Project description:The number and type of synthetic chemicals that are being produced worldwide continues to increase significantly. While these industrial chemicals provide numerous benefits, there is no doubt that some have potential to damage the environment and health. Toxicity must be evaluated and use must be carefully controlled and monitored in order to minimize potential damage. DNA microarray technology has become an important new technique in toxicology. We are using the yeast Saccharomyces cerevisiae as a model organism for toxicological study because it is a simple, fast-growing eukaryote that has been thoroughly characterized. In order to evaluate toxicity by newly synthesized or mixture chemicals, toxicity-induced gene expression alteration profiles by known chemicals should be collected. Nitrophenols belong to the family of nitro compounds. There are three isomers, depending upon position of the functional groups at the aromatic ring: o- (CAS; 88-75-5), m- (CAS; 554-84-7) and p- (CAS; 100-02-7). It was reported that 4-nitrophenol is reported to be more toxic than 2- in animal test. In our yeast result, IC50 of o-, m- and p-nitrophenol was 3 mM, 5 mM, 1.5 mM, respectively, indicating highest toxic isomer was p-. p-Nitrophenol is reported to cause methemoglobinemia, and all isomers are suspected to be cardiovascular or blood toxicant, neurotoxicant. Keywords: stress response
Project description:Across cell types and organisms, thousands of RNAs display asymmetric subcellular distributions. The study of this process often requires quantifying abundances of specific RNAs at precise subcellular locations. To analyze subcellular transcriptomes, multiple proximity-based techniques have been developed in which RNAs near a localized bait protein are specifically labeled, facilitating their biotinylation and purification. However, these complex methods are often laborious and require expensive enrichment reagents. To streamline the analysis of localized RNA populations, we developed Oxidation-Induced Nucleotide Conversion sequencing (OINC-seq). In OINC-seq, RNAs near a genetically encoded, localized bait protein are specifically oxidized in a photo-controllable manner. These oxidation events are then directly detected and quantified using high-throughput sequencing and our software package, PIGPEN, without the need for biotin-mediated enrichment. We demonstrate that OINC-seq can induce and quantify RNA oxidation with high specificity in a dose- and light-dependent manner. We further show the spatial specificity of OINC-seq by using it to quantify subcellular transcriptomes associated with the cytoplasm, ER, and the inner and outer membranes of mitochondria. Finally, using transgenic zebrafish, we demonstrate that OINC-seq allows proximity-mediated RNA labeling in live animals. In sum, OINC-seq together with PIGPEN provide an accessible workflow for the analysis of localized RNAs across different biological systems.
Project description:Dechlorination of three tetrachlorobenzene isomers by enrichment cultures originating from a contaminated harbor follows thermodynamically favorable reactions
Project description:The ability to obtain purified biliverdin IX (BVIX) isomers other than the commercially available BVIXα is limited due to the low yields obtained by the chemical coupled oxidation of heme. Chemical oxidation requires toxic chemicals, has very poor BVIX yields (<0.05%), and is not conducive to scalable production. Alternative approaches utilizing recombinant E. coli BL21 expressing a cyanobacterial heme oxygenase have been employed for the production BVIXα, but yields are limited by the rate of endogenous heme biosynthesis. Furthermore, the emerging roles of BVIXβ and BVIXδ in biology and their lack of commercial availability has led to a need for an efficient and scalable method with the flexibility to produce all three physiologically relevant BVIX isomers. Herein, we have taken advantage of an optimized non-pathogenic E. coli Nissle (EcN(T7)) strain that encodes an endogenous heme transporter and an integrated T7 polymerase gene. Protein production of the Pseudomonas aeruginosa BVIXβ and BVIXδ selective heme oxygenase (HemO) or its BVIXα producing mutant (HemOa) in the EcN(T7) strain provides a scalable method to obtain all three isomers, that is not limited by the rate of endogenous heme biosynthesis, due to the natural ability of EcN(T7) to transport extracellular heme. Additionally, we have optimized our previous LC-MS/MS protocol for semi-preparative separation and validation of the BVIX isomers. Utilizing this new methodology for scalable production and separation we have increased the yields of the BVIXβ and -δ isomers >300-fold when compared to the chemical oxidation of heme.
Project description:Objective: To quantify changes in adipogenic gene expression in the presence of ritonavir (RTV) or tenofovir (TDF), and determine whether conjugated linoleic acid (CLA) isomers (cis9,trans11 or trans10,cis12) can mitigate detrimental effects of antiretoviral drugs. Methods: Affymetrix Mouse Genome 430 2.0 microarray was used to investigate gene expression in 3T3-L1 adipocytes treated with (1) RTV, TDF or ethanol control, or (2) ritonavir +c9,t11-CLA, ritonavir+t10,c12-CLA or ritonavir+DMSO control. RT-PCR validation of Pparg, Adipoq and Retn was carried out. ELISA and DNA binding ELISA were used to investigate secreted proteins and Pparg binding to its gene response element. Oil Red O staining was used to investigate triglyceride accumulation. Results: No effect was observed for TDF. Expression of 389 genes was altered more than 5-fold in the presence of RTV. Down-regulated genes included Pparg, Adipoq, Retn, Cfd and Cidec. Pparg and Adipoq down-regulation were confirmed by RT-PCR. PPAR-γ binding to its gene response element, adiponectin protein secretion and triglyceride accumulation were decreased by RTV. t10,c12-CLA in the presence of RTV decreased the expression of Ppargand Adipoq in microarray and RT-PCR. c9,t11-CLA increased PPAR-γ binding to its gene response element. Both isomers increased triglyceride storage in the presence of RTV. Conclusion: Ritonavir altered genes involved in adipocyte differentiation, lipid accumulation and glucose metabolism. Down-regulation of Pparg may be mediated by changes in Cepba and regulatory genes Pparg1c and Nr1h3.