לוח שנה משולב

The ability of pathogens to sense and respond to changes enables them to adapt and survive in hostile environments. In particular, microbes have developed a mechanism called quorum sensing, in which they produce, detect and respond to small, secreted molecules. One of the deadliest pathogens in humans is the parasite Plasmodium falciparum (Pf), the infectious agent of the malaria disease, accounting for the death of about half a million people annually. Here, we reveal that these parasites employ a quorum sensing-like mechanism to respond to their own density and coordinate their asexual growth during the blood stage of their life cycle. Namely, Pf parasites govern their own cell density by secreting active molecule(s). Using a combination of biochemical techniques, we chemically characterized the active fraction (autoinducer-like molecule) and revealed it to be a hydrophilic, positively charged molecule of a size ranging from 100Da to 4,000Da. Further purification using high-pressure liquid chromatography (HPLC) enabled the putative detection of two metabolites. Our finding suggests that malaria parasites signal each other to coordinate their asexual growth pattern is a previously unrecognized survival strategy. Identification and further investigation of the active secreted molecule can potentially lead to the development of anti-malaria drugs.

Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concentrations of several metabolites in the brain non-invasively. I will present our work using MRS to study two aspects of brain metabolism. First, I'll talk about our work on functional MRS, whereby we look at neurochemical changes during or after learning or function. In the second half of the talk, I will focus on new methods we're developing in the lab, and in particular on our ability to measure the thermal relaxation times of metabolites, which probe specific cellular and subcellular microenvironments. I will present some preliminary data showing where and how this could be useful.