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1.
J Exp Biol ; 224(18)2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34495305

RESUMO

Metabolism is a complex phenotype shaped by natural environmental rhythms, as well as behavioral, morphological and physiological adaptations. Metabolism has been historically studied under constant environmental conditions, but new methods of continuous metabolic phenotyping now offer a window into organismal responses to dynamic environments, and enable identification of abiotic controls and the timing of physiological responses relative to environmental change. We used indirect calorimetry to characterize metabolic phenotypes of the desert-adapted cactus mouse (Peromyscus eremicus) in response to variable environmental conditions that mimic their native environment versus those recorded under constant warm and constant cool conditions, with a constant photoperiod and full access to resources. We found significant sexual dimorphism, with males being more prone to dehydration than females. Under circadian environmental variation, most metabolic shifts occurred prior to physical environmental change and the timing was disrupted under both constant treatments. The ratio of CO2 produced to O2 consumed (the respiratory quotient) reached greater than 1.0 only during the light phase under diurnally variable conditions, a pattern that strongly suggests that lipogenesis contributes to the production of energy and endogenous water. Our results are consistent with historical descriptions of circadian torpor in this species (torpid by day, active by night), but reject the hypothesis that torpor is initiated by food restriction or negative water balance.


Assuntos
Adaptação Fisiológica , Torpor , Animais , Ritmo Circadiano , Feminino , Masculino , Camundongos , Peromyscus , Fotoperíodo , Equilíbrio Hidroeletrolítico
2.
Cells ; 10(9)2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34571928

RESUMO

Mammals exhibit a tremendous amount of variation in sperm morphology and despite the acknowledgement of sperm structural diversity across taxa, its functional significance remains poorly understood. Of particular interest is the sperm of rodents. While most Eutherian mammal spermatozoa are relatively simple cells with round or paddle-shaped heads, rodent sperm are often more complex and, in many species, display a striking apical hook. The function of the sperm hook remains largely unknown, but it has been hypothesized to have evolved as an adaptation to inter-male sperm competition and thus has been implicated in increased swimming efficiency or in the formation of collective sperm movements. Here we empirically test these hypotheses within a single lineage of Peromyscus rodents, in which closely related species naturally vary in their mating systems, sperm head shapes, and propensity to form sperm aggregates of varying sizes. We performed sperm morphological analyses as well as in vitro analyses of sperm aggregation and motility to examine whether the sperm hook (i) morphologically varies across these species and (ii) associates with sperm competition, aggregation, or motility. We demonstrate inter-specific variation in the sperm hook and then show that hook width negatively associates with sperm aggregation and sperm swimming speed, signifying that larger hooks may be a hindrance to sperm movement within this group of mice. Finally, we confirmed that the sperm hook hinders motility within a subset of Peromyscus leucopus mice that spontaneously produced sperm with no or highly abnormal hooks. Taken together, our findings suggest that any adaptive value of the sperm hook is likely associated with a function other than inter-male sperm competition, such as interaction with ova or cumulous cells during fertilization, or migration through the complex female reproductive tract.


Assuntos
Evolução Biológica , Peromyscus/fisiologia , Cabeça do Espermatozoide/fisiologia , Motilidade Espermática/fisiologia , Espermatozoides/química , Espermatozoides/fisiologia , Animais , Masculino , Camundongos , Peromyscus/anatomia & histologia
3.
BMC Genomics ; 22(1): 662, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34521341

RESUMO

BACKGROUND: Deer mice (genus Peromyscus) are the most common rodents in North America. Despite the availability of reference genomes for some species, a comprehensive database of polymorphisms, especially in those maintained as living stocks and distributed to academic investigators, is missing. In the present study we surveyed two populations of P. maniculatus that are maintained at the Peromyscus Genetic Stock Center (PGSC) for polymorphisms across their 2.5 × 109 bp genome. RESULTS: High density of variation was identified, corresponding to one SNP every 55 bp for the high altitude stock (SM2) or 207 bp for the low altitude stock (BW) using snpEff (v4.3). Indels were detected every 1157 bp for BW or 311 bp for SM2. The average Watterson estimator for the BW and SM2 populations is 248813.70388 and 869071.7671 respectively. Some differences in the distribution of missense, nonsense and silent mutations were identified between the stocks, as well as polymorphisms in genes associated with inflammation (NFATC2), hypoxia (HIF1a) and cholesterol metabolism (INSIG1) and may possess value in modeling pathology. CONCLUSIONS: This genomic resource, in combination with the availability of P. maniculatus from the PGSC, is expected to promote genetic and genomic studies with this animal model.


