MICP mediated by indigenous bacteria isolated from tailings for biocementation for reduction of wind erosion.

In this study, native ureolytic bacteria were isolated from copper tailings soils to perform microbial-induced carbonate precipitation (MICP) tests and evaluate their potential for biocement formation and their contribution to reduce the dispersion of particulate matter into the environment from tailings containing potentially toxic elements. It was possible to isolate a total of 46 bacteria; among them only three showed ureolytic activity: Priestia megaterium T130-1, Paenibacillus sp. T130-13 and Staphylococcus sp. T130-14. Biocement cores were made by mixing tailings with the isolated bacteria in presence of urea, resulting similar to those obtained with Sporosarcina pasteurii and Bacillus subtilis used as positive control. Indeed, XRD analysis conducted on biocement showed the presence of microcline (B. subtilis 17%; P. megaterium 11. 9%), clinochlore (S. pasteurii, 6.9%) and magnesiumhornblende (Paenibacillus sp. 17.8%; P. megaterium 14.6%); all these compounds were not initially present in the tailings soils. Moreover the presence of calcite (control 0.828%; Paenibacillus sp. 5.4%) and hematite (control 0.989%; B. subtilis 6.4%) was also significant unlike the untreated control. The development of biofilms containing abundant amount of Ca, C, and O on microscopic soil particles was evidenced by means of FE-SEM-EDX and XRD. Wind tunnel tests were carried out to investigate the resistance of biocement samples, accounted for a mass loss five holds lower than the control, i.e., the rate of wind erosion in the control corresponded to 82 g/m2h while for the biocement treated with Paenibacillus sp. it corresponded to only 16.371 g/m2h. Finally, in compression tests, the biocement samples prepared with P. megaterium (28.578 psi) and Paenibacillus sp. (28.404 psi) showed values similar to those obtained with S. pasteurii (27.102 psi), but significantly higher if compared to the control (15.427 psi), thus improving the compression resistance capacity of the samples by 85.2% and 84.1% with respect to the control. According to the results obtained, the biocement samples generated with the native strains showed improvements in the mechanical properties of the soil supporting them as potential candidates in applications for the stabilization of mining liabilities in open environments using bioaugmentation strategies with native strains isolated from the same mine tailing.

Activation of Transposable Elements in Human Skeletal Muscle Fibers upon Statin Treatment.

High cholesterol levels have been linked to a high risk of cardiovascular diseases, and preventative pharmacological care to lower cholesterol levels is critically important. Statins, which are hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, are drugs used to reduce the endogenous cholesterol synthesis, thus minimizing its pathophysiological effects. Despite the proven benefits, statins therapy is known to cause a number of skeletal muscle disorders, including myalgia, myopathy and myositis. The mechanisms underlying such statin-induced side effects are unknown. Recently, a group of genes and molecular pathways has been described to participate in statin-induced myopathy, caused by either simvastatin or rosuvastatin, although the mechanism by which changes in gene regulation occur was not studied. Transposable Elements (TEs), repetitive elements that move within the genome, are known to play regulatory roles in gene expression; however, their role in statin-induced muscle damage has not been studied. We analyzed the expression of TEs in human skeletal fiber cells treated with either simvastatin or rosuvastatin, as well as their respective controls, and identified TEs that change their expression in response to the treatment. We found that simvastatin resulted in >1000 differentially expressed (DE) TEs, whereas rosuvastatin resulted in only 27 DE TEs. Using network analysis tools, we predicted the impact of the DE TEs on the expression of genes and found that amongst the genes potentially modulated by TEs, there are some previously associated to statin-linked myopathy pathways (e.g., AKT3). Overall, our results indicate that TEs may be a key player in the statin-induced muscle side effects.

Response to Static Magnetic Field-Induced Stress in Scenedesmus obliquus and Nannochloropsis gaditana.

Magnetic fields in biological systems is a promising research field; however, their application for microalgae has not been fully exploited. This work aims to measure the enzymatic activity and non-enzymatic activity of two microalgae species in terms of superoxide dismutase (SOD), catalase (CAT), and carotenoids, respectively, in response to static magnetic fields-induced stress. Two magnet configurations (north and south) and two exposure modes (continuous and pulse) were applied. Two microalgae species were considered, the Scenedesmus obliquus and Nannochloropsis gaditana. The SOD activity increased by up to 60% in S. obliquus under continuous exposure. This trend was also found for CAT in the continuous mode. Conversely, under the pulse mode, its response was hampered as the SOD and CAT were reduced. For N. gaditana, SOD increased by up to 62% with the south configuration under continuous exposure. In terms of CAT, there was a higher activity of up to 19%. Under the pulsed exposure, SOD activity was up to 115%. The CAT in this microalga was increased by up to 29%. For N. gaditana, a significant increase of over 40% in violaxanthin production was obtained compared to the control, when the microalgae were exposed to SMF as a pulse. Depending on the exposure mode and species, this methodology can be used to produce oxidative stress and obtain an inhibitory or enhanced response in addition to the significant increase in the production of antioxidant pigments.

