Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
50 years of comparative biochemistry: The legacy of Peter Hochachka
Introduction
Peter Hochachka (Fig. 1), a giant of both intellect and persona, passed away from cancer prematurely at the age of 65 in 2002. His insights and infectious enthusiasm brought metabolic biochemistry into the broader field of comparative physiology, pushing the frontiers to identify the mechanistic underpinnings of how animals work at the level of enzymes and metabolites. Much has been written about Peter's astounding contributions to diverse disciplines in comparative biochemistry and physiology, particularly his perspectives on the understanding of temperature adaptation of metabolism, facultative anaerobiosis in ectotherms, hypoxia in diving mammals, adaptation to high altitude in humans, and exercise metabolism (Storey, 2004; Somero and Suarez, 2005). In addition to a long career contributing to science through his inspiring books (Hochachka, 1980; Hochachka and Somero, 1984; Hochachka, 1994a; Hochachka and Somero, 2002), synthetic reviews (Hochachka and Mommsen, 1983; Hochachka, 1986a; Hochachka, 1988; Hochachka et al., 1996a; Hochachka, 1998) and his many seminal papers, he also had a remarkable record of training students. Many of Peter's students have gone on to careers in research, mentoring successive generations of researchers of their own. Fifteen years after his death, and coinciding with what would have been his 80th birthday, a group of former students organized a symposium that ran as a satellite to the 2017 Canadian Society of Zoologists Annual Meeting held at the University of Manitoba. The venue was appropriate because Peter was the recipient of the highest award from the society, the Fry Medal, in 1995. This award honours a researcher who has made an outstanding contribution to knowledge and understanding in zoology. Comparative Biochemistry and Physiology agreed to produce this Special Issue commemorating Peter's career and this symposium. Peter became Editor-in-Chief of CBP in 1994, and along with his co-editor Tom Mommsen, brought the journal into the era of peer review.
Peter's personal research portfolio spanned many areas of science (Fig. 2) but his contributions also inspired many researchers to push the boundaries of what can be considered comparative physiology. With his long-time friend and colleague, Charlotte Mangum, he argued the merits of a broad integrative discipline, where studies might focus on the mechanistic consequences of biochemical differences (independent of their origins) as well as origins of the differences, integrating gene and protein regulation with evolutionary history (Mangum and Hochachka, 1998). The discipline itself has changed over the decades since Peter began his research program, largely because of his efforts to integrate and synthesize from disparate fields. The collection of papers in this special issue reflects this foundation in mechanistic biochemistry, but with an emphasis on integration across levels of biological organization and awareness of the role evolution plays in the origin of diversity of physiological capacities. As a framework for reviewing Peter's contributions to the discipline, we have organized this paper into themes reflecting the organization of the satellite symposium: temperature, hypoxia, bioenergetics, evolution of metabolism, and applied biochemistry. These themes reflect Peter's research interests and are presented in an approximately chronological order although several (hypoxia, bioenergetics and evolution of metabolism) were continuous through his career.
Section snippets
Temperature
Peter's predecessors realized that temperature was one of the most important abiotic factors influencing organismal performance. One of Peter's enduring legacies is in uncovering the underlying biochemical mechanisms that link cellular and whole animal temperature sensitivities.
Temperature has pervasive influences on organisms through a combination of physiochemical effects on molecular interactions and emergent effects arising from living systems striving for homeostasis. Changes in
Hypoxia
Throughout the 1960’s, Peter was mainly interested in the thermal adaptations of the kinetic parameters of enzymes from poikilothermic organisms. By the early 1970's Peter began applying the same concepts of biochemical adaptation to better understand how animals coped with another environmental challenge: oxygen limitations. This transition was probably influenced by Ladd Prosser and Knut Schmidt-Nielsen, who were both interested in physiological adaptation to temperature and hypoxia.
Hypoxia
Bioenergetics
Bioenergetics was at the core of much of Peter's work. His earliest articles studied energy reserves and carbohydrate metabolism in fish and lobsters (Hochachka, 1961a; Hochachka et al., 1962), which led to his career-long interest in bioenergetics and biochemical adaptation. Throughout his career, Peter approached bioenergetics from a broad perspective, combining available technical approaches and integrating across levels of organization. His work on metabolic scaling, exercise metabolism and
Evolution of metabolism
Energy is the fundamental currency of life, and thus the ability to acquire energy and appropriately allocate it to processes such as growth, maintenance and reproduction is thought to be a key determinant of fitness (Brown et al., 1993). Because of this fundamental importance of energy in biology, it is no surprise that the study of energy metabolism, or the various pathways by which organisms obtain energy from nutrients and use this energy to perform their functions, has been an important
Applied biochemistry
While the core of Peter's interests was in the study of temperature and hypoxia, he was keenly aware of the importance of building bridges between disciplines, and he strived to do work that had broader ramifications (e.g. medicine, environmental science). As a result, many of his trainees took from Peter's lab very broad research interests, and used these skills to contribute in disciplines that were peripheral to Peter's main interest; a fact that Peter would have appreciated, if not
Conclusions
It is not all that uncommon for the principal investigator of a large lab to be a coauthor on dozens of papers a year. Peter's publication record, though impressive, is not unprecedented in that regard. However, he did publish an average of one solo author paper a year between 1983 and 2003. Each of these papers was an enigmatic mixture of scholarly review, novel synthesis and opinion piece. He had a knack for transforming literature reviews for grant applications into Science papers. He also
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