A comparison of the membrane IgM and IgT repertoire in rainbow trout

We sequenced the heavy chain variable regions of membrane IgM and IgT from multiple fish and predicted that given the more generalist role of the abundant IgM there would be less pressure to bias V-gene usage and DJ pairings; rather, natural selection would have favored diversity and the ability to respond to a plethora of pathogens. Conversely, as IgT is substantially less abundant in the serum than IgM and specialized in its function, there would be selective pressure to make the most out of a little, thus favoring biased V-segment usage and preferential DJ pairings.