Immigration and seasonal bottlenecks: high inbreeding despite high genetic diversity in an oscillating population of Culicoides sonorensis (Diptera: Ceratopogonidae).

Most population genetic studies concern spatial genetic differentiation, but far fewer aim at analyzing the temporal genetic changes that occur within populations. Vector species, including mosquitoes and biting midges, are often characterized by oscillating adult population densities, which may affect their dispersal, selection, and genetic diversity over time. Here, we used a population of Culicoides sonorensis from a single site in California to investigate short-term (intra-annual) and long-term (inter-annual) temporal variation in genetic diversity over a 3 yr period. This biting midge species is the primary vector of several viruses affecting both wildlife and livestock, thus a better understanding of the population dynamics of this species can help inform epidemiological studies. We found no significant genetic differentiation between months or years, and no correlation between adult populations and the inbreeding coefficient (FIS). However, we show that repeated periods of low adult abundance during cooler winter months resulted in recurring bottleneck events. Interestingly, we also found a high number of private and rare alleles, which suggests both a large, stable population, as well as a constant influx of migrants from nearby populations. Overall, we showed that the high number of migrants maintains a high level of genetic diversity by introducing new alleles, while this increased diversity is counterbalanced by recurrent bottleneck events potentially purging unfit alleles each year. These results highlight the temporal influences on population structure and genetic diversity in C. sonorensis and provide insight into factors effecting genetic variation that may occur in other vector species with fluctuating populations.

Advancing the Study of Mindfulness-Based Interventions in Relation to Psychological Health.

Since 2006, there has been exponential growth in the number of publications on mindfulness [...].

Oral Sampling of Little Brown Bat (Myotis lucifugus) Maternity Colonies for SARS-CoV-2 in the Northeast and Mid-Atlantic, USA.

The potential introduction of SARS-CoV-2, the virus responsible for the COVID-19 pandemic, into North American bat populations is of interest to wildlife managers due to recent disease-mediated declines of several species. Populations of little brown bats (Myotis lucifugus) have collapsed due to white-nose syndrome (WNS), a disease caused by the introduction and spread of the fungal pathogen Pseudogymnoascus destructans (Pd). Throughout much of the United States and southern Canada, large colonies of the species routinely established diurnal roosts in anthropogenic structures, thereby creating the potential for direct human contact and cross-species disease transmission. Given recent declines and the potential for further disease impacts, we collected oral swabs from eight little brown bat maternity colonies to assess the presence and prevalence of SARS-CoV-2 by RT-qPCR analysis. Little brown bat colonies in Maryland (n = 1), New Hampshire (n = 1), New Jersey (n = 2), New York (n = 1), Rhode Island (n = 2), and Virginia (n = 1) were taken during May-August, 2022. From 235 assayed individuals, no bat tested positive for SARS-CoV-2. Our results indicate that little brown bats may not contract SARS-CoV-2 or that the virus persists at undetectable levels in populations of the Mid-Atlantic and Northeast during summer months. Nonetheless, continued monitoring and future work addressing other seasons may still be warranted to conclusively determine infection status.

The impact of modifications in cadaver dissection time on student learning outcomes in a doctor of physical therapy program.

Human anatomy is a foundational component of medical and allied health professional education. Doctor of Physical Therapy (DPT) programs are required to teach anatomy, however the pedagogies used are at the discretion of faculty and institutions. Cadaver dissection may have been the predominant instruction methodology in DPT programs in the past; new technology provides alternative interactive teaching methods. This paper describes the modifications in an anatomy curriculum over 5 years in one DPT program, and the impact on student perception and learning outcomes. This was a retrospective, quantitative study that utilized a survey to collect data on student perceptions about the anatomy pedagogy; the learning outcomes analyzed were grades and licensure exam pass rates. We report on outcomes for five cohorts within one DPT program. IRB approval was obtained for the research. Despite the decrease in cadaver laboratory time after 2016, students' final exam grades in Gross Anatomy improved and the first time pass rate for the national licensure exam increased. Most students rated cadaver laboratory and the active learning assignments that replaced traditional cadaver laboratory time as valuable to their learning; however, there were differences in opinions between cohorts. Although the outcomes might not reflect a direct result of dissection time, the study confirmed that using alternative methods for teaching anatomy did not hinder student performance. Using innovative pedagogy allows educators to achieve student success in spite of decreased gross dissection time.

