scholarly journals Evolved changes in maternal care in high-altitude native deer mice

2021 ◽  
Vol 224 (7) ◽  
Author(s):  
Cayleih E. Robertson ◽  
Grant B. McClelland
Keyword(s):  
High Altitude ◽  
Aerobic Capacity ◽  
Milk Fat ◽  
Sole Source ◽  
Deer Mice ◽  
Low Oxygen ◽  
Nursing Time ◽  
Maximum Aerobic Capacity ◽  
Breeding Seasons ◽  
Limited Scope

ABSTRACT 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.

Meal size and thermic response to food in male subjects as a function of maximum aerobic capacity

Metabolism ◽  
1984 ◽  
Vol 33 (8) ◽  
pp. 743-749 ◽  
Author(s):  
James O. Hill ◽  
Steven B. Heymsfield ◽  
Cliff McMannus ◽  
Mario DiGirolamo
Keyword(s):  
Aerobic Capacity ◽  
Meal Size ◽  
Maximum Aerobic Capacity ◽  
Male Subjects

scholarly journals Oxygen regulation of macrophage migration inhibitory factor in human placenta

2007 ◽  
Vol 292 (1) ◽  
pp. E272-E280 ◽  
Author(s):  
Francesca Ietta ◽  
Yuanhong Wu ◽  
Roberta Romagnoli ◽  
Nima Soleymanlou ◽  
Barbara Orsini ◽  
...  
Keyword(s):  
High Altitude ◽  
Migration Inhibitory Factor ◽  
Macrophage Migration Inhibitory Factor ◽  
Inhibitory Factor ◽  
Extravillous Trophoblast ◽  
Macrophage Migration ◽  
Low Oxygen ◽  
Placental Development

Macrophage migration inhibitory factor (MIF) is an important proinflammatory cytokine involved in regulation of macrophage function. In addition, MIF may also play a role in murine and human reproduction. Although both first trimester trophoblast and decidua express MIF, the regulation and functional significance of this cytokine during human placental development remains unclear. We assessed MIF expression throughout normal human placental development, as well as in in vitro (chorionic villous explants) and in vivo (high altitude placentae) models of human placental hypoxia. Dimethyloxalylglycine (DMOG), which stabilizes hypoxia inducible factor-1 under normoxic conditions, was also used to mimic the effects of hypoxia on MIF expression. Quantitative real-time PCR and Western blot analysis showed high MIF protein and mRNA expression at 7–10 wk and lower levels at 11–12 wk until term. Exposure of villous explants to 3% O2 resulted in increased MIF expression and secretion relative to standard conditions (20% O2). DMOG treatment under 20% O2 increased MIF expression. In situ hybridization and immunohistochemistry showed elevated MIF expression in low oxygen-induced extravillous trophoblast cells. Finally, a significant increase in MIF transcript was observed in placental tissues from high-altitude pregnancies. Hence, three experimental models of placental hypoxia (early gestation, DMOG treatment, and high altitude) converge in stimulating increased MIF, supporting the conclusion that placental-derived MIF is an oxygen-responsive cytokine highly expressed in physiological in vivo and in in vitro low oxygen conditions.

scholarly journals FUNCTIONAL GENOMICS OF ADAPTATION TO HYPOXIC COLD-STRESS IN HIGH-ALTITUDE DEER MICE: TRANSCRIPTOMIC PLASTICITY AND THERMOGENIC PERFORMANCE

Evolution ◽  
2013 ◽  
Vol 68 (1) ◽  
pp. 48-62 ◽  
Author(s):  
Zachary A. Cheviron ◽  
Alex D. Connaty ◽  
Grant B. McClelland ◽  
Jay F. Storz
Keyword(s):  
Cold Stress ◽  
Functional Genomics ◽  
High Altitude ◽  
Deer Mice

The ecology of the deer mouse Peromyscus maniculatus in a coastal coniferous forest. II. Reproduction

1974 ◽  
Vol 52 (1) ◽  
pp. 119-131 ◽  
Author(s):  
R. M. F. S. Sadleir
Keyword(s):  
Deer Mouse ◽  
Coniferous Forest ◽  
Deer Mice ◽  
Reproductive Phenology ◽  
Corpora Lutea ◽  
Temperature Changes ◽  
Four Seasons ◽  
Different Types ◽  
Breeding Condition ◽  
Breeding Seasons

The duration and intensity of reproduction in deer mice was followed for four seasons by live and dead trapping. Three populations living in different types of forest habitat had synchronous breeding seasons, although there were major differences between years in the time of onset and cessation of breeding and in the proportion of females in breeding condition. No consistent relationships were found between either density changes or the incidence of parasitism and reproductive phenology. In the absence of overt food fluctuations there was a relationship between unseasonable temperature changes and breeding. Sudden increases in temperature may have stimulated the onset of breeding but its cessation before the autumn equinox was always associated with a considerable decrease in temperature if this occurred after April. In 57 pregnancies the corpora lutea count was 4.75 ± 1.12 and embryo count was 4.52 ± 1.16. [Formula: see text].

