Climate heterogeneity, season variation, and sexual dimorphism modulate the association between MHC II diversity and parasite variation in striped hamster.

Parasite-mediated selection is widely believed to play a crucial role in maintaining the diversity of the major histocompatibility complex (MHC) genes, which is thought to be maintained through heterozygote advantage, rare-allele advantage, and fluctuating selection. However, the relationship between parasite pressure and MHC diversity has yielded inconsistent findings. These inconsistencies may arise from the influence of environmental factors and individual variations in traits on host-parasite interactions. To address these issues, our study extensively investigated populations of striped hamsters inhabiting regions characterized by environmental heterogeneity. The primary objective was to examine the universality of parasite-mediated selection mechanisms. Our observations revealed the presence of multiple parasite infections, accompanied by spatial and temporal variations in parasite communities and infection patterns among individual hamsters. Specifically, the temperature was found to influence all four parasite indices, while the presence of gamasid mites and parasite richness decreased with increasing precipitation. We also noted significant seasonal variation in parasite dynamics. Moreover, a significant sexual dimorphism was observed with males exhibiting a considerably higher parasite burden compared to their female counterparts. Lastly, we identified the maintenance of MHC polymorphism in striped hamsters as being driven by the heterozygote advantage and fluctuating selection mechanisms. This study underscores the significance of ecological processes in comprehending host-parasite systems and highlights the necessity of considering environmental factors and individual traits when elucidating the mechanisms underlying MHC diversity mediated by parasites.

Neutral Forces and Balancing Selection Interplay to Shape the Major Histocompatibility Complex Spatial Patterns in the Striped Hamster in Inner Mongolia: Suggestive of Broad-Scale Local Adaptation.

BACKGROUND: The major histocompatibility complex (MHC) plays a key role in the adaptive immune response to pathogens due to its extraordinary polymorphism. However, the spatial patterns of MHC variation in the striped hamster remain unclear, particularly regarding the relative contribution of the balancing selection in shaping MHC spatial variation and diversity compared to neutral forces. METHODS: In this study, we investigated the immunogenic variation of the striped hamster in four wild populations in Inner Mongolia which experience a heterogeneous parasitic burden. Our goal was to identify local adaptation by comparing the genetic structure at the MHC with that at seven microsatellite loci, taking into account neutral processes. RESULTS: We observed significant variation in parasite pressure among sites, with parasite burden showing a correlation with temperature and precipitation. Molecular analysis revealed a similar co-structure between MHC and microsatellite loci. We observed lower genetic differentiation at MHC loci compared to microsatellite loci, and no correlation was found between the two. CONCLUSIONS: Overall, these results suggest a complex interplay between neutral evolutionary forces and balancing selection in shaping the spatial patterns of MHC variation. Local adaptation was not detected on a small scale but may be applicable on a larger scale.

Association between self-reported oral health and cognitive function among the community-dwelling elderly in Jinan, China: the mediating effect of life satisfaction.

Background: Deterioration of self-reported oral health and decline in cognitive function are two main adverse health outcomes experienced by the older adults. Little evidence was found on the psychosocial mechanism between self-reported oral health and cognitive function. This study explores the association between self-reported oral health and cognitive function and examines the mediating effect of life satisfaction among the community-dwelling elderly in Jinan, China. Methods: A total of 512 older individuals (60+) were included in the study. Cognitive function was assessed using the Chinese version of the Mini-Mental State Examination scale (MMSE), and self-reported oral health was measured using the Chinese version of the Geriatric Oral Health Assessment Index (GOHAI). Pearson correlation analysis was used to determine the relationship between self-reported oral health, life satisfaction, and cognitive function. Multivariate linear regression analysis was conducted to explore the possible effect of covariates. Structural equation modelling and Bootstrap analyses were conducted to verify the mediating role of life satisfaction. Results: The mean MMSE score was 25.65 ± 4.42. Better self-reported oral health was significantly associated with a higher level of life satisfaction, and those with higher life satisfaction experienced better cognitive function. Age, educational level and source of living expenses were found to be cofounding variables. Life satisfaction partially mediated the effect of self-reported oral health on cognitive function (95% confidence interval [CI]: 0.010 to 0.075). The mediating effect of life satisfaction accounted for 24% of the total effect. Conclusion: The level of cognitive function was relatively high. Self-reported oral health was positively associated with cognitive function, and the mediating effect of life satisfaction was proven to exist in the community-dwelling older individuals. Early screening for oral diseases and a greater focus on life satisfaction are recommended.

Effects of childcare disagreement with children, social support, and health status on unmet healthcare-seeking behavior among the migrant older with children to Jinan, China.

Due to the acceleration of China's urbanization, the number of migrant older with children (MOC) continued to increase. This study aimed to clarify the effects of childcare disagreement with children, social support, and health status on unmet healthcare-seeking behavior among the MOC to Jinan, China. A cross-sectional study included 656 MOC (36.3% men and 63.7% women) using multi-stage cluster random sampling in Jinan, China. Childcare disagreement was evaluated by the differences between parents and grandparents on the diet, dressing, education, and childcare consumption. Social support was assessed using the social support rating scale (SSRS). Descriptive analysis, chi-squared test, and binary logistic regression were applied to analyze the association between childcare disagreement with children, social support, health status, and unmet healthcare-seeking behavior of the MOC. Approximately 41.3% of participants had unmet healthcare-seeking behavior. Logistic regression analysis showed that the MOC whose health status compared to last year get better were more likely to have unmet healthcare-seeking behavior, while who were women, had partial will of migration, hired a nanny, had smaller childcare disagreement with children on dressing, had smaller childcare disagreement with children on consumption, and had moderate social support, were less likely to experience unmet healthcare-seeking behavior. Recommendations were given to the government and family members to improve the health services-seeking behavior of the MOC.

Mediating effect of family support on the relationship between acculturation and loneliness among the migrant elderly following children in Jinan, China.

The total number of migrant elderly following children (MEFC) has gradually increased along with population aging and urbanization in recent decades in China. The purpose of this study was to investigate the mediating effect of family support on the relationship between acculturation and loneliness among the MEFC in Jinan, China. A total of 656 MEFC were selected by multistage cluster random sampling. Loneliness was measured using the short-form UCLA Loneliness Scale (ULS-8), while acculturation and family support were assessed using a self-designed questionnaire. Descriptive analysis, univariate analysis, and the structural equation model (SEM) were conducted to illustrate the relationship between the above indicators and loneliness. The average ULS-8 score of the MEFC was 12.82 ± 4.05 in this study. Acculturation of the MEFC exerted a negatively direct effect on loneliness and a positively direct effect on family support simultaneously, while family support exerted a negatively direct effect on loneliness. Family support partially mediated the relationship between acculturation and loneliness [95% CI: -0.079 to 0.013, p < 0.001], while the mediating effect of family support accounted for 14.0% of the total effect. The average ULS-8 score of 12.82 ± 4.05 implied a low level of loneliness in the MEFC in Jinan, China. Acculturation was found to be correlated with loneliness, while the mediating role of family support between acculturation and loneliness was established. Policy recommendations were provided to reduce loneliness and improve the acculturation and family support of the MEFC according to the findings above.