Associations Between Children's Emotion Regulation, Mindful Parenting, Parent Stress, and Parent Coping During the COVID-19 Pandemic.

Stress among parents has increased during the COVID-19 pandemic. Research prior to the pandemic indicates that parents of children who struggle with emotion regulation (ER) and who themselves are less mindful report more stress and diminished coping abilities. We know little, however, about these associations in the context of COVID-19. To prevent COVID-related deteriorations in parent well-being and child outcomes and to support parents during this potentially challenging time, it is important to understand the factors that are associated with increased stress as well as adaptive coping. This paper discusses the association between children's ER, mindful parenting (MP), parent stress, and parents' coping with parenting during the pandemic in a sample of 217 caregivers of school-aged children (91.0% mothers). Results indicated that children's ER was associated with parents' self-reported coping with parenting in the pandemic but was not associated with increased stress. Further, MP moderated the association between children's ER and coping, such that parents who were the most mindful and had children with better ER skills reported significantly greater ability to cope with pandemic parenting. Coping was lower for other combinations of ER and mindful parenting. These findings contradict those from before COVID, suggesting the relationship between children's ER and parent outcomes may differ in the COVID-19 context, and offering insights into which parents may be most likely to struggle with coping with pandemic parenting.

Mental health and health behaviors among college student mentors in a randomized controlled trial interrupted by COVID-19.

Objective: The benefits of mindfulness-training and mentoring for college students have yet to be investigated. We aimed to provide an exploratory and descriptive account of their potential benefits during the COVID-19 pandemic. Participants: In February 2020, 49 undergraduates (M = 20.51 years-old; 94% female) participated in a randomized trial of 12-week mentoring + mindfulness or mentoring-as-usual. After five weekly mentoring-sessions, programs were interrupted by COVID-19; mentoring continued online. Methods: Undergraduates completed questionnaires about mental health, behaviors, and regulatory processes in February and July 2020, with additional COVID-19-related questions at follow-up. Results: Participants reported moderate COVID-19-related perceived stress, but mental health, health behaviors, and regulatory processes did not diminish over time, with no condition differences. Undergraduates described using contemplative practices and social support to cope with COVID-19-stress. Conclusions: Undergraduates showed stable mental health/health behaviors despite moderate COVID-19-related-stress. Future research on mentoring with a mindfulness component among a larger and more heterogeneous sample will be necessary.

Development of microsatellite markers for population genetics of biting midges and a potential tool for species identification of Culicoides sonorensis Wirth & Jones.

BACKGROUND: Proper vector surveillance relies on the ability to identify species of interest accurately and efficiently, though this can be difficult in groups containing cryptic species. Culicoides Latreille is a genus of small biting flies responsible for the transmission of numerous pathogens to a multitude of vertebrates. Regarding pathogen transmission, the C. variipennis species complex is of particular interest in North America. Of the six species within this group, only C. sonorensis Wirth & Jones is a proven vector of bluetongue virus and epizootic hemorrhagic disease virus. Unfortunately, subtle morphological differences, cryptic species, and mitonuclear discordance make species identification in the C. variipennis complex challenging. Recently, single-nucleotide polymorphism (SNP) analysis enabled discrimination between the species of this group; however, this demanding approach is not practical for vector surveillance. METHODS: The aim of the current study was to develop a reliable and affordable way of distinguishing between the species within the C. variipennis complex, especially C. sonorensis. Twenty-five putative microsatellite markers were identified using the C. sonorensis genome and tested for amplification within five species of the C. variipennis complex. Machine learning was then used to determine which markers best explain the genetic differentiation between species. This led to the development of a subset of four and seven markers, which were also tested for species differentiation. RESULTS: A total of 21 microsatellite markers were successfully amplified in the species tested. Clustering analyses of all of these markers recovered the same species-level identification as the previous SNP data. Additionally, the subset of seven markers was equally capable of accurately distinguishing between the members of the C. variipennis complex as the 21 microsatellite markers. Finally, one microsatellite marker (C508) was found to be species-specific, only amplifying in the vector species C. sonorensis among the samples tested. CONCLUSIONS: These microsatellites provide an affordable way to distinguish between the sibling species of the C. variipennis complex and could lead to a better understanding of the species dynamics within this group. Additionally, after further testing, marker C508 may allow for the identification of C. sonorensis with a single-tube assay, potentially providing a powerful new tool for vector surveillance in North America.

