Wan-Dong Liang

During growth,C. botulinumis always exposed to different environmental changes, such as temperature increase, nutrient deprivation, and pH change; however, its corresponding global transcriptional profile is uncharacterized. This study is the first description of the genome-wide gene expression profile ofC. botulinumin response to heat shock stress. Under heat stress (temperature shift from 37°C to 45°C over a period of 15 min), 176C. botulinumATCC 3502 genes were differentially expressed. The response included overexpression of heat shock protein genes (dnaKoperon,groESL,hsp20,andhtpG) and downregulation of aminoacyl-tRNA synthetase genes (valS,queA,tyrR, andgatAB) and ribosomal and cell division protein genes (ftsZandftsH). In parallel, several transcriptional regulators (marR,merR, andompRfamilies) were induced, suggesting their involvement in reshuffling of the gene expression profile. In addition, many ABC transporters (oligopeptide transport system), energy production and conversion related genes (glpAandhupL), cell wall and membrane biogenesis related genes (fabZ,fabF, andfabG), flagella-associated genes (flhA,flhM,flhJ,flhS, andmotAB), and hypothetical genes also showed changed expression patterns, indicating that they may play important roles in survival under high temperatures.

Streptococcus thermophilus, a gram-positive facultative anaerobe, is one of the most important lactic acid bacteria widely used in the dairy fermentation industry. In this study, we have analyzed the global transcriptional profiling of S. thermophilus upon temperature change. During a temperature shift from 42°C to 50°C, it is found that 196 (10.4%) genes show differential expression with 102 up-regulated and 94 down-regulated at 50°C. In particular, 1) Heat shock genes, such as DnaK, GroESL and clpL, are identified to be elevated at 50°C; 2) Transcriptional regulators, such as HrcA, CtsR, Fur, MarR and MerR family, are differentially expressed, indicating the complex molecular mechanisms of S. thermophilus adapting to heat shock; 3) Genes associated with signal transduction, cell wall genes, iron homeostasis, ABC transporters and restriction-modification system were induced; 4) A large number of the differentially expressed genes are hypothetical genes of unknown function, indicating that much remains to be investigated about the heat shock response of S. thermophilus. Experimental investigation of selected heat shock gene ClpL shows that it plays an important role in the physiology of S. thermophilus at high temperature and meanwhile we confirmed ClpL as a member of the CtsR regulon. Overall, this study has contributed to the underlying adaptive molecular mechanisms of S. thermophilus upon temperature change and provides a basis for future in-depth functional studies.

To investigate the association of interleukin 8 (IL-8) gene polymorphisms with the risks of inflammatory bowel disease (IBD). Single nucleotide polymorphisms (SNPs) of IL-8 gene at -845 T/C, -738 T/A, -353 A/T, -251 T/A and +678 T/C were analyzed in 183 IBD patients. They included Crohn's disease (CD, n = 41), ulcerative colitis (UC, n = 142) and healthy controls (n = 160). The methods of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polymerase chain reaction-sequence specific primers (PCR-SSP) were employed. No association was observed between any of these five SNPs in IL-8 gene with the occurrence of IBD. A specific haplotype AAT (-353 A/T, -251 T/A & +678 T/C) was over-represented in UC cases when compared with controls (31.0% vs 23.7%, P = 0.046). But the distributions of this haplotype did not show significant difference between CD cases and controls. Our data support a significant but modest association between the AAT haplotype of IL-8 gene and UC (OR = 1.441, 95%CI 1.007 - 2.063).

To investigate whether the macrophage inflammatory protein 1 alpha (MIP-1α) and apolipoprotein E (ApoE) gene polymorphisms, either alone or in combination, affect the susceptibility to inflammatory bowel disease (IBD). Genomic DNA of IBD patients with Crohn's disease (CD, n = 41) and with ulcerative colitis (UC, n = 142) and healthy controls (n = 160) was extracted and genotyped for the MIP-1α and ApoE gene polymorphisms by restriction fragment length polymorphism assay. MIP-1α -906(TA)(6)/(TA)(6) homozygotes had a significantly elevated risk of UC (OR = 1.909, 95%CI = 1.204 - 3.028). The carriers of APOE4ε4 were at a significantly higher risk for UC with OR of 2.379 (95% CI = 1.451 - 3.896). And a combination of these two loci, MIP-1α -906(TA)(6)/(TA)(6)/APOE4ε4 were strongly associated with a higher risk of UC (OR = 3.288; 95%CI = 1.777 - 6.084). The polymorphisms of MIP-1α -906 (TA)(6)/(TA)(6) and ApoE are probably independent genetic risk factors for UC. And the coexistence of both may exert an additive effect on the UC risks.