Mechanisms underlying the relationship between the intersectionality of multiple social identities with depression among US adults: A population-based study on the mediating roles of lifestyle behaviors.

BACKGROUND: Despite substantial efforts to investigate the inequalities in mental health among people with marginalized identities, most research has concentrated on single social identities rather than complete persons. The current study aimed to explore the mechanisms underlying the relationship between the intersectionality of multiple social identities with depression among US adults. METHODS: Data for this study came from the National Health and Nutrition Examination Survey waves between 2015 and 2018, including a total of 11,268 US adults. A latent class analysis (LCA) was conducted to identify latent subpopulations based on sex, race/ethnicity, immigrant status, disability, household income, employment status, and education level. Interclass differences in lifestyle factors and depression were examined. Multiple mediation analysis was used to examine the mediating roles of lifestyle behaviors. RESULTS: LCA identified four potential subpopulations: "least marginalized", "immigrant minorities", "disabled, less-educated non-workers", and "low-income minorities" groups. There was enormous heterogeneity in mental health among immigrant minority individuals. The "disabled, less-educated non-workers" group had the highest rates of depression; in contrast, the "immigrant minorities" group had the best mental health, even better than that of the "least marginalized" group. Distributions of lifestyle factors followed a similar pattern. In addition, lifestyle behaviors significantly mediated the relationship between intersectional social identities and depression. LIMITATIONS: The cross-sectional design prevented establishment of the causality of relationships. CONCLUSIONS: This study suggests that applying a person-centered approach is important when examining intersectional inequalities in mental health and highlights the effects of structural social hierarchies on individuals' health behaviors and mental health.

Associations of Lifestyle Patterns With Overweight and Depressive Symptoms Among United States Emerging Adults With Different Employment Statuses.

Objective: To identify lifestyle patterns in emerging adults and examine the association of lifestyle patterns with overweight and depression. Methods: Data was from the National Health and Nutrition Examination Survey between 2011 and 2018. A latent class analysis (LCA) was conducted with 2,268 US emerging adults based on sedentary behavior, moderate-to-vigorous physical activity, diet, sleep, alcohol drinking, and cigarette smoking. The associations of lifestyle groups with overweight and depression were examined by logistic regression and were further stratified by employment status. Results: The LCA results favored a four-class solution: "unhealthy but non-substance use" (59%), "healthy but sleepless and drinking" (12%), "unhealthy lifestyle" (15%), and "healthy but sedentary" group (14%). Compared to the "unhealthy lifestyle" group, participants in the "unhealthy but non-substance use" (coef. = -1.44, SE = 0.27; OR = 0.40, 95% CI [0.26, 0.61]), "healthy but sleepless and drinking" (coef. = -1.49, SE = 0.35; OR = 0.38, 95% CI [0.20, 0.72]), and "healthy but sedentary" (coef. = -1.97, SE = 0.34; OR = 0.29, 95% CI [0.14, 0.57]) groups had lower depression severity and reported fewer depressive symptoms. Moreover, lifestyle groups and health outcomes showed different relationships among employed and unemployed participants. Conclusion: This study found that the combinations of lifestyle behaviors had synergistic effects on mental health, and such effects differed by employment status.

Symbiosis between Dendrobium catenatum protocorms and Serendipita indica involves the plant hypoxia response pathway.

Mycorrhizae are ubiquitous symbioses established between fungi and plant roots. Orchids, in particular, require compatible mycorrhizal fungi for seed germination and protocorm development. Unlike arbuscular mycorrhizal fungi, which have wide host ranges, orchid mycorrhizal fungi are often highly specific to their host orchids. However, the molecular mechanism of orchid mycorrhizal symbiosis is largely unknown compared to that of arbuscular mycorrhizal and rhizobial symbiosis. Here, we report that an endophytic Sebacinales fungus, Serendipita indica, promotes seed germination and the development of protocorms into plantlets in several epiphytic Epidendroideae orchid species (6 species in 2 genera), including Dendrobium catenatum, a critically endangered orchid with high medicinal value. Although plant-pathogen interaction and high meristematic activity can induce the hypoxic response in plants, it has been unclear whether interactions with beneficial fungi, especially mycorrhizal ones, also involve the hypoxic response. By studying the symbiotic relationship between D. catenatum and S. indica, we determined that hypoxia-responsive genes, such as those encoding alcohol dehydrogenase (ADH), are highly induced in symbiotic D. catenatum protocorms. In situ hybridization assay indicated that the ADH gene is predominantly expressed in the basal mycorrhizal region of symbiotic protocorms. Additionally, the ADH inhibitors puerarin and 4-methylpyrazole both decreased S. indica colonization in D. catenatum protocorms. Thus, our study reveals that S. indica is widely compatible with orchids and that ADH and its related hypoxia-responsive pathway are involved in establishing successful symbiotic relationships in germinating orchids.

MITOCHONDRIA: The dual function of the transient receptor potential melastatin 2 channels from cytomembrane to mitochondria.