Assessing colony elimination in multicolonial ants: Estimating field efficacy of insecticidal baits against the invasive dark rover ant (Brachymyrmex patagonicus).

BACKGROUND: A frequent goal of pest management strategies targeting social insects is total colony elimination. Insecticidal baits are highly effective at controlling social insect pests, although their ability to provide total colony elimination has only been well studied in a few species. Genetically testing colony elimination in many urban pest ants can be challenging due to indistinct colony boundaries observed in unicolonial, invasive species; however, some pest ants, such as the dark rover ant (Brachymyrmex patagonicus), maintain strict colony borders through aggression towards non-nestmates. Each of these distinct colonies can be identified using molecular markers, allowing for the tracking of individual colonies pre- and post-treatment to measure colony density. While counting the number of foraging workers to assess treatment efficacy may suffice in some cases, it offers little insight into the colony-level impacts of a treatment. RESULTS: Using microsatellite markers, distinct rover ant colonies were identified and tracked around residential structures before and after the application of an imidacloprid bait. The number of foraging ants at the treated structures was reduced by an average of 83.0% over a 28-day observation period. Baiting also significantly reduced the total number of colonies present. At the treatment structures, only ~25% of the original colonies remained at the end of the study. Colonies with foraging trails <1.5 m from a bait station had a higher chance of being eliminated. CONCLUSION: Using insecticidal baits against B. patagonicus can be highly effective at colony elimination; however, with such small foraging ranges and high colony densities, proper placement is required to ensure enough bait is properly positioned to treat all colonies affecting a structure. © 2022 Society of Chemical Industry.

Adherence and Health-Related Outcomes of Beginner Running Programs: A 10-Week Observational Study.

Purpose: This study aimed to explore the determinants of adherence and assess changes in fitness and health outcomes in participants of group-based beginner running programs. Methods: Participants completed adherence diaries (n = 34) during the 10-week program, and underwent fitness and health testing (n = 20) at the program start and end. Diaries included weekly visual analogue scales of enjoyment, motivation, confidence, fatigue, satisfaction, and support along with a record of training sessions. Space was provided for free-text comments. Fitness was assessed by the multi-stage 20-m shuttle run test, and measurements were taken of resting heart rate, blood pressure, body composition, and free-living physical activity. Results: Overall adherence to the 10-week program was 53 ± 27% with injury the most common reason for missing sessions and for discontinuing training. Adherence to group sessions was positively correlated with enjoyment, motivation, confidence, satisfaction with progress, and social support. Qualitative analysis of diary entries indicated three distinct themes (self-awareness, social support, personal challenge) underlying progression through the program. Significant changes were observed after 10 weeks in distance run on the fitness test (+189 ± 133 m), body mass index (-0.54 ± 0.72 kg/m2), and percentage body fat (-1.5 ± 1.6%). Blood pressure, resting heart rate, and physical activity were unchanged. Conclusion: Engagement in beginner running programs was associated with improvements in cardiorespiratory fitness and body composition within 10 weeks. A larger and longer-term study is required to determine if these programs can lead to sustained engagement in running and additional health benefits.

Testing Bidirectional Within-Person Associations between Mindful Attention and Sleep in Adolescence.

Developments during adolescence increase risk for sleep problems. Research in adults suggests mindfulness and sleep are associated, with two different theoretical explanations for direction of effects. Our goal was to directly test these competing theoretical models at the daily level in adolescents using objective and self-reported measurements of sleep. Adolescents (N=138; 14-21yrs) reported mindful attention and sleep for a week, while wearing an actigraph. Results indicated that, within-person, poor sleep at night predicted less mindful attention the next day; however, mindful attention during the day did not predict sleep that night. These findings provide support for the developmental model of sleep and regulation and suggest poor sleep may impair regulatory abilities the following day.

Health effects of COVID-19 for vulnerable adolescents in a randomized controlled trial.

