Chemical constituents from Abutilon indicum

The investigation on the chemical constituents of the whole plant of Abutilon indicum has resulted in the isolation of two new compounds, abutilin A (1) and (R)-N-(1'-methoxycarbonyl-2'-phenylethyl)-4-hydroxybenzamide (2), as well as 28 known compounds. The structures of the two new compounds were established on the basis of the spectroscopic analysis, and the known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature.     

Effects of low-frequency stimulation of the subthalamic nucleus on movement in Parkinson's disease

Excessive synchronization of basal ganglia neural activity at low frequencies is considered a hallmark of Parkinson's disease (PD). However, few studies have unambiguously linked this activity to movement impairment through direct stimulation of basal ganglia targets at low frequency. Furthermore, these studies have varied in their methodology and findings, so it remains unclear whether stimulation at any or all frequencies < or = 20 Hz impairs movement and if so, whether effects are identical across this broad frequency band. To address these issues, 18 PD patients chronically implanted with deep brain stimulation (DBS) electrodes in both subthalamic nuclei were stimulated bilaterally at 5, 10 and 20 Hz after overnight withdrawal of their medication and the effects of the DBS on a finger tapping task were compared to performance without DBS (0 Hz). Tapping rate decreased at 5 and 20 Hz compared to 0 Hz (by 11.8+/-4.9%, p=0.022 and 7.4+/-2.6%, p=0.009, respectively) on those sides with relatively preserved baseline task performance. Moreover, the coefficient of variation of tap intervals increased at 5 and 10 Hz compared to 0 Hz (by 70.4+/-35.8%, p=0.038 and 81.5+/-48.2%, p=0.043, respectively). These data suggest that the susceptibility of basal ganglia networks to the effects of excessive synchronization may be elevated across a broad low-frequency band in parkinsonian patients, although the nature of the consequent motor impairment may depend on the precise frequencies at which synchronization occurs.     

Improving the coverage of the cyanobacterial phylum using diversity-driven genome sequencing

The cyanobacterial phylum encompasses oxygenic photosynthetic prokaryotes of a great breadth of morphologies and ecologies; they play key roles in global carbon and nitrogen cycles. The chloroplasts of all photosynthetic eukaryotes can trace their ancestry to cyanobacteria. Cyanobacteria also attract considerable interest as platforms for “green” biotechnology and biofuels. To explore the molecular basis of their different phenotypes and biochemical capabilities, we sequenced the genomes of 54 phylogenetically and phenotypically diverse cyanobacterial strains. Comparison of cyanobacterial genomes reveals the molecular basis for many aspects of cyanobacterial ecophysiological diversity, as well as the convergence of complex morphologies without the acquisition of novel proteins. This phylum-wide study highlights the benefits of diversity-driven genome sequencing, identifying more than 21,000 cyanobacterial proteins with no detectable similarity to known proteins, and foregrounds the diversity of light-harvesting proteins and gene clusters for secondary metabolite biosynthesis. Additionally, our results provide insight into the distribution of genes of cyanobacterial origin in eukaryotic nuclear genomes. Moreover, this study doubles both the amount and the phylogenetic diversity of cyanobacterial genome sequence data. Given the exponentially growing number of sequenced genomes, this diversity-driven study demonstrates the perspective gained by comparing disparate yet related genomes in a phylum-wide context and the insights that are gained from it.The Cyanobacteria are one of the most diverse and widely distributed phyla of bacteria. Among photosynthetic prokaryotes, they uniquely have the ability to perform oxygenic photosynthesis; they are considered to be the progenitor of the chloroplast, the photosynthetic organelle found in eukaryotes. Cyanobacteria contribute greatly to global primary production, fixing a substantial amount of biologically available carbon, especially in nutrient-limited environmental niches, from oligotrophic marine surfaces to desert crusts (1, 2). In addition, cyanobacteria are key contributors to global nitrogen fixation (3), and many produce unique secondary metabolites (4). Despite these important traits and substantial interest in developing cyanobacterial strains for biotechnology, there is a paucity and unbalanced distribution of publicly available genomic information from the Cyanobacteria: 40% (29 of 72 species) of the available genomes fall within the closely related marine Prochlorococcus/Synechococcus subclade. Improvements in coverage of sequenced genomes will enable a more accurate and comprehensive understanding of cyanobacterial morphology, niche-adaptation, and evolution.Taxonomic studies organized the Cyanobacteria into five subsections based on morphological complexity (5). Unicellular forms are split between those that undergo solely binary fission (subsection I, Chroococcales) and those that reproduce through multiple fissions in three planes to create smaller daughter cells, baeocytes (subsection II, Pleurocapsales). Strains in subsection III (Oscillatoriales) divide the vegetative cell solely perpendicular to the growing axis. Organisms in subsections IV (Nostocales) and V (Stigonematales) are able to differentiate specific cells [i.e., heterocysts (for nitrogen fixation)] and may form akinetes (dormant cells) and hormogonia (for dispersal and symbiosis competence). Subsection V is further distinguished by the ability to form branching filaments. Before this study, two subsections (II and V) had no representative genomes, underscoring the dearth in our understanding of these more complex morphological phenotypes.In this study, 54 strains of cyanobacteria were chosen to improve the distribution of sequenced genomes. The approach is modeled on the phylogenetically driven Genomic Encyclopedia of Bacteria and Archaea (GEBA) (6), and so we refer to our data as the CyanoGEBA dataset (SI Appendix, Table S1 and Dataset S1). The results highlight the value of phylum-wide genome sequencing based on phylogenetic coverage.