Patent ID: 8536520
Filing Date: 2013-09-17
Classification: A01H,G01N,Y10T

Abstract:
1. A method for identifying an analyte of a biological sample that is affected by a stressor comprising the steps of: (a) providing a composite biological organism sample that is comprised of two admixed substantially identical samples of biological organisms that are a control sample and an experimental sample, wherein said control sample organisms had been grown in a first nutrient medium containing predetermined amounts of first and second isotopes of a first atom within a nutrient, and said experimental sample was grown in a second nutrient medium substantially identical to said first nutrient medium but containing different predetermined amounts of said first and second isotopes of said first atom within said nutrient compared to said first nutrient medium, said first and second isotopes being other than H or D, said experimental sample being cultured with a stressing regimen containing a stressing agent for a time period sufficient for said sample to grow and said control sample being cultured for a time period sufficient for the control sample to grow with a regimen substantially identical to the stressing regimen but lacking the stressing agent and maintaining said regimen; (b) mass spectroscopically analyzing said composite biological organism sample for analyte peaks; (c) determining the ratio of first isotope to second isotope for each analyzed analyte peak; (d) determining the composite biological organism sample median isotopic ratio; and (e) comparing the ratio of first isotope to second isotope for each analyzed analyte peak with the composite biological sample median isotopic ratio, an analyte whose isotopic ratio significantly deviates from the composite biological sample median isotopic ratio being an analyte affected by the stressing agent.