Assuntos
Altitude , Peromyscus , Animais , Genômica , Modelos Animais , Peromyscus/genética , Polimorfismo Genético
4.
J Exp Biol ; 224(7)2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-34424979

RESUMO

At high altitude (HA), unremitting low oxygen and persistent cold push small mammals close to their metabolic ceilings, leaving limited scope for aerobically demanding activities. However, HA breeding seasons are relatively short and endemic rodents compensate with larger litters than low altitude (LA) conspecifics. Rodent mothers are the sole source of heat and nutrition for altricial offspring and lactation is energetically costly. Thus, it is unclear how HA females balance energy allocation during the nursing period. We hypothesized that HA female rodents invest heavily in each litter to ensure postnatal survival. We measured maternal energetic output and behaviour in nursing deer mice (Peromyscus maniculatus) native to LA (400 m a.s.l.) and HA (4350 m a.s.l.) under control (24°C, 760 mmHg) and cold hypoxia conditions, simulating HA (5°C, 430 mmHg). Strikingly, resting metabolic rates of lactating HA and LA females under cold hypoxia were 70-85% of their maximum aerobic capacity. In cold hypoxia, LA mothers increased both nursing time and milk fat content, however their pups were leaner and severely growth restricted at weaning. HA mothers also increased nursing in cold hypoxia but for far less time than LA mothers. Despite receiving less care, HA pups in cold hypoxia only experienced small growth restrictions at weaning and maintained body composition. As adults, HA mice raised in cold hypoxia had increased aerobic capacity compared to controls. These data suggest that HA mothers prioritize their own maintenance costs over investing heavily in their offspring. Pups compensate for this lack of care, likely by reducing their own metabolic costs during development.


Assuntos
Altitude , Peromyscus , Animais , Feminino , Hipóxia , Lactação , Camundongos , Oxigênio
5.
Physiol Biochem Zool ; 94(5): 338-352, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34343458

RESUMO

AbstractBasal metabolic rate (BMR) represents the lowest level of aerobic metabolism in a resting, postabsorptive endotherm as measured within the thermoneutral zone. By contrast, maximal metabolic rate ([Formula: see text]max) reflects the upper limit of aerobic metabolism achieved during intensive exercise. As BMR and [Formula: see text]max define the boundaries of the possible levels of aerobic metabolism expressed by a normothermic individual, a key question is whether BMR and [Formula: see text]max are correlated. In the present study, we took repeated paired measurements of thermoneutral resting metabolic rate (RMRt) and [Formula: see text]max on 165 white-footed mice (Peromyscus leucopus). Over a single summer (May-October), repeatability (R ± SE) was low but statistically significant ([Formula: see text]) for both RMRt and [Formula: see text]max ([Formula: see text] for RMRt; [Formula: see text] for [Formula: see text]max). Willingness to run during the forced-exercise trials was also significantly repeatable ([Formula: see text]). At the residual level (within individual), RMRt and [Formula: see text]max tended to be positively correlated ([Formula: see text], [Formula: see text]), suggesting the presence of correlated phenotypic plasticity. By contrast, RMRt and [Formula: see text]max were significantly negatively correlated at the among-individual level ([Formula: see text]). To the extent that variation in RMRt reflects variation in BMR, the negative among-individual correlation does not corroborate the idea that a costly metabolic machinery is needed to support a high [Formula: see text]max. Future research should investigate the (genetic) relationship between RMRt (and BMR) and other energetically expensive behaviors and activities to better understand how energy is allocated within individuals.


