plague epizootics in prairie dogs.


Assuntos
Ctenocephalides , Infestações por Pulgas , Doenças dos Roedores , Sifonápteros , Yersinia pestis , Animais , Enterobacteriaceae , Infestações por Pulgas/veterinária , Doenças dos Roedores/microbiologia , Sciuridae/microbiologia , Sifonápteros/microbiologia
15.
Evolution ; 76(5): 946-965, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35398910

RESUMO

Trade-offs are inherent features of many biomechanical systems and are often seen as evolutionary constraints. Structural decoupling may provide a way to escape those limits in some systems but not for structures that transmit large forces, such as mammalian mandibles. For such structures to evolve in multiple directions on a complex adaptive landscape, different regions must change shape while maintaining structural integrity. We evaluated the complexity of the adaptive landscape for mandibular shape in Marmotini, a lineage of ground squirrels that varies in the proportions of seeds and foliage in their diets, by comparing the fit of models based on traits that predict changes in mandibular loading. The adaptive landscape was more complex than predicted by a two-peak model with a single dietary shift. The large number of adaptive peaks reflects a high diversity of directions of shape evolution. The number of adaptive peaks also reflects a multiplicity of functional trade-offs posed by the conflicting demands of processing foods with various combinations of material properties. The ability to balance trade-offs for diets with different proportions of the same foods may account for diversification and disparity of lineages in heterogeneous environments. Rather than constraints, trade-offs may be the impetus of evolutionary change.


Assuntos
Dieta , Mandíbula , Animais , Evolução Biológica , Fenótipo , Sciuridae
16.
Zootaxa ; 5116(3): 301-333, 2022 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-35391332

RESUMO

During a small mammal survey in Wanglang National Natural Reserve, Sichuan, China in AugustOctober 2018, we collected four specimens of an Asiatic striped squirrel (genus Tamiops) that could not be assigned morphologically to any described species. Phylogenetic analyses of CYTB and nuDNA sequences strongly supported them in the genus Tamiops. The p-distances of CYTB between these individuals and other species of Tamiops ranged from 17.4 to 19.1%. Morphologically, they differed from their congeners, including T. maritimus, T. mcclellandii, T. rodolphii, and T. swinhoei by pelage, skull, and baculum characteristics. Based on the results of morphological comparisons and molecular analyses, we describe the four specimens as the new species Tamiops minshanica sp. nov.


Assuntos
Sciuridae , Animais , China , Filogenia , Sciuridae/genética
17.
Am J Physiol Regul Integr Comp Physiol ; 323(1): R28-R42, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35470710

RESUMO

Complexes of the electron transport system can associate with each other to form supercomplexes (SCs) within mitochondrial membranes, perhaps increasing respiratory capacity or reducing reactive oxygen species production. In this study, we determined the abundance, composition, and stability of SCs in a mammalian hibernator, in which both whole animal and mitochondrial metabolism change greatly throughout winter. We isolated mitochondria from thirteen-lined ground squirrels (Ictidomys tridecemlineatus) in different hibernation states, as well as from rats (Rattus norvegicus). We extracted mitochondrial proteins using two nonionic detergents of different strengths and quantified SC abundance using two-dimensional gel electrophoresis and immunoblotting. Rat heart and liver had fewer SCs than ground squirrels. Within ground squirrels, SCs are dynamic, changing among hibernation states within a matter of hours. In brown adipose tissue, Complex III composition in different SCs differed between the torpid and interbout euthermic phase of a hibernation bout. In heart and liver, complex III composition changed between winter and summer. We also evaluated the stability of liver SCs using a stronger detergent and found that the stability of SCs differed; torpor SCs were more stable than the SCs of ground squirrels in other states and rats. This study is the first report of SC changes during hibernation and the first to demonstrate their dynamics on a short timescale.


