Estimation of the average burst size of ?x174am3, cs70 for use in mutation assays with transgenic mice

Autor: Robert R. Delongchamp, Carrie R. Valentine, Heinrich V. Malling
Rok vydání: 2001
Předmět:
Zdroj: Environmental and Molecular Mutagenesis. 37:356-360
ISSN: 1098-2280
0893-6692
DOI: 10.1002/em.1043
Popis: In mutation assays using transgenic mice, with recoverable vectors such as PhiX174 am3, cs70, mutations originate from two sources: (1) in vivo mutations, that is, mutations that were fixed in the mouse, or (2) ex vivo mutations, that is, mutations that were fixed during recovery or plating. When a bacteriophage infects a bacterium, it multiplies and bursts the cell, releasing a number of phages referred to as the burst size. Our method for distinguishing between in vivo mutations and ex vivo mutations estimates the average number of bursts, the denominator of in vivo mutant frequencies, by dividing the total plaque-forming units (PFU) by the average number of phages in a burst. Herein, we outline a probability model relating observed plaque counts to the burst size and present the statistical method used to estimate the burst size. The average size of a single burst from nonrevertant phages was estimated in eight studies under the conditions of our mutation assay. The average burst size was stable across studies at 182.5 plaques per burst (standard error, 14.25). The probability that a burst is a specific size was approximated by a negative binomial distribution, which implies a Poisson-Pascal distribution for the observed plaque counts. The observed plaque counts were adequately fit by this approximation. Environ. Mol. Mutagen. 37:356-360, 2001 Published 2001 Wiley-Liss, Inc.
Databáze: OpenAIRE
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