Assuntos
Condicionamento Físico Animal , Adaptação Fisiológica , Animais , Metabolismo Basal , Camundongos , Consumo de Oxigênio , Peromyscus , Descanso
6.
PLoS One ; 16(8): e0255295, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34383820

RESUMO

Pair-bonding allows for division of labor across behavioral tasks such as protecting a territory, caring for pups or foraging for food. However, how these labor divisions are determined, whether they are simply intrinsic differences in the individual's behavior or a coordinated behavioral response by the pair, remains unknown. We used the monogamous, biparental and territorial California mouse (Peromyscus californicus) to study how behavioral approach to an aggressive vocal stimulus in a novel environment was affected by pair-bonding. Using a three-chambered vocal playback paradigm, we first measured the amount of time individuals spent in close proximity to aggressive bark vocalizations. We found that animals could be categorized as either approachers or avoiders. We then paired individuals based on their initial approach behavior to an opposite sex individual who displayed either similar or different approach behaviors. These pairs were then retested for approach behavior as a dyad 10-11 days post-pairing. This test found that pairs showed convergence in their behavioral responses, such that pairs who were mismatched in their approach behaviors became more similar, and pairs that were matched remained so. Finally, we analyzed the ultrasonic vocalizations (USV) produced and found that pairs produced significantly more USVs than individuals. Importantly, increased USV production correlated with increasing behavioral convergence of pairs. Taken together, this study shows that pair-bonded animals alter their approach behaviors to coordinate their response with their partner and that vocal communication may play a role in coordinating these behavioral responses. Overall, our findings indicate that pair-bonding generates an emergent property in pairs, adjusting their combined approach behavior towards a new aggressive stimulus representing a potential challenge to the bonded pair. Such findings may be broadly important for social bonding in other social systems.


Assuntos
Peromyscus , Agressão , Animais , Ligação do Par , Comportamento Social , Vocalização Animal
7.
Lab Anim (NY) ; 50(7): 167, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34188230
8.
Artigo em Inglês | MEDLINE | ID: mdl-34119652

RESUMO

Aerobic capacity is a complex performance trait with important consequences for fitness, and is determined by the integrated function of the O2 transport pathway. The components of the O2 pathway interact and function as an integrated physiological system, which could strongly influence the contribution of each component to variation in aerobic capacity. In this commentary, we highlight the value of hierarchical reductionism - combining studies of how component parts work in isolation with studies of how components interact within integrated systems - for understanding the evolution of aerobic capacity. This is achieved by focussing on the role of haemoglobin in adaptive increases in aerobic capacity in high-altitude deer mice (Peromyscus maniculatus). High-altitude deer mice have evolved increased aerobic capacity in hypoxia, in association with evolved changes in several subordinate traits across the O2 pathway. This includes an evolved increase in Hb-O2 affinity - which helps safeguard arterial O2 saturation in hypoxia - and reductionist approaches have been successful at identifying the genetic, structural, and biochemical underpinnings of variation in this trait. However, theoretical modelling and empirical measurements suggest that increased Hb-O2 affinity may not augment aerobic capacity on its own. The adaptive benefit of increased Hb-O2 affinity in high-altitude deer mice appears to have been contingent upon antecedent changes in other traits in the O2 pathway, particularly an increased capacity for O2 diffusion and utilization in active tissues. These findings highlight the importance of understanding the interactions between the components of integrated systems for fully appreciating the evolution of complex performance phenotypes.


Assuntos
Adaptação Fisiológica , Altitude , Hipóxia/fisiopatologia , Oxigênio/metabolismo , Peromyscus/fisiologia , Respiração , Animais
9.
Nat Commun ; 12(1): 3612, 2021 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-34127676

RESUMO

Widespread circulation of SARS-CoV-2 in humans raises the theoretical risk of reverse zoonosis events with wildlife, reintroductions of SARS-CoV-2 into permissive nondomesticated animals. Here we report that North American deer mice (Peromyscus maniculatus) are susceptible to SARS-CoV-2 infection following intranasal exposure to a human isolate, resulting in viral replication in the upper and lower respiratory tract with little or no signs of disease. Further, shed infectious virus is detectable in nasal washes, oropharyngeal and rectal swabs, and viral RNA is detectable in feces and occasionally urine. We further show that deer mice are capable of transmitting SARS-CoV-2 to naïve deer mice through direct contact. The extent to which these observations may translate to wild deer mouse populations remains unclear, and the risk of reverse zoonosis and/or the potential for the establishment of Peromyscus rodents as a North American reservoir for SARS-CoV-2 remains unknown.


