Rapid recovery of photosynthesis and water relations following soil drying and re-watering is related to the adaptation of desert shrub Ephedra alata subsp. alenda (Ephedraceae) to arid environments

Ephedra alata subsp. alenda is the most important pioneer plant of the moving and semi-stable sand dunes in the deserts and steppes of south Tunisia and occurs naturally in the Grand Erg Oriental, one of the most extreme habitats for plant growth on the planet. A new analysis of physiological performance of this medically important and internationally threatened xerophytic shrub was conducted to assess possible mechanisms of drought tolerance and how these relate to its ecological success. Five-month old plants, grown under controlled climatic conditions, were subjected to a well-watered control treatment or progressive drought by withholding water for 14d with subsequent recovery for 7d. Soil water depletion significantly reduced stem relative water content (RWC) water potential (Ψw) and osmotic potential (Ψπ). Ephedra displayed more negative Ψw and Ψπ values of ca. -3.5 and -4.1MPa, respectively, at the end of the drought treatment, and were associated with turgor loss. Low stem Ψw reduced stomatal conductance (gs), photosynthetic CO2 assimilation rates (ACO2), transpiration (E) and internal CO2 concentration (Ci). However, instantaneous (WUE; ACO2 E-1) and intrinsic (WUEi; ACO2 gs-1) water use efficiency (WUE) increased gradually as water deficit was intensified. Stomatal closure therefore only exerted limited control against dehydration and could not compensate for decreases in soil water status, typical of anisohydric behavior. Drought-stressed stems accumulated high levels of proline up to 480% of control values, highlighting a pivotal role in osmotic adjustment during intense water deficit. In contrast, the osmotic adaptation to soluble sugars was limited. Drought-stressed plants increased ACO2, E, gs and Ci and decreased WUE and WUEi during the first 48h after re-watering, such that they reached similar values to those of control plants by the end of the experiment. Stem proline levels of drought-stressed plants returned to near control values with re-watering. Overall, rapid recovery of photosynthesis following drought-breaking moisture appears to be a critical mechanism allowing E. alata to withstand and survive dry environments

Bioavailability of Plant-Derived Antioxidants

Natural products with antioxidant properties have been extensively utilized in the pharmaceutical and food industry and have also been very popular as health-promoting herbal products. This review provides a summary of the literature published around the first decade of the 21st century regarding the oral bioavailability of carotenoids, polyphenols and sulfur compounds as the three major classes of plant-derived antioxidants. The reviewed original research includes more than 40 compounds belonging to the above mentioned classes of natural antioxidants. In addition, related reviews published during the same period have been cited. A brief introduction to general bioavailability-related definitions, procedures and considerations is also included

The Potential Role of School Citizen Science Programs in Infectious Disease Surveillance: A Critical Review

Public involvement in science has allowed researchers to collect large-scale and real-time data and also engage citizens, so researchers are adopting citizen science (CS) in many areas. One promising appeal is student participation in CS school programs. In this literature review, we aimed to investigate which school CS programs exist in the areas of (applied) life sciences and if any projects target infectious disease surveillance. This review’s objectives are to determine success factors in terms of data quality and student engagement. After a comprehensive search in biomedical and social databases, we found 23 projects. None of the projects found focused on infectious disease surveillance, and the majority centered around species biodiversity. While a few projects had issues with data quality, simplifying the protocol or allowing students to resubmit data made the data collected more usable. Overall, students at different educational levels and disciplines were able to collect usable data that was comparable to expert data and had positive learning experiences. In this review, we have identified limitations and gaps in reported CS school projects and provided recommendations for establishing future programs. This review shows the value of using CS in collaboration with traditional research techniques to advance future science and increasingly engage communities