A proposed system which would permit acetate incorporation into four-carbon compounds without the presence of key enzymes of the citric acid cycle or glyoxylate cycle is described. In this system, acetyl-coenzyme A (CoA) is condensed with glyoxylate to form malate, which, in turn, is converted to oxaloacetate. Oxaloacetate then reacts with glutamate to produce ax-ketoglutarate, which is subsequently converted to isocitrate. Cleavage of isocitrate produces glyoxylate and succinate. Thus, the proposed system is similar to the glyoxylate bypass in that malate is produced from glyoxylate and acetyl-CoA, but differs from both the citric acid cycle and the glyoxylate bypass, since citrate and fumarate are not involved. Fumarase, aconitase, catalase, citritase, pyruvate kinase, enolase, phosphoenolpyruvate carboxylase, lactic dehydrogenase, a-ketoglutarate dehydrogenase, and condensing enzyme were not detectable in crude extracts of Beggiatoa. Succinate was oxidized by a soluble enzyme not associated with an electron-transport particle. Isocitrate was identified as the sole compound labeled when C1402 was added to a reduced nicotinamide adenine dinucleotide, CO2 generating system (crystalline glucose-6-phosphate dehydrogenase and glucose-6-phosphate) in the presence of a-ketoglutarate. ' Published as technical paper no. 1875, Oregon Agricultural Experiment Station. This paper was taken in part from a dissertation submitted by Sheril D. Burton in partial fulfillment of the requirements for the Ph.D. degree
Residues of isopropyl (2E,4E)-ll-methoxy-3, 7,1 l-trimethyl-2,4-dodecadienoate (Altosid®) insect growth regulator are determined in waters, soils, plants, milk, eggs, fish, shellfish, poultry and cattle tissues, blood, urine, and feces. Acetonitrile is the primary extraction solvent for all samples. Residues are extracted by high-speed blending followed by vacuum filtration. Fatty extracts are subjected to cold-temperature precipitation and filtration. Samples are cleaned up by petroleum ether partitioning and Florisil and neutral alumina chromatography. The concentrated eluants are analyzed by gas-liquid chromatography (GLC) on columns of differing polarity, using hydrogen flame ionization detectors. The identity of suspected residues is confirmed by additional GLC and by mass fragmentography. The lower limits of detection were: water samples, 0.0004–0.001 ppm; soils, blood, and urine, 0.001 ppm; forage grasses, forage legumes, and rice foliage, 0.005 ppm; and milk, eggs, fish, shellfish, poultry and cattle tissues, and feces, 0.010 ppm.
Fluvalinate is the active ingredient in Mavrik and Spur insecticides used to control insects on numerous field crops. Radiolabel experiments have shown that the residue of concern in most crops is the parent molecule. However, an analytical method was needed to determine the major hydrolytic metabolites of fluvalinate, 3-phenoxybenzoic acid (PBA) and 2-[2-chloro-4-(trifluoromethyl)anilino]-3-methylbutanoic acid (CAA), in selected crops. The method entails standard extraction and partition steps, basic hydrolysis to free conjugated metabolites, conversion to methyl esters, and determination by capillary gas chromatography / mass spectrometry. The methods were validated for the title crops with detection limits of 0.02 and 0.05 ppm, respectively, for CAA and PBA.
Melanoma is a cancer of melanocytes, the cells responsible for pigment production in the body. While melanoma has one of the highest cure rates of any cancer when detected early, once melanoma has metastasized the chances of survival dramatically decrease. Fortunately, the approval of numerous targeted and immune-based therapies for metastatic melanoma have had a significant impact on patient survival in the past 8 years. An important catalyst of this therapeutic success has been our significant understanding of the biology and genetics of melanoma. Genomic platforms, including next-generation sequencing, have rapidly increased our knowledge into the diverse sub-types of melanoma. This has allowed us to extract meaningful diagnostic information for use in the clinical management of patients, given us insight into the potential causes of melanoma, and have helped us identify new drug targets. Despite this, drug-resistance, patients not responding to treatment, and unintended side effects are all issues that need to be resolved by the field. In this talk, I will provide an overview of the somatic genetics of melanoma and discuss its diagnostic relevance in context to the current landscape of therapies for late-stage disease. This will be followed by my recent research on understanding the role and potential mechanisms of transcriptional cell states in melanoma and its significance in up-front and acquired drug resistance. Lastly, I will provide an overview of my collaborative efforts with the Broad Institute of Harvard MIT to identify melanoma specific gene dependencies as novel drug targets through use of genome-wide CRISPRknockout screens.
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