Emerging evidence suggests the coronavirus disease 2019 (COVID-19) pandemic is adversely affecting adolescents' mental health and health behaviors, particularly among those with preexisting mental health conditions and from lower socioeconomic backgrounds. However, direct tests of changes in health outcomes among vulnerable adolescents from before to during COVID-19 are limited. In addition, little is known about how to buffer adolescents, particularly those who are most vulnerable, against stress-related decrements in health. This randomized controlled trial begins to fill these gaps in the literature by exploring changes in mental health, health behaviors, executive function, emotion regulation, and mindfulness among vulnerable adolescents involved in a mentoring program during the COVID-19 pandemic. It also examined to what extent there were protective benefits of incorporating mindfulness training within a mentoring program for buffering adolescents from negative pandemic health effects. Thirty-five adolescents (Mage = 12.9, 37% female) and 32 parents (Mage = 44.75, 80% female) completed questionnaires at baseline (February 2020) and follow-up (July 2020). There were few significant reductions in health; instead, on average, youth reported improvements in sleep, emotion regulation, executive function, and mindfulness over time. Adolescents randomized to mentoring + mindfulness displayed significantly less posttraumatic stress disorder (PTSD) symptomatology and emotional impulsivity at follow-up, compared to the mentoring-as-usual condition. These pilot findings suggest that mentoring with a mindfulness training component may offer an effective strategy for protecting adolescents from deteriorations in health outcomes during COVID-19. Further, there may be unique benefits of mindfulness training for vulnerable youth as a way to adapt to stressful events. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Development of a Set of Microsatellite Markers to Investigate Sexually Antagonistic Selection in the Invasive Ant Nylanderia fulva.

Sexually antagonistic selection (SAS) occurs when distinct alleles are differentially selected in each sex. In the invasive tawny crazy ant, Nylanderia fulva, a genomic region is under SAS, while the rest of the genome is randomly selected in males and females. In this study, we designed a suite of 15 microsatellite markers to study the origin and evolution of SAS in N. fulva. These SAS markers were polymorphic, with allelic frequencies that are highly different between males and females. All haploid males carry only a subset of the alleles present in the population, while females are reliably heterozygous, with one allele from the male gene pool and a different allele inherited from their mother. In addition, we identified six polymorphic markers not associated with SAS and six markers yielding consistent, yet monomorphic, amplification in the introduced range of this species. Reaction condition optimizations allowed all retained markers to be co-amplified in four PCR mixes. The SAS markers may be used to test for the strength and the extent of the genomic regions under SAS in both the native and introduced ranges of N. fulva, while the set of non-SAS loci may be used to assess the invasion route of this species. Overall, the application of these microsatellite markers will yield insights into the origin and evolution of SAS within and among species of the genus Nylanderia.

Divide and conquer: Multicolonial structure, nestmate recognition, and antagonistic behaviors in dense populations of the invasive ant Brachymyrmex patagonicus.

The ecological success of ants has made them abundant in most environments, yet inter- and intraspecific competition usually limit nest density for a given population. Most invasive ant populations circumvent this limitation through a supercolonial structure, eliminating intraspecific competition through a loss of nestmate recognition and lack of aggression toward non-nestmates. Native to South America, Brachymyrmex patagonicus has recently invaded many locations worldwide, with invasive populations described as extremely large and dense. Yet, in contrast with most invasive ants, this species exhibits a multicolonial structure, whereby each colony occupies a single nest. Here, we investigated the interplay between genetic diversity, chemical recognition, and aggressive behaviors in an invasive population of B. patagonicus. We found that, in its invasive range, this species reaches a high nest density with individual colonies located every 2.5 m and that colony boundaries are maintained through aggression toward non-nestmates. This recognition and antagonism toward non-nestmates is mediated by chemical differentiation between colonies, as different colonies exhibit distinct chemical profiles. We highlighted that the level of aggression between colonies is correlated with their degree of genetic difference, but not their overall chemical differentiation. This may suggest that only a few chemical compounds influence nestmate recognition in this species or that weak chemical differences are sufficient to elicit aggression. Overall, this study demonstrates that invasive ant populations can reach high densities despite a multicolonial structure with strong aggression between colonies, raising questions about the factors underlying their ecological success and mitigating negative consequences of competitive interactions.

HIP AND PELVIC STABILITY AND GAIT RETRAINING IN THE MANAGEMENT OF ATHLETIC PUBALGIA AND HIP LABRAL PATHOLOGY IN A FEMALE RUNNER: A CASE REPORT.