Assuntos
Hibernação , Torpor , Animais , Transporte de Elétrons , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Hibernação/fisiologia , Ratos , Sciuridae/fisiologia , Torpor/fisiologia
18.
Acta Parasitol ; 67(2): 1035-1038, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35380403

RESUMO

PURPOSE: There is scant information on the coccidia of the gray-collared chipmunk (Neotamias cinereicollis). In this work, two species of Eimeria (Apicomplexa: Eimeriidae) infecting gray-collared chipmunks were identified. METHODS: Twenty-seven gray-collared chipmunks were captured and released at Pivot Rock Canyon, Arizona, USA and their feces were examined for coccidia. Sporulated oöcysts were measured and photographed using differential interference contrast microscopy. RESULTS: The oöcysts of two Eimeria species were identified: E. callospermophili Henry, 1932, and E. vilasi Dorney, 1962. CONCLUSION: This is the first report of E. vilasi and E. callospermophili in gray-collared chipmunks and the first time the latter coccidian has been reported from any species of chipmunk.


Assuntos
Coccidiose , Eimeria , Animais , Arizona , Coccidiose/veterinária , Fezes , Oocistos , Sciuridae
19.
Physiol Biochem Zool ; 95(3): 229-238, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35443147

RESUMO

AbstractDuring hibernation, especially during arousal from torpor to interbout euthermia (IBE), blood flow changes drastically. In nonhibernating mammals, similar changes during ischemia/reperfusion lead to oxidative damage. We hypothesized that suppression of mitochondrial metabolism during hibernation protects against such damage. We compared markers of oxidative damage and total antioxidant capacity in eight tissues among summer, torpid, and IBE thirteen-lined ground squirrels. Overall, summer tissue had less lipid and protein oxidative damage than tissue from the hibernation season, but DNA damage (in four tissues) and total antioxidant capacity (in all eight tissues) were similar among all groups. During torpor, when mitochondrial metabolism is suppressed, lipid damage in heart, brown adipose tissue, and small intestine was lower than IBE by as much as fivefold. By contrast, oxidative damage to protein was at least twofold higher in liver and skeletal muscle in torpor compared with IBE. Our findings suggest that arousal from torpor creates oxidative damage similar to ischemia/reperfusion injury but that this damage is repaired during IBE. These differences cannot be explained by changes in antioxidant capacity, so they are likely due to differences is reactive oxygen species production among hibernation states that may relate to the well-characterized reversible suppression of mitochondrial metabolism during torpor.


Assuntos
Hibernação , Torpor , Animais , Antioxidantes/metabolismo , Nível de Alerta/fisiologia , Hibernação/fisiologia , Lipídeos , Estresse Oxidativo , Sciuridae/fisiologia , Torpor/fisiologia
20.
Curr Biol ; 32(8): 1822-1828.e4, 2022 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-35245461

RESUMO

Adequate nutrition is essential for normal reproductive function, which is vital for species to survive. In humans and other mammals, starvation and undernutrition deplete fat reserves and cause weight loss, attenuating the function of the reproductive axis and causing hypogonadism.1-4 Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) spend 7 months of every year in hibernation without food and water. Hibernating squirrels alternate between periods of torpor and interbout arousal (IBA), when animals temporarily return to an active-like state.5 The physiological significance of IBA is unclear, but it is thought to be essential for hibernation in animals that drop their body temperature to 2°C-4°C during torpor. Here, we report that juvenile male ground squirrels initiate reproductive maturation during their first hibernation season, despite prolonged undernutrition and profound weight loss. We show that the hypothalamic reproductive axis undergoes activation during interbout arousals in the middle of hibernation, triggering production of luteinizing hormone and testosterone, and promoting testicular growth. Initiation of sexual maturation is circannually entrained and is independent of physiological state, ambient temperature, and food availability. Our study suggests a role for interbout arousals during hibernation and uncovers the neurophysiological mechanism of reproductive axis activation during conditions of extreme negative energy balance. VIDEO ABSTRACT.


Assuntos
Hibernação , Desnutrição , Animais , Hibernação/fisiologia , Masculino , Sciuridae/fisiologia , Maturidade Sexual , Perda de Peso
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