Simvastatin rises reactive oxygen species levels and induces senescence in human melanoma cells by activation of p53/p21 pathway

Recent studies demonstrated that simvastatin has antitumor properties in several types of cancer cells, mainly by inducing apoptosis and inhibiting growth. The arrest of proliferation is a feature of cellular senescence; however, the occurrence of senescence in melanoma cells upon simvastatin treatment has not been investigated until now. Our results demonstrated that exposure of human metastatic melanoma cells (WM9) to simvastatin induces a senescent phenotype, characterized by G1 arrest, positive staining for senescence-associated β-galactosidase assay, and morphological changes. Also, the main pathways leading to cell senescence were examined in simvastatin-treated human melanoma cells, and the expression levels of phospho-p53 and p21 were upregulated by simvastatin, suggesting that cell cycle regulators and DNA damage pathways are involved in the onset of senescence. Since simvastatin can act as a pro-oxidant agent, and oxidative stress may be related to senescence, we measured the intracellular ROS levels in WM9 cells upon simvastatin treatment. Interestingly, we found an increased amount of intracellular ROS in these cells, which was accompanied by elevated expression of catalase and peroxiredoxin-1. Collectively, our results demonstrated that simvastatin can induce senescence in human melanoma cells by activation of p53/p21 pathway, and that oxidative stress may be related to this process.     

Microhabitat Variation Explains Local‐scale Distribution of Terrestrial Amazonian Lizards in Rondônia,Western Brazil

We investigate the role of ecology and phylogeny in the association between lizard abundance and microhabitat variables in an Amazon rain forest site. Using pitfall trap arrays, we collected data from 349 individuals belonging to 23 lizard species. After accounting for spatial autocorrelation and using a canonical correspondence analysis (CCA), we found that lizard captures were significantly associated with microhabitat variables, which accounted for 48 percent of the observed variation. Furthermore, a canonical phylogenetic ordination (CPO) indicated that microhabitat variables are more important in determining the distribution of lizard species than phylogenetic relationships among species. Termite nests, canopy openness, and tree circumference were strongly associated with the number of captures of certain lizard species. Our results confirm autecology studies of individual lizard species for which data are available. We suggest that maintaining heterogeneous forested microhabitats should be a central goal for sustaining a high lizard biodiversity in Amazon rain forests.     

Pollen consumed by the solitary bee Tetrapedia diversipes (Apidae: Tetrapediini) in a tropical agroecosystem

Pollen analysis of the larval food supply is an important tool for identifying the plants that provide the floral resources used by bees. The present study documents the pollen sources consumed by larvae of the solitary bee Tetrapedia diversipes in a tropical agroecosystem. A total of 60 pollen types were recorded with three families being the most important. Euphorbiaceae (60.5%), Malpighiaceae (16.8%) and Asteraceae (12.2%) pollen had the greatest representation in the samples examined. The pollen of Dalechampia dioscoreifolia predominated in the diet of the larvae of T. diversipes (RF?=?56.35%) and indicates the importance of this plant in maintaining populations of this solitary bee.     

Diversity and expression of P450 genes from Dendroctonus valens LeConte (Curculionidae: Scolytinae) in response to different kairomones

Bark beetles (Curculionidae: Scolytinae) are major cause of woody plants death in the world. They colonize the stem and other parts of trees recognizing host-produced specific compounds (kairomones) and insect pheromones. Bark beetle's antennae and alimentary canal participate in the host selection identifying chemical compounds produced by trees and insects, and also in the metabolism and detoxification of these compounds. The red turpentine beetle (RTB), Dendroctonus valens LeConte, is an unaggressive species that colonize > 40 pine species (Pinaceae) in North and Central America. Several studies suggest that bark beetle cytochrome P450 enzymes are involved in monoterpene oxidation. In this study we identified by means of PCR, cloning, sequencing, and bioinformatic analysis, eleven full-length genes: five CYP4, four CYP6, and two CYP9 in the antennae and gut region of RTB, after stimulation with vapors of monoterpenes: (±)-α-pinene, (R)-(+)-α-pinene, (S)-(?)-β-pinene, (S)-(?)-α-pinene and (+)-3-carene; pine trees volatiles used by RTB as kairomones. The recovered cDNA of these genes vary from 1.5 kb to 1.8 kb and the open frame encodes from 496 to 562 amino acid proteins. The bioinformatic analysis suggests that the majority of P450 proteins encoded by these genes are membrane anchored in the endoplasmic reticulum. RT-qPCR assays showed differential expression of all CYP genes between male and female. The gene expression was dependent of monoterpenes and exposure time, with some of them sex, antennae and gut region specific. Significant differences among monoterpenes, gut region, antennae and exposure time were found. Our results suggest that some of these genes may be involved in the detoxification process of these compounds during tree colonization.     

