The biochemical responses of Holcus lanatus L. to copper and arsenate exposure were investigated in arsenatetolerant and -non-tolerant plants from uncontaminated and arsenic/copper-contaminated sites. Increases in lipid peroxidation, superoxide dismutase (SOD) activity and phytochelatin (PC) production were correlated with increasing copper and arsenate exposure. In addition, significant differences in biochemical responses were observed between arsenate-tolerant and -non-tolerant plants. Copper and arsenate exposure led to the production of reactive oxygen species, resulting in significant lipid peroxidation in non-tolerant plants. However, SOD activity was suppressed upon metal exposure, possibly due to interference with metallo-enzymes. It was concluded that in non-tolerant plants, rapid arsenate influx resulted in PC production, glutathione depletion and lipid peroxidation. This process would also occur in tolerant plants, but by decreasing the rate of influx, they were able to maintain their constitutive functions, detoxify the metals though PC production and quench reactive oxygen species by SOD activity.
(A.A.M.) Arsenate tolerance is conferred by suppression of the high-affinity phosphate/arsenate uptake system, which greatly reduces arsenate influx in a number of higher plant species. Despite this suppressed uptake, arsenate-tolerant plants can still accumulate high levels of As over their lifetime, suggesting that constitutive detoxification mechanisms may be required. Phytochelatins are thiol-rich peptides, whose production is induced by a range of metals and metalloids including arsenate. This study provides evidence for the role of phytochelatins in the detoxification of arsenate in arsenate-tolerant Holcus lanatus. Elevated levels of phytochelatin were measured in plants with a range of tolerance to arsenate at equivalent levels of arsenate stress, measured as inhibition of root growth. The results suggest that arsenate tolerance in H. lanatus requires both adaptive suppression of the high-affinity phosphate uptake system and constitutive phytochelatin production.
Many protected areas worldwide are mandated to provide visitor enjoyment and sustainable heritage conservation but face growing challenges and competition. To satisfy modern aspirational markets, parks must design meaningful experiences delivering long-lasting participant benefits that cultivate visitation rates and a conservation constituency. Transformative travel can deliver such benefits through participants' psycho-physiological transformation but market insights critical for experience development in parks are lacking. Our systematic quantitative review of 126 transformative travel articles provides those insights, linking experiential characteristics, participant traits and motivations to experience outcomes according to five transformative travel typologies pertinent to parks: health and wellness, nature-based physical activity, spiritual, cultural and volunteering travel. We identified 35 travel motivations, 14 participant traits and 23 experience characteristics linked to transformation and 28 purposefully or incidentally realised benefits. Transformative travel improved participants' psychological, physiological, social, economic and environmental conditions, as well as satisfaction with and destination loyalty towards parks. Socio-demographic characteristics and propensity for independent versus social travel shaped choice of travel experience. Our results are uniquely conceptualised in a transformative travel framework and transformative market niche model which we apply to sustainable experience development and marketing in parks. We identify implementation possibilities and areas for future research and monitoring.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.