IMPACT OF PHYSICO-CHEMICAL PROPERTIES OF MANUFACTURED NANOMATERIALS ON PLANT UPTAKE AND TROPHIC TRANSFER

Large quantities of manufactured nanomaterials (MNM) are released into the environment by human activity each year. The entry of MNM into the terrestrial food webs, which has the potential for far-reaching impacts, begins with the uptake by plant species from the soil. These processes can be affected by MNM physico-chemical properties such as size, chemical composition, surface charge, etc., of which our knowledge is still incomplete. To bridge some of the gaps in our understanding of these processes and, specifically, to determine whether the physico-chemical properties of the MNM are predictive of their behavior in terrestrial food chains, we conducted a series of experiments using different MNM and model organisms. First, we synthesized functionalized CeO2 MNM having different charges and exposed tomato plants (Solanum lycopersicum cv Micro-Tom) to them. We found that plant growth and the rate of root-to-shoot translocation were functions of surface charge and exposure concentration. Mechanisms of entry into roots were examined using recent advances in high-resolution synchrotron X-ray microscopy to show that a combination of apoplastic and symplastic routes was used by the particles to penetrate to the interior of the roots. Our results also illustrate that these particles have drastically different tissue distribution patterns depending on their surface charges. Second, we exposed tomato plants with these CeO2 MNM and fed the leaves to the tobacco hornworm (Manduca sexta). Differential trophic transfer was observed as a function of the surface charge of the particles. An uptake and elimination study was conducted to obtain a time course of Ce dynamics. Despite no observed overall biomagnification across trophic levels, these differentially charged CeO2 MNMs had higher bioaccumulation factors than that of ionic Ce3+. The uptake-elimination dynamics were influenced by the surface charge of the NPs. Positively charged NPs had higher bioaccumulation factors and assimilation efficiencies but lower elimination rate than neutral and negatively charged CeO2 MNMs. Finally, to determine if studies conducted with highly purified, lab synthesized materials, were predictive of behavior of commercial nanopesticide formulations, we studied the dietary uptake of Cu(OH)2 MNMs by hornworms feeding on surface-contaminated tomato leaves. We compared lab-synthesized copper hydroxide (Cu(OH)2) nanowire with the widely used fungicide KOCIDE® 3000, whose active ingredient is nano-needles of copper hydroxide (Cu(OH)2). The difference in their toxicity and accumulation/elimination dynamics was found to correlate with the solubility of the materials. We have shown that the physico-chemical properties of MNM affect the toxicity, bio-distribution and trophic transfer of MNM in terrestrial ecosystems. With the increase of MNM release into the environment as a result of the rapid development of nanotechnology, these results have important implications for the evaluation of environmental risks associated with these MNMs and may help the application of nanotechnology to evolve to be more environmentally friendly

Glycolytic Reprogramming Through PCK2 Regulates Tumor Initiation of Prostate Cancer Cells

Tumor-initiating cells (TICs) play important roles in tumor progression and metastasis. Identifying the factors regulating TICs may open new avenues in cancer therapy. Here, we show that TIC-enriched prostate cancer cell clones use more glucose and secrete more lactate than TIC-low clones. We determined that elevated levels of phosphoenolpyruvate carboxykinase isoform 2 (PCK2) are critical for the metabolic switch and the maintenance of TICs in prostate cancer. Information from prostate cancer patient databases revealed that higher PCK2 levels correlated with more aggressive tumors and lower survival rates. PCK2 knockdown resulted in low TIC numbers, increased cytosolic acetyl-CoA and cellular protein acetylation. Our data suggest PCK2 promotes tumor initiation by lowering acetyl-CoA level through reducing the mitochondrial tricarboxylic acid (TCA) cycle. Thus, PCK2 is a potential therapeutic target for aggressive prostate tumors

An Experimental Study of Within- and Cross-cultural Cooperation: Chinese and American Play in the Prisoner’s Dilemma Game

We study whether cross- and within-culture groups have different cooperation rates in the Prisoner’s Dilemma Game. In an experiment, university students in China and America engage in a single iteration of the game, complete belief elicitation tasks regarding their opponents’ play and take a survey including attitudinal measurements regarding their in- and out-group attitudes. Cooperation rates are higher across the two countries are higher in both cross-culture and in within-culture interactions, although not significantly. We also find that Chinese participants cooperate less than American ones. Further, female Chinese participants are more cooperative than Chinese male ones. In the cross-culture treatment, Chinese participants underestimate the likelihood of cooperative behavior of their American counterparts, while Americans overestimate the same likelihood of their Chinese counterparts. Our results also show that Chinese participants cooperate more conditionally than American ones. Finally, while we find some attitudinal in- and out-biases both they do not generate meaningful impact on cooperative behavior

EMT transcription factors snail and slug directly contribute to cisplatin resistance in ovarian cancer

<p>Abstract</p> <p>Background</p> <p>The epithelial to mesenchymal transition (EMT) is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers.</p> <p>Methods</p> <p>Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of <it>snail </it>and <it>slug </it>was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays.</p> <p>Results</p> <p>Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including <it>snail, slug, twist2 </it>and <it>zeb2</it>. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of <it>snail </it>and <it>slug</it>, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to <it>in vitro </it>drug effects.</p> <p>Conclusions</p> <p>This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for overcoming drug resistance.</p

CALIBRATION OF ENERGY SIMULATION MODEL USING IES VE SOFTWARE IN INSTITUTIONAL BUILDINGS - A CASE STUDY OF NUS SDE2

Bachelor'sBACHELOR OF SCIENCE (PROJECT AND FACILITIES MANAGEMENT

An experimental study of intra- and international cooperation: Chinese and American play in the Prisoner's Dilemma Game

We study whether intra- and international groups have different cooperation rates in the Prisoner's Dilemma Game. We report on an experiment in which university students in China and America engage in a single iteration of the game, complete belief elicitation tasks regarding their counterparts' play, and complete a survey including attitudinal measurements regarding their in- and out-group attitudes. We find that Chinese overall cooperation rates are less than American ones. Further, female participants are more cooperative than males. With respect to international cooperation, Chinese participants accurately estimate the likelihood of cooperative behavior of their American counterparts, while Americans overestimate the same likelihood of their Chinese counterparts. Our results further show that Chinese participants cooperate more conditionally than American ones. Finally, we find a more positive attitude towards one's living country is related to less international cooperative behavior, and a more positive attitude towards the other country is related to more international cooperation