Assuntos
COVID-19/veterinária , Peromyscus/virologia , Zoonoses/transmissão , Animais , Animais Selvagens , Anticorpos Neutralizantes/imunologia , COVID-19/patologia , COVID-19/transmissão , Suscetibilidade a Doenças , Fezes/virologia , Feminino , Histiócitos/patologia , Humanos , Masculino , Neutrófilos/imunologia , Neutrófilos/patologia , RNA Viral/isolamento & purificação , SARS-CoV-2/classificação , SARS-CoV-2/genética , Estados Unidos , Zoonoses/virologia
10.
J Exp Biol ; 224(10)2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-34060604

RESUMO

High altitude environments challenge small mammals with persistent low ambient temperatures that require high rates of aerobic heat production in face of low O2 availability. An important component of thermogenic capacity in rodents is non-shivering thermogenesis (NST) mediated by uncoupled mitochondrial respiration in brown adipose tissue (BAT). NST is plastic, and capacity for heat production increases with cold acclimation. However, in lowland native rodents, hypoxia inhibits NST in BAT. We hypothesize that highland deer mice (Peromyscus maniculatus) overcome the hypoxic inhibition of NST through changes in BAT mitochondrial function. We tested this hypothesis using lab born and raised highland and lowland deer mice, and a lowland congeneric (Peromyscus leucopus), acclimated to either warm normoxia (25°C, 760 mmHg) or cold hypoxia (5°C, 430 mmHg). We determined the effects of acclimation and ancestry on whole-animal rates of NST, the mass of interscapular BAT (iBAT), and uncoupling protein (UCP)-1 protein expression. To identify changes in mitochondrial function, we conducted high-resolution respirometry on isolated iBAT mitochondria using substrates and inhibitors targeted to UCP-1. We found that rates of NST increased with cold hypoxia acclimation but only in highland deer mice. There was no effect of cold hypoxia acclimation on iBAT mass in any group, but highland deer mice showed increases in UCP-1 expression and UCP-1-stimulated mitochondrial respiration in response to these stressors. Our results suggest that highland deer mice have evolved to increase the capacity for NST in response to chronic cold hypoxia, driven in part by changes in iBAT mitochondrial function.


Assuntos
Tecido Adiposo Marrom , Peromyscus , Aclimatação , Altitude , Animais , Temperatura Baixa , Tremor por Sensação de Frio , Termogênese
11.
Elife ; 102021 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-33960931

RESUMO

Epidemiological evidence suggests that social interactions and especially bonding between couples influence tumorigenesis, yet whether this is due to lifestyle changes, homogamy (likelihood of individuals to marry people of similar health), or directly associated with host-induced effects in tumors remains debatable. In the present study, we explored if tumorigenesis is associated with the bonding experience in monogamous rodents at which disruption of pair bonds is linked to anxiety and stress. Comparison of lung cancer cell spheroids that formed in the presence of sera from bonded and bond-disrupted deer mice showed that in monogamous Peromyscus polionotus and Peromyscus californicus, but not in polygamous Peromyscus maniculatus, the disruption of pair bonds altered the size and morphology of spheroids in a manner that is consistent with the acquisition of increased oncogenic potential. In vivo, consecutive transplantation of human lung cancer cells between P. californicus, differing in bonding experiences (n = 9 for bonded and n = 7 for bond-disrupted), and nude mice showed that bonding suppressed tumorigenicity in nude mice (p<0.05), suggesting that the protective effects of pair bonds persisted even after bonding ceased. Unsupervised hierarchical clustering indicated that the transcriptomes of lung cancer cells clustered according to the serum donors' bonding history while differential gene expression analysis pointed to changes in cell adhesion and migration. The results highlight the pro-oncogenic effects of pair-bond disruption, point to the acquisition of expression signatures in cancer cells that are relevant to the bonding experiences of serum donors, and question the ability of conventional mouse models to capture the whole spectrum of the impact of the host in tumorigenesis.


Assuntos
Carcinogênese/metabolismo , Proliferação de Células , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Ligação do Par , Células A549 , Animais , Ansiedade , Adesão Celular , Movimento Celular , Transplante de Células , Feminino , Perfilação da Expressão Gênica , Humanos , Neoplasias Pulmonares/psicologia , Masculino , Camundongos Nus , Transplante de Neoplasias , Peromyscus , Esferoides Celulares , Estresse Psicológico
12.
Behav Processes ; 188: 104415, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33945866

