A testing ground for cyclopentannulation strategies: the triquinane natural product hirsutene is obtained through the intramolecular organocatalytic [3+2] cycloaddition of the 1,7‐enyne (E)‐1 . The cycloaddition is stereospecific: reaction of the corresponding Z isomer provides the epimeric diquinane.
Aim
Evolutionary processes of mountain plants in arid lands remain poorly understood. Here, we investigate population genomics of the endangered wild apple tree to interpret the effects of long‐term aridification on plant diversification and demographical history in Central Asian Mountains.
Location
The Tianshan Mountains, spanning north‐western China, Kazakhstan, Kyrgyzstan and Tajikistan.
Taxon
Malus sieversii (Rosaceae)
Methods
Using genome‐wide single nucleotide polymorphisms, we assessed genetic diversity and genetic structure of 15 populations across the species' range. Demographical history was simulated with approximate Bayesian computation and species distribution modelling. We used a general linear model to identify key environmental factors affecting population genetic diversity and structure.
Results
We separated the 15 populations into three groups: the eastern group of western Junggar Mountains in China; the central group of the Ili Valley, the Talas Alatau Mountains in Kazakhstan and Kyrgyzstan; and the western group of Tajikistan and the Dzungarian Alatau in Kazakhstan. Central populations had higher genetic diversity and effective population size than eastern and western populations. The three groups split at the late Miocene and subsequently experienced extensive admixture. We detected a significant pattern of isolation by distance, but not isolation by environment, among these populations. Population genetic diversity was significantly associated with longitudinal and current environmental gradients.
Main conclusions
Long‐term aridification promoted distribution fragmentation and plant lineage divergence of relict broad‐leaved forests in Central Asian Mountains. Both geographical isolation and environmental heterogeneity shaped spatial patterns in genetic variation among M. sieversii populations. To maintain genetic integrity, we propose the establishment of an international network for the conservation of this endangered wild apple tree.
Substituted furans are synthesized by phosphine-mediated reductive condensation of γ-acyloxy butynoates. The method represents a powerful and mechanistically novel protocol for the convergent three-component construction of the title compounds. -(JUNG, C.-K.; WANG, J.-C.; KRISCHE*, M. J.; J. Am. Chem. Soc. 126 (2004) 13, 4118-4119; Dep. Chem. Biochem., Univ. Tex., Austin, TX 78712, USA; Eng.) -S. Adam 31-107
Cyclopentane derivativesCyclopentane derivatives Q 0030 Catalytic Diastereoselective Synthesis of Diquinanes from Acyclic Precursors. -A new method for the preparation of bicyclo(3.3.0) ring systems by intramolecular phosphine-catalyzed [3 + 2] cycloaddition of electron-deficient 1,7-enynes is presented. With the exception of ether containing enyne (Ie) all substrates provide cycloadducts in > 90% d.e. Attempted cycloaddition of the corresponding 1,8-enynes resulted in dramatically reduced diastereoselectivities and yields. -(WANG, J.-C.; NG, S.-S.; KRISCHE*, M. J.; J. Am. Chem. Soc. 125 (2003) 13, 3682-3683; Dep. Chem. Biochem., Univ. Tex., Austin, TX 78712, USA; Eng.) -Bartels 32-057
Resveratrol (RSV) has been shown to have a neuroprotective effect in various central nervous system disorders, although the role of RSV in diabetes-induced cognitive dysfunction is still not fully elucidated. Here, we investigated whether RSV improved diabetes-related cognitive dysfunction in vivo and in vitro. We induced a rat diabetic model with a high-fat and high-sucrose diet followed by intraperitoneal injection of streptozotocin and a diabetic neuron cell model by stimulation with high levels of glucose. We observed that RSV improved impairment in spatial learning and memory in the Morris water maze test (MWM) and novel object recognition test (ORT) in diabetic rats. RSV reversed the reduced miR-146a-5p and upregulated thioredoxin-interacting protein (TXNIP) and inhibited the diabetes-induced increase in interleukin (IL)-1β and tumor necrosis factor (TNF)-α levels in vivo and in vitro. RSV also inhibited diabetes-induced endoplasmic reticulum stress (ESR) by reducing ESR-related protein expression in vivo and in vitro. Moreover, inhibition of miR-146a-5p partially abolished the protective effects of RSV in HG-treated primary neurons. Additionally, we used starBase to predict that miR-146a-5p interacts with TXNIP, which we then verified using a luciferase reporter gene assay. We further observed that miR-146a-5p regulates the mRNA and protein expression of TXNIP in vitro, indicating that the miR-146a-5p/TXNIP axis is involved in the regulation of cognitive dysfunction in a rat diabetic model. Collectively, these results demonstrate that RSV plays a neuroprotective role in diabetes-associated cognitive dysfunction at least in part through regulation of the miR-146a-5p/TXNIP axis.
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.