BACKGROUND: Athletic pubalgia is a prevalent injury in athletes who kick, pivot, and cut, however it is poorly described in the literature. Many athletes with this diagnosis fail conservative management secondary to continued pain with activity and require surgical intervention for return to sport. PURPOSE: The purpose of this case report is to describe an intervention strategy focusing on gait retraining and hip and lumbopelvic stability for a female runner diagnosed with athletic pubalgia and a labral tear of the hip. CASE DESCRIPTION: This case report involved a 45-year-old female runner who was seen for 14 visits, from examination to return to sport, with a follow up at 12 months post discharge. Interventions included hip, pelvic, and lumbar stability exercises, and gait retraining. Outcomes measurements included: pain on the numeric pain rating scale, the Lower Extremity Functional Scale (LEFS), gait mechanics, strength, and participation in sport. OUTCOMES: At discharge the subject demonstrated improved strength of all muscle groups and changes in lower extremity running biomechanics. Changes in running mechanics included increased cadence, decreased pelvic drop, diminished over striding, and improved knee control with less valgus movement during the stance phase of gait. The subject reported no pain with running or recreational activities at discharge and follow up at 12 months post discharge. DISCUSSION/CONCLUSION: Most of the literature on conservative rehabilitation for athletic pubalgia focuses on athletes whose sports require pivoting and kicking. The literature provides little information on gait analysis and retraining for runners with a diagnosis of athletic pubalgia and/or hip labrum tears. The program used in this case report including gait retraining and hip, pelvic, and lumbar stability training allowed for full return to running in a 45-year-old female with a diagnosis of hip labrum tear and athletic pubalgia. Further research is needed to discern best conservative treatment for runners with athletic pubalgia and/or hip labral tears. LEVEL OF EVIDENCE: 4.

Long-term persistence of wildlife populations in a pastoral area.

Facilitating coexistence between people and wildlife is a major conservation challenge in East Africa. Some conservation models aim to balance the needs of people and wildlife, but the effectiveness of these models is rarely assessed. Using a case-study approach, we assessed the ecological performance of a pastoral area in northern Tanzania (Manyara Ranch) and established a long-term wildlife population monitoring program (carried out intermittently from 2003 to 2008 and regularly from 2011 to 2019) embedded in a distance sampling framework. By comparing density estimates of the road transect-based long-term monitoring to estimates derived from systematically distributed transects, we found that the bias associated with nonrandom placement of transects was nonsignificant. Overall, cattle and sheep and goat reached the greatest densities and several wildlife species occurred at densities similar (zebra, wildebeest, waterbuck, Kirk's dik-dik) or possibly even greater (giraffe, eland, lesser kudu, Grant's gazelle, Thomson's gazelle) than in adjacent national parks in the same ecosystem. Generalized linear mixed models suggested that most wildlife species (8 out of 14) reached greatest densities during the dry season, that wildlife population densities either remained constant or increased over the 17-year period, and that herbivorous livestock species remained constant, while domestic dog population decreased over time. Cross-species correlations did not provide evidence for interference competition between grazing or mixed livestock species and wildlife species but indicate possible negative relationships between domestic dog and warthog populations. Overall, wildlife and livestock populations in Manyara Ranch appear to coexist over the 17-year span. Most likely, this is facilitated by existing connectivity to adjacent protected areas, effective anti-poaching efforts, spatio-temporal grazing restrictions, favorable environmental conditions of the ranch, and spatial heterogeneity of surface water and habitats. This long-term case study illustrates the potential of rangelands to simultaneously support wildlife conservation and human livelihood goals if livestock grazing is restricted in space, time, and numbers.

Perception of recurrent stroke risk among black, white and Hispanic ischemic stroke and transient ischemic attack survivors: the SWIFT study.

OBJECTIVES: Risk modification through behavior change is critical for primary and secondary stroke prevention. Theories of health behavior identify perceived risk as an important component to facilitate behavior change; however, little is known about perceived risk of vascular events among stroke survivors. METHODS: The SWIFT (Stroke Warning Information and Faster Treatment) study includes a prospective population-based ethnically diverse cohort of ischemic stroke and transient ischemic attack survivors. We investigate the baseline relationship between demographics, health beliefs, and knowledge on risk perception. Regression models examined predictors of inaccurate perception. RESULTS: Only 20% accurately estimated risk, 10% of the participants underestimated risk, and 70% of the 817 study participants significantly overestimated their risk for a recurrent stroke. The mean perceived likelihood of recurrent ischemic stroke in the next 10 years was 51 ± 7%. We found no significant differences by race-ethnicity with regard to accurate estimation of risk. Inaccurate estimation of risk was associated with attitudes and beliefs [worry (p < 0.04), fatalism (p < 0.07)] and memory problems (p < 0.01), but not history or knowledge of vascular risk factors. CONCLUSION: This paper provides a unique perspective on how factors such as belief systems influence risk perception in a diverse population at high stroke risk. There is a need for future research on how risk perception can inform primary and secondary stroke prevention.

