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August 28, 2009
Bacteria and humans
Hebrew U. professor shares science knowledge.
DEENA LEVENSTEIN
Dr. Ilan Rosenshine of Hebrew University in Jerusalem was in Vancouver last month. He talked about, among other things, the relationship between the human body (or the 1013 cells of a human body) and the bacteria around and inside it (which is about 1014 cells).
"We know now that many aspects of life can be strongly influenced by bacteria living in our intestines," said Rosenshine. There are a thousand different kinds of bacteria just in our intestines, he explained. "Imagine, each has around 4,000 genes, so it's millions of genes in addition to our 40,000 genes." The possibilities for interactions between all the different genes are numerous.
Such pearls of knowledge – that give a more in-depth understanding of life – were abundant at Rosenshine's July 27 lecture hosted by the Canadian Friends of Hebrew University (CFHU).
Rosenshine is a professor in the department of microbiology and molecular genetics at the Institute of Medical Research Israel-Canada (IMRIC) in the Faculty of Medicine at Hebrew University of Jerusalem. IMRIC focuses on creating cooperation between scientists of different disciplines, and a large percentage of the funds for IMRIC are from CFHU. The institute's goal, as stated in Rosenshine's slideshow, is, "to gain a wider perspective of the etiology [causes], prevention and treatment of human diseases."
There are five departments in IMRIC. Eighty-three research groups have seven to 10 master's level and/or doctoral students each, with a professor heading every group. There is a total of 2,500 students studying in the institution.
Rosenshine's lecture focused on the research being done in his department. He made it clear he was open to any, and many, questions – and members of the audience took him up on the offer.
"How many genes do bacteria have?" one person asked Rosenshine. The escherichia coli (e. coli) has around 4,000 genes, while other bacteria have up to 10,000 genes, Rosenshine answered. And humans? Rosenshine said that it is surprising humans have only 10 times the amount of genes as bacteria, considering how much more complex we are than them. But, it's not just the number that counts, he explained, it's the number of possible interactions. Gene A and gene B can interact with each other. If there are three genes, though, gene A can interact with B, A with C, B with C or all three with each other, and the amount of interactions jumps quickly, he said.
Rosenshine spoke about Prof. Emanuel Hanski's research on invasive strains of group A streptococcus, a bacteria that causes flesh eating disease. About this bacteria, Rosenshine said, "We all have it in our throat and most of the time it is a harmless habitant, but in some cases it causes infection and the most severe one is flesh-eating bacteria. It's a nasty disease."
Hanski is studying how one bacteria can become suddenly virulent, while others that seem identical, don't. The virulent bacteria grow very quickly inside the tissue and secrete all kinds of enzymes that chew protein and DNA, Rosenshine explained. Hanski's studies have shown that these bacteria have a system that blocks the response of the immune system as well.
At the end of the lecture, Rosenshine spoke about his own research. He works with the common bacteria that cause food poisoning: e. coli and salmonella. These bacteria "have very small syringes, nano-injectors, that attach themselves to cells and inject a battery of protein into the cells – toxins you can call them, but they aren't toxic because they don't kill the cells, just manipulate the cells to the benefit of the bacteria," he said.
Rosenshine and his team are working to figure out a way to use these bacteria as a tool, possibly "domesticating" them, so that they will be able to inject the "right" substance in the "right" place at the "right" time. They are already able to do this under laboratory conditions.
An example Rosenshine gave of a substance that could be good to inject into cells is an anti-inflammatory. Right now, the treatment for inflammation is steroids and it is very difficult treatment, Rosenshine explained, but if the treatment could be very localized, this would be a great advantage.
Other Hebrew U. faculty will be in Vancouver Sept. 12-13 for The Best of Hebrew U. – Stretch Your Mind series, which will open and close with talks by Efraim Halevy, former head of Mossad. For more information and to reserve, contact Dina Wachtel at [email protected] or 604-257-5133.
Deena Levenstein is a freelance writer from Toronto, Jerusalem and now Vancouver. You can visit her blog at deenascreations.com.
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