When amino acids reveal blue mussel secrets

03 / 06 /2018 – C. Liénart

Processing samples for further analysis takes time and can be sometimes quite boring … but working hard is worse when it comes to results and especially good results!

After few weeks packing my mussel for SI analysis, I finally flew to Vilnius (Lithuania) at he Center for Physical Sciences and Technology where our colleagues were waiting for us with nice Lithuanian beer !

Bulk SI samples ready for analysis

Beside classic analysis of bulk carbon and nitrogen SI (δ15N and δ13C), our colleagues are working with compound specific isotopic analysis (CSIA) on amino acids and fatty acids. They also have a new and very impressive machine to measure carbon isotopic ratio by accelerator mass spectrometry, a technique used in archaeological dating, environment and biology research.

Among these very impressive machines and expensive and time consuming analysis, my little cute bivalves would be processed to reveal the δ15N signature of their amino-acids. Amino-acid are the building blocks of proteins, the latest plays a crucial role in almost all biological processes. Tracing these compounds would help understanding metabolism status, body condition and in our case, get more clues about blue mussel diet and trophic position.

Cation exchange in progress under the fumehood

Samples ready for the first step of AA extraction (hydrolysis)

Processing samples, once again takes time, as it requires 4 main steps performed over 2 days: Hydrolysis, Cation exchange, derivatization and phase extraction and then samples can be injected on the CG-C-IRMS (cute name of the machine that looks like the one on the photo but doesn’t like photo that much !)

EA-MS for bulk SI analysis

The two weeks working for 9h/day in the lab were fruitful as the signal appears to be clear enough to get interesting and exploitable data!

Let’s see now what these data will say about M.edulis diet and trophic position !


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