Low P50 in deer mice native to high altitude

1985 ◽  
Vol 58 (1) ◽  
pp. 193-199 ◽  
Author(s):  
L. R. Snyder
Keyword(s):  
High Altitude ◽  
Significant Negative Correlation ◽  
Deer Mice ◽  
Hypoxic Stress ◽  
Hemoglobin Saturation ◽  
Partial Pressures ◽  
Theoretical Predictions ◽  
Low Altitude ◽  
The Difference

Whereas it is widely believed that animals native to high altitude show lower O2 partial pressures at 50% hemoglobin saturation (P50) than do related animals native to low altitude, that “fact” has not been well documented. Consequently, P50 at pH 7.4, PCO2(7.4), the CO2 Bohr effect, and the buffer slope (delta log PCO2/delta pH) were determined via the mixing technique in Peromyscus maniculatus native to a range of altitudes but acclimated to 340 or 3,800 m. PCO2(7.4) and buffer slope were substantially lower at high altitude. The change in P50(7.4) between acclimation altitudes was minimal (0.8% increase at 3,800 m), because of counterbalancing changes in PCO2, 2,3-diphospho-D-glycerate concentration, and perhaps other factors. At both acclimation altitudes there was a highly significant negative correlation between P50(7.4) and native altitude. Since pH in vivo probably increases slightly at high altitude, the data on P50 corrected to pH 7.4 are probably underestimates of the difference in in vivo P50 at low vs. high altitude. Hence these results corroborate theoretical predictions that low P50 is advantageous under severe hypoxic stress.

scholarly journals The Expression Regulatory Network in the Lung Tissue of Tibetan Pigs Provides Insight Into Hypoxia-Sensitive Pathways in High-Altitude Hypoxia

2021 ◽  
Vol 12 ◽  
Author(s):  
Yanan Yang ◽  
Haonan Yuan ◽  
Tianliang Yang ◽  
Yongqing Li ◽  
Caixia Gao ◽  
...  
Keyword(s):  
High Altitude ◽  
Regulatory Networks ◽  
Alveolar Wall ◽  
Potential Candidate ◽  
Low Oxygen ◽  
Structure Damage ◽  
High Altitude Adaptation ◽  
Tibetan Pigs ◽  
Altitude Adaptation ◽  
Insight Into

To adapt to a low-oxygen environment, Tibetan pigs have developed a series of unique characteristics and can transport oxygen more effectively; however, the regulation of the associated processes in high-altitude animals remains elusive. We performed mRNA-seq and miRNA-seq, and we constructed coexpression regulatory networks of the lung tissues of Tibetan and Landrace pigs. HBB, AGT, COL1A2, and EPHX1 were identified as major regulators of hypoxia-induced genes that regulate blood pressure and circulation, and they were enriched in pathways related to signal transduction and angiogenesis, such as HIF-1, PI3K-Akt, mTOR, and AMPK. HBB may promote the combination of hemoglobin and oxygen as well as angiogenesis for high-altitude adaptation in Tibetan pigs. The expression of MMP2 showed a similar tendency of alveolar septum thickness among the four groups. These results indicated that MMP2 activity may lead to widening of the alveolar wall and septum, alveolar structure damage, and collapse of alveolar space with remarkable fibrosis. These findings provide a perspective on hypoxia-adaptive genes in the lungs in addition to insights into potential candidate genes in Tibetan pigs for further research in the field of high-altitude adaptation.

scholarly journals Plasticity of non-shivering thermogenesis and brown adipose tissue in high-altitude deer mice

2021 ◽  
Author(s):  
Soren Z. Coulson ◽  
Cayleih E. Robertson ◽  
Sajeni Mahalingam ◽  
Grant B. McClelland
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
High Altitude ◽  
Heat Production ◽  
Mitochondrial Function ◽  
Mitochondrial Respiration ◽  
Deer Mice ◽  
Brown Adipose ◽  
Hypoxia Acclimation ◽  
Shivering Thermogenesis

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 (P. 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.

scholarly journals Genetic variation in haemoglobin alters breathing in high-altitude deer mice

2021 ◽  
Author(s):  
Catherine M. Ivy ◽  
Oliver H. Wearing ◽  
Chandrasekhar Natarajan ◽  
Rena M. Schweizer ◽  
Natalia Gutiérrez-Pinto ◽  
...  
Keyword(s):  
Genetic Variation ◽  
High Altitude ◽  
Globin Gene ◽  
Respiratory Physiology ◽  
Deer Mice ◽  
Emergent Properties ◽  
Mixed Genetic Background ◽  
Hypoxia Adaptation ◽  
Globin Gene Expression

ABSTRACTPhysiological systems often have emergent properties but the effects of genetic variation on physiology are often unknown, which presents a major challenge to understanding the mechanisms of phenotypic evolution. We investigated the in vivo effects on respiratory physiology of genetic variants in haemoglobin (Hb) that contribute to hypoxia adaptation in high-altitude deer mice (Peromyscus maniculatus). We created F2 inter-population hybrids of highland and lowland deer mice to test the phenotypic effects of α- and β-globin variants on a mixed genetic background. High-altitude genotypes were associated with breathing phenotypes that enhance O2 uptake in hypoxia, including a deeper more effective breathing pattern and an augmented hypoxic ventilatory response. These effects could not be explained by erythrocyte Hb-O2 affinity or globin gene expression in the brainstem. Therefore, adaptive variation in haemoglobin can have unexpected effects on physiology that are distinct from the canonical function of this protein in circulatory O2 transport.

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