RESUMO

The strictly monogamous California mouse (Peromyscus californicus) forms life-long pair bonds and mates exclusively with a single partner. While studies in the wild indicate that individuals may re-pair with a new partner following mate loss, the preponderance of this behavior and subsequent reproductive outcomes following re-pairing are understudied. To examine reproductive outcomes following re-pairing and to look for sex-specific differences following mate loss, birth records of 584 California mouse pairs from our laboratory were analyzed. Of these pairs, 59 pairs were identified as re-pairs and used for further descriptive analysis. We found that 50/59 (84.7 %) of re-paired animals gave birth, indicating that reproduction with a new mate is not only possible, but perhaps more common than previously described for this species. Additionally, we found that when re-paired, females took significantly longer to birth a subsequent litter as compared to original breeding pairs. Overall findings from the current study provide evidence for sex differences in reproductive outcomes following repairing and for greater flexibility in mating strategy for a species described as strictly monogamous.


Assuntos
Ligação do Par , Roedores , Animais , Feminino , Masculino , Peromyscus , Reprodução , Caracteres Sexuais
13.
PLoS Pathog ; 17(5): e1009585, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34010360

RESUMO

Coronavirus disease-19 (COVID-19) emerged in late 2019 in China and rapidly became pandemic. As with other coronaviruses, a preponderance of evidence suggests the virus originated in horseshoe bats (Rhinolophus spp.) and may have infected an intermediate host prior to spillover into humans. A significant concern is that SARS-CoV-2 could become established in secondary reservoir hosts outside of Asia. To assess this potential, we challenged deer mice (Peromyscus maniculatus) with SARS-CoV-2 and found robust virus replication in the upper respiratory tract, lungs and intestines, with detectable viral RNA for up to 21 days in oral swabs and 6 days in lungs. Virus entry into the brain also occurred, likely via gustatory-olfactory-trigeminal pathway with eventual compromise to the blood-brain barrier. Despite this, no conspicuous signs of disease were observed, and no deer mice succumbed to infection. Expression of several innate immune response genes were elevated in the lungs, including IFNα, IFNß, Cxcl10, Oas2, Tbk1 and Pycard. Elevated CD4 and CD8ß expression in the lungs was concomitant with Tbx21, IFNγ and IL-21 expression, suggesting a type I inflammatory immune response. Contact transmission occurred from infected to naive deer mice through two passages, showing sustained natural transmission and localization into the olfactory bulb, recapitulating human neuropathology. In the second deer mouse passage, an insertion of 4 amino acids occurred to fixation in the N-terminal domain of the spike protein that is predicted to form a solvent-accessible loop. Subsequent examination of the source virus from BEI Resources determined the mutation was present at very low levels, demonstrating potent purifying selection for the insert during in vivo passage. Collectively, this work has determined that deer mice are a suitable animal model for the study of SARS-CoV-2 respiratory disease and neuropathogenesis, and that they have the potential to serve as secondary reservoir hosts in North America.


Assuntos
COVID-19/fisiopatologia , COVID-19/transmissão , Peromyscus/virologia , Doenças dos Roedores/transmissão , Animais , Encéfalo/patologia , Encéfalo/virologia , COVID-19/patologia , Modelos Animais de Doenças , Reservatórios de Doenças , Suscetibilidade a Doenças , Feminino , Masculino , Doenças dos Roedores/patologia , Doenças dos Roedores/virologia , Glicoproteína da Espícula de Coronavírus/genética , Replicação Viral
14.
mBio ; 12(2)2021 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-33849979

