scholarly journals Self-preservation strategies during bacterial biomineralization with reference to hydrozincite and implications for fossilization of bacteria

2014 ◽  
Vol 11 (100) ◽  
pp. 20140845 ◽  
Author(s):  
Bryne T. Ngwenya ◽  
Marisa Magennis ◽  
Francesca Podda ◽  
Andrei Gromov
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Laboratory Experiments ◽  
Extracellular Polymeric Substances ◽  
High Porosity ◽  
Effective Mechanism ◽  
Metabolite Exchange ◽  
Open Question ◽  
Sphere Formation

The induction of mineralization by microbes has been widely demonstrated but whether induced biomineralization leads to distinct morphologies indicative of microbial involvement remains an open question. For calcium carbonate, evidence suggests that microbial induction enhances sphere formation, but the mechanisms involved and the role of microbial surfaces are unknown. Here, we describe hydrozincite biominerals from Sardinia, Italy, which apparently start life as smooth globules on cyanobacterial filaments, and evolve to spheroidal aggregates consisting of nanoplates. Complementary laboratory experiments suggest that organic compounds are critical to produce this morphology, possibly by inducing aggregation of nanoscopic crystals or nucleation within organic globules produced by metabolizing cells. These observations suggest that production of extracellular polymeric substances by microbes may constitute an effective mechanism to enhance formation of porous spheroids that minimize cell entombment while also maintaining metabolite exchange. However, the high porosity arising from aggregation-based crystal growth probably facilitates rapid oxidation of entombed cells, reducing their potential to be fossilized.

scholarly journals Surfactin as a Green Agent Controlling the Growth of Porous Calcite Microstructures

2020 ◽  
Vol 21 (15) ◽  
pp. 5526
Author(s):  
Anna Bastrzyk ◽  
Marta Fiedot-Toboła ◽  
Halina Maniak ◽  
Izabela Polowczyk ◽  
Grażyna Płaza
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Crystal Surface ◽  
Free Calcium ◽  
Scanning Calorimetry ◽  
Green Method ◽  
Synthesis Time ◽  
Carbonate Formation ◽  
Surface Active

This study presents a new, simple way to obtain mesoporous calcite structures via a green method using an eco-friendly surface-active compound, surfactin, as a controlling agent. The effects of synthesis time and surfactin concentration were investigated. The obtained structures were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) coupled with gas mass spectrometry (QMS) analysis. The experimental data showed that surfactin molecules significantly changed the morphology of the calcite crystals, roughening and deforming the surface and creating a greater specific surface area, even at low biosurfactant concentrations (10 ppm). The size of the crystals was reduced, and the zeta potential value of calcium carbonate was more negative when more biosurfactant was added. The XRD data revealed that the biomolecules were incorporated into the crystals and slowed the transformation of vaterite into calcite. It has been shown that as long as vaterite is present in the medium, the calcite surface will be less deformed. The strong influence of surfactin molecules on the crystal growth of calcium carbonate was due to the interaction of surfactin molecules with free calcium ions in the solution as well as the biomolecules adsorption at the formed crystal surface. The role of micelles in crystal growth was examined, and the mechanism of mesoporous calcium carbonate formation was presented.

Observation and Experimentation

2018 ◽  
Author(s):  
Massimiliano Di Ventra
Keyword(s):  
Laboratory Experiments ◽  
The Difference

This chapter expands on the previous one on the role of experiments in Science. It explains the difference between observations of phenomena and controlled laboratory experiments.

scholarly journals The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charalampos Konstantinou ◽  
Yuze Wang ◽  
Giovanna Biscontin ◽  
Kenichi Soga
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Urease Activity ◽  
Coarse Sand ◽  
Carbonate Precipitation ◽  
Population Densities ◽  
Carbonate Cements ◽  
Microbially Induced Carbonate Precipitation

AbstractProtocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

scholarly journals Long non-coding RNA LINC00665 promotes gemcitabine resistance of Cholangiocarcinoma cells via regulating EMT and stemness properties through miR-424-5p/BCL9L axis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Min Lu ◽  
Xinglei Qin ◽  
Yajun Zhou ◽  
Gang Li ◽  
Zhaoyang Liu ◽  
...  
Keyword(s):  
Acquired Resistance ◽  
Transcriptional Regulators ◽  
First Line ◽  
Protein Coding ◽  
Gemcitabine Resistance ◽  
Non Coding Rna ◽  
Sphere Formation ◽  
Long Non Coding Rna ◽  
Line Chemotherapy

AbstractGemcitabine is the first-line chemotherapy drug for cholangiocarcinoma (CCA), but acquired resistance has been frequently observed in CCA patients. To search for potential long noncoding RNAs (lncRNAs) involved in gemcitabine resistance, two gemcitabine resistant CCA cell lines were established and dysregulated lncRNAs were identified by lncRNA microarray. Long intergenic non-protein coding RNA 665 (LINC00665) were found to rank the top 10 upregulated lncRNAs in our study, and high LINC00665 expression was closely associated with poor prognosis and chemoresistance of CCA patients. Silencing LINC00665 in gemcitabine resistant CCA cells impaired gemcitabine tolerance, while enforced LINC00665 expression increased gemcitabine resistance of sensitive CCA cells. The gemcitabine resistant CCA cells showed increased EMT and stemness properties, and silencing LINC00665 suppressed sphere formation, migration, invasion and expression of EMT and stemness markers. In addition, Wnt/β-Catenin signaling was activated in gemcitabine resistant CCA cells, but LINC00665 knockdown suppressed Wnt/β-Catenin activation. B-cell CLL/lymphoma 9-like (BCL9L), the nucleus transcriptional regulators of Wnt/β-Catenin signaling, plays a key role in the nucleus translocation of β-Catenin and promotes β-Catenin-dependent transcription. In our study, we found that LINC00665 regulated BCL9L expression by acting as a molecular sponge for miR-424-5p. Moreover, silencing BCL9L or miR-424-5p overexpression suppressed gemcitabine resistance, EMT, stemness and Wnt/β-Catenin activation in resistant CCA cells. In conclusion, our results disclosed the important role of LINC00665 in gemcitabine resistance of CCA cells, and provided a new biomarker or therapeutic target for CCA treament.

