Andrew: Microbes are everywhere, so a coping mechanism to survive in a world of bacteria seems evolutionary necessary. We traditionally consider our “anti-non-self ” immune system as that coping mechanism, but organisms may have also evolved a system of stable microbial coexistence. How? By inter-species gene regulation.

This is particularly interesting to me because it shows how genomics isn’t about closed, procedural, self-describing systems. Rather, genomics is contextual, recursive, and non-deterministic, like how DNA is part of the phenotype described by the genotype described by that DNA. Even better, the confusion isn’t limited to a single organism’s genome: here, squid genomic expression is modified by symbiotic bacteria to create an stable environment for the microbes and a novel phenotypic advantage for organism. So, evolutionary selection may act not only on what potential phenotypes a genome describes itself, but how that genome may be expressed as influenced by the expression of other organisms’ genomes and the environment.

…And you want to go back to “genes determine traits?” Boring!

Though bacteria are everywhere — from the air we breathe and the food we eat to our guts and skin — the vast majority are innocuous or even beneficial, and only a handful pose any threat to us. What distinguishes a welcome microbial guest from an unwanted intruder?

Research from the University of Wisconsin-Madison suggests the answer lies not with the bacteria, but with the host.

A study appearing online this week in the Proceedings of the National Academy of Sciences may help reveal what sets a platonic relationship apart from a pathogenic one. In the paper, researchers from the UW-Madison School of Medicine and Public Health and the University of Iowa identify a slew of microbe-induced genetic changes in a tiny squid, including a set of evolutionarily conserved genes that may hold the secrets to developing a mutually beneficial relationship.

“Interactions of animals with their microbiota have a profound impact on their gene expression, and to create a stable association with a microorganism requires a lot of conversation between the microbe and the host,” says UW-Madison medical microbiologist Margaret McFall-Ngai, senior author of the new study. … Continue Reading »

Researchers at the Hebrew University of Jerusalem have achieved a breakthrough in monitoring the toxin-delivery system of highly pathogenic bacteria – an accomplishment that could help pave the way for new drugs that will be capable of neutralizing those germs.

Most bacteria are harmless and do not cause infections. Some, however, are pathogenic and are equipped with special accessories that are used to deliver toxins (also termed “effectors”) into the cells of the infected person.

Numerous bacteria that cause disease, ranging from food poisoning to life threatening infection, employ a syringe-like nano-organelle (a specialized part of a cell having a specific function) that is used to inject toxic effectors into attacked host cells. This process is termed a type III secretion system (TTSS). Among these pathogens are Salmonella; the cause of typhoid fever, Yersinia; and enteropathogenic (intestinal) E. coli, which is responsible for the death of up to one million infants per year, mostly in developing countries.

The bacterial syringe employed by these bacteria is an excellent potential target for drugs (not yet available) to combat these diseases. In order to develop such drugs, however, a better understanding of the syringe functions is needed, requiring development of better methods for measuring the syringe activity.

The Hebrew University researchers – Ilan Rosenshine, the Etta Rosensohn Professor of Bacteriology at the Hebrew University Faculty of Medicine, and his associates — Erez Mills, Kobi Baruch, Xavier Charpentier and Simi Kobi — have designed a new, real-time test that allows monitoring the syringe activity. Using this test, they have discovered new properties of this system, which might be used to develop drugs that will inhibit the syringe activity and thereby prevent disease and infection by these dangerous pathogens

Their achievement was described in a recent article in the journal Cell Host & Microbe.

Source: The Hebrew University of Jerusalem

Erez Mills, Kobi Baruch, Xavier Charpentier, Simi Kobi, and Ilan Rosenshine. Real-Time Analysis of Effector Translocation by the Type III Secretion System of Enteropathogenic Escherichia coli. Cell Host and Microbe 2008 3: 104-113

Josh says:

This certainly would have a LOT of applications.