RESUMO

Animals that are competent reservoirs of zoonotic pathogens commonly suffer little morbidity from the infections. To investigate mechanisms of this tolerance of infection, we used single-dose lipopolysaccharide (LPS) as an experimental model of inflammation and compared the responses of two rodents: Peromyscus leucopus, the white-footed deermouse and reservoir for the agents of Lyme disease and other zoonoses, and the house mouse Mus musculus Four hours after injection with LPS or saline, blood, spleen, and liver samples were collected and subjected to transcriptome sequencing (RNA-seq), metabolomics, and specific reverse transcriptase quantitative PCR (RT-qPCR). Differential expression analysis was at the gene, pathway, and network levels. LPS-treated deermice showed signs of sickness similar to those of exposed mice and had similar increases in corticosterone levels and expression of interleukin 6 (IL-6), tumor necrosis factor, IL-1ß, and C-reactive protein. By network analysis, the M. musculus response to LPS was characterized as cytokine associated, while the P. leucopus response was dominated by neutrophil activity terms. In addition, dichotomies in the expression levels of arginase 1 and nitric oxide synthase 2 and of IL-10 and IL-12 were consistent with type M1 macrophage responses in mice and type M2 responses in deermice. Analysis of metabolites in plasma and RNA in organs revealed species differences in tryptophan metabolism. Two genes in particular signified the different phenotypes of deermice and mice: the Slpi and Ibsp genes. Key RNA-seq findings for P. leucopus were replicated in older animals, in a systemic bacterial infection, and with cultivated fibroblasts. The findings indicate that P. leucopus possesses several adaptive traits to moderate inflammation in its balancing of infection resistance and tolerance.IMPORTANCE Animals that are natural carriers of pathogens that cause human diseases commonly manifest little or no sickness as a consequence of infection. Examples include the deermouse, Peromyscus leucopus, which is a reservoir for Lyme disease and several other disease agents in North America, and some types of bats, which are carriers of viruses with pathogenicity for humans. Mechanisms of this phenomenon of infection tolerance and entailed trade-off costs are poorly understood. Using a single injection of lipopolysaccharide (LPS) endotoxin as a proxy for infection, we found that deermice differed from the mouse (Mus musculus) in responses to LPS in several diverse pathways, including innate immunity, oxidative stress, and metabolism. Features distinguishing the deermice cumulatively would moderate downstream ill effects of LPS. Insights gained from the P. leucopus model in the laboratory have implications for studying infection tolerance in other important reservoir species, including bats and other types of wildlife.


Assuntos
Reservatórios de Doenças/microbiologia , Endotoxinas/administração & dosagem , Inflamação/genética , Peromyscus/microbiologia , Zoonoses/imunologia , Zoonoses/microbiologia , Animais , Suscetibilidade a Doenças/etiologia , Suscetibilidade a Doenças/imunologia , Endotoxinas/imunologia , Feminino , Perfilação da Expressão Gênica , Inflamação/imunologia , Doença de Lyme/microbiologia , Masculino , Metabolômica , Camundongos , Camundongos Endogâmicos BALB C , Peromyscus/imunologia , Análise de Sequência de RNA
15.
Am J Physiol Regul Integr Comp Physiol ; 320(6): R800-R811, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33826424

RESUMO

Hypoxia at high altitude can constrain metabolism and performance and can elicit physiological adjustments that are deleterious to health and fitness. Hypoxic pulmonary hypertension is a particularly serious and maladaptive response to chronic hypoxia, which results from vasoconstriction and pathological remodeling of pulmonary arteries, and can lead to pulmonary edema and right ventricle hypertrophy. We investigated whether deer mice (Peromyscus maniculatus) native to high altitude have attenuated this maladaptive response to chronic hypoxia and whether evolved changes or hypoxia-induced plasticity in pulmonary vasculature might impact ventilation-perfusion (V-Q) matching in chronic hypoxia. Deer mouse populations from both high and low altitudes were born and raised to adulthood in captivity at sea level, and various aspects of lung function were measured before and after exposure to chronic hypoxia (12 kPa O2, simulating the O2 pressure at 4,300 m) for 6-8 wk. In lowlanders, chronic hypoxia increased right ventricle systolic pressure (RVSP) from 14 to 19 mmHg (P = 0.001), in association with thickening of smooth muscle in pulmonary arteries and right ventricle hypertrophy. Chronic hypoxia also impaired V-Q matching in lowlanders (measured at rest using SPECT-CT imaging), as reflected by increased log SD of the perfusion distribution (log SDQ) from 0.55 to 0.86 (P = 0.031). In highlanders, chronic hypoxia had attenuated effects on RVSP and no effects on smooth muscle thickness, right ventricle mass, or V-Q matching. Therefore, evolved changes in lung function help attenuate maladaptive plasticity and contribute to hypoxia tolerance in high-altitude deer mice.