Algistatic effect of a quinonamethide triterpene on Microcystis novacekii

Cyanobacteria proliferation represents a problem to water treatment for human consumption supply. Species of the genus Microcystis, commonly found in continental waters, can bloom and produce microcystine and other toxic compounds associated to human and animal poisoning, depending on the nutrient levels present in the water. The use of natural products to control cyanobacteria blooms is promising since they are less harmful to the environment than compounds obtained by organic syntheses. Triterpenes, which are associated with several biological activities, have been isolated from species of the genus Maytenus (Celastraceae), commonly found in Cerrado regions of Brazil. Tingenone is a pentacyclic triterpene that has cytotoxic properties and induces growth inhibition in some microorganisms. In this study, the effects of tingenone isolated from Maytenus gonoclada at distinct concentrations (e.g., 50, 150, 500, 1,500, and 4,500 μg? L^?1) on the growth rates of Microcystis novacekii was investigated. The algicide activity was verified using M. novacekii cultures growing in ASM1 culture medium at 23 °C and continuous illumination for 96 h. Growth inhibition was monitored by light microscopy and optical density (OD_680 nm). The median effective concentration associated to the M. novacekii inhibition growth induced by tingenone was 12.2 μg? L^?1. The result indicates that tingenone has algicide effect and can be potentially applied in water management for public supply, replacing synthetic algicides.     

Temperature alters interspecific relationships among aquatic fungi

Temperature is a key factor in determining the structure and performance of fungal assemblages on decomposing plant litter in streams. However, little is known of how temperature affects interspecific relationships among fungi. We compared the growth of four aquatic hyphomycetes co-occurring in temperate streams, in monocultures and all species combinations when exposed to five temperatures from 11 to 27 °C. In monocultures, maximum growth rates of Heliscus submersus, Lunulospora curvula and Varicosporium elodeae occurred at 27 °C whereas Articulospora tetracladia had the lowest growth rate. At 27 °C, the increase in species diversity had no effect on the growth of V. elodeae, increased the growth of H. submersus and L. curvula, and decreased the growth of A. tetracladia. Results suggest that within a species' optimal temperature range the growth of that species increases with higher fungal diversity, while outside this range growth decreases with diversity.     

Inhibition of Histone Deacetylase Impacts Cancer Stem Cells and Induces Epithelial-Mesenchyme Transition of Head and Neck Cancer

The genome is organized and packed into the nucleus through interactions with core histone proteins. Emerging evidence suggests that tumors are highly responsive to epigenetic alterations that induce chromatin-based events and dynamically influence tumor behavior. We examined chromatin organization in head and neck squamous cell carcinoma (HNSCC) using acetylation levels of histone 3 as a marker of chromatin compaction. Compared to control oral keratinocytes, we found that HNSCC cells are hypoacetylated and that microenvironmental cues (e.g., microvasculature endothelial cells) induce tumor acetylation. Furthermore, we found that chemical inhibition of histone deacetylases (HDAC) reduces the number of cancer stem cells (CSC) and inhibits clonogenic sphere formation. Paradoxically, inhibition of HDAC also induced epithelial-mesenchymal transition (EMT) in HNSCC cells, accumulation of BMI-1, an oncogene associated with tumor aggressiveness, and expression of the vimentin mesenchymal marker. Importantly, we observed co-expression of vimentin and acetylated histone 3 at the invasion front of human HNSCC tumor tissues. Collectively, these findings suggest that environmental cues, such as endothelial cell-secreted factors, modulate tumor plasticity by limiting the population of CSC and inducing EMT. Therefore, inhibition of HDAC may constitute a novel strategy to disrupt the population of CSC in head and neck tumors to create a homogeneous population of cancer cells with biologically defined signatures and predictable behavior.     