Role of Nhp6 and Hmo1 in SWI/SNF occupancy and nucleosome landscape at gene regulatory regions.

Diverse chromatin modifiers are involved in regulation of gene expression at the level of transcriptional regulation. Among these modifiers are ATP-dependent chromatin remodelers, where the SWI/SNF complex is the founding member. It has been observed that High Mobility Group (HMG) proteins can influence the activity of a number of these chromatin remodelers. In this context, we have previously demonstrated that the yeast HMG proteins Nhp6 and Hmo1 can stimulate SWI/SNF activity. Here, we studied the genome-wide binding patterns of Nhp6, Hmo1 and the SWI/SNF complex, finding that most of gene promoters presenting high occupancy of this complex also display high enrichment of these HMG proteins. Using deletion mutant strains we demonstrate that binding of SWI/SNF is significantly reduced at numerous genomic locations by deletion of NHP6 and/or deletion of HMO1. Moreover, alterations in the nucleosome landscape take place at gene promoters undergoing reduced SWI/SNF binding. Additional analyses show that these effects also correlate with alterations in transcriptional activity. Our results suggest that, besides the ability to stimulate SWI/SNF activity, these HMG proteins are able to assist the loading of this complex onto gene regulatory regions.

Expression profiles of the Gα subunits during Xenopus tropicalis embryonic development.

Heterotrimeric G protein signaling plays major roles during different cellular events. However, there is a limited understanding of the molecular mechanisms underlying G protein control during embryogenesis. G proteins are highly conserved and can be grouped into four subfamilies according to sequence homology and function. To further studies on G protein function during embryogenesis, the present analysis identified four Gα subunits representative of the different subfamilies and determined their spatiotemporal expression patterns during Xenopus tropicalis embryogenesis. Each of the Gα subunit transcripts was maternally and zygotically expressed, and, as development progressed, dynamic expression patterns were observed. In the early developmental stages, the Gα subunits were expressed in the animal hemisphere and dorsal marginal zone. While expression was observed at the somite boundaries, in vascular structures, in the eye, and in the otic vesicle during the later stages, expression was mainly found in neural tissues, such as the neural tube and, especially, in the cephalic vesicles, neural crest region, and neural crest-derived structures. Together, these results support the pleiotropism and complexity of G protein subfamily functions in different cellular events. The present study constitutes the most comprehensive description to date of the spatiotemporal expression patterns of Gα subunits during vertebrate development.

The CREB Transcription Factor Controls Transcriptional Activity of the Human RIC8B Gene.

Proper regulation of gene expression is essential for normal development, cellular growth, and differentiation. Differential expression profiles of mRNA coding for vertebrate Ric-8B during embryo and adult stages have been observed. In addition, Ric-8B is expressed in few cerebral nuclei subareas. These facts point to a dynamic control of RIC8B gene expression. In order to understand the transcriptional regulation of this gene, we searched for cis-elements in the sequence of the human RIC8B promoter region, identifying binding sites for the basic/leucine zipper (bZip) CREB transcription factor family (CRE sites) and C/EBP transcription factor family (C/EBP sites). CRE sites were found clustered near the transcription start site, while the C/EBP sites were found clustered at around 300 bp upstream the CRE sites. Here, we demonstrate the ability of CREB1 and C/EBPß to bind their respective elements identified in the RIC8B promoter. Comparative protein-DNA interaction analyses revealed only the proximal elements as high affinity sites for CREB1 and only the distal elements as high affinity sites for C/EBPß. Chromatin immunoprecipitation analyses, carried out using a human neuroblastoma cell line, confirmed the preferential association of CREB to the proximal region of the RIC8B promoter. By performing luciferase reporter assays, we found the CRE sites as the most relevant elements for its transcriptional activity. Taken together, these data show the existence of functional CREB and C/EBP binding sites in the human RIC8B gene promoter, a particular distribution of these sites and demonstrate a relevant role of CREB in stimulating transcriptional activity of this gene. J. Cell. Biochem. 117: 1797-1805, 2016. © 2016 Wiley Periodicals, Inc.