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Abstract Background Symbiosis is central to ecosystems and has been an important driving force of the diversity of life. Close and long-term interactions are known to develop cooperative molecular mechanisms between the symbiotic partners and have often given them new functions as symbiotic entities. In lichen symbiosis, mutualistic relationships between lichen-forming fungi and algae and/or cyanobacteria produce unique features that make lichens adaptive to a wide range of environments. Although the morphological, physiological, and ecological uniqueness of lichens has been described for more than a century, the genetic mechanisms underlying this symbiosis are still poorly known. Results This study investigated the fungal-algal interaction specific to the lichen symbiosis using Usnea hakonensis as a model system. The whole genome of U. hakonensis, the fungal partner, was sequenced by using a culture isolated from a natural lichen thallus. Isolated cultures of the fungal and the algal partners were co-cultured in vitro for 3 months, and thalli were successfully resynthesized as visible protrusions. Transcriptomes of resynthesized and natural thalli (symbiotic states) were compared to that of isolated cultures (non-symbiotic state). Sets of fungal and algal genes up-regulated in both symbiotic states were identified as symbiosis-related genes. Conclusion From predicted functions of these genes, we identified genetic association with two key features fundamental to the symbiotic lifestyle in lichens. The first is establishment of a fungal symbiotic interface: (a) modification of cell walls at fungal-algal contact sites; and (b) production of a hydrophobic layer that ensheaths fungal and algal cells;. The second is symbiosis-specific nutrient flow: (a) the algal supply of photosynthetic product to the fungus; and (b) the fungal supply of phosphorous and nitrogen compounds to the alga. Since both features are widespread among lichens, our result may indicate important facets of the genetic basis of the lichen symbiosis.

Abstract Background While traditional, complementary and alternative medicine (TCAM) is gaining increased interest worldwide, the structural factors associated with the usage of TCAM at the social level have not been sufficiently explored. We aim to understand the social structure of uncertainty in society that affects the TCAM usage for men and women. Methods We studied 32 countries using data from the International Social Survey Programme and the World Bank. In this study, we defined TCAM usage as visits to an alternative/traditional/folk health care practitioner during the past 12 months. We performed a correlation analysis and used a generalized linear model . Results The prevalence of TCAM usage in terms of visits to practitioners was 26.1% globally, while usage varied across the 32 countries. Generalized linear models showed that unemployment rate was associated with the prevalence of TCAM usage in terms of visits to practitioners. Conclusions At the social-structural level TCAM usage involving visits to practitioners was related to job insecurity. Job insecurity led to a decrease in TCAM usage regarding visits to practitioners. These findings suggest that it is necessary to consider the social-structural factors of uncertainty in society when designing health policies related to TCAM.