Clinanthus microstephium,an Amaryllidaceae Species with Cholinesterase Inhibitor Alkaloids: Structure−Activity Analysis of Haemanthamine Skeleton Derivatives

Plants of the Amaryllidaceae family are well‐known (not only) for their ornamental value but also for the alkaloids that they produce. In this report, the first phytochemical study of Clinanthus genus was carried out. The chemical composition of alkaloid fractions from Clinanthus microstephium was analyzed by GC/MS and NMR. Seven known compounds belonging to three structural types of Amaryllidaceae alkaloids were identified. An epimeric mixture of a haemanthamine‐type compound (6‐hydroxymaritidine) was tested as an inhibitor against acetyl‐ and butyrylcholinesterase enzymes (AChE and BChE, respectively), two enzymes relevant in the treatment of Alzheimer's disease, with good results. Structure–activity relationships through molecular docking studies with this alkaloid and other structurally related compounds were discussed.     

Drastic changes in aquatic bacterial populations from the Cuatro Cienegas Basin (Mexico) in response to long-term environmental stress

Understanding the changes of aquatic microbial community composition in response to changes in temperature and ultraviolet irradiation is relevant for predicting biogeochemical modifications in the functioning of natural microbial communities under global climate change scenarios. Herein we investigate shifts in the bacterioplankton composition in response to long-term changes in temperature and UV radiation. For this purpose, 15 mesocosms were seeded with composite aquatic microbial communities from natural pools within the Cuatro Cienegas Basin (Mexican Chihuahuan desert) and were subject to different temperatures and UV conditions. 16S rRNA gene clone libraries were obtained from water samples at the mid-point (4 months) and the end of the experiment (8 months). An increase in bacterial diversity over time was found in the treatment of constant temperature and UV protection, which suggests that stable environments promote the establishment of complex and diverse bacterial community. Drastic changes in the phylogenetic bacterioplankton composition and structure were observed in response to fluctuating temperature and increasing UV radiation and temperature. Fluctuating temperature induced the largest decrease of bacterial richness during the experiment, indicating that frequent temperature changes drive the reduction in abundance of several species, most notably autotrophs. The long-term impact of these environmental stresses reduced diversity and selected for generalist aquatic bacterial populations, such as Porphyrobacter. These changes at the community level occur at an ecological time scale, suggesting that under global warming scenarios cascade effects on the food web are possible if the microbial diversity is modified.     

Rvs161p Interacts with Fus2p to Promote Cell Fusion in Saccharomyces cerevisiae

FUS7 was previously identified by a mutation that causes a defect in cell fusion in a screen for bilateral mating defects. Here we show that FUS7 is allelic to RVS161/END6, a gene implicated in a variety of processes including viability after starvation, endocytosis, and actin cytoskeletal organization. Two lines of evidence indicate that RVS161/END6's endocytic function is not required for cell fusion. First, several other endocytic mutants showed no cell fusion defects. Second, we isolated five function-specific alleles of RVS161/FUS7 that were defective for endocytosis, but not mating, and three alleles that were defective for cell fusion but not endocytosis. The organization of the actin cytoskeleton was normal in the cell fusion mutants, indicating that Rvs161p's function in cell fusion is independent of actin organization. The three to fourfold induction of RVS161 by mating pheromone and the localization of Rvs161p-GFP to the cell fusion zone suggested that Rvs161p plays a direct role in cell fusion. The phenotypes of double mutants, the coprecipitation of Rvs161p and Fus2p, and the fact that the stability of Fus2p was strongly dependent on Rvs161p's mating function lead to the conclusion that Rvs161p is required to interact with Fus2p for efficient cell fusion.     

8-Oxoguanine DNA-glycosylase repair activity and expression: a comparison between cryopreserved isolated lymphocytes and EBV-derived lymphoblastoid cell lines

Several lines of evidence suggest an association between oxidative DNA-damage repair capacity and cancer risk. In particular, a DNA-glycosylase assay for removal of 8-oxoguanine (8-oxoG) in peripheral blood mononuclear cells (PBMC) has been successfully applied to identify populations with increased risk for lung cancer and squamous cell carcinomas of head and neck. In order to verify whether EBV-transformed lymphoblastoid cell lines (LCL) are a suitable surrogate for PBMC in specific DNA-repair phenotypic assays, a validation trial was conducted. PBMC from 20 healthy subjects were collected and an aliquot was transformed with EBV to obtain LCL. The ability of cell-free extracts from both cell types to incise a 3'-fluorescently labelled duplex oligonucleotide containing a single 8-oxoG (OGG assay) was evaluated. Since this activity is mediated predominantly by OGG1, the OGG1 gene expression was also measured. 8-oxoG DNA-glycosylase activity and OGG1 expression were significantly higher (p<0.0001) in LCL than in PBMC. However, while this assay was shown to be robust and reproducible when used on PBMC (intra-assay CV=8%), a high intra-culture variability was observed with LCL (intra-culture CV=16.8%). Neither differences on OGG1 gene expression nor the cell-cycle distribution seemed to account for this variability. Inter-individual variability of OGG activity in PBMC and LCL was not associated with OGG1 gene expression. We have therefore established a non-radioactive cleavage assay that can be easily applied to measure OGG activity in human PBMC. The use of LCL for DNA-repair genotype-phenotype correlation studies seems to be inappropriate, at least with cell-free based functional assays.     