Agrobacterium-mediated transformation of Guignardia citricarpa: An efficient tool to gene transfer and random mutagenesis

Guignardia citricarpa is the causal agent of Citrus Black Spot (CBS), an important disease in Citriculture. Due to the expressive value of this activity worldwide, especially in Brazil, understanding more about the functioning of this fungus is of utmost relevance, making possible the elucidation of its infection mechanisms, and providing tools to control CBS. This work describes for the first time an efficient and successful methodology for genetic transformation of G. citricarpa mycelia, which generated transformants expressing the gene encoding for the gfp (green fluorescent protein) and also their interaction with citrus plant. Mycelia of G. citricarpa were transformed via Agrobacterium tumefaciens, which carried the plasmid pFAT-gfp, contains the genes for hygromycin resistance (hph) as well as gfp. The optimization of the agrotransformation protocol was performed testing different conditions (type of membrane; inductor agent concentration [acetosyringone – AS] and cocultivation time). Results demonstrated that the best condition occurred with the utilization of cellulose's ester membrane; 200 μM of AS and 96 h as cocultivation time. High mitotic stability (82 %) was displayed by transformants using Polymerase Chain Reaction (PCR) technique to confirm the hph gene insertion. In addition, the presence of gfp was observed inside mycelia by epifluorescence optical microscopy. This technique easy visualization of the behaviour of the pathogen interacting with the plant for the first time, allowing future studies on the pathogenesis of this fungus. The establishment of a transformation method for G. citricarpa opens a range of possibilities and facilitates the study of insertional mutagenesis and genetic knockouts, in order to identify the most important genes involved in the pathogenesis mechanisms and plant–pathogen interaction.     

Apoptosis through Bcl-2/Bax and Cleaved Caspase Up-Regulation in Melanoma Treated by Boron Neutron Capture Therapy

Boron neutron capture therapy (BNCT) is a binary treatment involving selective accumulation of boron carriers in a tumor followed by irradiation with a thermal or epithermal neutron beam. The neutron capture reaction with a boron-10 nucleus yields high linear energy transfer (LET) particles, alpha and ⁷Li, with a range of 5 to 9 µm. These particles can only travel very short distances and release their damaging energy directly into the cells containing the boron compound. We aimed to evaluate proliferation, apoptosis and extracellular matrix (ECM) modifications of B16F10 melanoma and normal human melanocytes after BNCT. The amounts of soluble collagen and Hsp47, indicating collagen synthesis in the ECM, as well as the cellular markers of apoptosis, were investigated. BNCT decreased proliferation, altered the ECM by decreasing collagen synthesis and induced apoptosis by regulating Bcl-2/Bax in melanoma. Additionally, BNCT also increased the levels of TNF receptor and the cleaved caspases 3, 7, 8 and 9 in melanoma. These results suggest that multiple pathways related to cell death and cell cycle arrest are involved in the treatment of melanoma by BNCT.     

Parathyroidectomy Improves Survival In Patients with Severe Hyperparathyroidism: A Comparative Study

Background and objectives

Secondary hyperparathyroidism (SHPT) in CKD is associated with an increased risk for mortality, but definitive data showing that parathormone control decreases mortality is still lacking. This study aimed to compare the mortality of patients with severe SHPT submitted to parathyroidectomy(PTX) with those who did not have access to surgery.

Methods

This is a retrospective study in a cohort of 251 CKD patients with severe SHPT who were referred to a CKD-MBD Center for PTX from 2005 until 2012.

Results

Most of our patients had indication of PTX, but only 49% of them had access to this surgical procedure. After a mean follow-up of 23 months, 72 patients had died. Non-survivors were older; more often had diabetes, lower serum 25 vitamin D and mostly had not been submitted to surgery. The relative risk of death was lower in the PTX patients (0.428; 95% CI, 0.28 to 0.67; p<0.0001). After adjustments, mortality risk was dependent on age (1.04; 95% CI, 1.01 to 1.07; p = 0.002), 25 vitamin D (0.43; 95% CI, 0.24 to 0.81; p = 0.006) and no access to PTX (4.13; 95% CI, 2.16 to 7.88; p<0.0001). Results remained the same in a second model using the PTX date as the study start date for the PTX group.

Conclusions

Our data confirms the benefit of PTX on mortality in patients with severe SHPT. The high mortality encountered in our population is significant and urges the need to better treat these patients.