Day 1 :
US Army Medical Research Institute for Infectious Diseases, USA
Keynote: A proposed new selective growth medium for the isolation of enteroaggregative shiga-toxigenic strains of the emerging pathogen Escherichia coli O104:H4
Time : 09:30-10:00
Kei Amemiya received his Doctoral degree from Rutgers University in Microbiology in 1973. He did his Postgraduate studies in Gene Regulation in the laboratory of Lucy Shapiro at Albert Einstein College of Medicine, Bronx, NY. Later, he went to the National Institute of Neurological Diseases and Stroke in 1986, where he examined gene regulation in JC virus that caused the demyelinating disease progressive multifocal leuko-encephalopathy in immune suppressed patients. In 1999, he went to the US Army Medical Research Institute of Infectious Diseases, Bacteriology Division, where he has been involved in vaccine development for Burkholderiamallei and Yersinia pestis. His primary interest has been in the immune response and innate immunity in animal models.
The year 2011 was an eventful year for infectious emerging pathogens especially for the European continent. The shiga-toxin producing Escherichia coli O104:H4 was responsible for one of the largest outbreaks of gastroenteritis centered primarily in Germany leading in many cases to the life-threatening hemolytic uremic syndrome. In the same year in the United States there were at least two smaller outbreaks of food poisoning caused by E. coli O157:H7. The outbreak in Germany was found to be associated with contaminated bean sprouts while those in the US were associated with hazelnuts and romaine lettuce. Strains of E. coli O104:H4 were received from the Centers for Disease Control and Prevention. Comparative biochemical studies were performed with E. coli O157:H7 and E. coli O104:H4 using Biolog GEN III microplates and selective differential plates for identification of metabolic differences. It was also noticed the ability of the E. coli O104:H4 strains to form biofilms and their ability to bind Congo Red. The ability to activate the host innate immune response was also evaluated using human embryonic kidney (HEK) cells transfected with individual Toll-like receptors (TLR). It was during the course of these studies that it was found that E. coli O104:H4 could grow in the special medium used to measure TLR activation but neither E. coli ATCC25922 nor E. coli O157:H7 could not. With the result of these studies, a solid medium was devised that could support growth of E. coli O104:H4 but not E. coli O157:H7 or E. coli ATCC25922. The results of the studies will be presented with the proposed new selective medium that could potentially be used to differentiate enteroaggregative STEC stains of E. coli O14:H4 from E. coli O157:H7.
Uppsala University, Sweden
Time : 10:00-10:30
Leif A Kirsebom is a Professor in Biology and he received his PhD degree in Molecular Biology at Uppsala University 1985. After a Postdoctoral training 1986 through 1988 in Nobel Laureate Dr S Altmans laboratory at Yale University, USA, he started his own research group at Uppsala University. His research interests are within the fields of RNA biology, the biology of mycobacteria and development of new antibiotics. He is the Director of BMC and the Vice Chancellor advisor on international affairs at Uppsala University. Together with a colleague he started Bioimics AB, a small research company devoted to the development of new antibiotics.
Bacteria of the genus Mycobacterium are acid-fast, hardy and found to inhabit diverse environmental niches such as ground and tap water, soil, animals and humans. The Mycobacterium genus includes non-pathogenic environmental bacteria as well as opportunistic pathogens and highly successful human pathogens such as M. tuberculosis that causes TB. The diversity of ecological niches inhabited by Mycobacterium spp. demands widely varied life styles with different growth patterns and morphologies for different strains including planktonic growth, formation of biofilms and spores. They respond to variation in the environment such as ageing culture, oxygen deprivation, heat or cold shocks, pH changes, exposure to toxins/antibiotics or to the hostile immune system of the host cell by exhibiting altered growth and morphology. This ability to switch to alternate lifestyles implies global shifts in the transcriptome. Our knowledge about the diversity of the morphological variations undertaken by Mycobacterium spp. is rather limited and sporadic as is the underlying signals that induce the wide-ranging pleiomorphism among Mycobacterium species. To understand the diversity of morphological variations shown by Mycobacterium species we are studying different species and changes in their cell shape in response to different growth conditions. Microscopy data for different Mycobacterium spp. where we used different staining techniques showing variation in cell morphology will be presented. This will be followed by a discussion about new genomic, transcriptomic and proteomic data for different Mycobacterium spp. with emphasis on genes expressed under different growth conditions.
University of Pennsylvania, USA
Keynote: In vivo studies with overlapping ORF junction reveal that the major function of RRF (ribosome recycling factor) is to release ribosomes from the termination codon of post-termination complex
Time : 10:30-11:00
Akira Kaji is a Professor of Microbiology, School of Medicine, University of Pennsylvania. He contributed to the deciphering of genetic code by his discovery of the fact that the complex of poly-U with ribosome binds specifically tRNA specific for phenylalanine. He has also discovered RRF.
The termination and the initiation codons often overlap as in UAAUG. At this junction, ribosomes at UAA is released by RRF and about 25% of the upstream ribosomes re-bind to the AUG and start translating the downstream gene. In the absence of RRF the ribosome at UAA remain on the mRNA and reads it in frame with UAA. At 39ᵒ C, ribosomes at UAA due to the absence of RRF will undergo temperature dependent frame-shift resulting in the downstream reading in all frames. This frame shift is prevented by near-by SD sequence; when the termination codon is downstream of the initiation triplet as in AUGA the longer the distance between AUG and UGA the less the downstream reading from AUG; when the initiation codon is downstream of the termination codon like UAAUG, the distance between them had no effect indicating that ribosomes have more tendency to jump to the direction of 3’. Introduction of complementary sequence to the 3’-terminal region of 16S rRNA into the region surrounding the border region increased downstream reading of AUGA. Shortening of the upstream ORF to 3 codons completely abolished the downstream reading of UAAUG. However, ribosome begins translating from ATGA or AUAA. This is because the released ribosome attracted by the SD will bind to ATG codon or AUA on its way to the strong upstream SD. These results show that the major function of RRF in vivo is to release mRNA from ribosomes but this was distorted by the near-by SD sequence.