50 years of comparative biochemistry: The legacy of Peter Hochachka

01 November 2017 - By: Bill Driedzic & Jim Staples

50 years of comparative biochemistry: The legacy of Peter Hochachka

Peter Hochachka 
Peter Hochachka. Photo: University of British Columbia


By Bill Driedzic (Memorial University of Newfoundland) and Jim Staples (University of Western Ontario)

On what would have been the occasion of his 80th birthday, a Special Symposium was held to honour the legacy of Peter William Hochachka (O.C., Ph.D., D.Sc., F.R.S.C.) at the University of Manitoba on May 13 and 14, 2017.

Peter, a pioneer in the field of Comparative Animal Biochemistry, passed away in 2002 at the age of 65. Much has been written about Peter’s intellectual contributions in areas such as temperature adaptation, facultative anaerobiosis in ectotherms, diving in marine mammals, human high altitude adaptation, and exercise metabolism. It is well recognised that his work transformed the field of comparative biochemistry (see G. Somero and R.K. Suarez, Annu. Rev. Physiol. 67:25–37, 2005; K.B. Storey, Comp Biochem Physiol B Biochem Mol Biol. 39:359–69, 2004) but Peter’s legacy as a mentor is less well documented. Peter supervised 16 post-doctoral fellows, 32 PhD and 11 MSc candidates over his career. Those who trained under Peter (the F1 generation) have to this date supervised more than 750 individuals, with the count continuing to rise. A summary of Peter’s trainee information will soon be available through the Hochachka Memorial Lecture page (http://www.zoology.ubc.ca/ seminar-series/hochachka).

Peter’s PDFs include George Somero who has fathered an impressive intellectual family of his own, but it was really Peter’s supervision of PhD candidates that has made an outstanding impact. Of Peter’s 32 PhD students, 27 went on to supervise students of their own. Of these individuals, 17 held or still hold faculty positions, mostly at Canadian Universities. Of the current F2s approximately 40 hold faculty positions and again this number will increase.

The symposium was organized by a group of former Hochachka students led by Bill Driedzic and Helga Guderley, with local logistics coordinated by Kevin Campbell and Jay Treberg, F1 and F2 respectively. Symposium talks were organised around 5 major themes that ran throughout the Peter’s career: hypoxia, temperature, bioenergetics, evolution of metabolism, and ecophysiology and adaptive change.

26 talks were given at the symposium and some student examples will illustrate how Peter’s pioneering work has inspired significant advances within the field of bioenergetics. One unifying theme of Peter’s work was to understand how animals survive environmental stressors that constrain their ability to metabolise food-derived energy to synthesize ATP or generate heat. Such fundamental, discovery-based research has generated data that may help us to understand what regulates how fast animals can go, how long they can live and how some can virtually shut down metabolism under unfavourable conditions.

Low oxygen environments can limit aerobic metabolism, but some animals thrive under these conditions, including mice species that range from sea level to the near top of the Andes. Cayleigh Robertson, a PhD student from McMaster University, compared metabolic heat generation in baby mice reared at 400 metres above sea level with those reared under oxygen levels that mimicked 3500 metres elevation. The simulated high-altitude environment caused a delay in the ability of the growing mice to regulate their body temperatures, probably because there was insufficient oxygen to power heat production by brown adipose tissue.

Kate Mathers, a PhD student at the University of Western Ontario, told us of her advances in understanding how mitochondrial metabolism is dramatically and rapidly suppressed in hibernating ground squirrels. By turning down metabolism, and spending more than half of the year in hibernation, these animals can survive the winter without eating, using only their on-board energy stores. Kate’s proteomic results show that changes to key mitochondrial enzymes correspond with this metabolic suppression. Although not part of her research, Kate’s results suggest that such changes could be induced by exogenous manipulations. She took pains, however, to clarify that putting astronauts into “artificial hibernation” for interstellar travel remains solely in realm of science fiction.

The significance of polyunsaturated fatty acids to animal metabolism and lifespan was emphasized by Enrique Rodríguez (PhD student, Université du Québec à Rimouski). He told us about his studies on the membrane pacemaker theory of metabolic regulation using tropical orchid bees, species of which range in body mass by 16-fold. In this group changes in metabolic rate correlate strongly with amount of linolenate in their flight muscle. This omega-3 polyunsaturate (18:3) is an important component of membrane phospholipids in organelles such as mitochondria. While some polyunsaturates may improve animal performance they can also be damaged by reactive oxygen species, potentially contributing to aging and senescence. Enrique told us of his groups work on the significance of polyunsaturates to the oxidative stress theory of aging. Comparing several species of marine bivalves – one of which (Arctica islandica) has the longest known maximal lifespan among animals – they found that lifespan may relate to tissue polyunsaturate composition.

Student F2 and F3 trainees also presented posters in a juried competition, with prizes sponsored by the Society for Experimental Biology and the Zoology Education Trust (the charitable arm of the Canadian Society of Zoologists). From the 25 submissions two posters were judged as superior: Soren Coulson from McMaster University (Mitochondrial adaptations to high altitude in brown adipose tissue of highland deer mice) and Amanda MacCannell from the University of Western Ontario (Endogenous rhythms of thorax brown adipose tissue in the 13-lined ground squirrel). Abstracts for all talks and posters can be found here: http://home.cc.umanitoba.ca/~campbelk/ PWH%20Symposium%20schedule%20 and%20abstracts.pdf.

By all accounts the meeting was a great success, with over 100 delegates (including Brenda, Peter’s wife) and excellent presentations. A generation of students should now appreciate their scientific lineage. Peter was most certainly celebrated and his important contribution of mentoring his students so that they would become mentors was recognised.

Mathers, K.E., McFarlane, S.V., Zhao, L. and Staples, J.F. (2017). Regulation of mitochondrial metabolism during hibernation by reversible suppression of electron transport system enzymes. Journal of Comparative Physiology B, 187:227–234. DOI 10.1007/s00360-016-1022-0

Rodriguez, E., Weber, J-M, Pagé, B., Roubik, D.W., Suarez, R.K. and Darveau, C.-A. (2015) Setting the pace of life: Membrane composition of flight muscle varies with metabolic rate of hovering orchid bees. Proceedings of the Royal Society B, 282: 20142232, http://dx.doi.org/10.1098/rspb.2014.2232

 



Category: Animal Biology
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