The covalent chemistry of reactants tethered within a single protein pore can be monitored by observing the time-dependence of ionic current flow through the pore, which responds to bond making and breaking in individual reactant molecules. Here we use this 'nanoreactor' approach to examine the reaction of a quinone with a thiol to form a substituted hydroquinone by reductive 1,4-Michael addition. Remarkably, a primary hydrogen-deuterium isotope effect is readily detected at the single-molecule level during prototropic rearrangement of an initial adduct. The observation of individual reaction intermediates allows the measurement of an isotope effect whether or not the step involved is rate limiting, which would not be the case in an ensemble measurement.
Biodiesel produced from woody oil plants is considered a green substitute for fossil fuels. However, a potential negative impact of growing woody oil plants on a large scale is the introduction of highly invasive species into susceptible regions. In this study, we examined the potential invasion risk of woody oil plants in China’s protected areas under future climate conditions. We simulated the current and future potential distributions of three invasive woody oil plants, Jatropha curcas, Ricinus communis, and Aleurites moluccana, under two climate change scenarios (RCP2.6 and RCP8.5) up to 2050 using species distribution models. Protected areas in China that will become susceptible to these species were then identified using a spatial overlay analysis. Our results showed that by 2050, 26 and 41 protected areas would be threatened by these invasive woody oil plants under scenarios RCP2.6 and RCP8.5, respectively. A total of 10 unique forest ecosystems and 17 rare plant species could be potentially affected. We recommend that the invasive potential of woody oil plants be fully accounted for when developing forest-based biodiesel, especially around protected areas.
Context Urban remnant forest exists as patches scattered in an urban matrix. They are important sites for urban biodiversity conservation. Nevertheless, it is unclear how the properties of the urban matrix affect the biodiversity of remnant patches. Objective Using data surveyed from 30 urban remnant forest patches in Guiyang, China, we intended to find out whether heterogeneity of the urban matrix affects the species richness of woody plants in these patches significantly. Methods We used landscape indices calculated from land cover data to quantify compositional and
Common ragweed (Ambrosia artemisiifolia L.) is an invasive alien species (IAS) that can cause severe allergies among urban residents. Understanding its invasion pathways is critical for designing effective control programs. However, studies on the invasion of common ragweed normally skip urban areas. Results from a few studies based on analyzing occurrence records contain high uncertainties. We attempted to address this knowledge gap through a case study in East China cities by combining the population genetic method with the occurrence records. We first collected leaf samples of 37 common ragweed populations from 15 cities. We then quantified the spatial genetic pattern of common ragweed populations by analyzing genomic and chloroplast DNA extracted from the leaf samples. Combined with the analysis of occurrence data and trade data, we discovered that multiple introductions have impacted the spatial genetic pattern of common ragweed populations in East China Cities. We inferred that the modern-day grain trade between the United States and China could be the primary invasion source while the bridgehead introduction passage through Japan played a minor role. Among the studied cities, Nanjing and Shenyang dispersed more gene flows than other cities. The two cities' central roles in transportation and grain importation might explain the observed pattern. Based on our findings, we suggest that invasive species control programs should consider the potential role of cities as landing points and dispersal hubs of common ragweed in invaded countries.
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