Pavement cells and country potatoes, celebrating Pierre Laurent

20 Nov 2017 - By: Jodie Rummer

Pavement cells and country potatoes, celebrating Pierre Laurent

By Jodie Rummer

Just as the pavement cells are much more than just generic cells covering the lamellar epithelium in fish gills, Pierre Laurent was also much more than a talented scientist – he was a thinker, a mentor, culinary genius, story teller, and friend. As about 70 of us discussed at the satellite symposium of the SEB in Göthenburg this past June/July – some of whom had known Pierre for many, many decades – Pierre’s structure and function approach changed the way we understand the role of the gill, the various cells types involved, and what kinds of external influences can alter gill structure and function. And, after hearing stories that sparked numerous conversations, some may also argue that Pierre’s structure-function approach to science spilled over into the kitchen; no one wants potatoes any other way than that of Pierre’s country potatoes or pommes de terre de pays.  And if you were there, you now know the secret ingredient as well.

Thanks to our organizers from Canada and the U.S., the symposium was a huge success, spanning two full days and bringing in SEB members from at least 11 different countries. Perhaps not so surprisingly, most delegates hailed from Canadian institutions, with a distant tie for second place going to our Danish and U.S. colleagues. From hagfish to Asian swamp eels, larval lampreys to larval coral reef fishes, maybe it was not a surprise that of the nearly 40 papers presented, basal to derived fishes were the basis of most. However, at least four papers did discuss non-fish taxa, and a whale was even mentioned, which really emphasizes the reach of Pierre’s approach.

Prof. Steve Perry from the University of Ottawa in Canada kicked off the symposium with a beautiful summary of Pierre’s work, largely focussing on the Pierre’s contributions to understanding the gill pavement cells in terms of acid/base regulation, plastic responses to acid-base disturbances, the presence of mitochondria, and the circumstances under which pavement cells can house proton pumps. Steve discussed Pierre’s work on ‘his beloved pseudobranch’ as well, even though the consensus is still that we don’t completely understand its origin, structure, and function. What an interesting structure that’s intrigued so many, but it has certainly become somewhat of an ongoing joke amongst our community that still, no one can definitively say more about it beyond Pierre’s findings. Steve also reviewed the more recent happenings in terms of gill structure-function relationships that stemmed from Pierre’s pioneering work, including the role of neuro-epithelial cells in CO2, O2, and NH4 sensing at the gills, work that is now being continued by his group as well as studies by Porteus, Jonz, Burleson, and others. 

Indeed, most discussions revolved around the fish gill – not only is it multifunctional, covering duties spanning gas exchange, ion and acid-base regulation, ammonia excretion, and immune function, but it can also sense environmental changes in order to make necessary adjustments. Pierre and his long-time research assistant and, later life-partner – Claudine Chevalier – were pioneers in describing the remarkable morphological and functional plasticity in the gills of fish in response to environmental challenges such as pH, hypoxia, and pollutants. These changes can occur within minutes to hours, and this concept of rapid morpho-functional adjustment is fundamental to our understanding of gill physiology today. New research on developmental and hypoxia effects on gill remodelling in cichlids was discussed by Lauren Chapmen, and many of the broad gill remodelling ideas were reviewed by Nilsson. A lot of research also focussed on the evolutionary history of the gill as well as and ontogenetic trajectories. For example, how does the role of the gill change from the most primitive to the most derived fish species? Also, what is the driving force for gill development in fish embryos? Gas exchange (e.g., oxygen uptake) or ion balance? 

Beautiful immuno-flourescence imaging done by Jonathan Wilson and colleagues over the years across broad taxa has been a key tool in addressing some of these questions by tracking mitochondrion rich cells and Na+/K+ ATPase. Colin Brauner and team have been working over the years to understand more about the oxygen/ion hypothesis with respect to ontogeny of the gill, which has very much involved Pierre’s approach in linking structure and function, both of the gill and other exchanging surfaces like the skin. Gill form and functional plasticity across development was reviewed as well, and Burggren and team’s work on environmental drivers across early development was key to this discussion.

By the end of the session, it was clear that Pierre’s work really emphasized the importance of the gill morphology-physiology interface and catalyzed what would become decades of important research. His work and collaborations have also inspired and continue to inspire scientists all over the world. But perhaps just as important, so many of the speakers shared stories of their interactions and friendships with Pierre, how much fun it was working with him, how he took the time to enjoy life, wine, and even share his secret French recipes. That theme was evident in our interactions at coffee breaks and over drinks and dinner and another reminder to of the strong, supportive, encouraging, and inspiring community we have in comparative physiology with the SEB.  And, thanks to Pierre’s personality and his contributions to science, we all had another excuse to gather for a few days to discuss how much we love our work, to brainstorm ideas, and to do so over beautiful food – perhaps country potatoes, wine, and in the best company.

 

Author: Jodie Rummer
Category: Animal Biology
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