| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2003: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Mechanisms underlying regulation of SEp22 expression were further studied in pathogenic strains of Salmonella Enteritidis, isolated from poultry farms. Expression of SEp22 was dependent on the growth phases in nutritionally enriched culture medium like Luria-Bertani medium(LB), and was scarce in logarithmic phase but became rapidly increased in late-logarithmic to stationary phases. Northern blot or RT-PCR analysis of SEp22 mRNA revealed that it increased prior to the synthesis of SEp22 protein but slightly later than the increase of RNA polymerase σ factor, σ32, expression in these growth phases. However, expression of σ70 was not related with SEp22. These changes in SEp22 were cyclically repeated by transferring Salmonella into fresh LB. In contrast, induction of SEp22 was not observed even in stationary phases when cultured in nutritionally poor medium like M-9 medium, which was in part restored by addition of LB to M-9 medium. We have been examining the nutrition factor(s) in LB which supports induction of SEp22 under these conditions, and have excluded glucose or some amino acids from such factor(s). Taken together, these results suggest that expression of SEp22 is transcriptionally regulated and that environmental isolate of Salmonella, even if it potentially causes pathogenicity to host animals, does not always become pathogenic in nutritionally poor environment due to lack of expression of SEp22.
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