The Expression of Connexins and SOX2 Reflects the Plasticity of Glioma Stem-Like Cells

Glioblastoma (GBM) is the most malignant primary brain tumor, with an average survival rate of 15 months. GBM is highly refractory to therapy, and such unresponsiveness is due, primarily, but not exclusively, to the glioma stem-like cells (GSCs). This subpopulation express stem-like cell markers and is responsible for the heterogeneity of GBM, generating multiple differentiated cell phenotypes. However, how GBMs maintain the balance between stem and non-stem populations is still poorly understood. We investigated the GBM ability to interconvert between stem and non-stem states through the evaluation of the expression of specific stem cell markers as well as cell communication proteins. We evaluated the molecular and phenotypic characteristics of GSCs derived from differentiated GBM cell lines by comparing their stem-like cell properties and expression of connexins. We showed that non-GSCs as well as GSCs can undergo successive cycles of gain and loss of stem properties, demonstrating a bidirectional cellular plasticity model that is accompanied by changes on connexins expression. Our findings indicate that the interconversion between non-GSCs and GSCs can be modulated by extracellular factors culminating on differential expression of stem-like cell markers and cell-cell communication proteins. Ultimately, we observed that stem markers are mostly expressed on GBMs rather than on low-grade astrocytomas, suggesting that the presence of GSCs is a feature of high-grade gliomas. Together, our data demonstrate the utmost importance of the understanding of stem cell plasticity properties in a way to a step closer to new strategic approaches to potentially eliminate GSCs and, hopefully, prevent tumor recurrence.     

Economic Decisions for Others: An Exception to Loss Aversion Law

In everyday life, people often make decisions on behalf of others. The current study investigates whether risk preferences of decision-makers differ when the reference point is no longer their own money but somebody else money. Thirty four healthy participants performed three different monetary risky choices tasks by making decisions for oneself and for another unknown person. Results showed that loss aversion bias was significantly reduced when participants were choosing on behalf of another person compared to when choosing for themselves. The influence of emotions like regret on decision-making may explain these results. We discuss the importance of the sense of responsibility embodied in the emotion of regret in modulating economic decisions for self but not for others. Moreover, our findings are consistent with the Risk-as-feelings hypothesis, suggesting that self-other asymmetrical behavior is due to the extent the decision-maker is affected by the real and emotional consequences of his/her decision.     

Nusinersen treatment and cerebrospinal fluid neurofilaments: An explorative study on Spinal Muscular Atrophy type 3 patients

The antisense oligonucleotide Nusinersen has been recently licensed to treat spinal muscular atrophy (SMA). Since SMA type 3 is characterized by variable phenotype and milder progression, biomarkers of early treatment response are urgently needed. We investigated the cerebrospinal fluid (CSF) concentration of neurofilaments in SMA type 3 patients treated with Nusinersen as a potential biomarker of treatment efficacy. The concentration of phosphorylated neurofilaments heavy chain (pNfH) and light chain (NfL) in the CSF of SMA type 3 patients was evaluated before and after six months since the first Nusinersen administration, performed with commercially available enzyme-linked immunosorbent assay (ELISA) kits. Clinical evaluation of SMA patients was performed with standardized motor function scales. Baseline neurofilament levels in patients were comparable to controls, but significantly decreased after six months of treatment, while motor functions were only marginally ameliorated. No significant correlation was observed between the change in motor functions and that of neurofilaments over time. The reduction of neurofilament levels suggests a possible early biochemical effect of treatment on axonal degeneration, which may precede changes in motor performance. Our study mandates further investigations to assess neurofilaments as a marker of treatment response.     

Investigation of Ixodid ticks as vectors of Babesia caballi and Theileria equi (Protozoa: Apicomplexa) in central Italy

Babesia caballi and Theileria equi are widely recognized as causative agents of equine pirolasmosis (EP), an acute, sub‐acute, and chronic disease of equines, with relevant economic impact on horse trade worldwide. Although several studies on EP prevalence from central Italy have been published, data on ticks responsible for its transmission are still lacking. In this study, we identified a potential competent vector, investigating main features of its ecology together with EP infection rates. A two‐year sampling of questing ticks was carried out for the first time in Italy in an area known for high EP prevalence in horse sera, detecting the association between Rhipicephalus bursa and causative agents of EP. Most of the positive pools harbored a single infection (91.1%); mixed infections were also detected (8.9%). The infection rate for T. equi slightly decreased among years; B. caballi showed a lower, but increasing, infection rate. Tick phenology, climate variables, and peaks of EP prevalence indicated late May and second half of June as periods with the highest risk of new infections, especially during warm and dry days.