Assuntos
Hipertensão Pulmonar/fisiopatologia , Hipóxia/fisiopatologia , Consumo de Oxigênio/fisiologia , Oxigênio/metabolismo , Peromyscus/metabolismo , Aclimatação/fisiologia , Animais , Hipertensão Pulmonar/metabolismo , Pulmão/fisiopatologia , Camundongos , Perfusão , Peromyscus/fisiologia
16.
BMC Genomics ; 22(1): 291, 2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33882817

RESUMO

BACKGROUND: Genes that belong to the same network are frequently co-expressed, but collectively, how the coordination of the whole transcriptome is perturbed during aging remains unclear. To explore this, we calculated the correlation of each gene in the transcriptome with every other, in the brain of young and older outbred deer mice (P. leucopus and P. maniculatus). RESULTS: In about 25 % of the genes, coordination was inversed during aging. Gene Ontology analysis in both species, for the genes that exhibited inverse transcriptomic coordination during aging pointed to alterations in the perception of smell, a known impairment occurring during aging. In P. leucopus, alterations in genes related to cholesterol metabolism were also identified. Among the genes that exhibited the most pronounced inversion in their coordination profiles during aging was THBS4, that encodes for thrombospondin-4, a protein that was recently identified as rejuvenation factor in mice. Relatively to its breadth, abolishment of coordination was more prominent in the long-living P. leucopus than in P. maniculatus but in the latter, the intensity of de-coordination was higher. CONCLUSIONS: There sults suggest that aging is associated with more stringent retention of expression profiles for some genes and more abrupt changes in others, while more subtle but widespread changes in gene expression appear protective. Our findings shed light in the mode of the transcriptional changes occurring in the brain during aging and suggest that strategies aiming to broader but more modest changes in gene expression may be preferrable to correct aging-associated deregulation in gene expression.


Assuntos
Envelhecimento , Peromyscus , Envelhecimento/genética , Animais , Encéfalo , Metabolismo dos Lipídeos , Camundongos , Peromyscus/genética , Transcriptoma
17.
Integr Comp Biol ; 61(2): 385-397, 2021 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-33871633

RESUMO

Determining how variation in morphology affects animal performance (and ultimately fitness) is key to understanding the complete process of evolutionary adaptation. Long tails have evolved many times in arboreal and semi-arboreal rodents; in deer mice, long tails have evolved repeatedly in populations occupying forested habitat even within a single species (Peromyscus maniculatus). Here, we use a combination of functional modeling, laboratory studies, and museum records to test hypotheses about the function of tail-length variation in deer mice. First, we use computational models, informed by museum records documenting natural variation in tail length, to test whether differences in tail morphology between forest and prairie subspecies can influence performance in behavioral contexts relevant for tail use. We find that the deer- mouse tail plays little role in statically adjusting center of mass or in correcting body pitch and yaw, but rather it can affect body roll during arboreal locomotion. In this context, we find that even intraspecific tail-length variation could result in substantial differences in how much body rotation results from equivalent tail motions (i.e., tail effectiveness), but the relationship between commonly-used metrics of tail-length variation and effectiveness is non-linear. We further test whether caudal vertebra length, number, and shape are associated with differences in how much the tail can bend to curve around narrow substrates (i.e., tail curvature) and find that, as predicted, the shape of the caudal vertebrae is associated with intervertebral bending angle across taxa. However, although forest and prairie mice typically differ in both the length and number of caudal vertebrae, we do not find evidence that this pattern is the result of a functional trade-off related to tail curvature. Together, these results highlight how even simple models can both generate and exclude hypotheses about the functional consequences of trait variation for organismal-level performance.


Assuntos
Evolução Biológica , Peromyscus/anatomia & histologia , Cauda , Animais , Ecossistema , Locomoção , Cauda/anatomia & histologia
18.
Parasitol Int ; 83: 102315, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33677125

RESUMO

Moniliformis ibunami n. sp., is described from the intestine of the transvolcanic deermouse Peromyscus hylocetes Merriam 1898 (Cricetidae) from Parque Nacional Nevado de Colima "El Floripondio", Jalisco, Mexico. The new species can be distinguished morphologically from the other 18 congeneric species of Moniliformis by a combination of morphological and molecular characters including the number of hooks on the proboscis (12 longitudinal rows, each one with six to eight transversally arranged unrooted hooks), the proboscis length (230-270 µm), the female trunk length (159-186 mm) and egg size (40-70 × 20-40). For molecular distinction, nearly complete sequences of the small subunit (SSU) and large subunit (LSU) of the nuclear ribosomal DNA and cytochrome oxidase subunit 1 (cox 1) of the mitochondrial DNA of the new species were obtained and compared with available sequences downloaded from GenBank. Phylogenetic analyses inferred with the three molecular markers consistently showed that Moniliformis ibunami n. sp. is sister to other congeneric species of Moniliformis. The genetic distance with cox 1 gene among Moniliformis ibunami n. sp., M. saudi, M. cryptosaudi, M. kalahariensis, M. necromysi and M. moniliformis ranged from 20 to 27%. Morphological evidence and high genetic distance, plus the phylogenetic analyses, indicate that acanthocephalans collected from the intestines of transvolcanic deer mice represent a new species which constitutes the seventh species of the genus Moniliformis in the Americas.


