Tea plants and air pollutants

The major tea-growing regions of the world are located in Asia, where tea contributes substantially to their economy. It is known how the rapid development of the economy, twinned to global change, has created in many districts of industrialized countries critical levels of air pollution. Abiotic stresses may affect plant growth, quality, and distribution. This is particularly important for specialty crops such as tea, where functional quality is determined by phytonutrients, secondary metabolites, and bioactive components that play a pivotal role in plant defense and acclimation/adaptation/resilience to environmental stresses. Stress conditions such as drought, heat, light extremes, salinity, and toxic metals in the substrate have been the subject of intense researches, and the sensitivity of tea plants to these constraints has been tested by the scientific community through field and controlled experiments. Tea plants present high leaf surface areas, and exchange with atmosphere is elevated. However, little is known about the way air pollution affects tea responses and how this species is able to counteract this insult. In this chapter, the existing literature reporting the effects of air pollution on the tea plant is reviewed with the aim to examine physiological, biochemical, and molecular responses found in this species. To the best of our knowledge, only the impacts of few air pollutants have been somehow assessed on tea plants, and several responses are still poorly understood. Thus, more research on the impact of air pollution on tea plants is needed. This is of pivotal importance also because commercial tea samples may contain significant quantities of contaminants, which may be transferred to the consumer. No doubt that health national/international bodies should pay more attention to this issue and adopt safe standards of pollution content in the commodities of one of the world’s most popular beverages, highly appreciated also by young people because of its pleasant aroma, flavor, and potential positive effect on mood

Exoplanetary Biosignatures for Astrobiology

Since life evolved on our planet there have been subtle interplays between biology and Earth System Components (atmosphere-lithosphere-ocean-interior). Life, for example, can impact weathering rates which, in turn, influence climate stabilizing feedback cycles on Earth. Photosynthesis is ultimately responsible for our oxygen-rich atmosphere, which favours the formation of the protective ozone layer. The recent rise of exoplanetary science has led to a re-examination of such feedbacks and their main drivers under different planetary conditions. In this work we present a brief overview of potential biosignatures (indicators of life) and review knowledge of the main processes, which influence them in an exoplanetary context. Biosignature methods can be broadly split into two areas, namely “in-situ” and “remote”. Criteria employed to detect biosignatures are diverse and include fossil morphology, isotope ratios, patterns in the chemical constituents of cells, degree of chirality, shifts from thermal or redox equilibrium, and changes in the abundance of atmospheric species. For the purposes of this review, our main focus lies upon gas-phase species present in Earth-like atmospheres, which could be detected remotely by spectroscopy. We summarize current knowledge based on the modern (and early) Earth and the Solar System then review atmospheric model studies for Earth-like planets, which predict climate, photochemistry and potential spectral signals of biosignature species

Muramyl dipeptide responsive pathways in Crohn’s disease: from NOD2 and beyond

Crohn's disease (CD) is one of main disease entities under the umbrella term chronic inflammatory bowel disease. The etiology of CD involves alterations in genetic, microbiological, and immunological factors. This review is devoted to the role of the bacterial wall compound muramyl dipeptide (MDP) for the activation of inflammatory pathways involved in the pathogenesis of CD. The importance of this molecule is underscored by the fact that (1) MDP, which is found in most Gram-negative and -positive bacteria, is able to trigger several immunological responses in the intestinal system, and (2) that alterations in several mediators of the MDP response including-but not restricted to-nucleotide oligomerization domain 2 (NOD2) are associated with CD. The normalization of MDP signaling is one of several important factors that influence the intestinal inflammatory response, a fact which emphasizes the pathogenic importance of MDP signaling for the pathogenesis of CD. The important aspects of NOD2 and non-NOD2 mediated effects of MDP for the development of CD are highlighted, as well as how alterations in these pathways might translate into the development of new therapeutic strategies