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What is the context of this research?

The immune system of squid consists of blood cells called hemocytes. These hemocytes enter the organ in which the glowing bacteria live, and destroy bad bacteria while allowing the glowing bacteria to live. We don’t understand how hemocytes know good vs bad bacteria. We know what genes and proteins are present at high levels in hemocytes, but we're not sure what each does. What I am currently working on is figuring out which proteins are involved in making the decision of which bacteria to kill. The protein, PGRP5, recognizes a molecule on the surface of some bacteria. This protein is present at very high levels in immune cells, so we think it's very important for their function.



What is the significance of this project?

All animals have microbial partners that are essential to the animal’s health. There are over 1000 bacterial species in the mammalian gut, making it difficult to study host-microbe interactions. Alterations in bacterial communities in humans have been associated with various diseases, including obesity, bowel diseases and autism. Our squid provides a uniquely simple model for understanding symbioses because the beneficial bacteria is contained to one organ and only one species of bacteria survives in this organ. This simple system allows us to manipulate experimental conditions in order to understand how host immune systems interact with symbiotic bacteria. We can apply what we learn in our squid to understanding more complex symbioses, as in the human gut.



What are the goals of the project?

The simple

Determine what immune cells use to distinguish good vs. bad bacteria.



The details

With this funding I hope to work towards determining the role of the peptidoglycan recognitions protein, PGRP5. PGRP5 is one of the most abundantly expressed genes in immune cells, which leads us to believe that it is very important for immune cell function. Specific questions I will answer will be:



1) Does PGRP5 leave the cell and kill bacteria surrounding the cell?

2) Does PGRP5 kill certain types of bacteria?

3) Where is PGRP5 located in the cell?



In the future I also plan to answer these questions with other proteins that are present at high levels in immune cells.