N-Acetylcysteine reverses cocaine-induced metaplasticity.

Cocaine addiction is characterized by an impaired ability to develop adaptive behaviors that can compete with cocaine seeking, implying a deficit in the ability to induce plasticity in cortico-accumbens circuitry crucial for regulating motivated behavior. We found that rats withdrawn from cocaine self-administration had a marked in vivo deficit in the ability to develop long-term potentiation (LTP) and long-term depression (LTD) in the nucleus accumbens core subregion after stimulation of the prefrontal cortex. N-acetylcysteine (NAC) treatment prevents relapse in animal models and craving in humans by activating cystine-glutamate exchange and thereby stimulating extrasynaptic metabotropic glutamate receptors (mGluR). NAC treatment of rats restored the ability to induce LTP and LTD by indirectly stimulating mGluR2/3 and mGluR5, respectively. Our findings show that cocaine self-administration induces metaplasticity that inhibits further induction of synaptic plasticity, and this impairment can be reversed by NAC, a drug that also prevents relapse.

Cystine/glutamate exchange regulates metabotropic glutamate receptor presynaptic inhibition of excitatory transmission and vulnerability to cocaine seeking.

Withdrawal from chronic cocaine reduces extracellular glutamate levels in the nucleus accumbens by decreasing cystine/glutamate exchange (xc-). Activating xc- with N-acetylcysteine restores extracellular glutamate and prevents cocaine-induced drug seeking. It was hypothesized that the activation of xc- prevents drug seeking by increasing glutamatergic tone on presynaptic group II metabotropic glutamate receptors (mGluR2/3) and thereby inhibiting excitatory transmission. In the first experiment, the capacity of glutamate derived from xc- to regulate excitatory transmission via mGluR2/3 was determined. Physiological levels of cystine (100-300 nm) were restored to acute tissue slices from the nucleus accumbens or prefrontal cortex. Cystine increased glutamate efflux and decreased miniature EPSC (mEPSC) and spontaneous EPSC (sEPSC) frequency as well as evoked EPSC amplitude. These effects of cystine were presynaptic, because there was no change in mEPSC or sEPSC amplitude, and an increase in the evoked EPSC paired-pulse facilitation ratio. The cystine-induced reduction in EPSCs was reversed by blocking either xc- or mGluR2/3. In the second experiment, blocking mGluR2/3 prevented the ability of N-acetylcystine to inhibit the reinstatement of drug seeking in rats trained to self-administer cocaine. These data demonstrate that nonsynaptic glutamate derived from xc- modulates synaptic glutamate release and thereby regulates cocaine-induced drug seeking.

Resting energy expenditure of rats acclimated to hypergravity.

BACKGROUND: The use of centrifugation at 1 G has been advocated as a control condition during spaceflight and as a countermeasure to compensate for the adverse effects of spaceflight. Rodents are the primary animal model for the study of the effects of spaceflight and will be used in the evaluation of centrifugation as a countermeasure and means of control at 1 G during flight. HYPOTHESIS: The present study was designed to assess whether resting energy expenditure (EER) of male rats was increased in relation to the magnitude of the level of gravity to which the animals were exposed. The influence of body mass and age on resting energy expenditure (EER) of male rats (n = 42, age 40-400 d) was determined following 2 wk of acclimation to 1, 2.3, or 4.1 G. Hypergravity environments were created by centrifugation. Measurements were made at the gravity level to which the animal was acclimated and during the lights-on period. RESULTS: In rats matched for body mass (approximately 400 g), mean O2 consumption and CO2 production were higher (18% and 27%, respectively) in the 2.3- and 4.1 -G groups than controls. Mean respiratory exchange ratio (RER) increased from 0.80 to 0.87. EER was increased from 47 +/- 0.1 kcal x d(-1) at 1 G, to 57 +/- 1.5 and 58 +/- 2.2 kcal x d(-1) at 2.3 and 4.1 G, respectively. There was no difference in EER between the hypergravity groups. When age differences were considered, EER (kcal x kg(-1) x d(-1)) with increased gravity was 40% higher than at 1 G. The increase in EER was not proportional over gravity levels. CONCLUSION: Acclimation of rats to hypergravity increases their EER, dependent on body mass and age, and may alter substrate metabolism. The increase in EER was not related to the level of gravity increase.