Mitochondria are closely related to oxidative stress and play an important role in maintaining cell functional homeostasis and meeting cell energy demand. The transient receptor potential melastatin 2 (TRPM2) channel affects the occurrence and progression of diseases by regulating mitochondrial function. TRPM2 channel promotes Ca2+ influx to affect 18 kDa translocator protein (TSPO), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), adenosine triphosphate (ATP) production, and mitochondrial autophagy. The mechanism of Ca2+ influx into the mitochondria by TRPM2 is abundant. Interestingly, the TRPM2 channel inhibits the production of mitochondrial ROS in cancer cells and promotes the production of mitochondrial ROS in normal cells, which induces cell death in normal cells but proliferation in cancer cells. TRPM2 can be a potential target for the treatment of various diseases due to its role as a molecular link between mitochondria and Ca2+ signals.

Regulatory Effects of Clock and Bmal1 on Circadian Rhythmic TLR Expression.

Circadian locomotor output cycles kaput (Clock) and brain and muscle ARNT-like 1 (Bmal1) are two core circadian clock genes. They form a heterodimer that can bind to the E-box element in the promoters of Period circadian protein (Per) and Cryptochrome (Cry) genes, thereby inducing the rhythmic expression of circadian clock control genes. Toll-like receptors (TLRs) are type I transmembrane proteins belonging to the pattern recognition receptor (PRR) family. They can recognize a variety of pathogens and play an important role in innate immunity and adaptive immune responses. Recent studies have found that the circadian clock is closely associated with the immune system. TLRs have a certain correlation with the circadian rhythms; Bmal1 seems to be the central mediator connecting the circadian clock and the immune system. Research on Bmal1 and TLRs has made some progress, but the specific relationship between TLRs and Bmal1 remains unclear. Understanding the relationship between TLRs and Clock/Bmal1 genes is increasingly important for basic research and clinical treatment.

Transitions between the Terrestrial and Epiphytic Habit Drove the Evolution of Seed-Aerodynamic Traits in Orchids.

Orchids are globally distributed, a feature often attributed to their tiny dustlike seeds. They were ancestrally terrestrial but in the Eocene expanded into tree canopies, with some lineages later returning to the ground, providing an evolutionarily replicated system. Because seeds are released closer to the ground in terrestrial species than in epiphytic ones, seed traits in terrestrials may have been under selective pressure to increase seed dispersal efficiency. In this study, we test the expectations that seed airspace-a trait known to increase seed flotation time in the air-is (i) larger in terrestrial lineages and (ii) has increased following secondary returns to a terrestrial habit. We quantified and scored 20 seed traits in 121 species and carried out phylogenetically informed analyses. Results strongly support both expectations, suggesting that aerodynamic traits even in dust seeds are under selection to increase dispersal ability, following shifts in average release heights correlated with changes in habit.

Using In Situ Symbiotic Seed Germination to Restore Over-collected Medicinal Orchids in Southwest China.

Due to increasing demand for medicinal and horticultural uses, the Orchidaceae is in urgent need of innovative and novel propagation techniques that address both market demand and conservation. Traditionally, restoration techniques have been centered on ex situ asymbiotic or symbiotic seed germination techniques that are not cost-effective, have limited genetic potential and often result in low survival rates in the field. Here, we propose a novel in situ advanced restoration-friendly program for the endangered epiphytic orchid species Dendrobium devonianum, in which a series of in situ symbiotic seed germination trials base on conspecific fungal isolates were conducted at two sites in Yunnan Province, China. We found that percentage germination varied among treatments and locations; control treatments (no inoculum) did not germinate at both sites. We found that the optimal treatment, having the highest in situ seed germination rate (0.94-1.44%) with no significant variation among sites, supported a warm, moist and fixed site that allowed for light penetration. When accounting for seed density, percentage germination was highest (2.78-2.35%) at low densities and did not vary among locations for the treatment that supported optimal conditions. Similarly for the same treatment, seed germination ranged from 0.24 to 5.87% among seasons but also did vary among sites. This study reports on the cultivation and restoration of an endangered epiphytic orchid species by in situ symbiotic seed germination and is likely to have broad application to the horticulture and conservation of the Orchidaceae.

Rain pollination provides reproductive assurance in a deceptive orchid.

BACKGROUND AND AIMS: Abiotic pollination by wind or water is well established in flowering plants. In some species pollination by rain splashes, a condition known as ombrophily, has been proposed as a floral strategy. However, evidence for this type of abiotic pollination has remained controversial and many reported cases have subsequently been shown to be false. This study investigates ombrophily in the deceptive orchid Acampe rigida to determine the mechanism by which this species is able to maintain high fecundity, despite flowering during the rainy season in south-west China when pollinators are scarce. METHODS: The floral mechanisms promoting rain pollination in A. rigida were observed and described in detail. Controlled pollination experiments and observations of floral visitors were conducted. A field experiment using rain shelters at 14 sites in Guangxi, south-west China, evaluated the contribution of rain pollination to fruit-set. KEY RESULTS: During rainfall, raindrops physically flicked away the anther cap exposing the pollinarium. Raindrops then caused pollinia to be ejected upwards with the strap-like stipe pulling them back and causing them to fall into the stigmatic cavity, resulting in self-pollination. Neither flower nor pollen function were damaged by water. Although A. rigida is self-compatible, it is incapable of autonomous self-pollination without the assistance of rain splashes. The results of the rain-sheltering experiment indicated that rain pollination contributed substantially to increasing fruit-set, although there was variation among sites in the intensity of this effect. CONCLUSIONS: A. rigida flowers during the rainy season, when pollinators are scarce, and ombrophily functions to provide reproductive assurance without compromising opportunities for outcrossing.