Assuntos
Helmintíase Animal/epidemiologia , Moniliformis/classificação , Peromyscus , Doenças dos Roedores/epidemiologia , Animais , Feminino , Genes de Helmintos , Helmintíase Animal/parasitologia , Masculino , México/epidemiologia , Microscopia Eletrônica de Varredura , Moniliformis/anatomia & histologia , Moniliformis/genética , Moniliformis/ultraestrutura , Filogenia , Prevalência , Doenças dos Roedores/parasitologia
19.
Am J Physiol Regul Integr Comp Physiol ; 320(5): R735-R746, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33729020

RESUMO

When at their maximum thermogenic capacity (cold-induced V̇o2max), small endotherms reach levels of aerobic metabolism as high, or even higher, than running V̇o2max. How these high rates of thermogenesis are supported by substrate oxidation is currently unclear. The appropriate utilization of metabolic fuels that could sustain thermogenesis over extended periods may be important for survival in cold environments, like high altitude. Previous studies show that high capacities for lipid use in high-altitude deer mice may have evolved in concert with greater thermogenic capacities. The purpose of this study was to determine how lipid utilization at both moderate and maximal thermogenic intensities may differ in high- and low-altitude deer mice, and strictly low-altitude white-footed mice. We also examined the phenotypic plasticity of lipid use after acclimation to cold hypoxia (CH), conditions simulating high altitude. We found that lipids were the primary fuel supporting both moderate and maximal rates of thermogenesis in both species of mice. Lipid oxidation increased threefold in mice from 30°C to 0°C, consistent with increases in oxidation of [13C]palmitic acid. CH acclimation led to an increase in [13C]palmitic acid oxidation at 30°C but did not affect total lipid oxidation. Lipid oxidation rates at cold-induced V̇o2max were two- to fourfold those at 0°C and increased further after CH acclimation, especially in high-altitude deer mice. These are the highest mass-specific lipid oxidation rates observed in any land mammal. Uncovering the mechanisms that allow for these high rates of oxidation will aid our understanding of the regulation of lipid metabolism.


Assuntos
Altitude , Metabolismo dos Lipídeos/fisiologia , Peromyscus/fisiologia , Termogênese/fisiologia , Aclimatação/fisiologia , Adaptação Fisiológica/fisiologia , Animais , Camundongos , Oxirredução , Consumo de Oxigênio/fisiologia
20.
J Comp Physiol B ; 191(3): 589-601, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33644836

RESUMO

Small, non-hibernating endotherms increase their thermogenic capacity to survive seasonal cold, through adult phenotypic flexibility. In mammals, this response is primarily driven by remodeling of brown adipose tissue (BAT), which matures postnatally in altricial species. In many regions, ambient temperatures can vary dramatically throughout the breeding season. We used second-generation lab-born Peromyscus leucopus, cold exposed during two critical developmental windows, to test the hypothesis that adult phenotypic flexibility to cold is influenced by rearing temperature. We found that cold exposure during the postnatal period (14 °C, birth to 30 days) accelerated BAT maturation and permanently remodeled this tissue. As adults, these mice had increased BAT activity and thermogenic capacity relative to controls. However, they also had a blunted acclimation response when subsequently cold exposed as adults (5 °C for 6 weeks). Mice born to cold-exposed mothers (14 °C, entire pregnancy) also showed limited capacity for flexibility as adults, demonstrating that maternal cold stress programs the offspring thermal acclimation response. In contrast, for P. maniculatus adapted to the cold high alpine, BAT maturation rate was unaffected by rearing temperature. However, both postnatal and prenatal cold exposure limited the thermal acclimation response in these cold specialists. Our results suggest a complex interaction between developmental and adult environment, influenced strongly by ancestry, drives thermogenic capacity in the wild.


Assuntos
Tecido Adiposo Marrom , Peromyscus , Aclimatação , Animais , Temperatura Baixa , Camundongos , Termogênese
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