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Analysis of E. coli Flagellin Gene Expression in Simulated Spaceflight Growth Conditions.   K.M. Hetrick1, J.O. Henderson2 and E.B. Juergensmeyer1.  1Judson College, Elgin, IL, and 2Trinity International University, Deerfield, IL.

   Prior studies have demonstrated that the population growth curves of E. coli grown in a spaceflight environment differ from those of E. coli grown on Earth.  It has been hypothesized that the formation of nutrient-rich and nutrient-poor microenvironments in the growth medium during spaceflight allows the bacteria to devote fewer resources to motility (and thus more to reproduction) than they do on Earth.  As flagellin is the major protein component of bacterial flagella, an analysis of flagellin gene (flg) expression can indicate the amount of resources the cells devote to motility at a given phase of the growth curve. 

   The purpose of this project is to determine the levels of flg expression at the transcriptional level and, by comparison to the expression levels of the housekeeping gene rrlH, determine whether flg expression changes among the various growth phases when E. coli cells are grown under three simulated spaceflight conditions.

   E. coli (ATCC 10798) cells were grown under stationary, linear vibration, slow clinorotation, and fast clinorotation conditions and collected at lag, lag/log, mid-log, and plateau phases.  Total RNA extracted from the cells of each phase of each condition was subjected to semi-quantitative RT-PCR for flg and rrlH.  The resultant amplicons were purified, and their DNA concentrations were determined.  The concentrations of the flg amplicons were then standardized to that of the corresponding rrlH amplicons.

   Preliminary data indicate that, compared to stationary growth, flg expression increases initially under vibration and fast clinorotation growth conditions and that it then decreases in the later phases.  Future projects will analyze flg expression at the translational level and seek to determine the regulation mechanisms involved in altering flg expression.

   (This project was supported by a summer research grant from Trinity International University, a Surbeck Summer Scholarship grant from Judson College, and NASA grant NAG2-1512.)