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In genetics, a strain is said to be auxotrophic if it carries a mutation that renders it unable to synthesize an essential compound. For example, a yeast mutant with an inactivated uracil synthesis pathway gene is a uracil auxotroph (e.g., if the yeast Orotidine 5'-phosphate decarboxylase gene is inactivated, the resultant strain is a uracil ...
URA3 is often used in yeast research as a "marker gene", that is, a gene to label chromosomes or plasmids. URA3 encodes Orotidine 5'-phosphate decarboxylase (ODCase) , which is an enzyme that catalyzes one reaction in the synthesis of pyrimidine ribonucleotides (a component of RNA ).
Urine drug testing is one of the most common testing methods used. The enzyme-multiplied immune test is the most frequently used urinalysis. Complaints have been made about the relatively high rates of false positives using this test. [18] Urine drug tests screen the urine for the presence of a parent drug or its metabolites.
It is not possible for the kidneys to produce urine with a specific gravity greater than 1.040 [40] but such readings can occur in urine that contains high-molecular weight substances, such as contrast dyes used in radiographic imaging. [38] Specific gravity is commonly measured with urine test strips, but refractometers may also be used. [41]
The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly the kidneys and urinary system, and specimens are easy to obtain. [1] Common urine tests include the routine urinalysis, which examines the physical, chemical, and microscopic properties of the urine; urine ...
The main metabolite excreted in the urine is 11-Nor-9-carboxy-THC, also known as THC-COOH. Most cannabis drug tests yield a positive result when the concentration of THC-COOH in urine exceeds 50 ng/mL. [10] Urine testing is an immunoassay based test on the principle of competitive binding. Drugs which may be present in the urine specimen ...
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A 1999 study of 1,179 urine specimens from victims of suspected drug-facilitated sexual assaults in 49 American states found six (0.5%) positive for Rohypnol, 97 (8%) positive for other benzodiazepines, 48 (4.1%) positive for GHB, 451 (38%) positive for alcohol and 468 (40%) negative for any of the drugs searched for. [4]