Nonparametric Analysis of Temperature and Carbon Source Effects on vfr Gene Expression and Regulation
Type of DegreeMaster's Thesis
Mathematics and Statistics
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Since temperatures and carbon sources are potential conditions that affect gene expression and regulation, experiments of vfr expression and regulation in the organism Pseudomonas aeruginosa were designed and performed to address the following questions of interest: i) Do low or high temperature (30℃/42℃) have an effect on vfr expression? ii) Do low or high temperature (30℃/42℃) have an effect on vfr regulations controlled by tmRNA, GacA or GacS, which were three potential vfr regulators found in the previous laboratory work? iii) Do carbon sources like Glycerol, Glucose or Succinate have an effect on vfr expression? And iv) Do these carbon sources have an effect on tmRNA, GacA or GacS controlled vfr regulation individually? As our data (both temperatures and carbon sources) did not satisfy the normality assumption, a set of distribution-free nonparametric analyses were applied in this work. For studying the effects of the temperatures and carbon sources on vfr expressions, regulations as well as their variances, powerful and robust nonparametric analysis for location, Nemenyi test, and the Anasari-Bradley test for scale comparison were used to make final conclusions. According to the Nemenyi test, temperatures (30℃ or 42℃) affected vfr expression and but not the tmRNA, GacA or GacS controlled vfr regulations in P.aeruginosa. In addition, Ansari-Bradley test indicated that, the low temperature would not affect the variances until the late-log phase, while the high temperature affected the variances of vfr expression in P. aeruginosa from mid-log to late-log phase, but not to the end. Furthermore, high temperature affected all of the variances of tmRNA, GacA and GacS controlled vfr expression in mid-log, but only GacS regulated vfr expression in late-log, and only tmRNA dependent expression at the stationary phase in P. aeruginosa., while low temperature affected the variances of GacA regulated vfr expression at the mid-log phase, and affected the variances of tmRNA and GacS regulated expression at the late-log phase in P. aeruginosa, and at the stationary phase, none of the variances of these vfr regulations were altered by the low temperature. In order to test the effects of carbon sources on vfr expressions and regulations, similar analyses were applied to the carbon source study. According to Nemenyi approach, vfr expressions in P. aetuginosa were not be affected by any supply of Glycerol, Glucose or Succinate in NCE medias when they served as sole carbon sources. Also, since all of the tmRNA, GacA and GacS controlled vfr regulations functioned very well, vfr regulations in P. aetuginosa were also not affected in Glycerol, Glucose or Succinate supplemented NCE medias. Therefore, we conclude that carbon sources would affect neither vfr expressions nor the tmRNA, GacA and GacS controlled regulations in P. aetuginosa. According to the Ansari-Bradley test, the variances of vfr expressions in P. aetuginosa were not affected by the supply of Glycerol, Glucose or Succinate in NCE medias when they were served as sole carbon sources. The variances of tmRN, GacA, GacS controlled vfr regulations were not altered too. In conclusion, supply of Glycerol, Glucose or Succinate in NCE medias as the sole carbon sources would not affect the variances of vfr expressions in P. aetuginosa. Carbon sources also did not affect tmRNA, GacA and GacS controlled vfr regulations.