scholarly journals Hsa_circ_0026628 promotes the development of colorectal cancer by targeting SP1 to activate the Wnt/β-catenin pathway

2021 ◽  
Vol 12 (9) ◽  
Author(s):  
Xuexiu Zhang ◽  
Jianning Yao ◽  
Haoling Shi ◽  
Bing Gao ◽  
Haining Zhou ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Transcription Factor ◽  
Circular Rna ◽  
Luciferase Reporter ◽  
Circular Rnas ◽  
Transcriptional Level ◽  
Sp1 Transcription Factor ◽  
Reporter Assays ◽  
Sphere Formation

AbstractCircular RNAs (circRNAs) have been reported to play crucial roles in the progression of various cancers, including colorectal cancer (CRC). SP1 (Sp1 transcription factor) is a well-recognized oncogene in CRC and is deemed to trigger the Wnt/β-catenin pathway. The present study was designed to investigate the role of circRNAs which shared the same pre-mRNA with SP1 in CRC cells. We identified that hsa_circ_0026628 (circ_0026628), a circular RNA that originated from SP1 pre-mRNA, was upregulated in CRC cells. Sanger sequencing and agarose gel electrophoresis verified the circular characteristic of circ_0026628. Functional assays including CCK-8, colony formation, transwell, immunofluorescence staining, and sphere formation assay revealed the function of circ_0026628. RNA pull-down and mass spectrometry disclosed the proteins interacting with circ_0026628. Mechanistic assays including RIP, RNA pull-down, CoIP, ChIP, and luciferase reporter assays demonstrated the interplays between molecules. The results depicted that circ_0026628 functioned as a contributor to CRC cell proliferation, migration, EMT, and stemness. Mechanistically, circ_0026628 served as the endogenous sponge of miR-346 and FUS to elevate SP1 expression at the post-transcriptional level, thus strengthening the interaction between SP1 and β-catenin to activate the Wnt/β-catenin pathway. In turn, the downstream gene of Wnt/β-catenin signaling, SOX2 (SRY-box transcription factor 2), transcriptionally activated SP1 and therefore boosted circ_0026628 level. On the whole, SOX2-induced circ_0026628 sponged miR-346 and recruited FUS protein to augment SP1, triggering the downstream Wnt/β-catenin pathway to facilitate CRC progression.

How much would you like to pay? Trust, reciprocity and prosocial motivations in El trato

2012 ◽  
Vol 51 (3) ◽  
pp. 389-417 ◽  
Author(s):  
Francisco J León ◽  
José A Noguera ◽  
Jordi Tena-Sánchez
Keyword(s):  
Social Science ◽  
External Validity ◽  
Laboratory Experiments ◽  
Social Science Research ◽  
Science Research ◽  
Trust Game ◽  
Sales Strategy ◽  
Pay What You Want ◽  
Natural Settings

Prosocial motivations and reciprocity are becoming increasingly important in social-science research. While laboratory experiments have challenged the assumption of universal selfishness, the external validity of these results has not been sufficiently tested in natural settings. In this article we examine the role of prosocial motivations and reciprocity in a Pay What You Want (PWYW) sales strategy, in which consumers voluntarily decide how much to pay for a product or service. This article empirically analyses the only PWYW example in Spain to date: the El trato (‘The deal’) campaign launched by the travel company Atrápalo, which offered different holiday packages under PWYW conditions in July 2009. Our analysis shows that, although the majority of the customers did not behave in a purely self-interested manner, they nonetheless did so in a much higher proportion than observed in similar studies. We present different hypotheses about the mechanisms that may explain these findings. Specifically, we highlight the role of two plausible explanations: the framing of the campaign and the attribution of ‘hidden’ preferences to Atrápalo by its customers, which undermined the interpretation of El trato as a trust game.

The Effect of Face Consciousness on Consumption of Counterfeit Luxury Goods

2014 ◽  
Vol 42 (6) ◽  
pp. 1007-1014 ◽  
Author(s):  
Yun-Qing Chen ◽  
Hong Zhu ◽  
Meng Le ◽  
Yi-Zhen Wu
Keyword(s):  
Purchase Intention ◽  
Laboratory Experiments ◽  
Positive Influence ◽  
Luxury Goods ◽  
Intention To Purchase ◽  
Luxury Item ◽  
Moderating Role ◽  
Chinese Undergraduates ◽  
Significant Positive Influence

We conducted 3 laboratory experiments to determine how face consciousness influences consumption of counterfeit luxury goods, along with the moderating roles of usage occasion and brand prominence. The participants in the first study were 138 Chinese undergraduates who were allocated to a 2 × 2 design to evaluate their intention to purchase a counterfeit luxury item that would be used either in public or in private. In Studies 2 and 3, using two 2 × 2 designs we evaluated the purchase intention of the participants (132 and 136, respectively) in order to investigate the moderating role of brand prominence. The results showed that participants' face consciousness had a significant positive influence on intention to purchase counterfeit luxury goods. In addition, the products' usage occasion and brand prominence positively moderated the influence that face consciousness had on counterfeit luxury item purchase intention of our participant groups.

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